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