2 files changed, 41 insertions, 6 deletions

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 6d2ce8a0533..ca8e1642538 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -19,6 +19,7 @@
 #include <linux/err.h>
 #include <linux/mutex.h>
 #include <linux/suspend.h>
+#include <linux/delay.h>
 #include <linux/regulator/consumer.h>
 #include <linux/regulator/driver.h>
 #include <linux/regulator/machine.h>
@@ -1084,6 +1085,13 @@ overflow_err:
         return NULL;
 }
 
+static int _regulator_get_enable_time(struct regulator_dev *rdev)
+{
+        if (!rdev->desc->ops->enable_time)
+                return 0;
+        return rdev->desc->ops->enable_time(rdev);
+}
+
 /* Internal regulator request function */
 static struct regulator *_regulator_get(struct device *dev, const char *id,
                                         int exclusive)
@@ -1251,7 +1259,7 @@ static int _regulator_can_change_status(struct regulator_dev *rdev)
 /* locks held by regulator_enable() */
 static int _regulator_enable(struct regulator_dev *rdev)
 {
-        int ret;
+        int ret, delay;
 
         /* do we need to enable the supply regulator first */
         if (rdev->supply) {
@@ -1275,13 +1283,34 @@ static int _regulator_enable(struct regulator_dev *rdev)
                         if (!_regulator_can_change_status(rdev))
                                 return -EPERM;
 
-                        if (rdev->desc->ops->enable) {
-                                ret = rdev->desc->ops->enable(rdev);
-                                if (ret < 0)
-                                        return ret;
-                        } else {
+                        if (!rdev->desc->ops->enable)
                                 return -EINVAL;
+
+                        /* Query before enabling in case configuration
+                         * dependant.  */
+                        ret = _regulator_get_enable_time(rdev);
+                        if (ret >= 0) {
+                                delay = ret;
+                        } else {
+                                printk(KERN_WARNING
+                                        "%s: enable_time() failed for %s: %d\n",
+                                        __func__, rdev_get_name(rdev),
+                                        ret);
+                                delay = 0;
                         }
+
+                        /* Allow the regulator to ramp; it would be useful
+                         * to extend this for bulk operations so that the
+                         * regulators can ramp together.  */
+                        ret = rdev->desc->ops->enable(rdev);
+                        if (ret < 0)
+                                return ret;
+
+                        if (delay >= 1000)
+                                mdelay(delay / 1000);
+                        else if (delay)
+                                udelay(delay);
+
                 } else if (ret < 0) {
                         printk(KERN_ERR "%s: is_enabled() failed for %s: %d\n",
                                __func__, rdev_get_name(rdev), ret);
diff --git a/include/linux/regulator/driver.h b/include/linux/regulator/driver.h
index 31f2055eae2..592cd7c642c 100644
--- a/include/linux/regulator/driver.h
+++ b/include/linux/regulator/driver.h
@@ -58,6 +58,9 @@ enum regulator_status {
  * @get_optimum_mode: Get the most efficient operating mode for the regulator
  *                    when running with the specified parameters.
  *
+ * @enable_time: Time taken for the regulator voltage output voltage to
+ *               stabalise after being enabled, in microseconds.
+ *
  * @set_suspend_voltage: Set the voltage for the regulator when the system
  *                       is suspended.
  * @set_suspend_enable: Mark the regulator as enabled when the system is
@@ -93,6 +96,9 @@ 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 */
+        int (*enable_time) (struct regulator_dev *);
+
         /* report regulator status ... most other accessors report
          * control inputs, this reports results of combining inputs
          * from Linux (and other sources) with the actual load.