regulator: Add ramp_delay configuration to constraints

For some hardwares ramp_delay for BUCKs is a configurable parameter which can
be configured through DT or board file.This patch adds ramp_delay to regulator
constraints and allow user to configure it for regulators which supports this
feature, through DT or board file. It will provide two ways of setting the
ramp_delay for a regulator:
	First, by setting it as constraints in board file(for configurable
regulators) and set_machine_constraints() will take care of setting it on
hardware by calling(the provided) .set_ramp_delay() operation(callback).
	Second, by setting it as data in regulator_desc(as fixed/default
ramp_delay rate) for a regulator in driver.

regulator_set_voltage_time_sel() will give preference to
constraints->ramp_delay while reading ramp_delay rate for regulator. Similarly
users should also take care accordingly while refering ramp_delay rate(in case
of implementing their private .set_voltage_time_sel() callbacks for different
regulators).

[Rewrote subject for 80 columns -- broonie]

Signed-off-by: Yadwinder Singh Brar <yadi.brar@samsung.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/regulator/driver.h b/include/linux/regulator/driver.h
index ae5c25379237..ddc155d262da 100644
--- a/include/linux/regulator/driver.h
+++ b/include/linux/regulator/driver.h
@@ -67,6 +67,8 @@ enum regulator_status {
  *
  * @enable_time: Time taken for the regulator voltage output voltage to
  *               stabilise after being enabled, in microseconds.
+ * @set_ramp_delay: Set the ramp delay for the regulator. The driver should
+ *              select ramp delay equal to or less than(closest) ramp_delay.
  * @set_voltage_time_sel: Time taken for the regulator voltage output voltage
  *               to stabilise after being set to a new value, in microseconds.
  *               The function provides the from and to voltage selector, the
@@ -113,6 +115,7 @@ struct regulator_ops {
 
         /* Time taken to enable or set voltage on the regulator */
         int (*enable_time) (struct regulator_dev *);
+        int (*set_ramp_delay) (struct regulator_dev *, int ramp_delay);
         int (*set_voltage_time_sel) (struct regulator_dev *,
                                      unsigned int old_selector,
                                      unsigned int new_selector);