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AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide 17
Initialization
32430C
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 Architec-
ture™ (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.