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

[Neil Armstrong <neil.armstrong@linaro.org>]

On 22/03/2024 11:41, Dmitry Baryshkov wrote:
> On Fri, 22 Mar 2024 at 11:43, Neil Armstrong <neil.armstrong@linaro.org> 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@linaro.org>
> 
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> 
> 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?

Nop it doesn't with GCC arm-gnu-toolchain-13.2.Rel1-x86_64-aarch64-none-linux-gnu + W=1 and with smatch and C=1

Neil

> 
>> +       }
>> +
>> +       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
>>
>>
> 
>