1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2025 Marek Vasut
4 *
5 * Limitations:
6 * - no support for offset/polarity
7 * - fixed 30 kHz period
8 *
9 * Argon Fan HAT https://argon40.com/products/argon-fan-hat
10 */
11
12#include <linux/err.h>
13#include <linux/i2c.h>
14#include <linux/module.h>
15#include <linux/pwm.h>
16
17#define ARGON40_FAN_HAT_PERIOD_NS 33333 /* ~30 kHz */
18
19#define ARGON40_FAN_HAT_REG_DUTY_CYCLE 0x80
20
21static int argon_fan_hat_round_waveform_tohw(struct pwm_chip *chip,
22 struct pwm_device *pwm,
23 const struct pwm_waveform *wf,
24 void *_wfhw)
25{
26 u8 *wfhw = _wfhw;
27
28 if (wf->duty_length_ns > ARGON40_FAN_HAT_PERIOD_NS)
29 *wfhw = 100;
30 else
31 *wfhw = mul_u64_u64_div_u64(wf->duty_length_ns, 100, ARGON40_FAN_HAT_PERIOD_NS);
32
33 return 0;
34}
35
36static int argon_fan_hat_round_waveform_fromhw(struct pwm_chip *chip,
37 struct pwm_device *pwm,
38 const void *_wfhw,
39 struct pwm_waveform *wf)
40{
41 const u8 *wfhw = _wfhw;
42
43 wf->period_length_ns = ARGON40_FAN_HAT_PERIOD_NS;
44 wf->duty_length_ns = DIV64_U64_ROUND_UP(wf->period_length_ns * *wfhw, 100);
45 wf->duty_offset_ns = 0;
46
47 return 0;
48}
49
50static int argon_fan_hat_write_waveform(struct pwm_chip *chip,
51 struct pwm_device *pwm,
52 const void *_wfhw)
53{
54 struct i2c_client *i2c = pwmchip_get_drvdata(chip);
55 const u8 *wfhw = _wfhw;
56
57 return i2c_smbus_write_byte_data(client: i2c, ARGON40_FAN_HAT_REG_DUTY_CYCLE, value: *wfhw);
58}
59
60static const struct pwm_ops argon_fan_hat_pwm_ops = {
61 .sizeof_wfhw = sizeof(u8),
62 .round_waveform_fromhw = argon_fan_hat_round_waveform_fromhw,
63 .round_waveform_tohw = argon_fan_hat_round_waveform_tohw,
64 .write_waveform = argon_fan_hat_write_waveform,
65 /*
66 * The controller does not provide any way to read info back,
67 * reading from the controller stops the fan, therefore there
68 * is no .read_waveform here.
69 */
70};
71
72static int argon_fan_hat_i2c_probe(struct i2c_client *i2c)
73{
74 struct pwm_chip *chip = devm_pwmchip_alloc(parent: &i2c->dev, npwm: 1, sizeof_priv: 0);
75 int ret;
76
77 if (IS_ERR(ptr: chip))
78 return PTR_ERR(ptr: chip);
79
80 chip->ops = &argon_fan_hat_pwm_ops;
81 pwmchip_set_drvdata(chip, data: i2c);
82
83 ret = devm_pwmchip_add(&i2c->dev, chip);
84 if (ret)
85 return dev_err_probe(dev: &i2c->dev, err: ret, fmt: "Could not add PWM chip\n");
86
87 return 0;
88}
89
90static const struct of_device_id argon_fan_hat_dt_ids[] = {
91 { .compatible = "argon40,fan-hat" },
92 { },
93};
94MODULE_DEVICE_TABLE(of, argon_fan_hat_dt_ids);
95
96static struct i2c_driver argon_fan_hat_driver = {
97 .driver = {
98 .name = "argon-fan-hat",
99 .probe_type = PROBE_PREFER_ASYNCHRONOUS,
100 .of_match_table = argon_fan_hat_dt_ids,
101 },
102 .probe = argon_fan_hat_i2c_probe,
103};
104
105module_i2c_driver(argon_fan_hat_driver);
106
107MODULE_AUTHOR("Marek Vasut <marek.vasut+renesas@mailbox.org>");
108MODULE_DESCRIPTION("Argon40 Fan HAT");
109MODULE_LICENSE("GPL");
110

source code of linux/drivers/pwm/pwm-argon-fan-hat.c