Broadcom PLX PCI 9052RDK-LITE, Справочник по аппаратуре

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4. ISA to PCI Migration
This chapter explains how to use the PCI 9052RDK-LITE to migrate ISA bus designs to PCI bus designs.
4.1 ISA Register Configuration
The PCI 9052 uses a re-mapping process to map an ISA card into PCI space. Local address spaces 0
and 1 are used for memory accesses and I/O space accesses, respectively. During boot up, the PC BIOS
reads the amount of memory or I/O space requested by the PCI 9052 and allocates this within the PCI
memory map. The base addresses of the various regions are written back into the PCIBAR registers.
4.1.1 Range Register
The Range Registers LAS0RR and LAS1RR are used to store memory range and I/O space range,
respectively. In order to allocate the correct amount of memory in PCI, the two’s complement of the
amount of ISA memory and/or ISA I/O space required is stored into the appropriate LASxRR registers.
The range for a local address space must be a power of 2. In addition, the least significant bit of the
LAS1RR register must be set to 1 to ensure it is mapped into the I/O space.
4.1.2 Base Address Re-map Register
The Base Address Re-map Registers LAS0BA and LAS1BA are used to store ISA card memory and I/O
base addresses, respectively.
To enable a local address space, and allow it to be mapped into PCI space, LASxBA register bit-0 should
be set to “1”. If only I/O space is required, then it is not necessary to enable LAS0BA register bit-0.
The base address programmed into the LASxBA register must be a multiple of the appropriate range or 0.
This restriction may require lowering the base address and increasing the range to ensure that both the
ISA base address and range are covered.
4.1.3 Chip Select Register
The Chip Select Registers CS0BASE and CS1BASE should be configured to map directly over Local
Address Spaces 0 and 1, respectively.
There are several descriptions in the PCI 9052 data book and on the PLX web site (www.plxtech.com)
explaining how to program the CSxBASE registers. For occasional use the simplest method is to write the
powers of 2 down on a sheet of paper, placing 1's in the appropriate places and then converting this to a
hex number. For example, if you wanted a chip select with a range of 16 bytes and a base address of
0x100h, then you would do the following:
1. Place a 1 in bit 0 (to enable the chip select).
2. Place a 1 in the column immediately to the right of the range required. In this example, the
required range is 16; therefore a 1 is placed in the 8 column.
3. Set the appropriate bits for the base address to the left of the range bit. In this example, the
desired base address is 0x100h, therefore a 1 is placed in the 256 column. The completed table
should look like this:
2048 1024 512 256 128 64 32 16 8 4 2 1
0 0 0 1 0 0 0 0 1 0 0 1
4. Convert the binary value to hex. In this example the CSxBASE register would be loaded with
0x00000109h
Using this method will always force the base address to be a multiple of the range.
PCI 9052RDK-LITE Hardware Reference Manual v1.3
© 2004 PLX Technology, Inc. All rights reserved . 15