linux-kernel - Re: [PATCH V3 RESEND] pwm: meson: add pwm support for S4

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Message-ID: <62ab75f8-0e15-441a-b6b3-0b8cc138419b@amlogic.com>
Date:   Fri, 27 Oct 2023 17:22:21 +0800
From:   Junyi Zhao <junyi.zhao@...ogic.com>
To:     George Stark <gnstark@...utedevices.com>,
        Yixun Lan <dlan@...too.org>
Cc:     thierry.reding@...il.com, u.kleine-koenig@...gutronix.de,
        neil.armstrong@...aro.org, khilman@...libre.com,
        jbrunet@...libre.com, martin.blumenstingl@...glemail.com,
        linux-pwm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3 RESEND] pwm: meson: add pwm support for S4

Hello YiXun，
  CLK config has been separated on HW. No more in pwmchip.
And s4 datasheet about clk updated already.

On 2023/10/24 3:40, George Stark wrote:
> [你通常不会收到来自 gnstark@...utedevices.com 的电子邮件。请访问 
> https://aka.ms/LearnAboutSenderIdentification，以了解这一点为什么很重要]
> 
> [ EXTERNAL EMAIL ]
> 
> Hello Yixun Lan
> 
> On 10/17/23 01:37, Yixun Lan wrote:
>> Hi JunYi
>>
>> On 13:24 Mon 16 Oct     , JunYi Zhao wrote:
>>> From: "junyi.zhao" <junyi.zhao@...ogic.com>
>>>
>>> Support PWM for S4 soc.
>>> Now the PWM clock input is done in independent CLKCTRL registers.
>>> And no more in the PWM registers.
>>> PWM needs to obtain an external clock source.
>>>
>>> Signed-off-by: junyi.zhao <junyi.zhao@...ogic.com>
>>> ---
>>> V2 -> V3:
>>> Rebase and Review the latest upstream code again.
>>> After reconstruction, stick to the previous code as much as possible.
>>>   drivers/pwm/pwm-meson.c | 19 +++++++++++++++++++
>>>   1 file changed, 19 insertions(+)
>>>
>>> diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c
>>> index 25519cddc2a9..fe9fd75747c4 100644
>>> --- a/drivers/pwm/pwm-meson.c
>>> +++ b/drivers/pwm/pwm-meson.c
>>> @@ -99,6 +99,7 @@ struct meson_pwm_channel {
>>>   struct meson_pwm_data {
>>>      const char * const *parent_names;
>>>      unsigned int num_parents;
>>> +    unsigned int extern_clk;
>>>   };
>>>
>>>   struct meson_pwm {
>>> @@ -396,6 +397,10 @@ static const struct meson_pwm_data 
>>> pwm_g12a_ao_cd_data = {
>>>      .num_parents = ARRAY_SIZE(pwm_g12a_ao_cd_parent_names),
>>>   };
>>>
>>> +static const struct meson_pwm_data pwm_s4_data = {
>>> +    .extern_clk = true,
>>> +};
>>> +
>>>   static const struct of_device_id meson_pwm_matches[] = {
>>>      {
>>>              .compatible = "amlogic,meson8b-pwm",
>>> @@ -429,6 +434,10 @@ static const struct of_device_id 
>>> meson_pwm_matches[] = {
>>>              .compatible = "amlogic,meson-g12a-ao-pwm-cd",
>>>              .data = &pwm_g12a_ao_cd_data
>>>      },
>>> +    {
>>> +            .compatible = "amlogic,s4-pwm",
>>> +            .data = &pwm_s4_data,
>>> +    },
>>>      {},
>>>   };
>>>   MODULE_DEVICE_TABLE(of, meson_pwm_matches);
>>> @@ -451,6 +460,16 @@ static int meson_pwm_init_channels(struct 
>>> meson_pwm *meson)
>>>              struct clk_parent_data div_parent = {}, gate_parent = {};
>>>              struct clk_init_data init = {};
>>>
>>> +            if (meson->data->extern_clk) {
>>> +                    snprintf(name, sizeof(name), "clkin%u", i);
>>> +                    channel->clk = devm_clk_get(dev, name);
>> use devm_clk_get_optional() which would save you from introducing
>> the 'extern_clk' variable
> 
> On S4 and other recent chips PWM clock resides in separate IP and it
> must be provided to driver in order to control PWM frequency. So this
> clock is not optional.
> 
>>
>>> +                    if (IS_ERR(channel->clk)) {
>>> +                            dev_err(meson->chip.dev, "can't get 
>>> device clock\n");
>>> +                            return PTR_ERR(channel->clk);
>>> +                    }
>>> +                    continue;
>>> +            }
>>> +
>>>              snprintf(name, sizeof(name), "%s#mux%u", dev_name(dev), i);
>>>
>>>              init.name = name;
>>>
>>> base-commit: 4d2c646ac07cf4a35ef1c4a935a1a4fd6c6b1a36
>>> -- 
>>> 2.41.0
>>>
>>>
>>> _______________________________________________
>>> linux-amlogic mailing list
>>> linux-amlogic@...ts.infradead.org
>>> http://lists.infradead.org/mailman/listinfo/linux-amlogic
>>
> 
> -- 
> Best regards
> George

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