of_alias_max_index will return the maximum number for which an
alias of a given stem exists. This is useful for frameworks
whishing to reserve a number of device slots from dynamic
allocation.
Signed-off-by: Sascha Hauer <s.ha...@pengutronix.de>
---
drivers/of/base.c | 29 +++++++++++++++++++++++++++++
include/linux/of.h | 6 ++++++
2 files changed, 35 insertions(+)
diff --git a/drivers/of/base.c b/drivers/of/base.c
index f807d0e..f953b9d 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1758,6 +1758,35 @@ static void of_alias_add(struct alias_prop *ap, struct
device_node *np,
ap->alias, ap->stem, ap->id, of_node_full_name(np));
}
+/*
+ * of_alias_max_index() - get the maximum index for a given alias stem
+ * @stem: The alias stem for which the maximum index is searched for
+ *
+ * Given an alias stem (the alias without the number) this function
+ * returns the maximum number for which an alias exists.
+ *
+ * Return: The maximum existing alias index or -ENODEV if no alias
+ * exists for this stem.
+ */
+int of_alias_max_index(const char *stem)
+{
+ struct alias_prop *app;
+ int max = -ENODEV;
+
+ mutex_lock(&of_aliases_mutex);
+
+ list_for_each_entry(app, &aliases_lookup, link) {
+ if (strcmp(app->stem, stem))
+ continue;
+ if (app->id > max)
+ max = app->id;
+ }
+
+ mutex_unlock(&of_aliases_mutex);
+
+ return max;
+}
+
/**
* of_alias_scan - Scan all properties of 'aliases' node
*
diff --git a/include/linux/of.h b/include/linux/of.h
index 276c546..963e295 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -305,6 +305,7 @@ extern int of_count_phandle_with_args(const struct
device_node *np,
extern void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align));
extern int of_alias_get_id(struct device_node *np, const char *stem);
+extern int of_alias_max_index(const char *stem);
extern int of_machine_is_compatible(const char *compat);
@@ -532,6 +533,11 @@ static inline int of_alias_get_id(struct device_node *np,
const char *stem)
return -ENOSYS;
}
+static inline int of_alias_max_index(const char *stem)
+{
+ return -ENODEV;
+}
+
static inline int of_machine_is_compatible(const char *compat)
{
return 0;
--
2.0.0.rc0
--
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