linux-imx

/*

 * Userspace driver for the LED subsystem

 *

 * Copyright (C) 2016 David Lechner <david@lechnology.com>

 *

 * Based on uinput.c: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * 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/fs.h>

#include <linux/init.h>

#include <linux/leds.h>

#include <linux/miscdevice.h>

#include <linux/module.h>

#include <linux/poll.h>

#include <linux/sched.h>

#include <linux/slab.h>

​

#include <uapi/linux/uleds.h>

​

#define ULEDS_NAME  "uleds"

​

enum uleds_state {

    ULEDS_STATE_UNKNOWN,

    ULEDS_STATE_REGISTERED,

};

​

struct uleds_device {

    struct uleds_user_dev   user_dev;

    struct led_classdev led_cdev;

    struct mutex        mutex;

    enum uleds_state    state;

    wait_queue_head_t   waitq;

    int         brightness;

    bool            new_data;

};

​

static struct miscdevice uleds_misc;

​

static void uleds_brightness_set(struct led_classdev *led_cdev,

                 enum led_brightness brightness)

{

    struct uleds_device *udev = container_of(led_cdev, struct uleds_device,

                         led_cdev);

​

    if (udev->brightness != brightness) {

        udev->brightness = brightness;

        udev->new_data = true;

        wake_up_interruptible(&udev->waitq);

    }

}

​

static int uleds_open(struct inode *inode, struct file *file)

{

    struct uleds_device *udev;

​

    udev = kzalloc(sizeof(*udev), GFP_KERNEL);

    if (!udev)

        return -ENOMEM;

​

    udev->led_cdev.name = udev->user_dev.name;

    udev->led_cdev.brightness_set = uleds_brightness_set;

​

    mutex_init(&udev->mutex);

    init_waitqueue_head(&udev->waitq);

    udev->state = ULEDS_STATE_UNKNOWN;

​

    file->private_data = udev;

    nonseekable_open(inode, file);

​

    return 0;

}

​

static ssize_t uleds_write(struct file *file, const char __user *buffer,

               size_t count, loff_t *ppos)

{

    struct uleds_device *udev = file->private_data;

    const char *name;

    int ret;

​

    if (count == 0)

        return 0;

​

    ret = mutex_lock_interruptible(&udev->mutex);