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Intel
®
IXP42X product line and IXC1100 control plane processors—PCI Controller
Intel
®
IXP42X Product Line of Network Processors and IXC1100 Control Plane Processor
DM September 2006
268 Order Number: 252480-006US
6.14.2.16 PCI Doorbell Register
(PCI_PCIDOORBELL)
6.14.2.17 AHB to PCI DMA AHB Address Register 0
(PCI_ATPDMA0_AHBADDR)
Register PCI_AHBDOORBELL
Bits Name Description
Reset
Value
PCI Access AHB Access
31:0 ADB
PCI generated doorbell interrupt to an AHB agent.
Normally read/write-1-to-set from PCI and read/
write-1-to-clear from AHB. Read/write from the AHB
side if Doorbell Test mode is enabled by setting
pci_csr.DBT to a 1.
0x00000000 RW1S
RW1C (RW if
pci_csr.DBT
=1)
Register Name: PCI_PCIDOORBELL
Hex Offset Address: 0xC000003C Reset Hex Value: 0x00000000
Register
Description:
The Intel XScale processor writes this register to generate an interrupt to an external PCI device on
PCI_INTA_N (INTA# on PCI). Any bit set to a 1 will generate the PCI interrupt if the PCI doorbell interrupt
is enabled (pci_inten.PDBEN = 1). This register is write-1-to-set from AHB and write-1-to-clear from PCI.
The Intel XScale processor writes a 1 to a bit or pattern of bits to generate the interrupt. The external
PCI device reads the register and writes 1(s) to clear the bit(s) and de-assert the interrupt. If the DBT
(Doorbell Test) bit is set in the pci_csr register, all bits become read/write from the AHB bus.
Access: See below.
31 0
PDB
Register
PCI_PCIDOORBELL
Bits Name Description
Reset
Value
PCI Access AHB Access
31:0 PDB
AHB generated doorbell interrupt to PCI. Normally
read/write-1-to-set from AHB and read/write-1-to-
clear from PCI. Read/write from the AHB side if
Doorbell Test mode is enabled by setting pci_csr.DBT
to a 1.
0x00000000 RW1C
RW1S (RW if
pci_csr.DBT
=1)
Register Name: PCI_ATPDMA0_AHBADDR
Hex Offset Address: 0xC0000040 Reset Hex Value: 0x00000000
Register
Description:
Source address on the AHB bus for AHB to PCI DMA transfers. Paired with pci_atpdma1_ahbaddr to allow
buffering of DMA transfer requests.
Access: See below.
31 210
address 0 0
Register
PCI_ATPDMA0_AHBADDR
Bits Name Description
Reset
Value
PCI Access AHB Access
31:2 address AHB word address 0x00000000 RO RW
1:0 Lower AHB address bits hard-wired to zero. 00 RO RO