Re: [PATCH v4 4/6] pwm: meson: use device data to carry information around

[Uwe Kleine-König]

On Fri, Dec 22, 2023 at 12:16:52PM +0100, Jerome Brunet wrote:
> Use struct device data to carry the information data around, instead
> of embedded the pwm structure in it and using container_of()
> 
> Doing so works just as well and makes it a little easier to add setup
> callback depending on the DT compatible.
> 
> Signed-off-by: Jerome Brunet <jbrunet@xxxxxxxxxxxx>
> ---
>  drivers/pwm/pwm-meson.c | 39 +++++++++++++++++++++++----------------
>  1 file changed, 23 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c
> index ef50c337f444..15c44185d784 100644
> --- a/drivers/pwm/pwm-meson.c
> +++ b/drivers/pwm/pwm-meson.c
> @@ -101,7 +101,6 @@ struct meson_pwm_data {
>  };
>  
>  struct meson_pwm {
> -	struct pwm_chip chip;
>  	const struct meson_pwm_data *data;
>  	struct meson_pwm_channel channels[MESON_NUM_PWMS];
>  	void __iomem *base;
> @@ -114,7 +113,7 @@ struct meson_pwm {
>  
>  static inline struct meson_pwm *to_meson_pwm(struct pwm_chip *chip)
>  {
> -	return container_of(chip, struct meson_pwm, chip);
> +	return dev_get_drvdata(chip->dev);
>  }
>  
>  static int meson_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
> @@ -146,6 +145,7 @@ static int meson_pwm_calc(struct meson_pwm *meson, struct pwm_device *pwm,
>  			  const struct pwm_state *state)
>  {
>  	struct meson_pwm_channel *channel = &meson->channels[pwm->hwpwm];
> +	struct device *dev = pwm->chip->dev;
>  	unsigned int cnt, duty_cnt;
>  	unsigned long fin_freq;
>  	u64 duty, period, freq;
> @@ -168,19 +168,19 @@ static int meson_pwm_calc(struct meson_pwm *meson, struct pwm_device *pwm,
>  
>  	fin_freq = clk_round_rate(channel->clk, freq);
>  	if (fin_freq == 0) {
> -		dev_err(meson->chip.dev, "invalid source clock frequency\n");
> +		dev_err(dev, "invalid source clock frequency\n");
>  		return -EINVAL;
>  	}
>  
> -	dev_dbg(meson->chip.dev, "fin_freq: %lu Hz\n", fin_freq);
> +	dev_dbg(dev, "fin_freq: %lu Hz\n", fin_freq);
>  
>  	cnt = div_u64(fin_freq * period, NSEC_PER_SEC);
>  	if (cnt > 0xffff) {
> -		dev_err(meson->chip.dev, "unable to get period cnt\n");
> +		dev_err(dev, "unable to get period cnt\n");
>  		return -EINVAL;
>  	}
>  
> -	dev_dbg(meson->chip.dev, "period=%llu cnt=%u\n", period, cnt);
> +	dev_dbg(dev, "period=%llu cnt=%u\n", period, cnt);
>  
>  	if (duty == period) {
>  		channel->hi = cnt;
> @@ -191,7 +191,7 @@ static int meson_pwm_calc(struct meson_pwm *meson, struct pwm_device *pwm,
>  	} else {
>  		duty_cnt = div_u64(fin_freq * duty, NSEC_PER_SEC);
>  
> -		dev_dbg(meson->chip.dev, "duty=%llu duty_cnt=%u\n", duty, duty_cnt);
> +		dev_dbg(dev, "duty=%llu duty_cnt=%u\n", duty, duty_cnt);
>  
>  		channel->hi = duty_cnt;
>  		channel->lo = cnt - duty_cnt;
> @@ -214,7 +214,7 @@ static void meson_pwm_enable(struct meson_pwm *meson, struct pwm_device *pwm)
>  
>  	err = clk_set_rate(channel->clk, channel->rate);
>  	if (err)
> -		dev_err(meson->chip.dev, "setting clock rate failed\n");
> +		dev_err(pwm->chip->dev, "setting clock rate failed\n");
>  
>  	spin_lock_irqsave(&meson->lock, flags);
>  
> @@ -425,10 +425,10 @@ static const struct of_device_id meson_pwm_matches[] = {
>  };
>  MODULE_DEVICE_TABLE(of, meson_pwm_matches);
>  
> -static int meson_pwm_init_channels(struct meson_pwm *meson)
> +static int meson_pwm_init_channels(struct device *dev)
>  {
>  	struct clk_parent_data mux_parent_data[MESON_NUM_MUX_PARENTS] = {};
> -	struct device *dev = meson->chip.dev;
> +	struct meson_pwm *meson = dev_get_drvdata(dev);
>  	unsigned int i;
>  	char name[255];
>  	int err;
> @@ -438,7 +438,7 @@ static int meson_pwm_init_channels(struct meson_pwm *meson)
>  		mux_parent_data[i].name = meson->data->parent_names[i];
>  	}
>  
> -	for (i = 0; i < meson->chip.npwm; i++) {
> +	for (i = 0; i < MESON_NUM_PWMS; i++) {
>  		struct meson_pwm_channel *channel = &meson->channels[i];
>  		struct clk_parent_data div_parent = {}, gate_parent = {};
>  		struct clk_init_data init = {};
> @@ -519,28 +519,35 @@ static int meson_pwm_init_channels(struct meson_pwm *meson)
>  static int meson_pwm_probe(struct platform_device *pdev)
>  {
>  	struct meson_pwm *meson;
> +	struct pwm_chip *chip;
>  	int err;
>  
> +	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
> +	if (!chip)
> +		return -ENOMEM;
> +
>  	meson = devm_kzalloc(&pdev->dev, sizeof(*meson), GFP_KERNEL);
>  	if (!meson)
>  		return -ENOMEM;
>  
> +	platform_set_drvdata(pdev, meson);
> +
>  	meson->base = devm_platform_ioremap_resource(pdev, 0);
>  	if (IS_ERR(meson->base))
>  		return PTR_ERR(meson->base);
>  
>  	spin_lock_init(&meson->lock);
> -	meson->chip.dev = &pdev->dev;
> -	meson->chip.ops = &meson_pwm_ops;
> -	meson->chip.npwm = MESON_NUM_PWMS;
> +	chip->dev = &pdev->dev;
> +	chip->ops = &meson_pwm_ops;
> +	chip->npwm = MESON_NUM_PWMS;
>  
>  	meson->data = of_device_get_match_data(&pdev->dev);
>  
> -	err = meson_pwm_init_channels(meson);
> +	err = meson_pwm_init_channels(&pdev->dev);
>  	if (err < 0)
>  		return err;
>  
> -	err = devm_pwmchip_add(&pdev->dev, &meson->chip);
> +	err = devm_pwmchip_add(&pdev->dev, chip);
>  	if (err < 0)
>  		return dev_err_probe(&pdev->dev, err,
>  				     "failed to register PWM chip\n");

Parts of this change overlap with plans I have for this driver. I
reworked the series a bit now, also affecting the meson driver, the
previous submission is available at https://lore.kernel.org/linux-pwm/bf6f7c6253041f60ee8f35b5c9c9e8d595332fb0.1706182805.git.u.kleine-koenig@xxxxxxxxxxxxxx

I don't see the nice benefit of this patch yet, but I assume this will
become clearer when I check the next patch.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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