regulator: add support for ramp delay

Add support for ramp delay which can be configured:
- by passing value from constraints.
- by initialising descriptor.

Also add generic API to provide ramp delay support function.

Change-Id: If22880672aa5cbdf930dd010e4b05c3083028e0b
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Reviewed-on: http://git-master/r/197459
Reviewed-by: Automatic_Commit_Validation_User

1 files changed, 48 insertions, 0 deletions

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index de6be430f106..658ad1347c84 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1080,6 +1080,14 @@ static int set_machine_constraints(struct regulator_dev *rdev,
 		}
 	}
 
+	if (rdev->constraints->ramp_delay && ops->set_ramp_delay) {
+		ret = ops->set_ramp_delay(rdev, rdev->constraints->ramp_delay);
+		if (ret < 0) {
+			rdev_err(rdev, "failed to set ramp_delay\n");
+			goto out;
+		}
+	}
+
 	print_constraints(rdev);
 	return 0;
 out:
@@ -2172,6 +2180,46 @@ int regulator_set_voltage_time(struct regulator *regulator,
 EXPORT_SYMBOL_GPL(regulator_set_voltage_time);
 
 /**
+ * regulator_set_voltage_time_sel - get raise/fall time
+ * @rdev: regulator source device
+ * @old_selector: selector for starting voltage
+ * @new_selector: selector for target voltage
+ *
+ * Provided with the starting and target voltage selectors, this function
+ * returns time in microseconds required to rise or fall to this new voltage
+ *
+ * Drivers providing ramp_delay in regulation_constraints can use this as their
+ * set_voltage_time_sel() operation.
+ */
+int regulator_set_voltage_time_sel(struct regulator_dev *rdev,
+				   unsigned int old_selector,
+				   unsigned int new_selector)
+{
+	unsigned int ramp_delay = 0;
+	int old_volt, new_volt;
+
+	if (rdev->constraints->ramp_delay)
+		ramp_delay = rdev->constraints->ramp_delay;
+	else if (rdev->desc->ramp_delay)
+		ramp_delay = rdev->desc->ramp_delay;
+
+	if (ramp_delay == 0) {
+		rdev_warn(rdev, "ramp_delay not set\n");
+		return 0;
+	}
+
+	/* sanity check */
+	if (!rdev->desc->ops->list_voltage)
+		return -EINVAL;
+
+	old_volt = rdev->desc->ops->list_voltage(rdev, old_selector);
+	new_volt = rdev->desc->ops->list_voltage(rdev, new_selector);
+
+	return DIV_ROUND_UP(abs(new_volt - old_volt), ramp_delay);
+}
+EXPORT_SYMBOL_GPL(regulator_set_voltage_time_sel);
+
+/**
  * regulator_sync_voltage - re-apply last regulator output voltage
  * @regulator: regulator source
  *