1 /*
2 * drivers/switch/switch_gpio.c
3 *
4 * Copyright (C) 2008 Google, Inc.
5 * Author: Mike Lockwood <lockwood@android.com>
6 *
7 * This software is licensed under the terms of the GNU General Public
8 * License version 2, as published by the Free Software Foundation, and
9 * may be copied, distributed, and modified under those terms.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 */
17
18 #include <linux/module.h>
19 #include <linux/kernel.h>
20 #include <linux/init.h>
21 #include <linux/interrupt.h>
22 #include <linux/platform_device.h>
23 #include <linux/switch.h>
24 #include <linux/workqueue.h>
25 #include <linux/gpio.h>
26
27 struct gpio_switch_data {
28 struct switch_dev sdev;
29 unsigned gpio;
30 const char *name_on;
31 const char *name_off;
32 const char *state_on;
33 const char *state_off;
34 int irq;
35 struct work_struct work;
36 };
37
gpio_switch_work(struct work_struct * work)38 static void gpio_switch_work(struct work_struct *work)
39 {
40 int state;
41 struct gpio_switch_data *data =
42 container_of(work, struct gpio_switch_data, work);
43
44 state = gpio_get_value(data->gpio);
45 switch_set_state(&data->sdev, state);
46 }
47
gpio_irq_handler(int irq,void * dev_id)48 static irqreturn_t gpio_irq_handler(int irq, void *dev_id)
49 {
50 struct gpio_switch_data *switch_data =
51 (struct gpio_switch_data *)dev_id;
52
53 schedule_work(&switch_data->work);
54 return IRQ_HANDLED;
55 }
56
switch_gpio_print_state(struct switch_dev * sdev,char * buf)57 static ssize_t switch_gpio_print_state(struct switch_dev *sdev, char *buf)
58 {
59 struct gpio_switch_data *switch_data =
60 container_of(sdev, struct gpio_switch_data, sdev);
61 const char *state;
62 if (switch_get_state(sdev))
63 state = switch_data->state_on;
64 else
65 state = switch_data->state_off;
66
67 if (state)
68 return sprintf(buf, "%s\n", state);
69 return -1;
70 }
71
gpio_switch_probe(struct platform_device * pdev)72 static int gpio_switch_probe(struct platform_device *pdev)
73 {
74 struct gpio_switch_platform_data *pdata = pdev->dev.platform_data;
75 struct gpio_switch_data *switch_data;
76 int ret = 0;
77
78 if (!pdata)
79 return -EBUSY;
80
81 switch_data = kzalloc(sizeof(struct gpio_switch_data), GFP_KERNEL);
82 if (!switch_data)
83 return -ENOMEM;
84
85 switch_data->sdev.name = pdata->name;
86 switch_data->gpio = pdata->gpio;
87 switch_data->name_on = pdata->name_on;
88 switch_data->name_off = pdata->name_off;
89 switch_data->state_on = pdata->state_on;
90 switch_data->state_off = pdata->state_off;
91 switch_data->sdev.print_state = switch_gpio_print_state;
92
93 ret = switch_dev_register(&switch_data->sdev);
94 if (ret < 0)
95 goto err_switch_dev_register;
96
97 ret = gpio_request(switch_data->gpio, pdev->name);
98 if (ret < 0)
99 goto err_request_gpio;
100
101 ret = gpio_direction_input(switch_data->gpio);
102 if (ret < 0)
103 goto err_set_gpio_input;
104
105 INIT_WORK(&switch_data->work, gpio_switch_work);
106
107 switch_data->irq = gpio_to_irq(switch_data->gpio);
108 if (switch_data->irq < 0) {
109 ret = switch_data->irq;
110 goto err_detect_irq_num_failed;
111 }
112
113 ret = request_irq(switch_data->irq, gpio_irq_handler,
114 IRQF_TRIGGER_LOW, pdev->name, switch_data);
115 if (ret < 0)
116 goto err_request_irq;
117
118 /* Perform initial detection */
119 gpio_switch_work(&switch_data->work);
120
121 return 0;
122
123 err_request_irq:
124 err_detect_irq_num_failed:
125 err_set_gpio_input:
126 gpio_free(switch_data->gpio);
127 err_request_gpio:
128 switch_dev_unregister(&switch_data->sdev);
129 err_switch_dev_register:
130 kfree(switch_data);
131
132 return ret;
133 }
134
gpio_switch_remove(struct platform_device * pdev)135 static int __devexit gpio_switch_remove(struct platform_device *pdev)
136 {
137 struct gpio_switch_data *switch_data = platform_get_drvdata(pdev);
138
139 cancel_work_sync(&switch_data->work);
140 gpio_free(switch_data->gpio);
141 switch_dev_unregister(&switch_data->sdev);
142 kfree(switch_data);
143
144 return 0;
145 }
146
147 static struct platform_driver gpio_switch_driver = {
148 .probe = gpio_switch_probe,
149 .remove = __devexit_p(gpio_switch_remove),
150 .driver = {
151 .name = "switch-gpio",
152 .owner = THIS_MODULE,
153 },
154 };
155
gpio_switch_init(void)156 static int __init gpio_switch_init(void)
157 {
158 return platform_driver_register(&gpio_switch_driver);
159 }
160
gpio_switch_exit(void)161 static void __exit gpio_switch_exit(void)
162 {
163 platform_driver_unregister(&gpio_switch_driver);
164 }
165
166 module_init(gpio_switch_init);
167 module_exit(gpio_switch_exit);
168
169 MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
170 MODULE_DESCRIPTION("GPIO Switch driver");
171 MODULE_LICENSE("GPL");
172