Commit 557acb3d authored by Amjad Ouled-Ameur's avatar Amjad Ouled-Ameur Committed by Philipp Zabel
Browse files

reset: make shared pulsed reset controls re-triggerable 



The current reset framework API does not allow to release what is done by
reset_control_reset(), IOW decrement triggered_count. Add the new
reset_control_rearm() call to do so.

When reset_control_reset() has been called once, the counter
triggered_count, in the reset framework, is incremented i.e the resource
under the reset is in-use and the reset should not be done again.
reset_control_rearm() would be the way to state that the resource is
no longer used and, that from the caller's perspective, the reset can be
fired again if necessary.

Signed-off-by: default avatarAmjad Ouled-Ameur <aouledameur@baylibre.com>
Reported-by: default avatarJerome Brunet <jbrunet@baylibre.com>
Signed-off-by: default avatarPhilipp Zabel <p.zabel@pengutronix.de>
parent 3650b228

drivers/reset/core.c

+73 −0
Original line number Diff line number Diff line
@@ -208,6 +208,39 @@ static int reset_control_array_reset(struct reset_control_array *resets) 
	return 0;

}



static int reset_control_array_rearm(struct reset_control_array *resets)

{

	struct reset_control *rstc;

	int i;



	for (i = 0; i < resets->num_rstcs; i++) {

		rstc = resets->rstc[i];



		if (!rstc)

			continue;



		if (WARN_ON(IS_ERR(rstc)))

			return -EINVAL;



		if (rstc->shared) {

			if (WARN_ON(atomic_read(&rstc->deassert_count) != 0))

				return -EINVAL;

		} else {

			if (!rstc->acquired)

				return -EPERM;

		}

	}



	for (i = 0; i < resets->num_rstcs; i++) {

		rstc = resets->rstc[i];



		if (rstc && rstc->shared)

			WARN_ON(atomic_dec_return(&rstc->triggered_count) < 0);

	}



	return 0;

}



static int reset_control_array_assert(struct reset_control_array *resets)

{

	int ret, i;
@@ -325,6 +358,46 @@ int reset_control_reset(struct reset_control *rstc) 
}

EXPORT_SYMBOL_GPL(reset_control_reset);



/**

 * reset_control_rearm - allow shared reset line to be re-triggered"

 * @rstc: reset controller

 *

 * On a shared reset line the actual reset pulse is only triggered once for the

 * lifetime of the reset_control instance, except if this call is used.

 *

 * Calls to this function must be balanced with calls to reset_control_reset,

 * a warning is thrown in case triggered_count ever dips below 0.

 *

 * Consumers must not use reset_control_(de)assert on shared reset lines when

 * reset_control_reset or reset_control_rearm have been used.

 *

 * If rstc is NULL the function will just return 0.

 */

int reset_control_rearm(struct reset_control *rstc)

{

	if (!rstc)

		return 0;



	if (WARN_ON(IS_ERR(rstc)))

		return -EINVAL;



	if (reset_control_is_array(rstc))

		return reset_control_array_rearm(rstc_to_array(rstc));



	if (rstc->shared) {

		if (WARN_ON(atomic_read(&rstc->deassert_count) != 0))

			return -EINVAL;



		WARN_ON(atomic_dec_return(&rstc->triggered_count) < 0);

	} else {

		if (!rstc->acquired)

			return -EPERM;

	}



	return 0;

}

EXPORT_SYMBOL_GPL(reset_control_rearm);



/**

 * reset_control_assert - asserts the reset line

 * @rstc: reset controller

include/linux/reset.h

+1 −0
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ struct reset_control; 
#ifdef CONFIG_RESET_CONTROLLER



int reset_control_reset(struct reset_control *rstc);

int reset_control_rearm(struct reset_control *rstc);

int reset_control_assert(struct reset_control *rstc);

int reset_control_deassert(struct reset_control *rstc);

int reset_control_status(struct reset_control *rstc);

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