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Subject[PATCH v4 7/7] regulator: core: Change voltage setting path
Date
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. 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@samsung.com>
---
drivers/regulator/core.c | 103 +++++++++++++++++++++++++++++++++++++----------
1 file changed, 82 insertions(+), 21 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 0492b0e..ce90246 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);
@@ -180,6 +183,36 @@ static void regulator_unlock_supply(struct regulator_dev *rdev)
}

/**
+ * regulator_lock_coupled - lock a group of coupled regulators
+ * @rdev: regulator source
+ */
+static void regulator_lock_coupled(struct regulator_dev *rdev)
+{
+ struct coupling_desc *c_desc = &rdev->coupling_desc;
+ int n_coupled = c_desc->n_coupled;
+ int i;
+
+ for (i = 0; i < n_coupled; i++)
+ if (c_desc->coupled_rdevs[i])
+ mutex_lock_nested(&c_desc->coupled_rdevs[i]->mutex, i);
+}
+
+/**
+ * regulator_unlock_coupled - unlock a group of coupled regulators
+ * @rdev: regulator source
+ */
+static void regulator_unlock_coupled(struct regulator_dev *rdev)
+{
+ struct coupling_desc *c_desc = &rdev->coupling_desc;
+ int n_coupled = c_desc->n_coupled;
+ int i;
+
+ for (i = 0; i < n_coupled; i++)
+ if (c_desc->coupled_rdevs[i])
+ mutex_unlock(&c_desc->coupled_rdevs[i]->mutex);
+}
+
+/**
* of_get_regulator - get a regulator device node based on supply name
* @dev: Device pointer for the consumer (of regulator) device
* @supply: regulator supply name
@@ -2184,6 +2217,11 @@ 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;

@@ -2193,9 +2231,10 @@ int regulator_enable(struct regulator *regulator)
return ret;
}

- mutex_lock(&rdev->mutex);
+ regulator_lock_coupled(rdev);
ret = _regulator_enable(rdev);
- mutex_unlock(&rdev->mutex);
+ regulator_balance_voltage(rdev, PM_SUSPEND_ON);
+ regulator_unlock_coupled(rdev);

if (ret != 0 && rdev->supply)
regulator_disable(rdev->supply);
@@ -2301,9 +2340,10 @@ int regulator_disable(struct regulator *regulator)
if (regulator->always_on)
return 0;

- mutex_lock(&rdev->mutex);
+ regulator_lock_coupled(rdev);
ret = _regulator_disable(rdev);
- mutex_unlock(&rdev->mutex);
+ regulator_balance_voltage(rdev, PM_SUSPEND_ON);
+ regulator_unlock_coupled(rdev);

if (ret == 0 && rdev->supply)
regulator_disable(rdev->supply);
@@ -2352,10 +2392,11 @@ int regulator_force_disable(struct regulator *regulator)
struct regulator_dev *rdev = regulator->rdev;
int ret;

- mutex_lock(&rdev->mutex);
+ regulator_lock_coupled(rdev);
regulator->uA_load = 0;
ret = _regulator_force_disable(regulator->rdev);
- mutex_unlock(&rdev->mutex);
+ regulator_balance_voltage(rdev, PM_SUSPEND_ON);
+ regulator_unlock_coupled(rdev);

if (rdev->supply)
while (rdev->open_count--)
@@ -2888,8 +2929,12 @@ 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
@@ -2933,6 +2978,27 @@ 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) &&
@@ -2944,13 +3010,13 @@ 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(regulator, selector, 0);
+ 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;
@@ -2958,7 +3024,7 @@ 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;
@@ -2970,13 +3036,13 @@ 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;
}
}

ret = _regulator_do_set_voltage(rdev, min_uV, max_uV);
if (ret < 0)
- goto out2;
+ goto out;

if (supply_change_uV < 0) {
ret = regulator_set_voltage_unlocked(rdev->supply,
@@ -2990,11 +3056,6 @@ 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;
}

static int regulator_get_optimal_voltage(struct regulator_dev *rdev)
@@ -3209,12 +3270,12 @@ int regulator_set_voltage(struct regulator *regulator, int min_uV, int max_uV)
{
int ret = 0;

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

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

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

return ret;
}
--
2.7.4
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