of: reserved-memory: Support lookup of regions by name

Add support for looking up memory regions by name. This looks up the
given name in the newly introduced memory-region-names property and
returns the memory region at the corresponding index in the memory-
region(s) property.
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/of/of_reserved_mem.c

@@ -357,6 +357,25 @@ int of_reserved_mem_device_init_by_idx(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(of_reserved_mem_device_init_by_idx);
 
+/**
+ * of_reserved_mem_device_init_by_name() - assign named reserved memory region
+ *					   to given device
+ * @dev: pointer to the device to configure
+ * @np: pointer to the device node with 'memory-region' property
+ * @name: name of the selected memory region
+ *
+ * Returns: 0 on success or a negative error-code on failure.
+ */
+int of_reserved_mem_device_init_by_name(struct device *dev,
+					struct device_node *np,
+					const char *name)
+{
+	int idx = of_property_match_string(np, "memory-region-names", name);
+
+	return of_reserved_mem_device_init_by_idx(dev, np, idx);
+}
+EXPORT_SYMBOL_GPL(of_reserved_mem_device_init_by_name);
+
 /**
  * of_reserved_mem_device_release() - release reserved memory device structures
  * @dev:	Pointer to the device to deconfigure

include/linux/of_reserved_mem.h

@@ -33,6 +33,9 @@ typedef int (*reservedmem_of_init_fn)(struct reserved_mem *rmem);
 
 int of_reserved_mem_device_init_by_idx(struct device *dev,
 				       struct device_node *np, int idx);
+int of_reserved_mem_device_init_by_name(struct device *dev,
+					struct device_node *np,
+					const char *name);
 void of_reserved_mem_device_release(struct device *dev);
 
 void fdt_init_reserved_mem(void);
@@ -45,6 +48,14 @@ static inline int of_reserved_mem_device_init_by_idx(struct device *dev,
 {
 	return -ENOSYS;
 }
+
+static inline int of_reserved_mem_device_init_by_name(struct device *dev,
+						      struct device_node *np,
+						      const char *name)
+{
+	return -ENOSYS;
+}
+
 static inline void of_reserved_mem_device_release(struct device *pdev) { }
 
 static inline void fdt_init_reserved_mem(void) { }