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Create pci_routing::Pin::from_pci_interrupt_pin convenience fn. #359

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Merged
martin-hughes merged 2 commits into from
Sep 21, 2026
Merged

Create pci_routing::Pin::from_pci_interrupt_pin convenience fn. #359

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bf4ef0c
Create `pci_routing::Pin::from_pci_interrupt_pin` convenience fn.
ChocolateLoverRaj Sep 19, 2026
0c19597
Add Pin::from_prt_package_pin and improve docs
ChocolateLoverRaj Sep 20, 2026
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41 changes: 36 additions & 5 deletions src/aml/pci_routing.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,39 @@ pub enum Pin {
IntD,
}

#[derive(Debug, Clone, Copy)]
pub struct InvalidPciInterruptPinError(pub u8);

@martin-hughes martin-hughes Sep 20, 2026

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I'm of two minds about this. I feel like it should be a "true" error (impl Error) for similar reasons to those in this article, but I also see that AmlError doesn't do this.

It's probably fine to leave as it is, but @IsaacWoods, any thoughts?

@IsaacWoods IsaacWoods Sep 21, 2026

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I think the reason for this is purely me ignoring Error while it was std-only for a long while and then me being out of date! I definitely don't see any reason we shouldn't be implementing it for both errors like this and very likely for AmlError.

Doesn't necessarily need to block this PR, but up to you.

@martin-hughes martin-hughes Sep 21, 2026

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👍 Quite happy to leave it and reconsider if (when!) we think about errors a bit more


#[derive(Debug, Clone, Copy)]
pub struct InvalidPrtPackagePin(pub u8);

impl Pin {
/// The [pin byte in the PCI configuration space](https://wiki.osdev.org/PCI#Header_Type_0x0) represents INTA-INTD as 1-4.
/// 0 means that the PCI device doesn't use an interrupt pin, in which case `Ok(None)` will be returned.
pub fn from_pci_interrupt_pin(pin: u8) -> Result<Option<Self>, InvalidPciInterruptPinError> {
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match pin {
0 => Ok(None),
1 => Ok(Some(Self::IntA)),
2 => Ok(Some(Self::IntB)),
3 => Ok(Some(Self::IntC)),
4 => Ok(Some(Self::IntD)),
pin => Err(InvalidPciInterruptPinError(pin)),
}
}

/// The [ACPI PCI Routing Table](https://uefi.org/specs/ACPI/6.6/06_Device_Configuration.html#prt-pci-routing-table)
/// represents INTA-INTD as 0-3.
pub fn from_prt_package_pin(pin: u8) -> Result<Self, InvalidPrtPackagePin> {
match pin {
0 => Ok(Self::IntA),
1 => Ok(Self::IntB),
2 => Ok(Self::IntC),
3 => Ok(Self::IntD),
pin => Err(InvalidPrtPackagePin(pin)),
}
}
}

#[derive(Debug)]
pub enum PciRouteType {
/// The interrupt is hard-coded to a specific GSI
Expand Down Expand Up @@ -97,13 +130,11 @@ impl PciRoutingTable {
};
let device = address.get_bits(16..32).try_into().map_err(|_| AmlError::PrtInvalidAddress)?;
let function = address.get_bits(0..16).try_into().map_err(|_| AmlError::PrtInvalidAddress)?;
let pin = match *pin_package[1] {
Object::Integer(0) => Pin::IntA,
Object::Integer(1) => Pin::IntB,
Object::Integer(2) => Pin::IntC,
Object::Integer(3) => Pin::IntD,
let pin_byte = match *pin_package[1] {
Object::Integer(byte) => byte as u8,
_ => return Err(AmlError::PrtInvalidPin),
};
let pin = Pin::from_prt_package_pin(pin_byte).map_err(|_| AmlError::PrtInvalidPin)?;

/*
* A `NamePath` source is a reference to a name that we haven't resolved yet. We
Expand Down
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