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>
---
 drivers/irqchip/irq-gic-v3.c | 55 ++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index dbeb85677b08c..4a90dbf9daedb 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 +1798,60 @@ 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_info(struct irq_fwspec_info *info)
+{
+	struct irq_fwspec *fwspec = &info->fwspec;
+	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))
+		goto out;
+
+	/* 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:
+			goto out;
+		}
+
+		fw = of_node_to_fwnode(of_find_node_by_phandle(fwspec->param[3]));
+		if (!fw)
+			goto out;
+
+		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)
+			goto out;
+	} else {
+		mask = cpu_possible_mask;
+	}
+
+	info->affinity = mask;
+	info->flags = (IRQ_FWSPEC_INFO_FWSPEC_VALID |
+		       IRQ_FWSPEC_INFO_AFFINITY_VALID);
+out:
+	return 0;
+}
+
 static const struct irq_domain_ops gic_irq_domain_ops = {
 	.translate = gic_irq_domain_translate,
 	.alloc = gic_irq_domain_alloc,
 	.free = gic_irq_domain_free,
 	.select = gic_irq_domain_select,
+	.get_info = gic_irq_get_info,
 };
 
 static int partition_domain_translate(struct irq_domain *d,
@@ -1839,6 +1890,7 @@ static int partition_domain_translate(struct irq_domain *d,
 static const struct irq_domain_ops partition_domain_ops = {
 	.translate = partition_domain_translate,
 	.select = gic_irq_domain_select,
+	.get_info = gic_irq_get_info,
 };
 
 static bool gic_enable_quirk_msm8996(void *data)
@@ -2231,6 +2283,9 @@ static void __init gic_populate_ppi_partitions(struct device_node *gic_node)
 		part_idx++;
 	}
 
+	gic_data.parts = parts;
+	gic_data.nr_parts = nr_parts;
+
 	for (i = 0; i < gic_data.ppi_nr; i++) {
 		unsigned int irq;
 		struct partition_desc *desc;
-- 
2.39.2

On Mon, Sep 08 2025 at 17:31, Marc Zyngier wrote:
> +static int gic_irq_get_info(struct irq_fwspec_info *info)
> +{
> +	struct irq_fwspec *fwspec = &info->fwspec;
> +	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))
> +		goto out;

'goto out' to return 0? Seriously?

> +	/* 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:
> +			goto out;
> +		}
> +
> +		fw = of_node_to_fwnode(of_find_node_by_phandle(fwspec->param[3]));
> +		if (!fw)
> +			goto out;
> +
> +		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)
> +			goto out;
> +	} else {
> +		mask = cpu_possible_mask;
> +	}
> +
> +	info->affinity = mask;
> +	info->flags = (IRQ_FWSPEC_INFO_FWSPEC_VALID |
> +		       IRQ_FWSPEC_INFO_AFFINITY_VALID);

It's not really clear to me what the purpose
ofIRQ_FWSPEC_INFO_FWSPEC_VALID is. That firmware spec was handed in by
the caller, so it should be valid no matter what, no? 

Thanks,

        tglx