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.release = pwm_export_release;
267 	export->child.parent = parent;
268 	export->child.devt = MKDEV(0, 0);
269 	export->child.groups = pwm_groups;
270 	dev_set_name(&export->child, "pwm%u", pwm->hwpwm);
271 
272 	ret = device_register(&export->child);
273 	if (ret) {
274 		clear_bit(PWMF_EXPORTED, &pwm->flags);
275 		put_device(&export->child);
276 		export = NULL;
277 		return ret;
278 	}
279 
280 	return 0;
281 }
282 
pwm_unexport_match(struct device * child,void * data)283 static int pwm_unexport_match(struct device *child, void *data)
284 {
285 	return child_to_pwm_device(child) == data;
286 }
287 
pwm_unexport_child(struct device * parent,struct pwm_device * pwm)288 static int pwm_unexport_child(struct device *parent, struct pwm_device *pwm)
289 {
290 	struct device *child;
291 
292 	if (!test_and_clear_bit(PWMF_EXPORTED, &pwm->flags))
293 		return -ENODEV;
294 
295 	child = device_find_child(parent, pwm, pwm_unexport_match);
296 	if (!child)
297 		return -ENODEV;
298 
299 	/* for device_find_child() */
300 	put_device(child);
301 	device_unregister(child);
302 	pwm_put(pwm);
303 
304 	return 0;
305 }
306 
export_store(struct device * parent,struct device_attribute * attr,const char * buf,size_t len)307 static ssize_t export_store(struct device *parent,
308 			    struct device_attribute *attr,
309 			    const char *buf, size_t len)
310 {
311 	struct pwm_chip *chip = dev_get_drvdata(parent);
312 	struct pwm_device *pwm;
313 	unsigned int hwpwm;
314 	int ret;
315 
316 	ret = kstrtouint(buf, 0, &hwpwm);
317 	if (ret < 0)
318 		return ret;
319 
320 	if (hwpwm >= chip->npwm)
321 		return -ENODEV;
322 
323 	pwm = pwm_request_from_chip(chip, hwpwm, "sysfs");
324 	if (IS_ERR(pwm))
325 		return PTR_ERR(pwm);
326 
327 	ret = pwm_export_child(parent, pwm);
328 	if (ret < 0)
329 		pwm_put(pwm);
330 
331 	return ret ? : len;
332 }
333 static DEVICE_ATTR_WO(export);
334 
unexport_store(struct device * parent,struct device_attribute * attr,const char * buf,size_t len)335 static ssize_t unexport_store(struct device *parent,
336 			      struct device_attribute *attr,
337 			      const char *buf, size_t len)
338 {
339 	struct pwm_chip *chip = dev_get_drvdata(parent);
340 	unsigned int hwpwm;
341 	int ret;
342 
343 	ret = kstrtouint(buf, 0, &hwpwm);
344 	if (ret < 0)
345 		return ret;
346 
347 	if (hwpwm >= chip->npwm)
348 		return -ENODEV;
349 
350 	ret = pwm_unexport_child(parent, &chip->pwms[hwpwm]);
351 
352 	return ret ? : len;
353 }
354 static DEVICE_ATTR_WO(unexport);
355 
npwm_show(struct device * parent,struct device_attribute * attr,char * buf)356 static ssize_t npwm_show(struct device *parent, struct device_attribute *attr,
357 			 char *buf)
358 {
359 	const struct pwm_chip *chip = dev_get_drvdata(parent);
360 
361 	return sprintf(buf, "%u\n", chip->npwm);
362 }
363 static DEVICE_ATTR_RO(npwm);
364 
365 static struct attribute *pwm_chip_attrs[] = {
366 	&dev_attr_export.attr,
367 	&dev_attr_unexport.attr,
368 	&dev_attr_npwm.attr,
369 	NULL,
370 };
371 ATTRIBUTE_GROUPS(pwm_chip);
372 
373 static struct class pwm_class = {
374 	.name = "pwm",
375 	.owner = THIS_MODULE,
376 	.dev_groups = pwm_chip_groups,
377 };
378 
pwmchip_sysfs_match(struct device * parent,const void * data)379 static int pwmchip_sysfs_match(struct device *parent, const void *data)
380 {
381 	return dev_get_drvdata(parent) == data;
382 }
383 
pwmchip_sysfs_export(struct pwm_chip * chip)384 void pwmchip_sysfs_export(struct pwm_chip *chip)
385 {
386 	struct device *parent;
387 
388 	/*
389 	 * If device_create() fails the pwm_chip is still usable by
390 	 * the kernel its just not exported.
391 	 */
392 	parent = device_create(&pwm_class, chip->dev, MKDEV(0, 0), chip,
393 			       "pwmchip%d", chip->base);
394 	if (IS_ERR(parent)) {
395 		dev_warn(chip->dev,
396 			 "device_create failed for pwm_chip sysfs export\n");
397 	}
398 }
399 
pwmchip_sysfs_unexport(struct pwm_chip * chip)400 void pwmchip_sysfs_unexport(struct pwm_chip *chip)
401 {
402 	struct device *parent;
403 	unsigned int i;
404 
405 	parent = class_find_device(&pwm_class, NULL, chip,
406 				   pwmchip_sysfs_match);
407 	if (!parent)
408 		return;
409 
410 	for (i = 0; i < chip->npwm; i++) {
411 		struct pwm_device *pwm = &chip->pwms[i];
412 
413 		if (test_bit(PWMF_EXPORTED, &pwm->flags))
414 			pwm_unexport_child(parent, pwm);
415 	}
416 
417 	put_device(parent);
418 	device_unregister(parent);
419 }
420 
pwm_sysfs_init(void)421 static int __init pwm_sysfs_init(void)
422 {
423 	return class_register(&pwm_class);
424 }
425 subsys_initcall(pwm_sysfs_init);
426