Freescale Semiconductor MPC5200 Application Note

Freescale Semiconductor

Application Note

MPC5200 ATA Interface

by: Martin Nykodym

Transportation Standard Products Group

AN3223

Rev. 0, 2/2006

1 Introduction

This application note describes initialization, general
rules, programming model and performance analysis for
the MPC5200 ATA interface, mainly from a software
perspective. The main focus is to help system architects
understand which mode under what circumstances is
optimal for the final product. Detailed software examples
can be found on the publicly available CD with sample
code for the MPC5200. The MPC5200B microcontroller
is based on an e300
instruction set.

The ATA interface is used to connect:

• Hard disks

•CD-ROMs

• DVDs

• Flash storage devices

The MPC5200 ATA interface is fully compatible with
AT A/AT API-4 specification (A T Attachment with Packet
Interface Extension, ANSI NCITS 317-1998) supporting
all three groups of modes:

1

core using the PowerPC

TM

Table of Contents

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2 ATA Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2.1 Electrical Characteristics . . . . . . . . . . . . . . . . 3

2.2 Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2.3 IO Cable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.4 Byte Ordering. . . . . . . . . . . . . . . . . . . . . . . . . 5

2.5 Register Addressing . . . . . . . . . . . . . . . . . . . 5

2.6 Sector Addressing . . . . . . . . . . . . . . . . . . . . . 6

2.7 ATA Programming Model . . . . . . . . . . . . . . . 6

2.8 Host Initialization . . . . . . . . . . . . . . . . . . . . . . 9

2.9 Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3 Performance Analysis . . . . . . . . . . . . . . . . . . . . . 14

4 Literature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Appendix A MPC5200 ATA Register Summary

1. e300, 603e, and G2LE are synonymous.

© Freescale Semiconductor, Inc., 2006. All rights reserved.

ATA Interface

• PIO (from PIO-0 to PIO-4) – up to 16.7 MBytes/sec

• Multiword DMA (from MDMA-0 to MDMA-2) – up to 16.7 MBytes/sec

• Ultra DMA (from UDMA-0 to UDMA-2) – up to 33 MBytes/sec

MPC5200 supports 27-bit and 48-bit LBA addressing on every device.

2ATA Interface

The MPC5200 ATA interface includes three groups of registers:

• AT A host registers – host configuration, timing values for all modes (from PIO, MDMA, UDMA)

• ATA FIFO registers – control ATA FIFO for DMA modes (MDMA, UDMA)

• ATA drive registers – access to the registers physically located on the ATA drive

Figure 1 illustrates basic components of the MPC5200 ATA interface internal to the MPC5200. Data

transfer is driven either by MPC5200 core (PIO) or by the BestComm DMA engine (MDMA, UDMA).
BestComm is designed to offload the MPC5200 core and can transfer data to/from different peripherals
simultaneously. The MPC5200 ATA interface is clocked by the IPBI clock of the MPC5200 processor
(66/132 MHz). MPC5200 acts as an ATA host and can control up to two ATA devices as defined in
ATA/ATAPI-4 specification. Pin ATA_ISOLATION of the MPC5200 (not defined as a signal by
ATA/ATAPI-4 spec) connects to the transceiver’s OE pin to control the direction (high = write to drive,
low = read from drive) of the transfer.

BestComm

(higher priority)

IPBI

(lower priority)

ATA device 0

(e.g. DVD drive)

MPC5200

ATA Rx/Tx FIFO

Interface

(MDMA/UDMA)

Arbiter

IPBI Interface

IPBI clock (66/132 MHz)

ATA 40-pin cable

(PIO)

ATA
Line

Drivers

3.3 V – 5 V

ATA Host Interface

ATA_ISOLATION

ATA device 1

(e.g. CompactFlash)

Figure 1. ATA Architecture

MPC5200 ATA Interface, Rev. 0

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ATA Interface

2.1 Electrical Characteristics

AT A is a vo ltage level interface and the table below defines the voltage levels fo r logical ones and zeroes
or input and output values.

Table 1. ATA DC Characteristics

Description Min Max

Driver sink current1

I

oL

I

V

V

V

V

NOTES:

1

IoL for DASP shall be 12 mA minimum to meet legacy timing and signal integrity.

2

IoH value at 400 mA is insufficient in the case of DMARQ that is typically pulled low by a 5.6 kW
resistor.

Driver source current

oH

Voltage input high (logical one) 2.0 Vdc —

iH

Voltage input low (logical zero) — 0.8 Vdc

iL

Voltage output high (IoH=-400 µA, logical one) 2.4 Vdc —

oH

Voltage output low (IoL= 12 mA, logical zero) — 0.5 Vdc

oL

2.2 Signals

ATA Signal ATA Acronym MPC5200 Pin Direction

Cable select CSEL — > 28

Chip select 0 CS0- ATA_CSB0 > 37

Chip select 1 CS1- ATA_CSB1 > 38

Data bus bit 0 DD0 ATA_DATA_0 <> 17

Data bus bit 1 DD1 ATA_DATA_1 <> 15

2

Table 2. ATA Signals

4mA —

400 µA—

40-Pin

ATA Cable

Data bus bit 2 DD2 ATA_DATA_2 <> 13

Data bus bit 3 DD3 ATA_DATA_3 <> 11

Data bus bit 4 DD4 ATA_DATA_4 <> 9

Data bus bit 5 DD5 ATA_DATA_5 <> 7

Data bus bit 6 DD6 ATA_DATA_6 <> 4

Data bus bit 7 DD7 ATA_DATA_7 <> 3

Data bus bit 8 DD8 ATA_DATA_8 <> 4

Data bus bit 9 DD9 ATA_DATA_9 <> 6

Data bus bit 10 DD10 ATA_DATA_10 <> 8

Data bus bit 11 DD11 ATA_DATA_11 <> 10

Data bus bit 12 DD12 ATA_DATA_12 <> 12

Data bus bit 13 DD13 ATA_DATA_13 <> 14

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ATA Interface

Table 2. ATA Signals (continued)

ATA Signal ATA Acronym MPC5200 Pin Direction

Data bus bit 14 DD13 ATA_DATA_14 <> 16

Data bus bit 15 DD14 ATA_DATA_15 <> 18

Device active or slave (Device 1)
present

Device address bit 0 DA0 ATA_SA_0 > 35

Device address bit 1 DA1 ATA_SA_1 > 33

Device address bit 2 DA2 ATA_SA_2 > 36

DMA acknowledge DMACK- ATA_DACK_B > 29

DMA request DMARQ ATA_DRQ < 21

Interrupt request INTRQ ATA_INTRQ < 31

I/O read
DMA ready during Ultra DMA data in
bursts
Data strobe during Ultra DMA data
out bursts

I/O ready
DMA ready during Ultra DMA data
out bursts
Data strobe during Ultra DMA data in
bursts

I/O write
Stop during Ultra DMA data bursts

Passed diagnostics
Cable assembly type identifier

DASP- — > 39

DIOR-

HDMARDY-

HSTROBE

IORDY-

DDMARDY-

DSTROBE

DIOW-

STOP

PDIAG­CBLID-

ATA _IO R _ B >

>
>

ATA_IOCHRDY <

<
<

ATA _ IO W _B >

>

-<>34

40-Pin

ATA Cable

25

27

23

Reset RESET- HRESET_B > 1

Ground GND 2,19,22,24,

26,

30,40

2.3 IO Cable

The cable specification impacts system integrity and the maximum length that shall be supported in any
application. Cable total length shall not exceed 0.46 m (18 in.). Cable capacitance shall not exceed 35 pF.
80-pin grounded cable helps to avoid problems with noise and inductance although 40-pin cable is
sufficient for modes up to UDMA-2 as in the ATA/ATAPI-4 spec. Also ATA/ATAPI-4 compliant
termination is a must; otherwise, CRC checksum error may randomly occur.

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ATA Interface

2.4 Byte Ordering

Assuming a block of data contains "n" bytes of information, the bytes are labeled Byte(0) through
Byte(n-1), where Byte(0) is the first byte of the block, and Byte(n-1) is the last byte of the block. Table 3
shows the order of the bytes on the ATA interface.

Table 3. ATA Byte Ordering

DD15DD14DD13DD12DD11DD10DD9DD8DD7DD6DD5DD4DD3DD2DD1DD

0

First transfer Byte (1) Byte (0)

Second transfer Byte (3) Byte (2)

...

Last transfer Byte (n-1) Byte (n-2)

2.5 Register Addressing

This section describes the generation of the actual address (CSn-, DAn) that is present on the physical A TA
interface to address an ATA drive register by means of operations on internal registers of the MPC5200.

Table 4 shows how internal registers are decoded to ATA bus operations.

Table 4. ATA Register Address/Chip Select Decoding

.

Addresses Functions

MPC5200

register

address

— 1 1 x x x Data bus high impedance Not used

— 1 0 0 x x Data bus high impedance Not used

— 1 0 1 0 x Data bus high impedance Not used

0x3A5C 1 0 1 1 0 Drive alternate status Drive device control

— 1 0 1 1 1 Obsolete Not used

0x3A60 0 1 0 0 0 Drive data Drive data

0x3A64 0 1 0 0 1 Drive error Drive features

0x3A68 0 1 0 1 0 Drive sector count Drive sector count

0x3A6c 0 1 0 1 1 Drive sector number Drive sector number

0x3A70 0 1 1 0 0 Drive cylinder low Drive cylinder low

0x3A74 0 1 1 0 1 Drive cylinder high Drive cylinder high

CS0- CS1- DA2 DA1 DA0

READ (DIOR-) WRITE (DIOW-)

Control Block Registers

Drive LBA bits 0-7* Drive LBA bits 0-7*

Drive LBA bits 8-15* Drive LBA bits 8-15*

Drive LBA bits 16-23* Drive LBA bits 16-23*

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MPC5200 ATA Interface, Rev. 0

ATA Interface

Table 4. ATA Register Address/Chip Select Decoding (continued)

0x3A78 0 1 1 1 0 Drive device/head Drive device/head

Drive LBA bits 24-27* Drive LBA bits 24-27*

0x3A7C 0 1 1 1 1 Drive device status Drive command

— 0 0 x x x Invalid address Invalid address

*Mapping of registers in LBA mode

2.6 Sector Addressing

The addressing of data sectors recorded on the device's media is performed by a logical sector address.
Two modes are supported:

• Cylinder/head/sector addressing (CHS)

• Logical block addressing (LBA)

The MPC5200 host system may select either CHS translation addressing or LBA addressing on a
command-by-command basis by using the LBA bit in the ATA drive device/head register. The LBA bit
must be set if the host uses LBA addressing mode. The MPC5200 allows 27-bit LBA addressing per
device.

2.7 ATA Programming Model

Figure 2 describes the typical structure and sequence of steps needed to initialize and issue ATA

commands for MPC5200.

MPC5200 ATA Interface, Rev. 0

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BestComm task loader

Download BestComm image

Set task priorities

Initialize BestComm variables

ATA Interface

ATA driver

Set cached ATA memory regions

Initialize ATA host (MPC5200)

Initialize ATA device

(e.g. hard disk, CD-ROM, DVD)

Execute ATA command

according specified protocol

can be restarted at any time

Figure 2. MPC5200 ATA Programming Model

A BestComm task loader is needed if there is some peripheral requiring DMA transfer over the FIFOs
to/from a peripheral (ATA MDMA/UDMA, Ethernet, LocalPlus, PCI, etc.). The BestComm image is
downloaded and initialized only once, right after booting, due to the static content of the BestComm image
(image means BestComm binary firmware). The BestComm image acts as a server that serves clients
(peripheral software drivers).

It is recommended to start with the software examples published on the sample code CD. These software
examples include a set of already “pre-cooked” BestComm tasks that handle all required peripherals via
the BestComm C-API (BAPI). The system integrator needs to recompile all drivers in the case of any
change in the image. This guarantees compatible versions for both BestComm firmware and software
drivers.

Figure 3 documents the structure for the MDMA/UDMA data transfer.

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MPC5200 ATA Interface, Rev. 0

ATA Interface

Data transfer driven
by BestComm

ATA level shifters

ATA host interface

ATA Rx/Tx FIFO

BestComm

BestComm image in

MPC5200 SRAM

ATA task

ATA cable

MDMA/UDMA data

MPC5200

ATA device

(e.g., DVD drive)

Peripheral FIFOs

Embedded computer

Set of “pre-cooked”
tasks

BestComm C-API

Set of peripheral
drivers and their

ATA data

buffers

Application 1

(e.g., DVD player)

SDR/DDR memory

ATA software driver

Application 2

(e.g., MP3 player)

data buffers

Figure 3. MDMA/UDMA BestComm Driven Data Transfer

The BestComm C-API is not resident software. It is a piece of software statically linked to the driver that
includes a set of standardized function calls.

MPC5200 ATA Interface, Rev. 0

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ATA Interface

The following steps should be used to set up the cache for ATA memory buffer regions:

• Set DBAT registers and enable data cache.2 (See Programming Environments Manual for 32-Bit
Implementations of the PowerPC Architecture for details.)

• Set XLB priorities in the XLB arbiter master priority register and enable XLB priorities in the
arbiter master priority enable register.

3

(See the XLB Arbiter chapter in the MPC5200 User’s

Manual for details.)

• Set window address, size and snooping policy in the XLB arbiter snoop window register and
enable snooping in the XLB arbiter configuration register.

4

(See the XLB Arbiter chapter in the

MPC5200 User’s Manual for details.)

2.8 Host Initialization

The MPC5200 ATA host initialization covers three different groups of steps:

1. ATA common initialization
— Set ATA chip select in GPS port configuration register

— Read IPBI clock speed in CDM configuration register (66 or 132 MHz) needed for timing

registers)
— Enable ATA clock in CDM clock enable register
— Install ATA interrupt handler and BestComm interrupt handler for MDMA/UDMA modes
— Enable ATA/BestComm interrupt

2. PIO initialization (BestComm not needed for PIO modes)
— Set PIO timing registers

5

— Enable drive interrupt (to pass to CPU in PIO modes) in ATA host configuration register

(IE bit)

— Enable IORDY in ATA host configuration register (for PIO-3 and above)

3. MDMA/UDMA initialization
— Set either MDMA or UDMA timing registers

2.9 Protocols

ATA commands written into the ATA drive device command register are grouped into different classes
according to the protocols. The protocols define the command execution flow . The command classes with
their associated protocols are defined in Table 5.

The following sections directly document the commands instead of providing a detailed general
description for each protocol. The addressing scheme and the handling of some of the commands are
usually provided in linkable libraries by operating system vendors; therefore, the following description is

2. Usually entire memory cached, initialized by bootloader

3. Initialized by bootloader

4. Set up by driver

5. Bootloader sets up IPBI clock speed, peripheral drivers should read status only

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MPC5200 ATA Interface, Rev. 0

ATA Interface

intended to help software engineers understand how to initialize the MPC5200 ATA interface and how to
execute standard commands.

NOTE

Flash storage media require a different set of commands that are not
described in this application note. It is recommended to first read the
identify table for each ATA device found on the ATA bus. It contains
specific information needed to handle the device properly . For protocol and
identification information details, see Attachment with Packet Interface
Extension, ANSI NCITS 317-1998.

Table 5. ATA Protocols

Protocol Commands

Device reset protocol —

Execute device diagnostic

protocol

Device selection protocol —

PIO data-in command protocol

CFA TRANSLATE SECTOR, IDENTIFY DEVICE, IDENTIFY PACKET DEVICE, READ BUFFER,
READ MULTIPLE, READ SECTOR(S), SMART READ DATA

.

—

PIO data-out command protocol CFA WRITE MULTIPLE WITHOUT ERASE, CFA WRITE SECTORS WITHOUT ERASE,

DOWNLOAD MICROCODE, SECURITY DISABLE PASSWORD, SECURITY ERASE UNIT,
SECURITY SET PASSWORD, SECURITY UNLOCK, WRITE BUFFER, WRITE MULTIPLE,
WRITE SECTOR(S)

Non-data command protocol

DMA command protocol READ DMA, WRITE DMA

Packet non-data and PIO data

command protocol

Packet DMA command protocol PACKET, SERVICE

Read/write DMA queued

command protocol

CFA ERASE SECTORS, CFA REQUEST EXTENDED ERROR CODE, CHECK POWER MODE,
FLUSH CACHE, GET MEDIA STATUS IDLE, IDLE IMMEDIATE, INITIALIZE DEVICE
PARAMETERS, MEDIA EJECT, MEDIA LOCK, MEDIA UNLOCK, NOP, READ NATIVE MAX
ADDRESS, READ VERIFY SECTOR(S, SECURITY ERASE PREPARE, SECURITY FREEZE
LOCK SEEK, SET FEATURES, SET MAX ADDRESS, SET MULTIPLE MODE SLEEP, SMART
DISABLE OPERATION, SMART ENABLE/DISABLE AUTOSAVE, SMART ENABLE
OPERATION, SMART EXECU TE OFFLINE IMMEDIATE, SMART RETURN STATUS,
STANDBY, STANDBY IMMEDIATE

PACKET, SERVICE

READ DMA QUEUED, SERVICE, WRITE DMA QUEUED

2.9.1 Drive Initialization

2.9.1.1 PIO Initialization Protocol Steps

1. Select drive according to device selection protocol in ATA/ATAPI-4 spec:

6

a) Wait for BSY

6. BSY - The Drive Busy bit indicates that the device is busy.

7. DRQ - The Data Request bit indicates that the device is ready to transfer a word of data between the host and the device.

=0 and DRQ7 = 0 in ATA drive alternate status register

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b) Write ATA drive device/head register with appropriate DEV8 bit and LBA bit
c) Wait 400 ns
d) Wait for BSY=0 and DRQ = 0 in ATA drive alternate status register

2. Enable

INTRQ in ATA drive device control register (nIEN bit)

3. Set PIO mode in ATA drive features register according to non-data command protocol in
ATA/ATAPI-4 spec:

a) Set PIO mode in ATA drive sector count register
b) Write
c) Write
d) Wait for ATA interrupt – indicates that the device has accepted the

SET TRANSFER mode into ATA drive features register
SET FEATURES command into ATA drive device command register

SET FEATURES command

2.9.1.2 MDMA/UDMA Initialization Protocol Steps

1. Select drive according to device selection protocol in ATA/ATAPI-4 spec:
a) Wait for BSY=0 and DRQ = 0 in ATA drive alternate status register
b) Write ATA drive device/head register with appropriate DEV bit and LBA bit
c) Wait 400 ns
d) Wait for BSY=0 and DRQ = 0 in ATA drive alternate status register

2. Enable

3. Set MDMA/UDMA mode in ATA drive features register according to non-data command
protocol in ATA/ATAPI-4 spec:

a) Set MDMA/UDMA mode in ATA drive sector count register
b) Write
c) Write
d) Wait for ATA interrupt – indicates that the device has accepted the

INTRQ in ATA drive device control register (nIEN bit)

SET TRANSFER MODE into ATA drive features register
SET FEATURES command into ATA drive device command register

SET FEATURES command

ATA Interface

8. DEV - The Device Selection bit in ATA drive device/head register specifies which device is selected, 0 or 1.

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MPC5200 ATA Interface, Rev. 0

ATA Interface

2.9.2 PIO Data Read

2.9.2.1 PIO Data in Command Protocol Steps

1. Select drive according to device selection protocol in ATA/ATAPI-4 spec:
a) Wait for BSY=0 and DRQ = 0 in ATA drive alternate status register
b) Write ATA drive device/head register with appropriate DEV bit and LBA bit
c) Wait 400 ns
d) Wait for BSY=0 and DRQ = 0 in ATA drive alternate status register

2. Write ATA drive cylinder low register, AT A drive cylinder high register, A TA drive sector number
register, ATA drive sector count register

3. Write

4. Wait 400 ns

5. Wait for ATA interrupt – indicates that the data is ready for reading by host

6. Read (sector_count × sector_size) 16-bit ATA data words from ATA drive data register driven

READ SECTOR(S) command into ATA drive device command register

either by core or Bestcomm. In the case of Bestcomm when snooping is not used, cache needs to
be invalidated first

2.9.3 PIO Data Write

2.9.3.1 PIO Data Out Command Protocol Steps

1. Select drive according to device selection protocol in ATA/ATAPI-4 spec:
a) Wait for BSY=0 and DRQ = 0 in ATA drive alternate status register
b) Write ATA drive device/head register with appropriate DEV bit and LBA bit
c) Wait 400 ns
d) Wait for BSY=0 and DRQ = 0 in ATA drive alternate status register

2. Write ATA drive cylinder low register, AT A drive cylinder high register, A TA drive sector number
register, ATA drive sector count register

3. Write

4. Wait 400 ns

5. Wait for BSY=0 and DRQ = 1 in ATA drive alternate status register

6. Write (sector_count × sector_size) 16-bit A TA data words to A TA drive data register, driven either

7. Wait for ATA interrupt – indicates that the data has been written by the device

WRITE SECTOR(S) command into ATA drive device command register

by core or Bestcomm. In the case of Bestcomm when snooping is not used, cache needs to be
flushed first (entire write buffer)

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ATA Interface

2.9.4 DMA Data Read

2.9.4.1 DMA Command Protocol Steps

1. Select drive according to the device selection protocol in ATA/ATAPI-4 spec:
a) Wait for BSY=0 and DRQ = 0 in ATA drive alternate status register
b) Write ATA drive device/head register with appropriate DEV bit and LBA bit
c) Wait 400 ns
d) Wait for BSY=0 and DRQ = 0 in ATA drive alternate status register

2. If snooping is not used, cache needs to be invalidated

3. Initialize and start BestComm ATA task

4. Set ATA FIFO alarm and granularity in ATA Rx/Tx FIFO alarm register, ATA Rx/Tx FIFO
control register

5. Set FIFO Reset bit (FR) in ATA drive device command register when the direction is switched
from Tx to Rx

6. Clear FIFO Reset bit (FR) in ATA drive device command register*

7. Set FIFO Flush in Rx Mode bit (FE) and Read bit (READ) in ATA drive device command
register*

8. If UDMA, set UDMA bit (UDAMA) in ATA drive device command register. Clear it for
MDMA*

9. Set Drive Interrupt bit (IE) in ATA drive device command register*

NOTE

This could be done just by one command.

10. Wait 400 ns

11. Wait for BSY=0 and DRQ = 0 in ATA drive alternate status register

12. Write ATA drive cylinder low register, AT A drive cylinder high register , ATA drive sector number
register, ATA drive sector count register

13. Wait 400 ns

14. Wait for BSY=0 and DRQ = 0 in ATA drive alternate status register

15. Write

READ DMA command into ATA drive device command register

16. Wait for BestComm interrupt – indicates all data moved from ATA Rx FIFO to the RAM

2.9.5 DMA Data Write

2.9.5.1 DMA Command Protocol Steps

1. Select drive according to device selection protocol in ATA/ATAPI-4 spec:
a) Wait for BSY=0 and DRQ = 0 in ATA drive alternate status register
b) Write ATA drive device/head register with appropriate DEV bit and LBA bit
c) Wait 400 ns
d) Wait for BSY=0 and DRQ = 0 in ATA drive alternate status register

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MPC5200 ATA Interface, Rev. 0

Performance Analysis

2. If snooping is not used, cache needs to be flushed (entire write buffer)

3. Initialize and start BestComm ATA task

4. Set ATA FIFO alarm and granularity in ATA Rx/Tx FIFO alarm register, ATA Rx/Tx FIFO
control register

5. Set Write bit (WRITE) in ATA drive device command register*

6. If UDMA, set UDMA bit (UDAMA) in ATA drive device command register. Clear it for
MDMA*

7. Set Drive Interrupt (IE) bit in ATA drive device command register*

NOTE

This could be done just by one command.

8. Wait 400ns

9. Wait for BSY=0 and DRQ = 0 in ATA drive alternate status register

10. Write ATA drive cylinder low register, AT A drive cylinder high register , ATA drive sector number
register, ATA drive sector count register

11. Write

WRITE DMA command into ATA drive device command register

12. Wait for ATA interrupt – indicates that the data has been written by the device

2.9.6 Interrupt Handler

In the interrupt service routine, the first action is to clear the lower part of the ATA drive device command
register by writing a logical zero (bits HUT, FR, FE, IE, UDAMA, READ, WRITE). The pending ATA
drive interrupt is cleared by reading of the ATA drive device sstatus register as it is specified in the
ATA/ATAPI-4 specification.

3 Performance Analysis

Table 6 documents the maximum data throughput for all possible ATA modes. Of course, it is a theoretical

maximum throughput that, in reality, is never achieved. The real final result depends on the following:

• Device response delay – Average seek time for hard disks is a few milliseconds; therefore, some
host-based cache would be essential for applications like video players where large and
continuous streams of data need to be read from the device. This kind of host-based cache is
usually implemented as filesystem cache

• Sustained data rate – Devices like hard disks have limited speed at which physical data is read.
This number can be found in the device data sheet.

• Mode dependent delay

— Standby mode – The ATA device goes to the standby mode when the standby timer expires.

The interface is capable of accepting commands while waiting for the spindle to reach
operating speed. Delay is roughly hundreds of milliseconds

— Idle mode – See technical documentation for the ATA device.

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Performance Analysis

• Device fragmentation delay – If the device is highly defragmented, using the look-ahead feature9
does not help. This is a typical problem of hard disks or Flash storage devices. DVDs and CDs
always have contiguous blocks of data.

• MPC5200 timing granularity – The MPC5200 ATA interface is clocked by the IPBI clock
(66/132 MHz). The ATA/ATAPI-4 specification defines minimum values for cycle time, setup
time, and hold time. Minimum values for timing registers are specified in IPBI clock cycles and
need to be rounded up; therefore, the best result are achieved with finer granularity . (For example,
the IPBI clock 132 MHz is measured on the logic analyzer, 31.5 MBytes/sec, for UDMA-2.)
Compare this with the maximum theoretical throughput in Table 6.

Table 6. ATA Maximum Data Throughput

Mode

PIO-0 3.3 core core/Bestcomm

PIO-1 5.2 core core/Bestcomm

PIO-2 8.3 core core/Bestcomm

PIO-3 11.1 core core/Bestcomm

PIO-4 16.7 core core/Bestcomm

MDMA-0 4.2 core BestComm

MDMA-1 13.3 core BestComm

MDMA-2 16.7 core BestComm

UDMA-0 16.7 core BestComm

UDMA-1 25 core BestComm

UDMA-2 33 core BestComm

Max.Rate

[MBytes/Sec]

MPC5200 ATA

Initialization

Driven By

MPC5200 ATA

Data Transfer

Driven By

ATA performance can be optimized by:

• Reading/writing of the maximum number of sectors per single ATA command (see Figure 4
Regular hard disk defragmentation is essential

• Enabling of special features in the ATA device—look-ahead, write cache, etc. First, they need to
be checked in the identify table to see if supported and then enabled by the

SET FEATURES

command

10

).

• Using IPBI 132 MHz as described above

• Utilizing Bestcomm which can drive read/write in PIO mode to offload the core

9. Look-ahead read allows reading consequent sectors into the device cache. ATA host reads data from device cache. The size
of cache is vendor/type dependent, which can be found in the device documentation

10.Normalized results are measured by writing/reading 1 MB data to/from the same LBA address for IBM DBCA-203240 hard
disk with disabled drive cache. It could be different for other ATA devices. Check maximum number of sectors per single command
in the device identify table (usually up to 16 sectors per single command supported).

Freescale Semiconductor 15

MPC5200 ATA Interface, Rev. 0

Performance Analysis

3.0

2.5

2.0

1.5

1.0

normalized throughput

0.5

0.0

1.000 1.000

4

1.455

8

1.833

1.923

16 sectors per single command

2.535

UDMA-2 write

UDMA-2 read

Figure 4. ATA Relative Throughput Improvement

System throughput is a result of the speed of the peripheral and the final integration—typically in OSs. For
a properly defragmented ATA device, it is considered bad programming style if the MPC5200 ATA host
reads or writes only a small number of sectors per single ATA command. In this case, the ATA software
driver and its interrupt handler could consume significant amounts of core time. The AT A software driver
can block anything running with lower priority in the system (see Table 7).

11

In some cases in OSs, such

bad application implementation can degrade final ATA throughput by ~50% .

Table 7. System Throughput

.

ATA Mo de

UDMA-2

Sectors Per Single

Command

115

460

16 240

Time Between Two ATA

Interrupts

µs

µs

µs

Looking at Table 7, the question arises as to why the throughput improvement indicated in Figure 4 is not
as expected. The answer is simple; it is writing/reading the same LBA address with the look-ahead/write
cache feature disabled. The time needed to read data from the interface is much smaller (microseconds)
than the average seek time (milliseconds).

Static memory allocation for the ATA software driver is recommended.
Although not described in the MPC5200 User’s Manual, the MPC5200 ATA interface is capable of

UDMA-4 66 MBytes/sec mode. The programming model is the same as for UDMA-2. The impact of all
the above possible performance considerations is more visible because of higher speed.

11.Reading subsequent sectors from hard disk with enabled look-ahead feature, the worst scenario for MPC5200 core load

MPC5200 ATA Interface, Rev. 0

Freescale Semiconductor16

4 Literature

• MPC5200UM, MPC5200 User’s Manual (www.freescale.com)

• MPCFPE32B, Programming Environments Manual for 32-Bit Implementations of the PowerPC
Architecture) (www.freescale.com)

• G2CORERM, G2 Core Reference Manual (www.freescale.com)

• ATA/A TAPI-4, AT Attachment with Packet Interface Extension, ANSI NCITS 317–1998
(www.t13.org/technical/d98121r0.pdf)

• G2CORERM, G2 PowerPC Core Reference Manual (www.freescale.com)

Literature

Freescale Semiconductor 17

MPC5200 ATA Interface, Rev. 0

MPC5200 ATA Register Summary

Appendix A MPC5200 ATA Register Summary

Table A1. MPC5200 ATA Host Registers

Register Acronym

ATA host configuration ata_config MBAR+0x3A00 8

ATA host status ata_status MBAR+0x3A04 8

NOTES:

1

Acronyms use terminology such as ata.h in freely distributed software
examples.

1

Offset Size [Bits]

Table A2. MPC5200 ATA Timing Registers

Register Acronym

ATA PIO timing 1 ata_pio1 MBAR+0x3A08 32

ATA PIO timing 2 ata_pio2 MBAR+0x3A0C 32

ATA multiword DMA timing 1 ata_dma1 MBAR+0x3A10 32

ATA multiword DMA timing 2 ata_dma2 MBAR+0x3A14 32

ATA ultra DMA timing 1 ata_udma1 MBAR+0x3A18 32

ATA ultra DMA timing 2 ata_udma2 MBAR+0x3A1C 32

ATA ultra DMA timing 3 ata_udma3 MBAR+0x3A20 32

ATA ultra DMA timing 4 ata_udma4 MBAR+0x3A24 32

ATA ultra DMA timing 5 ata_udma5 MBAR+0x3A28 32

ATA share count ata_invalid MBAR+0x3A2C 32

NOTES:

1

Acronyms use terminology such as ata.h in freely distributed software
examples.

1

Offset Size [Bits]

Table A3. MPC5200 ATA FIFO Registers

Register Acronym

ATA Rx/Tx FIFO data word ata_fifo_data MBAR+0x3A3C 32

ATA Rx/Tx FIFO status ata_fifo_status MBAR+0x3A41 8

ATA Rx/Tx FIFO control ata_fifo_control MBAR+0x3A44 8

ATA Rx/Tx FIFO alarm ata_fifo_alarm MBAR+0x3A4A 16

ATA Rx/Tx FIFO read pointer ata_fifo_rdp MBAR+0x3A4E 16

ATA Rx/Tx FIFO write pointer ata_fifo_wrp MBAR+0x3A52 16

NOTES:

1

Acronyms use terminology such as ata.h in freely distributed software examples.

MPC5200 ATA Interface, Rev. 0

1

Offset Size [Bits]

Freescale Semiconductor18

Table A4. MPC5200 ATA Drive Registers

MPC5200 ATA Register Summary

Register Acronym

1

Offset Size [Bits] Mode

ATA drive device control ata_drive_ctrl MBAR+0x3A5C 8 write-only

ATA drive alternate status 8 read-only

ATA drive data ata_drive_data MBAR+0x3A60 16 R/W

ATA drive features ata_drive_ftr MBAR+0x3A64 8 write-only

ATA drive error 8 read-only

ATA drive sector count ata_drive_sc MBAR+0x3A68 8 R/W

ATA drive sector number ata_drive_sn MBAR+0x3A6C 8 R/W

ATA drive cylinder low ata_drive_cl MBAR+0x3A70 8 R/W

ATA drive cylinder high ata_drive_ch MBAR+0x3A74 8 R/W

ATA drive device/head ata_drive_dh MBAR+0x3A78 8 R/W

ATA drive device command ata_drive_cmd MBAR+0x3A7C 8 write-only

ATA drive device status 8 read-only

NOTES:

1

Acronyms use terminology such as ata.h in freely distributed software examples.

Freescale Semiconductor 19

MPC5200 ATA Interface, Rev. 0

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