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@xxxxxxxxxxxxxx>
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;
> }
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