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>

1 files changed, 16 insertions, 6 deletions

diff --git a/drivers/of/base.c b/drivers/of/base.c
index cf04d4dd4a5..cd17092b82b 100644
--- 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: