regulator: add set_voltage_time_sel infrastructure

This makes it possible to set the stabilization time for voltage
regulators in the same manner as enable_time(). The interface
only supports regulators that implements fixed selectors.

Cc: Bengt Jonsson <bengt.g.jonsson@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>

2 files changed, 34 insertions, 2 deletions

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index e611f6797e6a..e7e4460dcb92 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1629,6 +1629,7 @@ static int _regulator_do_set_voltage(struct regulator_dev *rdev,
                                      int min_uV, int max_uV)
 {
         int ret;
+        int delay = 0;
         unsigned int selector;
 
         trace_regulator_set_voltage(rdev_get_name(rdev), min_uV, max_uV);
@@ -1662,6 +1663,22 @@ static int _regulator_do_set_voltage(struct regulator_dev *rdev,
                         }
                 }
 
+                /*
+                 * If we can't obtain the old selector there is not enough
+                 * info to call set_voltage_time_sel().
+                 */
+                if (rdev->desc->ops->set_voltage_time_sel &&
+                    rdev->desc->ops->get_voltage_sel) {
+                        unsigned int old_selector = 0;
+
+                        ret = rdev->desc->ops->get_voltage_sel(rdev);
+                        if (ret < 0)
+                                return ret;
+                        old_selector = ret;
+                        delay = rdev->desc->ops->set_voltage_time_sel(rdev,
+                                                old_selector, selector);
+                }
+
                 if (best_val != INT_MAX) {
                         ret = rdev->desc->ops->set_voltage_sel(rdev, selector);
                         selector = best_val;
@@ -1672,6 +1689,14 @@ static int _regulator_do_set_voltage(struct regulator_dev *rdev,
                 ret = -EINVAL;
         }
 
+        /* Insert any necessary delays */
+        if (delay >= 1000) {
+                mdelay(delay / 1000);
+                udelay(delay % 1000);
+        } else if (delay) {
+                udelay(delay);
+        }
+
         if (ret == 0)
                 _notifier_call_chain(rdev, REGULATOR_EVENT_VOLTAGE_CHANGE,
                                      NULL);
diff --git a/include/linux/regulator/driver.h b/include/linux/regulator/driver.h
index b8ed16a33c47..6c433b89c80d 100644
--- a/include/linux/regulator/driver.h
+++ b/include/linux/regulator/driver.h
@@ -63,7 +63,11 @@ enum regulator_status {
  *                    when running with the specified parameters.
  *
  * @enable_time: Time taken for the regulator voltage output voltage to
- *               stabalise after being enabled, in microseconds.
+ *               stabilise after being enabled, in microseconds.
+ * @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
+ *               function should return the worst case.
  *
  * @set_suspend_voltage: Set the voltage for the regulator when the system
  *                       is suspended.
@@ -103,8 +107,11 @@ struct regulator_ops {
         int (*set_mode) (struct regulator_dev *, unsigned int mode);
         unsigned int (*get_mode) (struct regulator_dev *);
 
-        /* Time taken to enable the regulator */
+        /* Time taken to enable or set voltage on the regulator */
         int (*enable_time) (struct regulator_dev *);
+        int (*set_voltage_time_sel) (struct regulator_dev *,
+                                     unsigned int old_selector,
+                                     unsigned int new_selector);
 
         /* report regulator status ... most other accessors report
          * control inputs, this reports results of combining inputs