[PATCH 1/4] regcache: Add support for sorting defaults arrays

[Charles Keepax <ckeepax@xxxxxxxxxxxxxxxxxxxxx>]

The defaults array in regcache must be sorted into ascending register
address order, because binary search is used to locate values in
the array. Add a helper to sort the register defaults array which
can be useful for systems that dynamically create a defaults array
based on external information.

Signed-off-by: Charles Keepax <ckeepax@xxxxxxxxxxxxxxxxxxxxx>
---
 drivers/base/regmap/regcache.c | 31 +++++++++++++++++++++++++++++++
 include/linux/regmap.h         |  7 +++++++
 2 files changed, 38 insertions(+)

diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index b1f8508c3966..f7fcf2de1301 100644
--- a/drivers/base/regmap/regcache.c
+++ b/drivers/base/regmap/regcache.c
@@ -21,6 +21,37 @@ static const struct regcache_ops *cache_types[] = {
 	&regcache_flat_ops,
 };
 
+static int regcache_defaults_cmp(const void *a, const void *b)
+{
+	const struct reg_default *x = a;
+	const struct reg_default *y = b;
+
+	if (x->reg > y->reg)
+		return 1;
+	else if (x->reg < y->reg)
+		return -1;
+	else
+		return 0;
+}
+
+static void regcache_defaults_swap(void *a, void *b, int size)
+{
+	struct reg_default *x = a;
+	struct reg_default *y = b;
+	struct reg_default tmp;
+
+	tmp = *x;
+	*x = *y;
+	*y = tmp;
+}
+
+void regcache_sort_defaults(struct reg_default *defaults, unsigned int ndefaults)
+{
+	sort(defaults, ndefaults, sizeof(*defaults),
+	     regcache_defaults_cmp, regcache_defaults_swap);
+}
+EXPORT_SYMBOL_GPL(regcache_sort_defaults);
+
 static int regcache_hw_init(struct regmap *map)
 {
 	int i, j;
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index 3a96d068915f..d17c5ea3d55d 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -1352,6 +1352,7 @@ bool regmap_can_raw_write(struct regmap *map);
 size_t regmap_get_raw_read_max(struct regmap *map);
 size_t regmap_get_raw_write_max(struct regmap *map);
 
+void regcache_sort_defaults(struct reg_default *defaults, unsigned int ndefaults);
 int regcache_sync(struct regmap *map);
 int regcache_sync_region(struct regmap *map, unsigned int min,
 			 unsigned int max);
@@ -2043,6 +2044,12 @@ static inline bool regmap_might_sleep(struct regmap *map)
 	return true;
 }
 
+static inline void regcache_sort_defaults(struct reg_default *defaults,
+					  unsigned int ndefaults)
+{
+	WARN_ONCE(1, "regmap API is disabled");
+}
+
 static inline int regcache_sync(struct regmap *map)
 {
 	WARN_ONCE(1, "regmap API is disabled");
-- 
2.39.5