drivers: provide devm_platform_ioremap_resource_byname()

Provide a variant of devm_platform_ioremap_resource() that allows to
lookup resources from platform devices by name rather than by index.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20191022084318.22256-7-brgl@bgdev.plSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/driver-api/driver-model/devres.rst

@@ -319,6 +319,7 @@ IOMAP
   devm_ioremap_resource_wc()
   devm_platform_ioremap_resource() : calls devm_ioremap_resource() for platform device
   devm_platform_ioremap_resource_wc()
+  devm_platform_ioremap_resource_byname()
   devm_iounmap()
   pcim_iomap()
   pcim_iomap_regions()	: do request_region() and iomap() on multiple BARs

drivers/base/platform.c

@@ -95,6 +95,26 @@ void __iomem *devm_platform_ioremap_resource_wc(struct platform_device *pdev,
 	res = platform_get_resource(pdev, IORESOURCE_MEM, index);
 	return devm_ioremap_resource_wc(&pdev->dev, res);
 }
+
+/**
+ * devm_platform_ioremap_resource_byname - call devm_ioremap_resource for
+ *					   a platform device, retrieve the
+ *					   resource by name
+ *
+ * @pdev: platform device to use both for memory resource lookup as well as
+ *	  resource management
+ * @name: name of the resource
+ */
+void __iomem *
+devm_platform_ioremap_resource_byname(struct platform_device *pdev,
+				      const char *name)
+{
+	struct resource *res;
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, name);
+	return devm_ioremap_resource(&pdev->dev, res);
+}
+EXPORT_SYMBOL_GPL(devm_platform_ioremap_resource_byname);
 #endif /* CONFIG_HAS_IOMEM */
 
 /**

include/linux/platform_device.h

@@ -60,6 +60,9 @@ devm_platform_ioremap_resource(struct platform_device *pdev,
 extern void __iomem *
 devm_platform_ioremap_resource_wc(struct platform_device *pdev,
 				  unsigned int index);
+extern void __iomem *
+devm_platform_ioremap_resource_byname(struct platform_device *pdev,
+				      const char *name);
 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 *);