linux-kernel - Re: [PATCH v1 3/6] of: irq: add wake capable bit to of_irq

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Message-ID: <20231213221959.GC2115075-robh@kernel.org>
Date:   Wed, 13 Dec 2023 16:19:59 -0600
From:   Rob Herring <robh@...nel.org>
To:     Mark Hasemeyer <markhas@...omium.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Raul Rangel <rrangel@...omium.org>,
        Frank Rowand <frowand.list@...il.com>,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v1 3/6] of: irq: add wake capable bit to of_irq_resource()

On Wed, Dec 13, 2023 at 11:00:21AM -0700, Mark Hasemeyer wrote:
> Add wake capability information to the irq resource. Wake capability is
> assumed based on conventions provided in the devicetree wakeup-source
> binding documentation. An interrupt is considered wake capable if the
> following are true:
> 1. a wakeup-source property exits in the same device node as the
>    interrupt.
> 2. No dedicated irq is defined, or the irq is marked as dedicated by
>    setting its interrupt-name to "wakeup".
> 
> The wakeup-source documentation states that dedicated interrupts can use
> device specific interrupt names and device drivers are still welcome to
> use their own naming schemes. This api is provided as a helper if one is
> willing to conform to the above conventions.
> 
> The ACPI subsystems already provides similar apis that allow one to
> query the wake capability of an irq. This brings feature parity to the
> devicetree.
> 
> Signed-off-by: Mark Hasemeyer <markhas@...omium.org>
> ---
> 
>  drivers/of/irq.c | 30 ++++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
> 
> diff --git a/drivers/of/irq.c b/drivers/of/irq.c
> index 174900072c18c..633711bc32953 100644
> --- a/drivers/of/irq.c
> +++ b/drivers/of/irq.c
> @@ -383,11 +383,39 @@ int of_irq_parse_one(struct device_node *device, int index, struct of_phandle_ar
>  }
>  EXPORT_SYMBOL_GPL(of_irq_parse_one);
>  
> +/**
> + * __of_irq_wake_capable - Determine whether a given irq index is wake capable
> + *
> + * The irq is considered wake capable if the following are true:
> + * 1. wakeup-source property exists
> + * 2. no dedicated wakeirq exists OR provided irq index is a dedicated wakeirq
> + *
> + * This logic assumes the provided irq index is valid.
> + *
> + * @dev: pointer to device tree node
> + * @index: zero-based index of the irq
> + * Return: True if provided irq index for #dev is wake capable. False otherwise.
> + */
> +static bool __of_irq_wake_capable(const struct device_node *dev, int index)
> +{
> +	int wakeindex;
> +
> +	if (!of_property_read_bool(dev, "wakeup-source"))
> +		return false;
> +
> +	wakeindex = of_property_match_string(dev, "interrupt-names", "wakeup");
> +	return wakeindex < 0 || wakeindex == index;

If a device has multiple interrupts, but none named "wakeup" you are 
saying all the interrupts are wakeup capable. That's not right though. 
Only the device knows which interrupts are wakeup capable. You need:

return wakeindex >= 0 && wakeindex == index;

Rob