Merge branch 'topic/coupled' of...

Merge branch 'topic/coupled' of https://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator into regulator-4.21 for trivial conflict

Documentation/devicetree/bindings/regulator/regulator.txt

@@ -82,6 +82,8 @@ Optional properties:
 - regulator-coupled-max-spread: Array of maximum spread between voltages of
   coupled regulators in microvolts, each value in the array relates to the
   corresponding couple specified by the regulator-coupled-with property.
+- regulator-max-step-microvolt: Maximum difference between current and target
+  voltages that can be changed safely in a single step.
 
 Deprecated properties:
 - regulator-compatible: If a regulator chip contains multiple

drivers/regulator/core.c

@@ -50,6 +50,8 @@
 #define rdev_dbg(rdev, fmt, ...)					\
 	pr_debug("%s: " fmt, rdev_get_name(rdev), ##__VA_ARGS__)
 
+static DEFINE_WW_CLASS(regulator_ww_class);
+static DEFINE_MUTEX(regulator_nesting_mutex);
 static DEFINE_MUTEX(regulator_list_mutex);
 static LIST_HEAD(regulator_map_list);
 static LIST_HEAD(regulator_ena_gpio_list);
@@ -105,6 +107,11 @@ static int _notifier_call_chain(struct regulator_dev *rdev,
 				  unsigned long event, void *data);
 static int _regulator_do_set_voltage(struct regulator_dev *rdev,
 				     int min_uV, int max_uV);
+static int regulator_balance_voltage(struct regulator_dev *rdev,
+				     suspend_state_t state);
+static int regulator_set_voltage_rdev(struct regulator_dev *rdev,
+				      int min_uV, int max_uV,
+				      suspend_state_t state);
 static struct regulator *create_regulator(struct regulator_dev *rdev,
 					  struct device *dev,
 					  const char *supply_name);
@@ -149,7 +156,7 @@ static inline struct regulator_dev *rdev_get_supply(struct regulator_dev *rdev)
 /**
  * regulator_lock_nested - lock a single regulator
  * @rdev:		regulator source
- * @subclass:		mutex subclass used for lockdep
+ * @ww_ctx:		w/w mutex acquire context
  *
  * This function can be called many times by one task on
  * a single regulator and its mutex will be locked only
@@ -157,24 +164,52 @@ static inline struct regulator_dev *rdev_get_supply(struct regulator_dev *rdev)
  * than the one, which initially locked the mutex, it will
  * wait on mutex.
  */
-static void regulator_lock_nested(struct regulator_dev *rdev,
-				  unsigned int subclass)
+static inline int regulator_lock_nested(struct regulator_dev *rdev,
+					struct ww_acquire_ctx *ww_ctx)
 {
-	if (!mutex_trylock(&rdev->mutex)) {
-		if (rdev->mutex_owner == current) {
+	bool lock = false;
+	int ret = 0;
+
+	mutex_lock(&regulator_nesting_mutex);
+
+	if (ww_ctx || !ww_mutex_trylock(&rdev->mutex)) {
+		if (rdev->mutex_owner == current)
 			rdev->ref_cnt++;
-			return;
+		else
+			lock = true;
+
+		if (lock) {
+			mutex_unlock(&regulator_nesting_mutex);
+			ret = ww_mutex_lock(&rdev->mutex, ww_ctx);
+			mutex_lock(&regulator_nesting_mutex);
 		}
-		mutex_lock_nested(&rdev->mutex, subclass);
+	} else {
+		lock = true;
 	}
 
-	rdev->ref_cnt = 1;
-	rdev->mutex_owner = current;
+	if (lock && ret != -EDEADLK) {
+		rdev->ref_cnt++;
+		rdev->mutex_owner = current;
+	}
+
+	mutex_unlock(&regulator_nesting_mutex);
+
+	return ret;
 }
 
-static inline void regulator_lock(struct regulator_dev *rdev)
+/**
+ * regulator_lock - lock a single regulator
+ * @rdev:		regulator source
+ *
+ * This function can be called many times by one task on
+ * a single regulator and its mutex will be locked only
+ * once. If a task, which is calling this function is other
+ * than the one, which initially locked the mutex, it will
+ * wait on mutex.
+ */
+void regulator_lock(struct regulator_dev *rdev)
 {
-	regulator_lock_nested(rdev, 0);
+	regulator_lock_nested(rdev, NULL);
 }
 
 /**
@@ -184,47 +219,159 @@ static inline void regulator_lock(struct regulator_dev *rdev)
  * This function unlocks the mutex when the
  * reference counter reaches 0.
  */
-static void regulator_unlock(struct regulator_dev *rdev)
+void regulator_unlock(struct regulator_dev *rdev)
+{
+	mutex_lock(&regulator_nesting_mutex);
+
+	if (--rdev->ref_cnt == 0) {
+		rdev->mutex_owner = NULL;
+		ww_mutex_unlock(&rdev->mutex);
+	}
+
+	WARN_ON_ONCE(rdev->ref_cnt < 0);
+
+	mutex_unlock(&regulator_nesting_mutex);
+}
+
+static bool regulator_supply_is_couple(struct regulator_dev *rdev)
 {
-	if (rdev->ref_cnt != 0) {
-		rdev->ref_cnt--;
+	struct regulator_dev *c_rdev;
+	int i;
+
+	for (i = 1; i < rdev->coupling_desc.n_coupled; i++) {
+		c_rdev = rdev->coupling_desc.coupled_rdevs[i];
 
-		if (!rdev->ref_cnt) {
-			rdev->mutex_owner = NULL;
-			mutex_unlock(&rdev->mutex);
+		if (rdev->supply->rdev == c_rdev)
+			return true;
+	}
+
+	return false;
+}
+
+static void regulator_unlock_recursive(struct regulator_dev *rdev,
+				       unsigned int n_coupled)
+{
+	struct regulator_dev *c_rdev;
+	int i;
+
+	for (i = n_coupled; i > 0; i--) {
+		c_rdev = rdev->coupling_desc.coupled_rdevs[i - 1];
+
+		if (!c_rdev)
+			continue;
+
+		if (c_rdev->supply && !regulator_supply_is_couple(c_rdev))
+			regulator_unlock_recursive(
+					c_rdev->supply->rdev,
+					c_rdev->coupling_desc.n_coupled);
+
+		regulator_unlock(c_rdev);
+	}
+}
+
+static int regulator_lock_recursive(struct regulator_dev *rdev,
+				    struct regulator_dev **new_contended_rdev,
+				    struct regulator_dev **old_contended_rdev,
+				    struct ww_acquire_ctx *ww_ctx)
+{
+	struct regulator_dev *c_rdev;
+	int i, err;
+
+	for (i = 0; i < rdev->coupling_desc.n_coupled; i++) {
+		c_rdev = rdev->coupling_desc.coupled_rdevs[i];
+
+		if (!c_rdev)
+			continue;
+
+		if (c_rdev != *old_contended_rdev) {
+			err = regulator_lock_nested(c_rdev, ww_ctx);
+			if (err) {
+				if (err == -EDEADLK) {
+					*new_contended_rdev = c_rdev;
+					goto err_unlock;
+				}
+
+				/* shouldn't happen */
+				WARN_ON_ONCE(err != -EALREADY);
+			}
+		} else {
+			*old_contended_rdev = NULL;
+		}
+
+		if (c_rdev->supply && !regulator_supply_is_couple(c_rdev)) {
+			err = regulator_lock_recursive(c_rdev->supply->rdev,
+						       new_contended_rdev,
+						       old_contended_rdev,
+						       ww_ctx);
+			if (err) {
+				regulator_unlock(c_rdev);
+				goto err_unlock;
+			}
 		}
 	}
+
+	return 0;
+
+err_unlock:
+	regulator_unlock_recursive(rdev, i);
+
+	return err;
 }
 
 /**
- * regulator_lock_supply - lock a regulator and its supplies
- * @rdev:         regulator source
+ * regulator_unlock_dependent - unlock regulator's suppliers and coupled
+ *				regulators
+ * @rdev:			regulator source
+ * @ww_ctx:			w/w mutex acquire context
+ *
+ * Unlock all regulators related with rdev by coupling or suppling.
  */
-static void regulator_lock_supply(struct regulator_dev *rdev)
+static void regulator_unlock_dependent(struct regulator_dev *rdev,
+				       struct ww_acquire_ctx *ww_ctx)
 {
-	int i;
-
-	for (i = 0; rdev; rdev = rdev_get_supply(rdev), i++)
-		regulator_lock_nested(rdev, i);
+	regulator_unlock_recursive(rdev, rdev->coupling_desc.n_coupled);
+	ww_acquire_fini(ww_ctx);
 }
 
 /**
- * regulator_unlock_supply - unlock a regulator and its supplies
- * @rdev:         regulator source
+ * regulator_lock_dependent - lock regulator's suppliers and coupled regulators
+ * @rdev:			regulator source
+ * @ww_ctx:			w/w mutex acquire context
+ *
+ * This function as a wrapper on regulator_lock_recursive(), which locks
+ * all regulators related with rdev by coupling or suppling.
  */
-static void regulator_unlock_supply(struct regulator_dev *rdev)
+static void regulator_lock_dependent(struct regulator_dev *rdev,
+				     struct ww_acquire_ctx *ww_ctx)
 {
-	struct regulator *supply;
+	struct regulator_dev *new_contended_rdev = NULL;
+	struct regulator_dev *old_contended_rdev = NULL;
+	int err;
 
-	while (1) {
-		regulator_unlock(rdev);
-		supply = rdev->supply;
+	mutex_lock(&regulator_list_mutex);
 
-		if (!rdev->supply)
-			return;
+	ww_acquire_init(ww_ctx, &regulator_ww_class);
 
-		rdev = supply->rdev;
-	}
+	do {
+		if (new_contended_rdev) {
+			ww_mutex_lock_slow(&new_contended_rdev->mutex, ww_ctx);
+			old_contended_rdev = new_contended_rdev;
+			old_contended_rdev->ref_cnt++;
+		}
+
+		err = regulator_lock_recursive(rdev,
+					       &new_contended_rdev,
+					       &old_contended_rdev,
+					       ww_ctx);
+
+		if (old_contended_rdev)
+			regulator_unlock(old_contended_rdev);
+
+	} while (err == -EDEADLK);
+
+	ww_acquire_done(ww_ctx);
+
+	mutex_unlock(&regulator_list_mutex);
 }
 
 /**
@@ -773,7 +920,7 @@ static int drms_uA_update(struct regulator_dev *rdev)
 	int current_uA = 0, output_uV, input_uV, err;
 	unsigned int mode;
 
-	lockdep_assert_held_once(&rdev->mutex);
+	lockdep_assert_held_once(&rdev->mutex.base);
 
 	/*
 	 * first check to see if we can set modes at all, otherwise just
@@ -1748,6 +1895,16 @@ struct regulator *_regulator_get(struct device *dev, const char *id,
 		return regulator;
 	}
 
+	mutex_lock(&regulator_list_mutex);
+	ret = (rdev->coupling_desc.n_resolved != rdev->coupling_desc.n_coupled);
+	mutex_unlock(&regulator_list_mutex);
+
+	if (ret != 0) {
+		regulator = ERR_PTR(-EPROBE_DEFER);
+		put_device(&rdev->dev);
+		return regulator;
+	}
+
 	ret = regulator_resolve_supply(rdev);
 	if (ret < 0) {
 		regulator = ERR_PTR(ret);
@@ -2265,7 +2422,20 @@ static int _regulator_enable(struct regulator_dev *rdev)
 {
 	int ret;
 
-	lockdep_assert_held_once(&rdev->mutex);
+	lockdep_assert_held_once(&rdev->mutex.base);
+
+	if (rdev->supply) {
+		ret = _regulator_enable(rdev->supply->rdev);
+		if (ret < 0)
+			return ret;
+	}
+
+	/* balance only if there are regulators coupled */
+	if (rdev->coupling_desc.n_coupled > 1) {
+		ret = regulator_balance_voltage(rdev, PM_SUSPEND_ON);
+		if (ret < 0)
+			goto err_disable_supply;
+	}
 
 	/* check voltage and requested load before enabling */
 	if (regulator_ops_is_valid(rdev, REGULATOR_CHANGE_DRMS))
@@ -2276,18 +2446,20 @@ static int _regulator_enable(struct regulator_dev *rdev)
 		ret = _regulator_is_enabled(rdev);
 		if (ret == -EINVAL || ret == 0) {
 			if (!regulator_ops_is_valid(rdev,
-					REGULATOR_CHANGE_STATUS))
-				return -EPERM;
+					REGULATOR_CHANGE_STATUS)) {
+				ret = -EPERM;
+				goto err_disable_supply;
+			}
 
 			ret = _regulator_do_enable(rdev);
 			if (ret < 0)
-				return ret;
+				goto err_disable_supply;
 
 			_notifier_call_chain(rdev, REGULATOR_EVENT_ENABLE,
 					     NULL);
 		} else if (ret < 0) {
 			rdev_err(rdev, "is_enabled() failed: %d\n", ret);
-			return ret;
+			goto err_disable_supply;
 		}
 		/* Fallthrough on positive return values - already enabled */
 	}
@@ -2295,6 +2467,12 @@ static int _regulator_enable(struct regulator_dev *rdev)
 	rdev->use_count++;
 
 	return 0;
+
+err_disable_supply:
+	if (rdev->supply)
+		_regulator_disable(rdev->supply->rdev);
+
+	return ret;
 }
 
 /**
@@ -2311,23 +2489,15 @@ static int _regulator_enable(struct regulator_dev *rdev)
 int regulator_enable(struct regulator *regulator)
 {
 	struct regulator_dev *rdev = regulator->rdev;
+	struct ww_acquire_ctx ww_ctx;
 	int ret = 0;
 
 	if (regulator->always_on)
 		return 0;
 
-	if (rdev->supply) {
-		ret = regulator_enable(rdev->supply);
-		if (ret != 0)
-			return ret;
-	}
-
-	mutex_lock(&rdev->mutex);
+	regulator_lock_dependent(rdev, &ww_ctx);
 	ret = _regulator_enable(rdev);
-	mutex_unlock(&rdev->mutex);
-
-	if (ret != 0 && rdev->supply)
-		regulator_disable(rdev->supply);
+	regulator_unlock_dependent(rdev, &ww_ctx);
 
 	return ret;
 }
@@ -2369,7 +2539,7 @@ static int _regulator_disable(struct regulator_dev *rdev)
 {
 	int ret = 0;
 
-	lockdep_assert_held_once(&rdev->mutex);
+	lockdep_assert_held_once(&rdev->mutex.base);
 
 	if (WARN(rdev->use_count <= 0,
 		 "unbalanced disables for %s\n", rdev_get_name(rdev)))
@@ -2407,6 +2577,12 @@ static int _regulator_disable(struct regulator_dev *rdev)
 		rdev->use_count--;
 	}
 
+	if (ret == 0 && rdev->coupling_desc.n_coupled > 1)
+		ret = regulator_balance_voltage(rdev, PM_SUSPEND_ON);
+
+	if (ret == 0 && rdev->supply)
+		ret = _regulator_disable(rdev->supply->rdev);
+
 	return ret;
 }
 
@@ -2425,17 +2601,15 @@ static int _regulator_disable(struct regulator_dev *rdev)
 int regulator_disable(struct regulator *regulator)
 {
 	struct regulator_dev *rdev = regulator->rdev;
+	struct ww_acquire_ctx ww_ctx;
 	int ret = 0;
 
 	if (regulator->always_on)
 		return 0;
 
-	mutex_lock(&rdev->mutex);
+	regulator_lock_dependent(rdev, &ww_ctx);
 	ret = _regulator_disable(rdev);
-	mutex_unlock(&rdev->mutex);
-
-	if (ret == 0 && rdev->supply)
-		regulator_disable(rdev->supply);
+	regulator_unlock_dependent(rdev, &ww_ctx);
 
 	return ret;
 }
@@ -2446,7 +2620,7 @@ static int _regulator_force_disable(struct regulator_dev *rdev)
 {
 	int ret = 0;
 
-	lockdep_assert_held_once(&rdev->mutex);
+	lockdep_assert_held_once(&rdev->mutex.base);
 
 	ret = _notifier_call_chain(rdev, REGULATOR_EVENT_FORCE_DISABLE |
 			REGULATOR_EVENT_PRE_DISABLE, NULL);
@@ -2479,12 +2653,15 @@ static int _regulator_force_disable(struct regulator_dev *rdev)
 int regulator_force_disable(struct regulator *regulator)
 {
 	struct regulator_dev *rdev = regulator->rdev;
+	struct ww_acquire_ctx ww_ctx;
 	int ret;
 
-	mutex_lock(&rdev->mutex);
+	regulator_lock_dependent(rdev, &ww_ctx);
 	regulator->uA_load = 0;
 	ret = _regulator_force_disable(regulator->rdev);
-	mutex_unlock(&rdev->mutex);
+	if (rdev->coupling_desc.n_coupled > 1)
+		regulator_balance_voltage(rdev, PM_SUSPEND_ON);
+	regulator_unlock_dependent(rdev, &ww_ctx);
 
 	if (rdev->supply)
 		while (rdev->open_count--)
@@ -2498,9 +2675,10 @@ static void regulator_disable_work(struct work_struct *work)
 {
 	struct regulator_dev *rdev = container_of(work, struct regulator_dev,
 						  disable_work.work);
+	struct ww_acquire_ctx ww_ctx;
 	int count, i, ret;
 
-	regulator_lock(rdev);
+	regulator_lock_dependent(rdev, &ww_ctx);
 
 	BUG_ON(!rdev->deferred_disables);
 
@@ -2521,7 +2699,10 @@ static void regulator_disable_work(struct work_struct *work)
 			rdev_err(rdev, "Deferred disable failed: %d\n", ret);
 	}
 
-	regulator_unlock(rdev);
+	if (rdev->coupling_desc.n_coupled > 1)
+		regulator_balance_voltage(rdev, PM_SUSPEND_ON);
+
+	regulator_unlock_dependent(rdev, &ww_ctx);
 
 	if (rdev->supply) {
 		for (i = 0; i < count; i++) {
@@ -2632,9 +2813,9 @@ int regulator_is_enabled(struct regulator *regulator)
 	if (regulator->always_on)
 		return 1;
 
-	mutex_lock(&regulator->rdev->mutex);
+	regulator_lock(regulator->rdev);
 	ret = _regulator_is_enabled(regulator->rdev);
-	mutex_unlock(&regulator->rdev->mutex);
+	regulator_unlock(regulator->rdev);
 
 	return ret;
 }
@@ -3048,8 +3229,6 @@ static int regulator_set_voltage_unlocked(struct regulator *regulator,
 	int ret = 0;
 	int old_min_uV, old_max_uV;
 	int current_uV;
-	int best_supply_uV = 0;
-	int supply_change_uV = 0;
 
 	/* If we're setting the same range as last time the change
 	 * should be a noop (some cpufreq implementations use the same
@@ -3089,10 +3268,27 @@ static int regulator_set_voltage_unlocked(struct regulator *regulator,
 	voltage->min_uV = min_uV;
 	voltage->max_uV = max_uV;
 
-	ret = regulator_check_consumers(rdev, &min_uV, &max_uV, state);
+	/* for not coupled regulators this will just set the voltage */
+	ret = regulator_balance_voltage(rdev, state);
 	if (ret < 0)
 		goto out2;
 
+out:
+	return 0;
+out2:
+	voltage->min_uV = old_min_uV;
+	voltage->max_uV = old_max_uV;
+
+	return ret;
+}
+
+static int regulator_set_voltage_rdev(struct regulator_dev *rdev, int min_uV,
+				      int max_uV, suspend_state_t state)
+{
+	int best_supply_uV = 0;
+	int supply_change_uV = 0;
+	int ret;
+
 	if (rdev->supply &&
 	    regulator_ops_is_valid(rdev->supply->rdev,
 				   REGULATOR_CHANGE_VOLTAGE) &&
@@ -3104,13 +3300,13 @@ static int regulator_set_voltage_unlocked(struct regulator *regulator,
 		selector = regulator_map_voltage(rdev, min_uV, max_uV);
 		if (selector < 0) {
 			ret = selector;
-			goto out2;
+			goto out;
 		}
 
 		best_supply_uV = _regulator_list_voltage(rdev, selector, 0);
 		if (best_supply_uV < 0) {
 			ret = best_supply_uV;
-			goto out2;
+			goto out;
 		}
 
 		best_supply_uV += rdev->desc->min_dropout_uV;
@@ -3118,7 +3314,7 @@ static int regulator_set_voltage_unlocked(struct regulator *regulator,
 		current_supply_uV = _regulator_get_voltage(rdev->supply->rdev);
 		if (current_supply_uV < 0) {
 			ret = current_supply_uV;
-			goto out2;
+			goto out;
 		}
 
 		supply_change_uV = best_supply_uV - current_supply_uV;
@@ -3130,7 +3326,7 @@ static int regulator_set_voltage_unlocked(struct regulator *regulator,
 		if (ret) {
 			dev_err(&rdev->dev, "Failed to increase supply voltage: %d\n",
 					ret);
-			goto out2;
+			goto out;
 		}
 	}
 
@@ -3140,7 +3336,7 @@ static int regulator_set_voltage_unlocked(struct regulator *regulator,
 		ret = _regulator_do_set_suspend_voltage(rdev, min_uV,
 							max_uV, state);
 	if (ret < 0)
-		goto out2;
+		goto out;
 
 	if (supply_change_uV < 0) {
 		ret = regulator_set_voltage_unlocked(rdev->supply,
@@ -3154,10 +3350,273 @@ static int regulator_set_voltage_unlocked(struct regulator *regulator,
 
 out:
 	return ret;
-out2:
-	voltage->min_uV = old_min_uV;
-	voltage->max_uV = old_max_uV;
+}
+
+static int regulator_limit_voltage_step(struct regulator_dev *rdev,
+					int *current_uV, int *min_uV)
+{
+	struct regulation_constraints *constraints = rdev->constraints;
+
+	/* Limit voltage change only if necessary */
+	if (!constraints->max_uV_step || !_regulator_is_enabled(rdev))
+		return 1;
+
+	if (*current_uV < 0) {
+		*current_uV = _regulator_get_voltage(rdev);
+
+		if (*current_uV < 0)
+			return *current_uV;
+	}
+
+	if (abs(*current_uV - *min_uV) <= constraints->max_uV_step)
+		return 1;
+
+	/* Clamp target voltage within the given step */
+	if (*current_uV < *min_uV)
+		*min_uV = min(*current_uV + constraints->max_uV_step,
+			      *min_uV);
+	else
+		*min_uV = max(*current_uV - constraints->max_uV_step,
+			      *min_uV);
+
+	return 0;
+}
+
+static int regulator_get_optimal_voltage(struct regulator_dev *rdev,
+					 int *current_uV,
+					 int *min_uV, int *max_uV,
+					 suspend_state_t state,
+					 int n_coupled)
+{
+	struct coupling_desc *c_desc = &rdev->coupling_desc;
+	struct regulator_dev **c_rdevs = c_desc->coupled_rdevs;
+	struct regulation_constraints *constraints = rdev->constraints;
+	int max_spread = constraints->max_spread;
+	int desired_min_uV = 0, desired_max_uV = INT_MAX;
+	int max_current_uV = 0, min_current_uV = INT_MAX;
+	int highest_min_uV = 0, target_uV, possible_uV;
+	int i, ret;
+	bool done;
+
+	*current_uV = -1;
+
+	/*
+	 * If there are no coupled regulators, simply set the voltage
+	 * demanded by consumers.
+	 */
+	if (n_coupled == 1) {
+		/*
+		 * If consumers don't provide any demands, set voltage
+		 * to min_uV
+		 */
+		desired_min_uV = constraints->min_uV;
+		desired_max_uV = constraints->max_uV;
+
+		ret = regulator_check_consumers(rdev,
+						&desired_min_uV,
+						&desired_max_uV, state);
+		if (ret < 0)
+			return ret;
+
+		possible_uV = desired_min_uV;
+		done = true;
+
+		goto finish;
+	}
+
+	/* Find highest min desired voltage */
+	for (i = 0; i < n_coupled; i++) {
+		int tmp_min = 0;
+		int tmp_max = INT_MAX;
+
+		lockdep_assert_held_once(&c_rdevs[i]->mutex.base);
+
+		ret = regulator_check_consumers(c_rdevs[i],
+						&tmp_min,
+						&tmp_max, state);
+		if (ret < 0)
+			return ret;
+
+		ret = regulator_check_voltage(c_rdevs[i], &tmp_min, &tmp_max);
+		if (ret < 0)
+			return ret;
 
+		highest_min_uV = max(highest_min_uV, tmp_min);
+
+		if (i == 0) {
+			desired_min_uV = tmp_min;
+			desired_max_uV = tmp_max;
+		}
+	}
+
+	/*
+	 * Let target_uV be equal to the desired one if possible.
+	 * If not, set it to minimum voltage, allowed by other coupled
+	 * regulators.
+	 */
+	target_uV = max(desired_min_uV, highest_min_uV - max_spread);
+
+	/*
+	 * Find min and max voltages, which currently aren't violating
+	 * max_spread.
+	 */
+	for (i = 1; i < n_coupled; i++) {
+		int tmp_act;
+
+		if (!_regulator_is_enabled(c_rdevs[i]))
+			continue;
+
+		tmp_act = _regulator_get_voltage(c_rdevs[i]);
+		if (tmp_act < 0)
+			return tmp_act;
+
+		min_current_uV = min(tmp_act, min_current_uV);
+		max_current_uV = max(tmp_act, max_current_uV);
+	}
+
+	/* There aren't any other regulators enabled */
+	if (max_current_uV == 0) {
+		possible_uV = target_uV;
+	} else {
+		/*
+		 * Correct target voltage, so as it currently isn't
+		 * violating max_spread
+		 */
+		possible_uV = max(target_uV, max_current_uV - max_spread);
+		possible_uV = min(possible_uV, min_current_uV + max_spread);
+	}
+
+	if (possible_uV > desired_max_uV)
+		return -EINVAL;
+
+	done = (possible_uV == target_uV);
+	desired_min_uV = possible_uV;
+
+finish:
+	/* Apply max_uV_step constraint if necessary */
+	if (state == PM_SUSPEND_ON) {
+		ret = regulator_limit_voltage_step(rdev, current_uV,
+						   &desired_min_uV);
+		if (ret < 0)
+			return ret;
+
+		if (ret == 0)
+			done = false;
+	}
+
+	/* Set current_uV if wasn't done earlier in the code and if necessary */
+	if (n_coupled > 1 && *current_uV == -1) {
+
+		if (_regulator_is_enabled(rdev)) {
+			ret = _regulator_get_voltage(rdev);
+			if (ret < 0)
+				return ret;
+
+			*current_uV = ret;
+		} else {
+			*current_uV = desired_min_uV;
+		}
+	}
+
+	*min_uV = desired_min_uV;
+	*max_uV = desired_max_uV;
+
+	return done;
+}
+
+static int regulator_balance_voltage(struct regulator_dev *rdev,
+				     suspend_state_t state)
+{
+	struct regulator_dev **c_rdevs;
+	struct regulator_dev *best_rdev;
+	struct coupling_desc *c_desc = &rdev->coupling_desc;
+	int i, ret, n_coupled, best_min_uV, best_max_uV, best_c_rdev;
+	bool best_c_rdev_done, c_rdev_done[MAX_COUPLED];
+	unsigned int delta, best_delta;
+
+	c_rdevs = c_desc->coupled_rdevs;
+	n_coupled = c_desc->n_coupled;
+
+	/*
+	 * If system is in a state other than PM_SUSPEND_ON, don't check
+	 * other coupled regulators.
+	 */
+	if (state != PM_SUSPEND_ON)
+		n_coupled = 1;
+
+	if (c_desc->n_resolved < n_coupled) {
+		rdev_err(rdev, "Not all coupled regulators registered\n");
+		return -EPERM;
+	}
+
+	for (i = 0; i < n_coupled; i++)
+		c_rdev_done[i] = false;
+
+	/*
+	 * Find the best possible voltage change on each loop. Leave the loop
+	 * if there isn't any possible change.
+	 */
+	do {
+		best_c_rdev_done = false;
+		best_delta = 0;
+		best_min_uV = 0;
+		best_max_uV = 0;
+		best_c_rdev = 0;
+		best_rdev = NULL;
+
+		/*
+		 * Find highest difference between optimal voltage
+		 * and current voltage.
+		 */
+		for (i = 0; i < n_coupled; i++) {
+			/*
+			 * optimal_uV is the best voltage that can be set for
+			 * i-th regulator at the moment without violating
+			 * max_spread constraint in order to balance
+			 * the coupled voltages.
+			 */
+			int optimal_uV = 0, optimal_max_uV = 0, current_uV = 0;
+
+			if (c_rdev_done[i])
+				continue;
+
+			ret = regulator_get_optimal_voltage(c_rdevs[i],
+							    &current_uV,
+							    &optimal_uV,
+							    &optimal_max_uV,
+							    state, n_coupled);
+			if (ret < 0)
+				goto out;
+
+			delta = abs(optimal_uV - current_uV);
+
+			if (delta && best_delta <= delta) {
+				best_c_rdev_done = ret;
+				best_delta = delta;
+				best_rdev = c_rdevs[i];
+				best_min_uV = optimal_uV;
+				best_max_uV = optimal_max_uV;
+				best_c_rdev = i;
+			}
+		}
+
+		/* Nothing to change, return successfully */
+		if (!best_rdev) {
+			ret = 0;
+			goto out;
+		}
+
+		ret = regulator_set_voltage_rdev(best_rdev, best_min_uV,
+						 best_max_uV, state);
+
+		if (ret < 0)
+			goto out;
+
+		c_rdev_done[best_c_rdev] = best_c_rdev_done;
+
+	} while (n_coupled > 1);
+
+out:
 	return ret;
 }
 
@@ -3181,14 +3640,15 @@ static int regulator_set_voltage_unlocked(struct regulator *regulator,
  */
 int regulator_set_voltage(struct regulator *regulator, int min_uV, int max_uV)
 {
-	int ret = 0;
+	struct ww_acquire_ctx ww_ctx;
+	int ret;
 
-	regulator_lock_supply(regulator->rdev);
+	regulator_lock_dependent(regulator->rdev, &ww_ctx);
 
 	ret = regulator_set_voltage_unlocked(regulator, min_uV, max_uV,
 					     PM_SUSPEND_ON);
 
-	regulator_unlock_supply(regulator->rdev);
+	regulator_unlock_dependent(regulator->rdev, &ww_ctx);
 
 	return ret;
 }
@@ -3260,18 +3720,19 @@ static int _regulator_set_suspend_voltage(struct regulator *regulator,
 int regulator_set_suspend_voltage(struct regulator *regulator, int min_uV,
 				  int max_uV, suspend_state_t state)
 {
-	int ret = 0;
+	struct ww_acquire_ctx ww_ctx;
+	int ret;
 
 	/* PM_SUSPEND_ON is handled by regulator_set_voltage() */
 	if (regulator_check_states(state) || state == PM_SUSPEND_ON)
 		return -EINVAL;
 
-	regulator_lock_supply(regulator->rdev);
+	regulator_lock_dependent(regulator->rdev, &ww_ctx);
 
 	ret = _regulator_set_suspend_voltage(regulator, min_uV,
 					     max_uV, state);
 
-	regulator_unlock_supply(regulator->rdev);
+	regulator_unlock_dependent(regulator->rdev, &ww_ctx);
 
 	return ret;
 }
@@ -3461,13 +3922,12 @@ static int _regulator_get_voltage(struct regulator_dev *rdev)
  */
 int regulator_get_voltage(struct regulator *regulator)
 {
+	struct ww_acquire_ctx ww_ctx;
 	int ret;
 
-	regulator_lock_supply(regulator->rdev);
-
+	regulator_lock_dependent(regulator->rdev, &ww_ctx);
 	ret = _regulator_get_voltage(regulator->rdev);
-
-	regulator_unlock_supply(regulator->rdev);
+	regulator_unlock_dependent(regulator->rdev, &ww_ctx);
 
 	return ret;
 }
@@ -4003,7 +4463,7 @@ EXPORT_SYMBOL_GPL(regulator_bulk_free);
 int regulator_notifier_call_chain(struct regulator_dev *rdev,
 				  unsigned long event, void *data)
 {
-	lockdep_assert_held_once(&rdev->mutex);
+	lockdep_assert_held_once(&rdev->mutex.base);
 
 	_notifier_call_chain(rdev, event, data);
 	return NOTIFY_DONE;
@@ -4192,7 +4652,7 @@ static int regulator_register_resolve_supply(struct device *dev, void *data)
 	return 0;
 }
 
-static int regulator_fill_coupling_array(struct regulator_dev *rdev)
+static void regulator_resolve_coupling(struct regulator_dev *rdev)
 {
 	struct coupling_desc *c_desc = &rdev->coupling_desc;
 	int n_coupled = c_desc->n_coupled;
@@ -4206,33 +4666,58 @@ static int regulator_fill_coupling_array(struct regulator_dev *rdev)
 
 		c_rdev = of_parse_coupled_regulator(rdev, i - 1);
 
-		if (c_rdev) {
-			c_desc->coupled_rdevs[i] = c_rdev;
-			c_desc->n_resolved++;
-		}
-	}
+		if (!c_rdev)
+			continue;
 
-	if (rdev->coupling_desc.n_resolved < n_coupled)
-		return -1;
-	else
-		return 0;
+		regulator_lock(c_rdev);
+
+		c_desc->coupled_rdevs[i] = c_rdev;
+		c_desc->n_resolved++;
+
+		regulator_unlock(c_rdev);
+
+		regulator_resolve_coupling(c_rdev);
+	}
 }
 
-static int regulator_register_fill_coupling_array(struct device *dev,
-						  void *data)
+static void regulator_remove_coupling(struct regulator_dev *rdev)
 {
-	struct regulator_dev *rdev = dev_to_rdev(dev);
+	struct coupling_desc *__c_desc, *c_desc = &rdev->coupling_desc;
+	struct regulator_dev *__c_rdev, *c_rdev;
+	unsigned int __n_coupled, n_coupled;
+	int i, k;
 
-	if (!IS_ENABLED(CONFIG_OF))
-		return 0;
+	n_coupled = c_desc->n_coupled;
 
-	if (regulator_fill_coupling_array(rdev))
-		rdev_dbg(rdev, "unable to resolve coupling\n");
+	for (i = 1; i < n_coupled; i++) {
+		c_rdev = c_desc->coupled_rdevs[i];
 
-	return 0;
+		if (!c_rdev)
+			continue;
+
+		regulator_lock(c_rdev);
+
+		__c_desc = &c_rdev->coupling_desc;
+		__n_coupled = __c_desc->n_coupled;
+
+		for (k = 1; k < __n_coupled; k++) {
+			__c_rdev = __c_desc->coupled_rdevs[k];
+
+			if (__c_rdev == rdev) {
+				__c_desc->coupled_rdevs[k] = NULL;
+				__c_desc->n_resolved--;
+				break;
+			}
+		}
+
+		regulator_unlock(c_rdev);
+
+		c_desc->coupled_rdevs[i] = NULL;
+		c_desc->n_resolved--;
+	}
 }
 
-static int regulator_resolve_coupling(struct regulator_dev *rdev)
+static int regulator_init_coupling(struct regulator_dev *rdev)
 {
 	int n_phandles;
 
@@ -4272,13 +4757,6 @@ static int regulator_resolve_coupling(struct regulator_dev *rdev)
 	if (!of_check_coupling_data(rdev))
 		return -EPERM;
 
-	/*
-	 * After everything has been checked, try to fill rdevs array
-	 * with pointers to regulators parsed from device tree. If some
-	 * regulators are not registered yet, retry in late init call
-	 */
-	regulator_fill_coupling_array(rdev);
-
 	return 0;
 }
 
@@ -4353,7 +4831,7 @@ regulator_register(const struct regulator_desc *regulator_desc,
 		rdev->dev.of_node = of_node_get(config->of_node);
 	}
 
-	mutex_init(&rdev->mutex);
+	ww_mutex_init(&rdev->mutex, &regulator_ww_class);
 	rdev->reg_data = config->driver_data;
 	rdev->owner = regulator_desc->owner;
 	rdev->desc = regulator_desc;
@@ -4415,11 +4893,8 @@ regulator_register(const struct regulator_desc *regulator_desc,
 	if (ret < 0)
 		goto wash;
 
-	mutex_lock(&regulator_list_mutex);
-	ret = regulator_resolve_coupling(rdev);
-	mutex_unlock(&regulator_list_mutex);
-
-	if (ret != 0)
+	ret = regulator_init_coupling(rdev);
+	if (ret < 0)
 		goto wash;
 
 	/* add consumers devices */
@@ -4453,6 +4928,11 @@ regulator_register(const struct regulator_desc *regulator_desc,
 
 	rdev_init_debugfs(rdev);
 
+	/* try to resolve regulators coupling since a new one was registered */
+	mutex_lock(&regulator_list_mutex);
+	regulator_resolve_coupling(rdev);
+	mutex_unlock(&regulator_list_mutex);
+
 	/* try to resolve regulators supply since a new one was registered */
 	class_for_each_device(&regulator_class, NULL, NULL,
 			      regulator_register_resolve_supply);
@@ -4491,15 +4971,19 @@ void regulator_unregister(struct regulator_dev *rdev)
 			regulator_disable(rdev->supply);
 		regulator_put(rdev->supply);
 	}
+
 	mutex_lock(&regulator_list_mutex);
+
 	debugfs_remove_recursive(rdev->debugfs);
 	flush_work(&rdev->disable_work.work);
 	WARN_ON(rdev->open_count);
+	regulator_remove_coupling(rdev);
 	unset_regulator_supplies(rdev);
 	list_del(&rdev->list);
 	regulator_ena_gpio_free(rdev);
-	mutex_unlock(&regulator_list_mutex);
 	device_unregister(&rdev->dev);
+
+	mutex_unlock(&regulator_list_mutex);
 }
 EXPORT_SYMBOL_GPL(regulator_unregister);
 
@@ -4707,8 +5191,6 @@ static void regulator_summary_show_subtree(struct seq_file *s,
 	if (!rdev)
 		return;
 
-	regulator_lock_nested(rdev, level);
-
 	opmode = _regulator_get_mode_unlocked(rdev);
 	seq_printf(s, "%*s%-*s %3d %4d %6d %7s ",
 		   level * 3 + 1, "",
@@ -4765,8 +5247,105 @@ static void regulator_summary_show_subtree(struct seq_file *s,
 
 	class_for_each_device(&regulator_class, NULL, &summary_data,
 			      regulator_summary_show_children);
+}
+
+struct summary_lock_data {
+	struct ww_acquire_ctx *ww_ctx;
+	struct regulator_dev **new_contended_rdev;
+	struct regulator_dev **old_contended_rdev;
+};
+
+static int regulator_summary_lock_one(struct device *dev, void *data)
+{
+	struct regulator_dev *rdev = dev_to_rdev(dev);
+	struct summary_lock_data *lock_data = data;
+	int ret = 0;
+
+	if (rdev != *lock_data->old_contended_rdev) {
+		ret = regulator_lock_nested(rdev, lock_data->ww_ctx);
+
+		if (ret == -EDEADLK)
+			*lock_data->new_contended_rdev = rdev;
+		else
+			WARN_ON_ONCE(ret);
+	} else {
+		*lock_data->old_contended_rdev = NULL;
+	}
+
+	return ret;
+}
+
+static int regulator_summary_unlock_one(struct device *dev, void *data)
+{
+	struct regulator_dev *rdev = dev_to_rdev(dev);
+	struct summary_lock_data *lock_data = data;
+
+	if (lock_data) {
+		if (rdev == *lock_data->new_contended_rdev)
+			return -EDEADLK;
+	}
 
 	regulator_unlock(rdev);
+
+	return 0;
+}
+
+static int regulator_summary_lock_all(struct ww_acquire_ctx *ww_ctx,
+				      struct regulator_dev **new_contended_rdev,
+				      struct regulator_dev **old_contended_rdev)
+{
+	struct summary_lock_data lock_data;
+	int ret;
+
+	lock_data.ww_ctx = ww_ctx;
+	lock_data.new_contended_rdev = new_contended_rdev;
+	lock_data.old_contended_rdev = old_contended_rdev;
+
+	ret = class_for_each_device(&regulator_class, NULL, &lock_data,
+				    regulator_summary_lock_one);
+	if (ret)
+		class_for_each_device(&regulator_class, NULL, &lock_data,
+				      regulator_summary_unlock_one);
+
+	return ret;
+}
+
+static void regulator_summary_lock(struct ww_acquire_ctx *ww_ctx)
+{
+	struct regulator_dev *new_contended_rdev = NULL;
+	struct regulator_dev *old_contended_rdev = NULL;
+	int err;
+
+	mutex_lock(&regulator_list_mutex);
+
+	ww_acquire_init(ww_ctx, &regulator_ww_class);
+
+	do {
+		if (new_contended_rdev) {
+			ww_mutex_lock_slow(&new_contended_rdev->mutex, ww_ctx);
+			old_contended_rdev = new_contended_rdev;
+			old_contended_rdev->ref_cnt++;
+		}
+
+		err = regulator_summary_lock_all(ww_ctx,
+						 &new_contended_rdev,
+						 &old_contended_rdev);
+
+		if (old_contended_rdev)
+			regulator_unlock(old_contended_rdev);
+
+	} while (err == -EDEADLK);
+
+	ww_acquire_done(ww_ctx);
+}
+
+static void regulator_summary_unlock(struct ww_acquire_ctx *ww_ctx)
+{
+	class_for_each_device(&regulator_class, NULL, NULL,
+			      regulator_summary_unlock_one);
+	ww_acquire_fini(ww_ctx);
+
+	mutex_unlock(&regulator_list_mutex);
 }
 
 static int regulator_summary_show_roots(struct device *dev, void *data)
@@ -4782,12 +5361,18 @@ static int regulator_summary_show_roots(struct device *dev, void *data)
 
 static int regulator_summary_show(struct seq_file *s, void *data)
 {
+	struct ww_acquire_ctx ww_ctx;
+
 	seq_puts(s, " regulator                      use open bypass  opmode voltage current     min     max\n");
 	seq_puts(s, "---------------------------------------------------------------------------------------\n");
 
+	regulator_summary_lock(&ww_ctx);
+
 	class_for_each_device(&regulator_class, NULL, s,
 			      regulator_summary_show_roots);
 
+	regulator_summary_unlock(&ww_ctx);
+
 	return 0;
 }
 
@@ -4908,9 +5493,6 @@ static int __init regulator_init_complete(void)
 	class_for_each_device(&regulator_class, NULL, NULL,
 			      regulator_late_cleanup);
 
-	class_for_each_device(&regulator_class, NULL, NULL,
-			      regulator_register_fill_coupling_array);
-
 	return 0;
 }
 late_initcall_sync(regulator_init_complete);

drivers/regulator/da9210-regulator.c

@@ -131,7 +131,7 @@ static irqreturn_t da9210_irq_handler(int irq, void *data)
 	if (error < 0)
 		goto error_i2c;
 
-	mutex_lock(&chip->rdev->mutex);
+	regulator_lock(chip->rdev);
 
 	if (val & DA9210_E_OVCURR) {
 		regulator_notifier_call_chain(chip->rdev,
@@ -157,7 +157,7 @@ static irqreturn_t da9210_irq_handler(int irq, void *data)
 		handled |= DA9210_E_VMAX;
 	}
 
-	mutex_unlock(&chip->rdev->mutex);
+	regulator_unlock(chip->rdev);
 
 	if (handled) {
 		/* Clear handled events */

drivers/regulator/of_regulator.c

@@ -171,6 +171,10 @@ static void of_get_regulation_constraints(struct device_node *np,
 				  &pval))
 		constraints->max_spread = pval;
 
+	if (!of_property_read_u32(np, "regulator-max-step-microvolt",
+				  &pval))
+		constraints->max_uV_step = pval;
+
 	constraints->over_current_protection = of_property_read_bool(np,
 					"regulator-over-current-protection");
 

drivers/regulator/stpmic1_regulator.c

@@ -489,14 +489,14 @@ static irqreturn_t stpmic1_curlim_irq_handler(int irq, void *data)
 {
 	struct regulator_dev *rdev = (struct regulator_dev *)data;
 
-	mutex_lock(&rdev->mutex);
+	regulator_lock(rdev, NULL);
 
 	/* Send an overcurrent notification */
 	regulator_notifier_call_chain(rdev,
 				      REGULATOR_EVENT_OVER_CURRENT,
 				      NULL);
 
-	mutex_unlock(&rdev->mutex);
+	regulator_unlock(rdev);
 
 	return IRQ_HANDLED;
 }

drivers/regulator/wm8350-regulator.c

@@ -1153,7 +1153,7 @@ static irqreturn_t pmic_uv_handler(int irq, void *data)
 {
 	struct regulator_dev *rdev = (struct regulator_dev *)data;
 
-	mutex_lock(&rdev->mutex);
+	regulator_lock(rdev);
 	if (irq == WM8350_IRQ_CS1 || irq == WM8350_IRQ_CS2)
 		regulator_notifier_call_chain(rdev,
 					      REGULATOR_EVENT_REGULATION_OUT,
@@ -1162,7 +1162,7 @@ static irqreturn_t pmic_uv_handler(int irq, void *data)
 		regulator_notifier_call_chain(rdev,
 					      REGULATOR_EVENT_UNDER_VOLTAGE,
 					      NULL);
-	mutex_unlock(&rdev->mutex);
+	regulator_unlock(rdev);
 
 	return IRQ_HANDLED;
 }

include/linux/regulator/driver.h

@@ -15,11 +15,12 @@
 #ifndef __LINUX_REGULATOR_DRIVER_H_
 #define __LINUX_REGULATOR_DRIVER_H_
 
-#define MAX_COUPLED		4
+#define MAX_COUPLED		2
 
 #include <linux/device.h>
 #include <linux/notifier.h>
 #include <linux/regulator/consumer.h>
+#include <linux/ww_mutex.h>
 
 struct gpio_desc;
 struct regmap;
@@ -462,7 +463,7 @@ struct regulator_dev {
 	struct coupling_desc coupling_desc;
 
 	struct blocking_notifier_head notifier;
-	struct mutex mutex; /* consumer lock */
+	struct ww_mutex mutex; /* consumer lock */
 	struct task_struct *mutex_owner;
 	int ref_cnt;
 	struct module *owner;
@@ -545,4 +546,7 @@ int regulator_set_active_discharge_regmap(struct regulator_dev *rdev,
 					  bool enable);
 void *regulator_get_init_drvdata(struct regulator_init_data *reg_init_data);
 
+void regulator_lock(struct regulator_dev *rdev);
+void regulator_unlock(struct regulator_dev *rdev);
+
 #endif

include/linux/regulator/machine.h

@@ -158,6 +158,9 @@ struct regulation_constraints {
 	/* used for coupled regulators */
 	int max_spread;
 
+	/* used for changing voltage in steps */
+	int max_uV_step;
+
 	/* valid regulator operating modes for this machine */
 	unsigned int valid_modes_mask;