Commit 871f5650 authored by Guodong Xu's avatar Guodong Xu Committed by Mark Brown
Browse files

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



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: default avatarGuodong Xu <guodong.xu@linaro.org>
Signed-off-by: default avatarMark Brown <broonie@linaro.org>
parent 79fd1141

drivers/regulator/core.c

+31 −0
Original line number Diff line number Diff line
@@ -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;

include/linux/regulator/driver.h

+6 −0
Original line number Diff line number Diff line
@@ -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 *

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