summaryrefslogtreecommitdiff
path: root/drivers/pwm/core.c
blob: 0b8a38eca23ca36fc25f26e80fbec2d89e9ea0db (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
/*
 * Generic pwmlib implementation
 *
 * Copyright (C) 2011 Sascha Hauer <s.hauer@pengutronix.de>
 *
 *  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/list.h>
#include <linux/mutex.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/device.h>

struct pwm_device {
	struct			pwm_chip *chip;
	const char		*label;
	unsigned long		flags;
#define FLAG_REQUESTED	0
#define FLAG_ENABLED	1
	struct list_head	node;
};

static LIST_HEAD(pwm_list);

static DEFINE_MUTEX(pwm_lock);

static struct pwm_device *_find_pwm(int pwm_id)
{
	struct pwm_device *pwm;

	list_for_each_entry(pwm, &pwm_list, node) {
		if (pwm->chip->pwm_id == pwm_id)
			return pwm;
	}

	return NULL;
}

/**
 * pwmchip_add() - register a new PWM chip
 * @chip: the PWM chip to add
 */
int pwmchip_add(struct pwm_chip *chip)
{
	struct pwm_device *pwm;
	int ret = 0;

	pwm = kzalloc(sizeof(*pwm), GFP_KERNEL);
	if (!pwm)
		return -ENOMEM;

	pwm->chip = chip;

	mutex_lock(&pwm_lock);

	if (chip->pwm_id >= 0 && _find_pwm(chip->pwm_id)) {
		ret = -EBUSY;
		goto out;
	}

	list_add_tail(&pwm->node, &pwm_list);
out:
	mutex_unlock(&pwm_lock);

	if (ret)
		kfree(pwm);

	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)
{
	struct pwm_device *pwm;
	int ret = 0;

	mutex_lock(&pwm_lock);

	pwm = _find_pwm(chip->pwm_id);
	if (!pwm) {
		ret = -ENOENT;
		goto out;
	}

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

	list_del(&pwm->node);

	kfree(pwm);
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_id, const char *label)
{
	struct pwm_device *pwm;
	int ret;

	mutex_lock(&pwm_lock);

	pwm = _find_pwm(pwm_id);
	if (!pwm) {
		pwm = ERR_PTR(-ENOENT);
		goto out;
	}

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

	if (!try_module_get(pwm->chip->ops->owner)) {
		pwm = ERR_PTR(-ENODEV);
		goto out;
	}

	if (pwm->chip->ops->request) {
		ret = pwm->chip->ops->request(pwm->chip);
		if (ret) {
			pwm = ERR_PTR(ret);
			goto out_put;
		}
	}

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

	goto out;

out_put:
	module_put(pwm->chip->ops->owner);
out:
	mutex_unlock(&pwm_lock);

	return pwm;
}
EXPORT_SYMBOL_GPL(pwm_request);

/**
 * 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(FLAG_REQUESTED, &pwm->flags)) {
		pr_warning("PWM device already freed\n");
		goto out;
	}

	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)
{
	return pwm->chip->ops->config(pwm->chip, 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 (!test_and_set_bit(FLAG_ENABLED, &pwm->flags))
		return pwm->chip->ops->enable(pwm->chip);

	return 0;
}
EXPORT_SYMBOL_GPL(pwm_enable);

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