/*
 *  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\n");
                return -ENOMEM;
        }

        error = gpio_request_array(pdata->gpios, pdata->nr_gpios);
        if (error) {
                dev_err(dev,
                        "Could not request tilt GPIOs: %d\n", error);
                goto err_free_tdev;
        }

        poll_dev = input_allocate_polled_device();
        if (!poll_dev) {
                dev_err(dev, "no memory for polled device\n");
                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 = 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\n",
                        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);