xref: /linux/drivers/uio/uio.c (revision b233b28eac0cc37d07c2d007ea08c86c778c5af4) 
1 /*
2  * drivers/uio/uio.c
3  *
4  * Copyright(C) 2005, Benedikt Spranger <b.spranger@linutronix.de>
5  * Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
6  * Copyright(C) 2006, Hans J. Koch <hjk@linutronix.de>
7  * Copyright(C) 2006, Greg Kroah-Hartman <greg@kroah.com>
8  *
9  * Userspace IO
10  *
11  * Base Functions
12  *
13  * Licensed under the GPLv2 only.
14  */
15 
16 #include <linux/module.h>
17 #include <linux/init.h>
18 #include <linux/poll.h>
19 #include <linux/device.h>
20 #include <linux/mm.h>
21 #include <linux/idr.h>
22 #include <linux/string.h>
23 #include <linux/kobject.h>
24 #include <linux/uio_driver.h>
25 
26 #define UIO_MAX_DEVICES 255
27 
28 struct uio_device {
29 	struct module		*owner;
30 	struct device		*dev;
31 	int			minor;
32 	atomic_t		event;
33 	struct fasync_struct	*async_queue;
34 	wait_queue_head_t	wait;
35 	int			vma_count;
36 	struct uio_info		*info;
37 	struct kobject		*map_dir;
38 	struct kobject		*portio_dir;
39 };
40 
41 static int uio_major;
42 static DEFINE_IDR(uio_idr);
43 static const struct file_operations uio_fops;
44 
45 /* UIO class infrastructure */
46 static struct uio_class {
47 	struct kref kref;
48 	struct class *class;
49 } *uio_class;
50 
51 /* Protect idr accesses */
52 static DEFINE_MUTEX(minor_lock);
53 
54 /*
55  * attributes
56  */
57 
58 struct uio_map {
59 	struct kobject kobj;
60 	struct uio_mem *mem;
61 };
62 #define to_map(map) container_of(map, struct uio_map, kobj)
63 
64 static ssize_t map_addr_show(struct uio_mem *mem, char *buf)
65 {
66 	return sprintf(buf, "0x%lx\n", mem->addr);
67 }
68 
69 static ssize_t map_size_show(struct uio_mem *mem, char *buf)
70 {
71 	return sprintf(buf, "0x%lx\n", mem->size);
72 }
73 
74 static ssize_t map_offset_show(struct uio_mem *mem, char *buf)
75 {
76 	return sprintf(buf, "0x%lx\n", mem->addr & ~PAGE_MASK);
77 }
78 
79 struct map_sysfs_entry {
80 	struct attribute attr;
81 	ssize_t (*show)(struct uio_mem *, char *);
82 	ssize_t (*store)(struct uio_mem *, const char *, size_t);
83 };
84 
85 static struct map_sysfs_entry addr_attribute =
86 	__ATTR(addr, S_IRUGO, map_addr_show, NULL);
87 static struct map_sysfs_entry size_attribute =
88 	__ATTR(size, S_IRUGO, map_size_show, NULL);
89 static struct map_sysfs_entry offset_attribute =
90 	__ATTR(offset, S_IRUGO, map_offset_show, NULL);
91 
92 static struct attribute *attrs[] = {
93 	&addr_attribute.attr,
94 	&size_attribute.attr,
95 	&offset_attribute.attr,
96 	NULL,	/* need to NULL terminate the list of attributes */
97 };
98 
99 static void map_release(struct kobject *kobj)
100 {
101 	struct uio_map *map = to_map(kobj);
102 	kfree(map);
103 }
104 
105 static ssize_t map_type_show(struct kobject *kobj, struct attribute *attr,
106 			     char *buf)
107 {
108 	struct uio_map *map = to_map(kobj);
109 	struct uio_mem *mem = map->mem;
110 	struct map_sysfs_entry *entry;
111 
112 	entry = container_of(attr, struct map_sysfs_entry, attr);
113 
114 	if (!entry->show)
115 		return -EIO;
116 
117 	return entry->show(mem, buf);
118 }
119 
120 static struct sysfs_ops map_sysfs_ops = {
121 	.show = map_type_show,
122 };
123 
124 static struct kobj_type map_attr_type = {
125 	.release	= map_release,
126 	.sysfs_ops	= &map_sysfs_ops,
127 	.default_attrs	= attrs,
128 };
129 
130 struct uio_portio {
131 	struct kobject kobj;
132 	struct uio_port *port;
133 };
134 #define to_portio(portio) container_of(portio, struct uio_portio, kobj)
135 
136 static ssize_t portio_start_show(struct uio_port *port, char *buf)
137 {
138 	return sprintf(buf, "0x%lx\n", port->start);
139 }
140 
141 static ssize_t portio_size_show(struct uio_port *port, char *buf)
142 {
143 	return sprintf(buf, "0x%lx\n", port->size);
144 }
145 
146 static ssize_t portio_porttype_show(struct uio_port *port, char *buf)
147 {
148 	const char *porttypes[] = {"none", "x86", "gpio", "other"};
149 
150 	if ((port->porttype < 0) || (port->porttype > UIO_PORT_OTHER))
151 		return -EINVAL;
152 
153 	return sprintf(buf, "port_%s\n", porttypes[port->porttype]);
154 }
155 
156 struct portio_sysfs_entry {
157 	struct attribute attr;
158 	ssize_t (*show)(struct uio_port *, char *);
159 	ssize_t (*store)(struct uio_port *, const char *, size_t);
160 };
161 
162 static struct portio_sysfs_entry portio_start_attribute =
163 	__ATTR(start, S_IRUGO, portio_start_show, NULL);
164 static struct portio_sysfs_entry portio_size_attribute =
165 	__ATTR(size, S_IRUGO, portio_size_show, NULL);
166 static struct portio_sysfs_entry portio_porttype_attribute =
167 	__ATTR(porttype, S_IRUGO, portio_porttype_show, NULL);
168 
169 static struct attribute *portio_attrs[] = {
170 	&portio_start_attribute.attr,
171 	&portio_size_attribute.attr,
172 	&portio_porttype_attribute.attr,
173 	NULL,
174 };
175 
176 static void portio_release(struct kobject *kobj)
177 {
178 	struct uio_portio *portio = to_portio(kobj);
179 	kfree(portio);
180 }
181 
182 static ssize_t portio_type_show(struct kobject *kobj, struct attribute *attr,
183 			     char *buf)
184 {
185 	struct uio_portio *portio = to_portio(kobj);
186 	struct uio_port *port = portio->port;
187 	struct portio_sysfs_entry *entry;
188 
189 	entry = container_of(attr, struct portio_sysfs_entry, attr);
190 
191 	if (!entry->show)
192 		return -EIO;
193 
194 	return entry->show(port, buf);
195 }
196 
197 static struct sysfs_ops portio_sysfs_ops = {
198 	.show = portio_type_show,
199 };
200 
201 static struct kobj_type portio_attr_type = {
202 	.release	= portio_release,
203 	.sysfs_ops	= &portio_sysfs_ops,
204 	.default_attrs	= portio_attrs,
205 };
206 
207 static ssize_t show_name(struct device *dev,
208 			 struct device_attribute *attr, char *buf)
209 {
210 	struct uio_device *idev = dev_get_drvdata(dev);
211 	if (idev)
212 		return sprintf(buf, "%s\n", idev->info->name);
213 	else
214 		return -ENODEV;
215 }
216 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
217 
218 static ssize_t show_version(struct device *dev,
219 			    struct device_attribute *attr, char *buf)
220 {
221 	struct uio_device *idev = dev_get_drvdata(dev);
222 	if (idev)
223 		return sprintf(buf, "%s\n", idev->info->version);
224 	else
225 		return -ENODEV;
226 }
227 static DEVICE_ATTR(version, S_IRUGO, show_version, NULL);
228 
229 static ssize_t show_event(struct device *dev,
230 			  struct device_attribute *attr, char *buf)
231 {
232 	struct uio_device *idev = dev_get_drvdata(dev);
233 	if (idev)
234 		return sprintf(buf, "%u\n",
235 				(unsigned int)atomic_read(&idev->event));
236 	else
237 		return -ENODEV;
238 }
239 static DEVICE_ATTR(event, S_IRUGO, show_event, NULL);
240 
241 static struct attribute *uio_attrs[] = {
242 	&dev_attr_name.attr,
243 	&dev_attr_version.attr,
244 	&dev_attr_event.attr,
245 	NULL,
246 };
247 
248 static struct attribute_group uio_attr_grp = {
249 	.attrs = uio_attrs,
250 };
251 
252 /*
253  * device functions
254  */
255 static int uio_dev_add_attributes(struct uio_device *idev)
256 {
257 	int ret;
258 	int mi, pi;
259 	int map_found = 0;
260 	int portio_found = 0;
261 	struct uio_mem *mem;
262 	struct uio_map *map;
263 	struct uio_port *port;
264 	struct uio_portio *portio;
265 
266 	ret = sysfs_create_group(&idev->dev->kobj, &uio_attr_grp);
267 	if (ret)
268 		goto err_group;
269 
270 	for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
271 		mem = &idev->info->mem[mi];
272 		if (mem->size == 0)
273 			break;
274 		if (!map_found) {
275 			map_found = 1;
276 			idev->map_dir = kobject_create_and_add("maps",
277 							&idev->dev->kobj);
278 			if (!idev->map_dir)
279 				goto err_map;
280 		}
281 		map = kzalloc(sizeof(*map), GFP_KERNEL);
282 		if (!map)
283 			goto err_map;
284 		kobject_init(&map->kobj, &map_attr_type);
285 		map->mem = mem;
286 		mem->map = map;
287 		ret = kobject_add(&map->kobj, idev->map_dir, "map%d", mi);
288 		if (ret)
289 			goto err_map;
290 		ret = kobject_uevent(&map->kobj, KOBJ_ADD);
291 		if (ret)
292 			goto err_map;
293 	}
294 
295 	for (pi = 0; pi < MAX_UIO_PORT_REGIONS; pi++) {
296 		port = &idev->info->port[pi];
297 		if (port->size == 0)
298 			break;
299 		if (!portio_found) {
300 			portio_found = 1;
301 			idev->portio_dir = kobject_create_and_add("portio",
302 							&idev->dev->kobj);
303 			if (!idev->portio_dir)
304 				goto err_portio;
305 		}
306 		portio = kzalloc(sizeof(*portio), GFP_KERNEL);
307 		if (!portio)
308 			goto err_portio;
309 		kobject_init(&portio->kobj, &portio_attr_type);
310 		portio->port = port;
311 		port->portio = portio;
312 		ret = kobject_add(&portio->kobj, idev->portio_dir,
313 							"port%d", pi);
314 		if (ret)
315 			goto err_portio;
316 		ret = kobject_uevent(&portio->kobj, KOBJ_ADD);
317 		if (ret)
318 			goto err_portio;
319 	}
320 
321 	return 0;
322 
323 err_portio:
324 	for (pi--; pi >= 0; pi--) {
325 		port = &idev->info->port[pi];
326 		portio = port->portio;
327 		kobject_put(&portio->kobj);
328 	}
329 	kobject_put(idev->portio_dir);
330 err_map:
331 	for (mi--; mi>=0; mi--) {
332 		mem = &idev->info->mem[mi];
333 		map = mem->map;
334 		kobject_put(&map->kobj);
335 	}
336 	kobject_put(idev->map_dir);
337 	sysfs_remove_group(&idev->dev->kobj, &uio_attr_grp);
338 err_group:
339 	dev_err(idev->dev, "error creating sysfs files (%d)\n", ret);
340 	return ret;
341 }
342 
343 static void uio_dev_del_attributes(struct uio_device *idev)
344 {
345 	int i;
346 	struct uio_mem *mem;
347 	struct uio_port *port;
348 
349 	for (i = 0; i < MAX_UIO_MAPS; i++) {
350 		mem = &idev->info->mem[i];
351 		if (mem->size == 0)
352 			break;
353 		kobject_put(&mem->map->kobj);
354 	}
355 	kobject_put(idev->map_dir);
356 
357 	for (i = 0; i < MAX_UIO_PORT_REGIONS; i++) {
358 		port = &idev->info->port[i];
359 		if (port->size == 0)
360 			break;
361 		kobject_put(&port->portio->kobj);
362 	}
363 	kobject_put(idev->portio_dir);
364 
365 	sysfs_remove_group(&idev->dev->kobj, &uio_attr_grp);
366 }
367 
368 static int uio_get_minor(struct uio_device *idev)
369 {
370 	int retval = -ENOMEM;
371 	int id;
372 
373 	mutex_lock(&minor_lock);
374 	if (idr_pre_get(&uio_idr, GFP_KERNEL) == 0)
375 		goto exit;
376 
377 	retval = idr_get_new(&uio_idr, idev, &id);
378 	if (retval < 0) {
379 		if (retval == -EAGAIN)
380 			retval = -ENOMEM;
381 		goto exit;
382 	}
383 	idev->minor = id & MAX_ID_MASK;
384 exit:
385 	mutex_unlock(&minor_lock);
386 	return retval;
387 }
388 
389 static void uio_free_minor(struct uio_device *idev)
390 {
391 	mutex_lock(&minor_lock);
392 	idr_remove(&uio_idr, idev->minor);
393 	mutex_unlock(&minor_lock);
394 }
395 
396 /**
397  * uio_event_notify - trigger an interrupt event
398  * @info: UIO device capabilities
399  */
400 void uio_event_notify(struct uio_info *info)
401 {
402 	struct uio_device *idev = info->uio_dev;
403 
404 	atomic_inc(&idev->event);
405 	wake_up_interruptible(&idev->wait);
406 	kill_fasync(&idev->async_queue, SIGIO, POLL_IN);
407 }
408 EXPORT_SYMBOL_GPL(uio_event_notify);
409 
410 /**
411  * uio_interrupt - hardware interrupt handler
412  * @irq: IRQ number, can be UIO_IRQ_CYCLIC for cyclic timer
413  * @dev_id: Pointer to the devices uio_device structure
414  */
415 static irqreturn_t uio_interrupt(int irq, void *dev_id)
416 {
417 	struct uio_device *idev = (struct uio_device *)dev_id;
418 	irqreturn_t ret = idev->info->handler(irq, idev->info);
419 
420 	if (ret == IRQ_HANDLED)
421 		uio_event_notify(idev->info);
422 
423 	return ret;
424 }
425 
426 struct uio_listener {
427 	struct uio_device *dev;
428 	s32 event_count;
429 };
430 
431 static int uio_open(struct inode *inode, struct file *filep)
432 {
433 	struct uio_device *idev;
434 	struct uio_listener *listener;
435 	int ret = 0;
436 
437 	mutex_lock(&minor_lock);
438 	idev = idr_find(&uio_idr, iminor(inode));
439 	mutex_unlock(&minor_lock);
440 	if (!idev) {
441 		ret = -ENODEV;
442 		goto out;
443 	}
444 
445 	if (!try_module_get(idev->owner)) {
446 		ret = -ENODEV;
447 		goto out;
448 	}
449 
450 	listener = kmalloc(sizeof(*listener), GFP_KERNEL);
451 	if (!listener) {
452 		ret = -ENOMEM;
453 		goto err_alloc_listener;
454 	}
455 
456 	listener->dev = idev;
457 	listener->event_count = atomic_read(&idev->event);
458 	filep->private_data = listener;
459 
460 	if (idev->info->open) {
461 		ret = idev->info->open(idev->info, inode);
462 		if (ret)
463 			goto err_infoopen;
464 	}
465 	return 0;
466 
467 err_infoopen:
468 	kfree(listener);
469 
470 err_alloc_listener:
471 	module_put(idev->owner);
472 
473 out:
474 	return ret;
475 }
476 
477 static int uio_fasync(int fd, struct file *filep, int on)
478 {
479 	struct uio_listener *listener = filep->private_data;
480 	struct uio_device *idev = listener->dev;
481 
482 	return fasync_helper(fd, filep, on, &idev->async_queue);
483 }
484 
485 static int uio_release(struct inode *inode, struct file *filep)
486 {
487 	int ret = 0;
488 	struct uio_listener *listener = filep->private_data;
489 	struct uio_device *idev = listener->dev;
490 
491 	if (idev->info->release)
492 		ret = idev->info->release(idev->info, inode);
493 
494 	module_put(idev->owner);
495 	kfree(listener);
496 	return ret;
497 }
498 
499 static unsigned int uio_poll(struct file *filep, poll_table *wait)
500 {
501 	struct uio_listener *listener = filep->private_data;
502 	struct uio_device *idev = listener->dev;
503 
504 	if (idev->info->irq == UIO_IRQ_NONE)
505 		return -EIO;
506 
507 	poll_wait(filep, &idev->wait, wait);
508 	if (listener->event_count != atomic_read(&idev->event))
509 		return POLLIN | POLLRDNORM;
510 	return 0;
511 }
512 
513 static ssize_t uio_read(struct file *filep, char __user *buf,
514 			size_t count, loff_t *ppos)
515 {
516 	struct uio_listener *listener = filep->private_data;
517 	struct uio_device *idev = listener->dev;
518 	DECLARE_WAITQUEUE(wait, current);
519 	ssize_t retval;
520 	s32 event_count;
521 
522 	if (idev->info->irq == UIO_IRQ_NONE)
523 		return -EIO;
524 
525 	if (count != sizeof(s32))
526 		return -EINVAL;
527 
528 	add_wait_queue(&idev->wait, &wait);
529 
530 	do {
531 		set_current_state(TASK_INTERRUPTIBLE);
532 
533 		event_count = atomic_read(&idev->event);
534 		if (event_count != listener->event_count) {
535 			if (copy_to_user(buf, &event_count, count))
536 				retval = -EFAULT;
537 			else {
538 				listener->event_count = event_count;
539 				retval = count;
540 			}
541 			break;
542 		}
543 
544 		if (filep->f_flags & O_NONBLOCK) {
545 			retval = -EAGAIN;
546 			break;
547 		}
548 
549 		if (signal_pending(current)) {
550 			retval = -ERESTARTSYS;
551 			break;
552 		}
553 		schedule();
554 	} while (1);
555 
556 	__set_current_state(TASK_RUNNING);
557 	remove_wait_queue(&idev->wait, &wait);
558 
559 	return retval;
560 }
561 
562 static ssize_t uio_write(struct file *filep, const char __user *buf,
563 			size_t count, loff_t *ppos)
564 {
565 	struct uio_listener *listener = filep->private_data;
566 	struct uio_device *idev = listener->dev;
567 	ssize_t retval;
568 	s32 irq_on;
569 
570 	if (idev->info->irq == UIO_IRQ_NONE)
571 		return -EIO;
572 
573 	if (count != sizeof(s32))
574 		return -EINVAL;
575 
576 	if (!idev->info->irqcontrol)
577 		return -ENOSYS;
578 
579 	if (copy_from_user(&irq_on, buf, count))
580 		return -EFAULT;
581 
582 	retval = idev->info->irqcontrol(idev->info, irq_on);
583 
584 	return retval ? retval : sizeof(s32);
585 }
586 
587 static int uio_find_mem_index(struct vm_area_struct *vma)
588 {
589 	int mi;
590 	struct uio_device *idev = vma->vm_private_data;
591 
592 	for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
593 		if (idev->info->mem[mi].size == 0)
594 			return -1;
595 		if (vma->vm_pgoff == mi)
596 			return mi;
597 	}
598 	return -1;
599 }
600 
601 static void uio_vma_open(struct vm_area_struct *vma)
602 {
603 	struct uio_device *idev = vma->vm_private_data;
604 	idev->vma_count++;
605 }
606 
607 static void uio_vma_close(struct vm_area_struct *vma)
608 {
609 	struct uio_device *idev = vma->vm_private_data;
610 	idev->vma_count--;
611 }
612 
613 static int uio_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
614 {
615 	struct uio_device *idev = vma->vm_private_data;
616 	struct page *page;
617 	unsigned long offset;
618 
619 	int mi = uio_find_mem_index(vma);
620 	if (mi < 0)
621 		return VM_FAULT_SIGBUS;
622 
623 	/*
624 	 * We need to subtract mi because userspace uses offset = N*PAGE_SIZE
625 	 * to use mem[N].
626 	 */
627 	offset = (vmf->pgoff - mi) << PAGE_SHIFT;
628 
629 	if (idev->info->mem[mi].memtype == UIO_MEM_LOGICAL)
630 		page = virt_to_page(idev->info->mem[mi].addr + offset);
631 	else
632 		page = vmalloc_to_page((void *)idev->info->mem[mi].addr
633 							+ offset);
634 	get_page(page);
635 	vmf->page = page;
636 	return 0;
637 }
638 
639 static struct vm_operations_struct uio_vm_ops = {
640 	.open = uio_vma_open,
641 	.close = uio_vma_close,
642 	.fault = uio_vma_fault,
643 };
644 
645 static int uio_mmap_physical(struct vm_area_struct *vma)
646 {
647 	struct uio_device *idev = vma->vm_private_data;
648 	int mi = uio_find_mem_index(vma);
649 	if (mi < 0)
650 		return -EINVAL;
651 
652 	vma->vm_flags |= VM_IO | VM_RESERVED;
653 
654 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
655 
656 	return remap_pfn_range(vma,
657 			       vma->vm_start,
658 			       idev->info->mem[mi].addr >> PAGE_SHIFT,
659 			       vma->vm_end - vma->vm_start,
660 			       vma->vm_page_prot);
661 }
662 
663 static int uio_mmap_logical(struct vm_area_struct *vma)
664 {
665 	vma->vm_flags |= VM_RESERVED;
666 	vma->vm_ops = &uio_vm_ops;
667 	uio_vma_open(vma);
668 	return 0;
669 }
670 
671 static int uio_mmap(struct file *filep, struct vm_area_struct *vma)
672 {
673 	struct uio_listener *listener = filep->private_data;
674 	struct uio_device *idev = listener->dev;
675 	int mi;
676 	unsigned long requested_pages, actual_pages;
677 	int ret = 0;
678 
679 	if (vma->vm_end < vma->vm_start)
680 		return -EINVAL;
681 
682 	vma->vm_private_data = idev;
683 
684 	mi = uio_find_mem_index(vma);
685 	if (mi < 0)
686 		return -EINVAL;
687 
688 	requested_pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
689 	actual_pages = (idev->info->mem[mi].size + PAGE_SIZE -1) >> PAGE_SHIFT;
690 	if (requested_pages > actual_pages)
691 		return -EINVAL;
692 
693 	if (idev->info->mmap) {
694 		ret = idev->info->mmap(idev->info, vma);
695 		return ret;
696 	}
697 
698 	switch (idev->info->mem[mi].memtype) {
699 		case UIO_MEM_PHYS:
700 			return uio_mmap_physical(vma);
701 		case UIO_MEM_LOGICAL:
702 		case UIO_MEM_VIRTUAL:
703 			return uio_mmap_logical(vma);
704 		default:
705 			return -EINVAL;
706 	}
707 }
708 
709 static const struct file_operations uio_fops = {
710 	.owner		= THIS_MODULE,
711 	.open		= uio_open,
712 	.release	= uio_release,
713 	.read		= uio_read,
714 	.write		= uio_write,
715 	.mmap		= uio_mmap,
716 	.poll		= uio_poll,
717 	.fasync		= uio_fasync,
718 };
719 
720 static int uio_major_init(void)
721 {
722 	uio_major = register_chrdev(0, "uio", &uio_fops);
723 	if (uio_major < 0)
724 		return uio_major;
725 	return 0;
726 }
727 
728 static void uio_major_cleanup(void)
729 {
730 	unregister_chrdev(uio_major, "uio");
731 }
732 
733 static int init_uio_class(void)
734 {
735 	int ret = 0;
736 
737 	if (uio_class != NULL) {
738 		kref_get(&uio_class->kref);
739 		goto exit;
740 	}
741 
742 	/* This is the first time in here, set everything up properly */
743 	ret = uio_major_init();
744 	if (ret)
745 		goto exit;
746 
747 	uio_class = kzalloc(sizeof(*uio_class), GFP_KERNEL);
748 	if (!uio_class) {
749 		ret = -ENOMEM;
750 		goto err_kzalloc;
751 	}
752 
753 	kref_init(&uio_class->kref);
754 	uio_class->class = class_create(THIS_MODULE, "uio");
755 	if (IS_ERR(uio_class->class)) {
756 		ret = IS_ERR(uio_class->class);
757 		printk(KERN_ERR "class_create failed for uio\n");
758 		goto err_class_create;
759 	}
760 	return 0;
761 
762 err_class_create:
763 	kfree(uio_class);
764 	uio_class = NULL;
765 err_kzalloc:
766 	uio_major_cleanup();
767 exit:
768 	return ret;
769 }
770 
771 static void release_uio_class(struct kref *kref)
772 {
773 	/* Ok, we cheat as we know we only have one uio_class */
774 	class_destroy(uio_class->class);
775 	kfree(uio_class);
776 	uio_major_cleanup();
777 	uio_class = NULL;
778 }
779 
780 static void uio_class_destroy(void)
781 {
782 	if (uio_class)
783 		kref_put(&uio_class->kref, release_uio_class);
784 }
785 
786 /**
787  * uio_register_device - register a new userspace IO device
788  * @owner:	module that creates the new device
789  * @parent:	parent device
790  * @info:	UIO device capabilities
791  *
792  * returns zero on success or a negative error code.
793  */
794 int __uio_register_device(struct module *owner,
795 			  struct device *parent,
796 			  struct uio_info *info)
797 {
798 	struct uio_device *idev;
799 	int ret = 0;
800 
801 	if (!parent || !info || !info->name || !info->version)
802 		return -EINVAL;
803 
804 	info->uio_dev = NULL;
805 
806 	ret = init_uio_class();
807 	if (ret)
808 		return ret;
809 
810 	idev = kzalloc(sizeof(*idev), GFP_KERNEL);
811 	if (!idev) {
812 		ret = -ENOMEM;
813 		goto err_kzalloc;
814 	}
815 
816 	idev->owner = owner;
817 	idev->info = info;
818 	init_waitqueue_head(&idev->wait);
819 	atomic_set(&idev->event, 0);
820 
821 	ret = uio_get_minor(idev);
822 	if (ret)
823 		goto err_get_minor;
824 
825 	idev->dev = device_create(uio_class->class, parent,
826 				  MKDEV(uio_major, idev->minor), idev,
827 				  "uio%d", idev->minor);
828 	if (IS_ERR(idev->dev)) {
829 		printk(KERN_ERR "UIO: device register failed\n");
830 		ret = PTR_ERR(idev->dev);
831 		goto err_device_create;
832 	}
833 
834 	ret = uio_dev_add_attributes(idev);
835 	if (ret)
836 		goto err_uio_dev_add_attributes;
837 
838 	info->uio_dev = idev;
839 
840 	if (idev->info->irq >= 0) {
841 		ret = request_irq(idev->info->irq, uio_interrupt,
842 				  idev->info->irq_flags, idev->info->name, idev);
843 		if (ret)
844 			goto err_request_irq;
845 	}
846 
847 	return 0;
848 
849 err_request_irq:
850 	uio_dev_del_attributes(idev);
851 err_uio_dev_add_attributes:
852 	device_destroy(uio_class->class, MKDEV(uio_major, idev->minor));
853 err_device_create:
854 	uio_free_minor(idev);
855 err_get_minor:
856 	kfree(idev);
857 err_kzalloc:
858 	uio_class_destroy();
859 	return ret;
860 }
861 EXPORT_SYMBOL_GPL(__uio_register_device);
862 
863 /**
864  * uio_unregister_device - unregister a industrial IO device
865  * @info:	UIO device capabilities
866  *
867  */
868 void uio_unregister_device(struct uio_info *info)
869 {
870 	struct uio_device *idev;
871 
872 	if (!info || !info->uio_dev)
873 		return;
874 
875 	idev = info->uio_dev;
876 
877 	uio_free_minor(idev);
878 
879 	if (info->irq >= 0)
880 		free_irq(info->irq, idev);
881 
882 	uio_dev_del_attributes(idev);
883 
884 	dev_set_drvdata(idev->dev, NULL);
885 	device_destroy(uio_class->class, MKDEV(uio_major, idev->minor));
886 	kfree(idev);
887 	uio_class_destroy();
888 
889 	return;
890 }
891 EXPORT_SYMBOL_GPL(uio_unregister_device);
892 
893 static int __init uio_init(void)
894 {
895 	return 0;
896 }
897 
898 static void __exit uio_exit(void)
899 {
900 }
901 
902 module_init(uio_init)
903 module_exit(uio_exit)
904 MODULE_LICENSE("GPL v2");
905