Re: [PATCH v2 07/23] clk: mediatek: clk-mtk: Add dummy clock ops

Chen-Yu Tsai
2022-12-30T05:19:45Z

On Fri, Dec 23, 2022 at 5:43 PM AngeloGioacchino Del Regno
<angelogioacchino.delregno@collabora.com> wrote:
>
> In order to migrate some (few) old clock drivers to the common
> mtk_clk_simple_probe() function, add dummy clock ops to be able
> to insert a dummy clock with ID 0 at the beginning of the list.
>
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> ---
> drivers/clk/mediatek/clk-mtk.c | 15 +++++++++++++++
> drivers/clk/mediatek/clk-mtk.h | 19 +++++++++++++++++++
> 2 files changed, 34 insertions(+)
>
> diff --git a/drivers/clk/mediatek/clk-mtk.c b/drivers/clk/mediatek/clk-mtk.c
> index a1ab34305b95..d05364e17e95 100644
> --- a/drivers/clk/mediatek/clk-mtk.c
> +++ b/drivers/clk/mediatek/clk-mtk.c
> @@ -18,6 +18,21 @@
> #include "clk-mtk.h"
> #include "clk-gate.h"
>
> +const struct mtk_gate_regs cg_regs_dummy = { 0, 0, 0 };

You could probably just use an empty { }, since the contents don't matter.
It would make any possible future changes to |struct mtk_gate_regs| touch
one less place.

Otherwise,

Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>

> +
> +static int mtk_clk_dummy_enable(struct clk_hw *hw)
> +{
> + return 0;
> +}
> +
> +static void mtk_clk_dummy_disable(struct clk_hw *hw) { }
> +
> +const struct clk_ops mtk_clk_dummy_ops = {
> + .enable = mtk_clk_dummy_enable,
> + .disable = mtk_clk_dummy_disable,
> +};
> +EXPORT_SYMBOL_GPL(mtk_clk_dummy_ops);
> +
> static void mtk_init_clk_data(struct clk_hw_onecell_data *clk_data,
> unsigned int clk_num)
> {
> diff --git a/drivers/clk/mediatek/clk-mtk.h b/drivers/clk/mediatek/clk-mtk.h
> index 15122504c02d..dd43235285db 100644
> --- a/drivers/clk/mediatek/clk-mtk.h
> +++ b/drivers/clk/mediatek/clk-mtk.h
> @@ -22,6 +22,25 @@
>
> struct platform_device;
>
> +/*
> + * We need the clock IDs to start from zero but to maintain devicetree
> + * backwards compatibility we can't change bindings to start from zero.
> + * Only a few platforms are affected, so we solve issues given by the
> + * commonized MTK clocks probe function(s) by adding a dummy clock at
> + * the beginning where needed.
> + */
> +#define CLK_DUMMY 0
> +
> +extern const struct clk_ops mtk_clk_dummy_ops;
> +extern const struct mtk_gate_regs cg_regs_dummy;
> +
> +#define GATE_DUMMY(_id, _name) { \
> + .id = _id, \
> + .name = _name, \
> + .regs = &cg_regs_dummy, \
> + .ops = &mtk_clk_dummy_ops, \
> + }
> +
> struct mtk_fixed_clk {
> int id;
> const char *name;
> --
> 2.39.0
>