[PATCH] regulator: core: Change voltage setting path

From: Maciej Purski
Date: Mon Apr 23 2018 - 10:33:42 EST

On Odroid XU3/4 and other Exynos5422 based boards there is a case, that
different devices on the board are supplied by different regulators
with non-fixed voltages. If one of these devices temporarily requires
higher voltage, there might occur a situation that the spread between
two devices' voltages is so high, that there is a risk of changing
'high' and 'low' states on the interconnection between devices powered
by those regulators.

Uncoupled regulators should be a special case of coupled regulators, so
they should share a common voltage setting path. When enabling,
disabling or setting voltage of a coupled regulator, all coupled
regulators should be locked. Regulator's supplies should be locked, when
setting voltage of a single regulator. Enabling a coupled regulator or
setting its voltage should not be possible if some of its coupled
regulators, has not been registered.

Add function for locking coupled regulators and supplies. Extract
a new function regulator_set_voltage_rdev() from
regulator_set_voltage_unlocked(), which is called when setting
voltage of a single regulator.

Signed-off-by: Maciej Purski <m.purski@xxxxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
---
drivers/regulator/core.c | 159 ++++++++++++++++++++++++++-------------
1 file changed, 107 insertions(+), 52 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 225eaca24921..ac97e21bff10 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -107,6 +107,9 @@ 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);
@@ -198,37 +201,66 @@ static void regulator_unlock(struct regulator_dev *rdev)
}
}

-/**
- * regulator_lock_supply - lock a regulator and its supplies
- * @rdev: regulator source
- */
-static void regulator_lock_supply(struct regulator_dev *rdev)
+static int regulator_lock_recursive(struct regulator_dev *rdev,
+ unsigned int subclass)
{
+ struct regulator_dev *c_rdev;
int i;

- for (i = 0; rdev; rdev = rdev_get_supply(rdev), i++)
- regulator_lock_nested(rdev, i);
+ for (i = 0; i < rdev->coupling_desc.n_coupled; i++) {
+ c_rdev = rdev->coupling_desc.coupled_rdevs[i];
+
+ if (!c_rdev)
+ continue;
+
+ regulator_lock_nested(c_rdev, subclass++);
+
+ if (c_rdev->supply)
+ subclass =
+ regulator_lock_recursive(c_rdev->supply->rdev,
+ subclass);
+ }
+
+ return subclass;
}

/**
- * regulator_unlock_supply - unlock a regulator and its supplies
- * @rdev: regulator source
+ * regulator_unlock_dependent - unlock regulator's suppliers and coupled
+ * regulators
+ * @rdev: regulator source
+ *
+ * Unlock all regulators related with rdev by coupling or suppling.
*/
-static void regulator_unlock_supply(struct regulator_dev *rdev)
+static void regulator_unlock_dependent(struct regulator_dev *rdev)
{
- struct regulator *supply;
+ struct regulator_dev *c_rdev;
+ int i;

- while (1) {
- regulator_unlock(rdev);
- supply = rdev->supply;
+ for (i = 0; i < rdev->coupling_desc.n_coupled; i++) {
+ c_rdev = rdev->coupling_desc.coupled_rdevs[i];

- if (!rdev->supply)
- return;
+ if (!c_rdev)
+ continue;
+
+ regulator_unlock(c_rdev);

- rdev = supply->rdev;
+ if (c_rdev->supply)
+ regulator_unlock_dependent(c_rdev->supply->rdev);
}
}

+/**
+ * regulator_lock_dependent - lock regulator's suppliers and coupled regulators
+ * @rdev: regulator source
+ *
+ * This function as a wrapper on regulator_lock_recursive(), which locks
+ * all regulators related with rdev by coupling or suppling.
+ */
+static inline void regulator_lock_dependent(struct regulator_dev *rdev)
+{
+ regulator_lock_recursive(rdev, 0);
+}
+
/**
* of_get_regulator - get a regulator device node based on supply name
* @dev: Device pointer for the consumer (of regulator) device
@@ -2261,6 +2293,11 @@ int regulator_enable(struct regulator *regulator)
struct regulator_dev *rdev = regulator->rdev;
int ret = 0;

+ if (rdev->coupling_desc.n_resolved != rdev->coupling_desc.n_coupled) {
+ rdev_err(rdev, "not all coupled regulators registered\n");
+ return -EPERM;
+ }
+
if (regulator->always_on)
return 0;

@@ -2270,9 +2307,12 @@ int regulator_enable(struct regulator *regulator)
return ret;
}

- mutex_lock(&rdev->mutex);
+ regulator_lock_dependent(rdev);
ret = _regulator_enable(rdev);
- mutex_unlock(&rdev->mutex);
+ /* balance only if there are regulators coupled */
+ if (rdev->coupling_desc.n_coupled > 1)
+ regulator_balance_voltage(rdev, PM_SUSPEND_ON);
+ regulator_unlock_dependent(rdev);

if (ret != 0 && rdev->supply)
regulator_disable(rdev->supply);
@@ -2378,9 +2418,11 @@ int regulator_disable(struct regulator *regulator)
if (regulator->always_on)
return 0;

- mutex_lock(&rdev->mutex);
+ regulator_lock_dependent(rdev);
ret = _regulator_disable(rdev);
- mutex_unlock(&rdev->mutex);
+ if (rdev->coupling_desc.n_coupled > 1)
+ regulator_balance_voltage(rdev, PM_SUSPEND_ON);
+ regulator_unlock_dependent(rdev);

if (ret == 0 && rdev->supply)
regulator_disable(rdev->supply);
@@ -2429,10 +2471,12 @@ int regulator_force_disable(struct regulator *regulator)
struct regulator_dev *rdev = regulator->rdev;
int ret;

- mutex_lock(&rdev->mutex);
+ regulator_lock_dependent(rdev);
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);

if (rdev->supply)
while (rdev->open_count--)
@@ -2580,9 +2624,9 @@ int regulator_is_enabled(struct regulator *regulator)
if (regulator->always_on)
return 1;

- mutex_lock(&regulator->rdev->mutex);
+ regulator_lock_dependent(regulator->rdev);
ret = _regulator_is_enabled(regulator->rdev);
- mutex_unlock(&regulator->rdev->mutex);
+ regulator_unlock_dependent(regulator->rdev);

return ret;
}
@@ -2991,8 +3035,12 @@ 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 (rdev->coupling_desc.n_resolved != rdev->coupling_desc.n_coupled) {
+ rdev_err(rdev, "not all coupled regulators registered\n");
+ ret = -EPERM;
+ goto out;
+ }

/* If we're setting the same range as last time the change
* should be a noop (some cpufreq implementations use the same
@@ -3036,6 +3084,27 @@ static int regulator_set_voltage_unlocked(struct regulator *regulator,
if (ret < 0)
goto out2;

+ /* 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) &&
@@ -3047,13 +3116,13 @@ 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;
@@ -3061,7 +3130,7 @@ 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;
@@ -3073,7 +3142,7 @@ 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;
}
}

@@ -3083,7 +3152,7 @@ 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,
@@ -3096,11 +3165,6 @@ 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;
-
return ret;
}

@@ -3274,17 +3338,8 @@ static int regulator_balance_voltage(struct regulator_dev *rdev,
goto out;
}

- /*
- * Lock just the supply regulators, as the regulator itself
- * is already locked by regulator_lock_coupled().
- */
- if (best_rdev->supply)
- regulator_lock_supply(best_rdev->supply->rdev);
-
ret = regulator_set_voltage_rdev(best_rdev, best_uV,
best_uV, state);
- if (best_rdev->supply)
- regulator_unlock_supply(best_rdev->supply->rdev);

if (ret < 0)
goto out;
@@ -3316,12 +3371,12 @@ int regulator_set_voltage(struct regulator *regulator, int min_uV, int max_uV)
{
int ret = 0;

- regulator_lock_supply(regulator->rdev);
+ regulator_lock_dependent(regulator->rdev);

ret = regulator_set_voltage_unlocked(regulator, min_uV, max_uV,
PM_SUSPEND_ON);

- regulator_unlock_supply(regulator->rdev);
+ regulator_unlock_dependent(regulator->rdev);

return ret;
}
@@ -3399,12 +3454,12 @@ int regulator_set_suspend_voltage(struct regulator *regulator, int min_uV,
if (regulator_check_states(state) || state == PM_SUSPEND_ON)
return -EINVAL;

- regulator_lock_supply(regulator->rdev);
+ regulator_lock_dependent(regulator->rdev);

ret = _regulator_set_suspend_voltage(regulator, min_uV,
max_uV, state);

- regulator_unlock_supply(regulator->rdev);
+ regulator_unlock_dependent(regulator->rdev);

return ret;
}
@@ -3596,11 +3651,11 @@ int regulator_get_voltage(struct regulator *regulator)
{
int ret;

- regulator_lock_supply(regulator->rdev);
+ regulator_lock_dependent(regulator->rdev);

ret = _regulator_get_voltage(regulator->rdev);

- regulator_unlock_supply(regulator->rdev);
+ regulator_unlock_dependent(regulator->rdev);

return ret;
}
--
2.17.0