linux/drivers/extcon/extcon_gpio.c
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   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/extcon.h>
  30#include <linux/workqueue.h>
  31#include <linux/gpio.h>
  32#include <linux/extcon.h>
  33#include <linux/extcon/extcon_gpio.h>
  34
  35struct gpio_extcon_data {
  36        struct extcon_dev edev;
  37        unsigned gpio;
  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
  45static 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        extcon_set_state(&data->edev, state);
  54}
  55
  56static irqreturn_t gpio_irq_handler(int irq, void *dev_id)
  57{
  58        struct gpio_extcon_data *extcon_data = dev_id;
  59
  60        schedule_delayed_work(&extcon_data->work,
  61                              extcon_data->debounce_jiffies);
  62        return IRQ_HANDLED;
  63}
  64
  65static ssize_t extcon_gpio_print_state(struct extcon_dev *edev, char *buf)
  66{
  67        struct gpio_extcon_data *extcon_data =
  68                container_of(edev, struct gpio_extcon_data, edev);
  69        const char *state;
  70        if (extcon_get_state(edev))
  71                state = extcon_data->state_on;
  72        else
  73                state = extcon_data->state_off;
  74
  75        if (state)
  76                return sprintf(buf, "%s\n", state);
  77        return -EINVAL;
  78}
  79
  80static int __devinit gpio_extcon_probe(struct platform_device *pdev)
  81{
  82        struct gpio_extcon_platform_data *pdata = pdev->dev.platform_data;
  83        struct gpio_extcon_data *extcon_data;
  84        int ret = 0;
  85
  86        if (!pdata)
  87                return -EBUSY;
  88        if (!pdata->irq_flags) {
  89                dev_err(&pdev->dev, "IRQ flag is not specified.\n");
  90                return -EINVAL;
  91        }
  92
  93        extcon_data = devm_kzalloc(&pdev->dev, sizeof(struct gpio_extcon_data),
  94                                   GFP_KERNEL);
  95        if (!extcon_data)
  96                return -ENOMEM;
  97
  98        extcon_data->edev.name = pdata->name;
  99        extcon_data->gpio = pdata->gpio;
 100        extcon_data->state_on = pdata->state_on;
 101        extcon_data->state_off = pdata->state_off;
 102        if (pdata->state_on && pdata->state_off)
 103                extcon_data->edev.print_state = extcon_gpio_print_state;
 104        extcon_data->debounce_jiffies = msecs_to_jiffies(pdata->debounce);
 105
 106        ret = extcon_dev_register(&extcon_data->edev, &pdev->dev);
 107        if (ret < 0)
 108                return ret;
 109
 110        ret = devm_gpio_request_one(&pdev->dev, extcon_data->gpio, GPIOF_DIR_IN,
 111                                    pdev->name);
 112        if (ret < 0)
 113                goto err;
 114
 115        INIT_DELAYED_WORK(&extcon_data->work, gpio_extcon_work);
 116
 117        extcon_data->irq = gpio_to_irq(extcon_data->gpio);
 118        if (extcon_data->irq < 0) {
 119                ret = extcon_data->irq;
 120                goto err;
 121        }
 122
 123        ret = request_any_context_irq(extcon_data->irq, gpio_irq_handler,
 124                                      pdata->irq_flags, pdev->name,
 125                                      extcon_data);
 126        if (ret < 0)
 127                goto err;
 128
 129        platform_set_drvdata(pdev, extcon_data);
 130        /* Perform initial detection */
 131        gpio_extcon_work(&extcon_data->work.work);
 132
 133        return 0;
 134
 135err:
 136        extcon_dev_unregister(&extcon_data->edev);
 137
 138        return ret;
 139}
 140
 141static int __devexit gpio_extcon_remove(struct platform_device *pdev)
 142{
 143        struct gpio_extcon_data *extcon_data = platform_get_drvdata(pdev);
 144
 145        cancel_delayed_work_sync(&extcon_data->work);
 146        free_irq(extcon_data->irq, extcon_data);
 147        extcon_dev_unregister(&extcon_data->edev);
 148
 149        return 0;
 150}
 151
 152static struct platform_driver gpio_extcon_driver = {
 153        .probe          = gpio_extcon_probe,
 154        .remove         = __devexit_p(gpio_extcon_remove),
 155        .driver         = {
 156                .name   = "extcon-gpio",
 157                .owner  = THIS_MODULE,
 158        },
 159};
 160
 161module_platform_driver(gpio_extcon_driver);
 162
 163MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
 164MODULE_DESCRIPTION("GPIO extcon driver");
 165MODULE_LICENSE("GPL");
 166
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