Hi, On Mon, Feb 11, 2019 at 11:01:12AM -0800, egranata@xxxxxxxxxxxx wrote: > From: Enrico Granata <egranata@xxxxxxxxxxxx> > > 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@xxxxxxxxxxxx> > --- > 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 >
