Re: [PATCH v2 17/19] PCI: of_property: Add interrupt-controller property in PCI device nodes

Bjorn Helgaas
2024-06-06T19:26:14Z

On Mon, May 27, 2024 at 06:14:44PM +0200, Herve Codina wrote:
> PCI devices and bridges DT nodes created during the PCI scan are created
> with the interrupt-map property set to handle interrupts.
>
> In order to set this interrupt-map property at a specific level, a
> phandle to the parent interrupt controller is needed. On systems that
> are not fully described by a device-tree, the parent interrupt
> controller may be unavailable (i.e. not described by the device-tree).
>
> As mentioned in the [1], avoiding the use of the interrupt-map property
> and considering a PCI device as an interrupt controller itself avoid the
> use of a parent interrupt phandle.
>
> In that case, the PCI device itself as an interrupt controller is
> responsible for routing the interrupts described in the device-tree
> world (DT overlay) to the PCI interrupts.
>
> Add the 'interrupt-controller' property in the PCI device DT node.
>
> [1]: https://lore.kernel.org/lkml/CAL_Jsq+je7+9ATR=B6jXHjEJHjn24vQFs4Tvi9=vhDeK9n42Aw@mail.gmail.com/
>
> Signed-off-by: Herve Codina <herve.codina@bootlin.com>

No objection from me, but I'd like an ack/review from Rob.

> ---
> drivers/pci/of_property.c | 24 ++++++++++++++++++++++++
> 1 file changed, 24 insertions(+)
>
> diff --git a/drivers/pci/of_property.c b/drivers/pci/of_property.c
> index 03539e505372..5a0b98e69795 100644
> --- a/drivers/pci/of_property.c
> +++ b/drivers/pci/of_property.c
> @@ -183,6 +183,26 @@ static int of_pci_prop_interrupts(struct pci_dev *pdev,
> return of_changeset_add_prop_u32(ocs, np, "interrupts", (u32)pin);
> }
>
> +static int of_pci_prop_intr_ctrl(struct pci_dev *pdev, struct of_changeset *ocs,
> + struct device_node *np)
> +{
> + int ret;
> + u8 pin;
> +
> + ret = pci_read_config_byte(pdev, PCI_INTERRUPT_PIN, &pin);
> + if (ret != 0)
> + return ret;
> +
> + if (!pin)
> + return 0;
> +
> + ret = of_changeset_add_prop_u32(ocs, np, "#interrupt-cells", 1);
> + if (ret)
> + return ret;
> +
> + return of_changeset_add_prop_bool(ocs, np, "interrupt-controller");
> +}
> +
> static int of_pci_prop_intr_map(struct pci_dev *pdev, struct of_changeset *ocs,
> struct device_node *np)
> {
> @@ -336,6 +356,10 @@ int of_pci_add_properties(struct pci_dev *pdev, struct of_changeset *ocs,
> ret = of_pci_prop_intr_map(pdev, ocs, np);
> if (ret)
> return ret;
> + } else {
> + ret = of_pci_prop_intr_ctrl(pdev, ocs, np);
> + if (ret)
> + return ret;
> }
>
> ret = of_pci_prop_ranges(pdev, ocs, np);
> --
> 2.45.0
>