driver core: platform: Add an error message to platform_get_irq*()

A grep of the kernel shows that many drivers print an error message if
they fail to get the irq they're looking for. Furthermore, those drivers
all decide to print the device name, or not, and the irq they were
requesting, or not, etc. Let's consolidate all these error messages into
the API itself, allowing us to get rid of the error messages in each
driver.

Cc: Rob Herring <robh@kernel.org>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Javier Martinez Canillas <javierm@redhat.com>
Cc: Andrzej Hajda <a.hajda@samsung.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Russell King - ARM Linux <linux@armlinux.org.uk>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Markus Elfring <Markus.Elfring@web.de>
Reviewed-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: NAndy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: NStephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20190730053845.126834-2-swboyd@chromium.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/platform.c

@@ -99,12 +99,7 @@ void __iomem *devm_platform_ioremap_resource(struct platform_device *pdev,
 EXPORT_SYMBOL_GPL(devm_platform_ioremap_resource);
 #endif /* CONFIG_HAS_IOMEM */
 
-/**
- * platform_get_irq - get an IRQ for a device
- * @dev: platform device
- * @num: IRQ number index
- */
-int platform_get_irq(struct platform_device *dev, unsigned int num)
+static int __platform_get_irq(struct platform_device *dev, unsigned int num)
 {
 #ifdef CONFIG_SPARC
 	/* sparc does not have irqs represented as IORESOURCE_IRQ resources */
@@ -163,6 +158,33 @@ int platform_get_irq(struct platform_device *dev, unsigned int num)
 	return -ENXIO;
 #endif
 }
+
+/**
+ * platform_get_irq - get an IRQ for a device
+ * @dev: platform device
+ * @num: IRQ number index
+ *
+ * Gets an IRQ for a platform device and prints an error message if finding the
+ * IRQ fails. Device drivers should check the return value for errors so as to
+ * not pass a negative integer value to the request_irq() APIs.
+ *
+ * Example:
+ *		int irq = platform_get_irq(pdev, 0);
+ *		if (irq < 0)
+ *			return irq;
+ *
+ * Return: IRQ number on success, negative error number on failure.
+ */
+int platform_get_irq(struct platform_device *dev, unsigned int num)
+{
+	int ret;
+
+	ret = __platform_get_irq(dev, num);
+	if (ret < 0 && ret != -EPROBE_DEFER)
+		dev_err(&dev->dev, "IRQ index %u not found\n", num);
+
+	return ret;
+}
 EXPORT_SYMBOL_GPL(platform_get_irq);
 
 /**
@@ -175,7 +197,7 @@ int platform_irq_count(struct platform_device *dev)
 {
 	int ret, nr = 0;
 
-	while ((ret = platform_get_irq(dev, nr)) >= 0)
+	while ((ret = __platform_get_irq(dev, nr)) >= 0)
 		nr++;
 
 	if (ret == -EPROBE_DEFER)
@@ -228,7 +250,11 @@ int platform_get_irq_byname(struct platform_device *dev, const char *name)
 	}
 
 	r = platform_get_resource_byname(dev, IORESOURCE_IRQ, name);
-	return r ? r->start : -ENXIO;
+	if (r)
+		return r->start;
+
+	dev_err(&dev->dev, "IRQ %s not found\n", name);
+	return -ENXIO;
 }
 EXPORT_SYMBOL_GPL(platform_get_irq_byname);