of: Add new helper of_parse_phandles_with_args()
The helper is factored out of of_get_gpio(). Will be used by the QE
pin multiplexing functions (they need to parse the gpios = <> too).
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/drivers/of/base.c b/drivers/of/base.c
index cd1ce7a..4270eb4 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -458,3 +458,112 @@
}
EXPORT_SYMBOL_GPL(of_modalias_node);
+/**
+ * of_parse_phandles_with_args - Find a node pointed by phandle in a list
+ * @np: pointer to a device tree node containing a list
+ * @list_name: property name that contains a list
+ * @cells_name: property name that specifies phandles' arguments count
+ * @index: index of a phandle to parse out
+ * @out_node: pointer to device_node struct pointer (will be filled)
+ * @out_args: pointer to arguments pointer (will be filled)
+ *
+ * This function is useful to parse lists of phandles and their arguments.
+ * Returns 0 on success and fills out_node and out_args, on error returns
+ * appropriate errno value.
+ *
+ * Example:
+ *
+ * phandle1: node1 {
+ * #list-cells = <2>;
+ * }
+ *
+ * phandle2: node2 {
+ * #list-cells = <1>;
+ * }
+ *
+ * node3 {
+ * list = <&phandle1 1 2 &phandle2 3>;
+ * }
+ *
+ * To get a device_node of the `node2' node you may call this:
+ * of_parse_phandles_with_args(node3, "list", "#list-cells", 2, &node2, &args);
+ */
+int of_parse_phandles_with_args(struct device_node *np, const char *list_name,
+ const char *cells_name, int index,
+ struct device_node **out_node,
+ const void **out_args)
+{
+ int ret = -EINVAL;
+ const u32 *list;
+ const u32 *list_end;
+ int size;
+ int cur_index = 0;
+ struct device_node *node = NULL;
+ const void *args;
+
+ list = of_get_property(np, list_name, &size);
+ if (!list) {
+ ret = -ENOENT;
+ goto err0;
+ }
+ list_end = list + size / sizeof(*list);
+
+ while (list < list_end) {
+ const u32 *cells;
+ const phandle *phandle;
+
+ phandle = list;
+ args = list + 1;
+
+ /* one cell hole in the list = <>; */
+ if (!*phandle) {
+ list++;
+ goto next;
+ }
+
+ node = of_find_node_by_phandle(*phandle);
+ if (!node) {
+ pr_debug("%s: could not find phandle\n",
+ np->full_name);
+ goto err0;
+ }
+
+ cells = of_get_property(node, cells_name, &size);
+ if (!cells || size != sizeof(*cells)) {
+ pr_debug("%s: could not get %s for %s\n",
+ np->full_name, cells_name, node->full_name);
+ goto err1;
+ }
+
+ /* Next phandle is at offset of one phandle cell + #cells */
+ list += 1 + *cells;
+ if (list > list_end) {
+ pr_debug("%s: insufficient arguments length\n",
+ np->full_name);
+ goto err1;
+ }
+next:
+ if (cur_index == index)
+ break;
+
+ of_node_put(node);
+ node = NULL;
+ cur_index++;
+ }
+
+ if (!node) {
+ ret = -ENOENT;
+ goto err0;
+ }
+
+ *out_node = node;
+ *out_args = args;
+
+ return 0;
+err1:
+ of_node_put(node);
+err0:
+ pr_debug("%s failed with status %d\n", __func__, ret);
+ return ret;
+}
+EXPORT_SYMBOL(of_parse_phandles_with_args);