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Subject[PATCH 1/2] regulator: implement selector stepping
Date
From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Some regulators require that the requested voltage be reached gradually
by setting all or some of the intermediate values. Implement a new field
in the regulator description struct that allows users to specify the
number of selectors by which the regulator API should step when ramping
the voltage up/down.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
drivers/regulator/core.c | 63 ++++++++++++++++++++++++++++++++
include/linux/regulator/driver.h | 6 +++
2 files changed, 69 insertions(+)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 9d3ed13b7f12..df82e2a8442a 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -3106,6 +3106,66 @@ 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)
{
@@ -3179,6 +3239,9 @@ 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);
diff --git a/include/linux/regulator/driver.h b/include/linux/regulator/driver.h
index 377da2357118..f0d7b0496e54 100644
--- a/include/linux/regulator/driver.h
+++ b/include/linux/regulator/driver.h
@@ -286,6 +286,11 @@ enum regulator_type {
* @vsel_range_mask: Mask for register bitfield used for range selector
* @vsel_reg: Register for selector when using regulator_regmap_X_voltage_
* @vsel_mask: Mask for register bitfield used for selector
+ * @vsel_step: Specify the resolution of selector stepping when setting
+ * voltage. If 0, then no stepping is done (requested selector is
+ * set directly), if >0 then the regulator API will ramp the
+ * voltage up/down gradually each time increasing/decreasing the
+ * selector by the specified step value.
* @csel_reg: Register for current limit selector using regmap set_current_limit
* @csel_mask: Mask for register bitfield used for current limit selector
* @apply_reg: Register for initiate voltage change on the output when
@@ -360,6 +365,7 @@ struct regulator_desc {
unsigned int vsel_range_mask;
unsigned int vsel_reg;
unsigned int vsel_mask;
+ unsigned int vsel_step;
unsigned int csel_reg;
unsigned int csel_mask;
unsigned int apply_reg;
--
2.21.0
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