text: /*
   *  drivers/extcon/extcon_gpio.c
   *
   *  Single-state GPIO extcon driver based on extcon class
   *
   * Copyright (C) 2008 Google, Inc.
   * Author: Mike Lockwood <lockwood@android.com>
   *
   * Modified by MyungJoo Ham <myungjoo.ham@samsung.com> 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/extcon.h>
  #include <linux/extcon/extcon-gpio.h>
  #include <linux/gpio.h>
  #include <linux/init.h>
  #include <linux/interrupt.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/platform_device.h>
  #include <linux/slab.h>
  #include <linux/workqueue.h>
  
  struct gpio_extcon_data {
  	struct extcon_dev *edev;
  	unsigned gpio;
  	bool gpio_active_low;
  	const char *state_on;
  	const char *state_off;
  	int irq;
  	struct delayed_work work;
  	unsigned long debounce_jiffies;
  	bool check_on_resume;
  };
  
  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);
  	if (data->gpio_active_low)
  		state = !state;
  	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;
  
  	queue_delayed_work(system_power_efficient_wq, &extcon_data->work,
  			      extcon_data->debounce_jiffies);
  	return IRQ_HANDLED;
  }
  
  static ssize_t extcon_gpio_print_state(struct extcon_dev *edev, char *buf)
  {
  	struct device *dev = edev->dev.parent;
  	struct gpio_extcon_data *extcon_data = dev_get_drvdata(dev);
  	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 gpio_extcon_probe(struct platform_device *pdev)
  {
  	struct gpio_extcon_platform_data *pdata = dev_get_platdata(&pdev->dev);
  	struct gpio_extcon_data *extcon_data;
  	int ret;
  
  	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 = devm_extcon_dev_allocate(&pdev->dev, NULL);
  	if (IS_ERR(extcon_data->edev)) {
  		dev_err(&pdev->dev, "failed to allocate extcon device\n");
  		return -ENOMEM;
  	}
  
  	extcon_data->gpio = pdata->gpio;
  	extcon_data->gpio_active_low = pdata->gpio_active_low;
  	extcon_data->state_on = pdata->state_on;
  	extcon_data->state_off = pdata->state_off;
  	extcon_data->check_on_resume = pdata->check_on_resume;
  	if (pdata->state_on && pdata->state_off)
  		extcon_data->edev->print_state = extcon_gpio_print_state;
  
  	ret = devm_gpio_request_one(&pdev->dev, extcon_data->gpio, GPIOF_DIR_IN,
  				    pdev->name);
  	if (ret < 0)
  		return ret;
  
  	if (pdata->debounce) {
  		ret = gpio_set_debounce(extcon_data->gpio,
  					pdata->debounce * 1000);
  		if (ret < 0)
  			extcon_data->debounce_jiffies =
  				msecs_to_jiffies(pdata->debounce);
  	}
  
  	ret = devm_extcon_dev_register(&pdev->dev, extcon_data->edev);
  	if (ret < 0)
  		return ret;
  
  	INIT_DELAYED_WORK(&extcon_data->work, gpio_extcon_work);
  
  	extcon_data->irq = gpio_to_irq(extcon_data->gpio);
  	if (extcon_data->irq < 0)
  		return extcon_data->irq;
  
  	ret = request_any_context_irq(extcon_data->irq, gpio_irq_handler,
  				      pdata->irq_flags, pdev->name,
  				      extcon_data);
  	if (ret < 0)
  		return ret;
  
  	platform_set_drvdata(pdev, extcon_data);
  	/* Perform initial detection */
  	gpio_extcon_work(&extcon_data->work.work);
  
  	return 0;
  }
  
  static int 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);
  
  	return 0;
  }
  
  #ifdef CONFIG_PM_SLEEP
  static int gpio_extcon_resume(struct device *dev)
  {
  	struct gpio_extcon_data *extcon_data;
  
  	extcon_data = dev_get_drvdata(dev);
  	if (extcon_data->check_on_resume)
  		queue_delayed_work(system_power_efficient_wq,
  			&extcon_data->work, extcon_data->debounce_jiffies);
  
  	return 0;
  }
  #endif
  
  static SIMPLE_DEV_PM_OPS(gpio_extcon_pm_ops, NULL, gpio_extcon_resume);
  
  static struct platform_driver gpio_extcon_driver = {
  	.probe		= gpio_extcon_probe,
  	.remove		= gpio_extcon_remove,
  	.driver		= {
  		.name	= "extcon-gpio",
  		.pm	= &gpio_extcon_pm_ops,
  	},
  };
  
  module_platform_driver(gpio_extcon_driver);
  
  MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
  MODULE_DESCRIPTION("GPIO extcon driver");
  MODULE_LICENSE("GPL");
  