Intel CM8062101038606, E5-4600, E5-2600, E5-1600 manual RdPCIConfig, PCI Configuration Address

2.5.2.8RdPCIConfig()

The RdPCIConfig() command provides sideband read access to the PCI configuration space maintained in downstream devices external to the processor. PECI originators may conduct a device/function/register enumeration sweep of this space by issuing reads in the same manner that the BIOS would. A response of all 1’s may indicate that the device/function/register is unimplemented even with a ‘passing’ completion code. Alternatively, reads to unimplemented registers may return a completion code of 0x90 indicating an invalid request. Responses will follow normal PCI protocol.

PCI configuration addresses are constructed as shown in Figure 2-44. Under normal in- band procedures, the Bus number would be used to direct a read or write to the proper device. Actual PCI bus numbers for all PCI devices including the PCH are programmable by BIOS. The bus number for PCH devices may be obtained by reading the CPUBUSNO CSR. Refer to the Intel® Xeon® Processor E5 Product Family Datasheet Volume Two document for details on this register.

Figure 2-44. PCI Configuration Address

31 28 27 20 19 15 14 12 11 0

Reserved

Bus

Device

Function

Register

PCI configuration reads may be issued in byte, word or dword granularities.

2.5.2.8.1Command Format

The RdPCIConfig() format is as follows: Write Length: 0x06

Read Length: 0x05 (dword)

Command: 0x61

Description: Returns the data maintained in the PCI configuration space at the requested PCI configuration address. The Read Length dictates the desired data return size. This command supports only dword responses with a completion code on the processor PECI clients. All command responses are prepended with a completion code that includes additional pass/fail status information. Refer to Section 2.5.5.2 for details regarding completion codes.

Figure 2-45. RdPCIConfig()

Note: The 4-byte PCI configuration address and read data field defined in Figure 2-45are sent in standard PECI ordering with LSB first and MSB last.

64	Intel® Xeon® Processor E5-1600/E5-2600/E5-4600 Product Families
	Datasheet Volume One