of: of_parse_phandles_with_args() learns to differentiate 'hole' cells

Given this list (contains three gpio specifiers, one of which is a hole):

gpios = <&phandle1 1 2 3
         0 /* a hole */
         &phandle2 4 5 6>;

of_parse_phandles_with_args() would report -ENOENT for the `hole'
specifier item, the same error value is used to report the end of the
list, for example.

Sometimes we want to differentiate holes from real errors -- for
example when we want to count all the [syntax correct] specifiers.

With this patch of_parse_phandles_with_args() will report -EEXITS when
somebody requested to parse a hole.

Also, make the out_{node,args} arguments optional, when counting we
don't really need the out values.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

diff --git a/drivers/of/base.c b/drivers/of/base.c
index cf04d4dd4a53c7f41a2969676ed65e9c8a076f09..cd17092b82bd4bbfa93e760e994046861d8f9902 100644 (file)
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -499,8 +499,8 @@ EXPORT_SYMBOL_GPL(of_modalias_node);
  * @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)
+ * @out_node:  optional pointer to device_node struct pointer (will be filled)
+ * @out_args:  optional 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
@@ -534,7 +534,7 @@ int of_parse_phandles_with_args(struct device_node *np, const char *list_name,
        int size;
        int cur_index = 0;
        struct device_node *node = NULL;
-       const void *args;
+       const void *args = NULL;
 
        list = of_get_property(np, list_name, &size);
        if (!list) {
@@ -580,16 +580,26 @@ next:
 
                of_node_put(node);
                node = NULL;
+               args = NULL;
                cur_index++;
        }
 
        if (!node) {
-               ret = -ENOENT;
+               /*
+                * args w/o node indicates that the loop above has stopped at
+                * the 'hole' cell. Report this differently.
+                */
+               if (args)
+                       ret = -EEXIST;
+               else
+                       ret = -ENOENT;
                goto err0;
        }
 
-       *out_node = node;
-       *out_args = args;
+       if (out_node)
+               *out_node = node;
+       if (out_args)
+               *out_args = args;
 
        return 0;
 err1: