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/workqueue.h>
  30#include <linux/gpio.h>
  31#include <linux/extcon.h>
  32#include <linux/extcon/extcon_gpio.h>
  33
  34struct 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
  44static 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
  55static 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
  64static 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
  79static int __devinit 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
 134err:
 135        extcon_dev_unregister(&extcon_data->edev);
 136
 137        return ret;
 138}
 139
 140static int __devexit 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
 151static struct platform_driver gpio_extcon_driver = {
 152        .probe          = gpio_extcon_probe,
 153        .remove         = __devexit_p(gpio_extcon_remove),
 154        .driver         = {
 155                .name   = "extcon-gpio",
 156                .owner  = THIS_MODULE,
 157        },
 158};
 159
 160module_platform_driver(gpio_extcon_driver);
 161
 162MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
 163MODULE_DESCRIPTION("GPIO extcon driver");
 164MODULE_LICENSE("GPL");
 165
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