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Subject[PATCH v2 1/5] dt: add of_alias_scan and of_alias_get_id
Date
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>
Cc: Grant Likely <grant.likely@secretlab.ca>
---
drivers/of/base.c | 181 ++++++++++++++++++++++++++++++++++++++++++++++++++++
drivers/of/fdt.c | 6 ++
include/linux/of.h | 7 ++
3 files changed, 194 insertions(+), 0 deletions(-)
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 632ebae..89efd10 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -17,14 +17,38 @@
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
+#include <linux/bootmem.h>
+#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
+ * @alias_id: Alias id decoded from alias
+ * @alias_stem: Alias stem name decoded from alias
+ *
+ * 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 alias_id;
+ char alias_stem[0];
+};
+
+static LIST_HEAD(aliases_lookup);
+
struct device_node *allnodes;
struct device_node *of_chosen;
+struct device_node *of_aliases;

/* use when traversing tree through the allnext, child, sibling,
* or parent members of struct device_node.
@@ -922,3 +946,160 @@ out_unlock:
}
#endif /* defined(CONFIG_OF_DYNAMIC) */

+/*
+ * of_alias_find_available_id - Find an available 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 find an available id for the
+ * given device_node with given alias stem. It returns the id found.
+ */
+static int of_alias_find_available_id(struct device_node *np, const char *stem)
+{
+ struct alias_prop *app;
+ int id = 0;
+
+ while (1) {
+ bool used = false;
+ list_for_each_entry(app, &aliases_lookup, link) {
+ if (!strcmp(app->alias_stem, stem) &&
+ app->alias_id == id) {
+ used = true;
+ break;
+ }
+ }
+
+ if (used)
+ id++;
+ else
+ return id;
+ }
+}
+
+/**
+ * of_alias_lookup_add - Add alias into lookup table
+ * @alias: Alias name
+ * @id: Alias id
+ * @stem: Alias stem name
+ * @np: Pointer to device_node
+ *
+ * The function adds one alias into the lookup table and populate it
+ * with the info passed in. It returns 0 in sucess, or error code.
+ */
+static int of_alias_lookup_add(char *alias, int id, const char *stem,
+ struct device_node *np)
+{
+ struct alias_prop *app;
+ size_t sz = sizeof(*app) + strlen(stem) + 1;
+
+ app = kzalloc(sz, GFP_KERNEL);
+ if (!app) {
+ /*
+ * It may fail due to being called by boot code,
+ * so try alloc_bootmem before return error.
+ */
+ app = alloc_bootmem(sz);
+ if (!app)
+ return -ENOMEM;
+ }
+
+ app->np = np;
+ app->alias = alias;
+ app->alias_id = id;
+ strcpy(app->alias_stem, stem);
+ list_add_tail(&app->link, &aliases_lookup);
+
+ return 0;
+}
+
+/**
+ * of_alias_decode - Decode alias stem and id from alias name
+ * @alias: Alias name to be decoded
+ * @stem: Pointer used to return stem name
+ *
+ * The function decodes alias stem name and alias id from the given
+ * alias name. It returns stem name via parameter 'stem', and stem id
+ * via the return value. If no id is found in alias name, it returns 0
+ * as the default.
+ */
+static int of_alias_decode(char *alias, char *stem)
+{
+ int len = strlen(alias);
+ char *end = alias + len;
+
+ while (isdigit(*--end))
+ len--;
+
+ strncpy(stem, alias, len);
+ stem[len] = '\0';
+
+ return strlen(++end) ? simple_strtoul(end, NULL, 10) : 0;
+}
+
+/**
+ * of_alias_scan - Scan all properties of 'aliases' node
+ *
+ * The function scans all the properties of 'aliases' node and populate
+ * the the global lookup table with the properties. It returns the
+ * number of alias_prop found, or error code in error case.
+ */
+int of_alias_scan(void)
+{
+ struct property *pp;
+ int ret, num = 0;
+
+ if (!of_aliases)
+ return -ENODEV;
+
+ for_each_property(pp, of_aliases->properties) {
+ char stem[32];
+ int id = of_alias_decode(pp->name, stem);
+
+ /* Skip those we do not want to proceed */
+ if (!strcmp(pp->name, "name") ||
+ !strcmp(pp->name, "phandle") ||
+ !strcmp(pp->name, "linux,phandle"))
+ continue;
+
+ ret = of_alias_lookup_add(pp->name, id, stem,
+ of_find_node_by_path(pp->value));
+ if (ret < 0)
+ return ret;
+ else
+ num++;
+ }
+
+ return num;
+}
+
+/**
+ * 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 = -1;
+
+ list_for_each_entry(app, &aliases_lookup, link) {
+ if (np == app->np) {
+ id = app->alias_id;
+ break;
+ }
+ }
+
+ if (id == -1) {
+ id = of_alias_find_available_id(np, stem);
+ if (of_alias_lookup_add(NULL, id, stem, np) < 0)
+ return -ENODEV;
+ }
+
+ return id;
+}
+EXPORT_SYMBOL_GPL(of_alias_get_id);
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 65200af..998dc63 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -711,6 +711,12 @@ void __init unflatten_device_tree(void)
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");
+ if (of_aliases == NULL)
+ of_aliases = of_find_node_by_path("/aliases@0");
+
+ of_alias_scan();
}

#endif /* CONFIG_OF_EARLY_FLATTREE */
diff --git a/include/linux/of.h b/include/linux/of.h
index bfc0ed1..c35cc47 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -68,6 +68,7 @@ struct device_node {
/* Pointer for first entry in chain of all nodes. */
extern struct device_node *allnodes;
extern struct device_node *of_chosen;
+extern struct device_node *of_aliases;
extern rwlock_t devtree_lock;

static inline bool of_have_populated_dt(void)
@@ -201,6 +202,9 @@ extern int of_device_is_available(const struct device_node *device);
extern const void *of_get_property(const struct device_node *node,
const char *name,
int *lenp);
+#define for_each_property(pp, properties) \
+ for (pp = properties; pp != NULL; pp = pp->next)
+
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(
@@ -213,6 +217,9 @@ 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);

+extern int of_alias_scan(void);
+extern int of_alias_get_id(struct device_node *np, const char *stem);
+
extern int of_machine_is_compatible(const char *compat);

extern int prom_add_property(struct device_node* np, struct property* prop);
--
1.7.4.1


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