/*
   *  Driver for tilt switches connected via GPIO lines
   *  not capable of generating interrupts
   *
   *  Copyright (C) 2011 Heiko Stuebner <heiko@sntech.de>
   *
   *  based on: drivers/input/keyboard/gpio_keys_polled.c
   *
   *  Copyright (C) 2007-2010 Gabor Juhos <juhosg@openwrt.org>
   *  Copyright (C) 2010 Nuno Goncalves <nunojpg@gmail.com>
   *
   *  This program is free software; you can redistribute it and/or modify
   *  it under the terms of the GNU General Public License version 2 as
   *  published by the Free Software Foundation.
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/slab.h>
  #include <linux/input.h>
  #include <linux/input-polldev.h>
  #include <linux/ioport.h>
  #include <linux/platform_device.h>
  #include <linux/gpio.h>
  #include <linux/input/gpio_tilt.h>
  
  #define DRV_NAME	"gpio-tilt-polled"
  
  struct gpio_tilt_polled_dev {
  	struct input_polled_dev *poll_dev;
  	struct device *dev;
  	const struct gpio_tilt_platform_data *pdata;
  
  	int last_state;
  
  	int threshold;
  	int count;
  };
  
  static void gpio_tilt_polled_poll(struct input_polled_dev *dev)
  {
  	struct gpio_tilt_polled_dev *tdev = dev->private;
  	const struct gpio_tilt_platform_data *pdata = tdev->pdata;
  	struct input_dev *input = dev->input;
  	struct gpio_tilt_state *tilt_state = NULL;
  	int state, i;
  
  	if (tdev->count < tdev->threshold) {
  		tdev->count++;
  	} else {
  		state = 0;
  		for (i = 0; i < pdata->nr_gpios; i++)
  			state |= (!!gpio_get_value(pdata->gpios[i].gpio) << i);
  
  		if (state != tdev->last_state) {
  			for (i = 0; i < pdata->nr_states; i++)
  				if (pdata->states[i].gpios == state)
  					tilt_state = &pdata->states[i];
  
  			if (tilt_state) {
  				for (i = 0; i < pdata->nr_axes; i++)
  					input_report_abs(input,
  							 pdata->axes[i].axis,
  							 tilt_state->axes[i]);
  
  				input_sync(input);
  			}
  
  			tdev->count = 0;
  			tdev->last_state = state;
  		}
  	}
  }
  
  static void gpio_tilt_polled_open(struct input_polled_dev *dev)
  {
  	struct gpio_tilt_polled_dev *tdev = dev->private;
  	const struct gpio_tilt_platform_data *pdata = tdev->pdata;
  
  	if (pdata->enable)
  		pdata->enable(tdev->dev);
  
  	/* report initial state of the axes */
  	tdev->last_state = -1;
  	tdev->count = tdev->threshold;
  	gpio_tilt_polled_poll(tdev->poll_dev);
  }
  
  static void gpio_tilt_polled_close(struct input_polled_dev *dev)
  {
  	struct gpio_tilt_polled_dev *tdev = dev->private;
  	const struct gpio_tilt_platform_data *pdata = tdev->pdata;
  
  	if (pdata->disable)
  		pdata->disable(tdev->dev);
  }
  
  static int gpio_tilt_polled_probe(struct platform_device *pdev)
  {
  	const struct gpio_tilt_platform_data *pdata =
  			dev_get_platdata(&pdev->dev);
  	struct device *dev = &pdev->dev;
  	struct gpio_tilt_polled_dev *tdev;
  	struct input_polled_dev *poll_dev;
  	struct input_dev *input;
  	int error, i;
  
  	if (!pdata || !pdata->poll_interval)
  		return -EINVAL;
  
  	tdev = kzalloc(sizeof(struct gpio_tilt_polled_dev), GFP_KERNEL);
  	if (!tdev) {
  		dev_err(dev, "no memory for private data
  ");
  		return -ENOMEM;
  	}
  
  	error = gpio_request_array(pdata->gpios, pdata->nr_gpios);
  	if (error) {
  		dev_err(dev,
  			"Could not request tilt GPIOs: %d
  ", error);
  		goto err_free_tdev;
  	}
  
  	poll_dev = input_allocate_polled_device();
  	if (!poll_dev) {
  		dev_err(dev, "no memory for polled device
  ");
  		error = -ENOMEM;
  		goto err_free_gpios;
  	}
  
  	poll_dev->private = tdev;
  	poll_dev->poll = gpio_tilt_polled_poll;
  	poll_dev->poll_interval = pdata->poll_interval;
  	poll_dev->open = gpio_tilt_polled_open;
  	poll_dev->close = gpio_tilt_polled_close;
  
  	input = poll_dev->input;
  
  	input->name = pdev->name;
  	input->phys = DRV_NAME"/input0";
  	input->dev.parent = &pdev->dev;
  
  	input->id.bustype = BUS_HOST;
  	input->id.vendor = 0x0001;
  	input->id.product = 0x0001;
  	input->id.version = 0x0100;
  
  	__set_bit(EV_ABS, input->evbit);
  	for (i = 0; i < pdata->nr_axes; i++)
  		input_set_abs_params(input, pdata->axes[i].axis,
  				     pdata->axes[i].min, pdata->axes[i].max,
  				     pdata->axes[i].fuzz, pdata->axes[i].flat);
  
  	tdev->threshold = DIV_ROUND_UP(pdata->debounce_interval,
  				       pdata->poll_interval);
  
  	tdev->poll_dev = poll_dev;
  	tdev->dev = dev;
  	tdev->pdata = pdata;
  
  	error = input_register_polled_device(poll_dev);
  	if (error) {
  		dev_err(dev, "unable to register polled device, err=%d
  ",
  			error);
  		goto err_free_polldev;
  	}
  
  	platform_set_drvdata(pdev, tdev);
  
  	return 0;
  
  err_free_polldev:
  	input_free_polled_device(poll_dev);
  err_free_gpios:
  	gpio_free_array(pdata->gpios, pdata->nr_gpios);
  err_free_tdev:
  	kfree(tdev);
  
  	return error;
  }
  
  static int gpio_tilt_polled_remove(struct platform_device *pdev)
  {
  	struct gpio_tilt_polled_dev *tdev = platform_get_drvdata(pdev);
  	const struct gpio_tilt_platform_data *pdata = tdev->pdata;
  
  	input_unregister_polled_device(tdev->poll_dev);
  	input_free_polled_device(tdev->poll_dev);
  
  	gpio_free_array(pdata->gpios, pdata->nr_gpios);
  
  	kfree(tdev);
  
  	return 0;
  }
  
  static struct platform_driver gpio_tilt_polled_driver = {
  	.probe	= gpio_tilt_polled_probe,
  	.remove	= gpio_tilt_polled_remove,
  	.driver	= {
  		.name	= DRV_NAME,
  	},
  };
  
  module_platform_driver(gpio_tilt_polled_driver);
  
  MODULE_LICENSE("GPL v2");
  MODULE_AUTHOR("Heiko Stuebner <heiko@sntech.de>");
  MODULE_DESCRIPTION("Polled GPIO tilt driver");
  MODULE_ALIAS("platform:" DRV_NAME);