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authorMark Brown <broonie@opensource.wolfsonmicro.com>2009-12-21 12:21:52 +0000
committerLiam Girdwood <lrg@slimlogic.co.uk>2010-03-03 14:49:23 +0000
commit31aae2beeb3d601d556b6a8c39085940ad1e9f42 (patch)
tree7a608cabf48e020c5d23e8a96a59c095f0946d2b /drivers/regulator
parent84b6826306119dc3c41ef9d7ed6c408112f63301 (diff)
downloadop-kernel-dev-31aae2beeb3d601d556b6a8c39085940ad1e9f42.zip
op-kernel-dev-31aae2beeb3d601d556b6a8c39085940ad1e9f42.tar.gz
regulator: Allow regulators to specify the time taken to ramp on enable
Regulators may sometimes take longer to enable than the control operation used to do so, either because the regulator has ramp rate control used to limit inrush current or because the control operation is very fast (GPIO being the most common example of this). In order to ensure that consumers do not rely on the regulator before it is enabled provide an enable_time() operation and have the core delay for that time before returning to the caller. This is implemented as a function since the ramp rate may be specified in voltage per unit time and therefore the time depend on the configuration. In future it would be desirable to allow the bulk operations to run the delays for multiple enables in parallel but this is not currently supported. Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Diffstat (limited to 'drivers/regulator')
-rw-r--r--drivers/regulator/core.c41
1 files changed, 35 insertions, 6 deletions
diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 6d2ce8a..ca8e164 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);
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