3 files changed, 72 insertions, 0 deletions

diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index 1a02b7537c8b..d141b80479b5 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -75,6 +75,9 @@ struct regmap {
 	const void *reg_defaults_raw;
 	void *cache;
 	bool cache_dirty;
+
+	struct reg_default *patch;
+	int patch_regs;
 };
 
 struct regcache_ops {
diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index d1daa5e9fadf..5cd2a37e7688 100644
--- a/drivers/base/regmap/regcache.c
+++ b/drivers/base/regmap/regcache.c
@@ -268,6 +268,17 @@ int regcache_sync(struct regmap *map)
 		map->cache_ops->name);
 	name = map->cache_ops->name;
 	trace_regcache_sync(map->dev, name, "start");
+
+	/* Apply any patch first */
+	for (i = 0; i < map->patch_regs; i++) {
+		ret = _regmap_write(map, map->patch[i].reg, map->patch[i].def);
+		if (ret != 0) {
+			dev_err(map->dev, "Failed to write %x = %x: %d\n",
+				map->patch[i].reg, map->patch[i].def, ret);
+			goto out;
+		}
+	}
+
 	if (!map->cache_dirty)
 		goto out;
 	if (map->cache_ops->sync) {
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index e09119684c06..7ac234f0b1c5 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -673,6 +673,64 @@ int regmap_update_bits_check(struct regmap *map, unsigned int reg,
 EXPORT_SYMBOL_GPL(regmap_update_bits_check);
 
 /**
+ * regmap_register_patch: Register and apply register updates to be applied
+ *                        on device initialistion
+ *
+ * @map: Register map to apply updates to.
+ * @regs: Values to update.
+ * @num_regs: Number of entries in regs.
+ *
+ * Register a set of register updates to be applied to the device
+ * whenever the device registers are synchronised with the cache and
+ * apply them immediately.  Typically this is used to apply
+ * corrections to be applied to the device defaults on startup, such
+ * as the updates some vendors provide to undocumented registers.
+ */
+int regmap_register_patch(struct regmap *map, const struct reg_default *regs,
+			  int num_regs)
+{
+	int i, ret;
+	bool bypass;
+
+	/* If needed the implementation can be extended to support this */
+	if (map->patch)
+		return -EBUSY;
+
+	mutex_lock(&map->lock);
+
+	bypass = map->cache_bypass;
+
+	map->cache_bypass = true;
+
+	/* Write out first; it's useful to apply even if we fail later. */
+	for (i = 0; i < num_regs; i++) {
+		ret = _regmap_write(map, regs[i].reg, regs[i].def);
+		if (ret != 0) {
+			dev_err(map->dev, "Failed to write %x = %x: %d\n",
+				regs[i].reg, regs[i].def, ret);
+			goto out;
+		}
+	}
+
+	map->patch = kcalloc(sizeof(struct reg_default), num_regs, GFP_KERNEL);
+	if (map->patch != NULL) {
+		memcpy(map->patch, regs,
+		       num_regs * sizeof(struct reg_default));
+		map->patch_regs = num_regs;
+	} else {
+		ret = -ENOMEM;
+	}
+
+out:
+	map->cache_bypass = bypass;
+
+	mutex_unlock(&map->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(regmap_register_patch);
+
+/*
  * regmap_get_val_bytes(): Report the size of a register value
  *
  * Report the size of a register value, mainly intended to for use by