1 files changed, 42 insertions, 4 deletions

diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index 4bfa219ef37d..e69102696533 100644
--- a/drivers/base/regmap/regcache.c
+++ b/drivers/base/regmap/regcache.c
@@ -250,6 +250,38 @@ int regcache_write(struct regmap *map,
         return 0;
 }
 
+static int regcache_default_sync(struct regmap *map, unsigned int min,
+                                 unsigned int max)
+{
+        unsigned int reg;
+
+        for (reg = min; reg <= max; reg++) {
+                unsigned int val;
+                int ret;
+
+                if (regmap_volatile(map, reg))
+                        continue;
+
+                ret = regcache_read(map, reg, &val);
+                if (ret)
+                        return ret;
+
+                /* Is this the hardware default?  If so skip. */
+                ret = regcache_lookup_reg(map, reg);
+                if (ret >= 0 && val == map->reg_defaults[ret].def)
+                        continue;
+
+                map->cache_bypass = 1;
+                ret = _regmap_write(map, reg, val);
+                map->cache_bypass = 0;
+                if (ret)
+                        return ret;
+                dev_dbg(map->dev, "Synced register %#x, value %#x\n", reg, val);
+        }
+
+        return 0;
+}
+
 /**
  * regcache_sync: Sync the register cache with the hardware.
  *
@@ -268,7 +300,7 @@ int regcache_sync(struct regmap *map)
         const char *name;
         unsigned int bypass;
 
-        BUG_ON(!map->cache_ops || !map->cache_ops->sync);
+        BUG_ON(!map->cache_ops);
 
         map->lock(map->lock_arg);
         /* Remember the initial bypass state */
@@ -297,7 +329,10 @@ int regcache_sync(struct regmap *map)
         }
         map->cache_bypass = 0;
 
-        ret = map->cache_ops->sync(map, 0, map->max_register);
+        if (map->cache_ops->sync)
+                ret = map->cache_ops->sync(map, 0, map->max_register);
+        else
+                ret = regcache_default_sync(map, 0, map->max_register);
 
         if (ret == 0)
                 map->cache_dirty = false;
@@ -331,7 +366,7 @@ int regcache_sync_region(struct regmap *map, unsigned int min,
         const char *name;
         unsigned int bypass;
 
-        BUG_ON(!map->cache_ops || !map->cache_ops->sync);
+        BUG_ON(!map->cache_ops);
 
         map->lock(map->lock_arg);
 
@@ -346,7 +381,10 @@ int regcache_sync_region(struct regmap *map, unsigned int min,
         if (!map->cache_dirty)
                 goto out;
 
-        ret = map->cache_ops->sync(map, min, max);
+        if (map->cache_ops->sync)
+                ret = map->cache_ops->sync(map, min, max);
+        else
+                ret = regcache_default_sync(map, min, max);
 
 out:
         trace_regcache_sync(map->dev, name, "stop region");