[PATCH 1/2] driver core: platform: Introduce platform_get_irq_optional()

[Thierry Reding <thierry.reding@gmail.com>]

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);
+}
+
 /**
  * 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