hidraw.c

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/*
 * HID raw devices, giving access to raw HID events.
 *
 * In comparison to hiddev, this device does not process the
 * hid events at all (no parsing, no lookups). This lets applications
 * to work on raw hid events as they want to, and avoids a need to
 * use a transport-specific userspace libhid/libusb libraries.
 *
 *  Copyright (c) 2007 Jiri Kosina
 */

/*
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/fs.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/cdev.h>
#include <linux/poll.h>
#include <linux/device.h>
#include <linux/major.h>
#include <linux/slab.h>
#include <linux/hid.h>
#include <linux/mutex.h>
#include <linux/sched.h>

#include <linux/hidraw.h>

static int hidraw_major;
static struct cdev hidraw_cdev;
static struct class *hidraw_class;
static struct hidraw *hidraw_table[HIDRAW_MAX_DEVICES];
static DEFINE_MUTEX(minors_lock);

static ssize_t hidraw_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos)
{
    struct hidraw_list *list = file->private_data;
    int ret = 0, len;
    DECLARE_WAITQUEUE(wait, current);

    mutex_lock(&list->read_mutex);

    while (ret == 0) {
        if (list->head == list->tail) {
            add_wait_queue(&list->hidraw->wait, &wait);
            set_current_state(TASK_INTERRUPTIBLE);

            while (list->head == list->tail) {
                if (file->f_flags & O_NONBLOCK) {
                    ret = -EAGAIN;
                    break;
                }
                if (signal_pending(current)) {
                    ret = -ERESTARTSYS;
                    break;
                }
                if (!list->hidraw->exist) {
                    ret = -EIO;
                    break;
                }

                /* allow O_NONBLOCK to work well from other threads */
                mutex_unlock(&list->read_mutex);
                schedule();
                mutex_lock(&list->read_mutex);
                set_current_state(TASK_INTERRUPTIBLE);
            }

            set_current_state(TASK_RUNNING);
            remove_wait_queue(&list->hidraw->wait, &wait);
        }

        if (ret)
            goto out;

        len = list->buffer[list->tail].len > count ?
            count : list->buffer[list->tail].len;

        if (list->buffer[list->tail].value) {
            if (copy_to_user(buffer, list->buffer[list->tail].value, len)) {
                ret = -EFAULT;
                goto out;
            }
            ret = len;
        }

        kfree(list->buffer[list->tail].value);
        list->buffer[list->tail].value = NULL;
        list->tail = (list->tail + 1) & (HIDRAW_BUFFER_SIZE - 1);
    }
out:
    mutex_unlock(&list->read_mutex);
    return ret;
}

/* The first byte is expected to be a report number.
 * This function is to be called with the minors_lock mutex held */
static ssize_t hidraw_send_report(struct file *file, const char __user *buffer, size_t count, unsigned char report_type)
{
    unsigned int minor = iminor(file->f_path.dentry->d_inode);
    struct hid_device *dev;
    __u8 *buf;
    int ret = 0;

    if (!hidraw_table[minor]) {
        ret = -ENODEV;
        goto out;
    }

    dev = hidraw_table[minor]->hid;

    if (!dev->hid_output_raw_report) {
        ret = -ENODEV;
        goto out;
    }

    if (count > HID_MAX_BUFFER_SIZE) {
        hid_warn(dev, "pid %d passed too large report\n",
             task_pid_nr(current));
        ret = -EINVAL;
        goto out;
    }

    if (count < 2) {
        hid_warn(dev, "pid %d passed too short report\n",
             task_pid_nr(current));
        ret = -EINVAL;
        goto out;
    }

    buf = kmalloc(count * sizeof(__u8), GFP_KERNEL);
    if (!buf) {
        ret = -ENOMEM;
        goto out;
    }

    if (copy_from_user(buf, buffer, count)) {
        ret = -EFAULT;
        goto out_free;
    }

    ret = dev->hid_output_raw_report(dev, buf, count, report_type);
out_free:
    kfree(buf);
out:
    return ret;
}

/* the first byte is expected to be a report number */
static ssize_t hidraw_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
{
    ssize_t ret;
    mutex_lock(&minors_lock);
    ret = hidraw_send_report(file, buffer, count, HID_OUTPUT_REPORT);
    mutex_unlock(&minors_lock);
    return ret;
}


/* This function performs a Get_Report transfer over the control endpoint
 * per section 7.2.1 of the HID specification, version 1.1.  The first byte
 * of buffer is the report number to request, or 0x0 if the defice does not
 * use numbered reports. The report_type parameter can be HID_FEATURE_REPORT
 * or HID_INPUT_REPORT.  This function is to be called with the minors_lock
 *  mutex held. */
static ssize_t hidraw_get_report(struct file *file, char __user *buffer, size_t count, unsigned char report_type)
{
    unsigned int minor = iminor(file->f_path.dentry->d_inode);
    struct hid_device *dev;
    __u8 *buf;
    int ret = 0, len;
    unsigned char report_number;

    dev = hidraw_table[minor]->hid;

    if (!dev->hid_get_raw_report) {
        ret = -ENODEV;
        goto out;
    }

    if (count > HID_MAX_BUFFER_SIZE) {
        printk(KERN_WARNING "hidraw: pid %d passed too large report\n",
                task_pid_nr(current));
        ret = -EINVAL;
        goto out;
    }

    if (count < 2) {
        printk(KERN_WARNING "hidraw: pid %d passed too short report\n",
                task_pid_nr(current));
        ret = -EINVAL;
        goto out;
    }

    buf = kmalloc(count * sizeof(__u8), GFP_KERNEL);
    if (!buf) {
        ret = -ENOMEM;
        goto out;
    }

    /* Read the first byte from the user. This is the report number,
     * which is passed to dev->hid_get_raw_report(). */
    if (copy_from_user(&report_number, buffer, 1)) {
        ret = -EFAULT;
        goto out_free;
    }

    ret = dev->hid_get_raw_report(dev, report_number, buf, count, report_type);

    if (ret < 0)
        goto out_free;

    len = (ret < count) ? ret : count;

    if (copy_to_user(buffer, buf, len)) {
        ret = -EFAULT;
        goto out_free;
    }

    ret = len;

out_free:
    kfree(buf);
out:
    return ret;
}

static unsigned int hidraw_poll(struct file *file, poll_table *wait)
{
    struct hidraw_list *list = file->private_data;

    poll_wait(file, &list->hidraw->wait, wait);
    if (list->head != list->tail)
        return POLLIN | POLLRDNORM;
    if (!list->hidraw->exist)
        return POLLERR | POLLHUP;
    return 0;
}

static int hidraw_open(struct inode *inode, struct file *file)
{
    unsigned int minor = iminor(inode);
    struct hidraw *dev;
    struct hidraw_list *list;
    int err = 0;

    if (!(list = kzalloc(sizeof(struct hidraw_list), GFP_KERNEL))) {
        err = -ENOMEM;
        goto out;
    }

    mutex_lock(&minors_lock);
    if (!hidraw_table[minor]) {
        err = -ENODEV;
        goto out_unlock;
    }

    list->hidraw = hidraw_table[minor];
    mutex_init(&list->read_mutex);
    list_add_tail(&list->node, &hidraw_table[minor]->list);
    file->private_data = list;

    dev = hidraw_table[minor];
    if (!dev->open++) {
        err = hid_hw_power(dev->hid, PM_HINT_FULLON);
        if (err < 0) {
            dev->open--;
            goto out_unlock;
        }

        err = hid_hw_open(dev->hid);
        if (err < 0) {
            hid_hw_power(dev->hid, PM_HINT_NORMAL);
            dev->open--;
        }
    }

out_unlock:
    mutex_unlock(&minors_lock);
out:
    if (err < 0)
        kfree(list);
    return err;

}

static int hidraw_release(struct inode * inode, struct file * file)
{
    unsigned int minor = iminor(inode);
    struct hidraw *dev;
    struct hidraw_list *list = file->private_data;
    int ret;
    int i;

    mutex_lock(&minors_lock);
    if (!hidraw_table[minor]) {
        ret = -ENODEV;
        goto unlock;
    }

    list_del(&list->node);
    dev = hidraw_table[minor];
    if (!--dev->open) {
        if (list->hidraw->exist) {
            hid_hw_power(dev->hid, PM_HINT_NORMAL);
            hid_hw_close(dev->hid);
        } else {
            kfree(list->hidraw);
        }
    }

    for (i = 0; i < HIDRAW_BUFFER_SIZE; ++i)
        kfree(list->buffer[i].value);
    kfree(list);
    ret = 0;
unlock:
    mutex_unlock(&minors_lock);

    return ret;
}

static long hidraw_ioctl(struct file *file, unsigned int cmd,
                            unsigned long arg)
{
    struct inode *inode = file->f_path.dentry->d_inode;
    unsigned int minor = iminor(inode);
    long ret = 0;
    struct hidraw *dev;
    void __user *user_arg = (void __user*) arg;

    mutex_lock(&minors_lock);
    dev = hidraw_table[minor];
    if (!dev) {
        ret = -ENODEV;
        goto out;
    }

    switch (cmd) {
        case HIDIOCGRDESCSIZE:
            if (put_user(dev->hid->rsize, (int __user *)arg))
                ret = -EFAULT;
            break;

        case HIDIOCGRDESC:
            {
                __u32 len;

                if (get_user(len, (int __user *)arg))
                    ret = -EFAULT;
                else if (len > HID_MAX_DESCRIPTOR_SIZE - 1)
                    ret = -EINVAL;
                else if (copy_to_user(user_arg + offsetof(
                    struct hidraw_report_descriptor,
                    value[0]),
                    dev->hid->rdesc,
                    min(dev->hid->rsize, len)))
                    ret = -EFAULT;
                break;
            }
        case HIDIOCGRAWINFO:
            {
                struct hidraw_devinfo dinfo;

                dinfo.bustype = dev->hid->bus;
                dinfo.vendor = dev->hid->vendor;
                dinfo.product = dev->hid->product;
                if (copy_to_user(user_arg, &dinfo, sizeof(dinfo)))
                    ret = -EFAULT;
                break;
            }
        default:
            {
                struct hid_device *hid = dev->hid;
                if (_IOC_TYPE(cmd) != 'H') {
                    ret = -EINVAL;
                    break;
                }

                if (_IOC_NR(cmd) == _IOC_NR(HIDIOCSFEATURE(0))) {
                    int len = _IOC_SIZE(cmd);
                    ret = hidraw_send_report(file, user_arg, len, HID_FEATURE_REPORT);
                    break;
                }
                if (_IOC_NR(cmd) == _IOC_NR(HIDIOCGFEATURE(0))) {
                    int len = _IOC_SIZE(cmd);
                    ret = hidraw_get_report(file, user_arg, len, HID_FEATURE_REPORT);
                    break;
                }

                /* Begin Read-only ioctls. */
                if (_IOC_DIR(cmd) != _IOC_READ) {
                    ret = -EINVAL;
                    break;
                }

                if (_IOC_NR(cmd) == _IOC_NR(HIDIOCGRAWNAME(0))) {
                    int len = strlen(hid->name) + 1;
                    if (len > _IOC_SIZE(cmd))
                        len = _IOC_SIZE(cmd);
                    ret = copy_to_user(user_arg, hid->name, len) ?
                        -EFAULT : len;
                    break;
                }

                if (_IOC_NR(cmd) == _IOC_NR(HIDIOCGRAWPHYS(0))) {
                    int len = strlen(hid->phys) + 1;
                    if (len > _IOC_SIZE(cmd))
                        len = _IOC_SIZE(cmd);
                    ret = copy_to_user(user_arg, hid->phys, len) ?
                        -EFAULT : len;
                    break;
                }
            }

        ret = -ENOTTY;
    }
out:
    mutex_unlock(&minors_lock);
    return ret;
}

static const struct file_operations hidraw_ops = {
    .owner =        THIS_MODULE,
    .read =         hidraw_read,
    .write =        hidraw_write,
    .poll =         hidraw_poll,
    .open =         hidraw_open,
    .release =      hidraw_release,
    .unlocked_ioctl = hidraw_ioctl,
#ifdef CONFIG_COMPAT
    .compat_ioctl   = hidraw_ioctl,
#endif
    .llseek =   noop_llseek,
};

int hidraw_report_event(struct hid_device *hid, u8 *data, int len)
{
    struct hidraw *dev = hid->hidraw;
    struct hidraw_list *list;
    int ret = 0;

    list_for_each_entry(list, &dev->list, node) {
        int new_head = (list->head + 1) & (HIDRAW_BUFFER_SIZE - 1);

        if (new_head == list->tail)
            continue;

        if (!(list->buffer[list->head].value = kmemdup(data, len, GFP_ATOMIC))) {
            ret = -ENOMEM;
            break;
        }
        list->buffer[list->head].len = len;
        list->head = new_head;
        kill_fasync(&list->fasync, SIGIO, POLL_IN);
    }

    wake_up_interruptible(&dev->wait);
    return ret;
}
EXPORT_SYMBOL_GPL(hidraw_report_event);

int hidraw_connect(struct hid_device *hid)
{
    int minor, result;
    struct hidraw *dev;

    /* we accept any HID device, no matter the applications */

    dev = kzalloc(sizeof(struct hidraw), GFP_KERNEL);
    if (!dev)
        return -ENOMEM;

    result = -EINVAL;

    mutex_lock(&minors_lock);

    for (minor = 0; minor < HIDRAW_MAX_DEVICES; minor++) {
        if (hidraw_table[minor])
            continue;
        hidraw_table[minor] = dev;
        result = 0;
        break;
    }

    if (result) {
        mutex_unlock(&minors_lock);
        kfree(dev);
        goto out;
    }

    dev->dev = device_create(hidraw_class, &hid->dev, MKDEV(hidraw_major, minor),
                 NULL, "%s%d", "hidraw", minor);

    if (IS_ERR(dev->dev)) {
        hidraw_table[minor] = NULL;
        mutex_unlock(&minors_lock);
        result = PTR_ERR(dev->dev);
        kfree(dev);
        goto out;
    }

    mutex_unlock(&minors_lock);
    init_waitqueue_head(&dev->wait);
    INIT_LIST_HEAD(&dev->list);

    dev->hid = hid;
    dev->minor = minor;

    dev->exist = 1;
    hid->hidraw = dev;

out:
    return result;

}
EXPORT_SYMBOL_GPL(hidraw_connect);

void hidraw_disconnect(struct hid_device *hid)
{
    struct hidraw *hidraw = hid->hidraw;

    mutex_lock(&minors_lock);
    hidraw->exist = 0;

    device_destroy(hidraw_class, MKDEV(hidraw_major, hidraw->minor));

    hidraw_table[hidraw->minor] = NULL;

    if (hidraw->open) {
        hid_hw_close(hid);
        wake_up_interruptible(&hidraw->wait);
    } else {
        kfree(hidraw);
    }
    mutex_unlock(&minors_lock);
}
EXPORT_SYMBOL_GPL(hidraw_disconnect);

int __init hidraw_init(void)
{
    int result;
    dev_t dev_id;

    result = alloc_chrdev_region(&dev_id, HIDRAW_FIRST_MINOR,
            HIDRAW_MAX_DEVICES, "hidraw");

    hidraw_major = MAJOR(dev_id);

    if (result < 0) {
        pr_warn("can't get major number\n");
        goto out;
    }

    hidraw_class = class_create(THIS_MODULE, "hidraw");
    if (IS_ERR(hidraw_class)) {
        result = PTR_ERR(hidraw_class);
        goto error_cdev;
    }

        cdev_init(&hidraw_cdev, &hidraw_ops);
    result = cdev_add(&hidraw_cdev, dev_id, HIDRAW_MAX_DEVICES);
    if (result < 0)
        goto error_class;

out:
    return result;

error_class:
    class_destroy(hidraw_class);
error_cdev:
    unregister_chrdev_region(dev_id, HIDRAW_MAX_DEVICES);
    goto out;
}

void hidraw_exit(void)
{
    dev_t dev_id = MKDEV(hidraw_major, 0);

    cdev_del(&hidraw_cdev);
    class_destroy(hidraw_class);
    unregister_chrdev_region(dev_id, HIDRAW_MAX_DEVICES);

}