Re: [PATCH v2 3/7] phy: qcom: qmp-pcie: register second optional PHY AUX clock

[Dmitry Baryshkov]

On Fri, 22 Mar 2024 at 11:43, Neil Armstrong <neil.armstrong@xxxxxxxxxx> wrote:
>
> The PCIe Gen4x2 PHY found in the SM8[456]50 SoCs have a second clock,
> add the code to register it for PHYs configs that sets a aux_clock_rate.
>
> In order to get the right clock, add qmp_pcie_clk_hw_get() which uses
> the newly introduced QMP_PCIE_PIPE_CLK & QMP_PCIE_PHY_AUX_CLK clock
> IDs and also supports the legacy bindings by returning the PIPE clock
> when #clock-cells=0.
>
> Signed-off-by: Neil Armstrong <neil.armstrong@xxxxxxxxxx>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>

Small question below.

> ---
>  drivers/phy/qualcomm/phy-qcom-qmp-pcie.c | 78 ++++++++++++++++++++++++++++++--
>  1 file changed, 75 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
> index e8da2e9146dc..6c9a95e62429 100644
> --- a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
> +++ b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
> @@ -22,6 +22,8 @@
>  #include <linux/reset.h>
>  #include <linux/slab.h>
>
> +#include <dt-bindings/phy/phy-qcom-qmp.h>
> +
>  #include "phy-qcom-qmp-common.h"
>
>  #include "phy-qcom-qmp.h"
> @@ -2389,6 +2391,9 @@ struct qmp_phy_cfg {
>
>         /* QMP PHY pipe clock interface rate */
>         unsigned long pipe_clock_rate;
> +
> +       /* QMP PHY AUX clock interface rate */
> +       unsigned long aux_clock_rate;
>  };
>
>  struct qmp_pcie {
> @@ -2420,6 +2425,7 @@ struct qmp_pcie {
>         int mode;
>
>         struct clk_fixed_rate pipe_clk_fixed;
> +       struct clk_fixed_rate aux_clk_fixed;
>  };
>
>  static inline void qphy_setbits(void __iomem *base, u32 offset, u32 val)
> @@ -3686,6 +3692,62 @@ static int phy_pipe_clk_register(struct qmp_pcie *qmp, struct device_node *np)
>         return devm_clk_hw_register(qmp->dev, &fixed->hw);
>  }
>
> +/*
> + * Register a fixed rate PHY aux clock.
> + *
> + * The <s>_phy_aux_clksrc generated by PHY goes to the GCC that gate
> + * controls it. The <s>_phy_aux_clk coming out of the GCC is requested
> + * by the PHY driver for its operations.
> + * We register the <s>_phy_aux_clksrc here. The gcc driver takes care
> + * of assigning this <s>_phy_aux_clksrc as parent to <s>_phy_aux_clk.
> + * Below picture shows this relationship.
> + *
> + *         +---------------+
> + *         |   PHY block   |<<---------------------------------------------+
> + *         |               |                                               |
> + *         |   +-------+   |                      +-----+                  |
> + *   I/P---^-->|  PLL  |---^--->phy_aux_clksrc--->| GCC |--->phy_aux_clk---+
> + *    clk  |   +-------+   |                      +-----+
> + *         +---------------+
> + */
> +static int phy_aux_clk_register(struct qmp_pcie *qmp, struct device_node *np)
> +{
> +       struct clk_fixed_rate *fixed = &qmp->aux_clk_fixed;
> +       struct clk_init_data init = { };
> +       int ret;
> +
> +       ret = of_property_read_string_index(np, "clock-output-names", 1, &init.name);
> +       if (ret) {
> +               dev_err(qmp->dev, "%pOFn: No clock-output-names index 1\n", np);
> +               return ret;
> +       }
> +
> +       init.ops = &clk_fixed_rate_ops;
> +
> +       fixed->fixed_rate = qmp->cfg->aux_clock_rate;
> +       fixed->hw.init = &init;
> +
> +       return devm_clk_hw_register(qmp->dev, &fixed->hw);
> +}
> +
> +static struct clk_hw *qmp_pcie_clk_hw_get(struct of_phandle_args *clkspec, void *data)
> +{
> +       struct qmp_pcie *qmp = data;
> +
> +       /* Support legacy bindings */
> +       if (!clkspec->args_count)
> +               return &qmp->pipe_clk_fixed.hw;
> +
> +       switch (clkspec->args[0]) {
> +       case QMP_PCIE_PIPE_CLK:
> +               return &qmp->pipe_clk_fixed.hw;
> +       case QMP_PCIE_PHY_AUX_CLK:
> +               return &qmp->aux_clk_fixed.hw;

Does the absence of the default case trigger a warning if compiled with W=1?

> +       }
> +
> +       return ERR_PTR(-EINVAL);
> +}
> +
>  static int qmp_pcie_register_clocks(struct qmp_pcie *qmp, struct device_node *np)
>  {
>         int ret;
> @@ -3694,9 +3756,19 @@ static int qmp_pcie_register_clocks(struct qmp_pcie *qmp, struct device_node *np
>         if (ret)
>                 return ret;
>
> -       ret = of_clk_add_hw_provider(np, of_clk_hw_simple_get, &qmp->pipe_clk_fixed.hw);
> -       if (ret)
> -               return ret;
> +       if (qmp->cfg->aux_clock_rate) {
> +               ret = phy_aux_clk_register(qmp, np);
> +               if (ret)
> +                       return ret;
> +
> +               ret = of_clk_add_hw_provider(np, qmp_pcie_clk_hw_get, qmp);
> +               if (ret)
> +                       return ret;
> +       } else {
> +               ret = of_clk_add_hw_provider(np, of_clk_hw_simple_get, &qmp->pipe_clk_fixed.hw);
> +               if (ret)
> +                       return ret;
> +       }
>
>         /*
>          * Roll a devm action because the clock provider is the child node, but
>
> --
> 2.34.1
>
>


-- 
With best wishes
Dmitry