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/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");