Rx-URME-031 Rev -
- DRAFT -
PMC551 Hardware Reference and Installation Manual
Page 9
5.1.2
BAR0
BAR0 is used to determine the size of the memory actually on the PMC551 in the system, and to
assign the base PCI address of the region that the PMC551 will occupy.
Memory sizing follows the PCI specification:
•
Write all 1’s to the register
•
Read back
On the reading a mask is returned in which all address bits that are NOT decoded by the PMC551
are returned as set. (Example: on a PMC551 configured for 32Mbyte the return value will be:
0xFE000000).
Once the memory size is determined the base address value is set.
Note: On most systems, this function is automatically performed by the BIOS or other power on
initialization. Care must be exercised when modifying this register. Prior to altering the value,
ensure that the Memory Enable (bit 1 in the CMD/STS register) is zero.
5.2
Waking up Memory
After power up, prior to accessing the memory on the PMC551, a “wakeup” procedure must be
executed. The following code fragment documents the necessary interactions. The procedures
prefixed with “pci_” should be implemented or replaced as appropriate for the local software
environment.
27..29
Reserved
30
System Error. Set to 1 in response to system error detected by PMC551. Write 1 to clear
31
Parity Error. Set to 1 in response to parity error. Write 1 to clear
Bit(s)
Function
0
0 - Indicates memory space address
1..2
Address range type. Not used by PMC551
3
Prefetch Enable. Set to enable prefetch. Should be set for best performance.
4..19
Reserved
20..31
Base Address