[PATCH v2] dt: add of_alias_scan and of_alias_get_id
Grant Likely
grant.likely at secretlab.ca
Fri Jul 15 14:37:27 EDT 2011
From: Shawn Guo <shawn.guo at linaro.org>
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 at linaro.org>
[grant.likey: add locking and rework parse loop]
Signed-off-by: Grant Likely <grant.likely at secretlab.ca>
---
Hi Shawn,
I've reworked as discussed on the ML. Please test and let me know if
it still works for you.
g.
drivers/of/base.c | 130 ++++++++++++++++++++++++++++++++++++++++++++++++
drivers/of/fdt.c | 4 +
include/linux/of.h | 8 +++
include/linux/of_fdt.h | 1
4 files changed, 141 insertions(+), 2 deletions(-)
diff --git a/drivers/of/base.c b/drivers/of/base.c
index b8b65fd..6d9adc6 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.
@@ -980,3 +1005,108 @@ 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;
+ 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 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 the alias backwards to extract the id and work out
+ * the '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 65200af..13d6d3a 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 at 0");
+ of_aliases = of_find_node_by_path("/aliases");
+ of_alias_scan();
}
#endif /* CONFIG_OF_EARLY_FLATTREE */
diff --git a/include/linux/of.h b/include/linux/of.h
index 4fc4c1b..e334c11 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)
@@ -205,6 +206,9 @@ 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(
@@ -217,6 +221,10 @@ 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 void *early_init_dt_alloc_memory_arch(u64 size, u64 align);
+extern void 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);
diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
index c84d900..b74b74f 100644
--- a/include/linux/of_fdt.h
+++ b/include/linux/of_fdt.h
@@ -97,7 +97,6 @@ extern void early_init_dt_check_for_initrd(unsigned long node);
extern int early_init_dt_scan_memory(unsigned long node, const char *uname,
int depth, void *data);
extern void early_init_dt_add_memory_arch(u64 base, u64 size);
-extern void * early_init_dt_alloc_memory_arch(u64 size, u64 align);
extern u64 dt_mem_next_cell(int s, __be32 **cellp);
/*
More information about the linux-arm-kernel
mailing list