lib: devres: add a helper function for ioremap_wc

Implement a resource managed writecombine ioremap function.
Signed-off-by: Abhilash Kesavan <a.kesavan@samsung.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/driver-model/devres.txt

@@ -276,6 +276,7 @@ IOMAP
   devm_ioport_unmap()
   devm_ioremap()
   devm_ioremap_nocache()
+  devm_ioremap_wc()
   devm_ioremap_resource() : checks resource, requests memory region, ioremaps
   devm_iounmap()
   pcim_iomap()

include/linux/io.h

@@ -64,6 +64,8 @@ void __iomem *devm_ioremap(struct device *dev, resource_size_t offset,
 			   resource_size_t size);
 void __iomem *devm_ioremap_nocache(struct device *dev, resource_size_t offset,
 				   resource_size_t size);
+void __iomem *devm_ioremap_wc(struct device *dev, resource_size_t offset,
+				   resource_size_t size);
 void devm_iounmap(struct device *dev, void __iomem *addr);
 int check_signature(const volatile void __iomem *io_addr,
 			const unsigned char *signature, int length);

lib/devres.c

@@ -71,6 +71,34 @@ void __iomem *devm_ioremap_nocache(struct device *dev, resource_size_t offset,
 }
 EXPORT_SYMBOL(devm_ioremap_nocache);
 
+/**
+ * devm_ioremap_wc - Managed ioremap_wc()
+ * @dev: Generic device to remap IO address for
+ * @offset: BUS offset to map
+ * @size: Size of map
+ *
+ * Managed ioremap_wc().  Map is automatically unmapped on driver detach.
+ */
+void __iomem *devm_ioremap_wc(struct device *dev, resource_size_t offset,
+			      resource_size_t size)
+{
+	void __iomem **ptr, *addr;
+
+	ptr = devres_alloc(devm_ioremap_release, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return NULL;
+
+	addr = ioremap_wc(offset, size);
+	if (addr) {
+		*ptr = addr;
+		devres_add(dev, ptr);
+	} else
+		devres_free(ptr);
+
+	return addr;
+}
+EXPORT_SYMBOL(devm_ioremap_wc);
+
 /**
  * devm_iounmap - Managed iounmap()
  * @dev: Generic device to unmap for