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
55 return t.tv_sec * 1000 + t.tv_usec / 1000;
56 } else
57 return 0;
58 }
59
gpio_enable(struct timed_output_dev * dev,int value)60 static void gpio_enable(struct timed_output_dev *dev, int value)
61 {
62 struct timed_gpio_data *data =
63 container_of(dev, struct timed_gpio_data, dev);
64 unsigned long flags;
65
66 spin_lock_irqsave(&data->lock, flags);
67
68 /* cancel previous timer and set GPIO according to value */
69 hrtimer_cancel(&data->timer);
70 gpio_direction_output(data->gpio, data->active_low ? !value : !!value);
71
72 if (value > 0) {
73 if (value > data->max_timeout)
74 value = data->max_timeout;
75
76 hrtimer_start(&data->timer,
77 ktime_set(value / 1000, (value % 1000) * 1000000),
78 HRTIMER_MODE_REL);
79 }
80
81 spin_unlock_irqrestore(&data->lock, flags);
82 }
83
timed_gpio_probe(struct platform_device * pdev)84 static int timed_gpio_probe(struct platform_device *pdev)
85 {
86 struct timed_gpio_platform_data *pdata = pdev->dev.platform_data;
87 struct timed_gpio *cur_gpio;
88 struct timed_gpio_data *gpio_data, *gpio_dat;
89 int i, ret;
90
91 if (!pdata)
92 return -EBUSY;
93
94 gpio_data = kzalloc(sizeof(struct timed_gpio_data) * pdata->num_gpios,
95 GFP_KERNEL);
96 if (!gpio_data)
97 return -ENOMEM;
98
99 for (i = 0; i < pdata->num_gpios; i++) {
100 cur_gpio = &pdata->gpios[i];
101 gpio_dat = &gpio_data[i];
102
103 hrtimer_init(&gpio_dat->timer, CLOCK_MONOTONIC,
104 HRTIMER_MODE_REL);
105 gpio_dat->timer.function = gpio_timer_func;
106 spin_lock_init(&gpio_dat->lock);
107
108 gpio_dat->dev.name = cur_gpio->name;
109 gpio_dat->dev.get_time = gpio_get_time;
110 gpio_dat->dev.enable = gpio_enable;
111 ret = gpio_request(cur_gpio->gpio, cur_gpio->name);
112 if (ret < 0)
113 goto err_out;
114 ret = timed_output_dev_register(&gpio_dat->dev);
115 if (ret < 0) {
116 gpio_free(cur_gpio->gpio);
117 goto err_out;
118 }
119
120 gpio_dat->gpio = cur_gpio->gpio;
121 gpio_dat->max_timeout = cur_gpio->max_timeout;
122 gpio_dat->active_low = cur_gpio->active_low;
123 gpio_direction_output(gpio_dat->gpio, gpio_dat->active_low);
124 }
125
126 platform_set_drvdata(pdev, gpio_data);
127
128 return 0;
129
130 err_out:
131 while (--i >= 0) {
132 timed_output_dev_unregister(&gpio_data[i].dev);
133 gpio_free(gpio_data[i].gpio);
134 }
135 kfree(gpio_data);
136
137 return ret;
138 }
139
timed_gpio_remove(struct platform_device * pdev)140 static int timed_gpio_remove(struct platform_device *pdev)
141 {
142 struct timed_gpio_platform_data *pdata = pdev->dev.platform_data;
143 struct timed_gpio_data *gpio_data = platform_get_drvdata(pdev);
144 int i;
145
146 for (i = 0; i < pdata->num_gpios; i++) {
147 timed_output_dev_unregister(&gpio_data[i].dev);
148 gpio_free(gpio_data[i].gpio);
149 }
150
151 kfree(gpio_data);
152
153 return 0;
154 }
155
156 static struct platform_driver timed_gpio_driver = {
157 .probe = timed_gpio_probe,
158 .remove = timed_gpio_remove,
159 .driver = {
160 .name = TIMED_GPIO_NAME,
161 .owner = THIS_MODULE,
162 },
163 };
164
165 module_platform_driver(timed_gpio_driver);
166
167 MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
168 MODULE_DESCRIPTION("timed gpio driver");
169 MODULE_LICENSE("GPL");
170