/*
   * 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) 2007-2014 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 (signal_pending(current)) {
  					ret = -ERESTARTSYS;
  					break;
  				}
  				if (!list->hidraw->exist) {
  					ret = -EIO;
  					break;
  				}
  				if (file->f_flags & O_NONBLOCK) {
  					ret = -EAGAIN;
  					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 of the report buffer 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_inode(file));
  	struct hid_device *dev;
  	__u8 *buf;
  	int ret = 0;
  
  	if (!hidraw_table[minor] || !hidraw_table[minor]->exist) {
  		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
  ",
  			 task_pid_nr(current));
  		ret = -EINVAL;
  		goto out;
  	}
  
  	if (count < 2) {
  		hid_warn(dev, "pid %d passed too short report
  ",
  			 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;
  }
  
  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_inode(file));
  	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
  ",
  				task_pid_nr(current));
  		ret = -EINVAL;
  		goto out;
  	}
  
  	if (count < 2) {
  		printk(KERN_WARNING "hidraw: pid %d passed too short report
  ",
  				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;
  	unsigned long flags;
  	int err = 0;
  
  	if (!(list = kzalloc(sizeof(struct hidraw_list), GFP_KERNEL))) {
  		err = -ENOMEM;
  		goto out;
  	}
  
  	mutex_lock(&minors_lock);
  	if (!hidraw_table[minor] || !hidraw_table[minor]->exist) {
  		err = -ENODEV;
  		goto out_unlock;
  	}
  
  	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--;
  			goto out_unlock;
  		}
  	}
  
  	list->hidraw = hidraw_table[minor];
  	mutex_init(&list->read_mutex);
  	spin_lock_irqsave(&hidraw_table[minor]->list_lock, flags);
  	list_add_tail(&list->node, &hidraw_table[minor]->list);
  	spin_unlock_irqrestore(&hidraw_table[minor]->list_lock, flags);
  	file->private_data = list;
  out_unlock:
  	mutex_unlock(&minors_lock);
  out:
  	if (err < 0)
  		kfree(list);
  	return err;
  
  }
  
  static int hidraw_fasync(int fd, struct file *file, int on)
  {
  	struct hidraw_list *list = file->private_data;
  
  	return fasync_helper(fd, file, on, &list->fasync);
  }
  
  static void drop_ref(struct hidraw *hidraw, int exists_bit)
  {
  	if (exists_bit) {
  		hidraw->exist = 0;
  		if (hidraw->open) {
  			hid_hw_close(hidraw->hid);
  			wake_up_interruptible(&hidraw->wait);
  		}
  		device_destroy(hidraw_class,
  			       MKDEV(hidraw_major, hidraw->minor));
  	} else {
  		--hidraw->open;
  	}
  	if (!hidraw->open) {
  		if (!hidraw->exist) {
  			hidraw_table[hidraw->minor] = NULL;
  			kfree(hidraw);
  		} else {
  			/* close device for last reader */
  			hid_hw_power(hidraw->hid, PM_HINT_NORMAL);
  			hid_hw_close(hidraw->hid);
  		}
  	}
  }
  
  static int hidraw_release(struct inode * inode, struct file * file)
  {
  	unsigned int minor = iminor(inode);
  	struct hidraw_list *list = file->private_data;
  	unsigned long flags;
  
  	mutex_lock(&minors_lock);
  
  	spin_lock_irqsave(&hidraw_table[minor]->list_lock, flags);
  	list_del(&list->node);
  	spin_unlock_irqrestore(&hidraw_table[minor]->list_lock, flags);
  	kfree(list);
  
  	drop_ref(hidraw_table[minor], 0);
  
  	mutex_unlock(&minors_lock);
  	return 0;
  }
  
  static long hidraw_ioctl(struct file *file, unsigned int cmd,
  							unsigned long arg)
  {
  	struct inode *inode = file_inode(file);
  	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,
  	.fasync =	hidraw_fasync,
  #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;
  	unsigned long flags;
  
  	spin_lock_irqsave(&dev->list_lock, flags);
  	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);
  	}
  	spin_unlock_irqrestore(&dev->list_lock, flags);
  
  	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, all 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;
  	}
  
  	init_waitqueue_head(&dev->wait);
  	spin_lock_init(&dev->list_lock);
  	INIT_LIST_HEAD(&dev->list);
  
  	dev->hid = hid;
  	dev->minor = minor;
  
  	dev->exist = 1;
  	hid->hidraw = dev;
  
  	mutex_unlock(&minors_lock);
  out:
  	return result;
  
  }
  EXPORT_SYMBOL_GPL(hidraw_connect);
  
  void hidraw_disconnect(struct hid_device *hid)
  {
  	struct hidraw *hidraw = hid->hidraw;
  
  	mutex_lock(&minors_lock);
  
  	drop_ref(hidraw, 1);
  
  	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
  ");
  		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;
  
  	printk(KERN_INFO "hidraw: raw HID events driver (C) Jiri Kosina
  ");
  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);
  
  }