[PATCH 1/2 v2] OF: new helper: of_parse_phandles_with_args()
Anton Vorontsov
avorontsov at ru.mvista.com
Sat Oct 11 01:43:17 EST 2008
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 at ru.mvista.com>
---
On Fri, Oct 10, 2008 at 02:37:29PM +1100, Benjamin Herrenschmidt wrote:
[...]
> Rather than incrementing i, I would just use a running pointer "list"
> and drop "i" totally. Not big deal tho.
Done.
> > + /* one cell hole in the list = <>; */
> > + if (!*phandle) {
> > + if (cur_index == index)
> > + return -ENOENT;
> > + i++;
> > + continue;
> > + }
>
> I don't totally understand the above. The 0 phandle terminates the list
> or is just an empty slot in it ?
An empty slot case.
> In the later case, it might be more
> readable to use goto to skip over down to the normal if (cur_index ==
> index) break; and let it return via the normal if (!node) return -ENOENT
> out of the loop.
Agree, done.
> Appart from that it's good and I'm fine with putting it in if you respin
> despite being a bit late mostly because it's me who is later reviewing
> there :-)
Much appreciated. Thanks for the comments.
drivers/of/base.c | 109 ++++++++++++++++++++++++++++++++++++++++++++++++++++
drivers/of/gpio.c | 79 +++++++++-----------------------------
include/linux/of.h | 3 +
3 files changed, 130 insertions(+), 61 deletions(-)
diff --git a/drivers/of/base.c b/drivers/of/base.c
index ad8ac1a..517da97 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -473,3 +473,112 @@ int of_modalias_node(struct device_node *node, char *modalias, int len)
}
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);
diff --git a/drivers/of/gpio.c b/drivers/of/gpio.c
index 1c9cab8..7cd7301 100644
--- a/drivers/of/gpio.c
+++ b/drivers/of/gpio.c
@@ -28,78 +28,35 @@
*/
int of_get_gpio(struct device_node *np, int index)
{
- int ret = -EINVAL;
+ int ret;
struct device_node *gc;
struct of_gpio_chip *of_gc = NULL;
int size;
- const u32 *gpios;
- u32 nr_cells;
- int i;
const void *gpio_spec;
const u32 *gpio_cells;
- int gpio_index = 0;
- gpios = of_get_property(np, "gpios", &size);
- if (!gpios) {
- ret = -ENOENT;
+ ret = of_parse_phandles_with_args(np, "gpios", "#gpio-cells", index,
+ &gc, &gpio_spec);
+ if (ret) {
+ pr_debug("%s: can't parse gpios property\n", __func__);
goto err0;
}
- nr_cells = size / sizeof(u32);
-
- for (i = 0; i < nr_cells; gpio_index++) {
- const phandle *gpio_phandle;
-
- gpio_phandle = gpios + i;
- gpio_spec = gpio_phandle + 1;
-
- /* one cell hole in the gpios = <>; */
- if (!*gpio_phandle) {
- if (gpio_index == index)
- return -ENOENT;
- i++;
- continue;
- }
-
- gc = of_find_node_by_phandle(*gpio_phandle);
- if (!gc) {
- pr_debug("%s: could not find phandle for gpios\n",
- np->full_name);
- goto err0;
- }
-
- of_gc = gc->data;
- if (!of_gc) {
- pr_debug("%s: gpio controller %s isn't registered\n",
- np->full_name, gc->full_name);
- goto err1;
- }
-
- gpio_cells = of_get_property(gc, "#gpio-cells", &size);
- if (!gpio_cells || size != sizeof(*gpio_cells) ||
- *gpio_cells != of_gc->gpio_cells) {
- pr_debug("%s: wrong #gpio-cells for %s\n",
- np->full_name, gc->full_name);
- goto err1;
- }
-
- /* Next phandle is at phandle cells + #gpio-cells */
- i += sizeof(*gpio_phandle) / sizeof(u32) + *gpio_cells;
- if (i >= nr_cells + 1) {
- pr_debug("%s: insufficient gpio-spec length\n",
- np->full_name);
- goto err1;
- }
-
- if (gpio_index == index)
- break;
-
- of_gc = NULL;
- of_node_put(gc);
- }
+ of_gc = gc->data;
if (!of_gc) {
- ret = -ENOENT;
- goto err0;
+ pr_debug("%s: gpio controller %s isn't registered\n",
+ np->full_name, gc->full_name);
+ ret = -ENODEV;
+ goto err1;
+ }
+
+ gpio_cells = of_get_property(gc, "#gpio-cells", &size);
+ if (!gpio_cells || size != sizeof(*gpio_cells) ||
+ *gpio_cells != of_gc->gpio_cells) {
+ pr_debug("%s: wrong #gpio-cells for %s\n",
+ np->full_name, gc->full_name);
+ ret = -EINVAL;
+ goto err1;
}
ret = of_gc->xlate(of_gc, np, gpio_spec);
diff --git a/include/linux/of.h b/include/linux/of.h
index 79886ad..e2488f5 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -71,5 +71,8 @@ extern int of_n_size_cells(struct device_node *np);
extern const struct of_device_id *of_match_node(
const struct of_device_id *matches, const struct device_node *node);
extern int of_modalias_node(struct device_node *node, char *modalias, int len);
+extern 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);
#endif /* _LINUX_OF_H */
--
1.5.6.3
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