extcon-gpio.c

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/*
 *  drivers/extcon/extcon_gpio.c
 *
 *  Single-state GPIO extcon driver based on extcon class
 *
 * Copyright (C) 2008 Google, Inc.
 * Author: Mike Lockwood <[email protected]>
 *
 * Modified by MyungJoo Ham <[email protected]> to support extcon
 * (originally switch class is supported)
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
*/

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <linux/gpio.h>
#include <linux/extcon.h>
#include <linux/extcon/extcon_gpio.h>

struct gpio_extcon_data {
    struct extcon_dev edev;
    unsigned gpio;
    const char *state_on;
    const char *state_off;
    int irq;
    struct delayed_work work;
    unsigned long debounce_jiffies;
};

static void gpio_extcon_work(struct work_struct *work)
{
    int state;
    struct gpio_extcon_data *data =
        container_of(to_delayed_work(work), struct gpio_extcon_data,
                 work);

    state = gpio_get_value(data->gpio);
    extcon_set_state(&data->edev, state);
}

static irqreturn_t gpio_irq_handler(int irq, void *dev_id)
{
    struct gpio_extcon_data *extcon_data = dev_id;

    schedule_delayed_work(&extcon_data->work,
                  extcon_data->debounce_jiffies);
    return IRQ_HANDLED;
}

static ssize_t extcon_gpio_print_state(struct extcon_dev *edev, char *buf)
{
    struct gpio_extcon_data *extcon_data =
        container_of(edev, struct gpio_extcon_data, edev);
    const char *state;
    if (extcon_get_state(edev))
        state = extcon_data->state_on;
    else
        state = extcon_data->state_off;

    if (state)
        return sprintf(buf, "%s\n", state);
    return -EINVAL;
}

static int __devinit gpio_extcon_probe(struct platform_device *pdev)
{
    struct gpio_extcon_platform_data *pdata = pdev->dev.platform_data;
    struct gpio_extcon_data *extcon_data;
    int ret = 0;

    if (!pdata)
        return -EBUSY;
    if (!pdata->irq_flags) {
        dev_err(&pdev->dev, "IRQ flag is not specified.\n");
        return -EINVAL;
    }

    extcon_data = devm_kzalloc(&pdev->dev, sizeof(struct gpio_extcon_data),
                   GFP_KERNEL);
    if (!extcon_data)
        return -ENOMEM;

    extcon_data->edev.name = pdata->name;
    extcon_data->gpio = pdata->gpio;
    extcon_data->state_on = pdata->state_on;
    extcon_data->state_off = pdata->state_off;
    if (pdata->state_on && pdata->state_off)
        extcon_data->edev.print_state = extcon_gpio_print_state;
    extcon_data->debounce_jiffies = msecs_to_jiffies(pdata->debounce);

    ret = extcon_dev_register(&extcon_data->edev, &pdev->dev);
    if (ret < 0)
        return ret;

    ret = devm_gpio_request_one(&pdev->dev, extcon_data->gpio, GPIOF_DIR_IN,
                    pdev->name);
    if (ret < 0)
        goto err;

    INIT_DELAYED_WORK(&extcon_data->work, gpio_extcon_work);

    extcon_data->irq = gpio_to_irq(extcon_data->gpio);
    if (extcon_data->irq < 0) {
        ret = extcon_data->irq;
        goto err;
    }

    ret = request_any_context_irq(extcon_data->irq, gpio_irq_handler,
                      pdata->irq_flags, pdev->name,
                      extcon_data);
    if (ret < 0)
        goto err;

    platform_set_drvdata(pdev, extcon_data);
    /* Perform initial detection */
    gpio_extcon_work(&extcon_data->work.work);

    return 0;

err:
    extcon_dev_unregister(&extcon_data->edev);

    return ret;
}

static int __devexit gpio_extcon_remove(struct platform_device *pdev)
{
    struct gpio_extcon_data *extcon_data = platform_get_drvdata(pdev);

    cancel_delayed_work_sync(&extcon_data->work);
    free_irq(extcon_data->irq, extcon_data);
    extcon_dev_unregister(&extcon_data->edev);

    return 0;
}

static struct platform_driver gpio_extcon_driver = {
    .probe      = gpio_extcon_probe,
    .remove     = __devexit_p(gpio_extcon_remove),
    .driver     = {
        .name   = "extcon-gpio",
        .owner  = THIS_MODULE,
    },
};

module_platform_driver(gpio_extcon_driver);

MODULE_AUTHOR("Mike Lockwood <[email protected]>");
MODULE_DESCRIPTION("GPIO extcon driver");
MODULE_LICENSE("GPL");