// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2025 Marek Vasut
 *
 * Limitations:
 * - no support for offset/polarity
 * - fixed 30 kHz period
 *
 * Argon Fan HAT https://argon40.com/products/argon-fan-hat
 */

#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/pwm.h>

#define ARGON40_FAN_HAT_PERIOD_NS       33333   /* ~30 kHz */

#define ARGON40_FAN_HAT_REG_DUTY_CYCLE  0x80

static int argon_fan_hat_round_waveform_tohw(struct pwm_chip *chip,
                                             struct pwm_device *pwm,
                                             const struct pwm_waveform *wf,
                                             void *_wfhw)
{
        u8 *wfhw = _wfhw;

        if (wf->duty_length_ns > ARGON40_FAN_HAT_PERIOD_NS)
                *wfhw = 100;
        else
                *wfhw = mul_u64_u64_div_u64(wf->duty_length_ns, 100, ARGON40_FAN_HAT_PERIOD_NS);

        return 0;
}

static int argon_fan_hat_round_waveform_fromhw(struct pwm_chip *chip,
                                               struct pwm_device *pwm,
                                               const void *_wfhw,
                                               struct pwm_waveform *wf)
{
        const u8 *wfhw = _wfhw;

        wf->period_length_ns = ARGON40_FAN_HAT_PERIOD_NS;
        wf->duty_length_ns = DIV64_U64_ROUND_UP(wf->period_length_ns * *wfhw, 100);
        wf->duty_offset_ns = 0;

        return 0;
}

static int argon_fan_hat_write_waveform(struct pwm_chip *chip,
                                        struct pwm_device *pwm,
                                        const void *_wfhw)
{
        struct i2c_client *i2c = pwmchip_get_drvdata(chip);
        const u8 *wfhw = _wfhw;

        return i2c_smbus_write_byte_data(i2c, ARGON40_FAN_HAT_REG_DUTY_CYCLE, *wfhw);
}

static const struct pwm_ops argon_fan_hat_pwm_ops = {
        .sizeof_wfhw = sizeof(u8),
        .round_waveform_fromhw = argon_fan_hat_round_waveform_fromhw,
        .round_waveform_tohw = argon_fan_hat_round_waveform_tohw,
        .write_waveform = argon_fan_hat_write_waveform,
        /*
         * The controller does not provide any way to read info back,
         * reading from the controller stops the fan, therefore there
         * is no .read_waveform here.
         */
};

static int argon_fan_hat_i2c_probe(struct i2c_client *i2c)
{
        struct pwm_chip *chip = devm_pwmchip_alloc(&i2c->dev, 1, 0);
        int ret;

        if (IS_ERR(chip))
                return PTR_ERR(chip);

        chip->ops = &argon_fan_hat_pwm_ops;
        pwmchip_set_drvdata(chip, i2c);

        ret = devm_pwmchip_add(&i2c->dev, chip);
        if (ret)
                return dev_err_probe(&i2c->dev, ret, "Could not add PWM chip\n");

        return 0;
}

static const struct of_device_id argon_fan_hat_dt_ids[] = {
        { .compatible = "argon40,fan-hat" },
        { },
};
MODULE_DEVICE_TABLE(of, argon_fan_hat_dt_ids);

static struct i2c_driver argon_fan_hat_driver = {
        .driver = {
                .name = "argon-fan-hat",
                .probe_type = PROBE_PREFER_ASYNCHRONOUS,
                .of_match_table = argon_fan_hat_dt_ids,
        },
        .probe = argon_fan_hat_i2c_probe,
};

module_i2c_driver(argon_fan_hat_driver);

MODULE_AUTHOR("Marek Vasut <marek.vasut+renesas@mailbox.org>");
MODULE_DESCRIPTION("Argon40 Fan HAT");
MODULE_LICENSE("GPL");