On Wed 23 Mar 03:50 CDT 2022, Dmitry Baryshkov wrote:
> On recent Qualcomm platforms the QMP PIPE clocks feed into a set of
> muxes which must be parked to the "safe" source (bi_tcxo) when
> corresponding GDSC is turned off and on again. Currently this is
> handcoded in the PCIe driver by reparenting the gcc_pipe_N_clk_src
> clock. However the same code sequence should be applied in the
> pcie-qcom endpoint, USB3 and UFS drivers.
>
> Rather than copying this sequence over and over again, follow the
> example of clk_rcg2_shared_ops and implement this parking in the
> enable() and disable() clock operations. As we are changing the parent
> behind the back of the clock framework, also implement custom
> set_parent() and get_parent() operations behaving accroding to the clock
> framework expectations (cache the new parent if the clock is in disabled
> state, return cached parent).
>
Reviewed-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> ---
> drivers/clk/qcom/clk-regmap-mux.c | 78 +++++++++++++++++++++++++++++++
> drivers/clk/qcom/clk-regmap-mux.h | 3 ++
> 2 files changed, 81 insertions(+)
>
> diff --git a/drivers/clk/qcom/clk-regmap-mux.c b/drivers/clk/qcom/clk-regmap-mux.c
> index 45d9cca28064..c39ee783ee83 100644
> --- a/drivers/clk/qcom/clk-regmap-mux.c
> +++ b/drivers/clk/qcom/clk-regmap-mux.c
> @@ -49,9 +49,87 @@ static int mux_set_parent(struct clk_hw *hw, u8 index)
> return regmap_update_bits(clkr->regmap, mux->reg, mask, val);
> }
>
> +static u8 mux_safe_get_parent(struct clk_hw *hw)
> +{
> + struct clk_regmap_mux *mux = to_clk_regmap_mux(hw);
> + unsigned int val;
> +
> + if (clk_hw_is_enabled(hw))
> + return mux_get_parent(hw);
> +
> + val = mux->stored_parent_cfg;
> +
> + if (mux->parent_map)
> + return qcom_find_cfg_index(hw, mux->parent_map, val);
> +
> + return val;
> +}
> +
> +static int mux_safe_set_parent(struct clk_hw *hw, u8 index)
> +{
> + struct clk_regmap_mux *mux = to_clk_regmap_mux(hw);
> +
> + if (clk_hw_is_enabled(hw))
> + return mux_set_parent(hw, index);
> +
> + if (mux->parent_map)
> + index = mux->parent_map[index].cfg;
> +
> + mux->stored_parent_cfg = index;
> +
> + return 0;
> +}
> +
> +static void mux_safe_disable(struct clk_hw *hw)
> +{
> + struct clk_regmap_mux *mux = to_clk_regmap_mux(hw);
> + struct clk_regmap *clkr = to_clk_regmap(hw);
> + unsigned int mask = GENMASK(mux->width + mux->shift - 1, mux->shift);
> + unsigned int val;
> +
> + regmap_read(clkr->regmap, mux->reg, &val);
> +
> + mux->stored_parent_cfg = (val & mask) >> mux->shift;
> +
> + val = mux->safe_src_parent;
> + if (mux->parent_map) {
> + int index = qcom_find_src_index(hw, mux->parent_map, val);
> +
> + if (WARN_ON(index < 0))
> + return;
> +
> + val = mux->parent_map[index].cfg;
> + }
> + val <<= mux->shift;
> +
> + regmap_update_bits(clkr->regmap, mux->reg, mask, val);
> +}
> +
> +static int mux_safe_enable(struct clk_hw *hw)
> +{
> + struct clk_regmap_mux *mux = to_clk_regmap_mux(hw);
> + struct clk_regmap *clkr = to_clk_regmap(hw);
> + unsigned int mask = GENMASK(mux->width + mux->shift - 1, mux->shift);
> + unsigned int val;
> +
> + val = mux->stored_parent_cfg;
> + val <<= mux->shift;
> +
> + return regmap_update_bits(clkr->regmap, mux->reg, mask, val);
> +}
> +
> const struct clk_ops clk_regmap_mux_closest_ops = {
> .get_parent = mux_get_parent,
> .set_parent = mux_set_parent,
> .determine_rate = __clk_mux_determine_rate_closest,
> };
> EXPORT_SYMBOL_GPL(clk_regmap_mux_closest_ops);
> +
> +const struct clk_ops clk_regmap_mux_safe_ops = {
> + .enable = mux_safe_enable,
> + .disable = mux_safe_disable,
> + .get_parent = mux_safe_get_parent,
> + .set_parent = mux_safe_set_parent,
> + .determine_rate = __clk_mux_determine_rate_closest,
> +};
> +EXPORT_SYMBOL_GPL(clk_regmap_mux_safe_ops);
> diff --git a/drivers/clk/qcom/clk-regmap-mux.h b/drivers/clk/qcom/clk-regmap-mux.h
> index db6f4cdd9586..f86c674ce139 100644
> --- a/drivers/clk/qcom/clk-regmap-mux.h
> +++ b/drivers/clk/qcom/clk-regmap-mux.h
> @@ -14,10 +14,13 @@ struct clk_regmap_mux {
> u32 reg;
> u32 shift;
> u32 width;
> + u8 safe_src_parent;
> + u8 stored_parent_cfg;
> const struct parent_map *parent_map;
> struct clk_regmap clkr;
> };
>
> extern const struct clk_ops clk_regmap_mux_closest_ops;
> +extern const struct clk_ops clk_regmap_mux_safe_ops;
>
> #endif
> --
> 2.35.1
>
