devres: Add devm_of_iomap()

There are still quite a few cases where a device might want
to get to a different node of the device-tree, obtain the
resources and map them.

We have of_iomap() and of_io_request_and_map() but they both
have shortcomings, such as not returning the size of the
resource found (which can be useful) and not being "managed".

This adds a devm_of_iomap() that provides all of these and
should probably replace uses of the above in most drivers.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Joel Stanley <joel@jms.id.au>

2 files changed, 40 insertions, 0 deletions

diff --git a/include/linux/device.h b/include/linux/device.h
index 055a69dbcd18..6aa8d51eabe9 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -696,6 +696,10 @@ extern void devm_free_pages(struct device *dev, unsigned long addr);
 
 void __iomem *devm_ioremap_resource(struct device *dev, struct resource *res);
 
+void __iomem *devm_of_iomap(struct device *dev,
+                            struct device_node *node, int index,
+                            resource_size_t *size);
+
 /* allows to add/remove a custom action to devres stack */
 int devm_add_action(struct device *dev, void (*action)(void *), void *data);
 void devm_remove_action(struct device *dev, void (*action)(void *), void *data);
diff --git a/lib/devres.c b/lib/devres.c
index 5bec1120b392..faccf1a037d0 100644
--- a/lib/devres.c
+++ b/lib/devres.c
@@ -4,6 +4,7 @@
 #include <linux/io.h>
 #include <linux/gfp.h>
 #include <linux/export.h>
+#include <linux/of_address.h>
 
 enum devm_ioremap_type {
         DEVM_IOREMAP = 0,
@@ -162,6 +163,41 @@ void __iomem *devm_ioremap_resource(struct device *dev, struct resource *res)
 }
 EXPORT_SYMBOL(devm_ioremap_resource);
 
+/*
+ * devm_of_iomap - Requests a resource and maps the memory mapped IO
+ *                 for a given device_node managed by a given device
+ *
+ * Checks that a resource is a valid memory region, requests the memory
+ * region and ioremaps it. All operations are managed and will be undone
+ * on driver detach of the device.
+ *
+ * This is to be used when a device requests/maps resources described
+ * by other device tree nodes (children or otherwise).
+ *
+ * @dev:        The device "managing" the resource
+ * @node:       The device-tree node where the resource resides
+ * @index:      index of the MMIO range in the "reg" property
+ * @size:       Returns the size of the resource (pass NULL if not needed)
+ * Returns a pointer to the requested and mapped memory or an ERR_PTR() encoded
+ * error code on failure. Usage example:
+ *
+ *      base = devm_of_iomap(&pdev->dev, node, 0, NULL);
+ *      if (IS_ERR(base))
+ *              return PTR_ERR(base);
+ */
+void __iomem *devm_of_iomap(struct device *dev, struct device_node *node, int index,
+                            resource_size_t *size)
+{
+        struct resource res;
+
+        if (of_address_to_resource(node, index, &res))
+                return IOMEM_ERR_PTR(-EINVAL);
+        if (size)
+                *size = resource_size(&res);
+        return devm_ioremap_resource(dev, &res);
+}
+EXPORT_SYMBOL(devm_of_iomap);
+
 #ifdef CONFIG_HAS_IOPORT_MAP
 /*
  * Generic iomap devres