Patchwork [v2] driver: platform: Support parsing GpioInt 0 in platform_get_irq()

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Submitter egranata@chromium.org
Date Feb. 11, 2019, 7:01 p.m.
Message ID <20190211190112.209286-1-egranata@chromium.org>
Download mbox | patch
Permalink /patch/723257/
State New
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Comments

egranata@chromium.org - Feb. 11, 2019, 7:01 p.m.
From: Enrico Granata <egranata@chromium.org>

ACPI 5 added support for GpioInt resources as a way to provide
information about interrupts mediated via a GPIO controller.

Several device buses (e.g. SPI, I2C) have support for retrieving
an IRQ specified via this type of resource, and providing it
directly to the driver as an IRQ number.

This is not currently done for the platform drivers, as platform_get_irq()
does not try to parse GpioInt() resources. This requires drivers to
either have to support only one possible IRQ resource, or to have code
in place to try both as a failsafe.

While there is a possibility of ambiguity for devices that exposes
multiple IRQs, it is easy and feasible to support the common case
of devices that only expose one IRQ which would be of either type
depending on the underlying system's architecture.

This commit adds support for parsing a GpioInt resource in order
to fulfill a request for the index 0 IRQ for a platform device.

Signed-off-by: Enrico Granata <egranata@chromium.org>
---
Changes in v2:
 - only support IRQ index 0

 drivers/base/platform.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)
Dmitry Torokhov - Feb. 11, 2019, 7:25 p.m.
On Mon, Feb 11, 2019 at 11:01 AM <egranata@chromium.org> wrote:
>
> From: Enrico Granata <egranata@chromium.org>
>
> ACPI 5 added support for GpioInt resources as a way to provide
> information about interrupts mediated via a GPIO controller.
>
> Several device buses (e.g. SPI, I2C) have support for retrieving
> an IRQ specified via this type of resource, and providing it
> directly to the driver as an IRQ number.
>
> This is not currently done for the platform drivers, as platform_get_irq()
> does not try to parse GpioInt() resources. This requires drivers to
> either have to support only one possible IRQ resource, or to have code
> in place to try both as a failsafe.
>
> While there is a possibility of ambiguity for devices that exposes
> multiple IRQs, it is easy and feasible to support the common case
> of devices that only expose one IRQ which would be of either type
> depending on the underlying system's architecture.
>
> This commit adds support for parsing a GpioInt resource in order
> to fulfill a request for the index 0 IRQ for a platform device.
>
> Signed-off-by: Enrico Granata <egranata@chromium.org>

Yeah, this looks good to me.

Reviewed-by: Dmitry Torokhov <dtor@chromium.org>

> ---
> Changes in v2:
>  - only support IRQ index 0
>
>  drivers/base/platform.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> index 1c958eb33ef4d..0d3611cd1b3bc 100644
> --- a/drivers/base/platform.c
> +++ b/drivers/base/platform.c
> @@ -127,7 +127,20 @@ int platform_get_irq(struct platform_device *dev, unsigned int num)
>                 irqd_set_trigger_type(irqd, r->flags & IORESOURCE_BITS);
>         }
>
> -       return r ? r->start : -ENXIO;
> +       if (r)
> +               return r->start;
> +
> +       /*
> +        * For the index 0 interrupt, allow falling back to GpioInt
> +        * resources. While a device could have both Interrupt and GpioInt
> +        * resources, making this fallback ambiguous, in many common cases
> +        * the device will only expose one IRQ, and this fallback
> +        * allows a common code path across either kind of resource.
> +        */
> +       if (num == 0 && has_acpi_companion(&dev->dev))
> +               return acpi_dev_gpio_irq_get(ACPI_COMPANION(&dev->dev), num);
> +
> +       return -ENXIO;
>  #endif
>  }
>  EXPORT_SYMBOL_GPL(platform_get_irq);
> --
> 2.20.1.791.gb4d0f1c61a-goog
>
Hans de Goede - Feb. 12, 2019, 7:29 a.m.
Hi,

On 11-02-19 20:01, egranata@chromium.org wrote:
> From: Enrico Granata <egranata@chromium.org>
> 
> ACPI 5 added support for GpioInt resources as a way to provide
> information about interrupts mediated via a GPIO controller.
> 
> Several device buses (e.g. SPI, I2C) have support for retrieving
> an IRQ specified via this type of resource, and providing it
> directly to the driver as an IRQ number.
> 
> This is not currently done for the platform drivers, as platform_get_irq()
> does not try to parse GpioInt() resources. This requires drivers to
> either have to support only one possible IRQ resource, or to have code
> in place to try both as a failsafe.
> 
> While there is a possibility of ambiguity for devices that exposes
> multiple IRQs, it is easy and feasible to support the common case
> of devices that only expose one IRQ which would be of either type
> depending on the underlying system's architecture.
> 
> This commit adds support for parsing a GpioInt resource in order
> to fulfill a request for the index 0 IRQ for a platform device.
> 
> Signed-off-by: Enrico Granata <egranata@chromium.org>

Looks good to me:

Acked-by: Hans de Goede <hdegoede@redhat.com>

Regards,

Hans


> ---
> Changes in v2:
>   - only support IRQ index 0
> 
>   drivers/base/platform.c | 15 ++++++++++++++-
>   1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> index 1c958eb33ef4d..0d3611cd1b3bc 100644
> --- a/drivers/base/platform.c
> +++ b/drivers/base/platform.c
> @@ -127,7 +127,20 @@ int platform_get_irq(struct platform_device *dev, unsigned int num)
>   		irqd_set_trigger_type(irqd, r->flags & IORESOURCE_BITS);
>   	}
>   
> -	return r ? r->start : -ENXIO;
> +	if (r)
> +		return r->start;
> +
> +	/*
> +	 * For the index 0 interrupt, allow falling back to GpioInt
> +	 * resources. While a device could have both Interrupt and GpioInt
> +	 * resources, making this fallback ambiguous, in many common cases
> +	 * the device will only expose one IRQ, and this fallback
> +	 * allows a common code path across either kind of resource.
> +	 */
> +	if (num == 0 && has_acpi_companion(&dev->dev))
> +		return acpi_dev_gpio_irq_get(ACPI_COMPANION(&dev->dev), num);
> +
> +	return -ENXIO;
>   #endif
>   }
>   EXPORT_SYMBOL_GPL(platform_get_irq);
>
Mika Westerberg - Feb. 12, 2019, 9:08 a.m.
On Mon, Feb 11, 2019 at 11:01:12AM -0800, egranata@chromium.org wrote:
> From: Enrico Granata <egranata@chromium.org>
> 
> ACPI 5 added support for GpioInt resources as a way to provide
> information about interrupts mediated via a GPIO controller.
> 
> Several device buses (e.g. SPI, I2C) have support for retrieving
> an IRQ specified via this type of resource, and providing it
> directly to the driver as an IRQ number.
> 
> This is not currently done for the platform drivers, as platform_get_irq()
> does not try to parse GpioInt() resources. This requires drivers to
> either have to support only one possible IRQ resource, or to have code
> in place to try both as a failsafe.
> 
> While there is a possibility of ambiguity for devices that exposes
> multiple IRQs, it is easy and feasible to support the common case
> of devices that only expose one IRQ which would be of either type
> depending on the underlying system's architecture.
> 
> This commit adds support for parsing a GpioInt resource in order
> to fulfill a request for the index 0 IRQ for a platform device.
> 
> Signed-off-by: Enrico Granata <egranata@chromium.org>

Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Rafael J. Wysocki - Feb. 12, 2019, 9:18 a.m.
On Mon, Feb 11, 2019 at 8:01 PM <egranata@chromium.org> wrote:
>
> From: Enrico Granata <egranata@chromium.org>
>
> ACPI 5 added support for GpioInt resources as a way to provide
> information about interrupts mediated via a GPIO controller.
>
> Several device buses (e.g. SPI, I2C) have support for retrieving
> an IRQ specified via this type of resource, and providing it
> directly to the driver as an IRQ number.
>
> This is not currently done for the platform drivers, as platform_get_irq()
> does not try to parse GpioInt() resources. This requires drivers to
> either have to support only one possible IRQ resource, or to have code
> in place to try both as a failsafe.
>
> While there is a possibility of ambiguity for devices that exposes
> multiple IRQs, it is easy and feasible to support the common case
> of devices that only expose one IRQ which would be of either type
> depending on the underlying system's architecture.
>
> This commit adds support for parsing a GpioInt resource in order
> to fulfill a request for the index 0 IRQ for a platform device.
>
> Signed-off-by: Enrico Granata <egranata@chromium.org>

Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

> ---
> Changes in v2:
>  - only support IRQ index 0
>
>  drivers/base/platform.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> index 1c958eb33ef4d..0d3611cd1b3bc 100644
> --- a/drivers/base/platform.c
> +++ b/drivers/base/platform.c
> @@ -127,7 +127,20 @@ int platform_get_irq(struct platform_device *dev, unsigned int num)
>                 irqd_set_trigger_type(irqd, r->flags & IORESOURCE_BITS);
>         }
>
> -       return r ? r->start : -ENXIO;
> +       if (r)
> +               return r->start;
> +
> +       /*
> +        * For the index 0 interrupt, allow falling back to GpioInt
> +        * resources. While a device could have both Interrupt and GpioInt
> +        * resources, making this fallback ambiguous, in many common cases
> +        * the device will only expose one IRQ, and this fallback
> +        * allows a common code path across either kind of resource.
> +        */
> +       if (num == 0 && has_acpi_companion(&dev->dev))
> +               return acpi_dev_gpio_irq_get(ACPI_COMPANION(&dev->dev), num);
> +
> +       return -ENXIO;
>  #endif
>  }
>  EXPORT_SYMBOL_GPL(platform_get_irq);
> --
> 2.20.1.791.gb4d0f1c61a-goog
>
Andy Shevchenko - Feb. 12, 2019, 12:46 p.m.
On Mon, Feb 11, 2019 at 11:01:12AM -0800, egranata@chromium.org wrote:
> From: Enrico Granata <egranata@chromium.org>
> 
> ACPI 5 added support for GpioInt resources as a way to provide
> information about interrupts mediated via a GPIO controller.
> 
> Several device buses (e.g. SPI, I2C) have support for retrieving
> an IRQ specified via this type of resource, and providing it
> directly to the driver as an IRQ number.
> 
> This is not currently done for the platform drivers, as platform_get_irq()
> does not try to parse GpioInt() resources. This requires drivers to
> either have to support only one possible IRQ resource, or to have code
> in place to try both as a failsafe.
> 
> While there is a possibility of ambiguity for devices that exposes
> multiple IRQs, it is easy and feasible to support the common case
> of devices that only expose one IRQ which would be of either type
> depending on the underlying system's architecture.
> 
> This commit adds support for parsing a GpioInt resource in order
> to fulfill a request for the index 0 IRQ for a platform device.
> 

Yes, let's go this way as a compromise to get major of the cases working.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

> Signed-off-by: Enrico Granata <egranata@chromium.org>
> ---
> Changes in v2:
>  - only support IRQ index 0
> 
>  drivers/base/platform.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> index 1c958eb33ef4d..0d3611cd1b3bc 100644
> --- a/drivers/base/platform.c
> +++ b/drivers/base/platform.c
> @@ -127,7 +127,20 @@ int platform_get_irq(struct platform_device *dev, unsigned int num)
>  		irqd_set_trigger_type(irqd, r->flags & IORESOURCE_BITS);
>  	}
>  
> -	return r ? r->start : -ENXIO;
> +	if (r)
> +		return r->start;
> +
> +	/*
> +	 * For the index 0 interrupt, allow falling back to GpioInt
> +	 * resources. While a device could have both Interrupt and GpioInt
> +	 * resources, making this fallback ambiguous, in many common cases
> +	 * the device will only expose one IRQ, and this fallback
> +	 * allows a common code path across either kind of resource.
> +	 */
> +	if (num == 0 && has_acpi_companion(&dev->dev))
> +		return acpi_dev_gpio_irq_get(ACPI_COMPANION(&dev->dev), num);
> +
> +	return -ENXIO;
>  #endif
>  }
>  EXPORT_SYMBOL_GPL(platform_get_irq);
> -- 
> 2.20.1.791.gb4d0f1c61a-goog
>
Brian Norris - Feb. 20, 2019, 6:05 p.m.
Hi,

On Mon, Feb 11, 2019 at 11:01:12AM -0800, egranata@chromium.org wrote:
> From: Enrico Granata <egranata@chromium.org>
> 
> ACPI 5 added support for GpioInt resources as a way to provide
> information about interrupts mediated via a GPIO controller.
> 
> Several device buses (e.g. SPI, I2C) have support for retrieving
> an IRQ specified via this type of resource, and providing it
> directly to the driver as an IRQ number.
> 
> This is not currently done for the platform drivers, as platform_get_irq()
> does not try to parse GpioInt() resources. This requires drivers to
> either have to support only one possible IRQ resource, or to have code
> in place to try both as a failsafe.
> 
> While there is a possibility of ambiguity for devices that exposes
> multiple IRQs, it is easy and feasible to support the common case
> of devices that only expose one IRQ which would be of either type
> depending on the underlying system's architecture.
> 
> This commit adds support for parsing a GpioInt resource in order
> to fulfill a request for the index 0 IRQ for a platform device.
> 
> Signed-off-by: Enrico Granata <egranata@chromium.org>
> ---
> Changes in v2:
>  - only support IRQ index 0
> 
>  drivers/base/platform.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> index 1c958eb33ef4d..0d3611cd1b3bc 100644
> --- a/drivers/base/platform.c
> +++ b/drivers/base/platform.c
> @@ -127,7 +127,20 @@ int platform_get_irq(struct platform_device *dev, unsigned int num)
>  		irqd_set_trigger_type(irqd, r->flags & IORESOURCE_BITS);
>  	}
>  
> -	return r ? r->start : -ENXIO;
> +	if (r)
> +		return r->start;
> +
> +	/*
> +	 * For the index 0 interrupt, allow falling back to GpioInt
> +	 * resources. While a device could have both Interrupt and GpioInt
> +	 * resources, making this fallback ambiguous, in many common cases
> +	 * the device will only expose one IRQ, and this fallback
> +	 * allows a common code path across either kind of resource.
> +	 */
> +	if (num == 0 && has_acpi_companion(&dev->dev))
> +		return acpi_dev_gpio_irq_get(ACPI_COMPANION(&dev->dev), num);

For ACPI devices, this changes the return code for a missing interrupt
0 from ENXIO to ENOENT, because acpi_dev_gpio_irq_get() uses ENOENT
instead of ENXIO. While ENXIO isn't exactly documented as the *specific*
error code for a missing interrupt in platform_get_irq(), there are
definitely drivers out there that are looking specifically for ENXIO
(grepping the tree finds several Rockchip platform drivers and a few
ethernet drivers at a minimum). And it also incidentally broke some
usage of the very driver you were trying to support
(drivers/platform/chrome/cros_ec_lpc.c).

I suspect a good strategy here would be to check
acpi_dev_gpio_irq_get()'s return codes here with something like:

	if (ret > 0 || ret == -EPROBE_DEFER)
		return ret;
	return -ENXIO;

Although, the gpiolib functions embedded in there also can return EIO,
so maybe something like this is better?

	if (ret == -ENOENT || ret == 0)
		return -ENXIO;
	return ret;

I'm kinda unsure what to do with error codes besides PROBE_DEFER or
"missing", since most users don't really have it in their mind that
platform_get_irq() can fail with EIO or similar.

Brian

> +
> +	return -ENXIO;
>  #endif
>  }
>  EXPORT_SYMBOL_GPL(platform_get_irq);
> -- 
> 2.20.1.791.gb4d0f1c61a-goog
>
egranata@google.com - Feb. 21, 2019, 6:58 p.m.
Thanks for catching that and sorry for the delayed response, I was on vacation.

I think your analysis makes sense. I would personally lean towards the
former suggestion (keeping the change localized to the return value of
platform_get_irq() which is the function that apparently has an
informal contract about returning -ENXIO specifically).

I am happy to post a PATCH v3 to that effect if this seems amenable.

Thanks

Enrico Granata | egranata@google.com | ChromeOS | MTV1600


On Wed, Feb 20, 2019 at 10:05 AM Brian Norris <briannorris@chromium.org> wrote:
>
> Hi,
>
> On Mon, Feb 11, 2019 at 11:01:12AM -0800, egranata@chromium.org wrote:
> > From: Enrico Granata <egranata@chromium.org>
> >
> > ACPI 5 added support for GpioInt resources as a way to provide
> > information about interrupts mediated via a GPIO controller.
> >
> > Several device buses (e.g. SPI, I2C) have support for retrieving
> > an IRQ specified via this type of resource, and providing it
> > directly to the driver as an IRQ number.
> >
> > This is not currently done for the platform drivers, as platform_get_irq()
> > does not try to parse GpioInt() resources. This requires drivers to
> > either have to support only one possible IRQ resource, or to have code
> > in place to try both as a failsafe.
> >
> > While there is a possibility of ambiguity for devices that exposes
> > multiple IRQs, it is easy and feasible to support the common case
> > of devices that only expose one IRQ which would be of either type
> > depending on the underlying system's architecture.
> >
> > This commit adds support for parsing a GpioInt resource in order
> > to fulfill a request for the index 0 IRQ for a platform device.
> >
> > Signed-off-by: Enrico Granata <egranata@chromium.org>
> > ---
> > Changes in v2:
> >  - only support IRQ index 0
> >
> >  drivers/base/platform.c | 15 ++++++++++++++-
> >  1 file changed, 14 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> > index 1c958eb33ef4d..0d3611cd1b3bc 100644
> > --- a/drivers/base/platform.c
> > +++ b/drivers/base/platform.c
> > @@ -127,7 +127,20 @@ int platform_get_irq(struct platform_device *dev, unsigned int num)
> >               irqd_set_trigger_type(irqd, r->flags & IORESOURCE_BITS);
> >       }
> >
> > -     return r ? r->start : -ENXIO;
> > +     if (r)
> > +             return r->start;
> > +
> > +     /*
> > +      * For the index 0 interrupt, allow falling back to GpioInt
> > +      * resources. While a device could have both Interrupt and GpioInt
> > +      * resources, making this fallback ambiguous, in many common cases
> > +      * the device will only expose one IRQ, and this fallback
> > +      * allows a common code path across either kind of resource.
> > +      */
> > +     if (num == 0 && has_acpi_companion(&dev->dev))
> > +             return acpi_dev_gpio_irq_get(ACPI_COMPANION(&dev->dev), num);
>
> For ACPI devices, this changes the return code for a missing interrupt
> 0 from ENXIO to ENOENT, because acpi_dev_gpio_irq_get() uses ENOENT
> instead of ENXIO. While ENXIO isn't exactly documented as the *specific*
> error code for a missing interrupt in platform_get_irq(), there are
> definitely drivers out there that are looking specifically for ENXIO
> (grepping the tree finds several Rockchip platform drivers and a few
> ethernet drivers at a minimum). And it also incidentally broke some
> usage of the very driver you were trying to support
> (drivers/platform/chrome/cros_ec_lpc.c).
>
> I suspect a good strategy here would be to check
> acpi_dev_gpio_irq_get()'s return codes here with something like:
>
>         if (ret > 0 || ret == -EPROBE_DEFER)
>                 return ret;
>         return -ENXIO;
>
> Although, the gpiolib functions embedded in there also can return EIO,
> so maybe something like this is better?
>
>         if (ret == -ENOENT || ret == 0)
>                 return -ENXIO;
>         return ret;
>
> I'm kinda unsure what to do with error codes besides PROBE_DEFER or
> "missing", since most users don't really have it in their mind that
> platform_get_irq() can fail with EIO or similar.
>
> Brian
>
> > +
> > +     return -ENXIO;
> >  #endif
> >  }
> >  EXPORT_SYMBOL_GPL(platform_get_irq);
> > --
> > 2.20.1.791.gb4d0f1c61a-goog
> >

Patch

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 1c958eb33ef4d..0d3611cd1b3bc 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -127,7 +127,20 @@  int platform_get_irq(struct platform_device *dev, unsigned int num)
 		irqd_set_trigger_type(irqd, r->flags & IORESOURCE_BITS);
 	}
 
-	return r ? r->start : -ENXIO;
+	if (r)
+		return r->start;
+
+	/*
+	 * For the index 0 interrupt, allow falling back to GpioInt
+	 * resources. While a device could have both Interrupt and GpioInt
+	 * resources, making this fallback ambiguous, in many common cases
+	 * the device will only expose one IRQ, and this fallback
+	 * allows a common code path across either kind of resource.
+	 */
+	if (num == 0 && has_acpi_companion(&dev->dev))
+		return acpi_dev_gpio_irq_get(ACPI_COMPANION(&dev->dev), num);
+
+	return -ENXIO;
 #endif
 }
 EXPORT_SYMBOL_GPL(platform_get_irq);