2 files changed, 48 insertions, 0 deletions

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 3d72cc8e2f3..a12cba32460 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1727,6 +1727,53 @@ out:
 }
 EXPORT_SYMBOL_GPL(regulator_set_voltage);
 
+/**
+ * regulator_sync_voltage - re-apply last regulator output voltage
+ * @regulator: regulator source
+ *
+ * Re-apply the last configured voltage.  This is intended to be used
+ * where some external control source the consumer is cooperating with
+ * has caused the configured voltage to change.
+ */
+int regulator_sync_voltage(struct regulator *regulator)
+{
+        struct regulator_dev *rdev = regulator->rdev;
+        int ret, min_uV, max_uV;
+
+        mutex_lock(&rdev->mutex);
+
+        if (!rdev->desc->ops->set_voltage &&
+            !rdev->desc->ops->set_voltage_sel) {
+                ret = -EINVAL;
+                goto out;
+        }
+
+        /* This is only going to work if we've had a voltage configured. */
+        if (!regulator->min_uV && !regulator->max_uV) {
+                ret = -EINVAL;
+                goto out;
+        }
+
+        min_uV = regulator->min_uV;
+        max_uV = regulator->max_uV;
+
+        /* This should be a paranoia check... */
+        ret = regulator_check_voltage(rdev, &min_uV, &max_uV);
+        if (ret < 0)
+                goto out;
+
+        ret = regulator_check_consumers(rdev, &min_uV, &max_uV);
+        if (ret < 0)
+                goto out;
+
+        ret = _regulator_do_set_voltage(rdev, min_uV, max_uV);
+
+out:
+        mutex_unlock(&rdev->mutex);
+        return ret;
+}
+EXPORT_SYMBOL_GPL(regulator_sync_voltage);
+
 static int _regulator_get_voltage(struct regulator_dev *rdev)
 {
         int sel;
diff --git a/include/linux/regulator/consumer.h b/include/linux/regulator/consumer.h
index ebd74726529..7954f6bd7ed 100644
--- a/include/linux/regulator/consumer.h
+++ b/include/linux/regulator/consumer.h
@@ -154,6 +154,7 @@ int regulator_is_supported_voltage(struct regulator *regulator,
                                    int min_uV, int max_uV);
 int regulator_set_voltage(struct regulator *regulator, int min_uV, int max_uV);
 int regulator_get_voltage(struct regulator *regulator);
+int regulator_sync_voltage(struct regulator *regulator);
 int regulator_set_current_limit(struct regulator *regulator,
                                int min_uA, int max_uA);
 int regulator_get_current_limit(struct regulator *regulator);