Sometimes it is useful to group similar DT nodes under a common parent,
when a different node can reference the group, meaning, that any subnode
will do the job. An example of such a group is a DMA multiplexer, when a
DMA slave can be served by any DMA controller from the group. This patch
slightly extends an internal __of_parse_phandle_with_args() function to
accept one more optional parameter and exports a new API function
of_parse_phandle_with_child_args(), which allows the caller to provide a
compatibility string for a group. In this case the function returns the
first matching node. Once a matching node is found, standard DT iterators
can be used to look for further matches.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+rene...@gmail.com>
---
drivers/of/base.c | 28 +++++++++++++++++++++++++---
include/linux/of.h | 16 ++++++++++++++++
2 files changed, 41 insertions(+), 3 deletions(-)
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 321d3ef..d114515 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1066,11 +1066,16 @@ EXPORT_SYMBOL(of_parse_phandle);
* @cells_name: property name that specifies phandles' arguments count
* @index: index of a phandle to parse out
* @out_args: optional pointer to output arguments structure (will be filled)
+ * @parent: optional parent-compatibility string
*
* 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.
*
+ * If @parent is specified and the DT node, pointed by the currently iterated
+ * phandle is compatible with it, it is assumed, that the phandle is a parent
of
+ * DT nodes with equal cell counts. In that case the first child is taken.
+ *
* Caller is responsible to call of_node_put() on the returned out_args->node
* pointer.
*
@@ -1094,7 +1099,8 @@ EXPORT_SYMBOL(of_parse_phandle);
static 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)
+ struct of_phandle_args *out_args,
+ const char *parent)
{
const __be32 *list, *list_end;
int rc = 0, size, cur_index = 0;
@@ -1129,6 +1135,12 @@ static int __of_parse_phandle_with_args(const struct
device_node *np,
np->full_name);
goto err;
}
+ if (parent && of_device_is_compatible(node, parent)) {
+ struct device_node *child =
+ of_get_next_available_child(node, NULL);
+ of_node_put(node);
+ node = child;
+ }
if (of_property_read_u32(node, cells_name, &count)) {
pr_err("%s: could not get %s for %s\n",
np->full_name, cells_name,
@@ -1199,10 +1211,20 @@ 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, index,
out_args, NULL);
}
EXPORT_SYMBOL(of_parse_phandle_with_args);
+int of_parse_phandle_with_child_args(const struct device_node *np, const char
*list_name,
+ const char *cells_name, int index,
+ struct of_phandle_args *out_args, const
char *parent)
+{
+ if (index < 0)
+ return -EINVAL;
+ return __of_parse_phandle_with_args(np, list_name, cells_name, index,
out_args, parent);
+}
+EXPORT_SYMBOL(of_parse_phandle_with_child_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
@@ -1221,7 +1243,7 @@ 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, -1,
NULL, NULL);
}
EXPORT_SYMBOL(of_count_phandle_with_args);
diff --git a/include/linux/of.h b/include/linux/of.h
index a0f1292..30ae71f 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -277,6 +277,12 @@ 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_child_args(const struct device_node *np,
+ const char *list_name,
+ const char *cells_name,
+ int index,
+ struct of_phandle_args *out_args,
+ const char *parent);
extern int of_count_phandle_with_args(const struct device_node *np,
const char *list_name, const char *cells_name);
@@ -469,6 +475,16 @@ static inline int of_parse_phandle_with_args(struct
device_node *np,
return -ENOSYS;
}
+static inline int of_parse_phandle_with_child_args(const struct device_node
*np,
+ const char *list_name,
+ const char *cells_name,
+ int index,
+ struct of_phandle_args
*out_args,
+ const char *parent)
+{
+ return -ENOSYS;
+}
+
static inline int of_count_phandle_with_args(struct device_node *np,
const char *list_name,
const char *cells_name)
--
1.7.2.5
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