linux-kernel - Re: [PATCH v14] pwm: opencores: Add PWM driver support

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Message-ID: <8ea19aa8-1c01-45ce-81e1-5b34f6738ac3@wanadoo.fr>
Date: Fri, 9 Aug 2024 14:27:39 +0200
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: William Qiu <william.qiu@...rfivetech.com>, linux-kernel@...r.kernel.org,
 linux-pwm@...r.kernel.org
Cc: Uwe Kleine-König <ukleinek@...nel.org>,
 Hal Feng <hal.feng@...rfivetech.com>, Philipp Zabel <p.zabel@...gutronix.de>
Subject: Re: [PATCH v14] pwm: opencores: Add PWM driver support

Le 09/08/2024 à 12:38, William Qiu a écrit :
> Add driver for OpenCores PWM Controller. And add compatibility code
> which based on StarFive SoC.
> 
> Co-developed-by: Hal Feng <hal.feng@...rfivetech.com>
> Signed-off-by: Hal Feng <hal.feng@...rfivetech.com>
> Signed-off-by: William Qiu <william.qiu@...rfivetech.com>
> ---

Hi,

...

> +static int ocores_pwm_apply(struct pwm_chip *chip,
> +			    struct pwm_device *pwm,
> +			    const struct pwm_state *state)
> +{
> +	struct ocores_pwm_device *ddata = chip_to_ocores(chip);
> +	u32 ctrl_data = 0;
> +	u64 period_data, duty_data;
> +
> +	if (state->polarity != PWM_POLARITY_INVERSED)
> +		return -EINVAL;
> +
> +	period_data = mul_u64_u32_div(state->period, ddata->clk_rate, NSEC_PER_SEC);
> +	if (!period_data)
> +		return -EINVAL;
> +
> +	if (period_data > U32_MAX)
> +		period_data = U32_MAX;
> +
> +	ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_LRC, (u32)period_data);
> +
> +	duty_data = mul_u64_u32_div(state->duty_cycle, ddata->clk_rate, NSEC_PER_SEC);
> +	if (duty_data <= U32_MAX)
> +		ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_HRC, (u32)duty_data);
> +	else if (duty_data > U32_MAX)
> +		duty_data = U32_MAX;
> +		ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_HRC, (u32)duty_data);

I guess that some {} are missing.
BTW, does it even compile without it???

> +	else
> +		return -EINVAL;

What is the use of this else?
duty_data is either <= U32_MAX or > U32_MAX.
Or I missed something?

Maybe just simplify things and write something as done with period_data 
just a few lines above?

> +
> +	ctrl_data = ocores_pwm_readl(ddata, pwm->hwpwm, REG_OCPWM_CTRL);
> +	if (state->enabled)
> +		ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_CTRL,
> +				  ctrl_data | REG_OCPWM_CNTR_EN | REG_OCPWM_CNTR_OE);
> +	else
> +		ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_CTRL,
> +				  ctrl_data & ~(REG_OCPWM_CNTR_EN | REG_OCPWM_CNTR_OE));
> +
> +	return 0;
> +}

...

> +static int ocores_pwm_probe(struct platform_device *pdev)
> +{
> +	const struct of_device_id *id;
> +	struct device *dev = &pdev->dev;
> +	struct ocores_pwm_device *ddata;
> +	struct pwm_chip *chip;
> +	struct clk *clk;
> +	struct reset_control *rst;
> +	int ret;
> +
> +	id = of_match_device(ocores_pwm_of_match, dev);
> +	if (!id)
> +		return -EINVAL;
> +
> +	chip = devm_pwmchip_alloc(&pdev->dev, 8, sizeof(*ddata));
> +	if (IS_ERR(chip))
> +		return -ENOMEM;
> +
> +	ddata = chip_to_ocores(chip);
> +	ddata->data = id->data;
> +	chip->ops = &ocores_pwm_ops;
> +
> +	ddata->regs = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(ddata->regs))
> +		return dev_err_probe(dev, PTR_ERR(ddata->regs),
> +				     "Unable to map IO resources\n");
> +
> +	clk = devm_clk_get_enabled(dev, NULL);
> +	if (IS_ERR(clk))
> +		return dev_err_probe(dev, PTR_ERR(clk),
> +				     "Unable to get pwm's clock\n");
> +
> +	ret = devm_clk_rate_exclusive_get(dev, clk);
> +	if (ret)
> +		return ret;
> +
> +	rst = devm_reset_control_get_optional_exclusive(dev, NULL);
> +	if (IS_ERR(rst))
> +		return dev_err_probe(dev, PTR_ERR(rst),
> +				     "Unable to get pwm's reset\n");
> +
> +	ret = reset_control_deassert(rst);
> +	if (ret)
> +		return ret;
> +
> +	ret = devm_add_action_or_reset(dev, ocores_pwm_reset_control_assert, rst);
> +	if (ret)
> +		return ret;
> +
> +	ddata->clk_rate = clk_get_rate(clk);
> +	if (ddata->clk_rate > NSEC_PER_SEC)
> +		return dev_err_probe(dev, ddata->clk_rate,

Does it work?
I would expect -EINVAL.

> +				     "Unable to get clock's rate\n");
> +
> +	ret = devm_pwmchip_add(dev, chip);
> +	if (ret < 0)
> +		return dev_err_probe(dev, ret, "Could not register PWM chip\n");
> +
> +	return 0;
> +}

...

CJ