Emerson MVME147 User Manual

Introduction

The MVME147 MPU VMEmodule contains a port to the Small Computer Systems Interface (SCSI) bus. The hardware interface is the WD33C93 SCSI interface controller.

To relieve you of having to follow SCSI bus protocol, the SCSI firmware allows you to pass commands to the bus through high level command packets. Standard command packets are furnished, as well as custom SCSI sequence packets that you may easily modify to f it particular applications. With this method, the firmware interface can greatly speed up your software development cycle.

The SCSI firmware resides in two 128K x 8 EPROMs and is co-resident with MVME147Bug, the debug monitor for the MVME147 MPU VMEmodule.

Features

The SCSI firmware offers the following features: ❏ Custom SCSI sequence packets that allow creation of customized

functions

❏ TARGET role ❏ Multitasking -- up to 64 concurrent peripheral devices ❏ High level support of SCSI devices ❏ Interrupt mode allows real-time applications ❏ Polled mode -- non-interrupt operation ❏ DMA with memory/scatter/gather ❏ Multiple-user interface allows concurrent operation through independent

drivers

❏ Six entry points ❏ Thirty-one "canned" or standard function packets

GENERAL INFORMATION

Modes of Operation

When using the SCSI firmware, you have a choice of two modes of operation:

Interrupt mode and polled mode.

GENERAL INFORMATION

Interrupt mode is the most processor-efficient mode of operation. Multitasking is allowed for TARGETs that support arbitration, reselection,

and the message-out phase. When using the interrupt mode, you must specify the interrupt level in the

packet description (refer to the packet descriptions in Chapter 7). The processor is returned to the caller; i.e., the driver in most applications,

whenever the SCSI bus is slowed down (between phases), or whenever the TARGET disconnects with a pending reselection; this allows commands on the bus to be overlapped.

Polled mode is a slow, processor-inefficient mode of operation. Provided for the user who cannot tolerate interrupts. This mode is selected by specifying level 0 in the user packets. Only a single thread is provided on the SCSI bus. When you branch to the command entry, the processor stays in the SCSI

firmware until the command is finished or until interaction is required (refer to the MVME147 SCSI Firmware E ntry Points section that follows to perform a command in this mode).

Exceptions; e.g., bus parity errors are checked by polling the registers in the WD33C93. This checking method is slow.

Therefore, this non-interrupt polled mode is recommended only for applications that cannot tolerate interrupts.

MVME147 SCSI Firmware Entry Points

The SCSI firmware provides six entry points via the branch table located in the non-volatile RAM and contains jump instructions to the SCSI firmware in the debugger EPROMs. You are advised to use the non-volatile RAM entry addresses instead of the ROM addresses because in future debugger releases the SCSI firmware may move within the EPROMs. The branch table offsets are:

1. $FFFE077C (command entry)

2. $FFFE0782 (reactivation entry)

3. $FFFE0788 (interrupt entry)

4. $FFFE078E (FUNNEL command entry)

5. $FFFE0794 (come-again entry)

1-2

Note

MVME147 SCSI Firmware Entry Points

6. $FFFE079A (RTE entry)

Within the SCSI firmware, which can stand alone without the debug monitor, the first six longwords are the branch table entries referenced above. The hex offsets provided reside within the non-volatile RAM.

The following are descriptions of the six entry points. For more detailed descriptions of their use, refer to the Interface Rules for Multiple Callers section in Chapter 5.

$FFFE077C: COMMAND ENTRY

Branches to FUNNEL entry.

$FFFE0782: REACTIVATION ENTRY

Branches to FUNNEL entry. All preprocessed commands are activated in the interrupt service routine through software interrupt.

$FFFE0788: INTERRUPT ENTRY

This entry point is used as the interrupt service routine address for vectors on the MVME147 module. Vector $45 (offset $114 from VB R) is the WD33 C93 in terrupt vector used by the SCSI firmware. Vector $46 (offset $118 from VBR) is the DMA channel interrupt vector and vector $4B (offset $12C from VBR) is the software interrupt vector used by the SCSI firmware to service queued commands.

The SCSI firmware initializes these vectors.

The following intermediate return resumes with an interrupt which gives control to the interrupt entry:

$02: WAIT FOR INTERRUPT (OPEN)

Intermediate status indicating that an WD33C93 interrupt brings the processor control back to the SCSI firmware. The MVME147 can accept more commands if it is currently disconnected from the SCSI bus (refer to the SCSI Firmware

1-3

GENERAL INFORMATION

Interrupt Structure paragraph in Chapter 4) or SCSI bus activity is slowed down. Additional commands may be sent to the SCSI firmware for a different peripheral device.

$FFFE078E: FUNNEL COMMAND ENTRY

This entry point is used by applications that require multiple interfaces to the SCSI firmware. Unlike the single user command entry, you may issue commands anytime the firmware does not require an RTE to be performed. If an RTE is required, and you wish to send a command at the same time, you may accomplish both by using the RT E entry (described below). The use of the FUNNEL command entry causes the FUNNEL module to examine the state of the SCSI bus, determine if the bus is currently in use, and send the command to the bus if it is not in use. If the bus is currently in use, the FUNNEL module checks if the device is not busy so it can preprocess or queue the command and return to the caller with an intermediate status of $A002. This preprocessed or queued command is processed and sent to the SCSI bus when the bus is free.

$FFFE0794: COME-AGAIN ENTRY

Branches to FUNNEL entry. All the queued commands are serviced in the interrupt service routine through software interrupt.

$FFFE079A: RTE ENTRY

The SCSI firmware notifies the user/caller that an RTE instruction needs to be executed by the RTE bit (13) of the returned status word. If this bit is 0, an RTE is required; if this bit is 1, an RTE is not required (the SCSI firmware does not execute the RTE instruction so as not to preempt a task in a VERSAdos or SYSTEM V/68 environment). SCSI firmware users may inherit an RTE from another caller because of the multiple caller interface. When an RTE is inherited from another caller, the use of the RTE entry may be required to send down a new command before executing an RTE instruction.

Equipment Supported

The following list shows the cont roller type assignments for SCSI controllers explicitly supported by the SCSI firmware, and the drives supported by each. /f3Note, however, that Motorola does not n ecessarily endorse or r ecommend

1-4

Equipment Supported

any particular controller, nor does Motorola ass ume responsibility for the operation of equipment manufactured by non-Motorola companies. Refer to Appendix A for information on how to use this firmware program.

CONTROLLE

CODE TYPE

0D Floppy TEAC FD235J 2

0E Winchester Televideo

0F Winchester Common

10 Winchester Seagate WREN

11 Winchester M icropolis 1375 900475-11-2B 1,2

12 Streaming Archive Viper

DEVICE P ART

MANUFACTUR

ER/MODEL

1002921-1B 1,2,3

7000/7400/3500 Floppy Tape

Command Set Floppy

77774620 1,2

III 94161

Winchester Seagate WREN

IIIHH 94211

Winchester Seagate SWIFT

94351-126

Winchester Seagate SWIFT

94351-201

2060s Tape

Streaming Archive Viper

2150s Tape

Streaming Tanberg 3620

(8533) 60Mb Tape

Streaming Tanberg 3640

(8534) 120M b Tape

75912134 1,2

22100-007 1,2

22300-004 1,2

NUMBER NOTES

1,2,3

1,2

1-5

GENERAL INFORMATION

CONTROLLE

CODE TYPE

CONTROLLE

CODE TYPE

13 Winchester Seagate WREN

14 Winchester Seagate ST

16 1/2" Tape Kennedy

17 Winchester Synchronous

DEVICE P ART

Streaming Tanberg 3660

Tape

Cassette TEAC MT-

Tape

DEVICE P ART

Winc hester Seagate WREN V

Winches ter Ma xt or 43 80S 2 Winches ter Ma xt or 87 60S 2

Winchester Seagate ST

Winchester Miniscribe 1,2

1/2" Tape HP 88780A 2

MANUFACTUR

ER/MODEL

(8535) 150M b

2ST/45S2

MANUFACTUR

ER/MODEL

IV 94171

94181

157N/M

125N/M

1096N

296N/M

9612/9662

Common Command Set

NUMBER NOTES

77777000 1,2

77777750 2

1,2,5

U92-9662-0004 2

1-6

Equipment Supported

CONTROLLE

CODE TYPE

18 8mm Tape Exabyte EXB-

DEVICE P ART

Floppy 2,3

Devices Supported Under Common Command Set

Winchester Televideo

Floppy Televideo

Winchester Seagate WREN

Winchester Micropolis 1375 900475-11-2B 1,2 Winchester Seagate WREN

Winc hester Seagate WREN V

Winchester Seagate SWIFT

Winches ter Ma xt or 43 80S 2 Winches ter Ma xt or 87 60S 2,4

Devices Supported Under Synchronous Common Command Set

Winc hester Seagate WREN V

Winches ter Ma xt or 43 80S 2,4 Winches ter Ma xt or 87 60S 2,4

MANUFACTUR

ER/MODEL

8200

7000/7400/3500

III 94161

IIIHH 94211

IV 94171

94181

94351-126

94351-201

94181

NUMBER NOTES

820010-009 2

1,2

1002921-1B 1,2,3

77774620 1,2

1,2

77777000 1,2,4

77777750 2,4

75912134 1,2

1,2

77777750 2,4

NO TE:

1. Supported in firmware revision 1.0 and later.

2. Supported in firmware revision 2.0 and later.

1-7

GENERAL INFORMATION

3. Common Command Set for floppy matches SCSI II rather than revision 17B.

4. Under Common Command Set the cache is not enabled on these devices.

5. Seagate /M means Motorola proprietary.

6. Firmware assembly order number is: 966096. Order number for tape drives is (85xx) as shown with drive type. Order from: Tanberg Data A/S, Data Storage Division, P.O. Box 9, Korsvoll N-0808, Osl o 8, Norwa y, Phone +47 2 18 90 90 or Tanberg Data Tech. Center, 1077 Business Center Circle, Newbury Park, CA 91320, Pho n e +1 (80 5) 37 5- 2 50 0 .

Manual Terminology

MOTOROLA

SCSI Guide Book; Adaptive Data Systems, Inc., 2627 Pomona Boulevard, Pomona, CA 91768

SCSI Small Computer Systems Interface; draft X3T9.2/82-2, Revision 14; Computer and business Equipment Manufacturers Association, 311 First Street, N.W., Suite 500, Washington, D.C. 20001

WD33C92 and WD33C93 SCSI Bus Interface Controller Data Manual; Western Digital, 2445 McCabe Way, Irvine, CA 92714.

Common Command Set (CCS) of the Small Computer System Interface ( SCSI) X3T9.2/85-52 - Revision 4B; Computer and Business Equipment Manufacturer’ s Association, 311 First Street, N.W., Suite 500, Washington D.C. 20001

Manual Terminology

Throughout this manual, a convention has been maintained whereby data and address parameters are preceded by a character which specifies the numeric format as follows:

1-9

GENERAL INFORMATION

$ dollar specifies a hexadecimal

number % percent specifies a binary number & ampersand specifies a decimal number

Unless otherwise specified, all address references are in hexadecimal throughout this manual.

An asterisk (*) following the signal name for signals which are level significant denotes that the signal is true or valid when the signal is low.

An asterisk (*) following the signal name for signals which are edge significant denotes that the actions initiated by that signal occur on high to low transition.

In this manual, assertion and negation are used to specify forcing a signal to a particular state. In particular, assertion and assert refer to a signal that is active or true; negation and negate indicate a signal that is inactive or false. These terms are used independently of the voltage level (high or low) that they represent.

1-10

Introduction

The SCSI firmware requests "canned" functions from SCSI disk controllers and from SCSI tape controllers. Some of these functions are disk read and write,

disk format, tape read and write, and tape positioning operations. The "canned" functions are only provided for the supported SCSI devices that are listed in the Equipment Support ed section in Chapter 1.

If you want to perform a function that is not "canned", or you want to communicate with SCSI devices that are not supported by the SCSI firmware, you do not have to rewrite the SCSI firmware. Any SCSI operation may be performed through the use of the custom SCSI packet.

A custom SCSI packet may be used for a variety of needs. Following are some typical needs:

1. You need to perform a command on a suppor ted SCSI disk controller that

is not "canned" in the SCSI firmware. (For example, an offline COPY command is not supported directly by the SCSI firmware. You may perform this COPY command through the custom SCSI packet.)

2. You wish to interface the MVME147 module to a SCSI optical disk

controller.

3. You wish to request linked commands from a disk controller.

CUSTOM SCSI PACKETS

There are three classes of custom SCSI packets, described in the following sections. They are:

Initiator role custom packet TARGET enable custom packet TARGET sequence custom packet

Initiator Role Custom Packet

The initiator role custom packet is shown in the following table.

Even Byte \ Odd Byte \

CUSTOM SCSI PACKETS

FC B8 74 30 +$00 Controller LUN Device LUN +$02 Status Byte 0 Status Byte 1 (No te 1) +$04 Script Pointer (MSW) +$06 Script Pointer (LSW) +$08 Command Table Pointer (MSW) (Note 2) +$0A Command Table Pointer (LSW) (Note 2) +$0C 0000 +$0E Flag = 0 0 0 0 +$10 Scatter/Gather Count +$12 0000 +$14 0 0 Function Code (1C) +$16 Interrupt Level Vector Number +$18 Status Byte 2 Status Byte 3 (No te 1) +$1A 0 0 Retry Count

$00 00000xxx Controller logical unit

number

$01 00000xxx Device logical unit

number

$02 xxxxxxxx Status from SCSI

firmware (byte 0) (Note 1)

$03 xxxxxxxx Status from SCSI

firmware (byte 1)

(Note 1) $04 xxxxxxxx xxxxxxxx Script pointer (MSW) $06 xxxxxxxx xxxxxxxx Script pointer (LSW) $08 xxxxxxxx xxxxxxxx Command table

pointer (MSW) (Note

$0A xxxxxxxx xxxxxxxx Command table

pointer (LSW) (Note

$0C 00000000 00000000 Reserved

2-2

Initiator Role Custom Packet

$0E 00000000 Initiator role

(TARGET enable/sequence bit

undefined) $0F 00000000 Reserved $10 xxxxxxxx xxxxxxxx Scatter/gather entry

count. No retry

on firmware if

scatter/gather DMA

is used

because command

scatter/gath er ta ble

could

be modified after the

command is complete

if disconnect/reselect

occurred. $12 00000000 00000000 Reserved $14 00000000 Reserved $15 00011100 SCSI function ($1C =

custom SCSI ) $16 00000xxx Interrupt level (7 to

0)(0 = polled mode)

$17 xxxxxxxx Vector number to use

upon return $18 xxxxxxxx Status from SCSI

firmware (byte 2)

(Note 1) $19 xxxxxxxx Status from SCSI

firmware (byte 3)

(Note 1) $1A 00000000 Reserved $1B 0000xxxx Retry count --

number of SCSI

command

retries (refer to

scatter/gathe r r etry

count

above)

2-3

CUSTOM SCSI PACKETS

NOTES:

1. Refer to Chapter 3.

2. Command Table = 384 bytes RAM work area.

This first class is used for command execution and/or message passing through the MVME147 SCSI firmware while the module is playing the initiator role. According to SCSI definition, an initiator is a SCSI device (usually a host system) which requests an operation to be performed by another SCSI device; a TARGET is a SCSI device which performs an operation requested by an initiator. Initiator role custom packets request operations to be performed by other SCSI devices. For the initiator role, certain data structures are needed by the SCSI firmware. These are:

1. SCRIPT: A "script" is a sequence of SCSI bus phases that the initiator expects the TARGET to perform when executing a requested command. For example, a disk read (under SCSI rules) would typically require the following SCSI bus phases:

MESSAGE-OUT: The IDENTIFY message is sent from the initiator to the TARGET. This message contains the identification of the desired logical unit of the selected disk controller that the initiator wishes to read. The message also indicates whether the initiator is capable of reselection.

COMMAND: The Command Descriptor Block (CDB) is sent during the command phase to specify the block number to read, the logical unit to read from, the number of blocks to read, and whether the command is linked.

DATA-IN: The actual data is transferred from the TARGET to the initiator during the data-in phase.

STATUS: The disk controller sends the status of the command that was executed during this phase.

MESSAGE-IN: During this phase, the disk controller sends a message describing the execution of the command it just executed. The linked command information would appear in the message sent during this phase, for example.

BUS DISCONNECT: After a disk controller sends a command complete message, it disconnects from the SCSI bus by releasing the BSY* signal.

The justification for a script is as follows. On the SCSI bus, the TARGET is always the SCSI device that dictates the sequence of bus phases that occurs during a communication with th e initiator (this communication is

2-4

Initiator Role Custom Packet

commonly called a "thread"). The script allows the SCSI firmware to follow the TARGET bus sequences and also allows the firmware to resume a disconnected thread once a disconnect/ rese lect occurs. Because the SBC allows "multithreading" of SCSI commands on the SCSI bus, a script is necessary to resume any disconnected threads. Without a script, the SCSI firmware would not have any way to check whether the TARGET performed the command that was requested through the CDB.

The following table gives the possible SCSI bus phases.

PHASE

Bus Free No activity on the bus. SEL* and BSY* are not

Arbitration SCSI devices arbitrate for the use of the bus by

(Re)Selection One SCSI device selects another device by

Information Transfer Phases: Command initiator

to TARGET

Status TARGET

Data in

Data out

Message in

DIRECTION NOTES

activated.

activating BSY* and their ID.

activating SEL* along with its ID and th e ID for the other device.

A command tells the TARGET what is requested by the initiator. The CDB is passed during this phase.

The status of a particular command is passed to

to initiator TARGET

to initiator

initiator to TARGET

TARGET to initiator

initiator. Examples: good, busy, check. Data is transferred from the TARGET to the

initiator as a result of a data phase requested in the CDB.

Data is transferred from the initiator to the T A RGE T a s a result of a data pha se r equested in the CDB.

Messages are sent to the initiator to send bus, command, and controller information. Examples: command complete, save data pointer, restore data pointer, message reject.

2-5

CUSTOM SCSI PACKETS

PHASE

Message out

DIRECTION NOTES

initiator to TARGET

Messages are sent to the TARGET to send bus, command, and controller information. Examples: identify, initiator detected error, abort, device reset.

Scripts only specify the information transfer phases. The bus free, arbitration, and selection phases do not need to be specified in a script. The script codes that are understood by the MVME147 SCSI firmware are listed in the following table. (Note that TARGET role scripts are described in the Target Sequence Custom Packet section in this chapter.

CODE

$00 END OF SCRIPT Init iator

DISCONNECT TARGET $04 COMMA N D PHASE Initi ator and TARGET $08 DATA-OUT PHASE Initiator and TARGET

$0C DATA-IN PHASE Initiator and TARGET

$10 STATUS PHASE Initiator and TARGET $14 MESSAGE-OUT PHASE Initiator and TARGET $18 MESSAGE-IN PHASE Initiator and TARGET

$1C END OF SCRIPT TARGET

NOT DEFINED Initiator $20 TARGET WAIT, TARGET

NO DISCONNECT $24 TARGET WAIT, TARGET

DISCONNECT $28 TARGET WAIT, TARGET

NO DISCONNECT

DATA RECEIVED

$2C TARGET WAIT, TARGET

DISCONNECT

DATA RECEIVED

BUS PHASES ROLE

2-6

Initiator Role Custom Packet

If you suspect data integrity error, you can set up the SCSI script to execute the data phase and then disconnect from the bus (script code 0x2c) or just return as an intermediate return without disconnect from the bus (script code 0x28). Firmware executes the data phase and then returns the firmware parity error status, if any, command packet, and command table back to you.

You can examine the data as well as the firmware status to decide what SCSI status should be returned to initiator. After the status is determined, a new TARGET sequence command packet needs to be sent to firmware with status, message (for message-in phase), and proper scripts to complete the SCSI bus command.

For the previous disk read example, the script would be: $14,$04,$0C,$10,$18,$00.

The above sequence of codes may be written anywhere in the MVME147accessible space. It may even be ROMed. The script pointer in the custom SCSI packet is the address of the first entry of the script. In the example, it would point to the $14. Therefore, the message-out phase should always be the first phase in any initiator script.

2. COMMAND TABLE (384 bytes of RAM). The second data structure required by the SCSI firmware for the execution of a custom SCSI packet is a Command Table.

For unsupported controllers, the control of certain functions (parity checking, DMA, linked commands, SCSI rules, DMA scatter/gather, SYNC/ASYNC transfer) is dictated to the firmware through the status/flag byte of the Command Table.

The CDB is one of the pieces of the command table. The user of the initiator role custom SCSI packet loads the CDB to be passed to the SCSI target that is to be selected. The initiator role custom SCSI packet has a Command Table pointer which is the address of the first word of this data structure. Unlike the script, the Command Table must be in MVME147-accessible RAM because the firmware writes to portions of the table. All the user accessible pieces of the Command Table are shown in the following table.

Even Byte \ Odd Byte \

2-7

CUSTOM SCSI PACKETS

FC B8 74 30 +$00 Status/Flag Byte Retry Count (00) +$02 Link Pointer (MSW) +$04 Link Pointer (LSW) +$06 Command Length +$08 SCSI Command Descriptor Block (CDB) +$0A SCSI Command Descriptor Block (CDB) +$0C SCSI Command Descriptor Block (CDB) +$0E SCSI Command Descriptor Block (CDB) +$10 SCSI Command Descriptor Block (CDB) +$12 SCSI Command Descriptor Block (CDB) +$14 SCSI Status Initiator SCSI Address (0 t o 7) +$16 Data Length (MSW) +$18 Data Length (LSW) +$1A Data Pointer (MSW) (Note 1) +$1C Data Pointer (LSW) (Note 1) +$1E Me ssa ge-In Length +$20 Message-In Pointer (MSW) +$22 Message-In Pointer (LSW) +$24 Message-Out Length +$26 Message-Out Pointer (MSW) +$28 Message-Out Pointer (LSW) +$2A Reserved +$2C Reserved

. . .

+$60 Sector Number in Error (MSW) +$62 Sector Number in Error (LSW) +$64 SCSI Con troller Status 0 0 +$66 T ransfer Address

2-8

Initiator Role Custom Packet

Even Byte \ Odd Byte \

FC B8 74 30 +$68 T ransfer Address +$6A 0000 +$6C 0000 +$6E 0000 +$70 0000 +$72 Command Offset +$74 Sense Data Block

. . .

+$9E Sense Data Block

$00 xxxxxxxx Status/flag byte

0....... Lnk -- link flag bit

disabled

1....... Lnk -- link command

tables, support linked commands

.0...... Parity disabled

.1...... Parity enabled --

MVME147 checks SCSI

bus parity

..0..... DMA on

..1..... DMA off flag --

disable DMA for data out/in

...0.... CSCSI -- custom

sequence flag: checks

2-9

CUSTOM SCSI PACKETS

status (Note 2)

...1.... CSCSI -- does not

check SCSI status (Note 2)

....0... SCSI firmware uses

SCSI rules (Note 3)

....1... SASI mode flag --

firmware uses SASI rules (Note 3)

.....1.. SG -- scatter/gather

enable, use data points to

scatter/gather table. During

custom SCSI packet, you have to set this

bit if scatter/ gather DMA operation is

required

.....0.. SG -- scatter/gather

disable

2-10

......1. SYNC -- synchronous

transfers enable On INITIATOR role,

SCSI firmware initiates synchronous

data transfer request. On TARGET role,

SCSI firmware initiates synchronous

data transfer request IF initiator

DOES NOT do so before first data

phase.

Initiator Role Custom Packet

......0. ASYNC --

asynchronous transfers enable

$01 00000000 Retry count (must be

00)

$02 xxxxxxxx xxxxxxxx Link pointer (MSW) --

for linked commands. Valid only if link flag

bit = 1

$04 xxxxxxxx xxxxxxxx Link pointer (LSW) $06 xxxxxxxx xxxxxxxx Command length --

length of the CDB (in bytes)

$08 xxxxxxxx xxxxxxxx SCSI command

descriptor block (CDB)

SCSI draft revision 17B allows 12 bytes

maximum length (Note 4)

$0A xxxxxxxx xxxxxxxx SCSI (CDB) $0C xxxxxxxx xxxxxxxx SCSI (CDB) $0E xxxxxxxx xxxxxxxx SCSI (CDB) $10 xxxxxxxx xxxxxxxx SCSI (CDB) $12 xxxxxxxx xxxxxxxx SCSI (CDB) $14 xxxxxxxx SCSI status

On INITIATOR role, this is the copy of status on

$64. On T ARGET role, you

can set SCSI status here.

Bit 0(LSB), 5 and 6 is vendor unique. Bit 7

is reserved. The status set here is ORed with

2-11

CUSTOM SCSI PACKETS

the firmware status ($64) and sent to initiator.

If you determine to use bit 1-4, such as data

parity error, the firmware non-zero status on

bit 1-4 has higher priority. You should load

this byte with the appropriate status and set

up the SCSI script for status phase before the

target sequence packet is sent.

$15 xxxxxxxx Initiator SCSI addr ess

in TARGET mode (0 to 7)

(only used in TARGET mode)

$16 xxxxxxxx xxxxxxxx Data length (MSW) --

number of bytes expected during data-

in or data-out phase

$18 xxxxxxxx xxxxxxxx Data length (LSW)

$1A xxxxxxxx xxxxxxxx Data pointer (MSW) -

- to memory area where firmwar e reads

(data out) or writes (data-in) (contiguous

buffer)

$1C xxxxxxxx xxxxxxxx Data pointer (LSW)

2-12

Initiator Role Custom Packet

$1E xxxxxxxx xxxxxxxx Message-in length --

bytes expected during message-in

(max=258 for extended

messages)

$20 xxxxxxxx xxxxxxxx Message-in pointer

(MSW) -- to RAM buffer where

firmware stores received

messages

$22 xxxxxxxx xxxxxxxx Message-in pointer

(LSW)

$24 xxxxxxxx xxxxxxxx Message-out length --

bytes expected to be transferred in

message-out phase, has to be non-zero if

message-out phase is required (max=258

for extended messages)

$26 xxxxxxxx xxxxxxxx Message-out pointer

(MSW) -- to RAM buffer where

firmware takes messages to

transfer to TARGET

$28 xxxxxxxx xxxxxxxx Message-out pointer

(LSW)

$2A xxxxxxxx xxxxxxxx Reserved $2C xxxxxxxx Reserved

.. .. ..

$60 xxxxxxxx xxxxxxxx Sector number in

error (MSW)

2-13

CUSTOM SCSI PACKETS

$62 xxxxxxxx xxxxxxxx Sector number in

error (LSW)

$64 xxxxxxxx Initiator role - Status

byte from SCSI controller

(unchanged) TARGET r ole -

firmware determined SCSI

status $65 xxxxxxxx Reserved $66 xxxxxxxx xxxxxxxx Trans fer address -- for

a read or writ e.

This is the address of

the next byte to be

transferred. $68 xxxxxxxx xxxxxxxx Trans fer address -- for

a read or writ e.

This is the memory

address of the next

byte to be transfe rred.

. .

$72 xxxxxxxx Command error

status byte (valid

following

a command error

$0B) -- SCSI

command in

error. $73 xxxxxxxx Offset within packet. $74 xxxxxxxx xxxxxxxx Sense data block

(controller-

dependent).

This is the

information returned

by the

2-14

Initiator Role Custom Packet

controller follow ing a check status and

a request sense data command. Valid

informatio n if bit 14 (additional status)

is set. This block is

firmware private area and only

used on the INITIATOR role.

. .

$9E xxxxxxxx xxxxxxxx Sense data block

. .

NOTE S:

1. Points to scatter/gather table if scatter/gather bit = 1 in byte 0.

2. If = 0 and if status is "check", SCSI firmware interprets returned SCSI status, and sends a request sense command to t he con troller; if status is = busy, infinite retries are performed. If = 1, SCSI firmware does not read the SCSI status from the command table, and returned status word in the packet reflects only firmware status.

3. Must be 0. MVME147 SCSI firmware ONLY supports SCSI devices.

4. In TARGET mode, the CDBs is received from the SCSI bus and it will be returned to the user without any modif ication with CDB length. When a target LUN is not enabled or when ’target device reset’ or ’abort’ message is received, the CDB received by the target role firmware will not be returned to the user. Instead, a error code will be returned.

Example: Sending linked commands to a disk controller You intend to implement a read-modify-write function for your particular

operating system. The benefit of linking commands on the SCSI bus is a better utilization of bus bandwidth. When two commands are linked, the TARGET does not disconnect between commands. After the message-in phase completes one command, the TARGET switches to command phase for the second command. The arbitration and selection phases are eliminated for the

2-15

CUSTOM SCSI PACKETS

second command. The following linked command example may be performed on the Archive 2150 disk controller (it supports linked commands). The SCSI firmware does not support linked command with flag.

PACKET FOR THE LINKED COMMAND EXAMPLE:

PACKET DC.W $0400 CONTROLLER LEVEL=4, DEVICE LUN=0 DS.W 1 RETURNED STATUS WORD (BYTES 0 AND 1)+2 DC.L LSCRIPT SCRIPT POINTER +4 DC.L CT1 COMMAND TABLE POINTER +8 DC.W 0 RESERVED +C DC.W 0 INITIATOR ROLE CUSTOM SEQUENCE +E DC.W 0 RESERVED +10 DC.W 0 RESERVED +12 DC.W $001C FUNCTION CODE=CUSTOM SCSI SEQUENCE +14 DC.W $0260 INTERRUPT LEVEL 2, VECTOR $60 +16 DS.W 1 STATUS BYTES 2 AND 3 +18 DC.W 3 RETRY COUNT=3 +1A

SCRIPT for a READ followed by a WRITE:

2-16

LSCRIPT DC.B $14 MESSAGE OUT (IDENTIFY) DC.B $04 COMMAND (READ) DC.B $0C DATA IN DC.B $10 STATUS DC.B $18 MESSAGE IN DC.B $04 COMMAND (WRITE) DC.B $08 DATA OUT DC.B $10 STATUS DC.B $18 MESSAGE IN DC.B $00 END OF SCRIPT

(LINKED COMMANDS REQUIRE AS MANY COMMAND TABLES AS THERE ARE PIECES OF THE LINKED COMMAND. I.E. FOR A READ/WRITE LINKED COMMAND, 2 TABLES ARE REQUIRED)

Initiator Role Custom Packet

*****************************COMMAND TABLE FOR THE FIRST COMMAND************** CT1 DC.B %11000000 * X LINK FLAG ON * X PARITY CHECKING ENABLED * X DMA ENABLED * X CUSTOM SEQ. FLAG=> FIRMWARE CHECKS STATUS * X FIRMWARE USES SCSI RULES (RESELECT, ETC.) * X RESERVED X NO SCATTER/GATHER OPERATION X ASYNC SCSI TRANSFER DC.B 0 RETRY COUNT=0 DC.L CT2 THE ADDRESS OF THE SECOND COMMAND TABLE DC.W 6 COMMAND LENGTH = 6 (GROUP 0 COMMAND) DC.B $08 READ COMMAND DC.B $00 LUN=0, BLOCK ADDR MSB=0 DC.B $00 BLOCK ADDR DC.B $86 (FULL BLOCK ADDR=$00086) DC.B $04 4 BLOCKS REQUESTED DC.B $03 CONTROL BYTE: FLAG BIT=1, LINK BIT=1. * see *NOTE below the second command table. DC.B 00 DON’T CARE DC.B 00 DON’T CARE DC.B 00 DON’T CARE DC.B 00 DON’T CARE DC.B 00 DON’T CARE DC.B 00 DON’T CARE DS.B 01 USER’S STATUS BYTE IS STORED HERE DC.B 07 SCSI INITIATOR ADDRESS = $07 DC.L $400 4 BLOCKS * $100 BYTES/BLOCK= $400 BYTES DC.L BUFF DATA BUFFER ADDRESS DC.W 1 MESSAGE IN AREA ALLOCATION= 1 BYTE DC.L MSIN1 MESSAGE IN AREA POINTER DC.W 1 MESSAGE OUT AREA ALLOCATION = 1 BYTE DC.L MSOUT1 MESSAGE OUT AREA POINTER DS.B 342 REMAINING OF THE 384 BYTE COMMAND TABLE MSIN1 DS.B 1 MESSAGE IN AREA FOR COMMAND TABLE #1 MSOUT1 DC.B $C0 THE IDENTIFY MESSAGE FOR LUN 0, WITH RESELECTION BUFF DS.B $400 4 BLOCK DATA BUFFER

2-17

CUSTOM SCSI PACKETS

*****************************COMMAND TABLE FOR THE WRITE COMMAND************** CT2 DC.B %01000000 * X LINK FLAG OFF * X PARITY CHECKING ENABLED * X DMA ENABLED * X CUSTOM SEQ. FLAG=> FIRMWARE CHECKS STATUS * X FIRMWARE USES SCSI RULES (RESELECT, ETC.) * X RESERVED. X NO SCATTER/GATHER X ASYNC SCSI TRANSFER DC.B 0 RETRY COUNT=0 DC.L 0 NO LINK ADDRESS PROVIDED. DC.W 6 COMMAND LENGTH = 6 (GROUP 0 COMMAND) DC.B $0A WRITE COMMAND DC.B $00 LUN=0, BLOCK ADDR MSB=0 DC.B $00 BLOCK ADDR DC.B $86 (FULL BLOCK ADDR=$00086) DC.B $04 4 BLOCKS REQUESTED DC.B $00 CONTROL BYTE: FLAG BIT=0, LINK BIT=0. DC.B 00 DON’T CARE DC.B 00 DON’T CARE DC.B 00 DON’T CARE DC.B 00 DON’T CARE DC.B 00 DON’T CARE DC.B 00 DON’T CARE DS.B 01 USER’S STATUS BYTE IS STORED HERE DC.B 07 SCSI INITIATOR ADDRESS = $07 DC.L $400 4 BLOCKS * $100 BYTES/BLOCK= $400 BYTES DC.L BUFF DATA BUFFER ADDRESS DC.W 1 MESSAGE IN AREA ALLOCATION= 1 BYTE DC.L MSIN2 MESSAGE IN AREA POINTER DC.W 1 MESSAGE OUT AREA ALLOCATION = 1 BYTE DC.L MSOUT2 MESSAGE OUT AREA POINTER DS.B 342 REMAINING OF THE 384 BYTE COMMAND TABLE MSIN2 DS.B 1 MESSAGE IN AREA FOR COMMAND TABLE #1 MSOUT2 DC.B $00 NO MESSAGE OUT PHASE FOR THE SECOND COMMAND.

2-18

TARGET Enable Custom Packet

Note

A linked command with the flag bit set is not supported, and the flag bit is ignored if it is set.

TARGET Enable Custom Packet

The TARGET enable custom packet is shown in the following table.

Even Byte \ Odd Byte \

FC B8 74 30

+$00 Controller LUN Device LUN +$02 Status Byte 0 Status Byte 1 (No te 1) +$04 Not Used +$06 Not Used +$08 Command Table Pointer (MSW) (Note 2) +$0A Command Table Pointer (LSW) (Note 2) +$0C 0000 +$0E Flag = C 0 0 0 +$10 0000 +$12 0000 +$14 0 0 Function Code (1C) +$16 Interrupt Level Vector Number +$18 Status Byte 2 Status Byte 3 (No te 1) +$1A 0 0 Retry Count

$00 00000xxx Controller logical unit

number

$01 00000xxx Device logical unit

number

$02 xxxxxxxx Status from SCSI

firmware (byte 0) (Note 1)

2-19

CUSTOM SCSI PACKETS

$03 xxxxxxxx Status from SCSI

firmware (byte 1)

(Note 1) $04 xxxxxxxx xxxxxxxx Not used $06 xxxxxxxx xxxxxxxx Not used $08 xxxxxxxx xxxxxxxx Command table

pointer (MSW) (Note

$0A xxxxxxxx xxxxxxxx Command table

pointer (LSW) (Note

2) $0C 00000000 00000000 Reserved

$0E 1....... TARGET role

.1...... TARGET enable

..000000 Reserved

$0F 00000000 Reserved $10 00000000 0000 0000 Reserved $12 00000000 0000 0000 Reserved $14 00000000 Reserved $15 xxxxxxxx SCSI function ($1C =

Custom SCSI

sequence) $16 00000xxx Interrupt level (7 to 1) $17 xxxxxxxx Vector number to use

upon return $18 xxxxxxxx Status from SCSI

firmware (byte 2)

(Note 1) $19 xxxxxxxx Status from SCSI

firmware (byte 3)

(Note 1) $1A 00000000 Reserved $1B 00000000 Retry count must be 0

NOTES:

2-20

1. Refer to Chapter 3.

2. Command table = 384 bytes RAM work area.

TARGET Enable Custom Packet

This second "class" of custom packets is used to enable TARGET role service by the MVME147 SCSI firmware. All eight SCSI-defined logical units can be independently serviced through the firmware. Each logical unit needs to be enabled separately. In other words, a TARGET enable packet is sent for each logical unit that you want to service. The TARGET enable packet should not be deallocated even after TARGET is enabled and command is received (final return for TARGET enable). It is recommended that you use the same packet for TARGET enable and TARGET sequence. The last packet should be saved until the next TARGET command is received.

Packet description: WORD $00: CONTROLLER LUN -- This is the target SCSI address of the

MVME147. Because target firmware already knows the SCSI address this field is used to compare with the known target SCSI address. If the address does not match, an ID error is reported when the packet is received. DEVICE LUN -- This number (0 through 7) specifies which TARGET logical unit is to be enabled. All eight may be enabled, but only one is enabled per TARGET enable call.

WORD $02: STATUS bytes 0 and 1 -- These status bytes are the codes

returned to you by the firmware. (For code definitions, refer to Chapter 3.)

WORDS $04 and $06:

SCRIPT POINTER -- The script pointer is not used by the firmware for the TARGET enable call.

WORDS $08 and $0A:

COMMAND TABLE POINTER -- This is the pointer to the command table (384 bytes of RAM). Each TARGET logical unit needs one command table. No sharing of command tables is allowed among the enabled logical units. When a TARGET command is complete, this command table must not be deallocated because of future use. However, the command table area could be used by subsequent TARGET commands.

WORD $0E=$C000:

This code classifies the custom packet as a TARGET enable call to the firmware.

WORD $14: The code of $1C classifies the packet as a custom packet.

2-21

CUSTOM SCSI PACKETS

WORD $16: The interrupt level must be no-zero because TARGET role

support is not used in non-interrupt mode. (If TARGET role support were done in polled mode, nothing else would be able to run on the MVME147 other than the TARGET firmware because the microprocessor would poll for a selection as a TARGET.) The vector number is used to provide the return path to you. (You take over that vector and point it to your service routine.) IMPLEMENTATION NOTE: It is highly recommended that you assign a unique return vector for each enabled TARGET logical unit in order to keep the service of each LUN separate

and independent from the other LUNs. WORD $18: Not used by the firmware for the TARGET enable call. WORD $1A: Not used by the firmware for the TARGET enable call.

TARGET Sequence Custom Packet

The TARGET sequence custom packet is shown in the following table.

Even Byte \ Odd Byte \

FC B8 74 30 +$00 Controller LUN Device LUN +$02 Status Byte 0 Status Byte 1 (No te 1) +$04 Script Pointer (MSW) +$06 Script Pointer (LSW) +$08 Command Table Pointer (MSW) (Note 2) +$0A Command Table Pointer (LSW) (Note 2) +$0C 0000 +$0E Flag = 8 0 0 0 +$10 0000 +$12 0000 +$14 0 0 Function Code (1C) +$16 Interrupt Level Vector Number +$18 Status Byte 2 Status Byte 3 (No te 1)

2-22

TARGET Sequence Custom Packet

+$1A 0 0 Retry Count

$00 00000xxx Controller logical unit

number

$01 00000xxx Device logical unit

number

$02 xxxxxxxx Status from SCSI

firmware (byte 0) (Note 1)

$03 xxxxxxxx Status from SCSI

firmware (byte 1)

(Note 1) $04 xxxxxxxx xxxxxxxx Script pointer (MSW) $06 xxxxxxxx xxxxxxxx Script pointer (LSW) $08 xxxxxxxx xxxxxxxx Command table

pointer (MSW) (Note

$0A xxxxxxxx xxxxxxxx Command table

pointer (LSW) (Note

2) $0C 00000000 00000000 Reserved

$0E 1....... TARGET role

.0...... TARGET sequence

..000000 Reserved

$0F 00000000 Reserved $10 00000000 00000000 Reserved $12 00000000 00000000 Reserved $14 00000000 Reserved $15 xxxxxxxx SCSI function ($1C =

custom SCSI

sequence) $16 00000xxx Interrupt level (7 to 1) $17 xxxxxxxx Vector number to use

upon return $18 xxxxxxxx Status from SCSI

firmware (byte 2)

(Note 1)

2-23

CUSTOM SCSI PACKETS

$19 xxxxxxxx Status from SCSI

firmware (byte 3)

(Note 1) $1A 00000000 Reserved $1B 0000xxxx Retry count must be 0

NOTES:

1. Refer to Chapter 3.

2. Command Table = 384 bytes RAM work area.

This third "class" of custom packets is used to service received commands and messages for an enabled MVME147 TARGET logical unit. When an initiator selects the MVME147 as a TARGET, the firmware switches to TARGET role, determines which logical unit is desired by the initiator, and returns to the TARGET service routine (through the vector supplied in the TARGET enable packet) for user service of the initiator request. If the initiator that selected the MVME147 as a TARGET does not send an illegal message, the TARGET role firmware sequences the SCSI bus to the command phase, read in a CDB, store the CDB in the command table provided through the TARGET enable packet, and return through the vector provided for the selected logical unit for command service. If the command was received, a final status of $xx17 or an intermediate status of $xx06 is stored in the status word of the particular LUN packet. The final status code of $xx17 is returned if an IDENTIFY WITH RESELECTION message was received. The intermediate status code of $xx06 is returned if ATN* was not asserted during selection or if an IDENTIFY WITHOUT RESELECTION message was received. You then use a TARGET sequence packet to service the command.

IMPLEMENTATION NOTE: The SCSI firmware DOES provide information to you as to which SCSI initiator is requesting service from the TARGET in command table byte offset $15.

2-24

Packet description: WORD $00: CONTROLLER LUN -- This binary number must match the

SCSI level of the MVME147 as in Target Enable Custom Packet. DEVICE LUN -- This number identifies the particular logical unit to service an initiator request.

WORD $02: STATUS bytes 0 and 1 -- This is the firmware status word that

tells you how your packet was serviced (finished, error, etc.).

Note

TARGET Sequence Custom Packet

WORDS $04 and $06:

SCRIPT POINTER -- The address of the TARGET script to be performed to service the initiator request. In TARGET role, the MVME147 controls the SCSI bus. The TARGET script tells the firmware which information transfer phases to cycle through to service the initiator request that was encoded in the CDB.

In TARGET role, the names of the information transfer phases are consistent with initiator role. By SCSI definition, transfer direction is always referenced to the initiator. That is, the message in pha se is a message tr ansfer INTO the initiator. For T ARGET ro le the message-in phase is still INTO the initiato r (notice it is OUT of th e TARGET).

TARGET scripts to service commands do not include command phases. Below are examples of TARGE T scripts for two CDBs; one is a receive CDB and the other is a send CDB. Example 1: Receive (peripheral device type = processor devices) CDB byte 0: $08 Command is a receive CDB byte 1: $20 The desired LUN is 1 CDB byte 2: $00 Allocation length MSB CDB byte 3: $04 Allocation length CDB byte 4: $00 Allocation length LSB CDB byte 5: $00 Control byte=0: no link, no flag

Target script for example 1:

DC.B $0C DATA-IN PHASE DC.B $10 STATUS PHASE DC.B $18 MESSAGE-IN PHASE DC.B $1C END OF TARGET SCRIPT

The command table contains the information required to carry out the bus phase. For example, the data pointer tells the firmware where the buffers are located in MVME147accessible memory.

1. During the data-in phase, the $400 bytes are sent to the initiator.

2. During the status phase, the GOOD status is sent to the initiator.

2-25

CUSTOM SCSI PACKETS

3. During the message-in phase, the COMMAND COMPLETE message is sent to the initiator.

4. The END OF TARGET SCRIPT code causes the firmware to disconnect from the bus and return to you (through the vector provided in the TARGET sequence packet) with a final status of $xx18, indicating the TARGET script was completed successfully.

Example 2: Send (peripheral device type = processor d evices): CDB byte 0: $0A Command is a write CDB byte 1: $20 The desired LUN is 1 CDB byte 2: $00 Allocation length MSB CDB byte 3: $03 Allocation length CDB byte 4: $00 Allocation length LSB CDB byte 5: $00 Control byte=0: no link, no flag

Target script for example 2:

DC.B $08 DATA OUT PHASE DC.B $10 STATUS PHASE DC.B $18 MESSAGE IN PHASE DC.B $1C END OF TARGET SCRIPT

2-26

1. During the data-out phase, the initiator writes data to the MVME147 . The byte count is $300.

2. During the status phase, the GOOD status is sent.

3. During the message-in phase, the COMMAND COMPLETE message is sent.

4. The end of TARGET script code causes the firmware to disconnect from the SCSI bus and return to you through the vector provided in the TARGET sequence packet.

WORDS $08 and $0A:

COMMAND TABLE POINTER -- The address of the TARGET role command table. Below is a description of the requirements of the TARGET command table. TARGET COMMAND TABLE DESCRIPTION: CT word 00: (Byte 0 -- status/flag byte.) Bit assignments:

TARGET Sequence Custom Packet

D7 = Not used by the TARGET role firmware. (This is the link bit.

Command linking is not accomplished with the use of this bit.)

D6 = Not used by the TARGET role firmware. (This is the parity

bit. )

D5 = Not used by the TARGET role firmware. (This is the DMA

disables bit. DMA is used in TARGET role: 0 = DMA, 1 = no DMA)

D4 = MUST be zer o. No t used b y the TARGET role firmware. (This

is the interpret bit and only relevant for initiator role.)

D3 = Not used by the TARGET role firmware. (This is the

SASI/SCSI rule bit. The TARGET role module determines which rule to follow by the initiator assertion of ATN and the re-select option bit of the IDENTIFY message.)

D2 = This is a scatter/gather bit. If DMA is enabled, the data

pointer in the command table could be used to point to the scatter/gather table if this bit is 1.

D1 = 1 = SYNC transfer enable.

0 =ASYNC transfer enable.

D0 = Reserved.

(Byte 01): Not used by the TARGET role firmware. Must be set to $00. CT words $02 and $04: LINK POINTER. Not used by the TARGET role

firmware. CT word $06: COMMAND LENGTH. Not used by the TARGET sequence ca ll.

(The CDB received from initiator is stored in the command table that was provided in the TARGET enable call. You may use the same command tables for the enable and sequence calls to interpret receive CDB, but the TARGET sequence call does not make use of the command length and of the CDB itself.)

CT words $08 through $12: COMMAND DESCRIPTOR BLO CK. Not used by the TARGET sequence call. (Refer to CT word 06 above for command length.)

CT word $14, even byte: User SCSI STATUS. For a TARGET sequence, you can set the vendor unique bits in the status byte. The MVME147 SCSI firmware sends the contents of this byte ORed with the firmware SCSI status byte in offset $64 if a status phase code is encountered in the TARGET script. (Odd byte $15: initiator SCSI address which is interfacing with the TARGET role firmware.)

2-27

CUSTOM SCSI PACKETS

CT words $16 and $18: DATA LENGTH. The number of bytes to transfer during either the data-in or the data-out phase. Not used if DMA is enabled and SG bit is set in status/fla g byte in word o.

CT words $1A and $1C: DATA POINTER. If a DATA-IN code is in the TARGET script, the firmware starts transferring data FROM the contiguous data buffer pointed to by this pointer. If a DATA-OUT code is in the TARGET script, the firmware starts transferring data TO the contiguous data buffer pointed to by this pointer. This pointer points to SG table if DMA S G is used.

CT word $1E: MESSAGE-IN LENGTH. Not used by the TARGET role firmware for the message byte count in the message-in phase.

CT words $20 and $22: M ESSAGE-IN POINTER. If a message-in code is in the TARGET script, the firmware sends the messages from message-in buffer where this pointer points.

CT word $24: MESSAGE-OUT LENGTH. Not used by the TARGET role firmware.

CT words $26 and $28: MESSAGE-OUT POINTER. If the initiator that is threaded to the MVME147 sends an extended message to the MVME147, the firmware stores it in the message buffer that is pointed to by this pointer. (The ATN condition is only serviced if the ATN signal is asserted during selection or certain phases. The initial IDENTIFY message is handled internally by the firmware for threading purposes. If the ATN condition arises during a phase that can be serviced, the message that is received from the initiator is stored in the buffer pointed to by this message-out pointer.)

2-28

CT word $64, even byte : TARGET role firmware SCSI status byte set by firmware during target sequence packet execution..

The remaining bytes of the command table are reserved. Packet word $0E=$8000: This word classifies the custom SCSI packet as a TARGET sequence. Packet word $14=$001C: This word classifies the packet as a custom SCSI sequence. Packet word $16: The interrupt level must be non-zero because TARGET role is only supported

for interrupt mode. The vector number provides the return path for the firmware to you.

Packet word $18:

TARGET Sequence Custom Packet

STATUS BYTES 2 and 3. Not used by the TARGET role firmware. Packet word $1A: RETRY COUNT. Not used by the TARGET role firmware.

2-29

CUSTOM SCSI PACKETS

2-30

PACKET RETURN STATUS

Packet Return Status

When packets are returned to the user, they contain two status words: one with an offset of $02 and the other with an offset of $18, as shown in the tables below, respectively. The first table details the status codes contained in the word at offset $02. Refer to the Interface Rules for the SCSI Firmware section in Chapter 5 for additional information. Also, refer to the command table returned fields.

Status word offset $02 1508 0700

Control Flags

Bits 12-8 (reserved)

Bit 13 (RTE FLAG) (of interest only to the

programmer)

1 = This return was not preceded by an

interrupt and is the first return since command entry. In this case, no RTE is required.

0 = This return was preceded by an interrupt

and is not the first return, therefore, an RTE is required to continue processing from where an interrupt occurred. Register A3 has a pointer to a register save area (D0-D7, A0-A6).

Bit 14 (ADDITIONAL ST ATUS)

1 = External status is valid. 0 = External status is not valid.

Status Code (Refer to Table 3-1)

PACKET RETURN STATUS

Bit 15 (FINALSTAT)

1 = Intermediate return. 0 = Final status.

The script processing completed successfully, OR the script processing encountered a fatal error.

Note

*(L1 *(L2 *(L3 *(L4 Status word offset $18

This does not mean that the operation that the user requested on the SCSI was successful. The status is contained in the status code (bits 7-0.)

3-2

1512 1108 0704 0300

SCSI

Phase Reserved Flags

Status (0 if not used)

| Bit 0

(RES) Reserved)

Bit 1

(ILI) Incorrect length indicator.

Request Sense

Bit 2 (EOM)

End of media.

Bit 3 (FM)

Filemark

Bit 4 (COMMAND

RETRY)

1 = Retries were

performed.

Bit 5 (COMMAND RE-

TRY OVERFLOW)

1 = Retry overflow.

The command was retried "retry count" times.

Packet Return Status

Bits 6 and 7 (reserved)

*(L1 *(L2 *(L3 *(L4 *(L5 *(L6 *(L7 Return Status Packet

Even Byte \ Odd Byte \

3-3

PACKET RETURN STATUS

FC B8 74 30

+$00

+$60 Block Number in Error (MSW) +$62 Block Number in Error (LSW) +$64 SCSI Con troller Status 0 0 +$66 T ransfer Address +$68 T ransfer Address +$6A 0000 +$6C 0000 +$6E 0000 +$70 0000 +$72 Command Offset +$74 Sense Data Block

+$9E Sense Data Block

. .

$60 xxxxxxxx xxxxxxxx Block number in err or

(MSW) -- This is the returned information

bytes taken from bytes

3-6 following an err or from a SCSI device

and a request sense command.

$62 xxxxxxxx xxxxxxxx Block number in err or

(LSW)

$64 xxxxxxxx Status byte from SCSI

controller

(unchanged) $65 xxxxxxxx Reserved $66 xxxxxxxx xxxxxxxx Trans fer address -- for

a read or writ e.

3-4

Packet Return Status

This is the memory address of the next byte

to be transferred.

$68 xxxxxxxx xxxxxxxx Trans fer address -- for

a read or writ e.

. .

$72 xxxxxxxx Command error

$73 xxxxxxxx Offset within packet. $74 xxxxxxxx xxxxxxxx Sense data block

. .

$9E xxxxxxxx xxxxxxxx Sense data block

. .

status byte (valid following

a command error $0B)

. .

Table 3-1. Packet Status Codes

CODE

MEANING NOTES

Intermediate Return

Codes

$02 Wait for interrupt; command

door open. OK to send new commands for other devices to firmware.

$04 A message has been received.

You must interpret.

$06 (TARGET mode) received a

command from initiator, no disconnect allowed.

$08 (TARGET mode) data

received from initiator, user must interpret then continue with new t_seq.

1,9

3-5

PACKET RETURN STATUS

Table 3-1. Packet Status Codes

CODE

MEANING NOTES

Intermediate Return

Codes

$09 (TARGET mode) data

received from initiator with parity error, user must interpret then continue with new t_seq.

Final Return Codes

$00 GOOD. Script processing is

OK. $01 Undefined problem. 2 $02 TARGET has Received Data

without error, and user may

interpret then continue with

new t_seq. $03 Interrupt handler was

entered with no pending IRQ

($F00050). $04 Reselection not expected

from this TARGET. $05 TARGET thinks it is working

on linked commands but the

command table does not. $06 Linked command has error

status code; command has

been aborted. $07 Received an illegal message. 2 $08 The message we have tried to

send was rejected. $09 TARGET Encountered a

parity error in data

transfer(in) phase and user

must interpret then continue

with new t_seq.

1,9

3-6

Table 3-2. Packet Status Codes (cont’d)

Packet Return Status

CODE

$0A SCSI bus reset received (A1 pointing to packet list). (Refer to the

SCSI Bus Reset Packet section in Chapter 7.)

$0B Command error (bad command code, bad timing, or command

door was closed when a command was received) = 00. Custom SCSI sequence: controller level not equal to "147 local level", or interrupt no t on. Fo rmat: for mat with d efects on a con - tro ller t ype not supported. Controller reset: controller not SCSI type. Space (tape): undefined mode. Mode select (tape): undefined controller

type. Mode sense (tape): undefined controller type. $0C Size error (invalid format code). 2 $0D Bad ID in packet or local ID. 2

$0E Error in attach (not previously attached, bad device LUN,

unsupported controller).

$0F Busy error (device has a command pending). 2 $10 There is disagreement between initiator and TARGET regarding

the number of bytes that are to be transferred.

$11 Received a BERR* while in DMA mode. 2 $12 Selection time-out. TARGET does not respond. 2 $13 SCSI protocol violation. Controller reset: controller not SCSI. 2 $14 Script mismatch. CHECK STATUS. If SCSI status within

command table (offset $14 for initiator role) is zero, then assume script mismatch, otherwise use SCSI packet status.

$15 Script mismatch. The TARGET sequence of operation did not

match the script. $16 I llegal SCSI state machine transition. 2 $17 Command has been received (TARGET r ole). Disconnect allowed. 2 $18 Script complete in TARGET role. 2 $19 Script complete and new command loaded (TARGET role linked

command).

$1A TARGET module called. TARGET role not supported. 2

MEANING NOTES

3-7

PACKET RETURN STATUS

Table 3-3. Packet Status Codes (cont’d)

CODE

$1B TARGET module rejected an initiator message and returned with

this status to a particular LUN service routine.

$1C TARGET module sent a check status wi th an "illegal reques t" sense

block to some initiator because the particular LUN that the initiator wanted was not enabled.

$1D TARGET module sent a busy status to the calling initiator because

the particular LUN that the initiator wanted was already busy

servicing a command. $1E TARGET received ABORT message from the SCSI initiator. 2 $1F TARGET received DEVICE RESET message from the SCSI

initiator.

MEANING NOTES

Request-Sense-Data Error-Class 7 Codes

(Controller-Dependent)

$20 NO SENSE. Indicates that there is no specific sense key

information to be reported for the designated logical unit. $21 RECOVERED ERROR. Indicates that the last command

completed successfully with some recovery action performed by

the TARGET. Details can be determined by examining the

additional sense bytes and information bytes. $22 NOT READY. Indicates that the logical unit addressed cannot be

accessed. Operator intervention may be required to correct this

condition. $23 MEDIUM ERROR. Indicates that the TARGET detected a

nonrecoverable error co ndition that was probably caused by a flaw

in the medium or an error in recording data. $24 HARDWARE ERROR. Indicates that the TARGET detected a

nonrecoverable hardware failure (for example, controller failure,

device failure, parity er ror, etc.) while performing the command or

during self test. $25 ILLEGAL REQUEST. Indicat es that ther e was an illegal para meter

in the command descriptor block or in the additional parameters

supplied as data.

2,3

3-8

Table 3-4. Packet Status Codes (cont’d)

Packet Return Status

CODE

$26 UNI T ATTENTION. Indicates that the removable media may

have been changed or the TARGET has been reset.

$27 D ATA PROTECT. I ndicates that a command that reads or writes

the medium was attempted on a block that is protected from this operation.

$28 BLANK CHECK. Indicates that a write-once read-multiple dev ice

or a sequential access device encountered a blank bl ock while reading or a write-once read-multiple device encountered a nonblank block while wri tin g.

$29 VENDOR UNIQUE. Used for reporting vendor unique conditions

(for Saber AP = format complete).

$2A COPY ABORTED. Indicates that a copy or a copy and verify

command was aborted due to an error condition.

$2B ABORTED COMMAND. Indicates that the TARGET aborted the

command. The init iator may be able to reco ver by trying the command again.

$2C EQUAL. Indicates a search data command has satisfied an equal

comparison.

$2D VOLUME OVERFLOW. Indicates that a buffered peripheral

device has reached an end-of-medium and data remains in the buffer that has not been written to the medium. A recover buffered data command may be issued to read the unwritten data from the buffer.

$2E MISCOMPARE. Indicates that the source data did not match the

data read from the medium.

$2F RESERVED. This sense key is reserved. 2,3

MEANING NOTES

SCSI Status Returned in Status Phase

$31 SCSI status = $02. CHECK. 2,4 $32 SCSI st atus = $04. CONDITION MET. 2,4 $34 SCSI status = $08. BUSY. 2,4

$38 SCSI status = $10. INTERMEDIATE/GOOD. 2,4 $3A SCSI status = $14. INTERMEDIATE/CONDITION MET/GOOD. 2,4 $3C SCSI status = $18. RESERVATION CONFLICT. 2,4

2,3

3-9

PACKET RETURN STATUS

Table 3-5. Packet Status Codes (cont’d)

CODE

MEANING NOTES

Request-Sense-Data Error-Class 0 through 6 Codes

(Controller-Dependent)

$40 NO ERROR STATUS. 2,5,6 $41 NO INDEX SIGNAL. 2,5,6 $42 NO SEEK COMPLETE. 2,5,6 $43 WRITE FAULT . 2,5,6 $44 DRIVE NOT READY. 2,5,6 $45 DRIVE NOT SELECTED. 2,5,6 $46 N O TRACK 00. 2,5,6 $47 MULTIPLE DRIVES SELECTED. 2,5,6 $49 CARTRIDGE CHANGED. 2,5,6

$4D SEEK IN PROGRESS. 2,5,6

$50 ID ERROR. ECC error in the data field. 2,5,7 $51 DATA ERROR. Uncorrectable data error during a read. 2,5,7 $52 ID ADDRESS MARK NOT FOUND. 2,5,7 $53 DATA ADDRESS MARK NOT FOUND. 2,5,7 $54 SECTOR NUMBER NOT FOUND. 2,5,7 $55 SEEK ERROR. 2,5,7 $57 WRITE PROTECTED. 2,5,7 $58 CORRECTABLE DATA FIELD ERROR. 2,5,7

$59 B AD BLOCK FOUND. 2,5,7 $5A FORMAT ERROR. (Check track command. 2,5,7 $5C UNABLE TO READ ALTERNATE TRACK ADDRESS. 2,5,7

$5E ATTEMP TED TO DIRECTLY ACCESS AN ALTERNATE TRACK. 2,5,7

$5F SEQUENCER TIME OUT DURING TRANSFER. 2,5,7

$60 INVALID COMMAND. 2,5,8

$61 ILLEGAL DISK ADDRESS. 2,5,8

$62 ILLEGAL FUNCTION. 2,5,8

$63 VOLUME OVERFLOW. 2,5,8

3-10

Packet Return Status

NO TES :

1. Intermediate return codes. Bit 15-1, actual word=$80xx, $90xx, etc.

2. Final return codes.

3. Sens e key s tatus co des for Req uest-Sen se-Data er ror -- cl ass 7. A n of fset of $20 i s added to all sense key codes.

4. The SCSI status sent from the controller is ANDed with $1E, shifted right one bit, and $30 added.

5. Sense key status codes for Request-Sense-Data error -- classes 0-6. An offset of $40 is added to all sense key codes.

6. Drive error codes.

7. Controller error codes.

8. Command errors.

9. Intermediate return codes, the no disconnection is allowed according to the script.

3-11

PACKET RETURN STATUS

3-12

SCSI FIRMWA RE

INTERRUPT STRUCTURE

SCSI Firmware Interrupt Structure

The SCSI interface firmware was designed for processor efficiency. Whenever the SCSI bus is in a state that does not need monitoring, the firmware releases the processor so it may perform other functions such as user tasks and lower priority events. In these cases, an interrupt brings processor control back to the firmware.

A return vector is provided to the SCSI firmware in all cases through the packet pointed to by register A2. Whenever the firmware returns to the user through this return vector, it flags whether the processor was brought back to the firmware through an external interrupt. This flagging is done by the RTE FLAG bit in the status word stored in the user packet. If the bit = 1, no RTE is to be performed by the user. If the bit = 0, eventually an RTE is required by the user to return the processor to the interrupted task.

Similarly, whenever the RTE instruction is to be executed, the user must restore the registers before executing the RTE. This restoration of registers is mandatory to properly restore the task that was interrupted. Upon a return through the user vector, address register A3 contains an address of a save area where the registers were saved. If A3 = 0, then no registers were saved (that is, no interrupt was taken and the RTE FLAG bit should be a 1 ).

Processor control is returned to the user in a variety of ways: Intermediate status:

$02 Wait for interrupt (open) $04 Message received $06 Command received (TARGET role)

or Final status.

Refer to the Interface Rules for a Sing le Caller section in Chapter 5 for details. For the intermediate statuses, control is given back to the firmware in two

ways. One is through an WD33C93 interrupt (WAIT FOR INTERRUPT (OPEN)). The other return mechanism is through a direct branch or jump into

SCSI FIRMWARE INTERRUPT STRU CTURE

the REACTIVATION entry point of the SCSI firmware. The WAIT FOR INTERRUPT (OPEN) status is usually given when a part icular TARGET is "threaded" to the MVME147 on the SCSI bus, and is slow in transitioning between information transfer phases. A bus phase interrupt brings the processor back to the SCSI firmware to finish the command execution that was temporarily slowed down by the TARGET.

For the WAIT FOR INTERRUPT (OPEN) status, the user may send a new command because the SCSI bus is free.

The second method of returning control involves the d irect br anch or jum p to the REACTIVATION entry point of the firmware. For all the statuses involved (WAIT TIME, MESSAGE RECEIVED, COMMAND RECEIVED), the MVME147 is the current SCSI bus initiator and the user may only service the current "thread".

The SCSI firmware was designed to operate in both interrupt and noninterrupt modes. When the user chooses the interrupt mode of operation, the WD33C93 interrupt is enabled at the level specified in command packet in the MVME147 interrupt handler. Vector number $45 is used by the WD33C93 f or the SCSI bus interrupts and the SCSI firmware initializes vector offset $114 to point to the SCSI firmware interrupt handler.

Whenever processor control is passed to the SCSI firmware interrupt handler, the MC68030 interrupt mask must be at a level no lower than that specified in the command packet. As processor control is switched out of the interrupt handler, the MC68030 interrupt mask is still at the same level.

4-2

Introduction

This chapter covers information essential in writing a driver to support the SCSI interface in interrupt mode. A driver for non-interrupt mode is a trivial subset of the interrupt mode driver. The approach taken is to describe the major sections of a driver that need to be written. The examples shown have been extracted from the VERSAdos SCSI driver, and are dependent on the driver interface to the VERSAdos operating system. For this interface, see Figure 5-1. For details of the interaction between the driver and the SCSI firmware, see Figure 5-2.

Any driver that communicates to the SCSI firmware starts by building (for single callers) a command packet in memory and calling the command entry point SCSI_CMD in the MVME147Bug. The address of the packet is contained in register A2.

Access to the six SCSI entry points is provided through the use of a jump table located within the beginning of the MVME147 debug monitor. The jump table entry points and their SCSI firmware functions are shown in the following list.

WRITING A DRIVER

SCSI_CMD SCSI_ACTV

SCSI_INT SCSI_FUN

SCSI_CA SCSI_RTE

Interrupts from the SCSI controller chip are through vector $45 (offset $114). Interrupts from the MVME147 SCSI DMA channel are through vector $46 (offset $118). The self interrupts from the MVME147 SCSI firmware use the vector $4B (offset $12C) to return control to SCSI firmware. The S CSI firmware sets these vectors to point to its interrupt entry point.

EQU $FFFE077C SCSI command entry. EQU $FFFE0782 SCSI command

reactivation entry.

EQU $FFFE0788 SCSI interrupt entry. EQU $FFFE078E FUNNEL command

entry. EQU $FFFE0794 Come-again entry . EQU $FFFE079A RTE entry.

WRITING A DRIVER

Return from the SCSI firmware to the driver is done through the vector supplied in the packet. The VERSAdos driver uses vector $4E (offset $138), and tape driver uses vector $4D (offset $134). These vectors must be initialized to point to a driver routine which handles the return. Refer to the Interface Rules for the SCSI Firmware section in this chapter for details on the return.

The SCSI firmware can accept six commands (average) per peripheral device. A busy error may be returned if too many commands are received for a device depending on the firmware current activities. Until one command has been completed, or abnormally terminated, no other command may be dispatched to the firmware. Commands to any other device may be issued after a "wait for interrupt (open)" ($02) intermediate status, or final status is returned from the SCSI firmware to the driver. For more information, refer to the Interface Rules for the SCSI Firmware section in this chapter.

Figure 5-1. SCSI Disk Driver Interface to VERSAdos

Figure 5-2. SCSI Disk Driver

Building the Packet

Chapter 2 provides the details necessary to build the command packet. After the packet has been built, it needs to be passed to the SCSI firmware.

Passing Commands to the SCSI Firmware

Passing control from the driver to the SCSI firmware can be do ne by j umping directly to the firmware from the driver. The return from the firmware back to the driver is through the vector supplied within the packet. Because the SCSI firmware can only accept six commands (average) for each device, you may need to do internal queuing if more commands need to be sent to a particular device.

Interface Rules for the SCSI Firmware

SCSI firmware may be called by single or multiple callers. A single caller to the SCSI firmware is a driver or a server that provides a

single return path from the firmware. In other words, a single SCSI return routine handles the status codes that the firmware passes. This definition does not imply that only one return routine is used for interpretin g status

5-2

Interface Rules for the SCSI Firmware

information; it does imply that only one routine handles the exit conditions dictated by bit 13 of the second word in the user packet (also known as the status word).

Multiple callers of the SCSI firmware are separate, independent drivers that handle SCSI returns without knowledge of other drivers/callers. This definition implies that more than one routine handles the exit conditions dictated by bit 13 of the first returned status word.

Interface Rules for Multiple Callers

Rule 1: COMMANDS ARE SENT TO FUNNEL

COMMAND ENTRY.

You send a command by loading the address of your packet in address register A2 and jumping to the FUNNEL command entry ($FFFE078E). The system must be in supervisory mode and the interrupt mask must the equal specified in the packet.

A command may be sent to the FUNNEL command entry almost any time, except as noted below.

A command may not be sent to the FUNNEL command entry point after the following returned intermediate status codes have been received (all intermediate status codes have bit 15 set):

1. ($xx04) Message received.

2. ($xx06) Command received (TARGET role) The above intermediate status codes are returned when a TARGET is threaded

and on the SCSI bus. These cases require entry to the RTE entry to complete the firmware-specified actions. Refer to Rule 2 below.

You may send a command to the FUNNEL command entry on all final status returns except:

Final status with bit 13 clear, indicating that an RTE is to be executed. (In this case, a new command may be sent by entering the firmware at the SCSI_RTE entry, $FFFE079A. Register A3 must remain intact.)

IMPLEMENTATION NOTE: Your interface driver or interface server usually has the command entry processing and command status processing decoupled. In other words, commands are sent to the SCSI firmware as a result of a subroutine call or as a result of a TRAP call to your driver or server.

5-3

WRITING A DRIVER

Command status processing is the result of a firmware return to the vector specified in the command packet. If this decoupling exists, the command entry execution can only occur if the processor is not tied up performing SCSI firmware functions or performing command status functions. That is, for the processor to execute the command entry functions, it cannot be at the same time executing command status functions. At the time the command is passed to the driver/server, the command entry code may go ahead and send the command to the firmware without hesitation.

Rule 2: INTERMEDIATE RETURNS MUST

REENTER AT REACTIVATION OR RTE ENTRY.

The following is a list of intermediate status return codes provided by the firmware (intermediate status codes have bit 15 set):

$xx02: The SCSI firmware returns this code if a disconnect occurred

on the bus or if firmware is waiting for SCSI controller chip to interrupt. Again, no action is required for this status other than servicing the RTE (13) bit.

5-4

$xx04: A message was received by the firmware that was either

uninterpretable or was received in TARGET role. You are responsible for the interpretation of extended messages in initiator and TARGET roles. The MVME147 is still threaded on the bus when this status is passed to the user. The user routine is responsible for interpreting the message and for the proper return point. If bit 13 of the returned status is set, the return is to the reactivation entry ($FFFE0782), and if bit 13 of the returned status is clear, the return is to the RTE entry ($FFFE079A) and register A3 must remain intact. For this status, an RTE is only "remembered for the next exit". If the RTE bit is 0 with this status, an RTE is required. If this condition occurs, address register A3 is pointing to a register list.

$xx06: In TARGET role, a command has been received and the SCSI

firmware stored in the command table. The firmware returns this intermediate status to alert you to service the command and to return to either the reactivation entry ($FFFE0782) no

Interface Rules for the SCSI Firmware

RTE required, or the RTE entry ($FFFE079A) RTE required as status code $xx04 above. This intermediate status only happens when the TARGET role is enabled.

CAUTION

Care must be taken not to modify the contents of

Rule 3: ALL FINAL RETURNS MUST EXIT (THE

DRIVER) PROPERLY THROUGH RTE, COME-

AGAIN, OR REACTIVATION.

All final status code returns use bits 15 through 13 of the status word in the packet (second word of the user’ s packet) to tell you about the condition of the SCSI firmware and of the SCSI bus.

BIT 15: FINAL=(0)/INTERMEDIATE=(1) STATUS bit. For all final

status return codes, this bit is 0.

BIT 14: ADDITIONAL STATUS bit. For all final status returns, if this

bit is 1, additional status may be found in the additional status area (CT +$74). If this bit is 0, no additional status is provided.

BIT 13: RTE bit. If this bit is a 0, an RTE is required to finish an

interrupt thread. When this bit is 0, A3 contains a pointer to a register save area where D0 through D7 and A0 through A6 were saved. If the RTE is to be executed, the registers in the register save area must first be restored. If this bit is a 1, no RTE is to be executed.

The return mechanism on the final status co des only involve bits 13 of the user status word (packet word 2). You MUST follow the priority scheme below if you wish to interface to the SCSI firmware successfully.

RETURN CODE:

5-5

WRITING A DRIVER

IF BIT 13 IS SET THEN RETURN TO THE CALLER OF YOUR CODE THROUGH (command 1. AN RTS IF HE CALLED YOU WITH A BSR/JSR thread) 2. AN RTE IF HE CALLED YOU WITH A TRAP THAT REQUIRES AN RTE RETURN. ELSE: (bit 13 is clear)

1. RESTORE THE REGISTER SET POINTED TO BY A3. (interrupt 2. SOMEHOW PERFORM THE RTE REQUIRED BY THE FIRMWARE. thread) SOME OPERATING SYSTEMS HAVE A COMMON INTERRUPT HANDLER THAT PERFORMS ALL RETURNS FROM INTERRUPT PROCESSING. IN THIS CASE, EXECUTE THE COMMON INTERRUPT HANDLER TO PERFORM THE RTE. IF THE PARTICULAR OPERATING SYSTEM OF THE USER DOES NOT HAVE A COMMON INTERRUPT HANDLER, EXECUTE THE RTE INSTRUCTION. ENDIF.

5-6

END OF RETURN CODE.

As can be seen from the return algorithm, the preprocessed packet and the packet queuing process is done through the software interrupt (vector $4B) set by the firmware and is transparent from user tasks. Here are the reasons:

1. A preprocessed packet has already run through the firmware BLDPCKT

(build

command packet) module and is ready to communicate with the initiator

or TARGET

on the SCSI bus. The only reason that this command packet did not make

to the bus was that a selection or a reselection interrupt of the MVME147

beat

this packet to the bus. It is imperative that this packet run next.

2. A packet was sent to the FUNNEL entry for processing. Because the bus

and

device wait queue was occupied at the instant the packet arrived, the

Interface Rules for the SCSI Firmware

FUNNEL module queued the request and returned to you with a $A002 intermediate status code. In order for this packet to resume processing, the firmware sets the software interrupt to reenter the interrupt entry point ($FFFE0788).

3. The RTE condition receives third priority because if an RTE instruction was effectively executed before the command pending or before the queued commands were serviced, the command pending or the queued commands would never be serviced.

EXCEPTIONS TO THE RETURN ALGORITHM:

Rule 4. THE SCSI FIRMWARE CAN ONL Y

PROCESS SIX COMMAND PACKETS, IN AVERAGE, PER

PERIPHERAL DEVICE AT A TIME.

The firmware has a 64 entry funnel queue for all the devices (1 per device in average).

An index of the SCSI peripheral devices exists in the firmware in order to provide threading information for command overlap on the SCSI bus. This index is called the attach table. One entry per peripheral device provides pointers to the user packets, and command tables. In each command table, there is a 4 entry private wait queue for each device (each one points to a command packet). When a peripheral device is given a command packet, its respective entry in the attach table is marked "busy". If you send a command packet for a peripheral device that is marked "busy", a busy error is returned if both private wait queue and FUNNEL queue are full. You may not see this busy

5-7

WRITING A DRIVER

error because if a subsequent command is queued in the FUNNEL queue or the wait queue, no busy error is given.

In average, a device could have one packet in FUNNEL queue, four packets in wait queue, and an active command in attach table.

INTERFACE RULE SUMMARY FOR SCSI FIRMWARE USERS WITH MULTIPLE CALLERS:

A typical system with multiple callers may have the following interfaces:

1. Disk driver: Handles all requests for SCSI disks.

2. Tape driver: Handles all requests for SCSI tapes.

3. TARGET LUN 0 service handler: Services requests for SCSI device level for the MVME147 as a TARGET and services logical unit 0 of the MVME147 TARGET.

5-8

4. TARGET LUN 1 service handler: Services requests for logical unit 1 of the MVME147 TARGET.

5. TARGET LUN 2 service handler: Services requests for logical unit 2 of the MVME147 TARGET.

6. TARGET LUN 3 service handler: Services requests for logical unit 3 of the MVME147 TARGET.

7. TARGET LUN 4 service handler: Services requests for logical unit 4 of the MVME147 TARGET.

8. TARGET LUN 5 service handler: Services requests for logical unit 5 of the MVME147 TARGET.

Interface Rules for the SCSI Firmware

9. TARGET LUN 6 service handler: Services requests for logical unit 6 of the MVME147 TARGET.

10. TARGET LUN 7 service handler: Services requests for logical unit 7 of the MVME147 TARGET.

The summary below is intended to help users who have multiple callers to the SCSI firmware.

1. INTERMEDIATE RETURNS:

xx02: PERFORM AN RTE (HOWEVER REQUIRED) IF BIT 13 OF

THE RETURNED STATUS WORD IS 0 OR RETURN TO THE CALLER OF THE DRIVER/SERVER BY THE APPROPRIATE METHOD. E.G. IF THE DRIVER IS CALLED BY A BSR, AN RTS SHOULD BE USED.

xx04: AFTER APPROPRIATE PROCESS, RETURN TO THE

REACTIVATION ENTRY ($FFFE0782) IF BIT 13 OF THE RETURNED STATUS WORD IS 1, OR RETURN TO THE RTE ENTRY ($FFFE079A) IF BIT 13 OF THE RETURNED STATUS WORD IS 0.

xx06: SAME RULE AS FOR xx04 ABOVE.

xx08: INITIATOR DATA RECEIVED, USER MUST INTERPRET

THEN CONTINUE WITH NEW TARGET SEQUENCE PACKET BY FOLLOWING SAME RULE AS FOR xx04 ABOVE.

5-9

WRITING A DRIVER

xx08: SIMILAR TO xx08 ABOVE, ONLY THE DATA RECEIVED

HAS SOME PARITY ERROR OCCURRED.

2. FINAL RETURNS:

ST ATUS WORD BIT 13: IF CLEAR, SOMEHOW RESTORE

(RTE) SET AND PERFORM AN RTE. IF SET,

THE FIRST RETURN FROM THE SCSI FIRM-

WARE (COMMAND THREAD) AND THE USER

SHOULD RETURN TO WHOMEVER CALLED

THE DRIVER (RTS, ETC.).

SAMPLE RETURN CODE FOR ONE OF MANY CALLERS OF THE SCSI FIRMWARE:

Note

5-10

It may not be clear to the casual reader that address register A3 is not modified in this return code. If an RTE is to be executed, address register A3 points to the register save area. The subroutine RESTORE_REG uses register A3 to restore the registers D0 through D7 and A0 through A6. If a reentry to the RTE entry is executed, the address register A3 must remain intact.

(SCSI_RET: is the label that is pointed to by the vector provided in the user packet.)

SCSI_RET:

Interface Rules for the SCSI Firmware

MOVE.W 2(A2),D0 STATUS WORD TO D0. BTST #15,D0 FINAL/INTERMEDIATE STATUS? BEQ FINALSTAT IF 0, THE RETURN IS A FINAL ONE.

****************************************************************** ************

*THE FOLLOWING CODE CHECKS ALL ALLOWED INTERMEDIATE RETURN CODES. * CMP.B #$02,D0 WAITING FOR AN INTERRUPT? (BUS CLEAR) IF <EQ> THEN BRA RET_OUT NO NEW COMMANDS TO SEND BECAUSE NO QUEUING NECESSARY

* FOR MULTIPLE CALLERS, THE SCSI FIRMWARE QUEUES COMMANDS WHEN THE BUS IS * BUSY. * BECAUSE OF THIS REASON, NO COMMAND QUEUING IS NECESSARY IN THE DRIVER. IF * THERE IS NO QUEUING IN THE DRIVER, THE DRIVER WILL NOT HAVE A NEW COMMAND * TO SEND WHENEVER AN INTERMEDIATE OR FINAL RETURN OCCURS. THE COMMANDS ARE * ALWAYS SENT AS THEY ARRIVE TO THE DRIVER. * ’RET_INT’ is the user’s code to handle the return from interrupt process. ENDI

CMP.B #$04,D0 MESSAGE INTERPRETATION? IF <EQ> THEN BSR INTERPRET INTERPRET IS A MESSAGE INTERPRETATION ROUTINE BRA RET_INT ENDI

CMP.B #$06,D0 COMMAND RECEIVED FOR THE TARGET? IF <EQ> THEN BSR SERVCMD SERVCMD IS TARGET ROLE COMMAND SERVICE ROUTINE BRA RET_INT ENDI

5-11

WRITING A DRIVER

****************************************************************** ************ ** * THE CODE BELOW HANDLES FINAL RETURN CODES.

FINALSTAT:

BSR POSTSTAT POSTSTAT IS A SUBROUTINE THAT POSTS FINAL STATUS

* POSTSTAT RETURNS THE Z BIT=1 IF STATUS IS O.K.

****************************************************************** ************ ** * THE CODE BELOW IS A COMMON EXIT CODE FOR THIS DRIVER.

RET_OUT

BTST #13,D0 RTE REQUIRED? IF <EQ> THEN BSR RESTORE _REG A3 IS THE INPUT TO THIS REGISTER REST ORE ROUTINE RTE EXECUTE THE RTE FOR THE SCSI FIRMWARE ENDI

* THERE ARE ONLY TWO WAYS TO ACTUALLY ’EXIT’ THIS CALLER ROUTINE. * 1. IS TO EXIT VIA THE EXECUTION OF AN RTE. (A TASK WAS INTE RRUPTED BY THE * SCSI BUS AND THE EXECUTION OF THE RTE WILL RESUME THAT TASK.) * * 2. A ROUTINE CALLED THIS DRIVER BY A SUBROUTINE CALL. IT IS RETURNED TO WITH * THE EXECUTION OF AN RTS. * * ALL OTHER ’EXITS’ GO BACK TO THE SCSI FIRMWARE (FOR THIS EXAMPLE).

RTS

5-12

Interface Rules for the SCSI Firmware

* RESTORE REGISTERS FOR SCSI ROUTINE

* The driver must restore the registers the SCSI firmware has used. * A3 is pointing to a list of the registers to restore. * The following code is for 68010 or newer processor a nd could be more * efficient if more advanced processor as 68020, 68030 is used.

* Entry: A3 = Pointer to register list of registers to * restore.

* Exit: Back to caller.

RESTORE_REG:

MOVE.L #14,D0 Number of longwords to move = 15. ADDA.L #60,A3 Start from bottom of register list. RSTRLOOP MOVE.L -(A3),-(SP) Store on the stack for MOVEM instruction. DBRA D0,RSTRLOOP

MOVEM.L (SP)+,D0-D7/A0-A6 Restore registers.

REST_OUT RTS

END ****************************************************************** ************

Interface Rules for a Single Caller

You can use the same rules as provided for multiple callers. By doing so, a second or third caller may later be added without the necessity of modifying the initial caller routine. By using the rules for multiple callers, a user also expects the firmware to do more work than would otherwise have to be don e

5-13

WRITING A DRIVER

by the driver -- specifically, command queuing. If you choose to follow the rules for multiple callers, the firmware queues command packets for you whenever the bus is busy.

For example, if a user of the SCSI interface only has disk applicati ons, only a SCSI disk driver for the particular operating system may need to be written. If the rules for multiple callers are used, then at a later time, a SCSI tape driver for the same operating system may be added without affecting the old disk driver (assuming that the tape driver returns are vectored through a different vector than the SCSI disk driver). Refer to the Interface Rules for Multiple Callers section in this chapter for details.

5-14

TARGET ROLE ROUTINES

Introduction

According to SCSI definitions, an initiator is an SCSI device that initiates a command on the bus to be executed by the TARGET; a TARGET is an SCSI device that is selected by an initiator and executes what is requested by the initiator. The MVME147 is capable of playing both the initiator and TARGET roles with the WD33C93 SCSI interface chip. Because most of the SCSI protocol is performed outside the WD33C93, the TARGET role routines of the MVME147 SCSI firmware provide the means of supporting command execution and message passing for the MVME147 operating as a processor device TARGET on the SCSI bus. As defined by the SCSI draft revisions 17 and earlier, only three commands for processor-type devices are considered standard; these are: SEND (0A), RECEIVE (08), and REQUEST SENSE (03). The contents of the data sent are not define d by SCSI standard and are totally interpretable by the user application. An entire decoding scheme could be built around the three basic commands for interprocessor communication over the SCSI bus.

MVME147 SCSI Firmware Background

The MVME147 SCSI firmware provides routines that supports initiator role on the SCSI bus. Execution of disk reads, writes, and formats are provided by read, write, and format packets, respectively. Another important support of SCSI execution is also provided by the custom SCSI sequence packets of the MVME147 firmware. With the custom SCSI sequence, you pass a pointer to a particular "script" (a sequence of information transfer phase codes) and a pointer to the data that supports this script to the firmware, along with the code for the custom SCSI sequence and also provides a re turn vector for status and processor control. With this particular interface, the firmware performs any sequence of SCSI information transfer phases that you require. The TARGET role routines provide the missing half for these custom SCSI sequences -- execution of scripts in the TARGET role.

The SCSI bus makes allowance for only eight SCSI devices. Each SCSI device is allowed to service eight peripheral devices. If all peripheral devices were present on the SCSI bus, there would be a maximum of 64. The MVME147 SCSI firmware developes a method of indexing the devices on the SCSI bus. This index is the "attach table", a table of 64 entries, each entry peculiar to a

TARGET ROLE ROUTINES

particular device on the SCSI bus. The indexing is accomplished b y simply splitting the 64 entries into 8 entries of 8 peripheral devices. Each block of eight devices corresponded to each SCSI device. The MVME147 is one of these SCSI devices. Seven other SCSI devices may be added to the SCSI bus to perform some application. As long as there is another SCSI device that can play the initiator role on the bus, then the MVME147 may also play the TARGET role on the bus. The eight entries under the SCSI device entry deal with TARGET support of eight peripheral devices. In other words, the SCSI firmware TARGET role routines allow support of eight peripheral devices associated with the MVME1 47.

The method of addressing these peripheral devices is through the concept of logical units. Because the MVME147 supports eight logical units on the SCSI bus, LUN 0 may be a printer, LUN 1 may be an RS-232C port, and LUNs 2 through 7 may be some I/O devices on the VMEbus (as an example). Each logical unit is independent of the other as far as the SCSI firmware is concerned. To keep this independent feature, each service module for each logical unit should provide a different return vector to the SCSI firmware.

SCSI Versus SASI Rules

As far as the SCSI firmware is concerned, a SCSI system is one that supports arbitration, reselection, and the message-out phase. Typically, a SASI system contains only one initiator and at least one TARGET. A SASI system with only one initiator and no reselection clearly does not require bus arbitration because only one SCSI device ever tries to acquire the bus. With these rules in place, it is clear that for the MVME14 7 to operate bo th as an initia tor and as a TARGET on the SCSI bus, you must have a SCSI system; one that supports arbitration, reselection, and the message-out phase. (The message-out phase is required for identification of reselectability after the selection phase and for identification of the peripheral logical unit immediately following reselection.) If the MVME147 is to operate only as a TARGET on the SCSI bus with on ly one initiator on the same bus, then you may use a SASI system with the MVME147 as a TARGET only.

MVME147 SCSI Firmware T ARGET Role Structure Requirements

The following sections describe the data structures required by the SCSI firmware for the TARGET role custom sequence packets. Refer to Chapter 2.

Custom Sequence Packet

Custom Sequence packets are detailed in Chapter 2.

6-2

Script

MVME147 SCSI Firmware TARGET Role Structure Requirements

Command Table pointer Script pointer Interrupt level 7 through 1 Return vector TARGET enable/TARGET sequence Control number = MVME147 level Peripheral device LUN (0 through 7)

Below are the TARGET role script codes for SCSI bus phases. $00 DISCONNECT

$04 COMMAND PHASE $08 DATA-OUT PHASE $0CDATA-IN PHASE $10 STATUS PHASE $14 MESSAGE-OUT PHASE $18 MESSAGE-IN PHASE $1CEND OF SCRIPT $20 TARGET WAIT, NO DISCONNECT ALLOWED $24 TARGET WAIT, DISCONNECT ALLOWED $28 TARGET WAIT, NO DISCONNECT, DATA RECEIVED $2CTARGET WAIT, DISCONNECT, DATA RECEIVED

Command Table

A command table is shown in the Initiator Role section in Chapter 2. Status/Control B yte

Link Pointer

Link (used in the TARGET module). Parity (implemented in the TARGET module). DMA (implemented in the TARGET module). CSCSI (check SCSI status). SG (implemented with DMA in the TARGET module). SYNC/ASYNC (implemented in the TARGET module).

Forward link pointer to the next command table (not used in the first release).

6-3

TARGET ROLE ROUTINES

Data Area Only one direction allowed per command. If multiple

directions of data transfer are required, linked commands could provide a solution.

Message-In Area (user defined)

For messages to be sent to the initiator.

Message-Out Area (user defined)

258 byte maximum for extended message for messages sent by initiator.

Command Count

The number of bytes command received in the command area.

Command Area(s)

Commands are stored in this 12-byte-maximum area.

Status Area This status byte is sent if the status phase is encountered in the

script.

Data Area Count

Data transfer count.

Data Area Pointer

Pointer to the data area described below. DATA-IN: to the initiator, DATA- OUT: from the initiator.

Message-In Area Count

Number of message bytes to be sent to the initiator.

Message-In Area Pointer

Pointer to the message-in area described below. Messages sent to the initiator.

Message-Out Area Count (not used)

Message-Out Area Pointer

Pointer to the message-out area described below. Messages received from the initiator.

Enabling TARGET Role

1. Prepare a custom sequence packet as described in the TARGET Enable Custom Sequence Packet section in Chapter 2, with the code of TARGET

6-4

Note

Enabling TARGET Role

enable (word $0E = $C000), and with the following data structures reserved for TARGET role service.

a. Command Table (384 bytes )

During the TARGET role, when the TARGET ena ble packet is issued to the firmware, neither the custom command packet nor the command table shall be deallocated because firmware uses both areas for subsequent TARGET service .

b. Message-out area (the SCSI standard allows for a 258-byte extended

message)

In SCSI terms, all transfer direct ions are referen ced to the initiator. For exa mple, the data ou t phase is a d ata phas e for data OUT of the initiator and INTO the TARGET. Therefore, the message-out area mentioned above is for message STORAGE from the initiator to the TARGET.

c. Take over the return vector specified in the packet of 1. above. Put the

service routine address in the vector.

d. Load address register A2 with the address of the custom sequence packet

described in 1. above.

e. Enter the SCSI firmware through the FUNNEL entry point ($ FFFE078E) at

interrupt level 2. (For a description of the FUNNEL module, refer to the SCSI Firmware Entry Points section in Chapter 1.

f. Examine the returned final status for a code of $xx17. This is a signal that

the firmware has acknowledged the enable packet and the initiator command has been received. (This status may be preceded by a $A002 if the bus is occupied at the time that the enable packet was sent to the firmware.)

g. The service of the TARGET LUN is now interrupt-driven by the initiator.

A selection interrupt causes the firmware to examine enabled TARGET LUNs and load commands and/or messages into the designated areas for service. If a command is received for an enabled TARGET logical unit, then the firmware returns to you with either a $xx17 final status (SCSI mode) or an intermediate status of $xx06 (SASI mode or initiator not supporting disconnection), indicating that the CDB has been loaded into

6-5

TARGET ROLE ROUTINES

the user command table. The service of this command is provided by you. This service is provided by a custom SCSI sequence -- TARGET sequence, which is described in the next section.

IMPLEMENTATION NOTE: The TARGET LUN is deciphered from the identify message sent immediately after the selection phase. If the LUN identified during this phase is not enabled by you, the firmware rejects the message (by sending the MESSAGE REJECT message) and then disconnect from the bus. If an identify message is rejected, it is a signal that some other LUN on this MVME147 TARGET address must be enabled, otherwise the SCSI firmware would not have responded to the selection in the first place. If a selection interrupt is ignored because the TARGET role was not enabled in the firmware, the firmware ignores the interrupt after the SEL signal is removed from the bus. In any case, if this happens, the SCSI bus is tied up unless the initiator times out and gives up by removing its signals from the bus.

Servicing the TARGET Requests

After a particular LUN is enabled for TARGET role, a selection interrupt begins the interrupt-driven service for TARGET role and the TARGET role stays enabled until the system is reinitialized. (The selection interrupt enable through the WD33C93 is turned on and only reinitialization turns the interrupt enable off. Disabling the selection interrupt is accomplish ed b y clearing the select enable register in the WD33C93 and/or turning the PCC SCSI interrupt enable off through the module control register.) Issuing a board reset also disables TARGET role on the MVME147.

6-6

If TARGET role is enabled, a selection of the MVME147 causes the firmware to respond to the selection by asserting the BSY signal. The follo wing sequence is typical of SCSI rules.

If the ATN line is asserted with SEL, the firmware takes the SCSI bus to the message-out phase and reads the message. The firmware then takes the S CSI bus to the command phase, reads the command ( 6, 10, or 12 bytes), and stores the command count and the command in the command table. If the received message is "identify" and if the identified LUN has been enabled, the firmware continues and save the messages and command in command table area. No command interpretation is done in the firmware; this job is left for the user application. If disconnect is allowed then next phase directed by the firmware is the message-in phase: the DISCONNECT message is sent. Then a bus disconnect is performed by releasing the BSY signal. The first TARGET role

Servicing the TARGET Requests

service performed by the firmware is now complete. Finishing some housekeeping, the firmware returns to the user service routine for the selected LUN and gives it a final status code of $xx17.

If initiator is not supporting disconnect, no message-in phase and the TARGET role returns an intermediate status $xx06 for command received.

If firmware is not enabled, the target role will response to ’inquiry’, ’request sense’ commands with some meaningful data. Also, it will return "Not Ready" to ’test unit ready’, ’send’, and ’send diagnostic’ commands. To all other commands before target enabled, an ’Illegal request’ will be returned.

Now comes your turn to perform the required services. The CDB that was received by the TARGET role firmware during the

command phase was stored in the command buffer that was allocated when you issued the TARGET enable packet to the firmware. (The command table pointer points to this command buffer; refer to the TARGET Enable Custom Sequence Packet section in Chapter 2, words $08 and $0A -- command table pointer.) You may wish to service the processor device standard commands SEND ($0A) and RECEIVE ($08). The service of commands is totally application driven. The SEND and RECEIVE commands are probably sufficient to establish processor communication over the SCSI bus. Following is an example of each service. "Example"

Example: Servicing the SEND command through the TARGET sequence firmware packet.

STEP 1: Command Interpretation

Below is the CDB for a SEND command.

bit.....7...6...5...4...3...2...1...0...

byte 0 : 0 0 0 0 1 0 1 0 (OP CODE) byte 1 : l u n - - - - - (LUN|reserved) byte 2 : Transfer length (M S byte) (Transfer length) byte 3 : Transfer length (middle byte) (Transfer length) byte 4 : Transfer length (L S byte) (Transfer length) byte 5 : v u - - - - f l (control byte)

6-7

TARGET ROLE ROUTINES

v u = vendor unique

- = reserved f= flag l = link

The operation code of $0A is for the SEND command. The LUN should match the logical unit for the MVME147 TARGET. The transfer length tells you how many bytes are going to be exchanged during the data-out phase.

The flag and link bits are handled by the firmware and you only have to load a "INTERMEDIATE STATUS/GOOD STATUS" if the link bit was set and a "GOOD STATUS" if the link bit was clear. If the link bit is set, you load a "LINKED COMMAND COMPLETE" message into the message-in buffer. If both the link and flag bits are set, you load a "LINKED COMMAND COMPLETE WITH FLAG" message into the message-in buffer. If neither the link nor the flag bits are set, you should load a "COMMAND COMPLETE" message-into the message-in buffer. (The status byte is part of the command table -- word $14. The message-in buffer is pointed to by words $20 and $22 of the command table.) (Link and flag features not supported on the first release of the TARGET module.)

STEP 2: Script Preparation

The SEND command requires the following script:

$08 : DATA-OUT PHASE $10 : STATUS PHASE $18 : MESSAGE-IN PHASE $1C : END OF T A RGET SCRIPT

Note

The SCSI firmware automatically performs the arbitration and reselection of the disconnected initiator. The IDENTIFY message is also automatically sent to the disconnected initiator, therefore, the initial message-in phase should not be in the script for a SEND command.

6-8

Servicing the TARGET Requests

STEP 3: Data Preparation

a. Decode the transfer length from the command descriptor block and load

this length into the command table words $16 and $18 -- data length.

b. Decode the link bit and store the status to be sent to the initiator during the

status phase into the STATUS word (MSB) of the command table -- word $64, even byte.

c. Decode the link and flag bits and store the proper message to be presented

during the message-in phase into the message-in buffer (pointed to by words $20 and $22 of the command table).

d. Create a TARGET sequence custom SCSI sequence packet as described in

the TARGET Sequence Custom Sequence Packet section in Chapter 2. This packet should contain a pointer to the script described above and to the command table that was created or used. (You may wish to use the same command table that was provided for the T ARGET enable call to the SCSI firmware.)

STEP 4: Call the SCSI Firmware

Point address register A2 to the packet created in Step 3d. above and jump into the SCSI firmware through the FUNNEL command entry.

Example: Servicing the RECEIVE command through the TARGET sequence firmware packet.

STEP 1: Command Interpretation

Below is the CDB for a RECEIVE command.

bit.....7...6...5...4...3...2...1...0...

byte 0 : 0 0 0 0 1 0 0 0 (OP CODE) byte 1 : l u n - - - - - (LUN|reserved) byte 2 : Transfer length (M S byte) (Transfer length) byte 3 : Transfer length (middle byte) (Transfer length) byte 4 : Transfer length (L S byte) (Transfer length) byte 5 : v u - - - - f l (control byte)

6-9

TARGET ROLE ROUTINES

v u = vendor unique

- = reserved f= flag l = link

The operation code of $08 is for the RECEIVE command. The LUN should match the logical unit for the MVME147 TARGET. The transfer length tells you how many bytes are going to be exchanged during the data-out phase. The flag and link bits should be treated in the same manner as for the SEND command example above. (Not supported on the first release.)

STEP 2: Script Preparation

The RECEIVE command requires the following script:

$0C : DA TA-IN PHASE $10 : STATUS PHASE $18 : MESSAGE-IN PHASE $1C : END OF T A RGET SCRIPT

Note

6-10

STEP 3: Data Preparation

a. Decode the transfer length from the CDB and load this length into the

command table words $16 and $18 -- data length.

b. Decode the link bit and store the status to be sent to the initiator during the

status phase into the STATUS word (MSB) of the comman d table -- word $64, even byte.

Servicing the TARGET Requests

c. Decode the link and flag bits and store the proper message to be presented

during the message-in phase into the message-in buffer (pointed to by words $20 and $22 of the command table).

d. Create a TARGET sequence custom SCSI sequence packet as described in

STEP 4: Call the SCSI firmware

Point address register A2 to the packet created in Step 3d above and jump into the SCSI firmware through the FUNNEL command entry.

After the proper service script and command table have been prepared by the user, a second custom SCSI sequence -- TARGET sequence packet must be issued to the firmware. This packet is intended to service the command that was just received. A script is passed to the firmware to be executed immediately following the reselection of the disconnected initiator. The firmware automatically performs the message-in phase with the identify message to reestablish the disconnected thread. This information transfer phase (message-in) should NOT be in the script.

The phases are performed as instructed by the script until a "$1C=FINISHED" is encountered. This is the signal for the firmware to either disconnect from the bus or to begin service of the next part of a linked command. The link information is passed to the firmware through the con trol byte of the CDB. If the link bit is set, the firmware makes the transition to the command phase, stores the received command and command count into the command table, makes the transition to the message-in phase, and issues a disconnect message followed by a SCSI bus disconnect. Some housekeeping later, the firmware returns to the user service routine with a final status of $xx19, stating that a command has been received following the completion of the ea rlier command serviced in a link. The service process then repeats.

If the serviced command has not been linked and a disconnect has been performed instead, the firmware cleans up some details and returns to the user service routine with a $xx18 final status.

A custom SCSI sequence -- TARGET sequence is shown in the TARGET Sequence Custom Packet section in Chapter 2.

6-11

TARGET ROLE ROUTINES

6-12

Introduction

Command packets for the SCSI functions are listed in Table 7-1. The command packets are described in detail in the following paragraphs.

SCSI

FUNCTION CODE DESCRIPTION

$00 Read (use new read, refer to $70 below) $04 Write (use new write, refer to $74 below) $08 Attach (use new di sk attach, refer to

$0C Detach (all devices) $10 Format (with/without defect list) $14 Assign Alternate Sector $18 Reserved $1C Custom SCSI Sequence (refer to Chapter 2) $20 SCSI Bus Reset $24 SCSI Controller Reset $28 Tape Attach (use new tap e attach, refer

$2C Erase $30 Rewind $34 Read Block Limits $38 Space (blocks, filemarks, sequential

$3C Write Filemarks $40 Verify CRC $44 Tape Mode Select $48 Tape Mode Sense

SCSI PACKETS

Table 7-1. SCSI Functions

$78 below)

to $6C below)

filemarks, end of data)

SCSI PACKET S

Table 7-2. SCSI Functions (cont’d)

SCSI

FUNCTION CODE DESCRIPTION

$4C Reserved $50 Inquiry $54 Load/Unload $58 Recover Buffer Data $5C Request Sense Data $60 Check Status $64 Reserve Device $68 Release Device $6C New Tape Attach $70 New Read (disk and tape) $74 New Write (disk and tape) $78 New Disk Attach $7C Open (read of first blocks of a device)

Read/Write Packet

For common command set refer to Appendix A. DISK. Commands sent to the controller are: Read ($28), and Write ($2A). For a read or write function, the maximum number of bytes that can be

transferred in a single call is 16Mb. If you need more, the command must be broken up into several calls. For controller type 13, the command control field can turn on/off the cache within the drive. If th e drive currently has cach e in the opposite state as the command control field cache bit, a mode select of page 38 is sent to the controller to turn on/off the cache prior to the read/write command.

TAPE. Commands sent to the controller are: read ($08) and write ($0A). A tape read or write operation starts at the current position and must be in the

correct mode (refer to the appropriate controller manual). To write, the controller must be in general mode or write mode. General mode occurs after a tape positioning command that does not read the tape data (space-to-end-ofrecorded-media). Also, the controller can be at Beginning Of Tape (BOT),

7-2

Read/Write Packet

space-to-end-of-recorded-media, or write command. To read, the controller must be at BOT or following a space-blocks, space-filemarks, or read command.

The command control field gives the user the ability to read forward or reverse (if supported by drive) and the ability to suppress ill eg al length indication (if supported by drive).

DISK and TAPE. For scatter/gather operation, a non-zero value in the scatter/gather count

indicates the memory and scatter/gather address field is the address of the scatter/gather table. The number of sectors field must be filled in and is also used to calculate the total byte count.

The details of a read/write packet are shown below. New Packet

Even Byte \ Odd Byte \

FC B8 74 30 +$00 Controller LUN Device LUN +$02 Status Byte 0 Status Byte 1 (No te 1) +$04 Memory Address (MSW) (Note 2) +$06 Memory Address (LSW) (Note 2) +$08 Sector Number (MSW) +$0A Sector Number (LSW) +$0C Number of Sectors to Transfer (MSW) +$0E Number of Sectors to Transfer (LSW) +$10 Scatter/Gather Count +$12 0000 +$14 Command Control Function Code (70, 74) +$16 Interrupt Level Vector Number +$18 Status Byte 2 Status Byte 3 (No te 1)

7-3

SCSI PACKET S

$00 00000xxx Controller logical unit

number

$01 00000xxx Device logical unit

number

$02 xxxxxxxx Status from SCSI

firmware (byte 0) (Note 1)

$03 xxxxxxxx Status from SCSI

firmware (byte 1) (Note 1)

$04 xxxxxxxx xxxxxxxx Memory Address

(MSW)/scatter/gathe r

table address if scatter/gath er co unt > 0

$06 xxxxxxxx xxxxxxxx Memory Address

(LSW)/scatter/gather table address if

scatter/gath er co unt > 0

$08 xxxxxxxx xxxxxxxx Sector Number

(MSW) $0A xxxxxxxx xxxxxxxx Sector Number (LSW) $0C xxxxxxxx xxxxxxxx Number of sectors to

transfer/number

of logical

blocks/bytes to

transfer (MSW)

(Note 7) $0E xxxxxxxx xxxxxxxx Number of sectors to

transfer/number

of logical

blocks/bytes to

transfer (LSW)

(Note 7) $10 xxxxxxxx xxxxxxxx Scatter/gather count,

number of entries

7-4

Read/Write Packet

in SG table, if zero,

SG is disabled $12 00000000 00000000 Reserved $14 xxxxxxxx Command Control

0....... Cache ON for type 13

controller only

1....... Cache OFF for type

13 controller only

.0...... Tape read forward for

tape devices that support this

.1...... Tape re ad rev erse for

tape devices that support this

..0..... Tape do not suppress

illegal length indication for tape

devices that support this

..1..... Tape suppress illegal

length indication for tape devices that

support this

$15 xxxxxxxx SCSI function ($70 =

Read, $74 = Write)

$16 00000xxx Interrupt level (7

through 0) (0 = polled mode)

(Notes 3, 5)

$17 xxxxxxxx Vector number to use

upon return (Notes 4, 5)

$18 xxxxxxxx Status from SCSI

firmware (byte 2) (Note 1)

$19 xxxxxxxx Status from SCSI

firmware (byte 3) (Note 1)

7-5

SCSI PACKET S

NOTE S:

Old Packet Supported for Compatibility

Even Byte \ Odd Byte \

1. Refe r to Chapter 3.

2. Refer to the following scatter/gather table form at.

3. The interrupt level of this firmware can be from level 0 to 7. It should be kept the same throughout the firmware execution; i.e., when the user has chosen a specific interrupt level, it must not be changed until there is no outstanding command.

4. The return vector should point to the user return routine at all times for the proper return path.

5. Because both the interrupt vector and the return vector use the Vector Base Register (VBR) to locate the proper address to resume the operation, the VBR should not be changed if there are any outstanding SCSI commands.

6. During scatter/gather operation, no automatic RETRY is performed by SCSI firmwar e and the sc atte r/gath er table contents co uld be modi fied by the firmware when the command is completed.

7. For tape, if the previous tape attach had both physical bytes per block and logical bytes per block = 0 (variable block size). This field is number of bytes to transfe r.

FC B8 74 30

+$00 Controller LUN Device LUN +$02 Status Byte 0 Status Byte 1 (No te 1) +$04 Memory Address (MSW) (Note 2) +$06 Memory Address (LSW) (Note 2) +$08 Sector Number (MSW) +$0A Sector Number (LSW) +$0C Number of Sectors to Transfer +$0E 0000 +$10 Scatter/Gather Count

7-6

Read/Write Packet

+$12 0000 +$14 Command Control Function Code (00, 04) +$16 Interrupt Level Vector Number +$18 Status Byte 2 Status Byte 3 (No te 1)

$00 00000xxx Controller logical unit

number

$01 00000xxx Device logical unit

number

$02 xxxxxxxx Status from SCSI

firmware (byte 0) (Note 1)

$03 xxxxxxxx Status from SCSI

firmware (byte 1) (Note 1)

$04 xxxxxxxx xxxxxxxx Memory Address

(MSW)/scatter/gathe r

table address if scatter/gath er co unt > 0

$06 xxxxxxxx xxxxxxxx Memory Address

(LSW)/scatter/gather table address if

scatter/gath er co unt > 0

$08 xxxxxxxx xxxxxxxx Sector Number

(MSW) $0A xxxxxxxx xxxxxxxx Sector Number (LSW) $0C xxxxxxxx xxxxxxxx Number of sectors to

transfer/number

of logical

blocks/bytes to

transfer $0E 00000000 00000000 Reserved $10 xxxxxxxx xxxxxxxx Scatter/gather count,

number of entries

7-7

SCSI PACKET S

in SG table, if zero,

SG is disabled $12 00000000 00000000 Reserved $14 xxxxxxxx Command Control

0....... Cache ON for type 13

controller only

1....... Cache OFF for type

13 controller only

.0...... Tape read forward for

tape devices that support this

.1...... Tape re ad rev erse for

tape devices that support this

..0..... Tape do not suppress

illegal length indication for tape

devices that support this

..1..... Tape suppress illegal

length indication for tape devices that

support this

$15 xxxxxxxx SCSI function ($00 =

Read, $04 = Write)

$16 00000xxx Interrupt level (7

through 0) (0 = polled mode)

(Notes 3, 5)

$17 xxxxxxxx Vector number to use

upon return (Notes 4, 5)

$18 xxxxxxxx Status from SCSI

firmware (byte 2) (Note 1)

$19 xxxxxxxx Status from SCSI

firmware (byte 3) (Note 1)

7-8

Read/Write Packet

NOTE

1. Refe r to Chapter 3.

2. Refer to the following scatter/gather table form at.

4. The return vector should point to the user return routine at all times for the proper return path.

6. During scatter/gather operation, no automatic RETRY is performed by SCSI firmwar e and the sc atte r/gath er table contents co uld be modi fied by the firmware when the command is completed.

DMA Scatter/Gather Table Entry

Each scatter/gather table entry has two longwords: first one is DMA memory address, second is control/byte count.

310

DMA MEMORY ADD RESS (32 -BIT)

X0000101XXXX

XXXX

|function code (3 bits) 1 = link to next entryFor example $5 is 0 = no link, last entryused here (supervisory data space)

XXXX XXXX

7-9

SCSI PACKET S

NOTES:

There may be any number of scatter/gather entries. The scatter/gather table must be in local MVME147 RAM (the DMA

channel does not table walk offboard RAM). Table address must be longword aligned.

Attach/Detach Packet (all devices)

For common command set refer to Appendix A. The following SCSI commands are executed during an attach:

COMMAND

DEVICE NAME COMMAND NOTES

SCSI Wincheste r

Reserve device $16 Executed on attach if reserve-

Release device $17 Executed on detach if reserve-

Test unit ready $00 Checks whether the selected

Mode sense $1A To check the block size. If the

CONTROLLER

on-attach/release-on- deta ch b it is set in packet. A reserve device command is sent to the controller. A reserve device command can be used in a multi-initiator SCSI en vironment to reserve the device.

on-attach/release-on- detac h b it is set in packet. A release device command is sent to the controller and the firmware clears an internal attach flag. A release device command can be used in a multi-initiator SCSI environment to release the device.

device is ready.

block size in the packet is different than the controller/drive setting, all reads/writes are blocked an d an "attach error" is returned.

7-10

Attach/Detach Packet (all devices)

COMMAND

DEVICE NAME COMMAND NOTES

TAPE Rewind $01 A rewin d command is sent (2.0

Reserve device $16 Executed on attach if reserve-

Release device $17 Executed on detach if reserve-

Mode select $15 This command configures the

Test unit ready $00 Checks whether the selected

CONTROLLER

firmware and later) because many tape devices require the tape to be at BOT to send a mode select command.

on-attach/release-on- detac h b it is set in packet. A release device command is sent to the controller, and the firmware clears an internal attach flag. A release device command can be used in a multi-initiator SCSI environment to release the device.

controller for operat-ional parameters.

device is ready.

An attach is required before any other commands may be sent to the SCSI firmware (except custom SCSI sequence or Bus Reset).

An attach call initializes the SCSI firmware pointers and internal flags. A RAM work area is used by SCSI firmware for building internal pointers and also contains the command sent to the SCSI controller. The RAM work a rea should not be reallocated until the device is detached or reset.

7-11

SCSI PACKET S

Some SCSI controllers return a "check" status on the first command sent to them after power-up or reset. The SCSI firmware retries the command if the controller returns "unit attention" request sense information and if you put a number that was one or greater into the retry field in the attach packet. Otherwise, the request-sense data is returned to you. You can then retry the command.

The first table below shows the details of an attach/detach packet for disk. The second table shows the details of a attach packet for streaming tape. A third table details the 384-byte ($180-byte) work area specified in the attach packet and used for all subsequent commands. The work area is normally not examined by you except when the "additional status" bit is set (refer to the packet status codes in Chapter 3). On most operations involving data transfer (except scatter/gather) in which DMA is used, the "sector number in error", "transfer address", and "command error word" can be used to assist error handling.

New Packet

Even Byte \ Odd Byte \

FC B8 74 30 +$00 Controller LUN Device LUN +$02 Status Byte 0 Status Byte 1 (No te 1) +$04 0 0 Step Rate +$06 0 0 Number of Heads +$08 Number of Cylinders +$0A Precompens ation Cylinder +$0C Logical Sectors per Track +$0E 0000 +$10 SCSI Disk Attributes +$12 Controller Type Drive Type +$14 0 0 Function Code (7 8) +$16 Interrupt Level Vector Number +$18 Status Byte 2 Status Byte 3 (No te 1) +$1A 0 0 Retry Count +$1C Physical Bytes per Block

7-12

Attach/Detach Packet (all devices)

+$1E +$20 Pointer RAM

Work Area (MSW)

Pointer RAM Work Area (LSW)

+$28 Alt Sectors per Zone No. Alt Cyls to Reserve

$00 00000xxx Controller logical unit

$01 00000xxx Device logical unit

$02 xxxxxxxx Status from SCSI

$03 xxxxxxxx Status from SCSI

$04 00000000 Reserved $05 xxxxxxxx Step Rate -- number

$06 00000000 Reserved $07 xxxxxxxx Number of heads on

$08 xxxxxxxx xxxxxxxx Number of cylinders

$0A xxxxxxxx xxxxxxxx Precompensation

$0C xxxxxxxx xxxxxxxx Logical sectors per

$0E 00000000 00000000 Reserved $10 xxxxxxxx xxxxxxxx SCSI drive attributes

+$24 Logical Bytes per

Block

+$22

+$26

number (SCSI address 0-7)

number (0-7)

firmware (byte 0) (Note 1)

firmware (byte 1) (Note 1)

of 40 intervals per step (a value of 0

defaults to 6 ms)

drive

on drive

cylinder

track, physic al = this plus alternate sectors

per zone if zone = track

7-13

SCSI PACKET S

........ .......0 FM encoding, single

density

........ .......1 MFM encoding,

double density

........ ......0. Single track density

(media TP I = ½ drive TPI,

double step)

........ ......1. Double track density

(media TPI = drive TPI)

........ ........ Reserved

........ ....0... 250K bits/sec data

rate (5¼ inch)

........ ....1... 500K bits/sec data

rate (8 inch)

........ ...0.... Floppy media

........ ...1.... Rigid media

........ ..0..... No reserve on attach;

no release on detach

........ ..1..... Reserve on attach;

release on detach

........ .0...... Non-buffered seeks

........ .1...... Buffered seeks

........ 0....... Standard IBM format,

256b sectors are 128 in track 0

........ 1....... Non-standard; all

sectors same size, even

track 0

.......0 ........ Soft-sectored media

.......1 ........ Hard-s ec tored media

......0. ........ Fixed media drive

......1. ........ Removable media

drive

........ ........ Reserved

....0... ........ Zone = track

....1... ........ Zone = cylinder

7-14

Attach/Detach Packet (all devices)

$12 xxxxxxxx Controller type (refer

to controller type table)

$13 00000000 Drive type (0 =

random access drive) $14 00000000 Reserved $15 xxxx1x00 SCSI function ($08 =

attach, $78 = new

attach,

$0C = detach) $16 000000xx Interrupt level (7

through 0) (0 = polled

mode) $17 xxxxxxxx Vector number to use

upon return $18 xxxxxxxx Status from SCSI

firmware (byte 2)

(Note 1) $19 xxxxxxxx Status from SCSI

firmware (byte 3)

(Note 1) $1A 00000000 Reserved $1B xxxxxxxx Retry count: number

of SCSI commands

(if this is set to 0, the

firmware disables

correction and turns

off retries in the

controller. Also, the

firmware does not

automatically retry

the SCSI command

except

"unit attention" and

"not diagnostics".) $1C xxxxxxxx xxxxxxxx Sector/block size in

bytes (MSW) $1E xxxxxxxx xxxxxxxx Sector/block size in

bytes (LSW)

7-15

SCSI PACKET S

$20 xxxxxxxx xxxxxxxx Address of 384-byte

SCSI RAM area (MSW)

$22 xxxxxxxx xxxxxxxx Address of 384-byte

SCSI RAM area (LSW)

This SCSI RAM work area cannot be

deallocated or moved except after a detach

or reset command. The firmware uses this

area for the SCSI CDB and local pointers

and variables.

$24 xxxxxxxx xxxxxxxx Logical bytes per

block must be an

$26 xxxxxxxx xxxxxxxx integer multiple of

physical bytes per block and if track 0 is

half the density of the rest of the disk, then

the sectors per track field must be an even

value. This prevents a

half sector overrun of data.

$28 xxxxxxxx Defines the number

of alternate sectors per

zone to reserve for alternates. The zone can

be described as either a track or a cylinder,

as specified by bit 11 of the SCSI drive

7-16

Attach/Detach Packet (all devices)

attributes (byte offset

$10). $29 xxxxxxxx Alternate cylinders

defines the number of

alternate cylinders

per disk that are to be

reserved at the end of

the disk for

alternates.

NOTE:

1. Refer to Chapter 3.

Old Packet Supported for Compatibility

Even Byte \ Odd Byte \

FC B8 74 30 +$00 Controller LUN Device LUN +$02 Status Byte 0 Status Byte 1 (No te 1) +$04 0 0 Step Rate +$06 0 0 Number of Heads +$08 Number of Cylinders +$0A Precompens ation Cylinder +$0C Logical Sectors per Track +$0E 0000 +$10 SCSI Disk Attributes +$12 Controller Type Drive Type +$14 0 0 Function Code (08, 0C) +$16 Interrupt Level Vector Number +$18 Status Byte 2 Status Byte 3 (No te 1) +$1A 0 0 Retry Count +$1C Physical Bytes per Block +$1E Alt Sectors per Zone No. Alt Cyls to Reserve

7-17

SCSI PACKET S

+$20 RAM Work Area Address (MSW) +$22 RAM Work Area Address (LSW)

$00 00000xxx Controller logical unit

number (SCSI address 0-7)

$01 00000xxx Device logical unit

number (0-7)

$02 xxxxxxxx Status from SCSI

firmware (byte 0) (Note 1)

$03 xxxxxxxx Status from SCSI

firmware (byte 1)

(Note 1) $04 00000000 Reserved $05 xxxxxxxx Step Rate -- number

of 40 intervals per

step (a value of 0

defaults to 6 ms) $06 00000000 Reserved $07 xxxxxxxx Number of heads on

drive $08 xxxxxxxx xxxxxxxx Number of cylinders

on drive $0A xxxxxxxx xxxxxxxx Precompensation

cylinder $0C xxxxxxxx xxxxxxxx Logical sectors per

track, physic al = this

plus alternate sectors

per zone if zone =

track $0E 00000000 00000000 Reserved $10 xxxxxxxx xxxxxxxx SCSI drive attributes

........ .......0 FM encoding, single

density

........ .......1 MFM encoding,

double density

7-18

Attach/Detach Packet (all devices)

........ ......0. Single track density

(media TP I = ½ drive TPI,

double step)

........ ......1. Double track density

(media TPI = drive TPI)

........ ........ Reserved

........ ....0... 250K bits/sec data

rate (5¼ inch)

........ ....1... 500K bits/sec data

rate (8 inch)

........ ...0.... Floppy media

........ ...1.... Rigid media

........ ..0..... No reserve on attach;

no release on detach

........ ..1..... Reserve on attach;

release on detach

........ .0...... Non-buffered seeks

........ .1...... Buffered seeks

........ 0....... Standard IBM format,

256b sectors are 128 in track 0

........ 1....... Non-standard; all

sectors same size, even

track 0

.......0 ........ Soft-sectored media

.......1 ........ Hard-s ec tored media

......0. ........ Fixed media drive

......1. ........ Removable media

drive

........ ........ Reserved

....0... ........ Zone = track

....1... ........ Zone = cylinder

$12 xxxxxxxx Controller type (refer

to controller type table)

7-19

SCSI PACKET S

$13 00000000 Drive type (0 =

random access drive) $14 00000000 Reserved $15 xxxx1x00 SCSI function ($08 =

attach, $78 = new

attach,

$0C = detach) $16 000000xx Interrupt level (7

through 0) (0 = polled

mode) $17 xxxxxxxx Vector number to use

upon return $18 xxxxxxxx Status from SCSI

firmware (byte 2)

(Note 1) $19 xxxxxxxx Status from SCSI

firmware (byte 3)

(Note 1) $1A 00000000 Reserved $1B xxxxxxxx Retry count: number

of SCSI commands

(if this is set to 0, the

firmware disables

correction and turns

off retries in the

controller. Also, the

firmware does not

automatically retry

the SCSI command

except

"unit attention" and

"not diagnostics".) $1C xxxxxxxx xxxxxxxx Sector/block size in

bytes $1E xxxxxxxx Defines the number

of alternate sectors

per

zone to reserve for

alternates. The zone

can

7-20

Emerson MVME147 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Introduction

Features

GENERAL INFORMATION

Modes of Operation

MVME147 SCSI Firmware Entry Points

Equipment Supported

Related Documentation

Manual Terminology

Introduction

CUSTOM SCSI PACKETS

Initiator Role Custom Packet

TARGET Enable Custom Packet

TARGET Sequence Custom Packet

PACKET RETURN STATUS

Packet Return Status

SCSI Firmware Interrupt Structure

Introduction

WRITING A DRIVER

Building the Packet

Passing Commands to the SCSI Firmware

Interface Rules for the SCSI Firmware

Interface Rules for Multiple Callers

Interface Rules for a Single Caller

TARGET ROLE ROUTINES

Introduction

MVME147 SCSI Firmware Background

SCSI Versus SASI Rules

MVME147 SCSI Firmware T ARGET Role Structure Requirements

Custom Sequence Packet

Script

Command Table

Enabling TARGET Role

Servicing the TARGET Requests

Introduction

SCSI PACKETS

Read/Write Packet

DMA Scatter/Gather Table Entry

Attach/Detach Packet (all devices)