regcache: Add support for sorting defaults arrays

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@opensource.cirrus.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.dev>
Link: https://patch.msgid.link/20250217140159.2288784-2-ckeepax@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 31 insertions, 0 deletions

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;