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Linux/drivers/extcon/extcon-gpio.c

  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/extcon.h>
 24 #include <linux/extcon/extcon-gpio.h>
 25 #include <linux/gpio.h>
 26 #include <linux/init.h>
 27 #include <linux/interrupt.h>
 28 #include <linux/kernel.h>
 29 #include <linux/module.h>
 30 #include <linux/platform_device.h>
 31 #include <linux/slab.h>
 32 #include <linux/workqueue.h>
 33 
 34 struct gpio_extcon_data {
 35         struct extcon_dev *edev;
 36         unsigned gpio;
 37         bool gpio_active_low;
 38         const char *state_on;
 39         const char *state_off;
 40         int irq;
 41         struct delayed_work work;
 42         unsigned long debounce_jiffies;
 43         bool check_on_resume;
 44 };
 45 
 46 static void gpio_extcon_work(struct work_struct *work)
 47 {
 48         int state;
 49         struct gpio_extcon_data *data =
 50                 container_of(to_delayed_work(work), struct gpio_extcon_data,
 51                              work);
 52 
 53         state = gpio_get_value(data->gpio);
 54         if (data->gpio_active_low)
 55                 state = !state;
 56         extcon_set_state(data->edev, state);
 57 }
 58 
 59 static irqreturn_t gpio_irq_handler(int irq, void *dev_id)
 60 {
 61         struct gpio_extcon_data *extcon_data = dev_id;
 62 
 63         queue_delayed_work(system_power_efficient_wq, &extcon_data->work,
 64                               extcon_data->debounce_jiffies);
 65         return IRQ_HANDLED;
 66 }
 67 
 68 static ssize_t extcon_gpio_print_state(struct extcon_dev *edev, char *buf)
 69 {
 70         struct device *dev = edev->dev.parent;
 71         struct gpio_extcon_data *extcon_data = dev_get_drvdata(dev);
 72         const char *state;
 73 
 74         if (extcon_get_state(edev))
 75                 state = extcon_data->state_on;
 76         else
 77                 state = extcon_data->state_off;
 78 
 79         if (state)
 80                 return sprintf(buf, "%s\n", state);
 81         return -EINVAL;
 82 }
 83 
 84 static int gpio_extcon_probe(struct platform_device *pdev)
 85 {
 86         struct gpio_extcon_platform_data *pdata = dev_get_platdata(&pdev->dev);
 87         struct gpio_extcon_data *extcon_data;
 88         int ret;
 89 
 90         if (!pdata)
 91                 return -EBUSY;
 92         if (!pdata->irq_flags) {
 93                 dev_err(&pdev->dev, "IRQ flag is not specified.\n");
 94                 return -EINVAL;
 95         }
 96 
 97         extcon_data = devm_kzalloc(&pdev->dev, sizeof(struct gpio_extcon_data),
 98                                    GFP_KERNEL);
 99         if (!extcon_data)
100                 return -ENOMEM;
101 
102         extcon_data->edev = devm_extcon_dev_allocate(&pdev->dev, NULL);
103         if (IS_ERR(extcon_data->edev)) {
104                 dev_err(&pdev->dev, "failed to allocate extcon device\n");
105                 return -ENOMEM;
106         }
107 
108         extcon_data->gpio = pdata->gpio;
109         extcon_data->gpio_active_low = pdata->gpio_active_low;
110         extcon_data->state_on = pdata->state_on;
111         extcon_data->state_off = pdata->state_off;
112         extcon_data->check_on_resume = pdata->check_on_resume;
113         if (pdata->state_on && pdata->state_off)
114                 extcon_data->edev->print_state = extcon_gpio_print_state;
115 
116         ret = devm_gpio_request_one(&pdev->dev, extcon_data->gpio, GPIOF_DIR_IN,
117                                     pdev->name);
118         if (ret < 0)
119                 return ret;
120 
121         if (pdata->debounce) {
122                 ret = gpio_set_debounce(extcon_data->gpio,
123                                         pdata->debounce * 1000);
124                 if (ret < 0)
125                         extcon_data->debounce_jiffies =
126                                 msecs_to_jiffies(pdata->debounce);
127         }
128 
129         ret = devm_extcon_dev_register(&pdev->dev, extcon_data->edev);
130         if (ret < 0)
131                 return ret;
132 
133         INIT_DELAYED_WORK(&extcon_data->work, gpio_extcon_work);
134 
135         extcon_data->irq = gpio_to_irq(extcon_data->gpio);
136         if (extcon_data->irq < 0)
137                 return extcon_data->irq;
138 
139         ret = request_any_context_irq(extcon_data->irq, gpio_irq_handler,
140                                       pdata->irq_flags, pdev->name,
141                                       extcon_data);
142         if (ret < 0)
143                 return ret;
144 
145         platform_set_drvdata(pdev, extcon_data);
146         /* Perform initial detection */
147         gpio_extcon_work(&extcon_data->work.work);
148 
149         return 0;
150 }
151 
152 static int gpio_extcon_remove(struct platform_device *pdev)
153 {
154         struct gpio_extcon_data *extcon_data = platform_get_drvdata(pdev);
155 
156         cancel_delayed_work_sync(&extcon_data->work);
157         free_irq(extcon_data->irq, extcon_data);
158 
159         return 0;
160 }
161 
162 #ifdef CONFIG_PM_SLEEP
163 static int gpio_extcon_resume(struct device *dev)
164 {
165         struct gpio_extcon_data *extcon_data;
166 
167         extcon_data = dev_get_drvdata(dev);
168         if (extcon_data->check_on_resume)
169                 queue_delayed_work(system_power_efficient_wq,
170                         &extcon_data->work, extcon_data->debounce_jiffies);
171 
172         return 0;
173 }
174 #endif
175 
176 static SIMPLE_DEV_PM_OPS(gpio_extcon_pm_ops, NULL, gpio_extcon_resume);
177 
178 static struct platform_driver gpio_extcon_driver = {
179         .probe          = gpio_extcon_probe,
180         .remove         = gpio_extcon_remove,
181         .driver         = {
182                 .name   = "extcon-gpio",
183                 .pm     = &gpio_extcon_pm_ops,
184         },
185 };
186 
187 module_platform_driver(gpio_extcon_driver);
188 
189 MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
190 MODULE_DESCRIPTION("GPIO extcon driver");
191 MODULE_LICENSE("GPL");
192 

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