1 /*
2 * A simple sysfs interface for the generic PWM framework
3 *
4 * Copyright (C) 2013 H Hartley Sweeten <hsweeten@visionengravers.com>
5 *
6 * Based on previous work by Lars Poeschel <poeschel@lemonage.de>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2, or (at your option)
11 * any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 */
18
19 #include <linux/device.h>
20 #include <linux/mutex.h>
21 #include <linux/err.h>
22 #include <linux/slab.h>
23 #include <linux/kdev_t.h>
24 #include <linux/pwm.h>
25
26 struct pwm_export {
27 struct device child;
28 struct pwm_device *pwm;
29 struct mutex lock;
30 };
31
child_to_pwm_export(struct device * child)32 static struct pwm_export *child_to_pwm_export(struct device *child)
33 {
34 return container_of(child, struct pwm_export, child);
35 }
36
child_to_pwm_device(struct device * child)37 static struct pwm_device *child_to_pwm_device(struct device *child)
38 {
39 struct pwm_export *export = child_to_pwm_export(child);
40
41 return export->pwm;
42 }
43
period_show(struct device * child,struct device_attribute * attr,char * buf)44 static ssize_t period_show(struct device *child,
45 struct device_attribute *attr,
46 char *buf)
47 {
48 const struct pwm_device *pwm = child_to_pwm_device(child);
49 struct pwm_state state;
50
51 pwm_get_state(pwm, &state);
52
53 return sprintf(buf, "%u\n", state.period);
54 }
55
period_store(struct device * child,struct device_attribute * attr,const char * buf,size_t size)56 static ssize_t period_store(struct device *child,
57 struct device_attribute *attr,
58 const char *buf, size_t size)
59 {
60 struct pwm_export *export = child_to_pwm_export(child);
61 struct pwm_device *pwm = export->pwm;
62 struct pwm_state state;
63 unsigned int val;
64 int ret;
65
66 ret = kstrtouint(buf, 0, &val);
67 if (ret)
68 return ret;
69
70 mutex_lock(&export->lock);
71 pwm_get_state(pwm, &state);
72 state.period = val;
73 ret = pwm_apply_state(pwm, &state);
74 mutex_unlock(&export->lock);
75
76 return ret ? : size;
77 }
78
duty_cycle_show(struct device * child,struct device_attribute * attr,char * buf)79 static ssize_t duty_cycle_show(struct device *child,
80 struct device_attribute *attr,
81 char *buf)
82 {
83 const struct pwm_device *pwm = child_to_pwm_device(child);
84 struct pwm_state state;
85
86 pwm_get_state(pwm, &state);
87
88 return sprintf(buf, "%u\n", state.duty_cycle);
89 }
90
duty_cycle_store(struct device * child,struct device_attribute * attr,const char * buf,size_t size)91 static ssize_t duty_cycle_store(struct device *child,
92 struct device_attribute *attr,
93 const char *buf, size_t size)
94 {
95 struct pwm_export *export = child_to_pwm_export(child);
96 struct pwm_device *pwm = export->pwm;
97 struct pwm_state state;
98 unsigned int val;
99 int ret;
100
101 ret = kstrtouint(buf, 0, &val);
102 if (ret)
103 return ret;
104
105 mutex_lock(&export->lock);
106 pwm_get_state(pwm, &state);
107 state.duty_cycle = val;
108 ret = pwm_apply_state(pwm, &state);
109 mutex_unlock(&export->lock);
110
111 return ret ? : size;
112 }
113
enable_show(struct device * child,struct device_attribute * attr,char * buf)114 static ssize_t enable_show(struct device *child,
115 struct device_attribute *attr,
116 char *buf)
117 {
118 const struct pwm_device *pwm = child_to_pwm_device(child);
119 struct pwm_state state;
120
121 pwm_get_state(pwm, &state);
122
123 return sprintf(buf, "%d\n", state.enabled);
124 }
125
enable_store(struct device * child,struct device_attribute * attr,const char * buf,size_t size)126 static ssize_t enable_store(struct device *child,
127 struct device_attribute *attr,
128 const char *buf, size_t size)
129 {
130 struct pwm_export *export = child_to_pwm_export(child);
131 struct pwm_device *pwm = export->pwm;
132 struct pwm_state state;
133 int val, ret;
134
135 ret = kstrtoint(buf, 0, &val);
136 if (ret)
137 return ret;
138
139 mutex_lock(&export->lock);
140
141 pwm_get_state(pwm, &state);
142
143 switch (val) {
144 case 0:
145 state.enabled = false;
146 break;
147 case 1:
148 state.enabled = true;
149 break;
150 default:
151 ret = -EINVAL;
152 goto unlock;
153 }
154
155 ret = pwm_apply_state(pwm, &state);
156
157 unlock:
158 mutex_unlock(&export->lock);
159 return ret ? : size;
160 }
161
polarity_show(struct device * child,struct device_attribute * attr,char * buf)162 static ssize_t polarity_show(struct device *child,
163 struct device_attribute *attr,
164 char *buf)
165 {
166 const struct pwm_device *pwm = child_to_pwm_device(child);
167 const char *polarity = "unknown";
168 struct pwm_state state;
169
170 pwm_get_state(pwm, &state);
171
172 switch (state.polarity) {
173 case PWM_POLARITY_NORMAL:
174 polarity = "normal";
175 break;
176
177 case PWM_POLARITY_INVERSED:
178 polarity = "inversed";
179 break;
180 }
181
182 return sprintf(buf, "%s\n", polarity);
183 }
184
polarity_store(struct device * child,struct device_attribute * attr,const char * buf,size_t size)185 static ssize_t polarity_store(struct device *child,
186 struct device_attribute *attr,
187 const char *buf, size_t size)
188 {
189 struct pwm_export *export = child_to_pwm_export(child);
190 struct pwm_device *pwm = export->pwm;
191 enum pwm_polarity polarity;
192 struct pwm_state state;
193 int ret;
194
195 if (sysfs_streq(buf, "normal"))
196 polarity = PWM_POLARITY_NORMAL;
197 else if (sysfs_streq(buf, "inversed"))
198 polarity = PWM_POLARITY_INVERSED;
199 else
200 return -EINVAL;
201
202 mutex_lock(&export->lock);
203 pwm_get_state(pwm, &state);
204 state.polarity = polarity;
205 ret = pwm_apply_state(pwm, &state);
206 mutex_unlock(&export->lock);
207
208 return ret ? : size;
209 }
210
capture_show(struct device * child,struct device_attribute * attr,char * buf)211 static ssize_t capture_show(struct device *child,
212 struct device_attribute *attr,
213 char *buf)
214 {
215 struct pwm_device *pwm = child_to_pwm_device(child);
216 struct pwm_capture result;
217 int ret;
218
219 ret = pwm_capture(pwm, &result, jiffies_to_msecs(HZ));
220 if (ret)
221 return ret;
222
223 return sprintf(buf, "%u %u\n", result.period, result.duty_cycle);
224 }
225
226 static DEVICE_ATTR_RW(period);
227 static DEVICE_ATTR_RW(duty_cycle);
228 static DEVICE_ATTR_RW(enable);
229 static DEVICE_ATTR_RW(polarity);
230 static DEVICE_ATTR_RO(capture);
231
232 static struct attribute *pwm_attrs[] = {
233 &dev_attr_period.attr,
234 &dev_attr_duty_cycle.attr,
235 &dev_attr_enable.attr,
236 &dev_attr_polarity.attr,
237 &dev_attr_capture.attr,
238 NULL
239 };
240 ATTRIBUTE_GROUPS(pwm);
241
pwm_export_release(struct device * child)242 static void pwm_export_release(struct device *child)
243 {
244 struct pwm_export *export = child_to_pwm_export(child);
245
246 kfree(export);
247 }
248
pwm_export_child(struct device * parent,struct pwm_device * pwm)249 static int pwm_export_child(struct device *parent, struct pwm_device *pwm)
250 {
251 struct pwm_export *export;
252 int ret;
253
254 if (test_and_set_bit(PWMF_EXPORTED, &pwm->flags))
255 return -EBUSY;
256
257 export = kzalloc(sizeof(*export), GFP_KERNEL);
258 if (!export) {
259 clear_bit(PWMF_EXPORTED, &pwm->flags);
260 return -ENOMEM;
261 }
262
263 export->pwm = pwm;
264 mutex_init(&export->lock);
265
266 export->child.class = parent->class;
267 export->child.release = pwm_export_release;
268 export->child.parent = parent;
269 export->child.devt = MKDEV(0, 0);
270 export->child.groups = pwm_groups;
271 dev_set_name(&export->child, "pwm%u", pwm->hwpwm);
272
273 ret = device_register(&export->child);
274 if (ret) {
275 clear_bit(PWMF_EXPORTED, &pwm->flags);
276 put_device(&export->child);
277 export = NULL;
278 return ret;
279 }
280
281 return 0;
282 }
283
pwm_unexport_match(struct device * child,void * data)284 static int pwm_unexport_match(struct device *child, void *data)
285 {
286 return child_to_pwm_device(child) == data;
287 }
288
pwm_unexport_child(struct device * parent,struct pwm_device * pwm)289 static int pwm_unexport_child(struct device *parent, struct pwm_device *pwm)
290 {
291 struct device *child;
292
293 if (!test_and_clear_bit(PWMF_EXPORTED, &pwm->flags))
294 return -ENODEV;
295
296 child = device_find_child(parent, pwm, pwm_unexport_match);
297 if (!child)
298 return -ENODEV;
299
300 /* for device_find_child() */
301 put_device(child);
302 device_unregister(child);
303 pwm_put(pwm);
304
305 return 0;
306 }
307
export_store(struct device * parent,struct device_attribute * attr,const char * buf,size_t len)308 static ssize_t export_store(struct device *parent,
309 struct device_attribute *attr,
310 const char *buf, size_t len)
311 {
312 struct pwm_chip *chip = dev_get_drvdata(parent);
313 struct pwm_device *pwm;
314 unsigned int hwpwm;
315 int ret;
316
317 ret = kstrtouint(buf, 0, &hwpwm);
318 if (ret < 0)
319 return ret;
320
321 if (hwpwm >= chip->npwm)
322 return -ENODEV;
323
324 pwm = pwm_request_from_chip(chip, hwpwm, "sysfs");
325 if (IS_ERR(pwm))
326 return PTR_ERR(pwm);
327
328 ret = pwm_export_child(parent, pwm);
329 if (ret < 0)
330 pwm_put(pwm);
331
332 return ret ? : len;
333 }
334 static DEVICE_ATTR_WO(export);
335
unexport_store(struct device * parent,struct device_attribute * attr,const char * buf,size_t len)336 static ssize_t unexport_store(struct device *parent,
337 struct device_attribute *attr,
338 const char *buf, size_t len)
339 {
340 struct pwm_chip *chip = dev_get_drvdata(parent);
341 unsigned int hwpwm;
342 int ret;
343
344 ret = kstrtouint(buf, 0, &hwpwm);
345 if (ret < 0)
346 return ret;
347
348 if (hwpwm >= chip->npwm)
349 return -ENODEV;
350
351 ret = pwm_unexport_child(parent, &chip->pwms[hwpwm]);
352
353 return ret ? : len;
354 }
355 static DEVICE_ATTR_WO(unexport);
356
npwm_show(struct device * parent,struct device_attribute * attr,char * buf)357 static ssize_t npwm_show(struct device *parent, struct device_attribute *attr,
358 char *buf)
359 {
360 const struct pwm_chip *chip = dev_get_drvdata(parent);
361
362 return sprintf(buf, "%u\n", chip->npwm);
363 }
364 static DEVICE_ATTR_RO(npwm);
365
366 static struct attribute *pwm_chip_attrs[] = {
367 &dev_attr_export.attr,
368 &dev_attr_unexport.attr,
369 &dev_attr_npwm.attr,
370 NULL,
371 };
372 ATTRIBUTE_GROUPS(pwm_chip);
373
374 static struct class pwm_class = {
375 .name = "pwm",
376 .owner = THIS_MODULE,
377 .dev_groups = pwm_chip_groups,
378 };
379
pwmchip_sysfs_match(struct device * parent,const void * data)380 static int pwmchip_sysfs_match(struct device *parent, const void *data)
381 {
382 return dev_get_drvdata(parent) == data;
383 }
384
pwmchip_sysfs_export(struct pwm_chip * chip)385 void pwmchip_sysfs_export(struct pwm_chip *chip)
386 {
387 struct device *parent;
388
389 /*
390 * If device_create() fails the pwm_chip is still usable by
391 * the kernel its just not exported.
392 */
393 parent = device_create(&pwm_class, chip->dev, MKDEV(0, 0), chip,
394 "pwmchip%d", chip->base);
395 if (IS_ERR(parent)) {
396 dev_warn(chip->dev,
397 "device_create failed for pwm_chip sysfs export\n");
398 }
399 }
400
pwmchip_sysfs_unexport(struct pwm_chip * chip)401 void pwmchip_sysfs_unexport(struct pwm_chip *chip)
402 {
403 struct device *parent;
404
405 parent = class_find_device(&pwm_class, NULL, chip,
406 pwmchip_sysfs_match);
407 if (parent) {
408 /* for class_find_device() */
409 put_device(parent);
410 device_unregister(parent);
411 }
412 }
413
pwmchip_sysfs_unexport_children(struct pwm_chip * chip)414 void pwmchip_sysfs_unexport_children(struct pwm_chip *chip)
415 {
416 struct device *parent;
417 unsigned int i;
418
419 parent = class_find_device(&pwm_class, NULL, chip,
420 pwmchip_sysfs_match);
421 if (!parent)
422 return;
423
424 for (i = 0; i < chip->npwm; i++) {
425 struct pwm_device *pwm = &chip->pwms[i];
426
427 if (test_bit(PWMF_EXPORTED, &pwm->flags))
428 pwm_unexport_child(parent, pwm);
429 }
430
431 put_device(parent);
432 }
433
pwm_sysfs_init(void)434 static int __init pwm_sysfs_init(void)
435 {
436 return class_register(&pwm_class);
437 }
438 subsys_initcall(pwm_sysfs_init);
439
