xref: /linux/drivers/uio/uio.c (revision b889fcf63cb62e7fdb7816565e28f44dbe4a76a5) 
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@hansjkoch.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/slab.h>
21 #include <linux/mm.h>
22 #include <linux/idr.h>
23 #include <linux/sched.h>
24 #include <linux/string.h>
25 #include <linux/kobject.h>
26 #include <linux/cdev.h>
27 #include <linux/uio_driver.h>
28 
29 #define UIO_MAX_DEVICES		(1U << MINORBITS)
30 
31 struct uio_device {
32 	struct module		*owner;
33 	struct device		*dev;
34 	int			minor;
35 	atomic_t		event;
36 	struct fasync_struct	*async_queue;
37 	wait_queue_head_t	wait;
38 	int			vma_count;
39 	struct uio_info		*info;
40 	struct kobject		*map_dir;
41 	struct kobject		*portio_dir;
42 };
43 
44 static int uio_major;
45 static struct cdev *uio_cdev;
46 static DEFINE_IDR(uio_idr);
47 static const struct file_operations uio_fops;
48 
49 /* Protect idr accesses */
50 static DEFINE_MUTEX(minor_lock);
51 
52 /*
53  * attributes
54  */
55 
56 struct uio_map {
57 	struct kobject kobj;
58 	struct uio_mem *mem;
59 };
60 #define to_map(map) container_of(map, struct uio_map, kobj)
61 
62 static ssize_t map_name_show(struct uio_mem *mem, char *buf)
63 {
64 	if (unlikely(!mem->name))
65 		mem->name = "";
66 
67 	return sprintf(buf, "%s\n", mem->name);
68 }
69 
70 static ssize_t map_addr_show(struct uio_mem *mem, char *buf)
71 {
72 	return sprintf(buf, "0x%llx\n", (unsigned long long)mem->addr);
73 }
74 
75 static ssize_t map_size_show(struct uio_mem *mem, char *buf)
76 {
77 	return sprintf(buf, "0x%lx\n", mem->size);
78 }
79 
80 static ssize_t map_offset_show(struct uio_mem *mem, char *buf)
81 {
82 	return sprintf(buf, "0x%llx\n", (unsigned long long)mem->addr & ~PAGE_MASK);
83 }
84 
85 struct map_sysfs_entry {
86 	struct attribute attr;
87 	ssize_t (*show)(struct uio_mem *, char *);
88 	ssize_t (*store)(struct uio_mem *, const char *, size_t);
89 };
90 
91 static struct map_sysfs_entry name_attribute =
92 	__ATTR(name, S_IRUGO, map_name_show, NULL);
93 static struct map_sysfs_entry addr_attribute =
94 	__ATTR(addr, S_IRUGO, map_addr_show, NULL);
95 static struct map_sysfs_entry size_attribute =
96 	__ATTR(size, S_IRUGO, map_size_show, NULL);
97 static struct map_sysfs_entry offset_attribute =
98 	__ATTR(offset, S_IRUGO, map_offset_show, NULL);
99 
100 static struct attribute *attrs[] = {
101 	&name_attribute.attr,
102 	&addr_attribute.attr,
103 	&size_attribute.attr,
104 	&offset_attribute.attr,
105 	NULL,	/* need to NULL terminate the list of attributes */
106 };
107 
108 static void map_release(struct kobject *kobj)
109 {
110 	struct uio_map *map = to_map(kobj);
111 	kfree(map);
112 }
113 
114 static ssize_t map_type_show(struct kobject *kobj, struct attribute *attr,
115 			     char *buf)
116 {
117 	struct uio_map *map = to_map(kobj);
118 	struct uio_mem *mem = map->mem;
119 	struct map_sysfs_entry *entry;
120 
121 	entry = container_of(attr, struct map_sysfs_entry, attr);
122 
123 	if (!entry->show)
124 		return -EIO;
125 
126 	return entry->show(mem, buf);
127 }
128 
129 static const struct sysfs_ops map_sysfs_ops = {
130 	.show = map_type_show,
131 };
132 
133 static struct kobj_type map_attr_type = {
134 	.release	= map_release,
135 	.sysfs_ops	= &map_sysfs_ops,
136 	.default_attrs	= attrs,
137 };
138 
139 struct uio_portio {
140 	struct kobject kobj;
141 	struct uio_port *port;
142 };
143 #define to_portio(portio) container_of(portio, struct uio_portio, kobj)
144 
145 static ssize_t portio_name_show(struct uio_port *port, char *buf)
146 {
147 	if (unlikely(!port->name))
148 		port->name = "";
149 
150 	return sprintf(buf, "%s\n", port->name);
151 }
152 
153 static ssize_t portio_start_show(struct uio_port *port, char *buf)
154 {
155 	return sprintf(buf, "0x%lx\n", port->start);
156 }
157 
158 static ssize_t portio_size_show(struct uio_port *port, char *buf)
159 {
160 	return sprintf(buf, "0x%lx\n", port->size);
161 }
162 
163 static ssize_t portio_porttype_show(struct uio_port *port, char *buf)
164 {
165 	const char *porttypes[] = {"none", "x86", "gpio", "other"};
166 
167 	if ((port->porttype < 0) || (port->porttype > UIO_PORT_OTHER))
168 		return -EINVAL;
169 
170 	return sprintf(buf, "port_%s\n", porttypes[port->porttype]);
171 }
172 
173 struct portio_sysfs_entry {
174 	struct attribute attr;
175 	ssize_t (*show)(struct uio_port *, char *);
176 	ssize_t (*store)(struct uio_port *, const char *, size_t);
177 };
178 
179 static struct portio_sysfs_entry portio_name_attribute =
180 	__ATTR(name, S_IRUGO, portio_name_show, NULL);
181 static struct portio_sysfs_entry portio_start_attribute =
182 	__ATTR(start, S_IRUGO, portio_start_show, NULL);
183 static struct portio_sysfs_entry portio_size_attribute =
184 	__ATTR(size, S_IRUGO, portio_size_show, NULL);
185 static struct portio_sysfs_entry portio_porttype_attribute =
186 	__ATTR(porttype, S_IRUGO, portio_porttype_show, NULL);
187 
188 static struct attribute *portio_attrs[] = {
189 	&portio_name_attribute.attr,
190 	&portio_start_attribute.attr,
191 	&portio_size_attribute.attr,
192 	&portio_porttype_attribute.attr,
193 	NULL,
194 };
195 
196 static void portio_release(struct kobject *kobj)
197 {
198 	struct uio_portio *portio = to_portio(kobj);
199 	kfree(portio);
200 }
201 
202 static ssize_t portio_type_show(struct kobject *kobj, struct attribute *attr,
203 			     char *buf)
204 {
205 	struct uio_portio *portio = to_portio(kobj);
206 	struct uio_port *port = portio->port;
207 	struct portio_sysfs_entry *entry;
208 
209 	entry = container_of(attr, struct portio_sysfs_entry, attr);
210 
211 	if (!entry->show)
212 		return -EIO;
213 
214 	return entry->show(port, buf);
215 }
216 
217 static const struct sysfs_ops portio_sysfs_ops = {
218 	.show = portio_type_show,
219 };
220 
221 static struct kobj_type portio_attr_type = {
222 	.release	= portio_release,
223 	.sysfs_ops	= &portio_sysfs_ops,
224 	.default_attrs	= portio_attrs,
225 };
226 
227 static ssize_t show_name(struct device *dev,
228 			 struct device_attribute *attr, char *buf)
229 {
230 	struct uio_device *idev = dev_get_drvdata(dev);
231 	return sprintf(buf, "%s\n", idev->info->name);
232 }
233 
234 static ssize_t show_version(struct device *dev,
235 			    struct device_attribute *attr, char *buf)
236 {
237 	struct uio_device *idev = dev_get_drvdata(dev);
238 	return sprintf(buf, "%s\n", idev->info->version);
239 }
240 
241 static ssize_t show_event(struct device *dev,
242 			  struct device_attribute *attr, char *buf)
243 {
244 	struct uio_device *idev = dev_get_drvdata(dev);
245 	return sprintf(buf, "%u\n", (unsigned int)atomic_read(&idev->event));
246 }
247 
248 static struct device_attribute uio_class_attributes[] = {
249 	__ATTR(name, S_IRUGO, show_name, NULL),
250 	__ATTR(version, S_IRUGO, show_version, NULL),
251 	__ATTR(event, S_IRUGO, show_event, NULL),
252 	{}
253 };
254 
255 /* UIO class infrastructure */
256 static struct class uio_class = {
257 	.name = "uio",
258 	.dev_attrs = uio_class_attributes,
259 };
260 
261 /*
262  * device functions
263  */
264 static int uio_dev_add_attributes(struct uio_device *idev)
265 {
266 	int ret;
267 	int mi, pi;
268 	int map_found = 0;
269 	int portio_found = 0;
270 	struct uio_mem *mem;
271 	struct uio_map *map;
272 	struct uio_port *port;
273 	struct uio_portio *portio;
274 
275 	for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
276 		mem = &idev->info->mem[mi];
277 		if (mem->size == 0)
278 			break;
279 		if (!map_found) {
280 			map_found = 1;
281 			idev->map_dir = kobject_create_and_add("maps",
282 							&idev->dev->kobj);
283 			if (!idev->map_dir)
284 				goto err_map;
285 		}
286 		map = kzalloc(sizeof(*map), GFP_KERNEL);
287 		if (!map)
288 			goto err_map;
289 		kobject_init(&map->kobj, &map_attr_type);
290 		map->mem = mem;
291 		mem->map = map;
292 		ret = kobject_add(&map->kobj, idev->map_dir, "map%d", mi);
293 		if (ret)
294 			goto err_map;
295 		ret = kobject_uevent(&map->kobj, KOBJ_ADD);
296 		if (ret)
297 			goto err_map;
298 	}
299 
300 	for (pi = 0; pi < MAX_UIO_PORT_REGIONS; pi++) {
301 		port = &idev->info->port[pi];
302 		if (port->size == 0)
303 			break;
304 		if (!portio_found) {
305 			portio_found = 1;
306 			idev->portio_dir = kobject_create_and_add("portio",
307 							&idev->dev->kobj);
308 			if (!idev->portio_dir)
309 				goto err_portio;
310 		}
311 		portio = kzalloc(sizeof(*portio), GFP_KERNEL);
312 		if (!portio)
313 			goto err_portio;
314 		kobject_init(&portio->kobj, &portio_attr_type);
315 		portio->port = port;
316 		port->portio = portio;
317 		ret = kobject_add(&portio->kobj, idev->portio_dir,
318 							"port%d", pi);
319 		if (ret)
320 			goto err_portio;
321 		ret = kobject_uevent(&portio->kobj, KOBJ_ADD);
322 		if (ret)
323 			goto err_portio;
324 	}
325 
326 	return 0;
327 
328 err_portio:
329 	for (pi--; pi >= 0; pi--) {
330 		port = &idev->info->port[pi];
331 		portio = port->portio;
332 		kobject_put(&portio->kobj);
333 	}
334 	kobject_put(idev->portio_dir);
335 err_map:
336 	for (mi--; mi>=0; mi--) {
337 		mem = &idev->info->mem[mi];
338 		map = mem->map;
339 		kobject_put(&map->kobj);
340 	}
341 	kobject_put(idev->map_dir);
342 	dev_err(idev->dev, "error creating sysfs files (%d)\n", ret);
343 	return ret;
344 }
345 
346 static void uio_dev_del_attributes(struct uio_device *idev)
347 {
348 	int i;
349 	struct uio_mem *mem;
350 	struct uio_port *port;
351 
352 	for (i = 0; i < MAX_UIO_MAPS; i++) {
353 		mem = &idev->info->mem[i];
354 		if (mem->size == 0)
355 			break;
356 		kobject_put(&mem->map->kobj);
357 	}
358 	kobject_put(idev->map_dir);
359 
360 	for (i = 0; i < MAX_UIO_PORT_REGIONS; i++) {
361 		port = &idev->info->port[i];
362 		if (port->size == 0)
363 			break;
364 		kobject_put(&port->portio->kobj);
365 	}
366 	kobject_put(idev->portio_dir);
367 }
368 
369 static int uio_get_minor(struct uio_device *idev)
370 {
371 	int retval = -ENOMEM;
372 	int id;
373 
374 	mutex_lock(&minor_lock);
375 	if (idr_pre_get(&uio_idr, GFP_KERNEL) == 0)
376 		goto exit;
377 
378 	retval = idr_get_new(&uio_idr, idev, &id);
379 	if (retval < 0) {
380 		if (retval == -EAGAIN)
381 			retval = -ENOMEM;
382 		goto exit;
383 	}
384 	if (id < UIO_MAX_DEVICES) {
385 		idev->minor = id;
386 	} else {
387 		dev_err(idev->dev, "too many uio devices\n");
388 		retval = -EINVAL;
389 		idr_remove(&uio_idr, id);
390 	}
391 exit:
392 	mutex_unlock(&minor_lock);
393 	return retval;
394 }
395 
396 static void uio_free_minor(struct uio_device *idev)
397 {
398 	mutex_lock(&minor_lock);
399 	idr_remove(&uio_idr, idev->minor);
400 	mutex_unlock(&minor_lock);
401 }
402 
403 /**
404  * uio_event_notify - trigger an interrupt event
405  * @info: UIO device capabilities
406  */
407 void uio_event_notify(struct uio_info *info)
408 {
409 	struct uio_device *idev = info->uio_dev;
410 
411 	atomic_inc(&idev->event);
412 	wake_up_interruptible(&idev->wait);
413 	kill_fasync(&idev->async_queue, SIGIO, POLL_IN);
414 }
415 EXPORT_SYMBOL_GPL(uio_event_notify);
416 
417 /**
418  * uio_interrupt - hardware interrupt handler
419  * @irq: IRQ number, can be UIO_IRQ_CYCLIC for cyclic timer
420  * @dev_id: Pointer to the devices uio_device structure
421  */
422 static irqreturn_t uio_interrupt(int irq, void *dev_id)
423 {
424 	struct uio_device *idev = (struct uio_device *)dev_id;
425 	irqreturn_t ret = idev->info->handler(irq, idev->info);
426 
427 	if (ret == IRQ_HANDLED)
428 		uio_event_notify(idev->info);
429 
430 	return ret;
431 }
432 
433 struct uio_listener {
434 	struct uio_device *dev;
435 	s32 event_count;
436 };
437 
438 static int uio_open(struct inode *inode, struct file *filep)
439 {
440 	struct uio_device *idev;
441 	struct uio_listener *listener;
442 	int ret = 0;
443 
444 	mutex_lock(&minor_lock);
445 	idev = idr_find(&uio_idr, iminor(inode));
446 	mutex_unlock(&minor_lock);
447 	if (!idev) {
448 		ret = -ENODEV;
449 		goto out;
450 	}
451 
452 	if (!try_module_get(idev->owner)) {
453 		ret = -ENODEV;
454 		goto out;
455 	}
456 
457 	listener = kmalloc(sizeof(*listener), GFP_KERNEL);
458 	if (!listener) {
459 		ret = -ENOMEM;
460 		goto err_alloc_listener;
461 	}
462 
463 	listener->dev = idev;
464 	listener->event_count = atomic_read(&idev->event);
465 	filep->private_data = listener;
466 
467 	if (idev->info->open) {
468 		ret = idev->info->open(idev->info, inode);
469 		if (ret)
470 			goto err_infoopen;
471 	}
472 	return 0;
473 
474 err_infoopen:
475 	kfree(listener);
476 
477 err_alloc_listener:
478 	module_put(idev->owner);
479 
480 out:
481 	return ret;
482 }
483 
484 static int uio_fasync(int fd, struct file *filep, int on)
485 {
486 	struct uio_listener *listener = filep->private_data;
487 	struct uio_device *idev = listener->dev;
488 
489 	return fasync_helper(fd, filep, on, &idev->async_queue);
490 }
491 
492 static int uio_release(struct inode *inode, struct file *filep)
493 {
494 	int ret = 0;
495 	struct uio_listener *listener = filep->private_data;
496 	struct uio_device *idev = listener->dev;
497 
498 	if (idev->info->release)
499 		ret = idev->info->release(idev->info, inode);
500 
501 	module_put(idev->owner);
502 	kfree(listener);
503 	return ret;
504 }
505 
506 static unsigned int uio_poll(struct file *filep, poll_table *wait)
507 {
508 	struct uio_listener *listener = filep->private_data;
509 	struct uio_device *idev = listener->dev;
510 
511 	if (!idev->info->irq)
512 		return -EIO;
513 
514 	poll_wait(filep, &idev->wait, wait);
515 	if (listener->event_count != atomic_read(&idev->event))
516 		return POLLIN | POLLRDNORM;
517 	return 0;
518 }
519 
520 static ssize_t uio_read(struct file *filep, char __user *buf,
521 			size_t count, loff_t *ppos)
522 {
523 	struct uio_listener *listener = filep->private_data;
524 	struct uio_device *idev = listener->dev;
525 	DECLARE_WAITQUEUE(wait, current);
526 	ssize_t retval;
527 	s32 event_count;
528 
529 	if (!idev->info->irq)
530 		return -EIO;
531 
532 	if (count != sizeof(s32))
533 		return -EINVAL;
534 
535 	add_wait_queue(&idev->wait, &wait);
536 
537 	do {
538 		set_current_state(TASK_INTERRUPTIBLE);
539 
540 		event_count = atomic_read(&idev->event);
541 		if (event_count != listener->event_count) {
542 			if (copy_to_user(buf, &event_count, count))
543 				retval = -EFAULT;
544 			else {
545 				listener->event_count = event_count;
546 				retval = count;
547 			}
548 			break;
549 		}
550 
551 		if (filep->f_flags & O_NONBLOCK) {
552 			retval = -EAGAIN;
553 			break;
554 		}
555 
556 		if (signal_pending(current)) {
557 			retval = -ERESTARTSYS;
558 			break;
559 		}
560 		schedule();
561 	} while (1);
562 
563 	__set_current_state(TASK_RUNNING);
564 	remove_wait_queue(&idev->wait, &wait);
565 
566 	return retval;
567 }
568 
569 static ssize_t uio_write(struct file *filep, const char __user *buf,
570 			size_t count, loff_t *ppos)
571 {
572 	struct uio_listener *listener = filep->private_data;
573 	struct uio_device *idev = listener->dev;
574 	ssize_t retval;
575 	s32 irq_on;
576 
577 	if (!idev->info->irq)
578 		return -EIO;
579 
580 	if (count != sizeof(s32))
581 		return -EINVAL;
582 
583 	if (!idev->info->irqcontrol)
584 		return -ENOSYS;
585 
586 	if (copy_from_user(&irq_on, buf, count))
587 		return -EFAULT;
588 
589 	retval = idev->info->irqcontrol(idev->info, irq_on);
590 
591 	return retval ? retval : sizeof(s32);
592 }
593 
594 static int uio_find_mem_index(struct vm_area_struct *vma)
595 {
596 	struct uio_device *idev = vma->vm_private_data;
597 
598 	if (vma->vm_pgoff < MAX_UIO_MAPS) {
599 		if (idev->info->mem[vma->vm_pgoff].size == 0)
600 			return -1;
601 		return (int)vma->vm_pgoff;
602 	}
603 	return -1;
604 }
605 
606 static void uio_vma_open(struct vm_area_struct *vma)
607 {
608 	struct uio_device *idev = vma->vm_private_data;
609 	idev->vma_count++;
610 }
611 
612 static void uio_vma_close(struct vm_area_struct *vma)
613 {
614 	struct uio_device *idev = vma->vm_private_data;
615 	idev->vma_count--;
616 }
617 
618 static int uio_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
619 {
620 	struct uio_device *idev = vma->vm_private_data;
621 	struct page *page;
622 	unsigned long offset;
623 
624 	int mi = uio_find_mem_index(vma);
625 	if (mi < 0)
626 		return VM_FAULT_SIGBUS;
627 
628 	/*
629 	 * We need to subtract mi because userspace uses offset = N*PAGE_SIZE
630 	 * to use mem[N].
631 	 */
632 	offset = (vmf->pgoff - mi) << PAGE_SHIFT;
633 
634 	if (idev->info->mem[mi].memtype == UIO_MEM_LOGICAL)
635 		page = virt_to_page(idev->info->mem[mi].addr + offset);
636 	else
637 		page = vmalloc_to_page((void *)(unsigned long)idev->info->mem[mi].addr + offset);
638 	get_page(page);
639 	vmf->page = page;
640 	return 0;
641 }
642 
643 static const struct vm_operations_struct uio_vm_ops = {
644 	.open = uio_vma_open,
645 	.close = uio_vma_close,
646 	.fault = uio_vma_fault,
647 };
648 
649 static int uio_mmap_physical(struct vm_area_struct *vma)
650 {
651 	struct uio_device *idev = vma->vm_private_data;
652 	int mi = uio_find_mem_index(vma);
653 	if (mi < 0)
654 		return -EINVAL;
655 
656 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
657 
658 	return remap_pfn_range(vma,
659 			       vma->vm_start,
660 			       idev->info->mem[mi].addr >> PAGE_SHIFT,
661 			       vma->vm_end - vma->vm_start,
662 			       vma->vm_page_prot);
663 }
664 
665 static int uio_mmap_logical(struct vm_area_struct *vma)
666 {
667 	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
668 	vma->vm_ops = &uio_vm_ops;
669 	uio_vma_open(vma);
670 	return 0;
671 }
672 
673 static int uio_mmap(struct file *filep, struct vm_area_struct *vma)
674 {
675 	struct uio_listener *listener = filep->private_data;
676 	struct uio_device *idev = listener->dev;
677 	int mi;
678 	unsigned long requested_pages, actual_pages;
679 	int ret = 0;
680 
681 	if (vma->vm_end < vma->vm_start)
682 		return -EINVAL;
683 
684 	vma->vm_private_data = idev;
685 
686 	mi = uio_find_mem_index(vma);
687 	if (mi < 0)
688 		return -EINVAL;
689 
690 	requested_pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
691 	actual_pages = ((idev->info->mem[mi].addr & ~PAGE_MASK)
692 			+ idev->info->mem[mi].size + PAGE_SIZE -1) >> PAGE_SHIFT;
693 	if (requested_pages > actual_pages)
694 		return -EINVAL;
695 
696 	if (idev->info->mmap) {
697 		ret = idev->info->mmap(idev->info, vma);
698 		return ret;
699 	}
700 
701 	switch (idev->info->mem[mi].memtype) {
702 		case UIO_MEM_PHYS:
703 			return uio_mmap_physical(vma);
704 		case UIO_MEM_LOGICAL:
705 		case UIO_MEM_VIRTUAL:
706 			return uio_mmap_logical(vma);
707 		default:
708 			return -EINVAL;
709 	}
710 }
711 
712 static const struct file_operations uio_fops = {
713 	.owner		= THIS_MODULE,
714 	.open		= uio_open,
715 	.release	= uio_release,
716 	.read		= uio_read,
717 	.write		= uio_write,
718 	.mmap		= uio_mmap,
719 	.poll		= uio_poll,
720 	.fasync		= uio_fasync,
721 	.llseek		= noop_llseek,
722 };
723 
724 static int uio_major_init(void)
725 {
726 	static const char name[] = "uio";
727 	struct cdev *cdev = NULL;
728 	dev_t uio_dev = 0;
729 	int result;
730 
731 	result = alloc_chrdev_region(&uio_dev, 0, UIO_MAX_DEVICES, name);
732 	if (result)
733 		goto out;
734 
735 	result = -ENOMEM;
736 	cdev = cdev_alloc();
737 	if (!cdev)
738 		goto out_unregister;
739 
740 	cdev->owner = THIS_MODULE;
741 	cdev->ops = &uio_fops;
742 	kobject_set_name(&cdev->kobj, "%s", name);
743 
744 	result = cdev_add(cdev, uio_dev, UIO_MAX_DEVICES);
745 	if (result)
746 		goto out_put;
747 
748 	uio_major = MAJOR(uio_dev);
749 	uio_cdev = cdev;
750 	return 0;
751 out_put:
752 	kobject_put(&cdev->kobj);
753 out_unregister:
754 	unregister_chrdev_region(uio_dev, UIO_MAX_DEVICES);
755 out:
756 	return result;
757 }
758 
759 static void uio_major_cleanup(void)
760 {
761 	unregister_chrdev_region(MKDEV(uio_major, 0), UIO_MAX_DEVICES);
762 	cdev_del(uio_cdev);
763 }
764 
765 static int init_uio_class(void)
766 {
767 	int ret;
768 
769 	/* This is the first time in here, set everything up properly */
770 	ret = uio_major_init();
771 	if (ret)
772 		goto exit;
773 
774 	ret = class_register(&uio_class);
775 	if (ret) {
776 		printk(KERN_ERR "class_register failed for uio\n");
777 		goto err_class_register;
778 	}
779 	return 0;
780 
781 err_class_register:
782 	uio_major_cleanup();
783 exit:
784 	return ret;
785 }
786 
787 static void release_uio_class(void)
788 {
789 	class_unregister(&uio_class);
790 	uio_major_cleanup();
791 }
792 
793 /**
794  * uio_register_device - register a new userspace IO device
795  * @owner:	module that creates the new device
796  * @parent:	parent device
797  * @info:	UIO device capabilities
798  *
799  * returns zero on success or a negative error code.
800  */
801 int __uio_register_device(struct module *owner,
802 			  struct device *parent,
803 			  struct uio_info *info)
804 {
805 	struct uio_device *idev;
806 	int ret = 0;
807 
808 	if (!parent || !info || !info->name || !info->version)
809 		return -EINVAL;
810 
811 	info->uio_dev = NULL;
812 
813 	idev = kzalloc(sizeof(*idev), GFP_KERNEL);
814 	if (!idev) {
815 		ret = -ENOMEM;
816 		goto err_kzalloc;
817 	}
818 
819 	idev->owner = owner;
820 	idev->info = info;
821 	init_waitqueue_head(&idev->wait);
822 	atomic_set(&idev->event, 0);
823 
824 	ret = uio_get_minor(idev);
825 	if (ret)
826 		goto err_get_minor;
827 
828 	idev->dev = device_create(&uio_class, parent,
829 				  MKDEV(uio_major, idev->minor), idev,
830 				  "uio%d", idev->minor);
831 	if (IS_ERR(idev->dev)) {
832 		printk(KERN_ERR "UIO: device register failed\n");
833 		ret = PTR_ERR(idev->dev);
834 		goto err_device_create;
835 	}
836 
837 	ret = uio_dev_add_attributes(idev);
838 	if (ret)
839 		goto err_uio_dev_add_attributes;
840 
841 	info->uio_dev = idev;
842 
843 	if (info->irq && (info->irq != UIO_IRQ_CUSTOM)) {
844 		ret = request_irq(info->irq, uio_interrupt,
845 				  info->irq_flags, info->name, idev);
846 		if (ret)
847 			goto err_request_irq;
848 	}
849 
850 	return 0;
851 
852 err_request_irq:
853 	uio_dev_del_attributes(idev);
854 err_uio_dev_add_attributes:
855 	device_destroy(&uio_class, MKDEV(uio_major, idev->minor));
856 err_device_create:
857 	uio_free_minor(idev);
858 err_get_minor:
859 	kfree(idev);
860 err_kzalloc:
861 	return ret;
862 }
863 EXPORT_SYMBOL_GPL(__uio_register_device);
864 
865 /**
866  * uio_unregister_device - unregister a industrial IO device
867  * @info:	UIO device capabilities
868  *
869  */
870 void uio_unregister_device(struct uio_info *info)
871 {
872 	struct uio_device *idev;
873 
874 	if (!info || !info->uio_dev)
875 		return;
876 
877 	idev = info->uio_dev;
878 
879 	uio_free_minor(idev);
880 
881 	if (info->irq && (info->irq != UIO_IRQ_CUSTOM))
882 		free_irq(info->irq, idev);
883 
884 	uio_dev_del_attributes(idev);
885 
886 	device_destroy(&uio_class, MKDEV(uio_major, idev->minor));
887 	kfree(idev);
888 
889 	return;
890 }
891 EXPORT_SYMBOL_GPL(uio_unregister_device);
892 
893 static int __init uio_init(void)
894 {
895 	return init_uio_class();
896 }
897 
898 static void __exit uio_exit(void)
899 {
900 	release_uio_class();
901 }
902 
903 module_init(uio_init)
904 module_exit(uio_exit)
905 MODULE_LICENSE("GPL v2");
906