CS5920 datasheet(111/160 Pages) AMCC

111 / 160 page

S5920 – PCI Product

Revision 1.01 – November 28, 2005

AMCC Confidential and Proprietary

DS1596

111

Data Book

Servicing a PCI Mailbox Interrupt (INTA# asserted):

1. Identify the interrupt source(s). Multiple interrupt sources are available on the S5920. The interrupt service

routine must verify that a mailbox generated the interrupt (and not some other interrupt source).

2. Check mailbox status. The mailbox status bits indicate which mailbox bytes must be read or written.

3. Access the mailbox. Based on the contents of MBEF, mailboxes are read or written. Reading an incoming

mailbox byte clears the corresponding status bit in MBEF.

4. Clear the interrupt source. The PCI INTA# signal is deasserted by clearing the interrupt request. The request

is cleared by writing a 1 to the appropriate bit.

Servicing the Add-On mailbox interrupt (IRQ# asserted):

1. Identify the interrupt source(s). Multiple interrupt sources are available on the S5920. The interrupt service

routine must verify that a mailbox generated the interrupt (and not some other interrupt source).

2. Check mailbox status. The mailbox status bits indicate which mailbox bytes must be read or written.

3. Access the mailbox. Based on the contents of AMBEF, mailboxes are read or written. Reading the incoming

mailbox byte clears the corresponding status bit in AMBEF.

INTCSR

Bit 23

PCI interrupt asserted

INTCSR

Bit 17

PCI incoming mailbox interrupt indicator

INTCSR

Bit 16

PCI outgoing mailbox interrupt indicator

MBEF

Bits 31:28

Full PCI incoming mailbox bytes

MBEF

Bits 15:12

Empty PCI outgoing mailbox bytes

OMB

Bits 31:0

PCI outgoing mailboxes

IMB

Bits 31:0

PCI incoming mailboxes

INTCSR

Bit 17

Clear PCI incoming mailbox interrupt

INTCSR

Bit 16

Clear PCI outgoing mailbox interrupt

AINT

Bit 23

Add-On interrupt asserted

AINT

Bit 17

Add-On outgoing mailbox interrupt indicator

AINT

Bit 16

Add-On incoming mailbox interrupt indicator

AMBEF

Bits 31:28

Empty Add-On outgoing mailbox bytes

AMBEF

Bits 15:12

Full Add-On incoming mailbox bytes

AIMB

Bits 31:0

Add-On incoming mailbox

AOMB

Bits 31:0

Add-On outgoing mailbox

CS5920 Datasheet(PDF) 111 Page - Applied Micro Circuits Corporation

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