/*
   * drivers/uio/uio.c
   *
   * Copyright(C) 2005, Benedikt Spranger <b.spranger@linutronix.de>
   * Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
   * Copyright(C) 2006, Hans J. Koch <hjk@linutronix.de>
   * Copyright(C) 2006, Greg Kroah-Hartman <greg@kroah.com>
   *
   * Userspace IO
   *
   * Base Functions
   *
   * Licensed under the GPLv2 only.
   */
  
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/poll.h>
  #include <linux/device.h>

  #include <linux/slab.h>

  #include <linux/mm.h>
  #include <linux/idr.h>

  #include <linux/sched.h>

  #include <linux/string.h>
  #include <linux/kobject.h>
  #include <linux/uio_driver.h>
  
  #define UIO_MAX_DEVICES 255
  
  struct uio_device {
  	struct module		*owner;
  	struct device		*dev;
  	int			minor;
  	atomic_t		event;
  	struct fasync_struct	*async_queue;
  	wait_queue_head_t	wait;
  	int			vma_count;
  	struct uio_info		*info;

  	struct kobject		*map_dir;

  	struct kobject		*portio_dir;

  };
  
  static int uio_major;
  static DEFINE_IDR(uio_idr);

  static const struct file_operations uio_fops;

  
  /* UIO class infrastructure */
  static struct uio_class {
  	struct kref kref;
  	struct class *class;
  } *uio_class;

  /* Protect idr accesses */
  static DEFINE_MUTEX(minor_lock);

  /*
   * attributes
   */

  struct uio_map {
  	struct kobject kobj;
  	struct uio_mem *mem;

  };

  #define to_map(map) container_of(map, struct uio_map, kobj)

  static ssize_t map_name_show(struct uio_mem *mem, char *buf)
  {
  	if (unlikely(!mem->name))
  		mem->name = "";
  
  	return sprintf(buf, "%s
  ", mem->name);
  }

  static ssize_t map_addr_show(struct uio_mem *mem, char *buf)

  {

  	return sprintf(buf, "0x%lx
  ", mem->addr);
  }

  static ssize_t map_size_show(struct uio_mem *mem, char *buf)
  {
  	return sprintf(buf, "0x%lx
  ", mem->size);

  }

  static ssize_t map_offset_show(struct uio_mem *mem, char *buf)
  {
  	return sprintf(buf, "0x%lx
  ", mem->addr & ~PAGE_MASK);
  }

  struct map_sysfs_entry {

  	struct attribute attr;
  	ssize_t (*show)(struct uio_mem *, char *);
  	ssize_t (*store)(struct uio_mem *, const char *, size_t);
  };

  static struct map_sysfs_entry name_attribute =
  	__ATTR(name, S_IRUGO, map_name_show, NULL);

  static struct map_sysfs_entry addr_attribute =

  	__ATTR(addr, S_IRUGO, map_addr_show, NULL);

  static struct map_sysfs_entry size_attribute =

  	__ATTR(size, S_IRUGO, map_size_show, NULL);

  static struct map_sysfs_entry offset_attribute =

  	__ATTR(offset, S_IRUGO, map_offset_show, NULL);

  static struct attribute *attrs[] = {

  	&name_attribute.attr,

  	&addr_attribute.attr,

  	&size_attribute.attr,

  	&offset_attribute.attr,

  	NULL,	/* need to NULL terminate the list of attributes */

  };

  static void map_release(struct kobject *kobj)
  {
  	struct uio_map *map = to_map(kobj);
  	kfree(map);
  }

  static ssize_t map_type_show(struct kobject *kobj, struct attribute *attr,
  			     char *buf)
  {
  	struct uio_map *map = to_map(kobj);
  	struct uio_mem *mem = map->mem;

  	struct map_sysfs_entry *entry;

  	entry = container_of(attr, struct map_sysfs_entry, attr);

  
  	if (!entry->show)
  		return -EIO;
  
  	return entry->show(mem, buf);
  }

  static const struct sysfs_ops map_sysfs_ops = {

  	.show = map_type_show,
  };

  static struct kobj_type map_attr_type = {

  	.release	= map_release,

  	.sysfs_ops	= &map_sysfs_ops,

  	.default_attrs	= attrs,

  };

  struct uio_portio {
  	struct kobject kobj;
  	struct uio_port *port;
  };
  #define to_portio(portio) container_of(portio, struct uio_portio, kobj)

  static ssize_t portio_name_show(struct uio_port *port, char *buf)
  {
  	if (unlikely(!port->name))
  		port->name = "";
  
  	return sprintf(buf, "%s
  ", port->name);
  }

  static ssize_t portio_start_show(struct uio_port *port, char *buf)
  {
  	return sprintf(buf, "0x%lx
  ", port->start);
  }
  
  static ssize_t portio_size_show(struct uio_port *port, char *buf)
  {
  	return sprintf(buf, "0x%lx
  ", port->size);
  }
  
  static ssize_t portio_porttype_show(struct uio_port *port, char *buf)
  {
  	const char *porttypes[] = {"none", "x86", "gpio", "other"};
  
  	if ((port->porttype < 0) || (port->porttype > UIO_PORT_OTHER))
  		return -EINVAL;
  
  	return sprintf(buf, "port_%s
  ", porttypes[port->porttype]);
  }
  
  struct portio_sysfs_entry {
  	struct attribute attr;
  	ssize_t (*show)(struct uio_port *, char *);
  	ssize_t (*store)(struct uio_port *, const char *, size_t);
  };

  static struct portio_sysfs_entry portio_name_attribute =
  	__ATTR(name, S_IRUGO, portio_name_show, NULL);

  static struct portio_sysfs_entry portio_start_attribute =
  	__ATTR(start, S_IRUGO, portio_start_show, NULL);
  static struct portio_sysfs_entry portio_size_attribute =
  	__ATTR(size, S_IRUGO, portio_size_show, NULL);
  static struct portio_sysfs_entry portio_porttype_attribute =
  	__ATTR(porttype, S_IRUGO, portio_porttype_show, NULL);
  
  static struct attribute *portio_attrs[] = {

  	&portio_name_attribute.attr,

  	&portio_start_attribute.attr,
  	&portio_size_attribute.attr,
  	&portio_porttype_attribute.attr,
  	NULL,
  };
  
  static void portio_release(struct kobject *kobj)
  {
  	struct uio_portio *portio = to_portio(kobj);
  	kfree(portio);
  }
  
  static ssize_t portio_type_show(struct kobject *kobj, struct attribute *attr,
  			     char *buf)
  {
  	struct uio_portio *portio = to_portio(kobj);
  	struct uio_port *port = portio->port;
  	struct portio_sysfs_entry *entry;
  
  	entry = container_of(attr, struct portio_sysfs_entry, attr);
  
  	if (!entry->show)
  		return -EIO;
  
  	return entry->show(port, buf);
  }

  static const struct sysfs_ops portio_sysfs_ops = {

  	.show = portio_type_show,
  };
  
  static struct kobj_type portio_attr_type = {
  	.release	= portio_release,
  	.sysfs_ops	= &portio_sysfs_ops,
  	.default_attrs	= portio_attrs,
  };

  static ssize_t show_name(struct device *dev,
  			 struct device_attribute *attr, char *buf)
  {
  	struct uio_device *idev = dev_get_drvdata(dev);
  	if (idev)
  		return sprintf(buf, "%s
  ", idev->info->name);
  	else
  		return -ENODEV;
  }
  static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
  
  static ssize_t show_version(struct device *dev,
  			    struct device_attribute *attr, char *buf)
  {
  	struct uio_device *idev = dev_get_drvdata(dev);
  	if (idev)
  		return sprintf(buf, "%s
  ", idev->info->version);
  	else
  		return -ENODEV;
  }
  static DEVICE_ATTR(version, S_IRUGO, show_version, NULL);
  
  static ssize_t show_event(struct device *dev,
  			  struct device_attribute *attr, char *buf)
  {
  	struct uio_device *idev = dev_get_drvdata(dev);
  	if (idev)
  		return sprintf(buf, "%u
  ",
  				(unsigned int)atomic_read(&idev->event));
  	else
  		return -ENODEV;
  }
  static DEVICE_ATTR(event, S_IRUGO, show_event, NULL);
  
  static struct attribute *uio_attrs[] = {
  	&dev_attr_name.attr,
  	&dev_attr_version.attr,
  	&dev_attr_event.attr,
  	NULL,
  };
  
  static struct attribute_group uio_attr_grp = {
  	.attrs = uio_attrs,
  };
  
  /*
   * device functions
   */
  static int uio_dev_add_attributes(struct uio_device *idev)
  {
  	int ret;

  	int mi, pi;

  	int map_found = 0;

  	int portio_found = 0;

  	struct uio_mem *mem;

  	struct uio_map *map;

  	struct uio_port *port;
  	struct uio_portio *portio;

  
  	ret = sysfs_create_group(&idev->dev->kobj, &uio_attr_grp);
  	if (ret)
  		goto err_group;
  
  	for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
  		mem = &idev->info->mem[mi];
  		if (mem->size == 0)
  			break;
  		if (!map_found) {
  			map_found = 1;

  			idev->map_dir = kobject_create_and_add("maps",
  							&idev->dev->kobj);
  			if (!idev->map_dir)

  				goto err_map;

  		}

  		map = kzalloc(sizeof(*map), GFP_KERNEL);
  		if (!map)

  			goto err_map;

  		kobject_init(&map->kobj, &map_attr_type);

  		map->mem = mem;
  		mem->map = map;

  		ret = kobject_add(&map->kobj, idev->map_dir, "map%d", mi);

  		if (ret)

  			goto err_map;

  		ret = kobject_uevent(&map->kobj, KOBJ_ADD);

  		if (ret)

  			goto err_map;
  	}
  
  	for (pi = 0; pi < MAX_UIO_PORT_REGIONS; pi++) {
  		port = &idev->info->port[pi];
  		if (port->size == 0)
  			break;
  		if (!portio_found) {
  			portio_found = 1;
  			idev->portio_dir = kobject_create_and_add("portio",
  							&idev->dev->kobj);
  			if (!idev->portio_dir)
  				goto err_portio;
  		}
  		portio = kzalloc(sizeof(*portio), GFP_KERNEL);
  		if (!portio)
  			goto err_portio;
  		kobject_init(&portio->kobj, &portio_attr_type);
  		portio->port = port;
  		port->portio = portio;
  		ret = kobject_add(&portio->kobj, idev->portio_dir,
  							"port%d", pi);
  		if (ret)
  			goto err_portio;
  		ret = kobject_uevent(&portio->kobj, KOBJ_ADD);
  		if (ret)
  			goto err_portio;

  	}
  
  	return 0;

  err_portio:
  	for (pi--; pi >= 0; pi--) {
  		port = &idev->info->port[pi];
  		portio = port->portio;
  		kobject_put(&portio->kobj);
  	}
  	kobject_put(idev->portio_dir);
  err_map:

  	for (mi--; mi>=0; mi--) {
  		mem = &idev->info->mem[mi];

  		map = mem->map;

  		kobject_put(&map->kobj);

  	}

  	kobject_put(idev->map_dir);

  	sysfs_remove_group(&idev->dev->kobj, &uio_attr_grp);
  err_group:
  	dev_err(idev->dev, "error creating sysfs files (%d)
  ", ret);
  	return ret;
  }
  
  static void uio_dev_del_attributes(struct uio_device *idev)
  {

  	int i;

  	struct uio_mem *mem;

  	struct uio_port *port;
  
  	for (i = 0; i < MAX_UIO_MAPS; i++) {
  		mem = &idev->info->mem[i];

  		if (mem->size == 0)
  			break;

  		kobject_put(&mem->map->kobj);

  	}

  	kobject_put(idev->map_dir);

  
  	for (i = 0; i < MAX_UIO_PORT_REGIONS; i++) {
  		port = &idev->info->port[i];
  		if (port->size == 0)
  			break;
  		kobject_put(&port->portio->kobj);
  	}
  	kobject_put(idev->portio_dir);

  	sysfs_remove_group(&idev->dev->kobj, &uio_attr_grp);
  }
  
  static int uio_get_minor(struct uio_device *idev)
  {

  	int retval = -ENOMEM;
  	int id;
  
  	mutex_lock(&minor_lock);
  	if (idr_pre_get(&uio_idr, GFP_KERNEL) == 0)
  		goto exit;
  
  	retval = idr_get_new(&uio_idr, idev, &id);
  	if (retval < 0) {
  		if (retval == -EAGAIN)
  			retval = -ENOMEM;
  		goto exit;
  	}
  	idev->minor = id & MAX_ID_MASK;
  exit:
  	mutex_unlock(&minor_lock);
  	return retval;
  }
  
  static void uio_free_minor(struct uio_device *idev)
  {

  	mutex_lock(&minor_lock);

  	idr_remove(&uio_idr, idev->minor);

  	mutex_unlock(&minor_lock);

  }
  
  /**
   * uio_event_notify - trigger an interrupt event
   * @info: UIO device capabilities
   */
  void uio_event_notify(struct uio_info *info)
  {
  	struct uio_device *idev = info->uio_dev;
  
  	atomic_inc(&idev->event);
  	wake_up_interruptible(&idev->wait);
  	kill_fasync(&idev->async_queue, SIGIO, POLL_IN);
  }
  EXPORT_SYMBOL_GPL(uio_event_notify);
  
  /**
   * uio_interrupt - hardware interrupt handler
   * @irq: IRQ number, can be UIO_IRQ_CYCLIC for cyclic timer
   * @dev_id: Pointer to the devices uio_device structure
   */
  static irqreturn_t uio_interrupt(int irq, void *dev_id)
  {
  	struct uio_device *idev = (struct uio_device *)dev_id;
  	irqreturn_t ret = idev->info->handler(irq, idev->info);
  
  	if (ret == IRQ_HANDLED)
  		uio_event_notify(idev->info);
  
  	return ret;
  }
  
  struct uio_listener {
  	struct uio_device *dev;
  	s32 event_count;
  };
  
  static int uio_open(struct inode *inode, struct file *filep)
  {
  	struct uio_device *idev;
  	struct uio_listener *listener;
  	int ret = 0;

  	mutex_lock(&minor_lock);

  	idev = idr_find(&uio_idr, iminor(inode));

  	mutex_unlock(&minor_lock);

  	if (!idev) {
  		ret = -ENODEV;
  		goto out;
  	}

  	if (!try_module_get(idev->owner)) {
  		ret = -ENODEV;
  		goto out;
  	}

  	listener = kmalloc(sizeof(*listener), GFP_KERNEL);

  	if (!listener) {
  		ret = -ENOMEM;
  		goto err_alloc_listener;
  	}

  
  	listener->dev = idev;
  	listener->event_count = atomic_read(&idev->event);
  	filep->private_data = listener;
  
  	if (idev->info->open) {

  		ret = idev->info->open(idev->info, inode);

  		if (ret)
  			goto err_infoopen;

  	}

  	return 0;
  
  err_infoopen:

  	kfree(listener);

  err_alloc_listener:

  	module_put(idev->owner);

  out:

  	return ret;
  }
  
  static int uio_fasync(int fd, struct file *filep, int on)
  {
  	struct uio_listener *listener = filep->private_data;
  	struct uio_device *idev = listener->dev;
  
  	return fasync_helper(fd, filep, on, &idev->async_queue);
  }
  
  static int uio_release(struct inode *inode, struct file *filep)
  {
  	int ret = 0;
  	struct uio_listener *listener = filep->private_data;
  	struct uio_device *idev = listener->dev;

  	if (idev->info->release)

  		ret = idev->info->release(idev->info, inode);

  
  	module_put(idev->owner);

  	kfree(listener);
  	return ret;
  }
  
  static unsigned int uio_poll(struct file *filep, poll_table *wait)
  {
  	struct uio_listener *listener = filep->private_data;
  	struct uio_device *idev = listener->dev;
  
  	if (idev->info->irq == UIO_IRQ_NONE)
  		return -EIO;
  
  	poll_wait(filep, &idev->wait, wait);
  	if (listener->event_count != atomic_read(&idev->event))
  		return POLLIN | POLLRDNORM;
  	return 0;
  }
  
  static ssize_t uio_read(struct file *filep, char __user *buf,
  			size_t count, loff_t *ppos)
  {
  	struct uio_listener *listener = filep->private_data;
  	struct uio_device *idev = listener->dev;
  	DECLARE_WAITQUEUE(wait, current);
  	ssize_t retval;
  	s32 event_count;
  
  	if (idev->info->irq == UIO_IRQ_NONE)
  		return -EIO;
  
  	if (count != sizeof(s32))
  		return -EINVAL;
  
  	add_wait_queue(&idev->wait, &wait);
  
  	do {
  		set_current_state(TASK_INTERRUPTIBLE);
  
  		event_count = atomic_read(&idev->event);
  		if (event_count != listener->event_count) {
  			if (copy_to_user(buf, &event_count, count))
  				retval = -EFAULT;
  			else {
  				listener->event_count = event_count;
  				retval = count;
  			}
  			break;
  		}
  
  		if (filep->f_flags & O_NONBLOCK) {
  			retval = -EAGAIN;
  			break;
  		}
  
  		if (signal_pending(current)) {
  			retval = -ERESTARTSYS;
  			break;
  		}
  		schedule();
  	} while (1);
  
  	__set_current_state(TASK_RUNNING);
  	remove_wait_queue(&idev->wait, &wait);
  
  	return retval;
  }

  static ssize_t uio_write(struct file *filep, const char __user *buf,
  			size_t count, loff_t *ppos)
  {
  	struct uio_listener *listener = filep->private_data;
  	struct uio_device *idev = listener->dev;
  	ssize_t retval;
  	s32 irq_on;
  
  	if (idev->info->irq == UIO_IRQ_NONE)
  		return -EIO;
  
  	if (count != sizeof(s32))
  		return -EINVAL;
  
  	if (!idev->info->irqcontrol)
  		return -ENOSYS;
  
  	if (copy_from_user(&irq_on, buf, count))
  		return -EFAULT;
  
  	retval = idev->info->irqcontrol(idev->info, irq_on);
  
  	return retval ? retval : sizeof(s32);
  }

  static int uio_find_mem_index(struct vm_area_struct *vma)
  {
  	int mi;
  	struct uio_device *idev = vma->vm_private_data;
  
  	for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
  		if (idev->info->mem[mi].size == 0)
  			return -1;
  		if (vma->vm_pgoff == mi)
  			return mi;
  	}
  	return -1;
  }
  
  static void uio_vma_open(struct vm_area_struct *vma)
  {
  	struct uio_device *idev = vma->vm_private_data;
  	idev->vma_count++;
  }
  
  static void uio_vma_close(struct vm_area_struct *vma)
  {
  	struct uio_device *idev = vma->vm_private_data;
  	idev->vma_count--;
  }

  static int uio_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)

  {
  	struct uio_device *idev = vma->vm_private_data;

  	struct page *page;

  	unsigned long offset;

  
  	int mi = uio_find_mem_index(vma);
  	if (mi < 0)

  		return VM_FAULT_SIGBUS;

  	/*
  	 * We need to subtract mi because userspace uses offset = N*PAGE_SIZE
  	 * to use mem[N].
  	 */
  	offset = (vmf->pgoff - mi) << PAGE_SHIFT;

  	if (idev->info->mem[mi].memtype == UIO_MEM_LOGICAL)

  		page = virt_to_page(idev->info->mem[mi].addr + offset);

  	else

  		page = vmalloc_to_page((void *)idev->info->mem[mi].addr
  							+ offset);

  	get_page(page);

  	vmf->page = page;
  	return 0;

  }

  static const struct vm_operations_struct uio_vm_ops = {

  	.open = uio_vma_open,
  	.close = uio_vma_close,

  	.fault = uio_vma_fault,

  };
  
  static int uio_mmap_physical(struct vm_area_struct *vma)
  {
  	struct uio_device *idev = vma->vm_private_data;
  	int mi = uio_find_mem_index(vma);
  	if (mi < 0)
  		return -EINVAL;
  
  	vma->vm_flags |= VM_IO | VM_RESERVED;

  
  	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);

  
  	return remap_pfn_range(vma,
  			       vma->vm_start,
  			       idev->info->mem[mi].addr >> PAGE_SHIFT,
  			       vma->vm_end - vma->vm_start,
  			       vma->vm_page_prot);
  }
  
  static int uio_mmap_logical(struct vm_area_struct *vma)
  {
  	vma->vm_flags |= VM_RESERVED;
  	vma->vm_ops = &uio_vm_ops;
  	uio_vma_open(vma);
  	return 0;
  }
  
  static int uio_mmap(struct file *filep, struct vm_area_struct *vma)
  {
  	struct uio_listener *listener = filep->private_data;
  	struct uio_device *idev = listener->dev;
  	int mi;
  	unsigned long requested_pages, actual_pages;
  	int ret = 0;
  
  	if (vma->vm_end < vma->vm_start)
  		return -EINVAL;
  
  	vma->vm_private_data = idev;
  
  	mi = uio_find_mem_index(vma);
  	if (mi < 0)
  		return -EINVAL;
  
  	requested_pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;

  	actual_pages = ((idev->info->mem[mi].addr & ~PAGE_MASK)
  			+ idev->info->mem[mi].size + PAGE_SIZE -1) >> PAGE_SHIFT;

  	if (requested_pages > actual_pages)
  		return -EINVAL;
  
  	if (idev->info->mmap) {

  		ret = idev->info->mmap(idev->info, vma);

  		return ret;
  	}
  
  	switch (idev->info->mem[mi].memtype) {
  		case UIO_MEM_PHYS:
  			return uio_mmap_physical(vma);
  		case UIO_MEM_LOGICAL:
  		case UIO_MEM_VIRTUAL:
  			return uio_mmap_logical(vma);
  		default:
  			return -EINVAL;
  	}
  }

  static const struct file_operations uio_fops = {

  	.owner		= THIS_MODULE,
  	.open		= uio_open,
  	.release	= uio_release,
  	.read		= uio_read,

  	.write		= uio_write,

  	.mmap		= uio_mmap,
  	.poll		= uio_poll,
  	.fasync		= uio_fasync,
  };
  
  static int uio_major_init(void)
  {
  	uio_major = register_chrdev(0, "uio", &uio_fops);
  	if (uio_major < 0)
  		return uio_major;
  	return 0;
  }
  
  static void uio_major_cleanup(void)
  {
  	unregister_chrdev(uio_major, "uio");
  }
  
  static int init_uio_class(void)
  {
  	int ret = 0;
  
  	if (uio_class != NULL) {
  		kref_get(&uio_class->kref);
  		goto exit;
  	}
  
  	/* This is the first time in here, set everything up properly */
  	ret = uio_major_init();
  	if (ret)
  		goto exit;
  
  	uio_class = kzalloc(sizeof(*uio_class), GFP_KERNEL);
  	if (!uio_class) {
  		ret = -ENOMEM;
  		goto err_kzalloc;
  	}
  
  	kref_init(&uio_class->kref);
  	uio_class->class = class_create(THIS_MODULE, "uio");
  	if (IS_ERR(uio_class->class)) {
  		ret = IS_ERR(uio_class->class);
  		printk(KERN_ERR "class_create failed for uio
  ");
  		goto err_class_create;
  	}
  	return 0;
  
  err_class_create:
  	kfree(uio_class);
  	uio_class = NULL;
  err_kzalloc:
  	uio_major_cleanup();
  exit:
  	return ret;
  }
  
  static void release_uio_class(struct kref *kref)
  {
  	/* Ok, we cheat as we know we only have one uio_class */
  	class_destroy(uio_class->class);
  	kfree(uio_class);
  	uio_major_cleanup();
  	uio_class = NULL;
  }
  
  static void uio_class_destroy(void)
  {
  	if (uio_class)
  		kref_put(&uio_class->kref, release_uio_class);
  }
  
  /**
   * uio_register_device - register a new userspace IO device
   * @owner:	module that creates the new device
   * @parent:	parent device
   * @info:	UIO device capabilities
   *
   * returns zero on success or a negative error code.
   */
  int __uio_register_device(struct module *owner,
  			  struct device *parent,
  			  struct uio_info *info)
  {
  	struct uio_device *idev;
  	int ret = 0;
  
  	if (!parent || !info || !info->name || !info->version)
  		return -EINVAL;
  
  	info->uio_dev = NULL;
  
  	ret = init_uio_class();
  	if (ret)
  		return ret;
  
  	idev = kzalloc(sizeof(*idev), GFP_KERNEL);
  	if (!idev) {
  		ret = -ENOMEM;
  		goto err_kzalloc;
  	}
  
  	idev->owner = owner;
  	idev->info = info;
  	init_waitqueue_head(&idev->wait);
  	atomic_set(&idev->event, 0);
  
  	ret = uio_get_minor(idev);
  	if (ret)
  		goto err_get_minor;

  	idev->dev = device_create(uio_class->class, parent,
  				  MKDEV(uio_major, idev->minor), idev,
  				  "uio%d", idev->minor);

  	if (IS_ERR(idev->dev)) {
  		printk(KERN_ERR "UIO: device register failed
  ");
  		ret = PTR_ERR(idev->dev);
  		goto err_device_create;
  	}

  
  	ret = uio_dev_add_attributes(idev);
  	if (ret)
  		goto err_uio_dev_add_attributes;
  
  	info->uio_dev = idev;
  
  	if (idev->info->irq >= 0) {
  		ret = request_irq(idev->info->irq, uio_interrupt,
  				  idev->info->irq_flags, idev->info->name, idev);
  		if (ret)
  			goto err_request_irq;
  	}
  
  	return 0;
  
  err_request_irq:
  	uio_dev_del_attributes(idev);
  err_uio_dev_add_attributes:
  	device_destroy(uio_class->class, MKDEV(uio_major, idev->minor));
  err_device_create:
  	uio_free_minor(idev);
  err_get_minor:
  	kfree(idev);
  err_kzalloc:
  	uio_class_destroy();
  	return ret;
  }
  EXPORT_SYMBOL_GPL(__uio_register_device);
  
  /**
   * uio_unregister_device - unregister a industrial IO device
   * @info:	UIO device capabilities
   *
   */
  void uio_unregister_device(struct uio_info *info)
  {
  	struct uio_device *idev;
  
  	if (!info || !info->uio_dev)
  		return;
  
  	idev = info->uio_dev;
  
  	uio_free_minor(idev);
  
  	if (info->irq >= 0)
  		free_irq(info->irq, idev);
  
  	uio_dev_del_attributes(idev);
  
  	dev_set_drvdata(idev->dev, NULL);
  	device_destroy(uio_class->class, MKDEV(uio_major, idev->minor));
  	kfree(idev);
  	uio_class_destroy();
  
  	return;
  }
  EXPORT_SYMBOL_GPL(uio_unregister_device);
  
  static int __init uio_init(void)
  {
  	return 0;
  }
  
  static void __exit uio_exit(void)
  {
  }
  
  module_init(uio_init)
  module_exit(uio_exit)
  MODULE_LICENSE("GPL v2");