1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * pwm-fan.c - Hwmon driver for fans connected to PWM lines.
5 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
7 * Author: Kamil Debski <k.debski@samsung.com>
10 #include <linux/hwmon.h>
11 #include <linux/interrupt.h>
12 #include <linux/module.h>
13 #include <linux/mutex.h>
15 #include <linux/platform_device.h>
16 #include <linux/pwm.h>
17 #include <linux/regulator/consumer.h>
18 #include <linux/sysfs.h>
19 #include <linux/thermal.h>
20 #include <linux/timer.h>
28 u8 pulses_per_revolution;
31 enum pwm_fan_enable_mode {
33 pwm_disable_reg_enable,
34 pwm_enable_reg_enable,
35 pwm_disable_reg_disable,
42 struct pwm_device *pwm;
43 struct pwm_state pwm_state;
44 struct regulator *reg_en;
45 enum pwm_fan_enable_mode enable_mode;
46 bool regulator_enabled;
50 struct pwm_fan_tach *tachs;
52 struct timer_list rpm_timer;
54 unsigned int pwm_value;
55 unsigned int pwm_fan_state;
56 unsigned int pwm_fan_max_state;
57 unsigned int *pwm_fan_cooling_levels;
58 struct thermal_cooling_device *cdev;
60 struct hwmon_chip_info info;
61 struct hwmon_channel_info fan_channel;
64 /* This handler assumes self resetting edge triggered interrupt. */
65 static irqreturn_t pulse_handler(int irq, void *dev_id)
67 struct pwm_fan_tach *tach = dev_id;
69 atomic_inc(&tach->pulses);
74 static void sample_timer(struct timer_list *t)
76 struct pwm_fan_ctx *ctx = from_timer(ctx, t, rpm_timer);
77 unsigned int delta = ktime_ms_delta(ktime_get(), ctx->sample_start);
81 for (i = 0; i < ctx->tach_count; i++) {
82 struct pwm_fan_tach *tach = &ctx->tachs[i];
85 pulses = atomic_read(&tach->pulses);
86 atomic_sub(pulses, &tach->pulses);
87 tach->rpm = (unsigned int)(pulses * 1000 * 60) /
88 (tach->pulses_per_revolution * delta);
91 ctx->sample_start = ktime_get();
94 mod_timer(&ctx->rpm_timer, jiffies + HZ);
97 static void pwm_fan_enable_mode_2_state(int enable_mode,
98 struct pwm_state *state,
99 bool *enable_regulator)
101 switch (enable_mode) {
102 case pwm_disable_reg_enable:
103 /* disable pwm, keep regulator enabled */
104 state->enabled = false;
105 *enable_regulator = true;
107 case pwm_enable_reg_enable:
108 /* keep pwm and regulator enabled */
109 state->enabled = true;
110 *enable_regulator = true;
112 case pwm_off_reg_off:
113 case pwm_disable_reg_disable:
114 /* disable pwm and regulator */
115 state->enabled = false;
116 *enable_regulator = false;
120 static int pwm_fan_switch_power(struct pwm_fan_ctx *ctx, bool on)
127 if (!ctx->regulator_enabled && on) {
128 ret = regulator_enable(ctx->reg_en);
130 ctx->regulator_enabled = true;
131 } else if (ctx->regulator_enabled && !on) {
132 ret = regulator_disable(ctx->reg_en);
134 ctx->regulator_enabled = false;
139 static int pwm_fan_power_on(struct pwm_fan_ctx *ctx)
141 struct pwm_state *state = &ctx->pwm_state;
147 ret = pwm_fan_switch_power(ctx, true);
149 dev_err(ctx->dev, "failed to enable power supply\n");
153 state->enabled = true;
154 ret = pwm_apply_state(ctx->pwm, state);
156 dev_err(ctx->dev, "failed to enable PWM\n");
157 goto disable_regulator;
165 pwm_fan_switch_power(ctx, false);
169 static int pwm_fan_power_off(struct pwm_fan_ctx *ctx)
171 struct pwm_state *state = &ctx->pwm_state;
172 bool enable_regulator = false;
178 pwm_fan_enable_mode_2_state(ctx->enable_mode,
182 state->enabled = false;
183 state->duty_cycle = 0;
184 ret = pwm_apply_state(ctx->pwm, state);
186 dev_err(ctx->dev, "failed to disable PWM\n");
190 pwm_fan_switch_power(ctx, enable_regulator);
192 ctx->enabled = false;
197 static int __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
199 struct pwm_state *state = &ctx->pwm_state;
200 unsigned long period;
204 if (ctx->enable_mode == pwm_off_reg_off)
205 /* pwm-fan hard disabled */
208 period = state->period;
209 state->duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM);
210 ret = pwm_apply_state(ctx->pwm, state);
213 ret = pwm_fan_power_on(ctx);
215 ret = pwm_fan_power_off(ctx);
218 ctx->pwm_value = pwm;
223 static int set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
227 mutex_lock(&ctx->lock);
228 ret = __set_pwm(ctx, pwm);
229 mutex_unlock(&ctx->lock);
234 static void pwm_fan_update_state(struct pwm_fan_ctx *ctx, unsigned long pwm)
238 for (i = 0; i < ctx->pwm_fan_max_state; ++i)
239 if (pwm < ctx->pwm_fan_cooling_levels[i + 1])
242 ctx->pwm_fan_state = i;
245 static int pwm_fan_update_enable(struct pwm_fan_ctx *ctx, long val)
250 mutex_lock(&ctx->lock);
252 if (ctx->enable_mode == val)
255 old_val = ctx->enable_mode;
256 ctx->enable_mode = val;
259 /* Disable pwm-fan unconditionally */
261 ret = __set_pwm(ctx, 0);
263 ret = pwm_fan_switch_power(ctx, false);
265 ctx->enable_mode = old_val;
266 pwm_fan_update_state(ctx, 0);
269 * Change PWM and/or regulator state if currently disabled
270 * Nothing to do if currently enabled
273 struct pwm_state *state = &ctx->pwm_state;
274 bool enable_regulator = false;
276 state->duty_cycle = 0;
277 pwm_fan_enable_mode_2_state(val,
281 pwm_apply_state(ctx->pwm, state);
282 pwm_fan_switch_power(ctx, enable_regulator);
283 pwm_fan_update_state(ctx, 0);
287 mutex_unlock(&ctx->lock);
292 static int pwm_fan_write(struct device *dev, enum hwmon_sensor_types type,
293 u32 attr, int channel, long val)
295 struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
299 case hwmon_pwm_input:
300 if (val < 0 || val > MAX_PWM)
302 ret = set_pwm(ctx, val);
305 pwm_fan_update_state(ctx, val);
307 case hwmon_pwm_enable:
308 if (val < 0 || val > 3)
311 ret = pwm_fan_update_enable(ctx, val);
321 static int pwm_fan_read(struct device *dev, enum hwmon_sensor_types type,
322 u32 attr, int channel, long *val)
324 struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
329 case hwmon_pwm_input:
330 *val = ctx->pwm_value;
332 case hwmon_pwm_enable:
333 *val = ctx->enable_mode;
338 *val = ctx->tachs[channel].rpm;
346 static umode_t pwm_fan_is_visible(const void *data,
347 enum hwmon_sensor_types type,
348 u32 attr, int channel)
362 static const struct hwmon_ops pwm_fan_hwmon_ops = {
363 .is_visible = pwm_fan_is_visible,
364 .read = pwm_fan_read,
365 .write = pwm_fan_write,
368 /* thermal cooling device callbacks */
369 static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
370 unsigned long *state)
372 struct pwm_fan_ctx *ctx = cdev->devdata;
377 *state = ctx->pwm_fan_max_state;
382 static int pwm_fan_get_cur_state(struct thermal_cooling_device *cdev,
383 unsigned long *state)
385 struct pwm_fan_ctx *ctx = cdev->devdata;
390 *state = ctx->pwm_fan_state;
396 pwm_fan_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
398 struct pwm_fan_ctx *ctx = cdev->devdata;
401 if (!ctx || (state > ctx->pwm_fan_max_state))
404 if (state == ctx->pwm_fan_state)
407 ret = set_pwm(ctx, ctx->pwm_fan_cooling_levels[state]);
409 dev_err(&cdev->device, "Cannot set pwm!\n");
413 ctx->pwm_fan_state = state;
418 static const struct thermal_cooling_device_ops pwm_fan_cooling_ops = {
419 .get_max_state = pwm_fan_get_max_state,
420 .get_cur_state = pwm_fan_get_cur_state,
421 .set_cur_state = pwm_fan_set_cur_state,
424 static int pwm_fan_of_get_cooling_data(struct device *dev,
425 struct pwm_fan_ctx *ctx)
427 struct device_node *np = dev->of_node;
430 if (!of_find_property(np, "cooling-levels", NULL))
433 ret = of_property_count_u32_elems(np, "cooling-levels");
435 dev_err(dev, "Wrong data!\n");
436 return ret ? : -EINVAL;
440 ctx->pwm_fan_cooling_levels = devm_kcalloc(dev, num, sizeof(u32),
442 if (!ctx->pwm_fan_cooling_levels)
445 ret = of_property_read_u32_array(np, "cooling-levels",
446 ctx->pwm_fan_cooling_levels, num);
448 dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
452 for (i = 0; i < num; i++) {
453 if (ctx->pwm_fan_cooling_levels[i] > MAX_PWM) {
454 dev_err(dev, "PWM fan state[%d]:%d > %d\n", i,
455 ctx->pwm_fan_cooling_levels[i], MAX_PWM);
460 ctx->pwm_fan_max_state = num - 1;
465 static void pwm_fan_cleanup(void *__ctx)
467 struct pwm_fan_ctx *ctx = __ctx;
469 del_timer_sync(&ctx->rpm_timer);
470 /* Switch off everything */
471 ctx->enable_mode = pwm_disable_reg_disable;
472 pwm_fan_power_off(ctx);
475 static int pwm_fan_probe(struct platform_device *pdev)
477 struct thermal_cooling_device *cdev;
478 struct device *dev = &pdev->dev;
479 struct pwm_fan_ctx *ctx;
480 struct device *hwmon;
482 const struct hwmon_channel_info **channels;
483 u32 *fan_channel_config;
484 int channel_count = 1; /* We always have a PWM channel. */
487 ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
491 mutex_init(&ctx->lock);
493 ctx->dev = &pdev->dev;
494 ctx->pwm = devm_pwm_get(dev, NULL);
495 if (IS_ERR(ctx->pwm))
496 return dev_err_probe(dev, PTR_ERR(ctx->pwm), "Could not get PWM\n");
498 platform_set_drvdata(pdev, ctx);
500 ctx->reg_en = devm_regulator_get_optional(dev, "fan");
501 if (IS_ERR(ctx->reg_en)) {
502 if (PTR_ERR(ctx->reg_en) != -ENODEV)
503 return PTR_ERR(ctx->reg_en);
508 pwm_init_state(ctx->pwm, &ctx->pwm_state);
511 * set_pwm assumes that MAX_PWM * (period - 1) fits into an unsigned
512 * long. Check this here to prevent the fan running at a too low
515 if (ctx->pwm_state.period > ULONG_MAX / MAX_PWM + 1) {
516 dev_err(dev, "Configured period too big\n");
520 ctx->enable_mode = pwm_disable_reg_enable;
523 * Set duty cycle to maximum allowed and enable PWM output as well as
524 * the regulator. In case of error nothing is changed
526 ret = set_pwm(ctx, MAX_PWM);
528 dev_err(dev, "Failed to configure PWM: %d\n", ret);
531 timer_setup(&ctx->rpm_timer, sample_timer, 0);
532 ret = devm_add_action_or_reset(dev, pwm_fan_cleanup, ctx);
536 ctx->tach_count = platform_irq_count(pdev);
537 if (ctx->tach_count < 0)
538 return dev_err_probe(dev, ctx->tach_count,
539 "Could not get number of fan tachometer inputs\n");
540 dev_dbg(dev, "%d fan tachometer inputs\n", ctx->tach_count);
542 if (ctx->tach_count) {
543 channel_count++; /* We also have a FAN channel. */
545 ctx->tachs = devm_kcalloc(dev, ctx->tach_count,
546 sizeof(struct pwm_fan_tach),
551 ctx->fan_channel.type = hwmon_fan;
552 fan_channel_config = devm_kcalloc(dev, ctx->tach_count + 1,
553 sizeof(u32), GFP_KERNEL);
554 if (!fan_channel_config)
556 ctx->fan_channel.config = fan_channel_config;
559 channels = devm_kcalloc(dev, channel_count + 1,
560 sizeof(struct hwmon_channel_info *), GFP_KERNEL);
564 channels[0] = HWMON_CHANNEL_INFO(pwm, HWMON_PWM_INPUT | HWMON_PWM_ENABLE);
566 for (i = 0; i < ctx->tach_count; i++) {
567 struct pwm_fan_tach *tach = &ctx->tachs[i];
570 tach->irq = platform_get_irq(pdev, i);
571 if (tach->irq == -EPROBE_DEFER)
574 ret = devm_request_irq(dev, tach->irq, pulse_handler, 0,
578 "Failed to request interrupt: %d\n",
584 of_property_read_u32_index(dev->of_node,
585 "pulses-per-revolution",
588 tach->pulses_per_revolution = ppr;
589 if (!tach->pulses_per_revolution) {
590 dev_err(dev, "pulses-per-revolution can't be zero.\n");
594 fan_channel_config[i] = HWMON_F_INPUT;
596 dev_dbg(dev, "tach%d: irq=%d, pulses_per_revolution=%d\n",
597 i, tach->irq, tach->pulses_per_revolution);
600 if (ctx->tach_count > 0) {
601 ctx->sample_start = ktime_get();
602 mod_timer(&ctx->rpm_timer, jiffies + HZ);
604 channels[1] = &ctx->fan_channel;
607 ctx->info.ops = &pwm_fan_hwmon_ops;
608 ctx->info.info = channels;
610 hwmon = devm_hwmon_device_register_with_info(dev, "pwmfan",
611 ctx, &ctx->info, NULL);
613 dev_err(dev, "Failed to register hwmon device\n");
614 return PTR_ERR(hwmon);
617 ret = pwm_fan_of_get_cooling_data(dev, ctx);
621 ctx->pwm_fan_state = ctx->pwm_fan_max_state;
622 if (IS_ENABLED(CONFIG_THERMAL)) {
623 cdev = devm_thermal_of_cooling_device_register(dev,
624 dev->of_node, "pwm-fan", ctx, &pwm_fan_cooling_ops);
628 "Failed to register pwm-fan as cooling device: %d\n",
638 static void pwm_fan_shutdown(struct platform_device *pdev)
640 struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev);
642 pwm_fan_cleanup(ctx);
645 static int pwm_fan_suspend(struct device *dev)
647 struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
649 return pwm_fan_power_off(ctx);
652 static int pwm_fan_resume(struct device *dev)
654 struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
656 return set_pwm(ctx, ctx->pwm_value);
659 static DEFINE_SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume);
661 static const struct of_device_id of_pwm_fan_match[] = {
662 { .compatible = "pwm-fan", },
665 MODULE_DEVICE_TABLE(of, of_pwm_fan_match);
667 static struct platform_driver pwm_fan_driver = {
668 .probe = pwm_fan_probe,
669 .shutdown = pwm_fan_shutdown,
672 .pm = pm_sleep_ptr(&pwm_fan_pm),
673 .of_match_table = of_pwm_fan_match,
677 module_platform_driver(pwm_fan_driver);
679 MODULE_AUTHOR("Kamil Debski <k.debski@samsung.com>");
680 MODULE_ALIAS("platform:pwm-fan");
681 MODULE_DESCRIPTION("PWM FAN driver");
682 MODULE_LICENSE("GPL");