gpio_tilt_polled.c

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/*
 *  Driver for tilt switches connected via GPIO lines
 *  not capable of generating interrupts
 *
 *  Copyright (C) 2011 Heiko Stuebner <[email protected]>
 *
 *  based on: drivers/input/keyboard/gpio_keys_polled.c
 *
 *  Copyright (C) 2007-2010 Gabor Juhos <[email protected]>
 *  Copyright (C) 2010 Nuno Goncalves <[email protected]>
 *
 *  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/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 __devinit gpio_tilt_polled_probe(struct platform_device *pdev)
{
    const struct gpio_tilt_platform_data *pdata = pdev->dev.platform_data;
    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 = &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\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 __devexit 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;

    platform_set_drvdata(pdev, NULL);

    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 = __devexit_p(gpio_tilt_polled_remove),
    .driver = {
        .name   = DRV_NAME,
        .owner  = THIS_MODULE,
    },
};

module_platform_driver(gpio_tilt_polled_driver);

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Heiko Stuebner <[email protected]>");
MODULE_DESCRIPTION("Polled GPIO tilt driver");
MODULE_ALIAS("platform:" DRV_NAME);