Merge tag 'regulator-v5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator

Pull regulator updates from Mark Brown:
 "A couple of new features in the core, the most interesting one being
  support for complex regulator coupling configurations initially
  targeted at nVidia Tegra SoCs, and some new drivers but otherwise
  quite a quiet release.

  Summary:

   - Core support for gradual ramping of voltages for devices that can't
     manage large changes in hardware from Bartosz Golaszewski.

   - Core support for systems that have complex coupling requirements
     best described via code, contributed by Dmitry Osipenko.

   - New drivers for Dialog SLG51000, Qualcomm PM8005 and ST
     Microelectronics STM32-Booster"

* tag 'regulator-v5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator: (52 commits)
  regulator: max77650: use vsel_step
  regulator: implement selector stepping
  regulator: max77650: add MODULE_ALIAS()
  regulator: max77620: remove redundant assignment to variable ret
  dt-bindings: regulator: add support for the stm32-booster
  regulator: add support for the stm32-booster
  regulator: s2mps11: Adjust supported buck voltages to real values
  regulator: s2mps11: Fix buck7 and buck8 wrong voltages
  gpio: Fix return value mismatch of function gpiod_get_from_of_node()
  regulator: core: Expose some of core functions needed by couplers
  regulator: core: Introduce API for regulators coupling customization
  regulator: s2mps11: Add support for disabling S2MPS11 regulators in suspend
  regulator: s2mps11: Reduce number of rdev_get_id() calls
  regulator: qcom_spmi: Do NULL check for lvs
  regulator: qcom_spmi: Fix math of spmi_regulator_set_voltage_time_sel
  regulator: da9061/62: Adjust LDO voltage selection minimum value
  regulator: s2mps11: Fix ERR_PTR dereference on GPIO lookup failure
  regulator: qcom_spmi: add PMS405 SPMI regulator
  dt-bindings: qcom_spmi: Document pms405 support
  arm64: dts: msm8998-mtp: Add pm8005_s1 regulator
  ...

1 files changed, 216 insertions, 62 deletions

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index c894cf0d8a28..86ae1825cec1 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1,12 +1,11 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
-/*
- * core.c  --  Voltage/Current Regulator framework.
- *
- * Copyright 2007, 2008 Wolfson Microelectronics PLC.
- * Copyright 2008 SlimLogic Ltd.
- *
- * Author: Liam Girdwood <lrg@slimlogic.co.uk>
- */
+//
+// core.c  --  Voltage/Current Regulator framework.
+//
+// Copyright 2007, 2008 Wolfson Microelectronics PLC.
+// Copyright 2008 SlimLogic Ltd.
+//
+// Author: Liam Girdwood <lrg@slimlogic.co.uk>
 
 #include <linux/kernel.h>
 #include <linux/init.h>
@@ -23,6 +22,7 @@
 #include <linux/regmap.h>
 #include <linux/regulator/of_regulator.h>
 #include <linux/regulator/consumer.h>
+#include <linux/regulator/coupler.h>
 #include <linux/regulator/driver.h>
 #include <linux/regulator/machine.h>
 #include <linux/module.h>
@@ -50,6 +50,7 @@ static DEFINE_MUTEX(regulator_list_mutex);
 static LIST_HEAD(regulator_map_list);
 static LIST_HEAD(regulator_ena_gpio_list);
 static LIST_HEAD(regulator_supply_alias_list);
+static LIST_HEAD(regulator_coupler_list);
 static bool has_full_constraints;
 
 static struct dentry *debugfs_root;
@@ -93,7 +94,6 @@ struct regulator_supply_alias {
 
 static int _regulator_is_enabled(struct regulator_dev *rdev);
 static int _regulator_disable(struct regulator *regulator);
-static int _regulator_get_voltage(struct regulator_dev *rdev);
 static int _regulator_get_current_limit(struct regulator_dev *rdev);
 static unsigned int _regulator_get_mode(struct regulator_dev *rdev);
 static int _notifier_call_chain(struct regulator_dev *rdev,
@@ -102,15 +102,12 @@ 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);
 static void _regulator_put(struct regulator *regulator);
 
-static const char *rdev_get_name(struct regulator_dev *rdev)
+const char *rdev_get_name(struct regulator_dev *rdev)
 {
 	if (rdev->constraints && rdev->constraints->name)
 		return rdev->constraints->name;
@@ -424,8 +421,8 @@ static struct device_node *of_get_regulator(struct device *dev, const char *supp
 }
 
 /* Platform voltage constraint check */
-static int regulator_check_voltage(struct regulator_dev *rdev,
-				   int *min_uV, int *max_uV)
+int regulator_check_voltage(struct regulator_dev *rdev,
+			    int *min_uV, int *max_uV)
 {
 	BUG_ON(*min_uV > *max_uV);
 
@@ -457,9 +454,9 @@ static int regulator_check_states(suspend_state_t state)
 /* Make sure we select a voltage that suits the needs of all
  * regulator consumers
  */
-static int regulator_check_consumers(struct regulator_dev *rdev,
-				     int *min_uV, int *max_uV,
-				     suspend_state_t state)
+int regulator_check_consumers(struct regulator_dev *rdev,
+			      int *min_uV, int *max_uV,
+			      suspend_state_t state)
 {
 	struct regulator *regulator;
 	struct regulator_voltage *voltage;
@@ -570,7 +567,7 @@ static ssize_t regulator_uV_show(struct device *dev,
 	ssize_t ret;
 
 	regulator_lock(rdev);
-	ret = sprintf(buf, "%d\n", _regulator_get_voltage(rdev));
+	ret = sprintf(buf, "%d\n", regulator_get_voltage_rdev(rdev));
 	regulator_unlock(rdev);
 
 	return ret;
@@ -941,7 +938,7 @@ static int drms_uA_update(struct regulator_dev *rdev)
 			rdev_err(rdev, "failed to set load %d\n", current_uA);
 	} else {
 		/* get output voltage */
-		output_uV = _regulator_get_voltage(rdev);
+		output_uV = regulator_get_voltage_rdev(rdev);
 		if (output_uV <= 0) {
 			rdev_err(rdev, "invalid output voltage found\n");
 			return -EINVAL;
@@ -1054,7 +1051,7 @@ static void print_constraints(struct regulator_dev *rdev)
 
 	if (!constraints->min_uV ||
 	    constraints->min_uV != constraints->max_uV) {
-		ret = _regulator_get_voltage(rdev);
+		ret = regulator_get_voltage_rdev(rdev);
 		if (ret > 0)
 			count += scnprintf(buf + count, len - count,
 					   "at %d mV ", ret / 1000);
@@ -1113,7 +1110,7 @@ static int machine_constraints_voltage(struct regulator_dev *rdev,
 	if (rdev->constraints->apply_uV &&
 	    rdev->constraints->min_uV && rdev->constraints->max_uV) {
 		int target_min, target_max;
-		int current_uV = _regulator_get_voltage(rdev);
+		int current_uV = regulator_get_voltage_rdev(rdev);
 
 		if (current_uV == -ENOTRECOVERABLE) {
 			/* This regulator can't be read and must be initialized */
@@ -1123,7 +1120,7 @@ static int machine_constraints_voltage(struct regulator_dev *rdev,
 			_regulator_do_set_voltage(rdev,
 						  rdev->constraints->min_uV,
 						  rdev->constraints->max_uV);
-			current_uV = _regulator_get_voltage(rdev);
+			current_uV = regulator_get_voltage_rdev(rdev);
 		}
 
 		if (current_uV < 0) {
@@ -1645,9 +1642,9 @@ static int _regulator_get_enable_time(struct regulator_dev *rdev)
 {
 	if (rdev->constraints && rdev->constraints->enable_time)
 		return rdev->constraints->enable_time;
-	if (!rdev->desc->ops->enable_time)
-		return rdev->desc->enable_time;
-	return rdev->desc->ops->enable_time(rdev);
+	if (rdev->desc->ops->enable_time)
+		return rdev->desc->ops->enable_time(rdev);
+	return rdev->desc->enable_time;
 }
 
 static struct regulator_supply_alias *regulator_find_supply_alias(
@@ -3065,7 +3062,7 @@ static int _regulator_call_set_voltage(struct regulator_dev *rdev,
 	struct pre_voltage_change_data data;
 	int ret;
 
-	data.old_uV = _regulator_get_voltage(rdev);
+	data.old_uV = regulator_get_voltage_rdev(rdev);
 	data.min_uV = min_uV;
 	data.max_uV = max_uV;
 	ret = _notifier_call_chain(rdev, REGULATOR_EVENT_PRE_VOLTAGE_CHANGE,
@@ -3089,7 +3086,7 @@ static int _regulator_call_set_voltage_sel(struct regulator_dev *rdev,
 	struct pre_voltage_change_data data;
 	int ret;
 
-	data.old_uV = _regulator_get_voltage(rdev);
+	data.old_uV = regulator_get_voltage_rdev(rdev);
 	data.min_uV = uV;
 	data.max_uV = uV;
 	ret = _notifier_call_chain(rdev, REGULATOR_EVENT_PRE_VOLTAGE_CHANGE,
@@ -3107,6 +3104,66 @@ static int _regulator_call_set_voltage_sel(struct regulator_dev *rdev,
 	return ret;
 }
 
+static int _regulator_set_voltage_sel_step(struct regulator_dev *rdev,
+					   int uV, int new_selector)
+{
+	const struct regulator_ops *ops = rdev->desc->ops;
+	int diff, old_sel, curr_sel, ret;
+
+	/* Stepping is only needed if the regulator is enabled. */
+	if (!_regulator_is_enabled(rdev))
+		goto final_set;
+
+	if (!ops->get_voltage_sel)
+		return -EINVAL;
+
+	old_sel = ops->get_voltage_sel(rdev);
+	if (old_sel < 0)
+		return old_sel;
+
+	diff = new_selector - old_sel;
+	if (diff == 0)
+		return 0; /* No change needed. */
+
+	if (diff > 0) {
+		/* Stepping up. */
+		for (curr_sel = old_sel + rdev->desc->vsel_step;
+		     curr_sel < new_selector;
+		     curr_sel += rdev->desc->vsel_step) {
+			/*
+			 * Call the callback directly instead of using
+			 * _regulator_call_set_voltage_sel() as we don't
+			 * want to notify anyone yet. Same in the branch
+			 * below.
+			 */
+			ret = ops->set_voltage_sel(rdev, curr_sel);
+			if (ret)
+				goto try_revert;
+		}
+	} else {
+		/* Stepping down. */
+		for (curr_sel = old_sel - rdev->desc->vsel_step;
+		     curr_sel > new_selector;
+		     curr_sel -= rdev->desc->vsel_step) {
+			ret = ops->set_voltage_sel(rdev, curr_sel);
+			if (ret)
+				goto try_revert;
+		}
+	}
+
+final_set:
+	/* The final selector will trigger the notifiers. */
+	return _regulator_call_set_voltage_sel(rdev, uV, new_selector);
+
+try_revert:
+	/*
+	 * At least try to return to the previous voltage if setting a new
+	 * one failed.
+	 */
+	(void)ops->set_voltage_sel(rdev, old_sel);
+	return ret;
+}
+
 static int _regulator_set_voltage_time(struct regulator_dev *rdev,
 				       int old_uV, int new_uV)
 {
@@ -3142,7 +3199,7 @@ static int _regulator_do_set_voltage(struct regulator_dev *rdev,
 	unsigned int selector;
 	int old_selector = -1;
 	const struct regulator_ops *ops = rdev->desc->ops;
-	int old_uV = _regulator_get_voltage(rdev);
+	int old_uV = regulator_get_voltage_rdev(rdev);
 
 	trace_regulator_set_voltage(rdev_get_name(rdev), min_uV, max_uV);
 
@@ -3169,7 +3226,7 @@ static int _regulator_do_set_voltage(struct regulator_dev *rdev,
 				best_val = ops->list_voltage(rdev,
 							     selector);
 			else
-				best_val = _regulator_get_voltage(rdev);
+				best_val = regulator_get_voltage_rdev(rdev);
 		}
 
 	} else if (ops->set_voltage_sel) {
@@ -3180,6 +3237,9 @@ static int _regulator_do_set_voltage(struct regulator_dev *rdev,
 				selector = ret;
 				if (old_selector == selector)
 					ret = 0;
+				else if (rdev->desc->vsel_step)
+					ret = _regulator_set_voltage_sel_step(
+						rdev, best_val, selector);
 				else
 					ret = _regulator_call_set_voltage_sel(
 						rdev, best_val, selector);
@@ -3288,7 +3348,7 @@ static int regulator_set_voltage_unlocked(struct regulator *regulator,
 	 * changing the voltage.
 	 */
 	if (!regulator_ops_is_valid(rdev, REGULATOR_CHANGE_VOLTAGE)) {
-		current_uV = _regulator_get_voltage(rdev);
+		current_uV = regulator_get_voltage_rdev(rdev);
 		if (min_uV <= current_uV && current_uV <= max_uV) {
 			voltage->min_uV = min_uV;
 			voltage->max_uV = max_uV;
@@ -3325,8 +3385,8 @@ out:
 	return ret;
 }
 
-static int regulator_set_voltage_rdev(struct regulator_dev *rdev, int min_uV,
-				      int max_uV, suspend_state_t state)
+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;
@@ -3354,7 +3414,7 @@ static int regulator_set_voltage_rdev(struct regulator_dev *rdev, int min_uV,
 
 		best_supply_uV += rdev->desc->min_dropout_uV;
 
-		current_supply_uV = _regulator_get_voltage(rdev->supply->rdev);
+		current_supply_uV = regulator_get_voltage_rdev(rdev->supply->rdev);
 		if (current_supply_uV < 0) {
 			ret = current_supply_uV;
 			goto out;
@@ -3405,7 +3465,7 @@ static int regulator_limit_voltage_step(struct regulator_dev *rdev,
 		return 1;
 
 	if (*current_uV < 0) {
-		*current_uV = _regulator_get_voltage(rdev);
+		*current_uV = regulator_get_voltage_rdev(rdev);
 
 		if (*current_uV < 0)
 			return *current_uV;
@@ -3434,11 +3494,10 @@ static int regulator_get_optimal_voltage(struct regulator_dev *rdev,
 	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;
+	int i, ret, max_spread;
 	bool done;
 
 	*current_uV = -1;
@@ -3492,6 +3551,8 @@ static int regulator_get_optimal_voltage(struct regulator_dev *rdev,
 		}
 	}
 
+	max_spread = constraints->max_spread[0];
+
 	/*
 	 * Let target_uV be equal to the desired one if possible.
 	 * If not, set it to minimum voltage, allowed by other coupled
@@ -3509,7 +3570,7 @@ static int regulator_get_optimal_voltage(struct regulator_dev *rdev,
 		if (!_regulator_is_enabled(c_rdevs[i]))
 			continue;
 
-		tmp_act = _regulator_get_voltage(c_rdevs[i]);
+		tmp_act = regulator_get_voltage_rdev(c_rdevs[i]);
 		if (tmp_act < 0)
 			return tmp_act;
 
@@ -3551,7 +3612,7 @@ finish:
 	if (n_coupled > 1 && *current_uV == -1) {
 
 		if (_regulator_is_enabled(rdev)) {
-			ret = _regulator_get_voltage(rdev);
+			ret = regulator_get_voltage_rdev(rdev);
 			if (ret < 0)
 				return ret;
 
@@ -3573,9 +3634,11 @@ static int regulator_balance_voltage(struct regulator_dev *rdev,
 	struct regulator_dev **c_rdevs;
 	struct regulator_dev *best_rdev;
 	struct coupling_desc *c_desc = &rdev->coupling_desc;
+	struct regulator_coupler *coupler = c_desc->coupler;
 	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;
+	unsigned long c_rdev_done = 0;
+	bool best_c_rdev_done;
 
 	c_rdevs = c_desc->coupled_rdevs;
 	n_coupled = c_desc->n_coupled;
@@ -3592,8 +3655,9 @@ static int regulator_balance_voltage(struct regulator_dev *rdev,
 		return -EPERM;
 	}
 
-	for (i = 0; i < n_coupled; i++)
-		c_rdev_done[i] = false;
+	/* Invoke custom balancer for customized couplers */
+	if (coupler && coupler->balance_voltage)
+		return coupler->balance_voltage(coupler, rdev, state);
 
 	/*
 	 * Find the best possible voltage change on each loop. Leave the loop
@@ -3620,7 +3684,7 @@ static int regulator_balance_voltage(struct regulator_dev *rdev,
 			 */
 			int optimal_uV = 0, optimal_max_uV = 0, current_uV = 0;
 
-			if (c_rdev_done[i])
+			if (test_bit(i, &c_rdev_done))
 				continue;
 
 			ret = regulator_get_optimal_voltage(c_rdevs[i],
@@ -3655,7 +3719,8 @@ static int regulator_balance_voltage(struct regulator_dev *rdev,
 		if (ret < 0)
 			goto out;
 
-		c_rdev_done[best_c_rdev] = best_c_rdev_done;
+		if (best_c_rdev_done)
+			set_bit(best_c_rdev, &c_rdev_done);
 
 	} while (n_coupled > 1);
 
@@ -3911,7 +3976,7 @@ out:
 }
 EXPORT_SYMBOL_GPL(regulator_sync_voltage);
 
-static int _regulator_get_voltage(struct regulator_dev *rdev)
+int regulator_get_voltage_rdev(struct regulator_dev *rdev)
 {
 	int sel, ret;
 	bool bypassed;
@@ -3928,7 +3993,7 @@ static int _regulator_get_voltage(struct regulator_dev *rdev)
 				return -EPROBE_DEFER;
 			}
 
-			return _regulator_get_voltage(rdev->supply->rdev);
+			return regulator_get_voltage_rdev(rdev->supply->rdev);
 		}
 	}
 
@@ -3944,7 +4009,7 @@ static int _regulator_get_voltage(struct regulator_dev *rdev)
 	} else if (rdev->desc->fixed_uV && (rdev->desc->n_voltages == 1)) {
 		ret = rdev->desc->fixed_uV;
 	} else if (rdev->supply) {
-		ret = _regulator_get_voltage(rdev->supply->rdev);
+		ret = regulator_get_voltage_rdev(rdev->supply->rdev);
 	} else {
 		return -EINVAL;
 	}
@@ -3969,7 +4034,7 @@ int regulator_get_voltage(struct regulator *regulator)
 	int ret;
 
 	regulator_lock_dependent(regulator->rdev, &ww_ctx);
-	ret = _regulator_get_voltage(regulator->rdev);
+	ret = regulator_get_voltage_rdev(regulator->rdev);
 	regulator_unlock_dependent(regulator->rdev, &ww_ctx);
 
 	return ret;
@@ -4707,8 +4772,60 @@ static int regulator_register_resolve_supply(struct device *dev, void *data)
 	return 0;
 }
 
+int regulator_coupler_register(struct regulator_coupler *coupler)
+{
+	mutex_lock(&regulator_list_mutex);
+	list_add_tail(&coupler->list, &regulator_coupler_list);
+	mutex_unlock(&regulator_list_mutex);
+
+	return 0;
+}
+
+static struct regulator_coupler *
+regulator_find_coupler(struct regulator_dev *rdev)
+{
+	struct regulator_coupler *coupler;
+	int err;
+
+	/*
+	 * Note that regulators are appended to the list and the generic
+	 * coupler is registered first, hence it will be attached at last
+	 * if nobody cared.
+	 */
+	list_for_each_entry_reverse(coupler, &regulator_coupler_list, list) {
+		err = coupler->attach_regulator(coupler, rdev);
+		if (!err) {
+			if (!coupler->balance_voltage &&
+			    rdev->coupling_desc.n_coupled > 2)
+				goto err_unsupported;
+
+			return coupler;
+		}
+
+		if (err < 0)
+			return ERR_PTR(err);
+
+		if (err == 1)
+			continue;
+
+		break;
+	}
+
+	return ERR_PTR(-EINVAL);
+
+err_unsupported:
+	if (coupler->detach_regulator)
+		coupler->detach_regulator(coupler, rdev);
+
+	rdev_err(rdev,
+		"Voltage balancing for multiple regulator couples is unimplemented\n");
+
+	return ERR_PTR(-EPERM);
+}
+
 static void regulator_resolve_coupling(struct regulator_dev *rdev)
 {
+	struct regulator_coupler *coupler = rdev->coupling_desc.coupler;
 	struct coupling_desc *c_desc = &rdev->coupling_desc;
 	int n_coupled = c_desc->n_coupled;
 	struct regulator_dev *c_rdev;
@@ -4724,6 +4841,12 @@ static void regulator_resolve_coupling(struct regulator_dev *rdev)
 		if (!c_rdev)
 			continue;
 
+		if (c_rdev->coupling_desc.coupler != coupler) {
+			rdev_err(rdev, "coupler mismatch with %s\n",
+				 rdev_get_name(c_rdev));
+			return;
+		}
+
 		regulator_lock(c_rdev);
 
 		c_desc->coupled_rdevs[i] = c_rdev;
@@ -4737,10 +4860,12 @@ static void regulator_resolve_coupling(struct regulator_dev *rdev)
 
 static void regulator_remove_coupling(struct regulator_dev *rdev)
 {
+	struct regulator_coupler *coupler = rdev->coupling_desc.coupler;
 	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;
+	int err;
 
 	n_coupled = c_desc->n_coupled;
 
@@ -4770,21 +4895,33 @@ static void regulator_remove_coupling(struct regulator_dev *rdev)
 		c_desc->coupled_rdevs[i] = NULL;
 		c_desc->n_resolved--;
 	}
+
+	if (coupler && coupler->detach_regulator) {
+		err = coupler->detach_regulator(coupler, rdev);
+		if (err)
+			rdev_err(rdev, "failed to detach from coupler: %d\n",
+				 err);
+	}
+
+	kfree(rdev->coupling_desc.coupled_rdevs);
+	rdev->coupling_desc.coupled_rdevs = NULL;
 }
 
 static int regulator_init_coupling(struct regulator_dev *rdev)
 {
-	int n_phandles;
+	int err, n_phandles;
+	size_t alloc_size;
 
 	if (!IS_ENABLED(CONFIG_OF))
 		n_phandles = 0;
 	else
 		n_phandles = of_get_n_coupled(rdev);
 
-	if (n_phandles + 1 > MAX_COUPLED) {
-		rdev_err(rdev, "too many regulators coupled\n");
-		return -EPERM;
-	}
+	alloc_size = sizeof(*rdev) * (n_phandles + 1);
+
+	rdev->coupling_desc.coupled_rdevs = kzalloc(alloc_size, GFP_KERNEL);
+	if (!rdev->coupling_desc.coupled_rdevs)
+		return -ENOMEM;
 
 	/*
 	 * Every regulator should always have coupling descriptor filled with
@@ -4798,23 +4935,35 @@ static int regulator_init_coupling(struct regulator_dev *rdev)
 	if (n_phandles == 0)
 		return 0;
 
-	/* regulator, which can't change its voltage, can't be coupled */
-	if (!regulator_ops_is_valid(rdev, REGULATOR_CHANGE_VOLTAGE)) {
-		rdev_err(rdev, "voltage operation not allowed\n");
+	if (!of_check_coupling_data(rdev))
 		return -EPERM;
-	}
 
-	if (rdev->constraints->max_spread <= 0) {
-		rdev_err(rdev, "wrong max_spread value\n");
-		return -EPERM;
+	rdev->coupling_desc.coupler = regulator_find_coupler(rdev);
+	if (IS_ERR(rdev->coupling_desc.coupler)) {
+		err = PTR_ERR(rdev->coupling_desc.coupler);
+		rdev_err(rdev, "failed to get coupler: %d\n", err);
+		return err;
 	}
 
-	if (!of_check_coupling_data(rdev))
+	return 0;
+}
+
+static int generic_coupler_attach(struct regulator_coupler *coupler,
+				  struct regulator_dev *rdev)
+{
+	if (rdev->coupling_desc.n_coupled > 2) {
+		rdev_err(rdev,
+			 "Voltage balancing for multiple regulator couples is unimplemented\n");
 		return -EPERM;
+	}
 
 	return 0;
 }
 
+static struct regulator_coupler generic_regulator_coupler = {
+	.attach_regulator = generic_coupler_attach,
+};
+
 /**
  * regulator_register - register regulator
  * @regulator_desc: regulator to register
@@ -4976,7 +5125,9 @@ regulator_register(const struct regulator_desc *regulator_desc,
 	if (ret < 0)
 		goto wash;
 
+	mutex_lock(&regulator_list_mutex);
 	ret = regulator_init_coupling(rdev);
+	mutex_unlock(&regulator_list_mutex);
 	if (ret < 0)
 		goto wash;
 
@@ -5025,6 +5176,7 @@ regulator_register(const struct regulator_desc *regulator_desc,
 unset_supplies:
 	mutex_lock(&regulator_list_mutex);
 	unset_regulator_supplies(rdev);
+	regulator_remove_coupling(rdev);
 	mutex_unlock(&regulator_list_mutex);
 wash:
 	kfree(rdev->constraints);
@@ -5278,7 +5430,7 @@ static void regulator_summary_show_subtree(struct seq_file *s,
 		   rdev->use_count, rdev->open_count, rdev->bypass_count,
 		   regulator_opmode_to_str(opmode));
 
-	seq_printf(s, "%5dmV ", _regulator_get_voltage(rdev) / 1000);
+	seq_printf(s, "%5dmV ", regulator_get_voltage_rdev(rdev) / 1000);
 	seq_printf(s, "%5dmA ",
 		   _regulator_get_current_limit_unlocked(rdev) / 1000);
 
@@ -5480,6 +5632,8 @@ static int __init regulator_init(void)
 #endif
 	regulator_dummy_init();
 
+	regulator_coupler_register(&generic_regulator_coupler);
+
 	return ret;
 }