timed_gpio.c

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/* drivers/misc/timed_gpio.c
 *
 * Copyright (C) 2008 Google, Inc.
 * Author: Mike Lockwood <[email protected]>
 *
 * 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/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/hrtimer.h>
#include <linux/err.h>
#include <linux/gpio.h>

#include "timed_output.h"
#include "timed_gpio.h"


struct timed_gpio_data {
    struct timed_output_dev dev;
    struct hrtimer timer;
    spinlock_t lock;
    unsigned gpio;
    int max_timeout;
    u8 active_low;
};

static enum hrtimer_restart gpio_timer_func(struct hrtimer *timer)
{
    struct timed_gpio_data *data =
        container_of(timer, struct timed_gpio_data, timer);

    gpio_direction_output(data->gpio, data->active_low ? 1 : 0);
    return HRTIMER_NORESTART;
}

static int gpio_get_time(struct timed_output_dev *dev)
{
    struct timed_gpio_data  *data =
        container_of(dev, struct timed_gpio_data, dev);

    if (hrtimer_active(&data->timer)) {
        ktime_t r = hrtimer_get_remaining(&data->timer);
        struct timeval t = ktime_to_timeval(r);
        return t.tv_sec * 1000 + t.tv_usec / 1000;
    } else
        return 0;
}

static void gpio_enable(struct timed_output_dev *dev, int value)
{
    struct timed_gpio_data  *data =
        container_of(dev, struct timed_gpio_data, dev);
    unsigned long   flags;

    spin_lock_irqsave(&data->lock, flags);

    /* cancel previous timer and set GPIO according to value */
    hrtimer_cancel(&data->timer);
    gpio_direction_output(data->gpio, data->active_low ? !value : !!value);

    if (value > 0) {
        if (value > data->max_timeout)
            value = data->max_timeout;

        hrtimer_start(&data->timer,
            ktime_set(value / 1000, (value % 1000) * 1000000),
            HRTIMER_MODE_REL);
    }

    spin_unlock_irqrestore(&data->lock, flags);
}

static int timed_gpio_probe(struct platform_device *pdev)
{
    struct timed_gpio_platform_data *pdata = pdev->dev.platform_data;
    struct timed_gpio *cur_gpio;
    struct timed_gpio_data *gpio_data, *gpio_dat;
    int i, ret;

    if (!pdata)
        return -EBUSY;

    gpio_data = kzalloc(sizeof(struct timed_gpio_data) * pdata->num_gpios,
            GFP_KERNEL);
    if (!gpio_data)
        return -ENOMEM;

    for (i = 0; i < pdata->num_gpios; i++) {
        cur_gpio = &pdata->gpios[i];
        gpio_dat = &gpio_data[i];

        hrtimer_init(&gpio_dat->timer, CLOCK_MONOTONIC,
                HRTIMER_MODE_REL);
        gpio_dat->timer.function = gpio_timer_func;
        spin_lock_init(&gpio_dat->lock);

        gpio_dat->dev.name = cur_gpio->name;
        gpio_dat->dev.get_time = gpio_get_time;
        gpio_dat->dev.enable = gpio_enable;
        ret = gpio_request(cur_gpio->gpio, cur_gpio->name);
        if (ret < 0)
            goto err_out;
        ret = timed_output_dev_register(&gpio_dat->dev);
        if (ret < 0) {
            gpio_free(cur_gpio->gpio);
            goto err_out;
        }

        gpio_dat->gpio = cur_gpio->gpio;
        gpio_dat->max_timeout = cur_gpio->max_timeout;
        gpio_dat->active_low = cur_gpio->active_low;
        gpio_direction_output(gpio_dat->gpio, gpio_dat->active_low);
    }

    platform_set_drvdata(pdev, gpio_data);

    return 0;

err_out:
    while (--i >= 0) {
        timed_output_dev_unregister(&gpio_data[i].dev);
        gpio_free(gpio_data[i].gpio);
    }
    kfree(gpio_data);

    return ret;
}

static int timed_gpio_remove(struct platform_device *pdev)
{
    struct timed_gpio_platform_data *pdata = pdev->dev.platform_data;
    struct timed_gpio_data *gpio_data = platform_get_drvdata(pdev);
    int i;

    for (i = 0; i < pdata->num_gpios; i++) {
        timed_output_dev_unregister(&gpio_data[i].dev);
        gpio_free(gpio_data[i].gpio);
    }

    kfree(gpio_data);

    return 0;
}

static struct platform_driver timed_gpio_driver = {
    .probe      = timed_gpio_probe,
    .remove     = timed_gpio_remove,
    .driver     = {
        .name       = TIMED_GPIO_NAME,
        .owner      = THIS_MODULE,
    },
};

module_platform_driver(timed_gpio_driver);

MODULE_AUTHOR("Mike Lockwood <[email protected]>");
MODULE_DESCRIPTION("timed gpio driver");
MODULE_LICENSE("GPL");