Re: [PATCH v14 04/10] pwm: max7360: Add MAX7360 PWM support

["Mathieu Dubois-Briand" <mathieu.dubois-briand@bootlin.com>]

On Sun Aug 24, 2025 at 1:57 PM CEST, Mathieu Dubois-Briand 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>
> Co-developed-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
> Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
>  drivers/pwm/Kconfig       |  10 +++
>  drivers/pwm/Makefile      |   1 +
>  drivers/pwm/pwm-max7360.c | 209 ++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 220 insertions(+)
>
> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> index f00ce973dddf..f2b1ce47de7f 100644
> --- a/drivers/pwm/Kconfig
> +++ b/drivers/pwm/Kconfig
> @@ -432,6 +432,16 @@ config PWM_LPSS_PLATFORM
>  	  To compile this driver as a module, choose M here: the module
>  	  will be called pwm-lpss-platform.
>  
> +config PWM_MAX7360
> +	tristate "MAX7360 PWMs"
> +	depends on MFD_MAX7360
> +	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.
> +
>  config PWM_MC33XS2410
>  	tristate "MC33XS2410 PWM support"
>  	depends on OF
> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> index ff4f47e5fb7a..dfa8b4966ee1 100644
> --- a/drivers/pwm/Makefile
> +++ b/drivers/pwm/Makefile
> @@ -38,6 +38,7 @@ 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_MC33XS2410)	+= pwm-mc33xs2410.o
>  obj-$(CONFIG_PWM_MEDIATEK)	+= pwm-mediatek.o
>  obj-$(CONFIG_PWM_MESON)		+= pwm-meson.o
> diff --git a/drivers/pwm/pwm-max7360.c b/drivers/pwm/pwm-max7360.c
> new file mode 100644
> index 000000000000..ebf93a7aee5b
> --- /dev/null
> +++ b/drivers/pwm/pwm-max7360.c
> @@ -0,0 +1,209 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright 2025 Bootlin
> + *
> + * Author: Kamel BOUHARA <kamel.bouhara@bootlin.com>
> + * Author: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
> + *
> + * PWM functionality of the MAX7360 multi-function device.
> + * https://www.analog.com/media/en/technical-documentation/data-sheets/MAX7360.pdf
> + *
> + * Limitations:
> + * - Only supports normal polarity.
> + * - The period is fixed to 2 ms.
> + * - Only the duty cycle can be changed, new values are applied at the beginning
> + *   of the next cycle.
> + * - When disabled, the output is put in Hi-Z immediately.
> + */
> +#include <linux/bits.h>
> +#include <linux/dev_printk.h>
> +#include <linux/err.h>
> +#include <linux/math64.h>
> +#include <linux/mfd/max7360.h>
> +#include <linux/minmax.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/pwm.h>
> +#include <linux/regmap.h>
> +#include <linux/time.h>
> +#include <linux/types.h>
> +
> +#define MAX7360_NUM_PWMS			8
> +#define MAX7360_PWM_MAX				255
> +#define MAX7360_PWM_STEPS			256
> +#define MAX7360_PWM_PERIOD_NS			(2 * NSEC_PER_MSEC)
> +
> +struct max7360_pwm_waveform {
> +	u8 duty_steps;
> +	bool enabled;
> +};
> +
> +static int max7360_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> +	struct regmap *regmap = pwmchip_get_drvdata(chip);
> +
> +	/*
> +	 * Make sure we use the individual PWM configuration register and not
> +	 * the global one.
> +	 * We never need to use the global one, so there is no need to revert
> +	 * that in the .free() callback.
> +	 */
> +	return regmap_write_bits(regmap, MAX7360_REG_PWMCFG(pwm->hwpwm),
> +				 MAX7360_PORT_CFG_COMMON_PWM, 0);
> +}
> +
> +static int max7360_pwm_round_waveform_tohw(struct pwm_chip *chip,
> +					   struct pwm_device *pwm,
> +					   const struct pwm_waveform *wf,
> +					   void *_wfhw)
> +{
> +	struct max7360_pwm_waveform *wfhw = _wfhw;
> +	u64 duty_steps;
> +
> +	/*
> +	 * Ignore user provided values for period_length_ns and duty_offset_ns:
> +	 * we only support fixed period of MAX7360_PWM_PERIOD_NS and offset of 0.
> +	 * Values from 0 to 254 as duty_steps will provide duty cycles of 0/256
> +	 * to 254/256, while value 255 will provide a duty cycle of 100%.
> +	 */
> +	if (wf->duty_length_ns >= MAX7360_PWM_PERIOD_NS) {
> +		duty_steps = MAX7360_PWM_MAX;
> +	} else {
> +		duty_steps = (u32)wf->duty_length_ns * MAX7360_PWM_STEPS / MAX7360_PWM_PERIOD_NS;
> +		if (duty_steps == MAX7360_PWM_MAX)
> +			duty_steps = MAX7360_PWM_MAX - 1;
> +	}
> +
> +	wfhw->duty_steps = min(MAX7360_PWM_MAX, duty_steps);
> +	wfhw->enabled = !!wf->period_length_ns;
> +
> +	if (wf->period_length_ns && wf->period_length_ns < MAX7360_PWM_PERIOD_NS)
> +		return 1;
> +	else
> +		return 0;
> +}
> +
> +static int max7360_pwm_round_waveform_fromhw(struct pwm_chip *chip, struct pwm_device *pwm,
> +					     const void *_wfhw, struct pwm_waveform *wf)
> +{
> +	const struct max7360_pwm_waveform *wfhw = _wfhw;
> +
> +	wf->period_length_ns = wfhw->enabled ? MAX7360_PWM_PERIOD_NS : 0;
> +	wf->duty_offset_ns = 0;
> +
> +	if (wfhw->enabled) {
> +		if (wfhw->duty_steps == MAX7360_PWM_MAX)
> +			wf->duty_length_ns = MAX7360_PWM_PERIOD_NS;
> +		else
> +			wf->duty_length_ns = DIV_ROUND_UP(wfhw->duty_steps * MAX7360_PWM_PERIOD_NS,
> +							  MAX7360_PWM_STEPS);
> +	} else {
> +		wf->duty_length_ns = 0;
> +	}
> +
> +	return 0;
> +}
> +
> +static int max7360_pwm_write_waveform(struct pwm_chip *chip,
> +				      struct pwm_device *pwm,
> +				      const void *_wfhw)
> +{
> +	struct regmap *regmap = pwmchip_get_drvdata(chip);
> +	const struct max7360_pwm_waveform *wfhw = _wfhw;
> +	unsigned int val;
> +	int ret;
> +
> +	if (wfhw->enabled) {
> +		ret = regmap_write(regmap, MAX7360_REG_PWM(pwm->hwpwm), wfhw->duty_steps);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	val = wfhw->enabled ? BIT(pwm->hwpwm) : 0;
> +	return regmap_write_bits(regmap, MAX7360_REG_GPIOCTRL, BIT(pwm->hwpwm), val);
> +}
> +
> +static int max7360_pwm_read_waveform(struct pwm_chip *chip,
> +				     struct pwm_device *pwm,
> +				     void *_wfhw)
> +{
> +	struct regmap *regmap = pwmchip_get_drvdata(chip);
> +	struct max7360_pwm_waveform *wfhw = _wfhw;
> +	unsigned int val;
> +	int ret;
> +
> +	ret = regmap_read(regmap, MAX7360_REG_GPIOCTRL, &val);
> +	if (ret)
> +		return ret;
> +
> +	if (val & BIT(pwm->hwpwm)) {
> +		wfhw->enabled = true;
> +		ret = regmap_read(regmap, MAX7360_REG_PWM(pwm->hwpwm), &val);
> +		if (ret)
> +			return ret;
> +
> +		wfhw->duty_steps = val;
> +	} else {
> +		wfhw->enabled = false;
> +		wfhw->duty_steps = 0;
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct pwm_ops max7360_pwm_ops = {
> +	.request = max7360_pwm_request,
> +	.round_waveform_tohw = max7360_pwm_round_waveform_tohw,
> +	.round_waveform_fromhw = max7360_pwm_round_waveform_fromhw,
> +	.read_waveform = max7360_pwm_read_waveform,
> +	.write_waveform = max7360_pwm_write_waveform,
> +};
> +
> +static int max7360_pwm_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct pwm_chip *chip;
> +	struct regmap *regmap;
> +	int ret;
> +
> +	regmap = dev_get_regmap(dev->parent, NULL);
> +	if (!regmap)
> +		return dev_err_probe(dev, -ENODEV, "Could not get parent regmap\n");
> +
> +	/*
> +	 * This MFD sub-device does not have any associated device tree node:
> +	 * properties are stored in the device node of the parent (MFD) device
> +	 * and this same node is used in phandles of client devices.
> +	 * Reuse this device tree node here, as otherwise the PWM subsystem
> +	 * would be confused by this topology.
> +	 */
> +	device_set_of_node_from_dev(dev, dev->parent);
> +
> +	chip = devm_pwmchip_alloc(dev, MAX7360_NUM_PWMS, 0);
> +	if (IS_ERR(chip))
> +		return PTR_ERR(chip);
> +	chip->ops = &max7360_pwm_ops;
> +
> +	pwmchip_set_drvdata(chip, regmap);
> +
> +	ret = devm_pwmchip_add(dev, chip);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "Failed to add PWM chip\n");
> +
> +	return 0;
> +}
> +
> +static struct platform_driver max7360_pwm_driver = {
> +	.driver = {
> +		.name = "max7360-pwm",
> +		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
> +	},
> +	.probe = max7360_pwm_probe,
> +};
> +module_platform_driver(max7360_pwm_driver);
> +
> +MODULE_DESCRIPTION("MAX7360 PWM driver");
> +MODULE_AUTHOR("Kamel BOUHARA <kamel.bouhara@bootlin.com>");
> +MODULE_AUTHOR("Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>");
> +MODULE_LICENSE("GPL");


Hi Uwe,

Any thought about this new version? I believe I fixed all the points we
have been discussing previously.

Thanks,
Mathieu

-- 
Mathieu Dubois-Briand, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com