From: Grant Likely <[EMAIL PROTECTED]>
Add helper functions for translating back and forth between alias
properties and device tree nodes.
Signed-off-by: Grant Likely <[EMAIL PROTECTED]>
---
drivers/of/base.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/of.h | 2 +
2 files changed, 82 insertions(+), 0 deletions(-)
diff --git a/drivers/of/base.c b/drivers/of/base.c
index b306fef..54a7f2e 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -331,3 +331,83 @@ struct device_node *of_find_matching_node(struct
device_node *from,
return np;
}
EXPORT_SYMBOL(of_find_matching_node);
+
+/**
+ * of_find_node_by_alias - Find a node from an alias name
+ * @alias: Alias to decode
+ *
+ * Returns a node pointer with refcount incremented. Use of_node_put
+ * on it when done.
+ */
+struct device_node *of_find_node_by_alias(const char *alias)
+{
+ struct device_node *np, *alias_np;
+ const char *path;
+
+ np = NULL;
+
+ /* First decode the alias into a path */
+ alias_np = of_find_node_by_path("/aliases");
+ if (!alias_np)
+ return NULL;
+
+ path = of_get_property(alias_np, alias, NULL);
+ if (!path)
+ goto exit;
+
+ /* Next find the node pointed to by the alias */
+ np = of_find_node_by_path(path);
+
+ exit:
+ of_node_put(alias_np);
+ return np;
+}
+
+/**
+ * of_node_alias - Return the alias for a node
+ * @np Pointer to device node
+ * @prefix Prefix string; if provided then this function will only
+ * match on properties which have the given prefix.
+ *
+ * returns the alias property name for the given node without the prefix
+ */
+const char *of_node_alias(struct device_node *np, const char *prefix)
+{
+ struct device_node *alias_np, *test_np;
+ struct property *pp;
+ int prefix_len;
+ const char *alias;
+
+ prefix_len = 0;
+ if (prefix)
+ prefix_len = strlen(prefix);
+
+ /* First decode the alias into a path */
+ alias_np = of_find_node_by_path("/aliases");
+ if (!alias_np)
+ return NULL;
+
+ /* Loop over the aliases looking for a match */
+ alias = NULL;
+ for (pp = alias_np->properties; pp != 0; pp = pp->next) {
+ /* Skip properties which don't begin with the prefix */
+ if (prefix && (strncmp(pp->name, prefix, prefix_len) != 0))
+ continue;
+
+ /* Skip properties which aren't a NULL terminated string */
+ if (memchr(pp->value, 0, pp->length) == NULL)
+ continue;
+
+ /* Find out what node the property points to and see if it
+ * matches. If so then we've found our alias */
+ test_np = of_find_node_by_path(pp->value);
+ if (test_np == np)
+ alias = pp->name + prefix_len;
+ of_node_put(test_np);
+ if (alias)
+ break;
+ }
+
+ of_node_put(alias_np);
+ return alias;
+}
diff --git a/include/linux/of.h b/include/linux/of.h
index b5f33ef..aae1570 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -68,5 +68,7 @@ extern int of_n_addr_cells(struct device_node *np);
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 struct device_node *of_find_node_by_alias(const char *alias);
+extern const char *of_node_alias(struct device_node *np, const char *prefix);
#endif /* _LINUX_OF_H */
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