device property: Introduce fwnode_get_id()

Using fwnode_get_id(), get the reg property value for DT node
and get the _ADR object value for ACPI node.

Signed-off-by: Calvin Johnson <calvin.johnson@oss.nxp.com>

drivers/base/property.c

@@ -580,6 +580,32 @@ const char *fwnode_get_name_prefix(const struct fwnode_handle *fwnode)
 	return fwnode_call_ptr_op(fwnode, get_name_prefix);
 }
 
+/**
+ * fwnode_get_id - Get the id of a fwnode.
+ * @fwnode: firmware node
+ * @id: id of the fwnode
+ *
+ * Returns 0 on success or a negative errno.
+ */
+int fwnode_get_id(struct fwnode_handle *fwnode, u32 *id)
+{
+	unsigned long long adr;
+	acpi_status status;
+
+	if (is_of_node(fwnode)) {
+		return of_property_read_u32(to_of_node(fwnode), "reg", id);
+	} else if (is_acpi_node(fwnode)) {
+		status = acpi_evaluate_integer(ACPI_HANDLE_FWNODE(fwnode),
+					       METHOD_NAME__ADR, NULL, &adr);
+		if (ACPI_FAILURE(status))
+			return -ENODATA;
+		*id = (u32)adr;
+		return 0;
+	}
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(fwnode_get_id);
+
 /**
  * fwnode_get_parent - Return parent firwmare node
  * @fwnode: Firmware whose parent is retrieved

include/linux/property.h

@@ -82,6 +82,7 @@ struct fwnode_handle *fwnode_find_reference(const struct fwnode_handle *fwnode,
 
 const char *fwnode_get_name(const struct fwnode_handle *fwnode);
 const char *fwnode_get_name_prefix(const struct fwnode_handle *fwnode);
+int fwnode_get_id(struct fwnode_handle *fwnode, u32 *id);
 struct fwnode_handle *fwnode_get_parent(const struct fwnode_handle *fwnode);
 struct fwnode_handle *fwnode_get_next_parent(
 	struct fwnode_handle *fwnode);