Re: [PATCH v1 01/10] clk: qcom: clk-alpha-pll: introduce stromer plus ops

[Varadarajan Narayanan <quic_varada@quicinc.com>]

On Thu, Sep 07, 2023 at 04:39:33PM +0300, Dmitry Baryshkov wrote:
> On Thu, 7 Sept 2023 at 08:22, Varadarajan Narayanan
> <quic_varada@quicinc.com> wrote:
> >
> > Stromer plus APSS PLL does not support dynamic frequency scaling.
> > To switch between frequencies, we have to shut down the PLL,
> > configure the L and ALPHA values and turn on again. So introduce the
> > separate set of ops for Stromer Plus PLL.
> >
> > Signed-off-by: Kathiravan T <quic_kathirav@quicinc.com>
> > Signed-off-by: Varadarajan Narayanan <quic_varada@quicinc.com>
> > ---
> >  drivers/clk/qcom/clk-alpha-pll.c | 68 ++++++++++++++++++++++++++++++++++++++++
> >  drivers/clk/qcom/clk-alpha-pll.h |  1 +
> >  2 files changed, 69 insertions(+)
> >
> > diff --git a/drivers/clk/qcom/clk-alpha-pll.c b/drivers/clk/qcom/clk-alpha-pll.c
> > index e4ef645..2ef81f7 100644
> > --- a/drivers/clk/qcom/clk-alpha-pll.c
> > +++ b/drivers/clk/qcom/clk-alpha-pll.c
> > @@ -2479,3 +2479,71 @@ const struct clk_ops clk_alpha_pll_stromer_ops = {
> >         .set_rate = clk_alpha_pll_stromer_set_rate,
> >  };
> >  EXPORT_SYMBOL_GPL(clk_alpha_pll_stromer_ops);
> > +
> > +static int clk_alpha_pll_stromer_plus_determine_rate(struct clk_hw *hw,
> > +                                                    struct clk_rate_request *req)
> > +{
> > +       struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
> > +       u32 l, alpha_width = pll_alpha_width(pll);
> > +       u64 a;
> > +
> > +       req->rate = alpha_pll_round_rate(req->rate, req->best_parent_rate, &l,
> > +                                        &a, alpha_width);
> > +       return 0;
> > +}
>
> What is the plL_alpha_width on stromer_plus? Does
> clk_alpha_pll_stromer_determine_rate() work for you?

pll_alpha_width is 4. I tested with clk_alpha_pll_stromer_determine_rate()
and it works. Will change and post a new version.

Thanks
Varada

> > +
> > +static int clk_alpha_pll_stromer_plus_set_rate(struct clk_hw *hw,
> > +                                              unsigned long rate,
> > +                                              unsigned long prate)
> > +{
> > +       struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
> > +       u32 l, alpha_width = pll_alpha_width(pll);
> > +       int ret;
> > +       u64 a;
> > +
> > +       rate = alpha_pll_round_rate(rate, prate, &l, &a, alpha_width);
> > +
> > +       regmap_write(pll->clkr.regmap, PLL_MODE(pll), 0);
> > +
> > +       /* Delay of 2 output clock ticks required until output is disabled */
> > +       udelay(1);
> > +
> > +       regmap_write(pll->clkr.regmap, PLL_L_VAL(pll), l);
> > +
> > +       if (alpha_width > ALPHA_BITWIDTH)
> > +               a <<= alpha_width - ALPHA_BITWIDTH;
> > +
> > +       regmap_write(pll->clkr.regmap, PLL_ALPHA_VAL(pll), a);
> > +       regmap_write(pll->clkr.regmap, PLL_ALPHA_VAL_U(pll),
> > +                                       a >> ALPHA_BITWIDTH);
> > +
> > +       regmap_write(pll->clkr.regmap, PLL_MODE(pll), PLL_BYPASSNL);
> > +
> > +       /* Wait five micro seconds or more */
> > +       udelay(5);
> > +       regmap_update_bits(pll->clkr.regmap, PLL_MODE(pll), PLL_RESET_N,
> > +                          PLL_RESET_N);
> > +
> > +       /* The lock time should be less than 50 micro seconds worst case */
> > +       udelay(50);
> > +
> > +       ret = wait_for_pll_enable_lock(pll);
> > +       if (ret) {
> > +               pr_err("alpha pll running in 800 MHz with source GPLL0\n");
> > +               return ret;
> > +       }
> > +       regmap_update_bits(pll->clkr.regmap, PLL_MODE(pll), PLL_OUTCTRL,
> > +                          PLL_OUTCTRL);
> > +
> > +       return 0;
> > +}
> > +
> > +const struct clk_ops clk_alpha_pll_stromer_plus_ops = {
> > +       .enable = clk_alpha_pll_enable,
> > +       .disable = clk_alpha_pll_disable,
> > +       .is_enabled = clk_alpha_pll_is_enabled,
> > +       .recalc_rate = clk_alpha_pll_recalc_rate,
> > +       .determine_rate = clk_alpha_pll_stromer_plus_determine_rate,
> > +       .set_rate = clk_alpha_pll_stromer_plus_set_rate,
> > +};
> > +EXPORT_SYMBOL_GPL(clk_alpha_pll_stromer_plus_ops);
> > diff --git a/drivers/clk/qcom/clk-alpha-pll.h b/drivers/clk/qcom/clk-alpha-pll.h
> > index e4bd863..903fbab 100644
> > --- a/drivers/clk/qcom/clk-alpha-pll.h
> > +++ b/drivers/clk/qcom/clk-alpha-pll.h
> > @@ -152,6 +152,7 @@ extern const struct clk_ops clk_alpha_pll_postdiv_ops;
> >  extern const struct clk_ops clk_alpha_pll_huayra_ops;
> >  extern const struct clk_ops clk_alpha_pll_postdiv_ro_ops;
> >  extern const struct clk_ops clk_alpha_pll_stromer_ops;
> > +extern const struct clk_ops clk_alpha_pll_stromer_plus_ops;
> >
> >  extern const struct clk_ops clk_alpha_pll_fabia_ops;
> >  extern const struct clk_ops clk_alpha_pll_fixed_fabia_ops;
> > --
> > 2.7.4
> >
>
>
> --
> With best wishes
> Dmitry