1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * A simple sysfs interface for the generic PWM framework
4 *
5 * Copyright (C) 2013 H Hartley Sweeten <hsweeten@visionengravers.com>
6 *
7 * Based on previous work by Lars Poeschel <poeschel@lemonage.de>
8 */
9
10#include <linux/device.h>
11#include <linux/mutex.h>
12#include <linux/err.h>
13#include <linux/slab.h>
14#include <linux/kdev_t.h>
15#include <linux/pwm.h>
16
17struct pwm_export {
18	struct device child;
19	struct pwm_device *pwm;
20	struct mutex lock;
21	struct pwm_state suspend;
22};
23
24static struct pwm_export *child_to_pwm_export(struct device *child)
25{
26	return container_of(child, struct pwm_export, child);
27}
28
29static struct pwm_device *child_to_pwm_device(struct device *child)
30{
31	struct pwm_export *export = child_to_pwm_export(child);
32
33	return export->pwm;
34}
35
36static ssize_t period_show(struct device *child,
37			   struct device_attribute *attr,
38			   char *buf)
39{
40	const struct pwm_device *pwm = child_to_pwm_device(child);
41	struct pwm_state state;
42
43	pwm_get_state(pwm, &state);
44
45	return sysfs_emit(buf, "%llu\n", state.period);
46}
47
48static ssize_t period_store(struct device *child,
49			    struct device_attribute *attr,
50			    const char *buf, size_t size)
51{
52	struct pwm_export *export = child_to_pwm_export(child);
53	struct pwm_device *pwm = export->pwm;
54	struct pwm_state state;
55	u64 val;
56	int ret;
57
58	ret = kstrtou64(buf, 0, &val);
59	if (ret)
60		return ret;
61
62	mutex_lock(&export->lock);
63	pwm_get_state(pwm, &state);
64	state.period = val;
65	ret = pwm_apply_might_sleep(pwm, &state);
66	mutex_unlock(&export->lock);
67
68	return ret ? : size;
69}
70
71static ssize_t duty_cycle_show(struct device *child,
72			       struct device_attribute *attr,
73			       char *buf)
74{
75	const struct pwm_device *pwm = child_to_pwm_device(child);
76	struct pwm_state state;
77
78	pwm_get_state(pwm, &state);
79
80	return sysfs_emit(buf, "%llu\n", state.duty_cycle);
81}
82
83static ssize_t duty_cycle_store(struct device *child,
84				struct device_attribute *attr,
85				const char *buf, size_t size)
86{
87	struct pwm_export *export = child_to_pwm_export(child);
88	struct pwm_device *pwm = export->pwm;
89	struct pwm_state state;
90	u64 val;
91	int ret;
92
93	ret = kstrtou64(buf, 0, &val);
94	if (ret)
95		return ret;
96
97	mutex_lock(&export->lock);
98	pwm_get_state(pwm, &state);
99	state.duty_cycle = val;
100	ret = pwm_apply_might_sleep(pwm, &state);
101	mutex_unlock(&export->lock);
102
103	return ret ? : size;
104}
105
106static ssize_t enable_show(struct device *child,
107			   struct device_attribute *attr,
108			   char *buf)
109{
110	const struct pwm_device *pwm = child_to_pwm_device(child);
111	struct pwm_state state;
112
113	pwm_get_state(pwm, &state);
114
115	return sysfs_emit(buf, "%d\n", state.enabled);
116}
117
118static ssize_t enable_store(struct device *child,
119			    struct device_attribute *attr,
120			    const char *buf, size_t size)
121{
122	struct pwm_export *export = child_to_pwm_export(child);
123	struct pwm_device *pwm = export->pwm;
124	struct pwm_state state;
125	int val, ret;
126
127	ret = kstrtoint(buf, 0, &val);
128	if (ret)
129		return ret;
130
131	mutex_lock(&export->lock);
132
133	pwm_get_state(pwm, &state);
134
135	switch (val) {
136	case 0:
137		state.enabled = false;
138		break;
139	case 1:
140		state.enabled = true;
141		break;
142	default:
143		ret = -EINVAL;
144		goto unlock;
145	}
146
147	ret = pwm_apply_might_sleep(pwm, &state);
148
149unlock:
150	mutex_unlock(&export->lock);
151	return ret ? : size;
152}
153
154static ssize_t polarity_show(struct device *child,
155			     struct device_attribute *attr,
156			     char *buf)
157{
158	const struct pwm_device *pwm = child_to_pwm_device(child);
159	const char *polarity = "unknown";
160	struct pwm_state state;
161
162	pwm_get_state(pwm, &state);
163
164	switch (state.polarity) {
165	case PWM_POLARITY_NORMAL:
166		polarity = "normal";
167		break;
168
169	case PWM_POLARITY_INVERSED:
170		polarity = "inversed";
171		break;
172	}
173
174	return sysfs_emit(buf, "%s\n", polarity);
175}
176
177static ssize_t polarity_store(struct device *child,
178			      struct device_attribute *attr,
179			      const char *buf, size_t size)
180{
181	struct pwm_export *export = child_to_pwm_export(child);
182	struct pwm_device *pwm = export->pwm;
183	enum pwm_polarity polarity;
184	struct pwm_state state;
185	int ret;
186
187	if (sysfs_streq(buf, "normal"))
188		polarity = PWM_POLARITY_NORMAL;
189	else if (sysfs_streq(buf, "inversed"))
190		polarity = PWM_POLARITY_INVERSED;
191	else
192		return -EINVAL;
193
194	mutex_lock(&export->lock);
195	pwm_get_state(pwm, &state);
196	state.polarity = polarity;
197	ret = pwm_apply_might_sleep(pwm, &state);
198	mutex_unlock(&export->lock);
199
200	return ret ? : size;
201}
202
203static ssize_t capture_show(struct device *child,
204			    struct device_attribute *attr,
205			    char *buf)
206{
207	struct pwm_device *pwm = child_to_pwm_device(child);
208	struct pwm_capture result;
209	int ret;
210
211	ret = pwm_capture(pwm, &result, jiffies_to_msecs(HZ));
212	if (ret)
213		return ret;
214
215	return sysfs_emit(buf, "%u %u\n", result.period, result.duty_cycle);
216}
217
218static DEVICE_ATTR_RW(period);
219static DEVICE_ATTR_RW(duty_cycle);
220static DEVICE_ATTR_RW(enable);
221static DEVICE_ATTR_RW(polarity);
222static DEVICE_ATTR_RO(capture);
223
224static struct attribute *pwm_attrs[] = {
225	&dev_attr_period.attr,
226	&dev_attr_duty_cycle.attr,
227	&dev_attr_enable.attr,
228	&dev_attr_polarity.attr,
229	&dev_attr_capture.attr,
230	NULL
231};
232ATTRIBUTE_GROUPS(pwm);
233
234static void pwm_export_release(struct device *child)
235{
236	struct pwm_export *export = child_to_pwm_export(child);
237
238	kfree(export);
239}
240
241static int pwm_export_child(struct device *parent, struct pwm_device *pwm)
242{
243	struct pwm_export *export;
244	char *pwm_prop[2];
245	int ret;
246
247	if (test_and_set_bit(PWMF_EXPORTED, &pwm->flags))
248		return -EBUSY;
249
250	export = kzalloc(sizeof(*export), GFP_KERNEL);
251	if (!export) {
252		clear_bit(PWMF_EXPORTED, &pwm->flags);
253		return -ENOMEM;
254	}
255
256	export->pwm = pwm;
257	mutex_init(&export->lock);
258
259	export->child.release = pwm_export_release;
260	export->child.parent = parent;
261	export->child.devt = MKDEV(0, 0);
262	export->child.groups = pwm_groups;
263	dev_set_name(&export->child, "pwm%u", pwm->hwpwm);
264
265	ret = device_register(&export->child);
266	if (ret) {
267		clear_bit(PWMF_EXPORTED, &pwm->flags);
268		put_device(&export->child);
269		export = NULL;
270		return ret;
271	}
272	pwm_prop[0] = kasprintf(GFP_KERNEL, "EXPORT=pwm%u", pwm->hwpwm);
273	pwm_prop[1] = NULL;
274	kobject_uevent_env(&parent->kobj, KOBJ_CHANGE, pwm_prop);
275	kfree(pwm_prop[0]);
276
277	return 0;
278}
279
280static int pwm_unexport_match(struct device *child, void *data)
281{
282	return child_to_pwm_device(child) == data;
283}
284
285static int pwm_unexport_child(struct device *parent, struct pwm_device *pwm)
286{
287	struct device *child;
288	char *pwm_prop[2];
289
290	if (!test_and_clear_bit(PWMF_EXPORTED, &pwm->flags))
291		return -ENODEV;
292
293	child = device_find_child(parent, pwm, pwm_unexport_match);
294	if (!child)
295		return -ENODEV;
296
297	pwm_prop[0] = kasprintf(GFP_KERNEL, "UNEXPORT=pwm%u", pwm->hwpwm);
298	pwm_prop[1] = NULL;
299	kobject_uevent_env(&parent->kobj, KOBJ_CHANGE, pwm_prop);
300	kfree(pwm_prop[0]);
301
302	/* for device_find_child() */
303	put_device(child);
304	device_unregister(child);
305	pwm_put(pwm);
306
307	return 0;
308}
309
310static ssize_t export_store(struct device *parent,
311			    struct device_attribute *attr,
312			    const char *buf, size_t len)
313{
314	struct pwm_chip *chip = dev_get_drvdata(parent);
315	struct pwm_device *pwm;
316	unsigned int hwpwm;
317	int ret;
318
319	ret = kstrtouint(buf, 0, &hwpwm);
320	if (ret < 0)
321		return ret;
322
323	if (hwpwm >= chip->npwm)
324		return -ENODEV;
325
326	pwm = pwm_request_from_chip(chip, hwpwm, "sysfs");
327	if (IS_ERR(pwm))
328		return PTR_ERR(pwm);
329
330	ret = pwm_export_child(parent, pwm);
331	if (ret < 0)
332		pwm_put(pwm);
333
334	return ret ? : len;
335}
336static DEVICE_ATTR_WO(export);
337
338static ssize_t unexport_store(struct device *parent,
339			      struct device_attribute *attr,
340			      const char *buf, size_t len)
341{
342	struct pwm_chip *chip = dev_get_drvdata(parent);
343	unsigned int hwpwm;
344	int ret;
345
346	ret = kstrtouint(buf, 0, &hwpwm);
347	if (ret < 0)
348		return ret;
349
350	if (hwpwm >= chip->npwm)
351		return -ENODEV;
352
353	ret = pwm_unexport_child(parent, &chip->pwms[hwpwm]);
354
355	return ret ? : len;
356}
357static DEVICE_ATTR_WO(unexport);
358
359static ssize_t npwm_show(struct device *parent, struct device_attribute *attr,
360			 char *buf)
361{
362	const struct pwm_chip *chip = dev_get_drvdata(parent);
363
364	return sysfs_emit(buf, "%u\n", chip->npwm);
365}
366static DEVICE_ATTR_RO(npwm);
367
368static struct attribute *pwm_chip_attrs[] = {
369	&dev_attr_export.attr,
370	&dev_attr_unexport.attr,
371	&dev_attr_npwm.attr,
372	NULL,
373};
374ATTRIBUTE_GROUPS(pwm_chip);
375
376/* takes export->lock on success */
377static struct pwm_export *pwm_class_get_state(struct device *parent,
378					      struct pwm_device *pwm,
379					      struct pwm_state *state)
380{
381	struct device *child;
382	struct pwm_export *export;
383
384	if (!test_bit(PWMF_EXPORTED, &pwm->flags))
385		return NULL;
386
387	child = device_find_child(parent, pwm, pwm_unexport_match);
388	if (!child)
389		return NULL;
390
391	export = child_to_pwm_export(child);
392	put_device(child);	/* for device_find_child() */
393
394	mutex_lock(&export->lock);
395	pwm_get_state(pwm, state);
396
397	return export;
398}
399
400static int pwm_class_apply_state(struct pwm_export *export,
401				 struct pwm_device *pwm,
402				 struct pwm_state *state)
403{
404	int ret = pwm_apply_might_sleep(pwm, state);
405
406	/* release lock taken in pwm_class_get_state */
407	mutex_unlock(&export->lock);
408
409	return ret;
410}
411
412static int pwm_class_resume_npwm(struct device *parent, unsigned int npwm)
413{
414	struct pwm_chip *chip = dev_get_drvdata(parent);
415	unsigned int i;
416	int ret = 0;
417
418	for (i = 0; i < npwm; i++) {
419		struct pwm_device *pwm = &chip->pwms[i];
420		struct pwm_state state;
421		struct pwm_export *export;
422
423		export = pwm_class_get_state(parent, pwm, &state);
424		if (!export)
425			continue;
426
427		/* If pwmchip was not enabled before suspend, do nothing. */
428		if (!export->suspend.enabled) {
429			/* release lock taken in pwm_class_get_state */
430			mutex_unlock(&export->lock);
431			continue;
432		}
433
434		state.enabled = export->suspend.enabled;
435		ret = pwm_class_apply_state(export, pwm, &state);
436		if (ret < 0)
437			break;
438	}
439
440	return ret;
441}
442
443static int pwm_class_suspend(struct device *parent)
444{
445	struct pwm_chip *chip = dev_get_drvdata(parent);
446	unsigned int i;
447	int ret = 0;
448
449	for (i = 0; i < chip->npwm; i++) {
450		struct pwm_device *pwm = &chip->pwms[i];
451		struct pwm_state state;
452		struct pwm_export *export;
453
454		export = pwm_class_get_state(parent, pwm, &state);
455		if (!export)
456			continue;
457
458		/*
459		 * If pwmchip was not enabled before suspend, save
460		 * state for resume time and do nothing else.
461		 */
462		export->suspend = state;
463		if (!state.enabled) {
464			/* release lock taken in pwm_class_get_state */
465			mutex_unlock(&export->lock);
466			continue;
467		}
468
469		state.enabled = false;
470		ret = pwm_class_apply_state(export, pwm, &state);
471		if (ret < 0) {
472			/*
473			 * roll back the PWM devices that were disabled by
474			 * this suspend function.
475			 */
476			pwm_class_resume_npwm(parent, i);
477			break;
478		}
479	}
480
481	return ret;
482}
483
484static int pwm_class_resume(struct device *parent)
485{
486	struct pwm_chip *chip = dev_get_drvdata(parent);
487
488	return pwm_class_resume_npwm(parent, chip->npwm);
489}
490
491static DEFINE_SIMPLE_DEV_PM_OPS(pwm_class_pm_ops, pwm_class_suspend, pwm_class_resume);
492
493static struct class pwm_class = {
494	.name = "pwm",
495	.dev_groups = pwm_chip_groups,
496	.pm = pm_sleep_ptr(&pwm_class_pm_ops),
497};
498
499static int pwmchip_sysfs_match(struct device *parent, const void *data)
500{
501	return dev_get_drvdata(parent) == data;
502}
503
504void pwmchip_sysfs_export(struct pwm_chip *chip)
505{
506	struct device *parent;
507
508	/*
509	 * If device_create() fails the pwm_chip is still usable by
510	 * the kernel it's just not exported.
511	 */
512	parent = device_create(&pwm_class, pwmchip_parent(chip), MKDEV(0, 0), chip,
513			       "pwmchip%d", chip->id);
514	if (IS_ERR(parent)) {
515		dev_warn(pwmchip_parent(chip),
516			 "device_create failed for pwm_chip sysfs export\n");
517	}
518}
519
520void pwmchip_sysfs_unexport(struct pwm_chip *chip)
521{
522	struct device *parent;
523	unsigned int i;
524
525	parent = class_find_device(&pwm_class, NULL, chip,
526				   pwmchip_sysfs_match);
527	if (!parent)
528		return;
529
530	for (i = 0; i < chip->npwm; i++) {
531		struct pwm_device *pwm = &chip->pwms[i];
532
533		if (test_bit(PWMF_EXPORTED, &pwm->flags))
534			pwm_unexport_child(parent, pwm);
535	}
536
537	put_device(parent);
538	device_unregister(parent);
539}
540
541static int __init pwm_sysfs_init(void)
542{
543	return class_register(&pwm_class);
544}
545subsys_initcall(pwm_sysfs_init);
546