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20 AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide
Initialization
32430C
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 com-
plete 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 visi-
ble on the PCI bus will have PCI headers virtualized by VSA technology. The GLIU is configured with MSRs like all GX pro-
cessor 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.