Re: [PATCH v4 05/27] clk: mediatek: clk-mux: Add ops for mux gates with HW voter and FENC

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

On Tue, Aug 5, 2025 at 10:55 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 |  1 +
>  drivers/clk/mediatek/clk-mux.c | 71 +++++++++++++++++++++++++++++++++-
>  drivers/clk/mediatek/clk-mux.h | 42 ++++++++++++++++++++
>  3 files changed, 113 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/clk/mediatek/clk-mtk.h b/drivers/clk/mediatek/clk-mtk.h
> index 8ed2c9208b1f..e2cefd9bc5b8 100644
> --- a/drivers/clk/mediatek/clk-mtk.h
> +++ b/drivers/clk/mediatek/clk-mtk.h
> @@ -20,6 +20,7 @@
>
>  #define MHZ (1000 * 1000)
>
> +#define MTK_WAIT_HWV_DONE_US   30
>  #define MTK_WAIT_FENC_DONE_US  30
>
>  struct platform_device;
> diff --git a/drivers/clk/mediatek/clk-mux.c b/drivers/clk/mediatek/clk-mux.c
> index b1b8eeb0b501..65889fc6a3e5 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>
> @@ -21,6 +22,7 @@
>  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;
> @@ -118,6 +120,41 @@ 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);
> @@ -189,6 +226,14 @@ 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,
> @@ -216,9 +261,20 @@ 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;
> @@ -234,8 +290,13 @@ 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) {
> +               dev_err(dev, "regmap not found for hardware voter clocks\n");
> +               return ERR_PTR(-ENXIO);
> +       }
>
>         clk_mux->regmap = regmap;
> +       clk_mux->regmap_hwv = regmap_hwv;
>         clk_mux->data = mux;
>         clk_mux->lock = lock;
>         clk_mux->hw.init = &init;
> @@ -268,6 +329,7 @@ int mtk_clk_register_muxes(struct device *dev,
>                            struct clk_hw_onecell_data *clk_data)
>  {
>         struct regmap *regmap;
> +       struct regmap *regmap_hwv;
>         struct clk_hw *hw;
>         int i;
>
> @@ -277,6 +339,13 @@ int mtk_clk_register_muxes(struct device *dev,
>                 return PTR_ERR(regmap);
>         }
>
> +       regmap_hwv = mtk_clk_get_hwv_regmap(node);
> +       if (IS_ERR(regmap_hwv)) {
> +               pr_err("Cannot find hardware voter regmap for %pOF: %pe\n",
> +                      node, regmap_hwv);
> +               return PTR_ERR(regmap_hwv);

Is there a reason why we aren't using dev_err() or even dev_err_probe()
here?

The rest looks OK.

ChenYu

> +       }
> +
>         for (i = 0; i < num; i++) {
>                 const struct mtk_mux *mux = &muxes[i];
>
> @@ -286,7 +355,7 @@ int mtk_clk_register_muxes(struct device *dev,
>                         continue;
>                 }
>
> -               hw = mtk_clk_register_mux(dev, mux, regmap, lock);
> +               hw = mtk_clk_register_mux(dev, mux, regmap, regmap_hwv, lock);
>
>                 if (IS_ERR(hw)) {
>                         pr_err("Failed to register clk %s: %pe\n", mux->name,
> diff --git a/drivers/clk/mediatek/clk-mux.h b/drivers/clk/mediatek/clk-mux.h
> index c65cfb7f8fc3..fb6f7951379c 100644
> --- a/drivers/clk/mediatek/clk-mux.h
> +++ b/drivers/clk/mediatek/clk-mux.h
> @@ -28,6 +28,10 @@ struct mtk_mux {
>         u32 set_ofs;
>         u32 clr_ofs;
>         u32 upd_ofs;
> +
> +       u32 hwv_set_ofs;
> +       u32 hwv_clr_ofs;
> +       u32 hwv_sta_ofs;
>         u32 fenc_sta_mon_ofs;
>
>         u8 mux_shift;
> @@ -80,6 +84,7 @@ struct mtk_mux {
>  extern const struct clk_ops mtk_mux_clr_set_upd_ops;
>  extern const struct clk_ops mtk_mux_gate_clr_set_upd_ops;
>  extern const struct clk_ops mtk_mux_gate_fenc_clr_set_upd_ops;
> +extern const struct clk_ops mtk_mux_gate_hwv_fenc_clr_set_upd_ops;
>
>  #define MUX_GATE_CLR_SET_UPD_FLAGS(_id, _name, _parents, _mux_ofs,     \
>                         _mux_set_ofs, _mux_clr_ofs, _shift, _width,     \
> @@ -121,6 +126,43 @@ extern const struct clk_ops mtk_mux_gate_fenc_clr_set_upd_ops;
>                         0, _upd_ofs, _upd, CLK_SET_RATE_PARENT,         \
>                         mtk_mux_clr_set_upd_ops)
>
> +#define MUX_GATE_HWV_FENC_CLR_SET_UPD_FLAGS(_id, _name, _parents,                      \
> +                               _mux_ofs, _mux_set_ofs, _mux_clr_ofs,                   \
> +                               _hwv_sta_ofs, _hwv_set_ofs, _hwv_clr_ofs,               \
> +                               _shift, _width, _gate, _upd_ofs, _upd,                  \
> +                               _fenc_sta_mon_ofs, _fenc, _flags) {                     \
> +                       .id = _id,                                                      \
> +                       .name = _name,                                                  \
> +                       .mux_ofs = _mux_ofs,                                            \
> +                       .set_ofs = _mux_set_ofs,                                        \
> +                       .clr_ofs = _mux_clr_ofs,                                        \
> +                       .hwv_sta_ofs = _hwv_sta_ofs,                                    \
> +                       .hwv_set_ofs = _hwv_set_ofs,                                    \
> +                       .hwv_clr_ofs = _hwv_clr_ofs,                                    \
> +                       .upd_ofs = _upd_ofs,                                            \
> +                       .fenc_sta_mon_ofs = _fenc_sta_mon_ofs,                          \
> +                       .mux_shift = _shift,                                            \
> +                       .mux_width = _width,                                            \
> +                       .gate_shift = _gate,                                            \
> +                       .upd_shift = _upd,                                              \
> +                       .fenc_shift = _fenc,                                            \
> +                       .parent_names = _parents,                                       \
> +                       .num_parents = ARRAY_SIZE(_parents),                            \
> +                       .flags =  _flags,                                               \
> +                       .ops = &mtk_mux_gate_hwv_fenc_clr_set_upd_ops,                  \
> +               }
> +
> +#define MUX_GATE_HWV_FENC_CLR_SET_UPD(_id, _name, _parents,                            \
> +                               _mux_ofs, _mux_set_ofs, _mux_clr_ofs,                   \
> +                               _hwv_sta_ofs, _hwv_set_ofs, _hwv_clr_ofs,               \
> +                               _shift, _width, _gate, _upd_ofs, _upd,                  \
> +                               _fenc_sta_mon_ofs, _fenc)                               \
> +                       MUX_GATE_HWV_FENC_CLR_SET_UPD_FLAGS(_id, _name, _parents,       \
> +                               _mux_ofs, _mux_set_ofs, _mux_clr_ofs,                   \
> +                               _hwv_sta_ofs, _hwv_set_ofs, _hwv_clr_ofs,               \
> +                               _shift, _width, _gate, _upd_ofs, _upd,                  \
> +                               _fenc_sta_mon_ofs, _fenc, 0)
> +
>  #define MUX_GATE_FENC_CLR_SET_UPD_FLAGS(_id, _name, _parents, _paridx,         \
>                         _num_parents, _mux_ofs, _mux_set_ofs, _mux_clr_ofs,     \
>                         _shift, _width, _gate, _upd_ofs, _upd,                  \
> --
> 2.39.5
>