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 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_get_period(pwm));
 50}
 51
 52static ssize_t 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_get_duty_cycle(pwm), val);
 65
 66	return ret ? : size;
 67}
 68
 69static ssize_t 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_get_duty_cycle(pwm));
 76}
 77
 78static ssize_t 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_get_period(pwm));
 91
 92	return ret ? : size;
 93}
 94
 95static ssize_t 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
101	return sprintf(buf, "%d\n", pwm_is_enabled(pwm));
102}
103
104static ssize_t enable_store(struct device *child,
105			    struct device_attribute *attr,
106			    const char *buf, size_t size)
107{
108	struct pwm_device *pwm = child_to_pwm_device(child);
109	int val, ret;
110
111	ret = kstrtoint(buf, 0, &val);
112	if (ret)
113		return ret;
114
115	switch (val) {
116	case 0:
117		pwm_disable(pwm);
118		break;
119	case 1:
120		ret = pwm_enable(pwm);
121		break;
122	default:
123		ret = -EINVAL;
124		break;
125	}
126
127	return ret ? : size;
128}
129
130static ssize_t polarity_show(struct device *child,
131			     struct device_attribute *attr,
132			     char *buf)
133{
134	const struct pwm_device *pwm = child_to_pwm_device(child);
135	const char *polarity = "unknown";
136
137	switch (pwm_get_polarity(pwm)) {
138	case PWM_POLARITY_NORMAL:
139		polarity = "normal";
140		break;
141
142	case PWM_POLARITY_INVERSED:
143		polarity = "inversed";
144		break;
145	}
146
147	return sprintf(buf, "%s\n", polarity);
148}
149
150static ssize_t polarity_store(struct device *child,
151			      struct device_attribute *attr,
152			      const char *buf, size_t size)
153{
154	struct pwm_device *pwm = child_to_pwm_device(child);
155	enum pwm_polarity polarity;
156	int ret;
157
158	if (sysfs_streq(buf, "normal"))
159		polarity = PWM_POLARITY_NORMAL;
160	else if (sysfs_streq(buf, "inversed"))
161		polarity = PWM_POLARITY_INVERSED;
162	else
163		return -EINVAL;
164
165	ret = pwm_set_polarity(pwm, polarity);
166
167	return ret ? : size;
168}
169
170static DEVICE_ATTR_RW(period);
171static DEVICE_ATTR_RW(duty_cycle);
172static DEVICE_ATTR_RW(enable);
173static DEVICE_ATTR_RW(polarity);
174
175static struct attribute *pwm_attrs[] = {
176	&dev_attr_period.attr,
177	&dev_attr_duty_cycle.attr,
178	&dev_attr_enable.attr,
179	&dev_attr_polarity.attr,
180	NULL
181};
182ATTRIBUTE_GROUPS(pwm);
183
184static void pwm_export_release(struct device *child)
185{
186	struct pwm_export *export = child_to_pwm_export(child);
187
188	kfree(export);
189}
190
191static int pwm_export_child(struct device *parent, struct pwm_device *pwm)
192{
193	struct pwm_export *export;
194	int ret;
195
196	if (test_and_set_bit(PWMF_EXPORTED, &pwm->flags))
197		return -EBUSY;
198
199	export = kzalloc(sizeof(*export), GFP_KERNEL);
200	if (!export) {
201		clear_bit(PWMF_EXPORTED, &pwm->flags);
202		return -ENOMEM;
203	}
204
205	export->pwm = pwm;
206
207	export->child.release = pwm_export_release;
208	export->child.parent = parent;
209	export->child.devt = MKDEV(0, 0);
210	export->child.groups = pwm_groups;
211	dev_set_name(&export->child, "pwm%u", pwm->hwpwm);
212
213	ret = device_register(&export->child);
214	if (ret) {
215		clear_bit(PWMF_EXPORTED, &pwm->flags);
216		kfree(export);
217		return ret;
218	}
219
220	return 0;
221}
222
223static int pwm_unexport_match(struct device *child, void *data)
224{
225	return child_to_pwm_device(child) == data;
226}
227
228static int pwm_unexport_child(struct device *parent, struct pwm_device *pwm)
229{
230	struct device *child;
231
232	if (!test_and_clear_bit(PWMF_EXPORTED, &pwm->flags))
233		return -ENODEV;
234
235	child = device_find_child(parent, pwm, pwm_unexport_match);
236	if (!child)
237		return -ENODEV;
238
239	/* for device_find_child() */
240	put_device(child);
241	device_unregister(child);
242	pwm_put(pwm);
243
244	return 0;
245}
246
247static ssize_t export_store(struct device *parent,
248			    struct device_attribute *attr,
249			    const char *buf, size_t len)
250{
251	struct pwm_chip *chip = dev_get_drvdata(parent);
252	struct pwm_device *pwm;
253	unsigned int hwpwm;
254	int ret;
255
256	ret = kstrtouint(buf, 0, &hwpwm);
257	if (ret < 0)
258		return ret;
259
260	if (hwpwm >= chip->npwm)
261		return -ENODEV;
262
263	pwm = pwm_request_from_chip(chip, hwpwm, "sysfs");
264	if (IS_ERR(pwm))
265		return PTR_ERR(pwm);
266
267	ret = pwm_export_child(parent, pwm);
268	if (ret < 0)
269		pwm_put(pwm);
270
271	return ret ? : len;
272}
273static DEVICE_ATTR_WO(export);
274
275static ssize_t unexport_store(struct device *parent,
276			      struct device_attribute *attr,
277			      const char *buf, size_t len)
278{
279	struct pwm_chip *chip = dev_get_drvdata(parent);
280	unsigned int hwpwm;
281	int ret;
282
283	ret = kstrtouint(buf, 0, &hwpwm);
284	if (ret < 0)
285		return ret;
286
287	if (hwpwm >= chip->npwm)
288		return -ENODEV;
289
290	ret = pwm_unexport_child(parent, &chip->pwms[hwpwm]);
291
292	return ret ? : len;
293}
294static DEVICE_ATTR_WO(unexport);
295
296static ssize_t npwm_show(struct device *parent, struct device_attribute *attr,
297			 char *buf)
298{
299	const struct pwm_chip *chip = dev_get_drvdata(parent);
300
301	return sprintf(buf, "%u\n", chip->npwm);
302}
303static DEVICE_ATTR_RO(npwm);
304
305static struct attribute *pwm_chip_attrs[] = {
306	&dev_attr_export.attr,
307	&dev_attr_unexport.attr,
308	&dev_attr_npwm.attr,
309	NULL,
310};
311ATTRIBUTE_GROUPS(pwm_chip);
312
313static struct class pwm_class = {
314	.name = "pwm",
315	.owner = THIS_MODULE,
316	.dev_groups = pwm_chip_groups,
317};
318
319static int pwmchip_sysfs_match(struct device *parent, const void *data)
320{
321	return dev_get_drvdata(parent) == data;
322}
323
324void pwmchip_sysfs_export(struct pwm_chip *chip)
325{
326	struct device *parent;
327
328	/*
329	 * If device_create() fails the pwm_chip is still usable by
330	 * the kernel its just not exported.
331	 */
332	parent = device_create(&pwm_class, chip->dev, MKDEV(0, 0), chip,
333			       "pwmchip%d", chip->base);
334	if (IS_ERR(parent)) {
335		dev_warn(chip->dev,
336			 "device_create failed for pwm_chip sysfs export\n");
337	}
338}
339
340void pwmchip_sysfs_unexport(struct pwm_chip *chip)
341{
342	struct device *parent;
343
344	parent = class_find_device(&pwm_class, NULL, chip,
345				   pwmchip_sysfs_match);
346	if (parent) {
347		/* for class_find_device() */
348		put_device(parent);
349		device_unregister(parent);
350	}
351}
352
353static int __init pwm_sysfs_init(void)
354{
355	return class_register(&pwm_class);
356}
357subsys_initcall(pwm_sysfs_init);