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Message-ID: <l5crrk3ugpo2ggjtykcy5eretclgntebyq52xuouekoimbrsvh@u4koyu5z2wwi>
Date: Mon, 18 Aug 2025 11:05:32 +0200
From: Uwe Kleine-König <ukleinek@...nel.org>
To: Mathieu Dubois-Briand <mathieu.dubois-briand@...tlin.com>
Cc: Lee Jones <lee@...nel.org>, Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>,
Kamel Bouhara <kamel.bouhara@...tlin.com>, Linus Walleij <linus.walleij@...aro.org>,
Bartosz Golaszewski <brgl@...ev.pl>, Dmitry Torokhov <dmitry.torokhov@...il.com>,
Michael Walle <mwalle@...nel.org>, Mark Brown <broonie@...nel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>, "Rafael J. Wysocki" <rafael@...nel.org>,
Danilo Krummrich <dakr@...nel.org>, devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-gpio@...r.kernel.org, linux-input@...r.kernel.org, linux-pwm@...r.kernel.org,
andriy.shevchenko@...el.com, Grégory Clement <gregory.clement@...tlin.com>,
Thomas Petazzoni <thomas.petazzoni@...tlin.com>, Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: Re: [PATCH v13 04/10] pwm: max7360: Add MAX7360 PWM support
Hello,
On Mon, Aug 11, 2025 at 12:46:22PM +0200, Mathieu Dubois-Briand wrote:
> From: Kamel Bouhara <kamel.bouhara@...tlin.com>
>
> Add driver for Maxim Integrated MAX7360 PWM controller, supporting up to
> 8 independent PWM outputs.
>
> Signed-off-by: Kamel Bouhara <kamel.bouhara@...tlin.com>
> Co-developed-by: Mathieu Dubois-Briand <mathieu.dubois-briand@...tlin.com>
> Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@...tlin.com>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.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..5a0c10d2320e
> --- /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@...tlin.com>
> + * Author: Mathieu Dubois-Briand <mathieu.dubois-briand@...tlin.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 < MAX7360_PWM_PERIOD_NS)
I know this code was suggested as is by me, but I think we need:
if (wf->period_length_ns && wf->period_length_ns < MAX7360_PWM_PERIOD_NS)
here to prevent to trigger a PWM_DEBUG warning. Sorry to spot this only
now.
> + return 1;
> + else
> + return 0;
> +}
Best regards
Uwe
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