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
28 struct 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
gpio_timer_func(struct hrtimer * timer)37 static 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
gpio_get_time(struct timed_output_dev * dev)46 static 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
gpio_enable(struct timed_output_dev * dev,int value)59 static 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
timed_gpio_probe(struct platform_device * pdev)83 static 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, ret;
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 goto err_out;
113 ret = timed_output_dev_register(&gpio_dat->dev);
114 if (ret < 0) {
115 gpio_free(cur_gpio->gpio);
116 goto err_out;
117 }
118
119 gpio_dat->gpio = cur_gpio->gpio;
120 gpio_dat->max_timeout = cur_gpio->max_timeout;
121 gpio_dat->active_low = cur_gpio->active_low;
122 gpio_direction_output(gpio_dat->gpio, gpio_dat->active_low);
123 }
124
125 platform_set_drvdata(pdev, gpio_data);
126
127 return 0;
128
129 err_out:
130 while (--i >= 0) {
131 timed_output_dev_unregister(&gpio_data[i].dev);
132 gpio_free(gpio_data[i].gpio);
133 }
134 kfree(gpio_data);
135
136 return ret;
137 }
138
timed_gpio_remove(struct platform_device * pdev)139 static int timed_gpio_remove(struct platform_device *pdev)
140 {
141 struct timed_gpio_platform_data *pdata = pdev->dev.platform_data;
142 struct timed_gpio_data *gpio_data = platform_get_drvdata(pdev);
143 int i;
144
145 for (i = 0; i < pdata->num_gpios; i++) {
146 timed_output_dev_unregister(&gpio_data[i].dev);
147 gpio_free(gpio_data[i].gpio);
148 }
149
150 kfree(gpio_data);
151
152 return 0;
153 }
154
155 static struct platform_driver timed_gpio_driver = {
156 .probe = timed_gpio_probe,
157 .remove = timed_gpio_remove,
158 .driver = {
159 .name = TIMED_GPIO_NAME,
160 .owner = THIS_MODULE,
161 },
162 };
163
timed_gpio_init(void)164 static int __init timed_gpio_init(void)
165 {
166 return platform_driver_register(&timed_gpio_driver);
167 }
168
timed_gpio_exit(void)169 static void __exit timed_gpio_exit(void)
170 {
171 platform_driver_unregister(&timed_gpio_driver);
172 }
173
174 module_init(timed_gpio_init);
175 module_exit(timed_gpio_exit);
176
177 MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
178 MODULE_DESCRIPTION("timed gpio driver");
179 MODULE_LICENSE("GPL");
180