Hi Maxime,
On Mon, 2020-02-24 at 10:06 +0100, Maxime Ripard wrote:
> The reset-simple code lacks a reset callback that is still pretty easy to
> implement. The only real thing to consider is the delay needed for a device
> to be reset, so let's expose that as part of the reset-simple driver data.
>
> Cc: Philipp Zabel <p.za...@pengutronix.de>
> Signed-off-by: Maxime Ripard <max...@cerno.tech>
This shoulod be done in such a way that simple reset drivers which do
not set the reset delay continue to return -ENOTSUPP from
reset_control_reset().
> ---
> drivers/reset/reset-simple.c | 21 +++++++++++++++++++++
> include/linux/reset/reset-simple.h | 4 ++++
> 2 files changed, 25 insertions(+)
>
> diff --git a/drivers/reset/reset-simple.c b/drivers/reset/reset-simple.c
> index c854aa351640..7a8c56512ae9 100644
> --- a/drivers/reset/reset-simple.c
> +++ b/drivers/reset/reset-simple.c
> @@ -11,6 +11,7 @@
> * Maxime Ripard <maxime.rip...@free-electrons.com>
> */
>
> +#include <linux/delay.h>
> #include <linux/device.h>
> #include <linux/err.h>
> #include <linux/io.h>
> @@ -63,6 +64,25 @@ static int reset_simple_deassert(struct
> reset_controller_dev *rcdev,
> return reset_simple_update(rcdev, id, false);
> }
>
> +static int reset_simple_reset(struct reset_controller_dev *rcdev,
> + unsigned long id)
> +{
> + struct reset_simple_data *data = to_reset_simple_data(rcdev);
> + int ret;
You could just return -ENOTSUPP here if data->reset_ms == 0.
> + ret = reset_simple_assert(rcdev, id);
> + if (ret)
> + return ret;
> +
> + mdelay(data->reset_ms);
Have you considered specifying the delay in microseconds instead?
That would allow to use usleep_range() for shorter delays.
> + ret = reset_simple_deassert(rcdev, id);
> + if (ret)
> + return ret;
> +
> + return 0;
> +}
> +
> static int reset_simple_status(struct reset_controller_dev *rcdev,
> unsigned long id)
> {
> @@ -80,6 +100,7 @@ static int reset_simple_status(struct reset_controller_dev
> *rcdev,
> const struct reset_control_ops reset_simple_ops = {
> .assert = reset_simple_assert,
> .deassert = reset_simple_deassert,
> + .reset = reset_simple_reset,
> .status = reset_simple_status,
> };
> EXPORT_SYMBOL_GPL(reset_simple_ops);
> diff --git a/include/linux/reset/reset-simple.h
> b/include/linux/reset/reset-simple.h
> index 08ccb25a55e6..a5887f6cbe50 100644
> --- a/include/linux/reset/reset-simple.h
> +++ b/include/linux/reset/reset-simple.h
> @@ -27,6 +27,9 @@
> * @status_active_low: if true, bits read back as cleared while the reset is
> * asserted. Otherwise, bits read back as set while the
> * reset is asserted.
> + * @reset_ms: Minimum delay in milliseconds needed that needs to be
> + * waited for between an assert and a deassert to reset the
> + * device.
If multiple consumers with different delay requirements are connected to
this reset controllers, this must the largest minimum delay. Could you
add mention for this in the comment?
regards
Philipp
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