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/hwmon-sysfs.h>
12 #include <linux/interrupt.h>
13 #include <linux/module.h>
14 #include <linux/mutex.h>
15 #include <linux/of.h>
16 #include <linux/platform_device.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_ctx {
26 struct mutex lock;
27 struct pwm_device *pwm;
28 struct regulator *reg_en;
29
30 int irq;
31 atomic_t pulses;
32 unsigned int rpm;
33 u8 pulses_per_revolution;
34 ktime_t sample_start;
35 struct timer_list rpm_timer;
36
37 unsigned int pwm_value;
38 unsigned int pwm_fan_state;
39 unsigned int pwm_fan_max_state;
40 unsigned int *pwm_fan_cooling_levels;
41 struct thermal_cooling_device *cdev;
42 };
43
44 /* This handler assumes self resetting edge triggered interrupt. */
pulse_handler(int irq,void * dev_id)45 static irqreturn_t pulse_handler(int irq, void *dev_id)
46 {
47 struct pwm_fan_ctx *ctx = dev_id;
48
49 atomic_inc(&ctx->pulses);
50
51 return IRQ_HANDLED;
52 }
53
sample_timer(struct timer_list * t)54 static void sample_timer(struct timer_list *t)
55 {
56 struct pwm_fan_ctx *ctx = from_timer(ctx, t, rpm_timer);
57 unsigned int delta = ktime_ms_delta(ktime_get(), ctx->sample_start);
58 int pulses;
59
60 if (delta) {
61 pulses = atomic_read(&ctx->pulses);
62 atomic_sub(pulses, &ctx->pulses);
63 ctx->rpm = (unsigned int)(pulses * 1000 * 60) /
64 (ctx->pulses_per_revolution * delta);
65
66 ctx->sample_start = ktime_get();
67 }
68
69 mod_timer(&ctx->rpm_timer, jiffies + HZ);
70 }
71
__set_pwm(struct pwm_fan_ctx * ctx,unsigned long pwm)72 static int __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
73 {
74 unsigned long period;
75 int ret = 0;
76 struct pwm_state state = { };
77
78 mutex_lock(&ctx->lock);
79 if (ctx->pwm_value == pwm)
80 goto exit_set_pwm_err;
81
82 pwm_init_state(ctx->pwm, &state);
83 period = ctx->pwm->args.period;
84 state.duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM);
85 state.enabled = pwm ? true : false;
86
87 ret = pwm_apply_state(ctx->pwm, &state);
88 if (!ret)
89 ctx->pwm_value = pwm;
90 exit_set_pwm_err:
91 mutex_unlock(&ctx->lock);
92 return ret;
93 }
94
pwm_fan_update_state(struct pwm_fan_ctx * ctx,unsigned long pwm)95 static void pwm_fan_update_state(struct pwm_fan_ctx *ctx, unsigned long pwm)
96 {
97 int i;
98
99 for (i = 0; i < ctx->pwm_fan_max_state; ++i)
100 if (pwm < ctx->pwm_fan_cooling_levels[i + 1])
101 break;
102
103 ctx->pwm_fan_state = i;
104 }
105
pwm_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)106 static ssize_t pwm_store(struct device *dev, struct device_attribute *attr,
107 const char *buf, size_t count)
108 {
109 struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
110 unsigned long pwm;
111 int ret;
112
113 if (kstrtoul(buf, 10, &pwm) || pwm > MAX_PWM)
114 return -EINVAL;
115
116 ret = __set_pwm(ctx, pwm);
117 if (ret)
118 return ret;
119
120 pwm_fan_update_state(ctx, pwm);
121 return count;
122 }
123
pwm_show(struct device * dev,struct device_attribute * attr,char * buf)124 static ssize_t pwm_show(struct device *dev, struct device_attribute *attr,
125 char *buf)
126 {
127 struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
128
129 return sprintf(buf, "%u\n", ctx->pwm_value);
130 }
131
rpm_show(struct device * dev,struct device_attribute * attr,char * buf)132 static ssize_t rpm_show(struct device *dev,
133 struct device_attribute *attr, char *buf)
134 {
135 struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
136
137 return sprintf(buf, "%u\n", ctx->rpm);
138 }
139
140 static SENSOR_DEVICE_ATTR_RW(pwm1, pwm, 0);
141 static SENSOR_DEVICE_ATTR_RO(fan1_input, rpm, 0);
142
143 static struct attribute *pwm_fan_attrs[] = {
144 &sensor_dev_attr_pwm1.dev_attr.attr,
145 &sensor_dev_attr_fan1_input.dev_attr.attr,
146 NULL,
147 };
148
pwm_fan_attrs_visible(struct kobject * kobj,struct attribute * a,int n)149 static umode_t pwm_fan_attrs_visible(struct kobject *kobj, struct attribute *a,
150 int n)
151 {
152 struct device *dev = container_of(kobj, struct device, kobj);
153 struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
154
155 /* Hide fan_input in case no interrupt is available */
156 if (n == 1 && ctx->irq <= 0)
157 return 0;
158
159 return a->mode;
160 }
161
162 static const struct attribute_group pwm_fan_group = {
163 .attrs = pwm_fan_attrs,
164 .is_visible = pwm_fan_attrs_visible,
165 };
166
167 static const struct attribute_group *pwm_fan_groups[] = {
168 &pwm_fan_group,
169 NULL,
170 };
171
172 /* thermal cooling device callbacks */
pwm_fan_get_max_state(struct thermal_cooling_device * cdev,unsigned long * state)173 static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
174 unsigned long *state)
175 {
176 struct pwm_fan_ctx *ctx = cdev->devdata;
177
178 if (!ctx)
179 return -EINVAL;
180
181 *state = ctx->pwm_fan_max_state;
182
183 return 0;
184 }
185
pwm_fan_get_cur_state(struct thermal_cooling_device * cdev,unsigned long * state)186 static int pwm_fan_get_cur_state(struct thermal_cooling_device *cdev,
187 unsigned long *state)
188 {
189 struct pwm_fan_ctx *ctx = cdev->devdata;
190
191 if (!ctx)
192 return -EINVAL;
193
194 *state = ctx->pwm_fan_state;
195
196 return 0;
197 }
198
199 static int
pwm_fan_set_cur_state(struct thermal_cooling_device * cdev,unsigned long state)200 pwm_fan_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
201 {
202 struct pwm_fan_ctx *ctx = cdev->devdata;
203 int ret;
204
205 if (!ctx || (state > ctx->pwm_fan_max_state))
206 return -EINVAL;
207
208 if (state == ctx->pwm_fan_state)
209 return 0;
210
211 ret = __set_pwm(ctx, ctx->pwm_fan_cooling_levels[state]);
212 if (ret) {
213 dev_err(&cdev->device, "Cannot set pwm!\n");
214 return ret;
215 }
216
217 ctx->pwm_fan_state = state;
218
219 return ret;
220 }
221
222 static const struct thermal_cooling_device_ops pwm_fan_cooling_ops = {
223 .get_max_state = pwm_fan_get_max_state,
224 .get_cur_state = pwm_fan_get_cur_state,
225 .set_cur_state = pwm_fan_set_cur_state,
226 };
227
pwm_fan_of_get_cooling_data(struct device * dev,struct pwm_fan_ctx * ctx)228 static int pwm_fan_of_get_cooling_data(struct device *dev,
229 struct pwm_fan_ctx *ctx)
230 {
231 struct device_node *np = dev->of_node;
232 int num, i, ret;
233
234 if (!of_find_property(np, "cooling-levels", NULL))
235 return 0;
236
237 ret = of_property_count_u32_elems(np, "cooling-levels");
238 if (ret <= 0) {
239 dev_err(dev, "Wrong data!\n");
240 return ret ? : -EINVAL;
241 }
242
243 num = ret;
244 ctx->pwm_fan_cooling_levels = devm_kcalloc(dev, num, sizeof(u32),
245 GFP_KERNEL);
246 if (!ctx->pwm_fan_cooling_levels)
247 return -ENOMEM;
248
249 ret = of_property_read_u32_array(np, "cooling-levels",
250 ctx->pwm_fan_cooling_levels, num);
251 if (ret) {
252 dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
253 return ret;
254 }
255
256 for (i = 0; i < num; i++) {
257 if (ctx->pwm_fan_cooling_levels[i] > MAX_PWM) {
258 dev_err(dev, "PWM fan state[%d]:%d > %d\n", i,
259 ctx->pwm_fan_cooling_levels[i], MAX_PWM);
260 return -EINVAL;
261 }
262 }
263
264 ctx->pwm_fan_max_state = num - 1;
265
266 return 0;
267 }
268
pwm_fan_regulator_disable(void * data)269 static void pwm_fan_regulator_disable(void *data)
270 {
271 regulator_disable(data);
272 }
273
pwm_fan_pwm_disable(void * __ctx)274 static void pwm_fan_pwm_disable(void *__ctx)
275 {
276 struct pwm_fan_ctx *ctx = __ctx;
277 pwm_disable(ctx->pwm);
278 del_timer_sync(&ctx->rpm_timer);
279 }
280
pwm_fan_probe(struct platform_device * pdev)281 static int pwm_fan_probe(struct platform_device *pdev)
282 {
283 struct thermal_cooling_device *cdev;
284 struct device *dev = &pdev->dev;
285 struct pwm_fan_ctx *ctx;
286 struct device *hwmon;
287 int ret;
288 struct pwm_state state = { };
289 u32 ppr = 2;
290
291 ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
292 if (!ctx)
293 return -ENOMEM;
294
295 mutex_init(&ctx->lock);
296
297 ctx->pwm = devm_of_pwm_get(dev, dev->of_node, NULL);
298 if (IS_ERR(ctx->pwm))
299 return dev_err_probe(dev, PTR_ERR(ctx->pwm), "Could not get PWM\n");
300
301 platform_set_drvdata(pdev, ctx);
302
303 ctx->irq = platform_get_irq_optional(pdev, 0);
304 if (ctx->irq == -EPROBE_DEFER)
305 return ctx->irq;
306
307 ctx->reg_en = devm_regulator_get_optional(dev, "fan");
308 if (IS_ERR(ctx->reg_en)) {
309 if (PTR_ERR(ctx->reg_en) != -ENODEV)
310 return PTR_ERR(ctx->reg_en);
311
312 ctx->reg_en = NULL;
313 } else {
314 ret = regulator_enable(ctx->reg_en);
315 if (ret) {
316 dev_err(dev, "Failed to enable fan supply: %d\n", ret);
317 return ret;
318 }
319 ret = devm_add_action_or_reset(dev, pwm_fan_regulator_disable,
320 ctx->reg_en);
321 if (ret)
322 return ret;
323 }
324
325 ctx->pwm_value = MAX_PWM;
326
327 pwm_init_state(ctx->pwm, &state);
328 /*
329 * __set_pwm assumes that MAX_PWM * (period - 1) fits into an unsigned
330 * long. Check this here to prevent the fan running at a too low
331 * frequency.
332 */
333 if (state.period > ULONG_MAX / MAX_PWM + 1) {
334 dev_err(dev, "Configured period too big\n");
335 return -EINVAL;
336 }
337
338 /* Set duty cycle to maximum allowed and enable PWM output */
339 state.duty_cycle = ctx->pwm->args.period - 1;
340 state.enabled = true;
341
342 ret = pwm_apply_state(ctx->pwm, &state);
343 if (ret) {
344 dev_err(dev, "Failed to configure PWM: %d\n", ret);
345 return ret;
346 }
347 timer_setup(&ctx->rpm_timer, sample_timer, 0);
348 ret = devm_add_action_or_reset(dev, pwm_fan_pwm_disable, ctx);
349 if (ret)
350 return ret;
351
352 of_property_read_u32(dev->of_node, "pulses-per-revolution", &ppr);
353 ctx->pulses_per_revolution = ppr;
354 if (!ctx->pulses_per_revolution) {
355 dev_err(dev, "pulses-per-revolution can't be zero.\n");
356 return -EINVAL;
357 }
358
359 if (ctx->irq > 0) {
360 ret = devm_request_irq(dev, ctx->irq, pulse_handler, 0,
361 pdev->name, ctx);
362 if (ret) {
363 dev_err(dev, "Failed to request interrupt: %d\n", ret);
364 return ret;
365 }
366 ctx->sample_start = ktime_get();
367 mod_timer(&ctx->rpm_timer, jiffies + HZ);
368 }
369
370 hwmon = devm_hwmon_device_register_with_groups(dev, "pwmfan",
371 ctx, pwm_fan_groups);
372 if (IS_ERR(hwmon)) {
373 dev_err(dev, "Failed to register hwmon device\n");
374 return PTR_ERR(hwmon);
375 }
376
377 ret = pwm_fan_of_get_cooling_data(dev, ctx);
378 if (ret)
379 return ret;
380
381 ctx->pwm_fan_state = ctx->pwm_fan_max_state;
382 if (IS_ENABLED(CONFIG_THERMAL)) {
383 cdev = devm_thermal_of_cooling_device_register(dev,
384 dev->of_node, "pwm-fan", ctx, &pwm_fan_cooling_ops);
385 if (IS_ERR(cdev)) {
386 ret = PTR_ERR(cdev);
387 dev_err(dev,
388 "Failed to register pwm-fan as cooling device: %d\n",
389 ret);
390 return ret;
391 }
392 ctx->cdev = cdev;
393 thermal_cdev_update(cdev);
394 }
395
396 return 0;
397 }
398
pwm_fan_disable(struct device * dev)399 static int pwm_fan_disable(struct device *dev)
400 {
401 struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
402 struct pwm_args args;
403 int ret;
404
405 pwm_get_args(ctx->pwm, &args);
406
407 if (ctx->pwm_value) {
408 ret = pwm_config(ctx->pwm, 0, args.period);
409 if (ret < 0)
410 return ret;
411
412 pwm_disable(ctx->pwm);
413 }
414
415 if (ctx->reg_en) {
416 ret = regulator_disable(ctx->reg_en);
417 if (ret) {
418 dev_err(dev, "Failed to disable fan supply: %d\n", ret);
419 return ret;
420 }
421 }
422
423 return 0;
424 }
425
pwm_fan_shutdown(struct platform_device * pdev)426 static void pwm_fan_shutdown(struct platform_device *pdev)
427 {
428 pwm_fan_disable(&pdev->dev);
429 }
430
431 #ifdef CONFIG_PM_SLEEP
pwm_fan_suspend(struct device * dev)432 static int pwm_fan_suspend(struct device *dev)
433 {
434 return pwm_fan_disable(dev);
435 }
436
pwm_fan_resume(struct device * dev)437 static int pwm_fan_resume(struct device *dev)
438 {
439 struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
440 struct pwm_args pargs;
441 unsigned long duty;
442 int ret;
443
444 if (ctx->reg_en) {
445 ret = regulator_enable(ctx->reg_en);
446 if (ret) {
447 dev_err(dev, "Failed to enable fan supply: %d\n", ret);
448 return ret;
449 }
450 }
451
452 if (ctx->pwm_value == 0)
453 return 0;
454
455 pwm_get_args(ctx->pwm, &pargs);
456 duty = DIV_ROUND_UP_ULL(ctx->pwm_value * (pargs.period - 1), MAX_PWM);
457 ret = pwm_config(ctx->pwm, duty, pargs.period);
458 if (ret)
459 return ret;
460 return pwm_enable(ctx->pwm);
461 }
462 #endif
463
464 static SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume);
465
466 static const struct of_device_id of_pwm_fan_match[] = {
467 { .compatible = "pwm-fan", },
468 {},
469 };
470 MODULE_DEVICE_TABLE(of, of_pwm_fan_match);
471
472 static struct platform_driver pwm_fan_driver = {
473 .probe = pwm_fan_probe,
474 .shutdown = pwm_fan_shutdown,
475 .driver = {
476 .name = "pwm-fan",
477 .pm = &pwm_fan_pm,
478 .of_match_table = of_pwm_fan_match,
479 },
480 };
481
482 module_platform_driver(pwm_fan_driver);
483
484 MODULE_AUTHOR("Kamil Debski <k.debski@samsung.com>");
485 MODULE_ALIAS("platform:pwm-fan");
486 MODULE_DESCRIPTION("PWM FAN driver");
487 MODULE_LICENSE("GPL");
488