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H Hartley Sweeten76abbdde2013-06-11 10:38:59 -07001/*
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
26struct pwm_export {
27 struct device child;
28 struct pwm_device *pwm;
29};
30
31static struct pwm_export *child_to_pwm_export(struct device *child)
32{
33 return container_of(child, struct pwm_export, child);
34}
35
36static struct pwm_device *child_to_pwm_device(struct device *child)
37{
38 struct pwm_export *export = child_to_pwm_export(child);
39
40 return export->pwm;
41}
42
43static ssize_t pwm_period_show(struct device *child,
44 struct device_attribute *attr,
45 char *buf)
46{
47 const struct pwm_device *pwm = child_to_pwm_device(child);
48
49 return sprintf(buf, "%u\n", pwm->period);
50}
51
52static ssize_t pwm_period_store(struct device *child,
53 struct device_attribute *attr,
54 const char *buf, size_t size)
55{
56 struct pwm_device *pwm = child_to_pwm_device(child);
57 unsigned int val;
58 int ret;
59
60 ret = kstrtouint(buf, 0, &val);
61 if (ret)
62 return ret;
63
64 ret = pwm_config(pwm, pwm->duty_cycle, val);
65
66 return ret ? : size;
67}
68
69static ssize_t pwm_duty_cycle_show(struct device *child,
70 struct device_attribute *attr,
71 char *buf)
72{
73 const struct pwm_device *pwm = child_to_pwm_device(child);
74
75 return sprintf(buf, "%u\n", pwm->duty_cycle);
76}
77
78static ssize_t pwm_duty_cycle_store(struct device *child,
79 struct device_attribute *attr,
80 const char *buf, size_t size)
81{
82 struct pwm_device *pwm = child_to_pwm_device(child);
83 unsigned int val;
84 int ret;
85
86 ret = kstrtouint(buf, 0, &val);
87 if (ret)
88 return ret;
89
90 ret = pwm_config(pwm, val, pwm->period);
91
92 return ret ? : size;
93}
94
95static ssize_t pwm_enable_show(struct device *child,
96 struct device_attribute *attr,
97 char *buf)
98{
99 const struct pwm_device *pwm = child_to_pwm_device(child);
100 int enabled = test_bit(PWMF_ENABLED, &pwm->flags);
101
102 return sprintf(buf, "%d\n", enabled);
103}
104
105static ssize_t pwm_enable_store(struct device *child,
106 struct device_attribute *attr,
107 const char *buf, size_t size)
108{
109 struct pwm_device *pwm = child_to_pwm_device(child);
110 int val, ret;
111
112 ret = kstrtoint(buf, 0, &val);
113 if (ret)
114 return ret;
115
116 switch (val) {
117 case 0:
118 pwm_disable(pwm);
119 break;
120 case 1:
121 ret = pwm_enable(pwm);
122 break;
123 default:
124 ret = -EINVAL;
125 break;
126 }
127
128 return ret ? : size;
129}
130
131static ssize_t pwm_polarity_show(struct device *child,
132 struct device_attribute *attr,
133 char *buf)
134{
135 const struct pwm_device *pwm = child_to_pwm_device(child);
136
137 return sprintf(buf, "%s\n", pwm->polarity ? "inversed" : "normal");
138}
139
140static ssize_t pwm_polarity_store(struct device *child,
141 struct device_attribute *attr,
142 const char *buf, size_t size)
143{
144 struct pwm_device *pwm = child_to_pwm_device(child);
145 enum pwm_polarity polarity;
146 int ret;
147
148 if (sysfs_streq(buf, "normal"))
149 polarity = PWM_POLARITY_NORMAL;
150 else if (sysfs_streq(buf, "inversed"))
151 polarity = PWM_POLARITY_INVERSED;
152 else
153 return -EINVAL;
154
155 ret = pwm_set_polarity(pwm, polarity);
156
157 return ret ? : size;
158}
159
160static DEVICE_ATTR(period, 0644, pwm_period_show, pwm_period_store);
161static DEVICE_ATTR(duty_cycle, 0644, pwm_duty_cycle_show, pwm_duty_cycle_store);
162static DEVICE_ATTR(enable, 0644, pwm_enable_show, pwm_enable_store);
163static DEVICE_ATTR(polarity, 0644, pwm_polarity_show, pwm_polarity_store);
164
165static struct attribute *pwm_attrs[] = {
166 &dev_attr_period.attr,
167 &dev_attr_duty_cycle.attr,
168 &dev_attr_enable.attr,
169 &dev_attr_polarity.attr,
170 NULL
171};
172
173static const struct attribute_group pwm_attr_group = {
174 .attrs = pwm_attrs,
175};
176
177static const struct attribute_group *pwm_attr_groups[] = {
178 &pwm_attr_group,
179 NULL,
180};
181
182static void pwm_export_release(struct device *child)
183{
184 struct pwm_export *export = child_to_pwm_export(child);
185
186 kfree(export);
187}
188
189static int pwm_export_child(struct device *parent, struct pwm_device *pwm)
190{
191 struct pwm_export *export;
192 int ret;
193
194 if (test_and_set_bit(PWMF_EXPORTED, &pwm->flags))
195 return -EBUSY;
196
197 export = kzalloc(sizeof(*export), GFP_KERNEL);
198 if (!export) {
199 clear_bit(PWMF_EXPORTED, &pwm->flags);
200 return -ENOMEM;
201 }
202
203 export->pwm = pwm;
204
205 export->child.release = pwm_export_release;
206 export->child.parent = parent;
207 export->child.devt = MKDEV(0, 0);
208 export->child.groups = pwm_attr_groups;
209 dev_set_name(&export->child, "pwm%u", pwm->hwpwm);
210
211 ret = device_register(&export->child);
212 if (ret) {
213 clear_bit(PWMF_EXPORTED, &pwm->flags);
214 kfree(export);
215 return ret;
216 }
217
218 return 0;
219}
220
221static int pwm_unexport_match(struct device *child, void *data)
222{
223 return child_to_pwm_device(child) == data;
224}
225
226static int pwm_unexport_child(struct device *parent, struct pwm_device *pwm)
227{
228 struct device *child;
229
230 if (!test_and_clear_bit(PWMF_EXPORTED, &pwm->flags))
231 return -ENODEV;
232
233 child = device_find_child(parent, pwm, pwm_unexport_match);
234 if (!child)
235 return -ENODEV;
236
237 /* for device_find_child() */
238 put_device(child);
239 device_unregister(child);
240 pwm_put(pwm);
241
242 return 0;
243}
244
245static ssize_t pwm_export_store(struct device *parent,
246 struct device_attribute *attr,
247 const char *buf, size_t len)
248{
249 struct pwm_chip *chip = dev_get_drvdata(parent);
250 struct pwm_device *pwm;
251 unsigned int hwpwm;
252 int ret;
253
254 ret = kstrtouint(buf, 0, &hwpwm);
255 if (ret < 0)
256 return ret;
257
258 if (hwpwm >= chip->npwm)
259 return -ENODEV;
260
261 pwm = pwm_request_from_chip(chip, hwpwm, "sysfs");
262 if (IS_ERR(pwm))
263 return PTR_ERR(pwm);
264
265 ret = pwm_export_child(parent, pwm);
266 if (ret < 0)
267 pwm_put(pwm);
268
269 return ret ? : len;
270}
271
272static ssize_t pwm_unexport_store(struct device *parent,
273 struct device_attribute *attr,
274 const char *buf, size_t len)
275{
276 struct pwm_chip *chip = dev_get_drvdata(parent);
277 unsigned int hwpwm;
278 int ret;
279
280 ret = kstrtouint(buf, 0, &hwpwm);
281 if (ret < 0)
282 return ret;
283
284 if (hwpwm >= chip->npwm)
285 return -ENODEV;
286
287 ret = pwm_unexport_child(parent, &chip->pwms[hwpwm]);
288
289 return ret ? : len;
290}
291
292static ssize_t pwm_npwm_show(struct device *parent,
293 struct device_attribute *attr,
294 char *buf)
295{
296 const struct pwm_chip *chip = dev_get_drvdata(parent);
297
298 return sprintf(buf, "%u\n", chip->npwm);
299}
300
301static struct device_attribute pwm_chip_attrs[] = {
302 __ATTR(export, 0200, NULL, pwm_export_store),
303 __ATTR(unexport, 0200, NULL, pwm_unexport_store),
304 __ATTR(npwm, 0444, pwm_npwm_show, NULL),
305 __ATTR_NULL,
306};
307
308static struct class pwm_class = {
309 .name = "pwm",
310 .owner = THIS_MODULE,
311 .dev_attrs = pwm_chip_attrs,
312};
313
314static int pwmchip_sysfs_match(struct device *parent, const void *data)
315{
316 return dev_get_drvdata(parent) == data;
317}
318
319void pwmchip_sysfs_export(struct pwm_chip *chip)
320{
321 struct device *parent;
322
323 /*
324 * If device_create() fails the pwm_chip is still usable by
325 * the kernel its just not exported.
326 */
327 parent = device_create(&pwm_class, chip->dev, MKDEV(0, 0), chip,
328 "pwmchip%d", chip->base);
329 if (IS_ERR(parent)) {
330 dev_warn(chip->dev,
331 "device_create failed for pwm_chip sysfs export\n");
332 }
333}
334
335void pwmchip_sysfs_unexport(struct pwm_chip *chip)
336{
337 struct device *parent;
338
339 parent = class_find_device(&pwm_class, NULL, chip,
340 pwmchip_sysfs_match);
341 if (parent) {
342 /* for class_find_device() */
343 put_device(parent);
344 device_unregister(parent);
345 }
346}
347
348static int __init pwm_sysfs_init(void)
349{
350 return class_register(&pwm_class);
351}
352subsys_initcall(pwm_sysfs_init);