
Chapter 6: Register Descriptions 6–11
PCI Express Avalon-MM Bridge Control Register Content
August 2014 Altera Corporation IP Compiler for PCI Express User Guide
The interrupt status register (Table 6–19) records the status of all conditions that can
cause an Avalon-MM interrupt to be asserted.
An Avalon-MM interrupt can be asserted for any of the conditions noted in the
Avalon-MM interrupt status register by setting the corresponding bits in the interrupt
enable register (Table 6–20).
PCI Express interrupts can also be enabled for all of the error conditions described.
However, it is likely that only one of the Avalon-MM or PCI Express interrupts can be
enabled for any given bit. There is typically a single process in either the PCI Express
or Avalon-MM domain that is responsible for handling the condition reported by the
interrupt.
Avalon-MM Mailbox Registers
A processor local to the system interconnect fabric typically requires write access to a
set of Avalon-MM-to-PCI Express mailbox registers and read-only access to a set of
PCI Express-to-Avalon-MM mailbox registers. Eight mailbox registers are available.
The Avalon-MM-to-PCI Express mailbox registers are writable at the addresses shown
in Table 6–21. When the Avalon-MM processor writes to one of these registers the
corresponding bit in the PCI Express interrupt status register is set to 1.
Table 6–19. PCI Express to Avalon-MM Interrupt Status Register Address: 0x3060
Bits Name Access Description
[15:0] Reserved — —
[16] P2A_MAILBOX_INT0 RW1C 1 when the P2A_MAILBOX0 is written
[17] P2A_MAILBOX_INT1 RW1C 1 when the P2A_MAILBOX1 is written
[18] P2A_MAILBOX_INT2 RW1C 1 when the P2A_MAILBOX2 is written
[19] P2A_MAILBOX_INT3 RW1C 1 when the P2A_MAILBOX3 is written
[20] P2A_MAILBOX_INT4 RW1C 1 when the P2A_MAILBOX4 is written
[21] P2A_MAILBOX_INT5 RW1C 1 when the P2A_MAILBOX5 is written
[22] P2A_MAILBOX_INT6 RW1C 1 when the P2A_MAILBOX6 is written
[23] P2A_MAILBOX_INT7 RW1C 1 when the P2A_MAILBOX7 is written
[31:24] Reserved — —
Table 6–20. PCI Express to Avalon-MM Interrupt Enable Register Address: 0x3070
Bits Name Access Description
[15:0] Reserved — —
[23:16]
P2A_MB_IRQ
RW
Enables assertion of Avalon-MM interrupt
CraIrq_o
signal when
the specified mailbox is written by the root complex.
[31:24] Reserved — —
Table 6–21. Avalon-MM-to-PCI Express Mailbox Registers, Read/Write (Part 1 of 2) Address Range: 0x3A00-0x3A1F
Address Name Access Description
0x3A00 A2P_MAILBOX0 RW Avalon-MM-to-PCI Express mailbox 0
0x3A04 A2P _MAILBOX1 RW Avalon-MM-to-PCI Express mailbox 1
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