summaryrefslogtreecommitdiff
path: root/drivers/pwm/core.c
blob: aadc1d79744962442d8a6b632aa96691bd421320 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
/*
 * Generic pwmlib implementation
 *
 * Copyright (C) 2011 Sascha Hauer <s.hauer@pengutronix.de>
 * Copyright (C) 2011-2012 Avionic Design GmbH
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2, or (at your option)
 *  any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; see the file COPYING.  If not, write to
 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/module.h>
#include <linux/pwm.h>
#include <linux/radix-tree.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>

#define MAX_PWMS 1024

static DEFINE_MUTEX(pwm_lock);
static LIST_HEAD(pwm_chips);
static DECLARE_BITMAP(allocated_pwms, MAX_PWMS);
static RADIX_TREE(pwm_tree, GFP_KERNEL);

static struct pwm_device *pwm_to_device(unsigned int pwm)
{
	return radix_tree_lookup(&pwm_tree, pwm);
}

static int alloc_pwms(int pwm, unsigned int count)
{
	unsigned int from = 0;
	unsigned int start;

	if (pwm >= MAX_PWMS)
		return -EINVAL;

	if (pwm >= 0)
		from = pwm;

	start = bitmap_find_next_zero_area(allocated_pwms, MAX_PWMS, from,
					   count, 0);

	if (pwm >= 0 && start != pwm)
		return -EEXIST;

	if (start + count > MAX_PWMS)
		return -ENOSPC;

	return start;
}

static void free_pwms(struct pwm_chip *chip)
{
	unsigned int i;

	for (i = 0; i < chip->npwm; i++) {
		struct pwm_device *pwm = &chip->pwms[i];
		radix_tree_delete(&pwm_tree, pwm->pwm);
	}

	bitmap_clear(allocated_pwms, chip->base, chip->npwm);

	kfree(chip->pwms);
	chip->pwms = NULL;
}

static int pwm_device_request(struct pwm_device *pwm, const char *label)
{
	int err;

	if (test_bit(PWMF_REQUESTED, &pwm->flags))
		return -EBUSY;

	if (!try_module_get(pwm->chip->ops->owner))
		return -ENODEV;

	if (pwm->chip->ops->request) {
		err = pwm->chip->ops->request(pwm->chip, pwm);
		if (err) {
			module_put(pwm->chip->ops->owner);
			return err;
		}
	}

	set_bit(PWMF_REQUESTED, &pwm->flags);
	pwm->label = label;

	return 0;
}

/**
 * pwm_set_chip_data() - set private chip data for a PWM
 * @pwm: PWM device
 * @data: pointer to chip-specific data
 */
int pwm_set_chip_data(struct pwm_device *pwm, void *data)
{
	if (!pwm)
		return -EINVAL;

	pwm->chip_data = data;

	return 0;
}

/**
 * pwm_get_chip_data() - get private chip data for a PWM
 * @pwm: PWM device
 */
void *pwm_get_chip_data(struct pwm_device *pwm)
{
	return pwm ? pwm->chip_data : NULL;
}

/**
 * pwmchip_add() - register a new PWM chip
 * @chip: the PWM chip to add
 *
 * Register a new PWM chip. If chip->base < 0 then a dynamically assigned base
 * will be used.
 */
int pwmchip_add(struct pwm_chip *chip)
{
	struct pwm_device *pwm;
	unsigned int i;
	int ret;

	if (!chip || !chip->dev || !chip->ops || !chip->ops->config ||
	    !chip->ops->enable || !chip->ops->disable)
		return -EINVAL;

	mutex_lock(&pwm_lock);

	ret = alloc_pwms(chip->base, chip->npwm);
	if (ret < 0)
		goto out;

	chip->pwms = kzalloc(chip->npwm * sizeof(*pwm), GFP_KERNEL);
	if (!chip->pwms) {
		ret = -ENOMEM;
		goto out;
	}

	chip->base = ret;

	for (i = 0; i < chip->npwm; i++) {
		pwm = &chip->pwms[i];

		pwm->chip = chip;
		pwm->pwm = chip->base + i;
		pwm->hwpwm = i;

		radix_tree_insert(&pwm_tree, pwm->pwm, pwm);
	}

	bitmap_set(allocated_pwms, chip->base, chip->npwm);

	INIT_LIST_HEAD(&chip->list);
	list_add(&chip->list, &pwm_chips);

	ret = 0;

out:
	mutex_unlock(&pwm_lock);
	return ret;
}
EXPORT_SYMBOL_GPL(pwmchip_add);

/**
 * pwmchip_remove() - remove a PWM chip
 * @chip: the PWM chip to remove
 *
 * Removes a PWM chip. This function may return busy if the PWM chip provides
 * a PWM device that is still requested.
 */
int pwmchip_remove(struct pwm_chip *chip)
{
	unsigned int i;
	int ret = 0;

	mutex_lock(&pwm_lock);

	for (i = 0; i < chip->npwm; i++) {
		struct pwm_device *pwm = &chip->pwms[i];

		if (test_bit(PWMF_REQUESTED, &pwm->flags)) {
			ret = -EBUSY;
			goto out;
		}
	}

	list_del_init(&chip->list);
	free_pwms(chip);

out:
	mutex_unlock(&pwm_lock);
	return ret;
}
EXPORT_SYMBOL_GPL(pwmchip_remove);

/**
 * pwm_request() - request a PWM device
 * @pwm_id: global PWM device index
 * @label: PWM device label
 */
struct pwm_device *pwm_request(int pwm, const char *label)
{
	struct pwm_device *dev;
	int err;

	if (pwm < 0 || pwm >= MAX_PWMS)
		return ERR_PTR(-EINVAL);

	mutex_lock(&pwm_lock);

	dev = pwm_to_device(pwm);
	if (!dev) {
		dev = ERR_PTR(-EPROBE_DEFER);
		goto out;
	}

	err = pwm_device_request(dev, label);
	if (err < 0)
		dev = ERR_PTR(err);

out:
	mutex_unlock(&pwm_lock);

	return dev;
}
EXPORT_SYMBOL_GPL(pwm_request);

/**
 * pwm_request_from_chip() - request a PWM device relative to a PWM chip
 * @chip: PWM chip
 * @index: per-chip index of the PWM to request
 * @label: a literal description string of this PWM
 *
 * Returns the PWM at the given index of the given PWM chip. A negative error
 * code is returned if the index is not valid for the specified PWM chip or
 * if the PWM device cannot be requested.
 */
struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
					 unsigned int index,
					 const char *label)
{
	struct pwm_device *pwm;
	int err;

	if (!chip || index >= chip->npwm)
		return ERR_PTR(-EINVAL);

	mutex_lock(&pwm_lock);
	pwm = &chip->pwms[index];

	err = pwm_device_request(pwm, label);
	if (err < 0)
		pwm = ERR_PTR(err);

	mutex_unlock(&pwm_lock);
	return pwm;
}
EXPORT_SYMBOL_GPL(pwm_request_from_chip);

/**
 * pwm_free() - free a PWM device
 * @pwm: PWM device
 */
void pwm_free(struct pwm_device *pwm)
{
	mutex_lock(&pwm_lock);

	if (!test_and_clear_bit(PWMF_REQUESTED, &pwm->flags)) {
		pr_warning("PWM device already freed\n");
		goto out;
	}

	if (pwm->chip->ops->free)
		pwm->chip->ops->free(pwm->chip, pwm);

	pwm->label = NULL;

	module_put(pwm->chip->ops->owner);
out:
	mutex_unlock(&pwm_lock);
}
EXPORT_SYMBOL_GPL(pwm_free);

/**
 * pwm_config() - change a PWM device configuration
 * @pwm: PWM device
 * @duty_ns: "on" time (in nanoseconds)
 * @period_ns: duration (in nanoseconds) of one cycle
 */
int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
{
	if (!pwm || period_ns == 0 || duty_ns > period_ns)
		return -EINVAL;

	return pwm->chip->ops->config(pwm->chip, pwm, duty_ns, period_ns);
}
EXPORT_SYMBOL_GPL(pwm_config);

/**
 * pwm_enable() - start a PWM output toggling
 * @pwm: PWM device
 */
int pwm_enable(struct pwm_device *pwm)
{
	if (pwm && !test_and_set_bit(PWMF_ENABLED, &pwm->flags))
		return pwm->chip->ops->enable(pwm->chip, pwm);

	return pwm ? 0 : -EINVAL;
}
EXPORT_SYMBOL_GPL(pwm_enable);

/**
 * pwm_disable() - stop a PWM output toggling
 * @pwm: PWM device
 */
void pwm_disable(struct pwm_device *pwm)
{
	if (pwm && test_and_clear_bit(PWMF_ENABLED, &pwm->flags))
		pwm->chip->ops->disable(pwm->chip, pwm);
}
EXPORT_SYMBOL_GPL(pwm_disable);

#ifdef CONFIG_DEBUG_FS
static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s)
{
	unsigned int i;

	for (i = 0; i < chip->npwm; i++) {
		struct pwm_device *pwm = &chip->pwms[i];

		seq_printf(s, " pwm-%-3d (%-20.20s):", i, pwm->label);

		if (test_bit(PWMF_REQUESTED, &pwm->flags))
			seq_printf(s, " requested");

		if (test_bit(PWMF_ENABLED, &pwm->flags))
			seq_printf(s, " enabled");

		seq_printf(s, "\n");
	}
}

static void *pwm_seq_start(struct seq_file *s, loff_t *pos)
{
	mutex_lock(&pwm_lock);
	s->private = "";

	return seq_list_start(&pwm_chips, *pos);
}

static void *pwm_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
	s->private = "\n";

	return seq_list_next(v, &pwm_chips, pos);
}

static void pwm_seq_stop(struct seq_file *s, void *v)
{
	mutex_unlock(&pwm_lock);
}

static int pwm_seq_show(struct seq_file *s, void *v)
{
	struct pwm_chip *chip = list_entry(v, struct pwm_chip, list);

	seq_printf(s, "%s%s/%s, %d PWM device%s\n", (char *)s->private,
		   chip->dev->bus ? chip->dev->bus->name : "no-bus",
		   dev_name(chip->dev), chip->npwm,
		   (chip->npwm != 1) ? "s" : "");

	if (chip->ops->dbg_show)
		chip->ops->dbg_show(chip, s);
	else
		pwm_dbg_show(chip, s);

	return 0;
}

static const struct seq_operations pwm_seq_ops = {
	.start = pwm_seq_start,
	.next = pwm_seq_next,
	.stop = pwm_seq_stop,
	.show = pwm_seq_show,
};

static int pwm_seq_open(struct inode *inode, struct file *file)
{
	return seq_open(file, &pwm_seq_ops);
}

static const struct file_operations pwm_debugfs_ops = {
	.owner = THIS_MODULE,
	.open = pwm_seq_open,
	.read = seq_read,
	.llseek = seq_lseek,
	.release = seq_release,
};

static int __init pwm_debugfs_init(void)
{
	debugfs_create_file("pwm", S_IFREG | S_IRUGO, NULL, NULL,
			    &pwm_debugfs_ops);

	return 0;
}

subsys_initcall(pwm_debugfs_init);
#endif /* CONFIG_DEBUG_FS */