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

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Message-ID: <20250916163413.000062f0@huawei.com>
Date: Tue, 16 Sep 2025 16:34:13 +0100
From: Jonathan Cameron <jonathan.cameron@...wei.com>
To: Marc Zyngier <maz@...nel.org>
CC: <linux-kernel@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-acpi@...r.kernel.org>, Thomas Gleixner <tglx@...utronix.de>, "Mark
 Rutland" <mark.rutland@....com>, Will Deacon <will@...nel.org>, "Rafael J.
 Wysocki" <rafael@...nel.org>, Rob Herring <robh@...nel.org>, "Saravana
 Kannan" <saravanak@...gle.com>, Greg Kroah-Hartman
	<gregkh@...uxfoundation.org>, Sven Peter <sven@...nel.org>, Janne Grunau
	<j@...nau.net>, Suzuki K Poulose <suzuki.poulose@....com>, James Clark
	<james.clark@...aro.org>
Subject: Re: [PATCH v2 05/25] irqchip/gic-v3: Add FW info retrieval support

On Mon, 15 Sep 2025 09:56:42 +0100
Marc Zyngier <maz@...nel.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@...nel.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;