Re: [PATCH 15/17] pci: of_property: Add the interrupt-controller property in PCI device nodes

[Bjorn Helgaas]

In subject: s/pci:/PCI:/ to match history. s/Add the/Add/ for brevity.

On Tue, Apr 30, 2024 at 10:37:24AM +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).

Rewrap into one paragraph or add blank line to separate paragraphs.

> 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@xxxxxxxxxxxxxx/
> 
> Signed-off-by: Herve Codina <herve.codina@xxxxxxxxxxx>
> ---
>  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 c2c7334152bc..9f8b940029ed 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)
>  {
> @@ -334,6 +354,10 @@ 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);
> -- 
> 2.44.0
>