| Message ID | 20161112131305.26088-2-martin.blumenstingl@googlemail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
Hi Martin, Am Samstag, den 12.11.2016, 14:13 +0100 schrieb Martin Blumenstingl: > Some SoCs (for example Amlogic GXBB) implement a reset controller which > only supports a reset pulse (triggered via reset_control_reset). At the > same time multiple devices (in case of the Amlogic GXBB SoC both USB > PHYs) are sharing the same reset line. > > This patch allows using reset_control_reset also for shared resets. > There are limitations though: > reset_control_reset can only be used if reset_control_assert was not > used yet. > reset_control_assert can only be used if reset_control_reset was not > used yet. > For shared resets the reset is only triggered once for the lifetime of > the reset_control instance (the reset can be triggered again if all > consumers of that specific reset_control are gone, as the reset > framework will free the reset_control instance in that case). > > Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com> Looks good to me, I've applied it to the reset/next branch. thanks Philipp > --- > drivers/reset/core.c | 43 +++++++++++++++++++++++++++++++++++++------ > 1 file changed, 37 insertions(+), 6 deletions(-) > > diff --git a/drivers/reset/core.c b/drivers/reset/core.c > index b8ae1db..10368ed 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; > }
diff --git a/drivers/reset/core.c b/drivers/reset/core.c index b8ae1db..10368ed 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; }
Some SoCs (for example Amlogic GXBB) implement a reset controller which only supports a reset pulse (triggered via reset_control_reset). At the same time multiple devices (in case of the Amlogic GXBB SoC both USB PHYs) are sharing the same reset line. This patch allows using reset_control_reset also for shared resets. There are limitations though: reset_control_reset can only be used if reset_control_assert was not used yet. reset_control_assert can only be used if reset_control_reset was not used yet. For shared resets the reset is only triggered once for the lifetime of the reset_control instance (the reset can be triggered again if all consumers of that specific reset_control are gone, as the reset framework will free the reset_control instance in that case). Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com> --- drivers/reset/core.c | 43 +++++++++++++++++++++++++++++++++++++------ 1 file changed, 37 insertions(+), 6 deletions(-)