AMD Geode™ GX Processor/
CS5535 Companion Device
GeodeROM Porting Guide
April 2006
Publication ID: 32430C
AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide
© 2006 Advanced Micro Devices, Inc. All rights reserved.
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respect to the accuracy or completeness of the contents of this publication and
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companies.
2 AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide
Contents 32430C
Contents
List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.0 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.2 Assumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.0 Model Specific Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.1 Example MSR Transaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.0 GeodeLink™ Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1 GeodeLink™ MSR Addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2 Descriptors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.0 Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.1 Processor Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.2 AMD Geode™ CS5535 Companion Device Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.3 Virtual System Architecture™ Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.4 PCI Bus Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.5 Miscellaneous Initializations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.0 Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
5.1 Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.0 Setup Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
7.0 Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Appendix A Support Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
A.1 Document Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide 3
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Contents
4 AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide
List of Figures 32430C
List of Figures
Figure 3-1. GeodeLink™ Architecture Topology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Figure 4-1. Clock Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Figure 7-1. GLIU Descriptor Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 7-2. CPU Core Cache Descriptors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 7-3. CPU Core Cache Region Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Figure 7-4. GeodeROM Flow - GX Processor/CS5535 Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide 5
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List of Figures
6 AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide
List of Tables 32430C
List of Tables
Table 4-1. Default Region Configuration Properties Bit Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Table 4-2. Diverse Device I/O Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide 7
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List of Tables
8 AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide
Overview 32430C
1.0Overview
1
1.1 Introduction
This document describes the changes needed for GeodeROM and other BIOSs to support the AMD Geode™ GX processor and the AMD Geode™ CS5535 companion device. GeodeROM requires modifications for hardware initialization and
specific implementations.
Each section targets the GeodeROM changes needed to support the GX processor/CS5535 device system. Where appropriate, the changes list the “Entry Conditions” that briefly describe the machine state required to execute that function, as
well as some pseudo code for implementing the changes.
For more information on GeodeROM, see the AMD Geode™ GeodeROM Functional Specification (publication ID 32087).
1.2 Assumption
The following assumption must be made clear during the design phase:
GeodeROM expects all memory has a serial presence detect (SPD) to determine characteristics for memory controller initialization. If a SPD is not present, GeodeROM outputs a POST code and halts, unless customizations have been made for
the platform.
AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide 9
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Assumption
10 AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide
Model Specific Registers 32430C
2.0Model Specific Registers
2
There are two ways to read or write Model Specific Registers (MSRs) in a Geode™ GX processor system. Software running on the processor can use the RDMSR and WRMSR instructions, and modules within the processor can use the
GeodeLink™ MSR transactions. The second method allows debug modules, such as the System Navigator from FS
Silicon Solutions), to program MSRs.
All MSRs are 64 bits wide. The MSR addresses are 32 bits, where each unique address refers to a 64-bit data quantity.
To communicate with modules on the GeodeLink interface, the address of that module must be known. Addresses are
obtained by either scanning the GeodeLink interface or having prior knowledge of the chip topology. This is discussed in
detail in Section 3.0 "GeodeLink™ Architecture" on page 13.
RDMSR:
Input
ECX - Address to read.
2
(First
Output
EDX:EAX - 64 bits data returned.
WRMSR:
Input
ECX - Address to write.
EDX:EAX - 64 bits data written.
Output
None.
2.1 Example MSR Transaction
Read and write extended CPUID registers.
This example will change the CPUID.
RDMSR:
Load MSR specified by ECX into EDX:EAX.
WRMSR:
Write the value in EDX:EAX to MSR specified by ECX.
MSR_CPUID0 EQU 00003000h
MSR_CPUID1 EQU 00003001h
mov ecx, MSR_CPUID0
RDMSR ; get values
mov edx, ‘cdeR’ ; write edx:eax to MSR in ecx. No change to eax.
WRMSR
mov ecx, MSR_CPUID1
RDMSR
mov edx, ‘duol’ ; No change to eax
WRMSR
; Done
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Model Specific Registers
12 AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide
GeodeLink™ Architecture 32430C
3.0GeodeLink™ Architecture
3
GeodeLink™ architecture connects the internal modules of the AMD Geode™ GX processor using the data channels provided by GeodeLink Interface Units (GLIUs). GeodeLink modules are connected to GLIU ports 1 – 7 as shown in Figure 3-
1. Port 0 is always the GLIU itself. GLIUs can be chained together and up to a maximum of six GLIUs can be connected
allowing for 32 modules.
GLMC
1
0
CPU Core
3
Not Used
AMD Geode™
GX Processor
Not Used
7
VP
7
Not Used
6
6
GLIU0
GLIU0
0
GLIU1
GLPCI
1
2
GLIU1
4
4
5
GP
Not Used
2
3
5
GIO
DC
GLCP
USBC1
6
GLCP
AMD Geode™
CS5535
Companion
Device
7
0
GLPCI
ACC
GLIU
1
5
DD
4
3
2
USBC2
ATA C
PCI Bus
Figure 3-1. GeodeLink™ Architecture Topology
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GeodeLink™ Architecture
3.1 GeodeLink™ MSR Addressing
The GX processor’s MSRs are addressed from the source module to the port of the target module. The topology of the GX
processor must be understood to derive the address. An MSR address is parsed into two fields, the port address (18 bits)
and the index (14 bits). The port address is further parsed into six 3-bit channel address fields. Each 3-bit field represents,
from the perspective of the source module, the GLIU channels that are used to get to the destination module, starting from
the closest GLIU to the source (left most 3-bit field), to the farthest GLIU (right most 3-bit field). When the GLIU gets the
cycle, it reads the three MSBs of the address register, shifts those three bits of the 18 MSBs of the address register off, and
passes the transaction to the port indicated by the next three bits.
MSR addresses that are outside the module address spaces are invalid; meaning RDMSR/WRMSR instructions attempting
to use the address within the CPU core will cause a General Protection Fault. Unimplemented MSR accesses not in peripheral modules go to the bit bucket.
3.1.1 Addressing Example
GX Processor GeodeLink Modules/Addresses
Source: CPU Core -> Destination: GeodeLink Control Processor (GLCP)
2.3.0.0.0.0 -> 4C00xxxxh
CS5535 Companion Device GeodeLink Module/Addresses
Source: CPU Core -> Destination: SB_GLCP
2.4.2.7.0.0 -> 5170xxxxh
GLPCI acts like another GLIU
3.2 Descriptors
Descriptors are used to route memory or I/O resources through GLIUs to a GX processor module. Memory and I/O
addresses that do not have descriptors are subtractively decoded through the GLIUs and out to the PCI. It is important that
no descriptors overlap each other. The result is indeterminate.
3.2.1 Memory Descriptor Types
• Range - Covers a memory range in 4 KB granularity.
• Range Offset - Covers a memory range in 4 KB granularity with the destination address translated by an offset.
• Base Mask - Covers a memory range that is a power of 2 in size.
• Base Mask Offset - Covers a memory range that is a power of 2 in size with the destination address translated by an
offset.
• Swiss Cheese - Covers a 256 KB region split into 16 KB pieces to a module or the subtractive port.
3.2.2 I/O Descriptor Types
• Base Mask - Covers an I/O range that is a power of 2 in size.
• Swiss Cheese - Covers an 8-byte region split into 1-byte pieces to a module or the subtractive port.
14 AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide
Initialization 32430C
4.0Initialization
4
4.1 Processor Initialization
The AMD Geode™ GX processor contains many of the components normally found in system support chipsets.
GeodeROM must set up these components, including the DRAM controller, L1 cache controller, clock control, and PCI controller as well as some proprietary systems like GeodeLink™ architecture.
This chapter contains descriptions and some pseudo code for GX processor-specific code sequences in GeodeROM. The
modifications are grouped into CPU core initialization, DRAM controller initialization, GeodeLink interface initialization, PCI
bus initialization, and miscellaneous other initializations/changes.
4.1.1 Set Clocks and Reset
Register: GLCP_SYS_RSTPLL (GX GLCP MSR Address 4C000014h)
The GX processor has separate clocks for the CPU core and GeodeLink interface. These clocks are derived from the system PLL, which is driven by the PCI clock. At power-on, these clocks default to a safe value. Setting the clock registers and
doing a reset will re-clock the GX processor.
The clocks are controlled by three divisors as shown in Figure 4-1. The Feed-back Divisor (FbDIV) in the PLL sets
sppl_raw_clk. Sppl_raw_clk is divided by the GeodeLink Divisor (MDIV) and the CPU Divisor (VDIV) to derive GeodeLink
clock and CPU clock. Sppl_raw_clk must be between 300 MHz and 800 MHz. The GeodeLink clock is used to clock the
memory. Therefore, the GeodeLink clock should never be greater than the speed and type of the system memory.
All the divisor bits, software bits, memory type bit, and reset bits are located in the GLCP_SYS_RSTPLL register. Once the
divisors and memory type (DDR/SDR) are set, the BIOS sets a reset flag and resets the CPU to continue initialization at the
desired CPU speed.
GeodeROM sets the clocks based on jumper settings that are interpreted to match SKUs defined for that version of the
CPU. SKUs are defined by PCI speed, memory type (SDR or DDR), and the jumper setting. GeodeROM can also use
FbDIV, MDIV, and VDIV values set by the user in CMOS for debugging.
If there is an incorrect setting in CMOS setup and the system cannot boot three times in a row, GeodeROM resets CMOS
to the defaults.
See Figure 7-4 on page 33 for example reset and system clock logic.
GLIU Clock
CPU Core Clock
SYSREF
(PCI Clock)
0 - 66 MHz
Clock
System PLL
300 - 800 MHz
Clock
FbDIV
MDIV
spll_raw-clk
VDIV
Figure 4-1. Clock Control
AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide 15
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Initialization
4.1.2 Calculating Processor Speed
Entry Conditions:
Stack and No-Stack versions required.
8254 timer available (port 61).
Procedure:
• Utilize the Real Time Stamp Counter (RTSC).
• Disable the L1 cache.
• Set up a channel of the 8254 Timer chip to count for a predetermined amount of time.
• Read the CPU RTSC and save the initial count value.
• Poll counter and wait for it to roll over.
• Read the CPU RTSC and save as the final count.
• Subtract the initial value of the RTSC from the final value.
• EDX:EAX now contains the number of clock ticks in the predetermined amount of time.
To get the value in MHz, divide the number of clocks by the time represented in microseconds (i.e., 5 ms = 5000).
4.1.2.1 CPU Identification
The CPUID check should be done as soon as possible. Use the CPUID instruction.
Check the Major and Minor Revision fields located in the GLCP_CHIP_REVID register (MSR Address 4C000017h[7:0]) for
the silicon revision.
4.1.3 Memory Controller Initialization
Registers:
MC_CF07_DATA (MSR Address 2000018h)
MC_CF8F_DATA (MSR Address 2000019h)
MC_CFCLK_DBUG (MSR Address 200001Dh)
The memory controller in the GX processor supports SDRAM and DDR memory. The memory controller and the RAM are
programmed via settings read from the SPD. The SPD is required for detection of PC66, PC100, PC133 and DDR RAM.
In the case of a closed system, where the RAM is soldered to the motherboard and there is no SPD, memory settings can
be stored in CMOS for initialization.
The SDRAM clock is set up prior to reset by the clock initialization.
• Address, bank, registered/unbuffered, and other values read from the SPD.
• Size memory in DIMM socket(s).
• Program Memory Controller.
• Set default refresh to an appropriate value.
16 AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide
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4.1.3.1 Size Memory
Entry Conditions:
4 GB descriptor in FS Core register.
Procedure:
For each DIMM:
• Set the following in the MC_CF07_DATA register MSR Address 20000018h):
— Module Banks per DIMM
– SPD byte 5: Number of DIMM Banks
— Banks per SDRAM device
– SPD byte 17: Number of Banks on SDRAM device
— DIMM size - Size = Density * Banks
– SPD byte 5: Number of DIMM Banks
– SPD byte 31: Module Bank Density
— Page size - Page size = 2^# Column Addresses
– SPD byte 4: Number of Column Addresses
• Set CAS Latency in MC_CF8F_DATA register (MSR Address 20000019h):
— SPD byte 18: CAS Latency
— Turn on the memory interface in MC_CFCLK_DBUG bit MASK_CKE[1:0] (MSR Address 2000001Dh[9:8]).
— Do 12 refreshes (CF07_PROG_DRAM) for the Memory Controller to synchronize.
— Set the refresh rate of the DIMM – SPD byte 12: Refresh Rate/Type.
— Load RDSYNC counter with sync value.
Note: See the AMD Geode™ GX Processors Data Book (publication ID 31505) for bit descriptions and allocation.
4.1.4 Test Extended DRAM
Entry Conditions:
4 GB descriptor in FS Core register.
All memory configured.
Procedure:
• Set GLIU descriptor to allow writes to memory.
• Make sure interface is turned on in MC_CFCLK_DBUG bit MASK_CKE[1:0] (MSR Address 2000001Dh[9:8]).
• Determine total amount of memory by doing a read/write test.
• For each 1 MB block of memory:
1) Walk a 1 through data bus at first location of block.
2) Walk a 0 through data bus at first location of block.
3) Check for stuck address line in the block.
• Continue test if no memory present for debug purposes.
4.1.5 GeodeLink™ Modules Initialization
Descriptors routing memory and I/O for GX processor modules are initialized by GeodeROM and Virtual System Architecture™ (VSA) technology. GeodeLink modules that are virtualized by VSA technology and use PCI memory or PCI I/O,
report that resource in the virtual PCI header. The GLIU is configured with MSRs like all GX processor modules.
AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide 17
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Initialization
4.1.5.1 GLIU Descriptors Initialization
Register:
P2D_BM, P2D_BMO, P2D_R, P2D_RO, P2D_SC (GLIU0 MSR Address 10000020h-1000003Fh, GLIU1 MSR
Address 40000020h-1000003Fh)
IO_BM, IO_SC (GLIU0 MSR Address 100000E0h-100000FFh, GLIU1 MSR Address 400000E0h-400000FFh)
Set up system memory map with GeodeLink Descriptors and Region Control Registers (RConfs). Descriptors and RConfs
must match each other. These register maps will look like the memory map from INT 15h AX = E820.
The responsibility of setting Descriptors and RConfs is split between GeodeROM and VSA technology. GeodeROM handles settings for system memory and VSA memory. Then the responsibility is handed off to VSA technology once it is
loaded to handle all other memory and I/O routing. This is most notable in the frame buffer initialization. See Memory Map,
Figure 7-2 on page 31 for a pictorial representation.
4.1.5.2 GLIU Priority Initialization
Each GeodeLink module has standard MSRs. GLD_MSR_CONFIG is one of the standard registers located at address
2001h in the GX processor and 0001h in the CS5535 companion device. Two fields in some of the GLD_MSR_CONFIG
registers can affect the module priority: Priority Level (PRI0) and Priority Domain (PID). These values default to zero. In the
case of data starvation or saturation on the GLIU, GeodeROM can adjust these values as recommended by AMD.
4.1.5.3 Cache Setup
The GX processor has a 16 KB instruction cache and a 16 KB data cache. The cache is enabled through register CR0 and
both caches can be disabled through MSRs regardless of the CR0 state.
4.1.5.4 Region Configuration
Region Configuration MSRs are used to describe the caching properties of each memory region. Unlike descriptors,
RConfs are designed to overlap. The Default Region Configuration Properties register (CPU Core MSR Address
00001808h) contains the base settings, and RConfs for the shadow area and other special regions supersede its setting.
Example Default Region Configuration Properties:
128 MB memory in the system 8 MB is used for frame buffer and 256 KB is used for VSA technology.
0x1808 = 0x25FFFC02 0x1077DF00
The Default Region Configuration Properties register, shown in Table 4-1, is the main register for GX processor cache settings.
Table 4-1. Default Region Configuration Properties Bit Descriptions
Bit Name (Note) Description
63:56 ROMRP ROM Region Properties. Region properties for addresses greater than ROMBASE (bits
[55:36]).
55:36 ROMBASE ROM Base Address. Base address for boot ROM. This field represents A[32:12] of the
memory address space, for 4 KB granularity.
35:28 DEVRP SYSTOP to ROMBASE Region Properties. Region properties for addresses less than
ROMBASE (bits 55:36]) and addresses greater than or equal to SYSTOP (bits [27:8]).
27:8 SYSTOP Top of System Memory. Top of system memory that is available for general processor
use. The frame buffer and other private memory areas are located above SYSTOP.
7:0 SYSRP System Memory Region Properties. Region properties for addresses less than SYS-
TOP (bits [27:8]). Note that Region Configuration 000A0000h-000FFFFFh takes precedence over SYSRP.
Note: Region Properties: 7:6 = Reserved; 5 = Write Serialize; 4 = Write Combine; 3 = Write-through; 2 = Write Protect;
1 = Write Allocate; 0 = Cache Disable.
18 AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide
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Registers:
CR0
RCONF MSRs: CPU Core MSR Address 00001808h-00001817h
Instruction Memory Configuration Register: CPU Core MSR Address 00001700h
Data Memory Configuration Register: CPU Core MSR Address 00001800h
Entry Conditions:
None
Procedure:
IF <L1 cache requested>
Setup the Default Region Configuration Properties and any other RCONFs required.
Write Cache Disable and Not Write-Through bits (bits [30:29]) in the CR0 register.
WBINVD
ENDIF
Note: See Figure 7-2 on page 31 for a pictorial presentation.
GLPCI Regions
The GLPCI has similar MSRs to the CPU Core Region Configuration registers for inbound transactions. These memory
regions control the memory hole from 6460 KB to 1 MB. Six flexible region MRSs are assigned: Memory Region 0 Configuration (R0) through Memory Region 5 Configuration (R5).
Descriptor Allocation
Register: PHY_CAP (MSR Address GLIU0: 10000086h, GLIU1: 40000086h)
Each GLIU descriptor allocation is defined in the PHY_CAP register.
Descriptor MSR Address GLIU0 GLIU1
P2D_BM 10000020h 00000000h-00007FFFh 00000000h-00007FFFh
10000021h 00080000h-0009FFFFh 00080000h-0009FFFFh
10000022h 4FFFC000h-4FFFFFFFh 4FFFC000h-4FFFFFFFh
10000023h 000A0000h-000BFFFFh 000A0000h-000BFFFFh
10000024h Not used by GeodeROM. Not used by GeodeROM.
10000025h Not used by GeodeROM. Not used by GeodeROM.
P2D_BMO 10000026h 40400000h-4043FFFFh 40400000h-4043FFFFh
10000027h Not used by GeodeROM. Not used by GeodeROM.
P2D_R 10000028h 00100000h-0E7BFFFFh 00100000h-0E7BFFFFh
P2D_RO 10000029h 50000000h-517FFFFFh 50000000h-517FFFFFh
1000002Ah 4FFF8000h-4FFFBFFFh 4FFF8000h-4FFFBFFFh
1000002Bh Not used by GeodeROM. Not used by GeodeROM.
P2D_SC 1000002Ch C000C7FFh, E000FFFFh C000C7FFh, E000FFFFh
AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide 19
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Initialization
4.2 AMD Geode™ CS5535 Companion Device Initialization
The Geode™ CS5535 is a complete companion device to the GX processor. The Geode CS5535 incorporates the
GeodeLink technology developed in the GX processor to make a transparent GeodeLink through the PCI to the CS5535
device. The CS5535 companion device contains many of the components normally found on the SuperI/O chip.
GeodeROM and VSA2 technology initialize these components, including the hard disk controller, USB controllers, GPIOs,
RTC, SMBus, Local bus, and other legacy components. This chapter contains descriptions as well as some pseudo code
for GX processor-specific code sequences in GeodeROM. The GX processor and CS5535 device do not implement complete PCI bus controllers, so GeodeLink modules that must be identified and configured by an operating system have their
PCI configuration spaces virtualized by VSA.
4.2.1 Chipset ID
Hardware PCI Header ID = 002A100Bh
Virtual PCI Header ID = 002B100bh
4.2.2 Set ID Select (IDSEL)
The CS5535 companion device number is changeable by a 32-bit, write once register located in I/O space 0. By default, the
CS5535 is located at device 15 (IDSEL = AD25). To insure that it is not accidentally moved, it must be programmed very
early in post. The External MSR Access Configuration Register (GX GLPCI MSR Address 50000201Eh) must match the
device number to route MSR transactions across the PCI bus.
Example:
; set IDSEL
mov eax, 02000000h ; IDSEL = AD25, device #15
; mov eax, 04000000h ; IDSEL = AD30, device #20
out 0000h, eax
; set ExtMSR
mov eax, 0F0F0F0Fh ; device #15
mov edx, 000F0F0Fh ; device #15
; mov eax, 14141414h ; device #20
; mov edx, 00141414h ; device #20
mov ecx, extMSR
WRMSR
4.2.3 GLIU Initialization
The CS5535 companion device contains one GLIU that connects up to six peripheral modules. The GLIU routes memory
and I/O for the attached modules. Descriptors controlling memory and I/O for the attached modules are initialized by VSA
technology. GeodeLink modules can be scanned for their identification. Non-legacy GeodeLink modules that must be visible on the PCI bus will have PCI headers virtualized by VSA technology. The GLIU is configured with MSRs like all GX processor and CS5535 device modules.
VSA technology is also responsible for the Geode CS5535 descriptor allocation.
4.2.4 Diverse Device Initialization
The Diverse Device (DD) is a collection of new and legacy devices that are located in I/O space and connected by the Local
bus. It is also the subtractive decode port of the CS5535. Any memory or I/O not claimed by the DD is passed on to the Low
Pin Count (LPC) bus. The CS5535 has provided complete flexibility to put non-legacy Local bus devices at any I/O location
by implementing Local BARs (LBARs). The following subsections show recommended locations in I/O space to set the
LBARs. Devices that may be used before VSA is initialized will be set by GeodeROM.
20 AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide
Initialization
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4.2.4.1 IRQ Mapper
Location: I/O 20-21 master Programmable Interrupt Controller (PIC), I/O A0-A1 slave PIC, I/O 4D0 edge/level
PIC shadow register at MSR Address 51400034h
The use of the IRQ Mapper LBAR is optional since it is always accessible via MSRs. The LBAR is for
the Mask and Mapper (MM) and the extended PIC (XPIC).
Description:
The IRQ Mapper is a combination of a Mapper and Mask (MM), an XPIC, and two Legacy 8259 compatible PICs (LPIC).
Initialization: At reset, the PIC subsystem comes up in legacy mode. VSA initializes the XPIC to generate ASMI from
GPIOs. Devices on the XPIC are hard wired to Interrupt Groups (IG) in the MM and XPIC. The XPIC is
hooked to the LPIC on interrupts [0:1], [3:15]. The rest (16:64) are hooked to ASMI.
The XPIC has several incoming sources. They are IRQ, LPC, Y, and Z sources. The Y sources include software, USB, RTC
alarm, audio, power management, NAND Flash, SMB, KEL, and UARTs. The Z sources include eight MFGPTs and eight
GPIOs. During PCI scan, GeodeROM allocates memory, I/O, and interrupts to the PCI devices. This includes the virtual
devices emulated by VSA. VSA is responsible for the setup of the XPIC mapper for the devices it is virtualizing.
4.2.4.2 Keyboard Emulation Logic (KEL) 1+ 2
Location:
Description:
Initialization:
NA
Used for A20 support as well as USB keyboard emulation.
VSA technology.
4.2.4.3 System Management Bus (SMBus)
Location:
Description:
6000h
SMBus is an industry standard two-wire serial interface. The SMBus is essentially an ACCESS.bus and
is the interface used to read the DRAM SPD.
Initialization:
GeodeROM sets the LBAR with the desired location and the GPIOs for SMBus. The recommended
address (SMBADDR) is 0EFh.
4.2.4.4 GPIO and ICF
Location:
Description:
6100h
There are 23 GPIOs in Working mode and 5 in Standby mode. The GPIO registers are such that there is
no need to do read/modify/writes. GPIO registers associated with bit settings are 32 bits. Thus, 16 GPIO
may be changed at once. These are organized into Low and High banks. The Low bank deals with
GPIOs 0 through 15 while the High bank deals with GPIOs 16 through 31.
Be aware of specification update issue #113 in certain silicon revisions (as of this writing, see AMD
Geode™ CS5535 Companion Device Specification Update Silicon Revision A3 (publication ID 31534)).
After a suspend, writing the register can not be done atomically.
Initialization:
VSA technology will set and use GPIOs connected with SMIs.
Many GPIOs are muxed with other signals and must be set up appropriately. There is a GPIO INT and
Power Management Event (PME) Mapper that maps GPIOs to the PIC and power management subsystem.
4.2.4.5 Multi Function General Purpose Timers (MFGPTs)
Location:
Description:
6200h
Timers are used by VSA mostly. The timers can set and be set by GPIOs. The timers can output to nonmaskable interrupts and cause an ASMI through the XPIC with interrupts.
Initialization:
AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide 21
VSA technology.
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4.2.4.6 ACPI
Location:
Description:
Initialization:
9C00h or other normal ACPI location.
NA
ACPI VSM
4.2.4.7 Power Management Logic
Location:
Description:
Initialization:
9D00h put on the end of ACPI.
NA
VSA technology and ACPI VSM as needed.
4.2.4.8 Flash Interface
Location:
Description:
Initialization:
4 LBARs for 4 Flash devices
NA
The default values for the LBARs are located in BDCFG.INC in the platform directory, but can be
changed at Boot via setup. The Flash interface is configured in the code at ChipsetFlashSetup in
CHIPSET.ASM based on the corresponding NVRAM values.
Initialization
4.2.4.9 Other Legacy DD Initialization
Location:
Description:
Initialization:
Default legacy definitions.
Initialize COM ports, LPT ports, RTC.
These devices are initialized in the same fashion as with a normal SuperI/O and CS5535. Any MSR register settings will be done in chipset individualization. GeodeROM can handle multiple devices and locations by design.
22 AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide
Initialization
4.2.4.10 DD I/O Locations
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Table 4-2. Diverse Device I/O Locations
Location Device
0020h PIC Master Command and Status
0021h PIC Master Command and Status
0060h USB - Keyboard and Mouse Data
0064h USB - Keyboard and Mouse Command and Status (KEL)
0070h RTC Address
0071h RTC Data
00A0h PIC Slave Command and Status
00A1h PIC Slave Command and Status
02E8h UART/IR COM4
02F8h UART/IR COM2
03E8h UART/IR COM3
03F8h UART/IR COM1
04D0h PCI Level/Edge IRQ0-7
04D1h PCI Level/Edge IRQ8-15
6000h SMBus
6100h GPIO and ICF
6200h General Purpose Timers
6400h Flash BAR
6500h Flash BAR
6600h Flash BAR
6700h Flash BAR
9C00h ACPI - Subdivide to support GX processor and CS5535 companion device
9D00h Power Management Logic - Placed at the end of ACPI
4.2.5 ATA-5 / Hard Drive Initialization
Hard drive initialization is handled by a system ROM that is loaded by GeodeROM. The hard drive ROM contains the hard
drive initialization, the PIO modes support, and the interrupt support.
New to the hard drive ROM is the UDMA setup, so that default drivers may be used in some operating systems. The UDMA
setup includes detecting the 80-conductor IDE cable for UDMA/66 support.
4.2.6 Universal Serial Bus (USB)
There are two Universal Serial Bus Controllers (USBCs) each containing a GeodeLink™ Adapter, PCI Adapter, and USB
Core blocks. The GeodeLink Adapter (GLA) translates GeodeLink transactions to/from Local bus transactions. The GLA
interfaces to a 64-bit GLIU (GeodeLink Interface Unit) and a 32-bit Local bus. The GLA supports in-bound memory and I/O
requests, which are converted by the PCI Adapter (PA) into PCI memory and I/O requests that target the USBC. It also supports in-bound MSR transactions to the MSRs.
4.2.7 AC97 Audio Controller Initialization
The audio codec is initialized by the native audio driver. The virtual PCI header contains the IRQ line. The IRQ is set
through the regular PCI initialization and IRQ mapping.
AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide 23
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Initialization
4.2.8 GeodeLink™ Control Processor Initialization
The Geode CS5535 GLCP contains the diagnostic bus, the JTAG interface clock, south bridge control, and power management.
4.3 Virtual System Architecture™ Initialization
Virtual System Architecture (VSA) is the System Management Mode (SMM) software. VSA virtualizes PCI BARs and headers for GeodeLink modules as well as its normal functions described in the AMD Geode™ GeodeROM Functional Specifi-
cation (publication ID 32087).
4.3.1 Allocate Processor Frame Buffer and VSA2 Memory
The GX processor employs a Unified Memory Architecture (UMA), meaning the frame buffer is allocated from the total system memory. The GeodeROM code programs the amount of system memory initially needed for VSA memory. VSA can
adjust the descriptors once it is loaded. When internal video is enabled, VSA allocates the frame buffer and graphics
descriptors. The amount of memory currently allowed for frame buffer use ranges from 4 to 16 MB.
To inhibit operating system DRAM detection code from reporting the frame buffer as part of system memory, a GLIU offset
descriptor is set to send transactions to the PCI bus and program Region Configuration Registers to set the region noncacheable. This means that DOS, Windows®, OS/2, and UNIX are never aware of the graphics memory portion of system
memory. This mapping prevents unwanted access to the graphics frame buffer and other critical graphics information stored
in this area. The memory is claimed in the Virtual PCI header.
4.4 PCI Bus Initialization
The GX processor does not incorporate a standard PCI bus controller. The GX processor and CS5535 devices do not have
PCI headers. VSA emulates all the PCI headers and the GeodeLink is configured to route memory and I/O for those modules. This requires VSA to be initialized before PCI scan.
For Virtual PCI headers, VSA sets GeodeLink descriptors and the Region Control Registers as requested by the modules
during PCI scans.
PCI scan supports interrupt mapping and PCI Bridge support. There is no plan for ISA PnP support at this time.
The PCI controller configuration registers are accessed through PCI type one configuration access mechanism (using Ports
CF8h and CFCh).
24 AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide
Initialization
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4.5 Miscellaneous Initializations
In addition to the previous processor initializations, the graphics card(s) must also be initialized.
4.5.1 Initialize Graphics Subsystem
There are two different modes: CRT and TFT. Graphics initialization needs to identify which kind of support is required by
reading an MSR in the Video Processor.
Entry Conditions:
4 GB descriptor in FS core register.
GeodeLink descriptors initialized.
VSA initialized.
First MB of DRAM functional.
Interrupts enabled.
DMA initialized.
PCI bus functional.
Procedure:
IF <PCI graphics card exists> THEN
Jump to PCI graphics BIOS for initialization.
ELSEIF <ISA graphics card exists> THEN
Jump to ISA graphics BIOS for initialization.
ELSE <SoftVGA required by setup> THEN
Initialize SoftVGA during VSA initialization
Jump to integrated graphics BIOS for initialization
ENDIF
4.5.1.1 Monochrome Support
GeodeROM includes the appropriate INT 10h support for monochrome video adapters.
SoftVG needs an extra hole at B000h-B7FFh when a mono card is present.
4.5.1.2 Dual Monitor Support
GeodeROM provides dual monitor support. GeodeROM assumes that the external card is the primary graphics card and
that the XpressGRAPHICS™ system is secondary.
AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide 25
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Initialization
26 AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide
Implementation 32430C
5.0Implementation
5
5.1 Implementation
The following is a collection of implementation details to consider in the GeodeROM implementation phase.
5.1.1 Clocking
There are two clock inputs to the GX processor: the system PCI clock (SYSREF) used to derive the Core clock, and the
GeodeLink™ clock used for the memory clock. The Dot clock is used for video display control. The Core and GeodeLink
clocks can be programmed and restarted by reseting the GX processor.
5.1.2 Scratchpad Initialization
The scratchpad is no longer needed either for BLT buffers or by the audio code for variable storage. The scratchpad is not
supported in the GX processor CPU Core.
5.1.3 Post Codes
Post codes are sent out to port 80 throughout GeodeROM. A Post codes list is available in the AMD Geode™ GeodeROM
Functional Specification (publication ID 32087) to help users debug their problems.
AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide 27
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Implementation
28 AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide
Setup Options 32430C
6.0Setup Options
6
Initial configuration is set in the configurator at build time. Based on those settings, there are some setup options at runtime
that are platform specific. Check your platform specification for more details.
Desired Setup Options:
• Clock configuration - complete control of system PLLs
— Default: Use strap setting for core. GeodeLink™ interface frequency is calculated based on DIMM type.
• PM settings
— Default: Off
• Audio enable/disable
— Default: Enabled
• Video Primary/Secondary/Disabled
— Default: Secondary
• Video Memory Size
— Default: 24 MB
• Cache enable/disable
— Default: Write Back
• MTest enable/disable
— Default: disabled
• LPT enable/disable
— Default: 378
Note: If a setting is incorrect and the system cannot boot three times, CMOS is reset to the default setup options.
AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide 29
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30 AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide
Memory Map 32430C
7.0Memory Map
7
Figures 7-1, 7-2, and 7-3 show the system memory. Figure 7-1 is the GLIU Descriptor Map, Figure 7-2 shows the Core
Cache descriptors, and Figure 7-3 on page 32 shows the Core cache region configurations.
Figure 7-4 on page 33 shows the flow of GeodeROM in the GX processor/CS5535 system.
Memory Descriptors
Frame Buffer Offset
Video Descriptors
(RO, VP + GP + DC)
VSA Offset
Frame Buffer Descriptors
(RO, GLMC)
SMM Descriptor (RO, GLMC)
SysTop Descriptor (R, GLMC)
Two Shadow Descriptor (SC, GLMC)
A0000h - DFFFFh, E0000h-11FFFh
Two Conv Desc (BM, MC)
0-7FFFFh, 80000h-9FFFFh
BM - Base Mask
R - Range
SC - Swiss Cheese
Figure 7-1. GLIU Descriptor Map
Memory Mapped Frame Buffer
Memory Mapped Video Registers
Memory Mapped VSA
System and Option ROMs
Conventional Memory
BMO - Base Mask Offset
RO - Range Offset
No Swiss Cheese Offset
ROM
Subtractive to PCI
Subtractive to PCI
Subtractive to PCI
Subtractive to PCI
Subtractive to PCI
Frame Buffer
VSA
Subtractive to PCI
Extended Memory
FFFFFFFFh (4 GB)
FFFC0000h
50000000h
40400000h
subtracted from
Extended Memory
Top of DRAM
VSA and Video Memory
Top of System
(OS) RAM
A0000h - 100000h (640 KB - 1 MB)
Figure 7-2. CPU Core Cache Descriptors
AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide 31
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Memory Map
RCONF_DEFAULT ROMRC
RCONF_DEFAULT ROMBASE
RCONF_DEFAULT DEVRG
RCONF_SMM
RCONF_DEFAULT SYSTOP
RCONF_DEFAULT SYSRC
RCONF_A0_BF-RCONF_E0_FF
ROM
PCI
Memory Mapped
PCI
PCI
PCI
Memory Mapped Frame Buffer
Memory Mapped Video Registers
Memory Mapped VSA
PCI
Frame Buffer
VSA
PCI
Extended Memory
FFFC0000h
50000000h
40400000h
subtracted from
Extended Memory
Top of DRAM
VSA and Frame Buffer
Top of System
(OS) RAM
RCONF_DEFAULT SYSRC
RCONF_BYPASS
RCONF-RCONF7
Figure 7-3. CPU Core Cache Region Configurations
System and Option ROMs
Conventional Memory
SMM and DMM header and
table walk properties
Not Used
32 AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide
Memory Map
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Reset
ROM
Fetch
Uses CPU ID instruction.
Load CMOS/
NVRAM Defaults
N
Y
CPU ID
Correct?
Y
CMOS/NVRAM
Valid and
Checksum
Ok?
Y
Failed to
Boot
3 Times?
N
Early CS5535
Initialization
PLL Flag
indicates
2nd Pass?
N
Halt
Failed boots need a POR
reset and will always take this path.
Y
Jumper settings correspond
to a table of SKUs for each
revision of the CPU.
PLL settings can be set
manually for debug.
N
Get Core and GLIU
Settings from Jumper
Settings or CMOS
CPU Speed to get
PCI Clock
DRAM Clock Setting
from SPD
Set All Clocks
GLCP_SYS_RSTPPL
(MSR Addr. 4C00014h)
Set PLL Flag
Internal PLL Reset
Continue POST
PLL Reset completed
Figure 7-4. GeodeROM Flow - GX Processor/CS5535 Device
AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide 33
Finish Post
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Memory Map
CS5535 descriptor
set here,
after shadow.
Setup Stack
Shadow ROM
Initialize and
Enable Cache
Northbridge
Initialization and
CPU Bug Fixes
Chipset
Initialization
Enable
Interrupts
VSA
Initialization
System ROM
Initialization
PCI and Video
Option ROM
Initialization
Keyboard
F1 Pressed?
N
Flag
Reset Reboot
Y
SuperI/O
Initialization
Setup
Flag
Reset Reboot
Reset
INT 19
Figure 7-4 "GeodeROM Flow - GX Processor/CS5535 Device" (Continued)
34 AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide
Appendix A: Support Documentation 32430C
Appendix ASupport Documentation
A
A.1 Document Revision History
This section reports the revision/creation process of the porting guide. Any revisions (i.e., additions, deletions, parameter
corrections, etc.) are recorded in the table(s) below.
Table A-1. Revision History
Revision #
(PDF Date) Revisions / Comments
A (30-Jun-2005) Initial release.
B (22-Mar-2006) The goal was to remove “Confidential” to make this an non-NDA document. Also incorporated other
minor corrections. See revision B for details.
C (25-Apr-2006) • Section 4.0 "Initialization" on page 15: Several sub-sections had incorrect MSR Addresses. Most
were 7 digits long instead of 8 (missing a 0). Corrected these.
• Section 4.2.4.8 "Flash Interface" on page 22: Changed 5535.ASM to CHIPSET.ASM.
AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide 35
www.amd.com
One AMD Place • P.O. Box 3453 • Sunnyvale, CA 94088-3453 USA • Tel: 408-749-4000 or 800-538-8450 • TWX: 910-339-9280 • TELEX: 34-6306
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