On Wed, Aug 28, 2019 at 10:34:10AM +0200, Thierry Reding wrote:
> From: Thierry Reding <treding@nvidia.com>
> 
> In some cases the interrupt line of a device is optional. Introduce a
> new platform_get_irq_optional() that works much like platform_get_irq()
> but does not output an error on failure to find the interrupt.
> 
> Signed-off-by: Thierry Reding <treding@nvidia.com>
> ---
>  drivers/base/platform.c         | 22 ++++++++++++++++++++++
>  include/linux/platform_device.h |  1 +
>  2 files changed, 23 insertions(+)
> 
> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> index 8ad701068c11..0dda6ade50fd 100644
> --- a/drivers/base/platform.c
> +++ b/drivers/base/platform.c
> @@ -192,6 +192,28 @@ int platform_get_irq(struct platform_device *dev, unsigned int num)
>  }
>  EXPORT_SYMBOL_GPL(platform_get_irq);
>  
> +/**
> + * platform_get_irq_optional - get an optional IRQ for a device
> + * @dev: platform device
> + * @num: IRQ number index
> + *
> + * Gets an IRQ for a platform device. Device drivers should check the return
> + * value for errors so as to not pass a negative integer value to the
> + * request_irq() APIs. This is the same as platform_get_irq(), except that it
> + * does not print an error message if an IRQ can not be obtained.
> + *
> + * Example:
> + *		int irq = platform_get_irq_optional(pdev, 0);
> + *		if (irq < 0)
> + *			return irq;
> + *
> + * Return: IRQ number on success, negative error number on failure.
> + */
> +int platform_get_irq_optional(struct platform_device *dev, unsigned int num)
> +{
> +	return __platform_get_irq(dev, num);
> +}

Oh my... this is embarrassing, but the kbuild test robot reported that
the second patch here fails to build because I forgot to export this
symbol. I've attached a patch that fixes it.

Thierry

> +
>  /**
>   * platform_irq_count - Count the number of IRQs a platform device uses
>   * @dev: platform device
> diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h
> index 37e15a935a42..35bc4355a9df 100644
> --- a/include/linux/platform_device.h
> +++ b/include/linux/platform_device.h
> @@ -58,6 +58,7 @@ extern void __iomem *
>  devm_platform_ioremap_resource(struct platform_device *pdev,
>  			       unsigned int index);
>  extern int platform_get_irq(struct platform_device *, unsigned int);
> +extern int platform_get_irq_optional(struct platform_device *, unsigned int);
>  extern int platform_irq_count(struct platform_device *);
>  extern struct resource *platform_get_resource_byname(struct platform_device *,
>  						     unsigned int,
> -- 
> 2.22.0
>