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// 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");
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