PI7C8152B datasheet(28/90 Pages) PERICOM

28 / 90 page

PI7C8152A & PI7C8152B

2-PORT PCI-TO-PCI BRIDGE

ADVANCE INFORMATION

Page 28 of 90

October 16, 2003 – Revision 1.11

PI7C8152x performs a Type 1 to Type 0 translation when the Type 1 transaction

is generated on the primary bus and is intended for a device attached directly to the

secondary bus. PI7C8152x must convert the configuration command to a Type 0 format so

that the secondary bus device can respond to it. Type 1 to Type 0 translations are

performed only in the downstream direction; that is, PI7C8152x generates a Type 0

transaction only on the secondary bus, and never on the primary bus.

PI7C8152x responds to a Type 1 configuration transaction and translates it into a Type 0

transaction on the secondary when the following conditions are met during the address

phase:

The lowest two address bits on P_AD[1:0] are 01b.

The bus number in address field P_AD[23:16] is equal to the value in the secondary

bus number register in configuration space.

The bus command on P_CBE[3:0] is a configuration read write transaction.

When PI7C8152x translates the Type 1 transaction to a Type 0 transaction on

the secondary interface, it performs the following translations to the address:

Sets the lowest two address bits on S_AD[1:0] to 0.

Decodes the device number and drives the bit pattern specified in Table 3-6 on

S_AD[31:16] for the purpose of asserting the device’s IDSEL signal.

Sets S_AD[15:11] to 0.

Leaves unchanged the function number and register number fields.

PI7C8152x asserts a unique address line based on the device number. These address lines

may be used as secondary bus IDSEL signals. The mapping of the address lines depends on

the device number in the Type 1 address bits P_AD[15:11]. Table 3-6 presents the mapping

that PI7C8152x uses.

Table 3-6 DEVICE NUMBER TO IDSEL S_AD PIN MAPPING

Device Number

P_AD[15:11]

Secondary IDSEL S_AD[31:16]

S_AD

00000

0000 0000 0000 0001

00001

0000 0000 0000 0010

00010

0000 0000 0000 0100

00011

0000 0000 0000 1000

00100

0000 0000 0001 0000

00101

0000 0000 0010 0000

00110

0000 0000 0100 0000

00111

0000 0000 1000 0000

01000

0000 0001 0000 0000

01001

0000 0010 0000 0000

01010

0000 0100 0000 0000

01011

0000 1000 0000 0000

01100

0001 0000 0000 0000

01101

0010 0000 0000 0000

01110

0100 0000 0000 0000

01111

1000 0000 0000 0000

10h – 1Eh

10000 – 11110

0000 0000 0000 0000

1Fh

11111

Generate special cycle (P_AD[7:2] = 00h)

0000 0000 0000 0000 (P_AD[7:2] = 00h)

PI7C8152B Datasheet(PDF) 28 Page - Pericom Semiconductor Corporation

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