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         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 };
  44
  45 static void gpio_extcon_work(struct work_struct *work)
  46 {
  47         int state;
  48         struct gpio_extcon_data *data =
  49                 container_of(to_delayed_work(work), struct gpio_extcon_data,
  50                              work);
  51
  52         state = gpio_get_value(data->gpio);
  53         if (data->gpio_active_low)
  54                 state = !state;
  55         extcon_set_state(&data->edev, state);
  56 }
  57
  58 static irqreturn_t gpio_irq_handler(int irq, void *dev_id)
  59 {
  60         struct gpio_extcon_data *extcon_data = dev_id;
  61
  62         queue_delayed_work(system_power_efficient_wq, &extcon_data->work,
  63                               extcon_data->debounce_jiffies);
  64         return IRQ_HANDLED;
  65 }
  66
  67 static ssize_t extcon_gpio_print_state(struct extcon_dev *edev, char *buf)
  68 {
  69         struct gpio_extcon_data *extcon_data =
  70                 container_of(edev, struct gpio_extcon_data, edev);
  71         const char *state;
  72         if (extcon_get_state(edev))
  73                 state = extcon_data->state_on;
  74         else
  75                 state = extcon_data->state_off;
  76
  77         if (state)
  78                 return sprintf(buf, "%s\n", state);
  79         return -EINVAL;
  80 }
  81
  82 static int gpio_extcon_probe(struct platform_device *pdev)
  83 {
  84         struct gpio_extcon_platform_data *pdata = dev_get_platdata(&pdev->dev);
  85         struct gpio_extcon_data *extcon_data;
  86         int ret;
  87
  88         if (!pdata)
  89                 return -EBUSY;
  90         if (!pdata->irq_flags) {
  91                 dev_err(&pdev->dev, "IRQ flag is not specified.\n");
  92                 return -EINVAL;
  93         }
  94
  95         extcon_data = devm_kzalloc(&pdev->dev, sizeof(struct gpio_extcon_data),
  96                                    GFP_KERNEL);
  97         if (!extcon_data)
  98                 return -ENOMEM;
  99
 100         extcon_data->edev.name = pdata->name;
 101         extcon_data->edev.dev.parent = &pdev->dev;
 102         extcon_data->gpio = pdata->gpio;
 103         extcon_data->gpio_active_low = pdata->gpio_active_low;
 104         extcon_data->state_on = pdata->state_on;
 105         extcon_data->state_off = pdata->state_off;
 106         if (pdata->state_on && pdata->state_off)
 107                 extcon_data->edev.print_state = extcon_gpio_print_state;
 108         if (pdata->debounce) {
 109                 ret = gpio_set_debounce(extcon_data->gpio,
 110                                         pdata->debounce * 1000);
 111                 if (ret < 0)
 112                         extcon_data->debounce_jiffies =
 113                                 msecs_to_jiffies(pdata->debounce);
 114         }
 115
 116         ret = extcon_dev_register(&extcon_data->edev);
 117         if (ret < 0)
 118                 return ret;
 119
 120         ret = devm_gpio_request_one(&pdev->dev, extcon_data->gpio, GPIOF_DIR_IN,
 121                                     pdev->name);
 122         if (ret < 0)
 123                 goto err;
 124
 125         INIT_DELAYED_WORK(&extcon_data->work, gpio_extcon_work);
 126
 127         extcon_data->irq = gpio_to_irq(extcon_data->gpio);
 128         if (extcon_data->irq < 0) {
 129                 ret = extcon_data->irq;
 130                 goto err;
 131         }
 132
 133         ret = request_any_context_irq(extcon_data->irq, gpio_irq_handler,
 134                                       pdata->irq_flags, pdev->name,
 135                                       extcon_data);
 136         if (ret < 0)
 137                 goto err;
 138
 139         platform_set_drvdata(pdev, extcon_data);
 140         /* Perform initial detection */
 141         gpio_extcon_work(&extcon_data->work.work);
 142
 143         return 0;
 144
 145 err:
 146         extcon_dev_unregister(&extcon_data->edev);
 147
 148         return ret;
 149 }
 150
 151 static int gpio_extcon_remove(struct platform_device *pdev)
 152 {
 153         struct gpio_extcon_data *extcon_data = platform_get_drvdata(pdev);
 154
 155         cancel_delayed_work_sync(&extcon_data->work);
 156         free_irq(extcon_data->irq, extcon_data);
 157         extcon_dev_unregister(&extcon_data->edev);
 158
 159         return 0;
 160 }
 161
 162 static struct platform_driver gpio_extcon_driver = {
 163         .probe          = gpio_extcon_probe,
 164         .remove         = gpio_extcon_remove,
 165         .driver         = {
 166                 .name   = "extcon-gpio",
 167                 .owner  = THIS_MODULE,
 168         },
 169 };
 170
 171 module_platform_driver(gpio_extcon_driver);
 172
 173 MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
 174 MODULE_DESCRIPTION("GPIO extcon driver");
 175 MODULE_LICENSE("GPL");