/*
 *  Driver for buttons on GPIO lines not capable of generating interrupts
 *
 *  Copyright (C) 2007-2010 Gabor Juhos <juhosg@openwrt.org>
 *  Copyright (C) 2010 Nuno Goncalves <nunojpg@gmail.com>
 *
 *  This file was based on: /drivers/input/misc/cobalt_btns.c
 *	Copyright (C) 2007 Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
 *
 *  also was based on: /drivers/input/keyboard/gpio_keys.c
 *	Copyright 2005 Phil Blundell
 *
 *  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/init.h>

#include <linux/input.h>
#include <linux/input-polldev.h>
#include <linux/ioport.h>
#include <linux/platform_device.h>

#include <linux/gpio_buttons.h>

#include <asm/gpio.h>

#define DRV_NAME	"gpio-buttons"
#define DRV_VERSION	"0.1.2"
#define PFX		DRV_NAME ": "

struct gpio_button_data {
	int last_state;
	int count;
};

struct gpio_buttons_dev {
	struct input_polled_dev *poll_dev;
	struct gpio_buttons_platform_data *pdata;
	struct gpio_button_data *data;
};

static void gpio_buttons_poll(struct input_polled_dev *dev)
{
	struct gpio_buttons_dev *bdev = dev->private;
	struct gpio_buttons_platform_data *pdata = bdev->pdata;
	struct input_dev *input = dev->input;
	int i;

	for (i = 0; i < bdev->pdata->nbuttons; i++) {
		struct gpio_button *button = &pdata->buttons[i];
		unsigned int type = button->type ?: EV_KEY;
		int state;

		if (bdev->data[i].count < button->threshold) {
			bdev->data[i].count++;
			continue;
		}

		state = gpio_get_value(button->gpio) ? 1 : 0;
		if (state != bdev->data[i].last_state) {
			input_event(input, type, button->code,
				    !!(state ^ button->active_low));
			input_sync(input);
			bdev->data[i].count = 0;
			bdev->data[i].last_state = state;
		}
	}
}

static int __devinit gpio_buttons_probe(struct platform_device *pdev)
{
	struct gpio_buttons_platform_data *pdata = pdev->dev.platform_data;
	struct gpio_buttons_dev *bdev;
	struct input_polled_dev *poll_dev;
	struct input_dev *input;
	int error, i;

	if (!pdata)
		return -ENXIO;

	bdev = kzalloc(sizeof(struct gpio_buttons_dev) +
		       sizeof(struct gpio_button_data) * pdata->nbuttons,
		       GFP_KERNEL);
	if (!bdev) {
		printk(KERN_ERR DRV_NAME "no memory for device\n");
		return -ENOMEM;
	}

	bdev->data = (struct gpio_button_data *) &bdev[1];

	poll_dev = input_allocate_polled_device();
	if (!poll_dev) {
		printk(KERN_ERR DRV_NAME "no memory for polled device\n");
		error = -ENOMEM;
		goto err_free_bdev;
	}

	poll_dev->private = bdev;
	poll_dev->poll = gpio_buttons_poll;
	poll_dev->poll_interval = pdata->poll_interval;

	input = poll_dev->input;

	input->evbit[0] = BIT(EV_KEY);
	input->name = pdev->name;
	input->phys = "gpio-buttons/input0";
	input->dev.parent = &pdev->dev;

	input->id.bustype = BUS_HOST;
	input->id.vendor = 0x0001;
	input->id.product = 0x0001;
	input->id.version = 0x0100;

	for (i = 0; i < pdata->nbuttons; i++) {
		struct gpio_button *button = &pdata->buttons[i];
		unsigned int gpio = button->gpio;
		unsigned int type = button->type ?: EV_KEY;

		error = gpio_request(gpio, button->desc ?
				button->desc : DRV_NAME);
		if (error) {
			printk(KERN_ERR PFX "unable to claim gpio %u, "
				"error %d\n", gpio, error);
			goto err_free_gpio;
		}

		error = gpio_direction_input(gpio);
		if (error) {
			printk(KERN_ERR PFX "unable to set direction on "
				"gpio %u, error %d\n", gpio, error);
			goto err_free_gpio;
		}

		input_set_capability(input, type, button->code);
		bdev->data[i].last_state = gpio_get_value(button->gpio) ? 1 : 0;
	}

	bdev->poll_dev = poll_dev;
	bdev->pdata = pdata;
	platform_set_drvdata(pdev, bdev);

	error = input_register_polled_device(poll_dev);
	if (error) {
		printk(KERN_ERR PFX "unable to register polled device, "
			"error %d\n", error);
		goto err_free_gpio;
	}

	return 0;

err_free_gpio:
	for (i = i - 1; i >= 0; i--)
		gpio_free(pdata->buttons[i].gpio);

	input_free_polled_device(poll_dev);

err_free_bdev:
	kfree(bdev);

	platform_set_drvdata(pdev, NULL);
	return error;
}

static int __devexit gpio_buttons_remove(struct platform_device *pdev)
{
	struct gpio_buttons_dev *bdev = platform_get_drvdata(pdev);
	struct gpio_buttons_platform_data *pdata = bdev->pdata;
	int i;

	input_unregister_polled_device(bdev->poll_dev);

	for (i = 0; i < pdata->nbuttons; i++)
		gpio_free(pdata->buttons[i].gpio);

	input_free_polled_device(bdev->poll_dev);

	kfree(bdev);
	platform_set_drvdata(pdev, NULL);

	return 0;
}

static struct platform_driver gpio_buttons_driver = {
	.probe	= gpio_buttons_probe,
	.remove	= __devexit_p(gpio_buttons_remove),
	.driver	= {
		.name	= DRV_NAME,
		.owner	= THIS_MODULE,
	},
};

static int __init gpio_buttons_init(void)
{
	printk(KERN_INFO DRV_NAME " driver version " DRV_VERSION "\n");
	return platform_driver_register(&gpio_buttons_driver);
}

static void __exit gpio_buttons_exit(void)
{
	platform_driver_unregister(&gpio_buttons_driver);
}

module_init(gpio_buttons_init);
module_exit(gpio_buttons_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Gabor Juhos <juhosg at openwrt.org>");
MODULE_VERSION(DRV_VERSION);
MODULE_DESCRIPTION("Polled buttons driver for CPU GPIOs");