Hello,
I am writing code for my platform's PCI Express controller.
I am stuck at the legacy PCI interrupt handling.
Interrupt requests are routed like this:
Cortex A9 MP <-- GIC(v1?) <-- system_intc <-- PCIe_root_complex
The PCIe root complex drives two interrupt signals to the system_intc
1) system_intc 54 = non-MSI interrupts
2) system_intc 55 = MSI interrupts
I think the MSI handling mostly works (although it's 340 lines long,
which seems excessive for such a common task; maybe the maintainers
will spot lots of redundant code when I submit).
As for non-MSI interrupts, there are 8 possible sources:
system_error
dma_read_ready
dma_write_ready
unsupported completion request
configuration request retry status
completer abort event
completion timeout event
legacy interrupt asserted (any of the 4 legacy interrupts)
Basically, I need to deal with the first 7 interrupts "internally"
in my PCIe root complex driver. But the last interrupt, I need to
"forward" it to the proper ISR (e.g. XHCI ISR).
For the "internal" handling, I think I need to register my own ISR
with the IRQF_SHARED flag. Then other drivers will be able to
register their ISR on the same interrupt line.
But how do I tell the PCI core that it's supposed to use interrupt 54
for legacy interrupts?
Here is my current DT:
msi0: msi@2e080 {
compatible = "sigma,msi";
reg = <0x2e04c 0x40>;
interrupt-parent = <&irq0>;
interrupts = <55 IRQ_TYPE_LEVEL_HIGH>;
msi-controller;
num-vectors = <32>;
};
pcie@30000000 {
compatible = "sigma,smp8759-pcie";
reg = <0x30000000 SZ_4M>, <0x2e02c 4>;
device_type = "pci";
bus-range = <0 3>;
#size-cells = <2>;
#address-cells = <3>;
#interrupt-cells = <1>;
ranges = <0x02000000 0x0 0x00400000 0x30400000 0x0
SZ_60M>;
msi-parent = <&msi0>;
interrupt-parent = <&irq0>;
interrupts = <54 IRQ_TYPE_LEVEL_HIGH>;
};
I traced the action into pdev_fixup_irq()
which calls of_irq_parse_and_map_pci()
How do I tell Linux that
- All the legacy PCI interrupts are muxed to a single line
- And this line is routed to system interrupt 54
Ooooooh... Wait...
Is this what interrupt-map is used for?
http://elinux.org/Device_Tree_Usage#Advanced_Interrupt_Mapping
Regards.
