timed_gpio.c revision 99f41131b8d82cde1a84fec5b93ce31632552f0b 
1/* drivers/android/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/hrtimer.h>
20#include <linux/err.h>
21#include <asm/arch/gpio.h>
22
23#include "android_timed_gpio.h"
24
25
26static struct class *timed_gpio_class;
27
28struct timed_gpio_data {
29	struct device *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 *gpio_data = container_of(timer, struct timed_gpio_data, timer);
40
41	gpio_direction_output(gpio_data->gpio, gpio_data->active_low ? 1 : 0);
42	return HRTIMER_NORESTART;
43}
44
45static ssize_t gpio_enable_show(struct device *dev, struct device_attribute *attr, char *buf)
46{
47	struct timed_gpio_data *gpio_data = dev_get_drvdata(dev);
48	int remaining;
49
50	if (hrtimer_active(&gpio_data->timer)) {
51		ktime_t r = hrtimer_get_remaining(&gpio_data->timer);
52		remaining = r.tv.sec * 1000 + r.tv.nsec / 1000000;
53	} else
54		remaining = 0;
55
56	return sprintf(buf, "%d\n", remaining);
57}
58
59static ssize_t gpio_enable_store(
60		struct device *dev, struct device_attribute *attr,
61		const char *buf, size_t size)
62{
63	struct timed_gpio_data *gpio_data = dev_get_drvdata(dev);
64	int value;
65	unsigned long	flags;
66
67	sscanf(buf, "%d", &value);
68
69	spin_lock_irqsave(&gpio_data->lock, flags);
70
71	/* cancel previous timer and set GPIO according to value */
72	hrtimer_cancel(&gpio_data->timer);
73	gpio_direction_output(gpio_data->gpio, gpio_data->active_low ? !value : !!value);
74
75	if (value > 0) {
76		if (value > gpio_data->max_timeout)
77			value = gpio_data->max_timeout;
78
79		hrtimer_start(&gpio_data->timer,
80						ktime_set(value / 1000, (value % 1000) * 1000000),
81						HRTIMER_MODE_REL);
82	}
83
84	spin_unlock_irqrestore(&gpio_data->lock, flags);
85
86	return size;
87}
88
89static DEVICE_ATTR(enable, S_IRUGO | S_IWUSR, gpio_enable_show, gpio_enable_store);
90
91static int android_timed_gpio_probe(struct platform_device *pdev)
92{
93	struct timed_gpio_platform_data *pdata = pdev->dev.platform_data;
94	struct timed_gpio *cur_gpio;
95	struct timed_gpio_data *gpio_data, *gpio_dat;
96	int i, ret = 0;
97
98	if (!pdata)
99		return -EBUSY;
100
101	gpio_data = kzalloc(sizeof(struct timed_gpio_data) * pdata->num_gpios, GFP_KERNEL);
102	if (!gpio_data)
103		return -ENOMEM;
104
105	for (i = 0; i < pdata->num_gpios; i++) {
106		cur_gpio = &pdata->gpios[i];
107		gpio_dat = &gpio_data[i];
108
109		hrtimer_init(&gpio_dat->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
110		gpio_dat->timer.function = gpio_timer_func;
111		spin_lock_init(&gpio_dat->lock);
112
113		gpio_dat->gpio = cur_gpio->gpio;
114		gpio_dat->max_timeout = cur_gpio->max_timeout;
115		gpio_dat->active_low = cur_gpio->active_low;
116		gpio_direction_output(gpio_dat->gpio, gpio_dat->active_low);
117
118		gpio_dat->dev = device_create(timed_gpio_class, &pdev->dev, 0, "%s", cur_gpio->name);
119		if (unlikely(IS_ERR(gpio_dat->dev)))
120			return PTR_ERR(gpio_dat->dev);
121
122		dev_set_drvdata(gpio_dat->dev, gpio_dat);
123		ret = device_create_file(gpio_dat->dev, &dev_attr_enable);
124		if (ret)
125			return ret;
126	}
127
128	platform_set_drvdata(pdev, gpio_data);
129
130	return 0;
131}
132
133static int android_timed_gpio_remove(struct platform_device *pdev)
134{
135	struct timed_gpio_platform_data *pdata = pdev->dev.platform_data;
136	struct timed_gpio_data *gpio_data = platform_get_drvdata(pdev);
137	int i;
138
139	for (i = 0; i < pdata->num_gpios; i++) {
140		device_remove_file(gpio_data[i].dev, &dev_attr_enable);
141		device_unregister(gpio_data[i].dev);
142	}
143
144	kfree(gpio_data);
145
146	return 0;
147}
148
149static struct platform_driver android_timed_gpio_driver = {
150	.probe		= android_timed_gpio_probe,
151	.remove		= android_timed_gpio_remove,
152	.driver		= {
153		.name		= "android-timed-gpio",
154		.owner		= THIS_MODULE,
155	},
156};
157
158static int __init android_timed_gpio_init(void)
159{
160	timed_gpio_class = class_create(THIS_MODULE, "timed_output");
161	if (IS_ERR(timed_gpio_class))
162		return PTR_ERR(timed_gpio_class);
163	return platform_driver_register(&android_timed_gpio_driver);
164}
165
166static void __exit android_timed_gpio_exit(void)
167{
168	class_destroy(timed_gpio_class);
169	platform_driver_unregister(&android_timed_gpio_driver);
170}
171
172module_init(android_timed_gpio_init);
173module_exit(android_timed_gpio_exit);
174
175MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
176MODULE_DESCRIPTION("Android timed gpio driver");
177MODULE_LICENSE("GPL");
178