xref: /linux/drivers/extcon/extcon-gpio.c (revision b889fcf63cb62e7fdb7816565e28f44dbe4a76a5)
1 /*
2  *  drivers/extcon/extcon_gpio.c
3  *
4  *  Single-state GPIO extcon driver based on extcon class
5  *
6  * Copyright (C) 2008 Google, Inc.
7  * Author: Mike Lockwood <lockwood@android.com>
8  *
9  * Modified by MyungJoo Ham <myungjoo.ham@samsung.com> to support extcon
10  * (originally switch class is supported)
11  *
12  * This software is licensed under the terms of the GNU General Public
13  * License version 2, as published by the Free Software Foundation, and
14  * may be copied, distributed, and modified under those terms.
15  *
16  * This program is distributed in the hope that it will be useful,
17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19  * GNU General Public License for more details.
20  *
21 */
22 
23 #include <linux/module.h>
24 #include <linux/kernel.h>
25 #include <linux/init.h>
26 #include <linux/interrupt.h>
27 #include <linux/platform_device.h>
28 #include <linux/slab.h>
29 #include <linux/workqueue.h>
30 #include <linux/gpio.h>
31 #include <linux/extcon.h>
32 #include <linux/extcon/extcon_gpio.h>
33 
34 struct gpio_extcon_data {
35 	struct extcon_dev edev;
36 	unsigned gpio;
37 	const char *state_on;
38 	const char *state_off;
39 	int irq;
40 	struct delayed_work work;
41 	unsigned long debounce_jiffies;
42 };
43 
44 static void gpio_extcon_work(struct work_struct *work)
45 {
46 	int state;
47 	struct gpio_extcon_data	*data =
48 		container_of(to_delayed_work(work), struct gpio_extcon_data,
49 			     work);
50 
51 	state = gpio_get_value(data->gpio);
52 	extcon_set_state(&data->edev, state);
53 }
54 
55 static irqreturn_t gpio_irq_handler(int irq, void *dev_id)
56 {
57 	struct gpio_extcon_data *extcon_data = dev_id;
58 
59 	schedule_delayed_work(&extcon_data->work,
60 			      extcon_data->debounce_jiffies);
61 	return IRQ_HANDLED;
62 }
63 
64 static ssize_t extcon_gpio_print_state(struct extcon_dev *edev, char *buf)
65 {
66 	struct gpio_extcon_data	*extcon_data =
67 		container_of(edev, struct gpio_extcon_data, edev);
68 	const char *state;
69 	if (extcon_get_state(edev))
70 		state = extcon_data->state_on;
71 	else
72 		state = extcon_data->state_off;
73 
74 	if (state)
75 		return sprintf(buf, "%s\n", state);
76 	return -EINVAL;
77 }
78 
79 static int gpio_extcon_probe(struct platform_device *pdev)
80 {
81 	struct gpio_extcon_platform_data *pdata = pdev->dev.platform_data;
82 	struct gpio_extcon_data *extcon_data;
83 	int ret = 0;
84 
85 	if (!pdata)
86 		return -EBUSY;
87 	if (!pdata->irq_flags) {
88 		dev_err(&pdev->dev, "IRQ flag is not specified.\n");
89 		return -EINVAL;
90 	}
91 
92 	extcon_data = devm_kzalloc(&pdev->dev, sizeof(struct gpio_extcon_data),
93 				   GFP_KERNEL);
94 	if (!extcon_data)
95 		return -ENOMEM;
96 
97 	extcon_data->edev.name = pdata->name;
98 	extcon_data->gpio = pdata->gpio;
99 	extcon_data->state_on = pdata->state_on;
100 	extcon_data->state_off = pdata->state_off;
101 	if (pdata->state_on && pdata->state_off)
102 		extcon_data->edev.print_state = extcon_gpio_print_state;
103 	extcon_data->debounce_jiffies = msecs_to_jiffies(pdata->debounce);
104 
105 	ret = extcon_dev_register(&extcon_data->edev, &pdev->dev);
106 	if (ret < 0)
107 		return ret;
108 
109 	ret = devm_gpio_request_one(&pdev->dev, extcon_data->gpio, GPIOF_DIR_IN,
110 				    pdev->name);
111 	if (ret < 0)
112 		goto err;
113 
114 	INIT_DELAYED_WORK(&extcon_data->work, gpio_extcon_work);
115 
116 	extcon_data->irq = gpio_to_irq(extcon_data->gpio);
117 	if (extcon_data->irq < 0) {
118 		ret = extcon_data->irq;
119 		goto err;
120 	}
121 
122 	ret = request_any_context_irq(extcon_data->irq, gpio_irq_handler,
123 				      pdata->irq_flags, pdev->name,
124 				      extcon_data);
125 	if (ret < 0)
126 		goto err;
127 
128 	platform_set_drvdata(pdev, extcon_data);
129 	/* Perform initial detection */
130 	gpio_extcon_work(&extcon_data->work.work);
131 
132 	return 0;
133 
134 err:
135 	extcon_dev_unregister(&extcon_data->edev);
136 
137 	return ret;
138 }
139 
140 static int gpio_extcon_remove(struct platform_device *pdev)
141 {
142 	struct gpio_extcon_data *extcon_data = platform_get_drvdata(pdev);
143 
144 	cancel_delayed_work_sync(&extcon_data->work);
145 	free_irq(extcon_data->irq, extcon_data);
146 	extcon_dev_unregister(&extcon_data->edev);
147 
148 	return 0;
149 }
150 
151 static struct platform_driver gpio_extcon_driver = {
152 	.probe		= gpio_extcon_probe,
153 	.remove		= gpio_extcon_remove,
154 	.driver		= {
155 		.name	= "extcon-gpio",
156 		.owner	= THIS_MODULE,
157 	},
158 };
159 
160 module_platform_driver(gpio_extcon_driver);
161 
162 MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
163 MODULE_DESCRIPTION("GPIO extcon driver");
164 MODULE_LICENSE("GPL");
165