Hi,
On Mon, Feb 11, 2019 at 11:01:12AM -0800, egran...@chromium.org wrote:
> From: Enrico Granata <egran...@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 <egran...@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
>
