of: introduce of_parse_phandle_with_fixed_args

This is identical to of_parse_phandle_with_args(), except that the
number of argument cells is fixed, rather than being parsed out of the
node referenced by each phandle.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Grant Likely <grant.likely@linaro.org>

2 files changed, 68 insertions, 8 deletions

diff --git a/drivers/of/base.c b/drivers/of/base.c
index ef2f1d0dd80a..1f80acf4c16a 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1082,7 +1082,8 @@ EXPORT_SYMBOL_GPL(of_property_count_strings);
 
 static int __of_parse_phandle_with_args(const struct device_node *np,
                                         const char *list_name,
-                                        const char *cells_name, int index,
+                                        const char *cells_name,
+                                        int cell_count, int index,
                                         struct of_phandle_args *out_args)
 {
         const __be32 *list, *list_end;
@@ -1118,11 +1119,17 @@ static int __of_parse_phandle_with_args(const struct device_node *np,
                                          np->full_name);
                                 goto err;
                         }
-                        if (of_property_read_u32(node, cells_name, &count)) {
-                                pr_err("%s: could not get %s for %s\n",
-                                         np->full_name, cells_name,
-                                         node->full_name);
-                                goto err;
+
+                        if (cells_name) {
+                                if (of_property_read_u32(node, cells_name,
+                                                         &count)) {
+                                        pr_err("%s: could not get %s for %s\n",
+                                                np->full_name, cells_name,
+                                                node->full_name);
+                                        goto err;
+                                }
+                        } else {
+                                count = cell_count;
                         }
 
                         /*
@@ -1244,11 +1251,53 @@ int of_parse_phandle_with_args(const struct device_node *np, const char *list_na
 {
         if (index < 0)
                 return -EINVAL;
-        return __of_parse_phandle_with_args(np, list_name, cells_name, index, out_args);
+        return __of_parse_phandle_with_args(np, list_name, cells_name, 0,
+                                            index, out_args);
 }
 EXPORT_SYMBOL(of_parse_phandle_with_args);
 
 /**
+ * of_parse_phandle_with_fixed_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
+ * @cell_count: number of argument cells following the phandle
+ * @index:      index of a phandle to parse out
+ * @out_args:   optional pointer to output arguments structure (will be filled)
+ *
+ * This function is useful to parse lists of phandles and their arguments.
+ * Returns 0 on success and fills out_args, on error returns appropriate
+ * errno value.
+ *
+ * Caller is responsible to call of_node_put() on the returned out_args->node
+ * pointer.
+ *
+ * Example:
+ *
+ * phandle1: node1 {
+ * }
+ *
+ * phandle2: node2 {
+ * }
+ *
+ * node3 {
+ *      list = <&phandle1 0 2 &phandle2 2 3>;
+ * }
+ *
+ * To get a device_node of the `node2' node you may call this:
+ * of_parse_phandle_with_fixed_args(node3, "list", 2, 1, &args);
+ */
+int of_parse_phandle_with_fixed_args(const struct device_node *np,
+                                const char *list_name, int cell_count,
+                                int index, struct of_phandle_args *out_args)
+{
+        if (index < 0)
+                return -EINVAL;
+        return __of_parse_phandle_with_args(np, list_name, NULL, cell_count,
+                                           index, out_args);
+}
+EXPORT_SYMBOL(of_parse_phandle_with_fixed_args);
+
+/**
  * of_count_phandle_with_args() - Find the number of phandles references in a property
  * @np:         pointer to a device tree node containing a list
  * @list_name:  property name that contains a list
@@ -1266,7 +1315,8 @@ EXPORT_SYMBOL(of_parse_phandle_with_args);
 int of_count_phandle_with_args(const struct device_node *np, const char *list_name,
                                 const char *cells_name)
 {
-        return __of_parse_phandle_with_args(np, list_name, cells_name, -1, NULL);
+        return __of_parse_phandle_with_args(np, list_name, cells_name, 0, -1,
+                                            NULL);
 }
 EXPORT_SYMBOL(of_count_phandle_with_args);
 
diff --git a/include/linux/of.h b/include/linux/of.h
index 90a8811e9e48..87d08306fef4 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -280,6 +280,9 @@ extern struct device_node *of_parse_phandle(const struct device_node *np,
 extern int of_parse_phandle_with_args(const struct device_node *np,
         const char *list_name, const char *cells_name, int index,
         struct of_phandle_args *out_args);
+extern int of_parse_phandle_with_fixed_args(const struct device_node *np,
+        const char *list_name, int cells_count, int index,
+        struct of_phandle_args *out_args);
 extern int of_count_phandle_with_args(const struct device_node *np,
         const char *list_name, const char *cells_name);
 
@@ -477,6 +480,13 @@ static inline int of_parse_phandle_with_args(struct device_node *np,
         return -ENOSYS;
 }
 
+static inline int of_parse_phandle_with_fixed_args(const struct device_node *np,
+        const char *list_name, int cells_count, int index,
+        struct of_phandle_args *out_args)
+{
+        return -ENOSYS;
+}
+
 static inline int of_count_phandle_with_args(struct device_node *np,
                                              const char *list_name,
                                              const char *cells_name)