regcache: Add ->populate() callback to separate from ->init()

In the future changes we would like to change the flow of the cache handling.
Add ->populate() callback in order to prepare for that.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://patch.msgid.link/20251031080540.3970776-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: andy-shev

drivers/base/regmap/internal.h

@@ -186,6 +186,7 @@ struct regcache_ops {
 	enum regcache_type type;
 	int (*init)(struct regmap *map);
 	int (*exit)(struct regmap *map);
+	int (*populate)(struct regmap *map);
 #ifdef CONFIG_DEBUG_FS
 	void (*debugfs_init)(struct regmap *map);
 #endif

drivers/base/regmap/regcache.c

@@ -222,8 +222,24 @@ int regcache_init(struct regmap *map, const struct regmap_config *config)
 		if (ret)
 			goto err_free;
 	}
+
+	if (map->num_reg_defaults && map->cache_ops->populate) {
+		dev_dbg(map->dev, "Populating %s cache\n", map->cache_ops->name);
+		map->lock(map->lock_arg);
+		ret = map->cache_ops->populate(map);
+		map->unlock(map->lock_arg);
+		if (ret)
+			goto err_exit;
+	}
 	return 0;
 
+err_exit:
+	if (map->cache_ops->exit) {
+		dev_dbg(map->dev, "Destroying %s cache\n", map->cache_ops->name);
+		map->lock(map->lock_arg);
+		ret = map->cache_ops->exit(map);
+		map->unlock(map->lock_arg);
+	}
 err_free:
 	kfree(map->reg_defaults);
 	if (map->cache_free)