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

		kfree(list->buffer[list->tail].value);
		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]) {
		kfree(list);
		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)
			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:
	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;

	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);
		}
	}
	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;
					if (!hid->name) {
						ret = 0;
						break;
					}
					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;
					if (!hid->phys) {
						ret = 0;
						break;
					}
					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,
};

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

	list_for_each_entry(list, &dev->list, node) {
		list->buffer[list->head].value = kmemdup(data, len, GFP_ATOMIC);
		list->buffer[list->head].len = len;
		list->head = (list->head + 1) & (HIDRAW_BUFFER_SIZE - 1);
		kill_fasync(&list->fasync, SIGIO, POLL_IN);
	}

	wake_up_interruptible(&dev->wait);
}
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;

	hidraw->exist = 0;

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

	mutex_lock(&minors_lock);
	hidraw_table[hidraw->minor] = NULL;
	mutex_unlock(&minors_lock);

	if (hidraw->open) {
		hid_hw_close(hid);
		wake_up_interruptible(&hidraw->wait);
	} else {
		kfree(hidraw);
	}
}
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");
		result = 0;
		goto out;
	}

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

        cdev_init(&hidraw_cdev, &hidraw_ops);
        cdev_add(&hidraw_cdev, dev_id, HIDRAW_MAX_DEVICES);
out:
	return result;
}

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);

}