Re: [PATCH v5 05/27] clk: mediatek: clk-mux: Add ops for mux gates with HW voter and FENC

[Chen-Yu Tsai <wenst@chromium.org>]

On Fri, Aug 29, 2025 at 5:21 PM Laura Nao <laura.nao@collabora.com> wrote:
>
> MT8196 use a HW voter for mux gate enable/disable control, along with a
> FENC status bit to check the status. Voting is performed using
> set/clr/upd registers, with a status bit used to verify the vote state.
> Add new set of mux gate clock operations with support for voting via
> set/clr/upd regs and FENC status logic.
>
> Reviewed-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> Signed-off-by: Laura Nao <laura.nao@collabora.com>
> ---
>  drivers/clk/mediatek/clk-mtk.h |  2 +
>  drivers/clk/mediatek/clk-mux.c | 73 +++++++++++++++++++++++++++++++++-
>  drivers/clk/mediatek/clk-mux.h | 42 +++++++++++++++++++
>  3 files changed, 116 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/clk/mediatek/clk-mtk.h b/drivers/clk/mediatek/clk-mtk.h
> index 11962fac43ea..c381d6a6d908 100644
> --- a/drivers/clk/mediatek/clk-mtk.h
> +++ b/drivers/clk/mediatek/clk-mtk.h
> @@ -20,6 +20,8 @@
>
>  #define MHZ (1000 * 1000)
>
> +#define MTK_WAIT_HWV_DONE_US   30
> +
>  struct platform_device;
>
>  /*
> diff --git a/drivers/clk/mediatek/clk-mux.c b/drivers/clk/mediatek/clk-mux.c
> index 3931d157b262..2c2679e158e7 100644
> --- a/drivers/clk/mediatek/clk-mux.c
> +++ b/drivers/clk/mediatek/clk-mux.c
> @@ -8,6 +8,7 @@
>  #include <linux/clk-provider.h>
>  #include <linux/compiler_types.h>
>  #include <linux/container_of.h>
> +#include <linux/dev_printk.h>
>  #include <linux/err.h>
>  #include <linux/mfd/syscon.h>
>  #include <linux/module.h>
> @@ -15,6 +16,7 @@
>  #include <linux/spinlock.h>
>  #include <linux/slab.h>
>
> +#include "clk-mtk.h"
>  #include "clk-mux.h"
>
>  #define MTK_WAIT_FENC_DONE_US  30
> @@ -22,6 +24,7 @@
>  struct mtk_clk_mux {
>         struct clk_hw hw;
>         struct regmap *regmap;
> +       struct regmap *regmap_hwv;
>         const struct mtk_mux *data;
>         spinlock_t *lock;
>         bool reparent;
> @@ -119,6 +122,41 @@ static int mtk_clk_mux_is_enabled(struct clk_hw *hw)
>         return (val & BIT(mux->data->gate_shift)) == 0;
>  }
>
> +static int mtk_clk_mux_hwv_fenc_enable(struct clk_hw *hw)
> +{
> +       struct mtk_clk_mux *mux = to_mtk_clk_mux(hw);
> +       u32 val;
> +       int ret;
> +
> +       regmap_write(mux->regmap_hwv, mux->data->hwv_set_ofs,
> +                    BIT(mux->data->gate_shift));
> +
> +       ret = regmap_read_poll_timeout_atomic(mux->regmap_hwv, mux->data->hwv_sta_ofs,
> +                                             val, val & BIT(mux->data->gate_shift), 0,
> +                                             MTK_WAIT_HWV_DONE_US);
> +       if (ret)
> +               return ret;
> +
> +       ret = regmap_read_poll_timeout_atomic(mux->regmap, mux->data->fenc_sta_mon_ofs,
> +                                             val, val & BIT(mux->data->fenc_shift), 1,
> +                                             MTK_WAIT_FENC_DONE_US);
> +
> +       return ret;
> +}
> +
> +static void mtk_clk_mux_hwv_disable(struct clk_hw *hw)
> +{
> +       struct mtk_clk_mux *mux = to_mtk_clk_mux(hw);
> +       u32 val;
> +
> +       regmap_write(mux->regmap_hwv, mux->data->hwv_clr_ofs,
> +                    BIT(mux->data->gate_shift));
> +
> +       regmap_read_poll_timeout_atomic(mux->regmap_hwv, mux->data->hwv_sta_ofs,
> +                                       val, (val & BIT(mux->data->gate_shift)),
> +                                       0, MTK_WAIT_HWV_DONE_US);
> +}
> +
>  static u8 mtk_clk_mux_get_parent(struct clk_hw *hw)
>  {
>         struct mtk_clk_mux *mux = to_mtk_clk_mux(hw);
> @@ -190,6 +228,14 @@ static int mtk_clk_mux_determine_rate(struct clk_hw *hw,
>         return clk_mux_determine_rate_flags(hw, req, mux->data->flags);
>  }
>
> +static bool mtk_clk_mux_uses_hwv(const struct clk_ops *ops)
> +{
> +       if (ops == &mtk_mux_gate_hwv_fenc_clr_set_upd_ops)
> +               return true;
> +
> +       return false;
> +}
> +
>  const struct clk_ops mtk_mux_clr_set_upd_ops = {
>         .get_parent = mtk_clk_mux_get_parent,
>         .set_parent = mtk_clk_mux_set_parent_setclr_lock,
> @@ -217,9 +263,20 @@ const struct clk_ops mtk_mux_gate_fenc_clr_set_upd_ops = {
>  };
>  EXPORT_SYMBOL_GPL(mtk_mux_gate_fenc_clr_set_upd_ops);
>
> +const struct clk_ops mtk_mux_gate_hwv_fenc_clr_set_upd_ops = {
> +       .enable = mtk_clk_mux_hwv_fenc_enable,
> +       .disable = mtk_clk_mux_hwv_disable,
> +       .is_enabled = mtk_clk_mux_fenc_is_enabled,
> +       .get_parent = mtk_clk_mux_get_parent,
> +       .set_parent = mtk_clk_mux_set_parent_setclr_lock,
> +       .determine_rate = mtk_clk_mux_determine_rate,
> +};
> +EXPORT_SYMBOL_GPL(mtk_mux_gate_hwv_fenc_clr_set_upd_ops);
> +
>  static struct clk_hw *mtk_clk_register_mux(struct device *dev,
>                                            const struct mtk_mux *mux,
>                                            struct regmap *regmap,
> +                                          struct regmap *regmap_hwv,
>                                            spinlock_t *lock)
>  {
>         struct mtk_clk_mux *clk_mux;
> @@ -235,8 +292,14 @@ static struct clk_hw *mtk_clk_register_mux(struct device *dev,
>         init.parent_names = mux->parent_names;
>         init.num_parents = mux->num_parents;
>         init.ops = mux->ops;
> +       if (mtk_clk_mux_uses_hwv(init.ops) && !regmap_hwv) {
> +               return dev_err_ptr_probe(
> +                       dev, -ENXIO,
> +                       "regmap not found for hardware voter clocks\n");
> +       }

Nit: The braces aren't really needed. But no need to respin just for this.

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