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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
August 2006
Develepor’s Manual
Order Number: 306262-004US
547
PCI Controller—Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
10.3.5
PCI Controller Interrupts
The PCI Controller supports generation of PCI interrupts and interrupts to internal AHB
agents. Complete control of the interrupt sources and enabling is provided using two
registers: the PCI Interrupt Status Register (PCI_ISR) and PCI Interrupt Enable
Register (PCI_INTEN).
10.3.5.1
PCI Interrupt Generation
The PCI Door Bell Register (PCI_PCIDOORBELL) is used to generate a PCI interrupt on
the PCI Bus using the PCI_INTA_N signal. This register is read/write-1-to-set from the
AHB bus, and read/write-1-to-clear from the PCI bus. All bits are ORed together to
generate the PCI interrupt. The sequence is:
• An AHB agent writes a pattern of ones to the PCI_PCIDOORBELL register, setting
the corresponding bits in the register.
• The interrupted PCI device reads the bit pattern in the doorbell register and writes
the same pattern back to clear the bits and deassert the interrupt.
Figure 100. Byte Lane Routing During CSR Accesses
B4304-01
31
24
PCI CSR Read
CSR
Register
3
2
1
0
23
16 15
8
7
0
31
24 23
16 15
8
7
0
31
24
3
2
1
0
23
16 15
8
7
0
31
24 23
16 15
8
7
0
CSR
Register
PCI Data
PCI Data
PCI CSR Write
31
24
AHB CSR Read
AHB Data
23
16 15
8
7
0
31
24 23
16 15
8
7
0
31
24 23
16 15
8
7
0
31
24 23
16 15
8
7
0
AHB Data
CSR
Register
CSR
Register
AHB CSR Write