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Date: Tue, 19 Mar 2024 15:35:25 +0100
From: Neil Armstrong <neil.armstrong@...aro.org>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: Bjorn Andersson <andersson@...nel.org>,
Konrad Dybcio <konrad.dybcio@...aro.org>, Vinod Koul <vkoul@...nel.org>,
Kishon Vijay Abraham I <kishon@...nel.org>, Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>, linux-arm-msm@...r.kernel.org,
linux-phy@...ts.infradead.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/7] phy: qcom: qmp-pcie: register second optional PHY AUX
clock
On 19/03/2024 11:59, Neil Armstrong wrote:
> On 19/03/2024 11:55, Dmitry Baryshkov wrote:
>> On Tue, 19 Mar 2024 at 12:45, Neil Armstrong <neil.armstrong@...aro.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.
>>>
>>> Signed-off-by: Neil Armstrong <neil.armstrong@...aro.org>
>>> ---
>>> drivers/phy/qualcomm/phy-qcom-qmp-pcie.c | 70 ++++++++++++++++++++++++++++++++
>>> 1 file changed, 70 insertions(+)
>>>
>>> diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
>>> index 079b3e306489..2d05226ae200 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)
>>> @@ -3681,6 +3687,62 @@ 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;
>>> + }
>>> +
>>> + return ERR_PTR(-EINVAL);
>>> +}
>>
>> Can we use of_clk_hw_onecell_get() instead? I think it even should be
>> possible to use onecell for both cases, it will look at the first arg,
>> which will be 0 in case of #clock-cells equal to 0.
>
> Let me investigate if it's possible
Ok, it would work but it would require building a clk_hw_onecell_data a runtime,
while we could simply provide this qmp_pcie_clk_hw_get() and avoid runtime 2 allocations.
I'm not sure it's worth it.
Neil
>
>>
>>> +
>>> static int qmp_pcie_register_clocks(struct qmp_pcie *qmp, struct device_node *np)
>>> {
>>> int ret;
>>> @@ -3689,6 +3751,14 @@ static int qmp_pcie_register_clocks(struct qmp_pcie *qmp, struct device_node *np
>>> if (ret)
>>> return ret;
>>>
>>> + if (qmp->cfg->aux_clock_rate) {
>>> + ret = phy_aux_clk_register(qmp, np);
>>> + if (ret)
>>> + return ret;
>>> +
>>> + return devm_of_clk_add_hw_provider(qmp->dev, qmp_pcie_clk_hw_get, qmp);
>>> + }
>>> +
>>> return devm_of_clk_add_hw_provider(qmp->dev, of_clk_hw_simple_get,
>>> &qmp->pipe_clk_fixed.hw);
>>> }
>>>
>>> --
>>> 2.34.1
>>>
>>>
>>
>>
>
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