Re: [PATCH v2 2/5] clk: scmi: Add support for state control restricted clocks

[Stephen Boyd <sboyd@kernel.org>]

Quoting Cristian Marussi (2024-03-25 14:00:22)
> Some exposed SCMI Clocks could be marked as non-supporting state changes.
> Configure a clk_ops descriptor which does not provide the state change
> callbacks for such clocks when registering with CLK framework.
> 
> CC: Michael Turquette <mturquette@baylibre.com>
> CC: Stephen Boyd <sboyd@kernel.org>
> CC: linux-clk@vger.kernel.org
> Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
> ---
>  drivers/clk/clk-scmi.c | 22 +++++++++++++++-------
>  1 file changed, 15 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/clk/clk-scmi.c b/drivers/clk/clk-scmi.c
> index d5d369b052bd..fc9603988d91 100644
> --- a/drivers/clk/clk-scmi.c
> +++ b/drivers/clk/clk-scmi.c
> @@ -18,6 +18,7 @@
>  
>  enum scmi_clk_feats {
>         SCMI_CLK_ATOMIC_SUPPORTED,
> +       SCMI_CLK_STATE_CTRL_FORBIDDEN,

Can it be positive, i.e. SCMI_CLK_STATE_CTRL_SUPPORTED?

>         SCMI_CLK_MAX_FEATS
>  };
>  
> @@ -230,15 +231,19 @@ scmi_clk_ops_alloc(struct device *dev, unsigned long feats_key)
>          * only the prepare/unprepare API, as allowed by the clock framework
>          * when atomic calls are not available.
>          */
> -       if (feats_key & BIT(SCMI_CLK_ATOMIC_SUPPORTED)) {
> -               ops->enable = scmi_clk_atomic_enable;
> -               ops->disable = scmi_clk_atomic_disable;
> -               ops->is_enabled = scmi_clk_atomic_is_enabled;
> -       } else {
> -               ops->prepare = scmi_clk_enable;
> -               ops->unprepare = scmi_clk_disable;
> +       if (!(feats_key & BIT(SCMI_CLK_STATE_CTRL_FORBIDDEN))) {
> +               if (feats_key & BIT(SCMI_CLK_ATOMIC_SUPPORTED)) {
> +                       ops->enable = scmi_clk_atomic_enable;
> +                       ops->disable = scmi_clk_atomic_disable;
> +               } else {
> +                       ops->prepare = scmi_clk_enable;
> +                       ops->unprepare = scmi_clk_disable;
> +               }
>         }
>  
> +       if (feats_key & BIT(SCMI_CLK_ATOMIC_SUPPORTED))
> +               ops->is_enabled = scmi_clk_atomic_is_enabled;
> +
>         /* Rate ops */
>         ops->recalc_rate = scmi_clk_recalc_rate;
>         ops->round_rate = scmi_clk_round_rate;
> @@ -288,6 +293,9 @@ scmi_clk_ops_select(struct scmi_clk *sclk, bool atomic_capable,
>         if (atomic_capable && ci->enable_latency <= atomic_threshold)
>                 feats_key |= BIT(SCMI_CLK_ATOMIC_SUPPORTED);
>  
> +       if (ci->state_ctrl_forbidden)

Then this is negated.

> +               feats_key |= BIT(SCMI_CLK_STATE_CTRL_FORBIDDEN);
> +
>         /* Lookup previously allocated ops */
>         ops = clk_ops_db[feats_key];