Re: [PATCH v2 3/8] irqchip/apple-aic: Add cpumasks for E and P cores

From: Hector Martin <marcan@marcan.st>
To: Marc Zyngier <maz@kernel.org>,
	linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>,
	Will Deacon <will@kernel.org>, Sven Peter <sven@svenpeter.dev>,
	Alyssa Rosenzweig <alyssa@rosenzweig.io>,
	Rob Herring <robh+dt@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Dougall <dougallj@gmail.com>,
	kernel-team@android.com
Subject: Re: [PATCH v2 3/8] irqchip/apple-aic: Add cpumasks for E and P cores
Date: Sun, 12 Dec 2021 16:30:20 +0900	[thread overview]
Message-ID: <8bb14854-3377-4901-aaba-1a124c57cbec@marcan.st> (raw)
In-Reply-To: <20211201134909.390490-4-maz@kernel.org>

On 01/12/2021 22.49, Marc Zyngier wrote:
> In order to be able to tell the core IRQ code about the affinity
> of the PMU interrupt in later patches, compute the cpumasks of the
> P and E cores at boot time.
> 
> This relies on the affinity scheme used by the vendor, which seems
> to work for the couple of SoCs that are out in the wild.
> 
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
>   drivers/irqchip/irq-apple-aic.c | 14 ++++++++++++++
>   1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/irqchip/irq-apple-aic.c b/drivers/irqchip/irq-apple-aic.c
> index 3759dc36cc8f..30ca80ccda8b 100644
> --- a/drivers/irqchip/irq-apple-aic.c
> +++ b/drivers/irqchip/irq-apple-aic.c
> @@ -177,6 +177,8 @@ struct aic_irq_chip {
>   	void __iomem *base;
>   	struct irq_domain *hw_domain;
>   	struct irq_domain *ipi_domain;
> +	struct cpumask ecore_mask;
> +	struct cpumask pcore_mask;
>   	int nr_hw;
>   	int ipi_hwirq;
>   };
> @@ -200,6 +202,11 @@ static void aic_ic_write(struct aic_irq_chip *ic, u32 reg, u32 val)
>   	writel_relaxed(val, ic->base + reg);
>   }
>   
> +static bool __is_pcore(u64 mpidr)
> +{
> +	return MPIDR_AFFINITY_LEVEL(mpidr, 2) == 1;
> +}
> +
>   /*
>    * IRQ irqchip
>    */
> @@ -833,6 +840,13 @@ static int __init aic_of_ic_init(struct device_node *node, struct device_node *p
>   		return -ENODEV;
>   	}
>   
> +	for_each_possible_cpu(i) {
> +		if (__is_pcore(cpu_logical_map(i)))
> +			cpumask_set_cpu(i, &irqc->pcore_mask);
> +		else
> +			cpumask_set_cpu(i, &irqc->ecore_mask);
> +	}
> +
>   	set_handle_irq(aic_handle_irq);
>   	set_handle_fiq(aic_handle_fiq);
>   
> 

I'm okay with this approach, but if we want to be more explicit about 
the affinities, maybe something like apple,pmu-irq-index in the CPU 
nodes? Then we can either start at a higher FIQ offset for these (in 
case we need to add more FIQs in the future), or just make up a new 
AIC_PMU top level interrupt type and start at 0.

-- 
Hector Martin (marcan@marcan.st)
Public Key: https://mrcn.st/pub