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References: <20240322-topic-sm8x50-upstream-pcie-1-phy-aux-clk-v2-0-3ec0a966d52f@linaro.org>
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In-Reply-To: <1dc187c1-2005-486f-a9dd-6648cf52ab70@linaro.org>
From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Date: Fri, 22 Mar 2024 13:59:02 +0200
Message-ID: <CAA8EJprwAqCSpey0scgPHKEW7=DMKoh7EBmL2jtktKLwMM+rCQ@mail.gmail.com>
Subject: Re: [PATCH v2 3/7] phy: qcom: qmp-pcie: register second optional PHY
 AUX clock
To: neil.armstrong@linaro.org
Cc: Bjorn Andersson <andersson@kernel.org>, Konrad Dybcio <konrad.dybcio@linaro.org>, 
	Vinod Koul <vkoul@kernel.org>, Kishon Vijay Abraham I <kishon@kernel.org>, Rob Herring <robh@kernel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Conor Dooley <conor+dt@kernel.org>, 
	linux-arm-msm@vger.kernel.org, linux-phy@lists.infradead.org, 
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"

On Fri, 22 Mar 2024 at 12:45, Neil Armstrong <neil.armstrong@linaro.org> wrote:
>
> 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

Ok, great!

>
> 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
> >>
> >>
> >
> >
>


-- 
With best wishes
Dmitry