[go: nahoru, domu]
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
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};
172ATTRIBUTE_GROUPS(pwm);
173
174static void pwm_export_release(struct device *child)
175{
176	struct pwm_export *export = child_to_pwm_export(child);
177
178	kfree(export);
179}
180
181static int pwm_export_child(struct device *parent, struct pwm_device *pwm)
182{
183	struct pwm_export *export;
184	int ret;
185
186	if (test_and_set_bit(PWMF_EXPORTED, &pwm->flags))
187		return -EBUSY;
188
189	export = kzalloc(sizeof(*export), GFP_KERNEL);
190	if (!export) {
191		clear_bit(PWMF_EXPORTED, &pwm->flags);
192		return -ENOMEM;
193	}
194
195	export->pwm = pwm;
196
197	export->child.release = pwm_export_release;
198	export->child.parent = parent;
199	export->child.devt = MKDEV(0, 0);
200	export->child.groups = pwm_groups;
201	dev_set_name(&export->child, "pwm%u", pwm->hwpwm);
202
203	ret = device_register(&export->child);
204	if (ret) {
205		clear_bit(PWMF_EXPORTED, &pwm->flags);
206		kfree(export);
207		return ret;
208	}
209
210	return 0;
211}
212
213static int pwm_unexport_match(struct device *child, void *data)
214{
215	return child_to_pwm_device(child) == data;
216}
217
218static int pwm_unexport_child(struct device *parent, struct pwm_device *pwm)
219{
220	struct device *child;
221
222	if (!test_and_clear_bit(PWMF_EXPORTED, &pwm->flags))
223		return -ENODEV;
224
225	child = device_find_child(parent, pwm, pwm_unexport_match);
226	if (!child)
227		return -ENODEV;
228
229	/* for device_find_child() */
230	put_device(child);
231	device_unregister(child);
232	pwm_put(pwm);
233
234	return 0;
235}
236
237static ssize_t pwm_export_store(struct device *parent,
238				struct device_attribute *attr,
239				const char *buf, size_t len)
240{
241	struct pwm_chip *chip = dev_get_drvdata(parent);
242	struct pwm_device *pwm;
243	unsigned int hwpwm;
244	int ret;
245
246	ret = kstrtouint(buf, 0, &hwpwm);
247	if (ret < 0)
248		return ret;
249
250	if (hwpwm >= chip->npwm)
251		return -ENODEV;
252
253	pwm = pwm_request_from_chip(chip, hwpwm, "sysfs");
254	if (IS_ERR(pwm))
255		return PTR_ERR(pwm);
256
257	ret = pwm_export_child(parent, pwm);
258	if (ret < 0)
259		pwm_put(pwm);
260
261	return ret ? : len;
262}
263static DEVICE_ATTR(export, 0200, NULL, pwm_export_store);
264
265static ssize_t pwm_unexport_store(struct device *parent,
266				  struct device_attribute *attr,
267				  const char *buf, size_t len)
268{
269	struct pwm_chip *chip = dev_get_drvdata(parent);
270	unsigned int hwpwm;
271	int ret;
272
273	ret = kstrtouint(buf, 0, &hwpwm);
274	if (ret < 0)
275		return ret;
276
277	if (hwpwm >= chip->npwm)
278		return -ENODEV;
279
280	ret = pwm_unexport_child(parent, &chip->pwms[hwpwm]);
281
282	return ret ? : len;
283}
284static DEVICE_ATTR(unexport, 0200, NULL, pwm_unexport_store);
285
286static ssize_t npwm_show(struct device *parent, struct device_attribute *attr,
287			 char *buf)
288{
289	const struct pwm_chip *chip = dev_get_drvdata(parent);
290
291	return sprintf(buf, "%u\n", chip->npwm);
292}
293static DEVICE_ATTR_RO(npwm);
294
295static struct attribute *pwm_chip_attrs[] = {
296	&dev_attr_export.attr,
297	&dev_attr_unexport.attr,
298	&dev_attr_npwm.attr,
299	NULL,
300};
301ATTRIBUTE_GROUPS(pwm_chip);
302
303static struct class pwm_class = {
304	.name		= "pwm",
305	.owner		= THIS_MODULE,
306	.dev_groups	= pwm_chip_groups,
307};
308
309static int pwmchip_sysfs_match(struct device *parent, const void *data)
310{
311	return dev_get_drvdata(parent) == data;
312}
313
314void pwmchip_sysfs_export(struct pwm_chip *chip)
315{
316	struct device *parent;
317
318	/*
319	 * If device_create() fails the pwm_chip is still usable by
320	 * the kernel its just not exported.
321	 */
322	parent = device_create(&pwm_class, chip->dev, MKDEV(0, 0), chip,
323			       "pwmchip%d", chip->base);
324	if (IS_ERR(parent)) {
325		dev_warn(chip->dev,
326			 "device_create failed for pwm_chip sysfs export\n");
327	}
328}
329
330void pwmchip_sysfs_unexport(struct pwm_chip *chip)
331{
332	struct device *parent;
333
334	parent = class_find_device(&pwm_class, NULL, chip,
335				   pwmchip_sysfs_match);
336	if (parent) {
337		/* for class_find_device() */
338		put_device(parent);
339		device_unregister(parent);
340	}
341}
342
343static int __init pwm_sysfs_init(void)
344{
345	return class_register(&pwm_class);
346}
347subsys_initcall(pwm_sysfs_init);
348