Hello Mathieu,
On Fri, Feb 14, 2025 at 12:49:53PM +0100, mathieu.dubois-briand@xxxxxxxxxxx wrote:
> diff --git a/drivers/pwm/pwm-max7360.c b/drivers/pwm/pwm-max7360.c
> new file mode 100644
> index 000000000000..f1257c20add2
> --- /dev/null
> +++ b/drivers/pwm/pwm-max7360.c
> @@ -0,0 +1,213 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright 2024 Bootlin
> + *
> + * Author: Kamel BOUHARA <kamel.bouhara@xxxxxxxxxxx>
> + * Author: Mathieu Dubois-Briand <mathieu.dubois-briand@xxxxxxxxxxx>
> + *
> + * 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.
> + */
> +#include <linux/err.h>
> +#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 255
> +#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 *parent;
> + struct regmap *regmap;
> +};
> +
> +struct max7360_pwm_waveform {
> + u8 duty_steps;
> +};
> +
> +static inline struct max7360_pwm *max7360_pwm_from_chip(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 = max7360_pwm_from_chip(chip);
> + ret = max7360_port_pin_request(max7360_pwm->parent, pwm->hwpwm, true);
> + if (ret) {
> + dev_warn(&chip->dev, "failed to request pwm-%d\n", pwm->hwpwm);
Please drop this warning, just returning ret here is fine. (The rule of
thumb is: Emit runtime messages only in probe, not during usage.)
> + return ret;
> + }
> +
> + ret = regmap_write_bits(max7360_pwm->regmap,
> + MAX7360_REG_PWMCFG(pwm->hwpwm),
> + MAX7360_PWM_COMMON_PWN,
> + 0);
> + if (ret)
> + return ret;
> +
> + return regmap_write_bits(max7360_pwm->regmap, MAX7360_REG_PORTS,
> + MAX7360_PWM_PORT(pwm->hwpwm),
> + MAX7360_PWM_PORT(pwm->hwpwm));
> +}
> +
> +static void max7360_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> + struct max7360_pwm *max7360_pwm;
> +
> + max7360_pwm = max7360_pwm_from_chip(chip);
> + max7360_port_pin_request(max7360_pwm->parent, pwm->hwpwm, false);
Would be nice if pinmuxing would be abstracted as a pinctrl driver. Not
sure how much effort that is. Maybe Linus has an idea?
> +}
> +
> [...]
> +
> +static int max7360_pwm_write_waveform(struct pwm_chip *chip,
> + struct pwm_device *pwm,
> + const void *_wfhw)
> +{
> + const struct max7360_pwm_waveform *wfhw = _wfhw;
> + struct max7360_pwm *max7360_pwm;
> + unsigned int val;
> + int ret;
> +
> + max7360_pwm = max7360_pwm_from_chip(chip);
> +
> + val = (wfhw->duty_steps == 0) ? 0 : MAX7360_PWM_CTRL_ENABLE(pwm->hwpwm);
Does not setting MAX7360_PWM_CTRL_ENABLE result in the pin going to
Hi-Z? If yes: That's wrong. You're only supposed to do that if
period_length_ns = 0 was requested. If no: This needs a comment why
duty_steps = 0 is special here.
> + ret = regmap_write_bits(max7360_pwm->regmap, MAX7360_REG_GPIOCTRL,
> + MAX7360_PWM_CTRL_ENABLE(pwm->hwpwm), val);
> +
> + if (!ret && wfhw->duty_steps != 0) {
> + ret = regmap_write(max7360_pwm->regmap, MAX7360_REG_PWM(pwm->hwpwm),
> + wfhw->duty_steps);
> + }
> +
> + return ret;
> +}
> +
> +static int max7360_pwm_read_waveform(struct pwm_chip *chip,
> + struct pwm_device *pwm,
> + void *_wfhw)
> +{
> + struct max7360_pwm_waveform *wfhw = _wfhw;
> + struct max7360_pwm *max7360_pwm;
> + unsigned int val;
> + int ret;
> +
> + max7360_pwm = max7360_pwm_from_chip(chip);
> +
> + ret = regmap_read(max7360_pwm->regmap, MAX7360_REG_GPIOCTRL, &val);
> + if (ret)
> + return ret;
> +
> + if (val & MAX7360_PWM_CTRL_ENABLE(pwm->hwpwm)) {
> + ret = regmap_read(max7360_pwm->regmap, MAX7360_REG_PWM(pwm->hwpwm),
> + &val);
> + val = wfhw->duty_steps;
wfhw->duty_steps = val;
> + } else {
> + wfhw->duty_steps = 0;
> + }
> +
> + return ret;
> +}
Best regards
Uwe
Attachment:
signature.asc
Description: PGP signature
