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authorShawn Guo <shawn.guo@linaro.org>2011-08-03 11:28:14 +0100
committerGrant Likely <grant.likely@secretlab.ca>2011-08-03 13:02:31 +0100
commit750f463a749e28464151ad26938d11b07b1c43cb (patch)
tree6aabb1512a4000615e93b25beccba606b62f7237 /drivers/of
parented8f37370d83e695c0a4fa5d5fc7a83ecb947526 (diff)
dt: add of_alias_scan and of_alias_get_id
The patch adds function of_alias_scan to populate a global lookup table with the properties of 'aliases' node and function of_alias_get_id for drivers to find alias id from the lookup table. Signed-off-by: Shawn Guo <shawn.guo@linaro.org> [grant.likely: add locking and rework parse loop] Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Diffstat (limited to 'drivers/of')
-rw-r--r--drivers/of/base.c130
-rw-r--r--drivers/of/fdt.c4
2 files changed, 133 insertions, 1 deletions
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 3ff22e32b602..fb28b5af733b 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -17,14 +17,39 @@
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
+#include <linux/ctype.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/proc_fs.h>
+/**
+ * struct alias_prop - Alias property in 'aliases' node
+ * @link: List node to link the structure in aliases_lookup list
+ * @alias: Alias property name
+ * @np: Pointer to device_node that the alias stands for
+ * @id: Index value from end of alias name
+ * @stem: Alias string without the index
+ *
+ * The structure represents one alias property of 'aliases' node as
+ * an entry in aliases_lookup list.
+ */
+struct alias_prop {
+ struct list_head link;
+ const char *alias;
+ struct device_node *np;
+ int id;
+ char stem[0];
+};
+
+static LIST_HEAD(aliases_lookup);
+
struct device_node *allnodes;
struct device_node *of_chosen;
+struct device_node *of_aliases;
+
+static DEFINE_MUTEX(of_aliases_mutex);
/* use when traversing tree through the allnext, child, sibling,
* or parent members of struct device_node.
@@ -988,3 +1013,108 @@ out_unlock:
}
#endif /* defined(CONFIG_OF_DYNAMIC) */
+static void of_alias_add(struct alias_prop *ap, struct device_node *np,
+ int id, const char *stem, int stem_len)
+{
+ ap->id = id;
+ ap->np = np;
+ strncpy(ap->stem, stem, stem_len);
+ ap->stem[stem_len] = 0;
+ list_add_tail(&ap->link, &aliases_lookup);
+ pr_debug("adding DT alias:%s: stem=%s id=%i node=%s\n",
+ ap->alias, ap->stem, ap->id, np ? np->full_name : NULL);
+}
+
+/**
+ * of_alias_scan() - Scan all properties of 'aliases' node
+ *
+ * The function scans all the properties of 'aliases' node and populate
+ * the global lookup table with the properties. It returns the
+ * number of alias_prop found, or error code in error case.
+ */
+__init void of_alias_scan(void)
+{
+ struct property *pp;
+
+ if (!of_aliases)
+ return;
+
+ for_each_property(pp, of_aliases->properties) {
+ const char *start = pp->name;
+ const char *end = start + strlen(start);
+ struct device_node *np;
+ struct alias_prop *ap;
+ int id, len;
+
+ /* Skip those we do not want to proceed */
+ if (!strcmp(pp->name, "name") ||
+ !strcmp(pp->name, "phandle") ||
+ !strcmp(pp->name, "linux,phandle"))
+ continue;
+
+ np = of_find_node_by_path(pp->value);
+ if (!np)
+ continue;
+
+ /* walk alias backwards to extract the id and 'stem' string */
+ while (isdigit(*(end-1)) && end > start)
+ end--;
+ len = end - start;
+ id = strlen(end) ? simple_strtoul(end, NULL, 10) : -1;
+
+ /* Allocate an alias_prop with enough space for the stem */
+ ap = early_init_dt_alloc_memory_arch(sizeof(*ap) + len + 1, 4);
+ if (!ap)
+ continue;
+ ap->alias = start;
+ of_alias_add(ap, np, id, start, len);
+ }
+}
+
+/**
+ * of_alias_get_id() - Get alias id for the given device_node
+ * @np: Pointer to the given device_node
+ * @stem: Alias stem of the given device_node
+ *
+ * The function travels the lookup table to get alias id for the given
+ * device_node and alias stem. It returns the alias id if find it.
+ * If not, dynamically creates one in the lookup table and returns it,
+ * or returns error code if fail to create.
+ */
+int of_alias_get_id(struct device_node *np, const char *stem)
+{
+ struct alias_prop *app;
+ int id = 0;
+ bool found = false;
+
+ mutex_lock(&of_aliases_mutex);
+ list_for_each_entry(app, &aliases_lookup, link) {
+ if (strcmp(app->stem, stem) != 0)
+ continue;
+
+ if (np == app->np) {
+ found = true;
+ id = app->id;
+ break;
+ }
+
+ if (id <= app->id)
+ id = app->id + 1;
+ }
+
+ /* If an id is not found, then allocate a new one */
+ if (!found) {
+ app = kzalloc(sizeof(*app) + strlen(stem) + 1, 4);
+ if (!app) {
+ id = -ENODEV;
+ goto out;
+ }
+ of_alias_add(app, np, id, stem, strlen(stem));
+ }
+
+ out:
+ mutex_unlock(&of_aliases_mutex);
+
+ return id;
+}
+EXPORT_SYMBOL_GPL(of_alias_get_id);
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 65200af29c52..13d6d3a96b31 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -707,10 +707,12 @@ void __init unflatten_device_tree(void)
__unflatten_device_tree(initial_boot_params, &allnodes,
early_init_dt_alloc_memory_arch);
- /* Get pointer to OF "/chosen" node for use everywhere */
+ /* Get pointer to "/chosen" and "/aliasas" nodes for use everywhere */
of_chosen = of_find_node_by_path("/chosen");
if (of_chosen == NULL)
of_chosen = of_find_node_by_path("/chosen@0");
+ of_aliases = of_find_node_by_path("/aliases");
+ of_alias_scan();
}
#endif /* CONFIG_OF_EARLY_FLATTREE */

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