timed_gpio.c revision 0445f1548fc66a72f3b91cdbe8f26b120245efd1 
1/* drivers/misc/timed_gpio.c
2 *
3 * Copyright (C) 2008 Google, Inc.
4 * Author: Mike Lockwood <lockwood@android.com>
5 *
6 * This software is licensed under the terms of the GNU General Public
7 * License version 2, as published by the Free Software Foundation, and
8 * may be copied, distributed, and modified under those terms.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 * GNU General Public License for more details.
14 *
15 */
16
17#include <linux/module.h>
18#include <linux/platform_device.h>
19#include <linux/slab.h>
20#include <linux/hrtimer.h>
21#include <linux/err.h>
22#include <linux/gpio.h>
23
24#include "timed_output.h"
25#include "timed_gpio.h"
26
27
28struct timed_gpio_data {
29	struct timed_output_dev dev;
30	struct hrtimer timer;
31	spinlock_t lock;
32	unsigned 	gpio;
33	int 		max_timeout;
34	u8 		active_low;
35};
36
37static enum hrtimer_restart gpio_timer_func(struct hrtimer *timer)
38{
39	struct timed_gpio_data *data =
40		container_of(timer, struct timed_gpio_data, timer);
41
42	gpio_direction_output(data->gpio, data->active_low ? 1 : 0);
43	return HRTIMER_NORESTART;
44}
45
46static int gpio_get_time(struct timed_output_dev *dev)
47{
48	struct timed_gpio_data	*data =
49		container_of(dev, struct timed_gpio_data, dev);
50
51	if (hrtimer_active(&data->timer)) {
52		ktime_t r = hrtimer_get_remaining(&data->timer);
53		struct timeval t = ktime_to_timeval(r);
54		return t.tv_sec * 1000 + t.tv_usec / 1000;
55	} else
56		return 0;
57}
58
59static void gpio_enable(struct timed_output_dev *dev, int value)
60{
61	struct timed_gpio_data	*data =
62		container_of(dev, struct timed_gpio_data, dev);
63	unsigned long	flags;
64
65	spin_lock_irqsave(&data->lock, flags);
66
67	/* cancel previous timer and set GPIO according to value */
68	hrtimer_cancel(&data->timer);
69	gpio_direction_output(data->gpio, data->active_low ? !value : !!value);
70
71	if (value > 0) {
72		if (value > data->max_timeout)
73			value = data->max_timeout;
74
75		hrtimer_start(&data->timer,
76			ktime_set(value / 1000, (value % 1000) * 1000000),
77			HRTIMER_MODE_REL);
78	}
79
80	spin_unlock_irqrestore(&data->lock, flags);
81}
82
83static int timed_gpio_probe(struct platform_device *pdev)
84{
85	struct timed_gpio_platform_data *pdata = pdev->dev.platform_data;
86	struct timed_gpio *cur_gpio;
87	struct timed_gpio_data *gpio_data, *gpio_dat;
88	int i, j, ret = 0;
89
90	if (!pdata)
91		return -EBUSY;
92
93	gpio_data = kzalloc(sizeof(struct timed_gpio_data) * pdata->num_gpios,
94			GFP_KERNEL);
95	if (!gpio_data)
96		return -ENOMEM;
97
98	for (i = 0; i < pdata->num_gpios; i++) {
99		cur_gpio = &pdata->gpios[i];
100		gpio_dat = &gpio_data[i];
101
102		hrtimer_init(&gpio_dat->timer, CLOCK_MONOTONIC,
103				HRTIMER_MODE_REL);
104		gpio_dat->timer.function = gpio_timer_func;
105		spin_lock_init(&gpio_dat->lock);
106
107		gpio_dat->dev.name = cur_gpio->name;
108		gpio_dat->dev.get_time = gpio_get_time;
109		gpio_dat->dev.enable = gpio_enable;
110		ret = gpio_request(cur_gpio->gpio, cur_gpio->name);
111		if (ret >= 0) {
112			ret = timed_output_dev_register(&gpio_dat->dev);
113			if (ret < 0)
114				gpio_free(cur_gpio->gpio);
115		}
116		if (ret < 0) {
117			for (j = 0; j < i; j++) {
118				timed_output_dev_unregister(&gpio_data[i].dev);
119				gpio_free(gpio_data[i].gpio);
120			}
121			kfree(gpio_data);
122			return ret;
123		}
124
125		gpio_dat->gpio = cur_gpio->gpio;
126		gpio_dat->max_timeout = cur_gpio->max_timeout;
127		gpio_dat->active_low = cur_gpio->active_low;
128		gpio_direction_output(gpio_dat->gpio, gpio_dat->active_low);
129	}
130
131	platform_set_drvdata(pdev, gpio_data);
132
133	return 0;
134}
135
136static int timed_gpio_remove(struct platform_device *pdev)
137{
138	struct timed_gpio_platform_data *pdata = pdev->dev.platform_data;
139	struct timed_gpio_data *gpio_data = platform_get_drvdata(pdev);
140	int i;
141
142	for (i = 0; i < pdata->num_gpios; i++) {
143		timed_output_dev_unregister(&gpio_data[i].dev);
144		gpio_free(gpio_data[i].gpio);
145	}
146
147	kfree(gpio_data);
148
149	return 0;
150}
151
152static struct platform_driver timed_gpio_driver = {
153	.probe		= timed_gpio_probe,
154	.remove		= timed_gpio_remove,
155	.driver		= {
156		.name		= TIMED_GPIO_NAME,
157		.owner		= THIS_MODULE,
158	},
159};
160
161static int __init timed_gpio_init(void)
162{
163	return platform_driver_register(&timed_gpio_driver);
164}
165
166static void __exit timed_gpio_exit(void)
167{
168	platform_driver_unregister(&timed_gpio_driver);
169}
170
171module_init(timed_gpio_init);
172module_exit(timed_gpio_exit);
173
174MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
175MODULE_DESCRIPTION("timed gpio driver");
176MODULE_LICENSE("GPL");
177