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regulator: core: add guard delay between calling regulator_disable and _enable

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Some regulator require a minimum delay between its disable and next enable.
This is to avoid damages when out-of-range frequent disable/enable of a
single regulator can bring to the regulator chip.

Add @off_on_delay to struct regulator_desc. Device drivers' can use this field
to set this guard time.

Add @last_off_jiffy to struct regulator_dev. When @off_on_delay is set by
driver, regulator core can store its last off (disable) time into this field.

Signed-off-by: Guodong Xu <guodong.xu@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>
This commit is contained in:
Guodong Xu 2014-08-13 19:33:40 +08:00 committed by Mark Brown
parent 79fd114161
commit 871f565055
2 changed files with 37 additions and 0 deletions
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31
drivers/regulator/core.c
View File

@ -1813,6 +1813,31 @@ static int _regulator_do_enable(struct regulator_dev *rdev)
trace_regulator_enable(rdev_get_name(rdev));
if (rdev->desc->off_on_delay) {
/* if needed, keep a distance of off_on_delay from last time
* this regulator was disabled.
*/
unsigned long start_jiffy = jiffies;
unsigned long intended, max_delay, remaining;
max_delay = usecs_to_jiffies(rdev->desc->off_on_delay);
intended = rdev->last_off_jiffy + max_delay;
if (time_before(start_jiffy, intended)) {
/* calc remaining jiffies to deal with one-time
* timer wrapping.
* in case of multiple timer wrapping, either it can be
* detected by out-of-range remaining, or it cannot be
* detected and we gets a panelty of
* _regulator_enable_delay().
*/
remaining = intended - start_jiffy;
if (remaining <= max_delay)
_regulator_enable_delay(
jiffies_to_usecs(remaining));
}
}
if (rdev->ena_pin) {
ret = regulator_ena_gpio_ctrl(rdev, true);
if (ret < 0)
@ -1925,6 +1950,12 @@ static int _regulator_do_disable(struct regulator_dev *rdev)
return ret;
}
/* cares about last_off_jiffy only if off_on_delay is required by
* device.
*/
if (rdev->desc->off_on_delay)
rdev->last_off_jiffy = jiffies;
trace_regulator_disable_complete(rdev_get_name(rdev));
return 0;

6
include/linux/regulator/driver.h
View File

@ -238,6 +238,7 @@ enum regulator_type {
* @bypass_val_off: Disabling value for control when using regmap set_bypass
*
* @enable_time: Time taken for initial enable of regulator (in uS).
* @off_on_delay: guard time (in uS), before re-enabling a regulator
*/
struct regulator_desc {
const char *name;
@ -276,6 +277,8 @@ struct regulator_desc {
unsigned int bypass_val_off;
unsigned int enable_time;
unsigned int off_on_delay;
};
/**
@ -348,6 +351,9 @@ struct regulator_dev {
struct regulator_enable_gpio *ena_pin;
unsigned int ena_gpio_state:1;
/* time when this regulator was disabled last time */
unsigned long last_off_jiffy;
};
struct regulator_dev *