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: Amjad Ouled-Ameur <aouledameur@xxxxxxxxxxxx> Reported-by: Jerome Brunet <jbrunet@xxxxxxxxxxxx> --- Change since v1: [0] * Renamed the new call from reset_control_(array_)resettable to reset_control_(array_)rearm * Open-coded reset_control_array_rearm to check for errors before decrementing triggered_count because we cannot roll back in case an error occurs while decrementing one of the rstc. * Reworded the new call's description. [0] https://lore.kernel.org/lkml/20201001132758.12280-1-aouledameur@xxxxxxxxxxxx drivers/reset/core.c | 73 +++++++++++++++++++++++++++++++++++++++++++ include/linux/reset.h | 1 + 2 files changed, 74 insertions(+) diff --git a/drivers/reset/core.c b/drivers/reset/core.c index a2df88e90011..34e89aa0fb5e 100644 --- a/drivers/reset/core.c +++ b/drivers/reset/core.c @@ -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 diff --git a/include/linux/reset.h b/include/linux/reset.h index 05aa9f440f48..439fec7112a9 100644 --- a/include/linux/reset.h +++ b/include/linux/reset.h @@ -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); -- 2.17.1
