diff options
| -rw-r--r-- | drivers/reset/core.c | 43 |
1 files changed, 37 insertions, 6 deletions
diff --git a/drivers/reset/core.c b/drivers/reset/core.c index b8ae1dbd4c17..10368ed8fd13 100644 --- a/drivers/reset/core.c +++ b/drivers/reset/core.c @@ -32,6 +32,9 @@ static LIST_HEAD(reset_controller_list); * @refcnt: Number of gets of this reset_control * @shared: Is this a shared (1), or an exclusive (0) reset_control? * @deassert_cnt: Number of times this reset line has been deasserted + * @triggered_count: Number of times this reset line has been reset. Currently + * only used for shared resets, which means that the value + * will be either 0 or 1. */ struct reset_control { struct reset_controller_dev *rcdev; @@ -40,6 +43,7 @@ struct reset_control { unsigned int refcnt; int shared; atomic_t deassert_count; + atomic_t triggered_count; }; /** @@ -134,18 +138,35 @@ EXPORT_SYMBOL_GPL(devm_reset_controller_register); * reset_control_reset - reset the controlled device * @rstc: reset controller * - * Calling this on a shared reset controller is an error. + * On a shared reset line the actual reset pulse is only triggered once for the + * lifetime of the reset_control instance: for all but the first caller this is + * a no-op. + * Consumers must not use reset_control_(de)assert on shared reset lines when + * reset_control_reset has been used. */ int reset_control_reset(struct reset_control *rstc) { - if (WARN_ON(IS_ERR_OR_NULL(rstc)) || - WARN_ON(rstc->shared)) + int ret; + + if (WARN_ON(IS_ERR_OR_NULL(rstc))) return -EINVAL; - if (rstc->rcdev->ops->reset) - return rstc->rcdev->ops->reset(rstc->rcdev, rstc->id); + if (!rstc->rcdev->ops->reset) + return -ENOTSUPP; - return -ENOTSUPP; + if (rstc->shared) { + if (WARN_ON(atomic_read(&rstc->deassert_count) != 0)) + return -EINVAL; + + if (atomic_inc_return(&rstc->triggered_count) != 1) + return 0; + } + + ret = rstc->rcdev->ops->reset(rstc->rcdev, rstc->id); + if (rstc->shared && !ret) + atomic_dec(&rstc->triggered_count); + + return ret; } EXPORT_SYMBOL_GPL(reset_control_reset); @@ -159,6 +180,8 @@ EXPORT_SYMBOL_GPL(reset_control_reset); * * For shared reset controls a driver cannot expect the hw's registers and * internal state to be reset, but must be prepared for this to happen. + * Consumers must not use reset_control_reset on shared reset lines when + * reset_control_(de)assert has been used. */ int reset_control_assert(struct reset_control *rstc) { @@ -169,6 +192,9 @@ int reset_control_assert(struct reset_control *rstc) return -ENOTSUPP; if (rstc->shared) { + if (WARN_ON(atomic_read(&rstc->triggered_count) != 0)) + return -EINVAL; + if (WARN_ON(atomic_read(&rstc->deassert_count) == 0)) return -EINVAL; @@ -185,6 +211,8 @@ EXPORT_SYMBOL_GPL(reset_control_assert); * @rstc: reset controller * * After calling this function, the reset is guaranteed to be deasserted. + * Consumers must not use reset_control_reset on shared reset lines when + * reset_control_(de)assert has been used. */ int reset_control_deassert(struct reset_control *rstc) { @@ -195,6 +223,9 @@ int reset_control_deassert(struct reset_control *rstc) return -ENOTSUPP; if (rstc->shared) { + if (WARN_ON(atomic_read(&rstc->triggered_count) != 0)) + return -EINVAL; + if (atomic_inc_return(&rstc->deassert_count) != 1) return 0; } |