[PATCH] [POWERPC] of: add alias helper functions.
From: Grant Likely <hidden>
Date: 2008-02-04 16:17:46
From: Grant Likely <redacted> Add helper functions for translating back and forth between alias properties and device tree nodes. Signed-off-by: Grant Likely <redacted> --- 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 */