of: Provide a function to request and map memory

A call to of_iomap does not request the memory region. This patch adds the
function of_io_request_and_map which requests the memory region before
mapping it.

Signed-off-by: Matthias Brugger <[e-mail]>
Suggested-by: Thomas Gleixner <[e-mail]>
Suggested-by: Rob Herring <[e-mail]>
Acked-by: Rob Herring <[e-mail]>
Signed-off-by: Daniel Lezcano <[e-mail]>

drivers/of/address.c

···
 }
 EXPORT_SYMBOL(of_iomap);
 
+/*
+ * of_io_request_and_map - Requests a resource and maps the memory mapped IO
+ *			   for a given device_node
+ * @device:	the device whose io range will be mapped
+ * @index:	index of the io range
+ * @name:	name of the resource
+ *
+ * Returns a pointer to the requested and mapped memory or an ERR_PTR() encoded
+ * error code on failure. Usage example:
+ *
+ *	base = of_io_request_and_map(node, 0, "foo");
+ *	if (IS_ERR(base))
+ *		return PTR_ERR(base);
+ */
+void __iomem *of_io_request_and_map(struct device_node *np, int index,
+					char *name)
+{
+	struct resource res;
+	void __iomem *mem;
+
+	if (of_address_to_resource(np, index, &res))
+		return IOMEM_ERR_PTR(-EINVAL);
+
+	if (!request_mem_region(res.start, resource_size(&res), name))
+		return IOMEM_ERR_PTR(-EBUSY);
+
+	mem = ioremap(res.start, resource_size(&res));
+	if (!mem) {
+		release_mem_region(res.start, resource_size(&res));
+		return IOMEM_ERR_PTR(-ENOMEM);
+	}
+
+	return mem;
+}
+EXPORT_SYMBOL(of_io_request_and_map);
+
 /**
  * of_dma_get_range - Get DMA range info
  * @np:		device node to get DMA range info

include/linux/io.h

···
 }
 #endif
 
+#define IOMEM_ERR_PTR(err) (__force void __iomem *)ERR_PTR(err)
+
 void __iomem *devm_ioremap(struct device *dev, resource_size_t offset,
 			    unsigned long size);
 void __iomem *devm_ioremap_nocache(struct device *dev, resource_size_t offset,

include/linux/of_address.h

···
 extern int of_address_to_resource(struct device_node *dev, int index,
 				  struct resource *r);
 void __iomem *of_iomap(struct device_node *node, int index);
+void __iomem *of_io_request_and_map(struct device_node *device,
+					int index, char *name);
 #else
+
+#include <linux/io.h>
+
 static inline int of_address_to_resource(struct device_node *dev, int index,
 					 struct resource *r)
 {
···
 static inline void __iomem *of_iomap(struct device_node *device, int index)
 {
 	return NULL;
+}
+
+static inline void __iomem *of_io_request_and_map(struct device_node *device,
+					int index, char *name)
+{
+	return IOMEM_ERR_PTR(-EINVAL);
 }
 #endif
 

lib/devres.c

···
 }
 EXPORT_SYMBOL(devm_iounmap);
 
-#define IOMEM_ERR_PTR(err) (__force void __iomem *)ERR_PTR(err)
-
 /**
  * devm_ioremap_resource() - check, request region, and ioremap resource
  * @dev: generic device to handle the resource for