pwm-fan.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * pwm-fan.c - Hwmon driver for fans connected to PWM lines.
  4 *
  5 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
  6 *
  7 * Author: Kamil Debski <k.debski@samsung.com>
  8 */
  9
 10#include <linux/delay.h>
 11#include <linux/hwmon.h>
 12#include <linux/interrupt.h>
 13#include <linux/mod_devicetable.h>
 14#include <linux/module.h>
 15#include <linux/mutex.h>
 16#include <linux/platform_device.h>
 17#include <linux/property.h>
 18#include <linux/pwm.h>
 19#include <linux/regulator/consumer.h>
 20#include <linux/sysfs.h>
 21#include <linux/thermal.h>
 22#include <linux/timer.h>
 23
 24#define MAX_PWM 255
 25
 26struct pwm_fan_tach {
 27	int irq;
 28	atomic_t pulses;
 29	unsigned int rpm;
 30};
 31
 32enum pwm_fan_enable_mode {
 33	pwm_off_reg_off,
 34	pwm_disable_reg_enable,
 35	pwm_enable_reg_enable,
 36	pwm_disable_reg_disable,
 37};
 38
 39struct pwm_fan_ctx {
 40	struct device *dev;
 41
 42	struct mutex lock;
 43	struct pwm_device *pwm;
 44	struct pwm_state pwm_state;
 45	struct regulator *reg_en;
 46	enum pwm_fan_enable_mode enable_mode;
 47	bool regulator_enabled;
 48	bool enabled;
 49
 50	int tach_count;
 51	struct pwm_fan_tach *tachs;
 52	u32 *pulses_per_revolution;
 53	ktime_t sample_start;
 54	struct timer_list rpm_timer;
 55
 56	unsigned int pwm_value;
 57	unsigned int pwm_fan_state;
 58	unsigned int pwm_fan_max_state;
 59	unsigned int *pwm_fan_cooling_levels;
 60	struct thermal_cooling_device *cdev;
 61
 62	struct hwmon_chip_info info;
 63	struct hwmon_channel_info fan_channel;
 64
 65	u64 pwm_duty_cycle_from_stopped;
 66	u32 pwm_usec_from_stopped;
 67	u8 pwm_shutdown;
 68};
 69
 70/* This handler assumes self resetting edge triggered interrupt. */
 71static irqreturn_t pulse_handler(int irq, void *dev_id)
 72{
 73	struct pwm_fan_tach *tach = dev_id;
 74
 75	atomic_inc(&tach->pulses);
 76
 77	return IRQ_HANDLED;
 78}
 79
 80static void sample_timer(struct timer_list *t)
 81{
 82	struct pwm_fan_ctx *ctx = timer_container_of(ctx, t, rpm_timer);
 83	unsigned int delta = ktime_ms_delta(ktime_get(), ctx->sample_start);
 84	int i;
 85
 86	if (delta) {
 87		for (i = 0; i < ctx->tach_count; i++) {
 88			struct pwm_fan_tach *tach = &ctx->tachs[i];
 89			int pulses;
 90
 91			pulses = atomic_read(&tach->pulses);
 92			atomic_sub(pulses, &tach->pulses);
 93			tach->rpm = (unsigned int)(pulses * 1000 * 60) /
 94				(ctx->pulses_per_revolution[i] * delta);
 95		}
 96
 97		ctx->sample_start = ktime_get();
 98	}
 99
100	mod_timer(&ctx->rpm_timer, jiffies + HZ);
101}
102
103static void pwm_fan_enable_mode_2_state(int enable_mode,
104					struct pwm_state *state,
105					bool *enable_regulator)
106{
107	switch (enable_mode) {
108	case pwm_disable_reg_enable:
109		/* disable pwm, keep regulator enabled */
110		state->enabled = false;
111		*enable_regulator = true;
112		break;
113	case pwm_enable_reg_enable:
114		/* keep pwm and regulator enabled */
115		state->enabled = true;
116		*enable_regulator = true;
117		break;
118	case pwm_off_reg_off:
119	case pwm_disable_reg_disable:
120		/* disable pwm and regulator */
121		state->enabled = false;
122		*enable_regulator = false;
123	}
124}
125
126static int pwm_fan_switch_power(struct pwm_fan_ctx *ctx, bool on)
127{
128	int ret = 0;
129
130	if (!ctx->reg_en)
131		return ret;
132
133	if (!ctx->regulator_enabled && on) {
134		ret = regulator_enable(ctx->reg_en);
135		if (ret == 0)
136			ctx->regulator_enabled = true;
137	} else if (ctx->regulator_enabled && !on) {
138		ret = regulator_disable(ctx->reg_en);
139		if (ret == 0)
140			ctx->regulator_enabled = false;
141	}
142	return ret;
143}
144
145static int pwm_fan_power_on(struct pwm_fan_ctx *ctx)
146{
147	struct pwm_state *state = &ctx->pwm_state;
148	int ret;
149
150	if (ctx->enabled)
151		return 0;
152
153	ret = pwm_fan_switch_power(ctx, true);
154	if (ret < 0) {
155		dev_err(ctx->dev, "failed to enable power supply\n");
156		return ret;
157	}
158
159	state->enabled = true;
160	ret = pwm_apply_might_sleep(ctx->pwm, state);
161	if (ret) {
162		dev_err(ctx->dev, "failed to enable PWM\n");
163		goto disable_regulator;
164	}
165
166	ctx->enabled = true;
167
168	return 0;
169
170disable_regulator:
171	pwm_fan_switch_power(ctx, false);
172	return ret;
173}
174
175static int pwm_fan_power_off(struct pwm_fan_ctx *ctx, bool force_disable)
176{
177	struct pwm_state *state = &ctx->pwm_state;
178	bool enable_regulator = false;
179	int ret;
180
181	if (!ctx->enabled)
182		return 0;
183
184	pwm_fan_enable_mode_2_state(ctx->enable_mode,
185				    state,
186				    &enable_regulator);
187
188	if (force_disable)
189		state->enabled = false;
190	state->duty_cycle = 0;
191	ret = pwm_apply_might_sleep(ctx->pwm, state);
192	if (ret) {
193		dev_err(ctx->dev, "failed to disable PWM\n");
194		return ret;
195	}
196
197	pwm_fan_switch_power(ctx, enable_regulator);
198
199	ctx->enabled = false;
200
201	return 0;
202}
203
204static int  __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
205{
206	struct pwm_state *state = &ctx->pwm_state;
207	unsigned long final_pwm = pwm;
208	unsigned long period;
209	bool update = false;
210	int ret = 0;
211
212	if (pwm > 0) {
213		if (ctx->enable_mode == pwm_off_reg_off)
214			/* pwm-fan hard disabled */
215			return 0;
216
217		period = state->period;
218		update = state->duty_cycle < ctx->pwm_duty_cycle_from_stopped;
219		if (update)
220			state->duty_cycle = ctx->pwm_duty_cycle_from_stopped;
221		else
222			state->duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM);
223		ret = pwm_apply_might_sleep(ctx->pwm, state);
224		if (ret)
225			return ret;
226		ret = pwm_fan_power_on(ctx);
227		if (!ret && update) {
228			pwm = final_pwm;
229			state->duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM);
230			usleep_range(ctx->pwm_usec_from_stopped,
231				     ctx->pwm_usec_from_stopped * 2);
232			ret = pwm_apply_might_sleep(ctx->pwm, state);
233		}
234	} else {
235		ret = pwm_fan_power_off(ctx, false);
236	}
237	if (!ret)
238		ctx->pwm_value = pwm;
239
240	return ret;
241}
242
243static int set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
244{
245	int ret;
246
247	mutex_lock(&ctx->lock);
248	ret = __set_pwm(ctx, pwm);
249	mutex_unlock(&ctx->lock);
250
251	return ret;
252}
253
254static void pwm_fan_update_state(struct pwm_fan_ctx *ctx, unsigned long pwm)
255{
256	int i;
257
258	for (i = 0; i < ctx->pwm_fan_max_state; ++i)
259		if (pwm < ctx->pwm_fan_cooling_levels[i + 1])
260			break;
261
262	ctx->pwm_fan_state = i;
263}
264
265static int pwm_fan_update_enable(struct pwm_fan_ctx *ctx, long val)
266{
267	int ret = 0;
268	int old_val;
269
270	mutex_lock(&ctx->lock);
271
272	if (ctx->enable_mode == val)
273		goto out;
274
275	old_val = ctx->enable_mode;
276	ctx->enable_mode = val;
277
278	if (val == 0) {
279		/* Disable pwm-fan unconditionally */
280		if (ctx->enabled)
281			ret = __set_pwm(ctx, 0);
282		else
283			ret = pwm_fan_switch_power(ctx, false);
284		if (ret)
285			ctx->enable_mode = old_val;
286		pwm_fan_update_state(ctx, 0);
287	} else {
288		/*
289		 * Change PWM and/or regulator state if currently disabled
290		 * Nothing to do if currently enabled
291		 */
292		if (!ctx->enabled) {
293			struct pwm_state *state = &ctx->pwm_state;
294			bool enable_regulator = false;
295
296			state->duty_cycle = 0;
297			pwm_fan_enable_mode_2_state(val,
298						    state,
299						    &enable_regulator);
300
301			pwm_apply_might_sleep(ctx->pwm, state);
302			pwm_fan_switch_power(ctx, enable_regulator);
303			pwm_fan_update_state(ctx, 0);
304		}
305	}
306out:
307	mutex_unlock(&ctx->lock);
308
309	return ret;
310}
311
312static int pwm_fan_write(struct device *dev, enum hwmon_sensor_types type,
313			 u32 attr, int channel, long val)
314{
315	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
316	int ret;
317
318	switch (attr) {
319	case hwmon_pwm_input:
320		if (val < 0 || val > MAX_PWM)
321			return -EINVAL;
322		ret = set_pwm(ctx, val);
323		if (ret)
324			return ret;
325		pwm_fan_update_state(ctx, val);
326		break;
327	case hwmon_pwm_enable:
328		if (val < 0 || val > 3)
329			ret = -EINVAL;
330		else
331			ret = pwm_fan_update_enable(ctx, val);
332
333		return ret;
334	default:
335		return -EOPNOTSUPP;
336	}
337
338	return 0;
339}
340
341static int pwm_fan_read(struct device *dev, enum hwmon_sensor_types type,
342			u32 attr, int channel, long *val)
343{
344	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
345
346	switch (type) {
347	case hwmon_pwm:
348		switch (attr) {
349		case hwmon_pwm_input:
350			*val = ctx->pwm_value;
351			return 0;
352		case hwmon_pwm_enable:
353			*val = ctx->enable_mode;
354			return 0;
355		}
356		return -EOPNOTSUPP;
357	case hwmon_fan:
358		*val = ctx->tachs[channel].rpm;
359		return 0;
360
361	default:
362		return -ENOTSUPP;
363	}
364}
365
366static umode_t pwm_fan_is_visible(const void *data,
367				  enum hwmon_sensor_types type,
368				  u32 attr, int channel)
369{
370	switch (type) {
371	case hwmon_pwm:
372		return 0644;
373
374	case hwmon_fan:
375		return 0444;
376
377	default:
378		return 0;
379	}
380}
381
382static const struct hwmon_ops pwm_fan_hwmon_ops = {
383	.is_visible = pwm_fan_is_visible,
384	.read = pwm_fan_read,
385	.write = pwm_fan_write,
386};
387
388/* thermal cooling device callbacks */
389static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
390				 unsigned long *state)
391{
392	struct pwm_fan_ctx *ctx = cdev->devdata;
393
394	if (!ctx)
395		return -EINVAL;
396
397	*state = ctx->pwm_fan_max_state;
398
399	return 0;
400}
401
402static int pwm_fan_get_cur_state(struct thermal_cooling_device *cdev,
403				 unsigned long *state)
404{
405	struct pwm_fan_ctx *ctx = cdev->devdata;
406
407	if (!ctx)
408		return -EINVAL;
409
410	*state = ctx->pwm_fan_state;
411
412	return 0;
413}
414
415static int
416pwm_fan_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
417{
418	struct pwm_fan_ctx *ctx = cdev->devdata;
419	int ret;
420
421	if (!ctx || (state > ctx->pwm_fan_max_state))
422		return -EINVAL;
423
424	if (state == ctx->pwm_fan_state)
425		return 0;
426
427	ret = set_pwm(ctx, ctx->pwm_fan_cooling_levels[state]);
428	if (ret) {
429		dev_err(&cdev->device, "Cannot set pwm!\n");
430		return ret;
431	}
432
433	ctx->pwm_fan_state = state;
434
435	return ret;
436}
437
438static const struct thermal_cooling_device_ops pwm_fan_cooling_ops = {
439	.get_max_state = pwm_fan_get_max_state,
440	.get_cur_state = pwm_fan_get_cur_state,
441	.set_cur_state = pwm_fan_set_cur_state,
442};
443
444static int pwm_fan_get_cooling_data(struct device *dev, struct pwm_fan_ctx *ctx)
445{
446	int num, i, ret;
447
448	if (!device_property_present(dev, "cooling-levels"))
449		return 0;
450
451	ret = device_property_count_u32(dev, "cooling-levels");
452	if (ret <= 0) {
453		dev_err(dev, "Wrong data!\n");
454		return ret ? : -EINVAL;
455	}
456
457	num = ret;
458	ctx->pwm_fan_cooling_levels = devm_kcalloc(dev, num, sizeof(u32),
459						   GFP_KERNEL);
460	if (!ctx->pwm_fan_cooling_levels)
461		return -ENOMEM;
462
463	ret = device_property_read_u32_array(dev, "cooling-levels",
464					     ctx->pwm_fan_cooling_levels, num);
465	if (ret) {
466		dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
467		return ret;
468	}
469
470	for (i = 0; i < num; i++) {
471		if (ctx->pwm_fan_cooling_levels[i] > MAX_PWM) {
472			dev_err(dev, "PWM fan state[%d]:%d > %d\n", i,
473				ctx->pwm_fan_cooling_levels[i], MAX_PWM);
474			return -EINVAL;
475		}
476	}
477
478	ctx->pwm_fan_max_state = num - 1;
479
480	return 0;
481}
482
483static void pwm_fan_cleanup(void *__ctx)
484{
485	struct pwm_fan_ctx *ctx = __ctx;
486
487	timer_delete_sync(&ctx->rpm_timer);
488	if (ctx->pwm_shutdown) {
489		ctx->enable_mode = pwm_enable_reg_enable;
490		__set_pwm(ctx, ctx->pwm_shutdown);
491	} else {
492		/* Switch off everything */
493		ctx->enable_mode = pwm_disable_reg_disable;
494		pwm_fan_power_off(ctx, true);
495	}
496}
497
498static int pwm_fan_probe(struct platform_device *pdev)
499{
500	struct thermal_cooling_device *cdev;
501	struct device *dev = &pdev->dev;
502	struct pwm_fan_ctx *ctx;
503	struct device *hwmon;
504	int ret;
505	const struct hwmon_channel_info **channels;
506	u32 initial_pwm, pwm_min_from_stopped = 0;
507	u32 pwm_shutdown_percent = 0;
508	u32 *fan_channel_config;
509	int channel_count = 1;	/* We always have a PWM channel. */
510	int i;
511
512	ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
513	if (!ctx)
514		return -ENOMEM;
515
516	mutex_init(&ctx->lock);
517
518	ctx->dev = &pdev->dev;
519	ctx->pwm = devm_pwm_get(dev, NULL);
520	if (IS_ERR(ctx->pwm))
521		return dev_err_probe(dev, PTR_ERR(ctx->pwm), "Could not get PWM\n");
522
523	platform_set_drvdata(pdev, ctx);
524
525	ctx->reg_en = devm_regulator_get_optional(dev, "fan");
526	if (IS_ERR(ctx->reg_en)) {
527		if (PTR_ERR(ctx->reg_en) != -ENODEV)
528			return PTR_ERR(ctx->reg_en);
529
530		ctx->reg_en = NULL;
531	}
532
533	pwm_init_state(ctx->pwm, &ctx->pwm_state);
534
535	/*
536	 * PWM fans are controlled solely by the duty cycle of the PWM signal,
537	 * they do not care about the exact timing. Thus set usage_power to true
538	 * to allow less flexible hardware to work as a PWM source for fan
539	 * control.
540	 */
541	ctx->pwm_state.usage_power = true;
542
543	/*
544	 * set_pwm assumes that MAX_PWM * (period - 1) fits into an unsigned
545	 * long. Check this here to prevent the fan running at a too low
546	 * frequency.
547	 */
548	if (ctx->pwm_state.period > ULONG_MAX / MAX_PWM + 1) {
549		dev_err(dev, "Configured period too big\n");
550		return -EINVAL;
551	}
552
553	ctx->enable_mode = pwm_disable_reg_enable;
554
555	ret = pwm_fan_get_cooling_data(dev, ctx);
556	if (ret)
557		return ret;
558
559	/* use maximum cooling level if provided */
560	if (ctx->pwm_fan_cooling_levels)
561		initial_pwm = ctx->pwm_fan_cooling_levels[ctx->pwm_fan_max_state];
562	else
563		initial_pwm = MAX_PWM;
564
565	/*
566	 * Set duty cycle to maximum allowed and enable PWM output as well as
567	 * the regulator. In case of error nothing is changed
568	 */
569	ret = set_pwm(ctx, initial_pwm);
570	if (ret) {
571		dev_err(dev, "Failed to configure PWM: %d\n", ret);
572		return ret;
573	}
574	timer_setup(&ctx->rpm_timer, sample_timer, 0);
575	ret = devm_add_action_or_reset(dev, pwm_fan_cleanup, ctx);
576	if (ret)
577		return ret;
578
579	ctx->tach_count = platform_irq_count(pdev);
580	if (ctx->tach_count < 0)
581		return dev_err_probe(dev, ctx->tach_count,
582				     "Could not get number of fan tachometer inputs\n");
583	dev_dbg(dev, "%d fan tachometer inputs\n", ctx->tach_count);
584
585	if (ctx->tach_count) {
586		channel_count++;	/* We also have a FAN channel. */
587
588		ctx->tachs = devm_kcalloc(dev, ctx->tach_count,
589					  sizeof(struct pwm_fan_tach),
590					  GFP_KERNEL);
591		if (!ctx->tachs)
592			return -ENOMEM;
593
594		ctx->fan_channel.type = hwmon_fan;
595		fan_channel_config = devm_kcalloc(dev, ctx->tach_count + 1,
596						  sizeof(u32), GFP_KERNEL);
597		if (!fan_channel_config)
598			return -ENOMEM;
599		ctx->fan_channel.config = fan_channel_config;
600
601		ctx->pulses_per_revolution = devm_kmalloc_array(dev,
602								ctx->tach_count,
603								sizeof(*ctx->pulses_per_revolution),
604								GFP_KERNEL);
605		if (!ctx->pulses_per_revolution)
606			return -ENOMEM;
607
608		/* Setup default pulses per revolution */
609		for (i = 0; i < ctx->tach_count; i++)
610			ctx->pulses_per_revolution[i] = 2;
611
612		device_property_read_u32_array(dev, "pulses-per-revolution",
613					       ctx->pulses_per_revolution, ctx->tach_count);
614	}
615
616	channels = devm_kcalloc(dev, channel_count + 1,
617				sizeof(struct hwmon_channel_info *), GFP_KERNEL);
618	if (!channels)
619		return -ENOMEM;
620
621	channels[0] = HWMON_CHANNEL_INFO(pwm, HWMON_PWM_INPUT | HWMON_PWM_ENABLE);
622
623	for (i = 0; i < ctx->tach_count; i++) {
624		struct pwm_fan_tach *tach = &ctx->tachs[i];
625
626		tach->irq = platform_get_irq(pdev, i);
627		if (tach->irq == -EPROBE_DEFER)
628			return tach->irq;
629		if (tach->irq > 0) {
630			ret = devm_request_irq(dev, tach->irq, pulse_handler,
631					       IRQF_NO_THREAD, pdev->name, tach);
632			if (ret) {
633				dev_err(dev,
634					"Failed to request interrupt: %d\n",
635					ret);
636				return ret;
637			}
638		}
639
640		if (!ctx->pulses_per_revolution[i]) {
641			dev_err(dev, "pulses-per-revolution can't be zero.\n");
642			return -EINVAL;
643		}
644
645		fan_channel_config[i] = HWMON_F_INPUT;
646
647		dev_dbg(dev, "tach%d: irq=%d, pulses_per_revolution=%d\n",
648			i, tach->irq, ctx->pulses_per_revolution[i]);
649	}
650
651	if (ctx->tach_count > 0) {
652		ctx->sample_start = ktime_get();
653		mod_timer(&ctx->rpm_timer, jiffies + HZ);
654
655		channels[1] = &ctx->fan_channel;
656	}
657
658	ret = device_property_read_u32(dev, "fan-shutdown-percent",
659				       &pwm_shutdown_percent);
660	if (!ret && pwm_shutdown_percent)
661		ctx->pwm_shutdown = (clamp(pwm_shutdown_percent, 0, 100) * 255) / 100;
662
663	ret = device_property_read_u32(dev, "fan-stop-to-start-percent",
664				       &pwm_min_from_stopped);
665	if (!ret && pwm_min_from_stopped) {
666		ctx->pwm_duty_cycle_from_stopped =
667			DIV_ROUND_UP_ULL(pwm_min_from_stopped *
668					 (ctx->pwm_state.period - 1),
669					 100);
670	}
671	ret = device_property_read_u32(dev, "fan-stop-to-start-us",
672				       &ctx->pwm_usec_from_stopped);
673	if (ret)
674		ctx->pwm_usec_from_stopped = 250000;
675
676	ctx->info.ops = &pwm_fan_hwmon_ops;
677	ctx->info.info = channels;
678
679	hwmon = devm_hwmon_device_register_with_info(dev, "pwmfan",
680						     ctx, &ctx->info, NULL);
681	if (IS_ERR(hwmon)) {
682		dev_err(dev, "Failed to register hwmon device\n");
683		return PTR_ERR(hwmon);
684	}
685
686	ctx->pwm_fan_state = ctx->pwm_fan_max_state;
687	if (IS_ENABLED(CONFIG_THERMAL)) {
688		cdev = devm_thermal_of_cooling_device_register(dev,
689			dev->of_node, "pwm-fan", ctx, &pwm_fan_cooling_ops);
690		if (IS_ERR(cdev)) {
691			ret = PTR_ERR(cdev);
692			dev_err(dev,
693				"Failed to register pwm-fan as cooling device: %d\n",
694				ret);
695			return ret;
696		}
697		ctx->cdev = cdev;
698	}
699
700	return 0;
701}
702
703static void pwm_fan_shutdown(struct platform_device *pdev)
704{
705	struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev);
706
707	pwm_fan_cleanup(ctx);
708}
709
710static int pwm_fan_suspend(struct device *dev)
711{
712	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
713
714	return pwm_fan_power_off(ctx, true);
715}
716
717static int pwm_fan_resume(struct device *dev)
718{
719	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
720
721	return set_pwm(ctx, ctx->pwm_value);
722}
723
724static DEFINE_SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume);
725
726static const struct of_device_id of_pwm_fan_match[] = {
727	{ .compatible = "pwm-fan", },
728	{},
729};
730MODULE_DEVICE_TABLE(of, of_pwm_fan_match);
731
732static struct platform_driver pwm_fan_driver = {
733	.probe		= pwm_fan_probe,
734	.shutdown	= pwm_fan_shutdown,
735	.driver	= {
736		.name		= "pwm-fan",
737		.pm		= pm_sleep_ptr(&pwm_fan_pm),
738		.of_match_table	= of_pwm_fan_match,
739	},
740};
741
742module_platform_driver(pwm_fan_driver);
743
744MODULE_AUTHOR("Kamil Debski <k.debski@samsung.com>");
745MODULE_ALIAS("platform:pwm-fan");
746MODULE_DESCRIPTION("PWM FAN driver");
747MODULE_LICENSE("GPL");