[4/8] pwm: max7360: Add MAX7360 PWM support

From: Kamel Bouhara <kamel.bouhara@bootlin.com>

Add driver for Maxim Integrated MAX7360 PWM controller, supporting up to
8 independent PWM outputs.

Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
---
 drivers/pwm/Kconfig       |  11 +++
 drivers/pwm/Makefile      |   1 +
 drivers/pwm/pwm-max7360.c | 173 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 185 insertions(+)

Hello,

On Thu, Dec 19, 2024 at 05:21:21PM +0100, mathieu.dubois-briand@bootlin.com wrote:
> From: Kamel Bouhara <kamel.bouhara@bootlin.com>
> 
> Add driver for Maxim Integrated MAX7360 PWM controller, supporting up to
> 8 independent PWM outputs.
> 
> Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
> Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
> ---
>  drivers/pwm/Kconfig       |  11 +++
>  drivers/pwm/Makefile      |   1 +
>  drivers/pwm/pwm-max7360.c | 173 ++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 185 insertions(+)
> 
> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> index 0915c1e7df16..399dc3f76e92 100644
> --- a/drivers/pwm/Kconfig
> +++ b/drivers/pwm/Kconfig
> @@ -745,4 +745,15 @@ config PWM_XILINX
>  	  To compile this driver as a module, choose M here: the module
>  	  will be called pwm-xilinx.
>  
> +config PWM_MAX7360
> +	tristate "MAX7360 PWMs"
> +	depends on MFD_MAX7360
> +	depends on OF_GPIO
> +	help
> +	  PWM driver for Maxim Integrated MAX7360 multifunction device, with
> +	  support for up to 8 PWM outputs.
> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called pwm-max7360.
> +
>  endif
> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> index 9081e0c0e9e0..ae8908ffc892 100644
> --- a/drivers/pwm/Makefile
> +++ b/drivers/pwm/Makefile
> @@ -36,6 +36,7 @@ obj-$(CONFIG_PWM_LPC32XX)	+= pwm-lpc32xx.o
>  obj-$(CONFIG_PWM_LPSS)		+= pwm-lpss.o
>  obj-$(CONFIG_PWM_LPSS_PCI)	+= pwm-lpss-pci.o
>  obj-$(CONFIG_PWM_LPSS_PLATFORM)	+= pwm-lpss-platform.o
> +obj-$(CONFIG_PWM_MAX7360)	+= pwm-max7360.o
>  obj-$(CONFIG_PWM_MESON)		+= pwm-meson.o
>  obj-$(CONFIG_PWM_MEDIATEK)	+= pwm-mediatek.o
>  obj-$(CONFIG_PWM_MICROCHIP_CORE)	+= pwm-microchip-core.o
> diff --git a/drivers/pwm/pwm-max7360.c b/drivers/pwm/pwm-max7360.c
> new file mode 100644
> index 000000000000..b1cde3e86864
> --- /dev/null
> +++ b/drivers/pwm/pwm-max7360.c
> @@ -0,0 +1,173 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright 2024 Bootlin
> + *
> + * Author: Kamel BOUHARA <kamel.bouhara@bootlin.com>
> + */
> +#include <linux/math.h>
> +#include <linux/mfd/max7360.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/pwm.h>
> +#include <linux/regmap.h>
> +
> +#define MAX7360_NUM_PWMS			8
> +#define MAX7360_PWM_MAX_RES			256
> +#define MAX7360_PWM_PERIOD_NS			2000000 /* 500 Hz */
> +#define MAX7360_PWM_COMMON_PWN			BIT(5)
> +#define MAX7360_PWM_CTRL_ENABLE(n)		BIT(n)
> +#define MAX7360_PWM_PORT(n)			BIT(n)
> +
> +struct max7360_pwm {
> +	struct device *dev;
> +	struct regmap *regmap;
> +};
> +
> +static inline struct max7360_pwm *to_max7360_pwm(struct pwm_chip *chip)
> +{
> +	return pwmchip_get_drvdata(chip);
> +}
> +
> +static int max7360_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> +	struct max7360_pwm *max7360_pwm;
> +	int ret;
> +
> +	max7360_pwm = to_max7360_pwm(chip);
> +	ret = max7360_port_pin_request(max7360_pwm->dev->parent, pwm->hwpwm,
> +				       true);
> +	if (ret) {
> +		dev_err(&chip->dev, "failed to request pwm-%d\n", pwm->hwpwm);

Please no error messages after probe.

> +		return ret;
> +	}
> +
> +	ret = regmap_write_bits(max7360_pwm->regmap,
> +				MAX7360_REG_PWMCFG + pwm->hwpwm,
> +				MAX7360_PWM_COMMON_PWN,
> +				0);
> +	if (ret) {
> +		dev_err(&chip->dev, "failed to write pwm-%d cfg register, error %d\n",
> +			pwm->hwpwm, ret);
> +		return ret;
> +	}
> +
> +	ret = regmap_write_bits(max7360_pwm->regmap, MAX7360_REG_PORTS,
> +				MAX7360_PWM_PORT(pwm->hwpwm),
> +				MAX7360_PWM_PORT(pwm->hwpwm));
> +	if (ret) {
> +		dev_err(&chip->dev, "failed to write pwm-%d ports register, error %d\n",
> +			pwm->hwpwm, ret);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void max7360_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> +	struct max7360_pwm *max7360_pwm;
> +	int ret;
> +
> +	max7360_pwm = to_max7360_pwm(chip);
> +	ret = regmap_write_bits(max7360_pwm->regmap, MAX7360_REG_GPIOCTRL,
> +				MAX7360_PWM_CTRL_ENABLE(pwm->hwpwm),
> +				0);
> +	if (ret)
> +		dev_err(&chip->dev, "failed to enable pwm-%d , error %d\n",
> +			pwm->hwpwm, ret);
> +
> +	max7360_port_pin_request(max7360_pwm->dev->parent, pwm->hwpwm,
> +				 false);
> +}
> +
> +static int max7360_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> +			     const struct pwm_state *state)
> +{
> +	struct max7360_pwm *max7360_pwm;
> +	u64 duty_steps = state->duty_cycle * MAX7360_PWM_MAX_RES;

This might overflow.

> +	int ret;
> +
> +	if (state->polarity != PWM_POLARITY_NORMAL)
> +		return -EINVAL;
> +
> +	max7360_pwm = to_max7360_pwm(chip);
> +	ret = regmap_write_bits(max7360_pwm->regmap, MAX7360_REG_GPIOCTRL,
> +				MAX7360_PWM_CTRL_ENABLE(pwm->hwpwm),
> +				MAX7360_PWM_CTRL_ENABLE(pwm->hwpwm));
> +	if (ret) {
> +		dev_err(&chip->dev, "failed to enable pwm-%d , error %d\n",
> +			pwm->hwpwm, ret);
> +		return ret;
> +	}
> +
> +	do_div(duty_steps, MAX7360_PWM_PERIOD_NS);
> +
> +	ret = regmap_write(max7360_pwm->regmap, MAX7360_REG_PWMBASE + pwm->hwpwm,
> +			   duty_steps >= 255 ? 255 : duty_steps);
> +	if (ret) {
> +		dev_err(&chip->dev,
> +			"failed to apply pwm duty_cycle %llu on pwm-%d, error %d\n",
> +			duty_steps, pwm->hwpwm, ret);
> +		return ret;
> +	}

Huh, state->period isn't used at all. That is wrong for sure.

> +
> +	return 0;
> +}
> +
> +static const struct pwm_ops max7360_pwm_ops = {
> +	.request = max7360_pwm_request,
> +	.free = max7360_pwm_free,
> +	.apply = max7360_pwm_apply,

Please implement .get_state() (or the new waveform callbacks)

> +};
> +
> +static int max7360_pwm_probe(struct platform_device *pdev)
> +{
> +	struct max7360_pwm *max7360_pwm;
> +	struct pwm_chip *chip;
> +
> +	if (!pdev->dev.parent) {
> +		dev_err(&pdev->dev, "no parent device\n");
> +		return -ENODEV;

return dev_err_probe(...);

> +	}
> +
> +	chip = devm_pwmchip_alloc(&pdev->dev, MAX7360_NUM_PWMS,
> +				  sizeof(*max7360_pwm));
> +	if (IS_ERR(chip))
> +		return PTR_ERR(chip);
> +	chip->ops = &max7360_pwm_ops;
> +
> +	max7360_pwm = to_max7360_pwm(chip);
> +	max7360_pwm->dev = &pdev->dev;

This is only ever used to get max7360_pwm->dev->parent; so better store
the parent directly in max7360_pwm.

> +
> +	max7360_pwm->regmap = dev_get_regmap(pdev->dev.parent, NULL);
> +	if (!max7360_pwm->regmap) {
> +		dev_err(&pdev->dev, "could not get parent regmap\n");
> +		return -ENODEV;
> +	}
> +
> +	return devm_pwmchip_add(&pdev->dev, chip);

error message please

> +}
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id max7360_pwm_of_match[] = {
> +	{ .compatible = "maxim,max7360-pwm", },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, max7360_pwm_of_match);
> +#endif

Please drop the CONFIG_OF guard.

> +
> +static struct platform_driver max7360_pwm_driver = {
> +	.driver = {
> +		.name = "max7360-pwm",
> +		.of_match_table = of_match_ptr(max7360_pwm_of_match),
> +	},
> +	.probe = max7360_pwm_probe,
> +};
> +module_platform_driver(max7360_pwm_driver);
> +
> +MODULE_DESCRIPTION("MAX7360 PWM driver");
> +MODULE_AUTHOR("Kamel BOUHARA <kamel.bouhara@bootlin.com>");
> +MODULE_ALIAS("platform:max7360-pwm");
> +MODULE_LICENSE("GPL");

Hello again,

On Thu, Dec 19, 2024 at 05:21:21PM +0100, mathieu.dubois-briand@bootlin.com wrote:
> diff --git a/drivers/pwm/pwm-max7360.c b/drivers/pwm/pwm-max7360.c
> new file mode 100644
> index 000000000000..b1cde3e86864
> --- /dev/null
> +++ b/drivers/pwm/pwm-max7360.c
> @@ -0,0 +1,173 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright 2024 Bootlin
> + *

I forgot: Please also add a paragraph here describing the relevant
features here in the format that several other drivers use. Such that

	sed -rn '/Limitations:/,/\*\/?$/p' drivers/pwm/*.c

emits it. Relevant are at least:

 - Only supports normal polarity

 - How does it behave on disable? (Constant low? Freeze at the level
   where it just happens to be? High-Z?)

 - How does it behave on reconfiguration? (counter reset? Mixed output
   possible?

Best regards
Uwe

On 19/12/2024 17:21, mathieu.dubois-briand@bootlin.com wrote:
> From: Kamel Bouhara <kamel.bouhara@bootlin.com>
> 
> Add driver for Maxim Integrated MAX7360 PWM controller, supporting up to
> 8 independent PWM outputs.
> 


...

> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id max7360_pwm_of_match[] = {
> +	{ .compatible = "maxim,max7360-pwm", },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, max7360_pwm_of_match);
> +#endif
> +
> +static struct platform_driver max7360_pwm_driver = {
> +	.driver = {
> +		.name = "max7360-pwm",
> +		.of_match_table = of_match_ptr(max7360_pwm_of_match),

Better to drop of_match_ptr and #ifdef earlier, so ACPI could use it.

> +	},
> +	.probe = max7360_pwm_probe,
> +};
> +module_platform_driver(max7360_pwm_driver);
> +
> +MODULE_DESCRIPTION("MAX7360 PWM driver");
> +MODULE_AUTHOR("Kamel BOUHARA <kamel.bouhara@bootlin.com>");
> +MODULE_ALIAS("platform:max7360-pwm");


You should not need MODULE_ALIAS() in normal cases. If you need it,
usually it means your device ID table is wrong (e.g. misses either
entries or MODULE_DEVICE_TABLE()). MODULE_ALIAS() is not a substitute
for incomplete ID table.

Maybe you need it because OF table will get dropped, then it would be
fine. But in current code it's unnecessary and copy-pasta from other
drivers.


Best regards,
Krzysztof

On Thu Dec 19, 2024 at 10:53 PM CET, Uwe Kleine-König wrote:
> Hello,
>
> On Thu, Dec 19, 2024 at 05:21:21PM +0100, mathieu.dubois-briand@bootlin.com wrote:
> > From: Kamel Bouhara <kamel.bouhara@bootlin.com>
> > 
> > +	int ret;
> > +
> > +	if (state->polarity != PWM_POLARITY_NORMAL)
> > +		return -EINVAL;
> > +
> > +	max7360_pwm = to_max7360_pwm(chip);
> > +	ret = regmap_write_bits(max7360_pwm->regmap, MAX7360_REG_GPIOCTRL,
> > +				MAX7360_PWM_CTRL_ENABLE(pwm->hwpwm),
> > +				MAX7360_PWM_CTRL_ENABLE(pwm->hwpwm));
> > +	if (ret) {
> > +		dev_err(&chip->dev, "failed to enable pwm-%d , error %d\n",
> > +			pwm->hwpwm, ret);
> > +		return ret;
> > +	}
> > +
> > +	do_div(duty_steps, MAX7360_PWM_PERIOD_NS);
> > +
> > +	ret = regmap_write(max7360_pwm->regmap, MAX7360_REG_PWMBASE + pwm->hwpwm,
> > +			   duty_steps >= 255 ? 255 : duty_steps);
> > +	if (ret) {
> > +		dev_err(&chip->dev,
> > +			"failed to apply pwm duty_cycle %llu on pwm-%d, error %d\n",
> > +			duty_steps, pwm->hwpwm, ret);
> > +		return ret;
> > +	}
>
> Huh, state->period isn't used at all. That is wrong for sure.
>

Yes this was definitely missing. Period is fixed by the chip, so I will
make sure the requested one is valid or return -EINVAL.

Thanks a lot for your review, I am preparing a new version of this
series that should address all your comments.