Re: [PATCH v2 05/25] irqchip/gic-v3: Add FW info retrieval support

Jonathan Cameron
2025-09-16T15:34:18Z

On Mon, 15 Sep 2025 09:56:42 +0100
Marc Zyngier <maz@kernel.org> wrote:

> Plug the new .get_info() callback into the GICv3 core driver,
> using some of the existing PPI affinity handling infrastructure.
>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
Hi Marc,

Yet another trivial comment. It's one of those days it seems :)

> ---
> drivers/irqchip/irq-gic-v3.c | 53 ++++++++++++++++++++++++++++++++++++
> 1 file changed, 53 insertions(+)
>
> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
> index dbeb85677b08c..71c278ddd1e39 100644
> --- a/drivers/irqchip/irq-gic-v3.c
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -69,6 +69,8 @@ struct gic_chip_data {
> bool has_rss;
> unsigned int ppi_nr;
> struct partition_desc **ppi_descs;
> + struct partition_affinity *parts;
> + unsigned int nr_parts;
> };
>
> #define T241_CHIPS_MAX 4
> @@ -1796,11 +1798,58 @@ static int gic_irq_domain_select(struct irq_domain *d,
> return d == partition_get_domain(gic_data.ppi_descs[ppi_idx]);
> }
>
> +static int gic_irq_get_fwspec_info(struct irq_fwspec *fwspec, struct irq_fwspec_info *info)
> +{
> + const struct cpumask *mask = NULL;
> +
> + info->flags = 0;
> + info->affinity = NULL;
> +
> + /* ACPI is not capable of describing PPI affinity -- yet */
> + if (!is_of_node(fwspec->fwnode))
> + return 0;
> +
> + /* If the specifier provides an affinity, use it */
> + if (fwspec->param_count == 4 && fwspec->param[3]) {
> + struct fwnode_handle *fw;
> +
> + switch (fwspec->param[0]) {
> + case 1: /* PPI */
> + case 3: /* EPPI */
> + break;
> + default:
> + return 0;
> + }
> +
> + fw = of_node_to_fwnode(of_find_node_by_phandle(fwspec->param[3]));

of_node_to_fwnode() has a note that says it'll be removed in the merge window.
It was enough of an oddity I wondered why it existed.

Of course it did say it would be removed in the previous merge window and wasn't...
Probably want of_fwnode_handle()

> + if (!fw)
> + return -ENOENT;
> +
> + for (int i = 0; i < gic_data.nr_parts; i++) {
> + if (gic_data.parts[i].partition_id == fw) {
> + mask = &gic_data.parts[i].mask;
> + break;
> + }
> + }
> +
> + if (!mask)
> + return -ENOENT;
> + } else {
> + mask = cpu_possible_mask;
> + }
> +
> + info->affinity = mask;
> + info->flags = IRQ_FWSPEC_INFO_AFFINITY_VALID;
> +
> + return 0;