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0191c80e8a
Add trivial PWM driver for Argon40 Fan HAT, which is a RaspberryPi blower fan hat which can be controlled over I2C. Model this device as a PWM, so the pwm-fan can be attached to it and handle thermal zones and RPM management in a generic manner. Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org> Link: https://lore.kernel.org/r/20250629220757.936212-3-marek.vasut+renesas@mailbox.org Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
109 lines
2.7 KiB
C
109 lines
2.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2025 Marek Vasut
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*
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* Limitations:
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* - no support for offset/polarity
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* - fixed 30 kHz period
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*
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* Argon Fan HAT https://argon40.com/products/argon-fan-hat
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*/
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#include <linux/err.h>
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#include <linux/i2c.h>
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#include <linux/module.h>
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#include <linux/pwm.h>
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#define ARGON40_FAN_HAT_PERIOD_NS 33333 /* ~30 kHz */
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#define ARGON40_FAN_HAT_REG_DUTY_CYCLE 0x80
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static int argon_fan_hat_round_waveform_tohw(struct pwm_chip *chip,
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struct pwm_device *pwm,
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const struct pwm_waveform *wf,
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void *_wfhw)
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{
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u8 *wfhw = _wfhw;
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if (wf->duty_length_ns > ARGON40_FAN_HAT_PERIOD_NS)
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*wfhw = 100;
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else
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*wfhw = mul_u64_u64_div_u64(wf->duty_length_ns, 100, ARGON40_FAN_HAT_PERIOD_NS);
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return 0;
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}
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static int argon_fan_hat_round_waveform_fromhw(struct pwm_chip *chip,
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struct pwm_device *pwm,
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const void *_wfhw,
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struct pwm_waveform *wf)
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{
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const u8 *wfhw = _wfhw;
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wf->period_length_ns = ARGON40_FAN_HAT_PERIOD_NS;
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wf->duty_length_ns = DIV64_U64_ROUND_UP(wf->period_length_ns * *wfhw, 100);
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wf->duty_offset_ns = 0;
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return 0;
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}
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static int argon_fan_hat_write_waveform(struct pwm_chip *chip,
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struct pwm_device *pwm,
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const void *_wfhw)
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{
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struct i2c_client *i2c = pwmchip_get_drvdata(chip);
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const u8 *wfhw = _wfhw;
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return i2c_smbus_write_byte_data(i2c, ARGON40_FAN_HAT_REG_DUTY_CYCLE, *wfhw);
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}
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static const struct pwm_ops argon_fan_hat_pwm_ops = {
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.sizeof_wfhw = sizeof(u8),
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.round_waveform_fromhw = argon_fan_hat_round_waveform_fromhw,
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.round_waveform_tohw = argon_fan_hat_round_waveform_tohw,
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.write_waveform = argon_fan_hat_write_waveform,
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/*
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* The controller does not provide any way to read info back,
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* reading from the controller stops the fan, therefore there
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* is no .read_waveform here.
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*/
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};
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static int argon_fan_hat_i2c_probe(struct i2c_client *i2c)
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{
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struct pwm_chip *chip = devm_pwmchip_alloc(&i2c->dev, 1, 0);
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int ret;
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if (IS_ERR(chip))
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return PTR_ERR(chip);
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chip->ops = &argon_fan_hat_pwm_ops;
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pwmchip_set_drvdata(chip, i2c);
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ret = devm_pwmchip_add(&i2c->dev, chip);
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if (ret)
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return dev_err_probe(&i2c->dev, ret, "Could not add PWM chip\n");
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return 0;
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}
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static const struct of_device_id argon_fan_hat_dt_ids[] = {
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{ .compatible = "argon40,fan-hat" },
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{ },
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};
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MODULE_DEVICE_TABLE(of, argon_fan_hat_dt_ids);
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static struct i2c_driver argon_fan_hat_driver = {
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.driver = {
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.name = "argon-fan-hat",
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.probe_type = PROBE_PREFER_ASYNCHRONOUS,
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.of_match_table = argon_fan_hat_dt_ids,
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},
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.probe = argon_fan_hat_i2c_probe,
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};
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module_i2c_driver(argon_fan_hat_driver);
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MODULE_AUTHOR("Marek Vasut <marek.vasut+renesas@mailbox.org>");
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MODULE_DESCRIPTION("Argon40 Fan HAT");
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MODULE_LICENSE("GPL");
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