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 | |
17 | struct pwm_export { |
18 | struct device child; |
19 | struct pwm_device *pwm; |
20 | struct mutex lock; |
21 | struct pwm_state suspend; |
22 | }; |
23 | |
24 | static struct pwm_export *child_to_pwm_export(struct device *child) |
25 | { |
26 | return container_of(child, struct pwm_export, child); |
27 | } |
28 | |
29 | static 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 | |
36 | static 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: &state); |
44 | |
45 | return sysfs_emit(buf, fmt: "%llu\n" , state.period); |
46 | } |
47 | |
48 | static 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(s: buf, base: 0, res: &val); |
59 | if (ret) |
60 | return ret; |
61 | |
62 | mutex_lock(&export->lock); |
63 | pwm_get_state(pwm, state: &state); |
64 | state.period = val; |
65 | ret = pwm_apply_state(pwm, state: &state); |
66 | mutex_unlock(lock: &export->lock); |
67 | |
68 | return ret ? : size; |
69 | } |
70 | |
71 | static 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: &state); |
79 | |
80 | return sysfs_emit(buf, fmt: "%llu\n" , state.duty_cycle); |
81 | } |
82 | |
83 | static 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(s: buf, base: 0, res: &val); |
94 | if (ret) |
95 | return ret; |
96 | |
97 | mutex_lock(&export->lock); |
98 | pwm_get_state(pwm, state: &state); |
99 | state.duty_cycle = val; |
100 | ret = pwm_apply_state(pwm, state: &state); |
101 | mutex_unlock(lock: &export->lock); |
102 | |
103 | return ret ? : size; |
104 | } |
105 | |
106 | static 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: &state); |
114 | |
115 | return sysfs_emit(buf, fmt: "%d\n" , state.enabled); |
116 | } |
117 | |
118 | static 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(s: buf, base: 0, res: &val); |
128 | if (ret) |
129 | return ret; |
130 | |
131 | mutex_lock(&export->lock); |
132 | |
133 | pwm_get_state(pwm, state: &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_state(pwm, state: &state); |
148 | |
149 | unlock: |
150 | mutex_unlock(lock: &export->lock); |
151 | return ret ? : size; |
152 | } |
153 | |
154 | static 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: &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, fmt: "%s\n" , polarity); |
175 | } |
176 | |
177 | static 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(s1: buf, s2: "normal" )) |
188 | polarity = PWM_POLARITY_NORMAL; |
189 | else if (sysfs_streq(s1: buf, s2: "inversed" )) |
190 | polarity = PWM_POLARITY_INVERSED; |
191 | else |
192 | return -EINVAL; |
193 | |
194 | mutex_lock(&export->lock); |
195 | pwm_get_state(pwm, state: &state); |
196 | state.polarity = polarity; |
197 | ret = pwm_apply_state(pwm, state: &state); |
198 | mutex_unlock(lock: &export->lock); |
199 | |
200 | return ret ? : size; |
201 | } |
202 | |
203 | static 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: &result, timeout: jiffies_to_msecs(HZ)); |
212 | if (ret) |
213 | return ret; |
214 | |
215 | return sysfs_emit(buf, fmt: "%u %u\n" , result.period, result.duty_cycle); |
216 | } |
217 | |
218 | static DEVICE_ATTR_RW(period); |
219 | static DEVICE_ATTR_RW(duty_cycle); |
220 | static DEVICE_ATTR_RW(enable); |
221 | static DEVICE_ATTR_RW(polarity); |
222 | static DEVICE_ATTR_RO(capture); |
223 | |
224 | static 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 | }; |
232 | ATTRIBUTE_GROUPS(pwm); |
233 | |
234 | static void pwm_export_release(struct device *child) |
235 | { |
236 | struct pwm_export *export = child_to_pwm_export(child); |
237 | |
238 | kfree(objp: export); |
239 | } |
240 | |
241 | static 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(nr: PWMF_EXPORTED, addr: &pwm->flags)) |
248 | return -EBUSY; |
249 | |
250 | export = kzalloc(size: sizeof(*export), GFP_KERNEL); |
251 | if (!export) { |
252 | clear_bit(nr: PWMF_EXPORTED, addr: &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(dev: &export->child, name: "pwm%u" , pwm->hwpwm); |
264 | |
265 | ret = device_register(dev: &export->child); |
266 | if (ret) { |
267 | clear_bit(nr: PWMF_EXPORTED, addr: &pwm->flags); |
268 | put_device(dev: &export->child); |
269 | export = NULL; |
270 | return ret; |
271 | } |
272 | pwm_prop[0] = kasprintf(GFP_KERNEL, fmt: "EXPORT=pwm%u" , pwm->hwpwm); |
273 | pwm_prop[1] = NULL; |
274 | kobject_uevent_env(kobj: &parent->kobj, action: KOBJ_CHANGE, envp: pwm_prop); |
275 | kfree(objp: pwm_prop[0]); |
276 | |
277 | return 0; |
278 | } |
279 | |
280 | static int pwm_unexport_match(struct device *child, void *data) |
281 | { |
282 | return child_to_pwm_device(child) == data; |
283 | } |
284 | |
285 | static 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(nr: PWMF_EXPORTED, addr: &pwm->flags)) |
291 | return -ENODEV; |
292 | |
293 | child = device_find_child(dev: parent, data: pwm, match: pwm_unexport_match); |
294 | if (!child) |
295 | return -ENODEV; |
296 | |
297 | pwm_prop[0] = kasprintf(GFP_KERNEL, fmt: "UNEXPORT=pwm%u" , pwm->hwpwm); |
298 | pwm_prop[1] = NULL; |
299 | kobject_uevent_env(kobj: &parent->kobj, action: KOBJ_CHANGE, envp: pwm_prop); |
300 | kfree(objp: pwm_prop[0]); |
301 | |
302 | /* for device_find_child() */ |
303 | put_device(dev: child); |
304 | device_unregister(dev: child); |
305 | pwm_put(pwm); |
306 | |
307 | return 0; |
308 | } |
309 | |
310 | static 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(dev: parent); |
315 | struct pwm_device *pwm; |
316 | unsigned int hwpwm; |
317 | int ret; |
318 | |
319 | ret = kstrtouint(s: buf, base: 0, res: &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, index: hwpwm, label: "sysfs" ); |
327 | if (IS_ERR(ptr: pwm)) |
328 | return PTR_ERR(ptr: pwm); |
329 | |
330 | ret = pwm_export_child(parent, pwm); |
331 | if (ret < 0) |
332 | pwm_put(pwm); |
333 | |
334 | return ret ? : len; |
335 | } |
336 | static DEVICE_ATTR_WO(export); |
337 | |
338 | static 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(dev: parent); |
343 | unsigned int hwpwm; |
344 | int ret; |
345 | |
346 | ret = kstrtouint(s: buf, base: 0, res: &hwpwm); |
347 | if (ret < 0) |
348 | return ret; |
349 | |
350 | if (hwpwm >= chip->npwm) |
351 | return -ENODEV; |
352 | |
353 | ret = pwm_unexport_child(parent, pwm: &chip->pwms[hwpwm]); |
354 | |
355 | return ret ? : len; |
356 | } |
357 | static DEVICE_ATTR_WO(unexport); |
358 | |
359 | static ssize_t npwm_show(struct device *parent, struct device_attribute *attr, |
360 | char *buf) |
361 | { |
362 | const struct pwm_chip *chip = dev_get_drvdata(dev: parent); |
363 | |
364 | return sysfs_emit(buf, fmt: "%u\n" , chip->npwm); |
365 | } |
366 | static DEVICE_ATTR_RO(npwm); |
367 | |
368 | static struct attribute *pwm_chip_attrs[] = { |
369 | &dev_attr_export.attr, |
370 | &dev_attr_unexport.attr, |
371 | &dev_attr_npwm.attr, |
372 | NULL, |
373 | }; |
374 | ATTRIBUTE_GROUPS(pwm_chip); |
375 | |
376 | /* takes export->lock on success */ |
377 | static 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(dev: parent, data: pwm, match: pwm_unexport_match); |
388 | if (!child) |
389 | return NULL; |
390 | |
391 | export = child_to_pwm_export(child); |
392 | put_device(dev: child); /* for device_find_child() */ |
393 | |
394 | mutex_lock(&export->lock); |
395 | pwm_get_state(pwm, state); |
396 | |
397 | return export; |
398 | } |
399 | |
400 | static 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_state(pwm, state); |
405 | |
406 | /* release lock taken in pwm_class_get_state */ |
407 | mutex_unlock(lock: &export->lock); |
408 | |
409 | return ret; |
410 | } |
411 | |
412 | static int pwm_class_resume_npwm(struct device *parent, unsigned int npwm) |
413 | { |
414 | struct pwm_chip *chip = dev_get_drvdata(dev: 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: &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(lock: &export->lock); |
431 | continue; |
432 | } |
433 | |
434 | state.enabled = export->suspend.enabled; |
435 | ret = pwm_class_apply_state(export, pwm, state: &state); |
436 | if (ret < 0) |
437 | break; |
438 | } |
439 | |
440 | return ret; |
441 | } |
442 | |
443 | static int pwm_class_suspend(struct device *parent) |
444 | { |
445 | struct pwm_chip *chip = dev_get_drvdata(dev: 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: &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(lock: &export->lock); |
466 | continue; |
467 | } |
468 | |
469 | state.enabled = false; |
470 | ret = pwm_class_apply_state(export, pwm, state: &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, npwm: i); |
477 | break; |
478 | } |
479 | } |
480 | |
481 | return ret; |
482 | } |
483 | |
484 | static int pwm_class_resume(struct device *parent) |
485 | { |
486 | struct pwm_chip *chip = dev_get_drvdata(dev: parent); |
487 | |
488 | return pwm_class_resume_npwm(parent, npwm: chip->npwm); |
489 | } |
490 | |
491 | static DEFINE_SIMPLE_DEV_PM_OPS(pwm_class_pm_ops, pwm_class_suspend, pwm_class_resume); |
492 | |
493 | static struct class pwm_class = { |
494 | .name = "pwm" , |
495 | .dev_groups = pwm_chip_groups, |
496 | .pm = pm_sleep_ptr(&pwm_class_pm_ops), |
497 | }; |
498 | |
499 | static int pwmchip_sysfs_match(struct device *parent, const void *data) |
500 | { |
501 | return dev_get_drvdata(dev: parent) == data; |
502 | } |
503 | |
504 | void 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(cls: &pwm_class, parent: chip->dev, MKDEV(0, 0), drvdata: chip, |
513 | fmt: "pwmchip%d" , chip->base); |
514 | if (IS_ERR(ptr: parent)) { |
515 | dev_warn(chip->dev, |
516 | "device_create failed for pwm_chip sysfs export\n" ); |
517 | } |
518 | } |
519 | |
520 | void pwmchip_sysfs_unexport(struct pwm_chip *chip) |
521 | { |
522 | struct device *parent; |
523 | unsigned int i; |
524 | |
525 | parent = class_find_device(class: &pwm_class, NULL, data: chip, |
526 | match: 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(dev: parent); |
538 | device_unregister(dev: parent); |
539 | } |
540 | |
541 | static int __init pwm_sysfs_init(void) |
542 | { |
543 | return class_register(class: &pwm_class); |
544 | } |
545 | subsys_initcall(pwm_sysfs_init); |
546 | |