xref: /openbmc/linux/drivers/uio/uio.c (revision 3932b9ca) 
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 	struct uio_info		*info;
39 	struct kobject		*map_dir;
40 	struct kobject		*portio_dir;
41 };
42 
43 static int uio_major;
44 static struct cdev *uio_cdev;
45 static DEFINE_IDR(uio_idr);
46 static const struct file_operations uio_fops;
47 
48 /* Protect idr accesses */
49 static DEFINE_MUTEX(minor_lock);
50 
51 /*
52  * attributes
53  */
54 
55 struct uio_map {
56 	struct kobject kobj;
57 	struct uio_mem *mem;
58 };
59 #define to_map(map) container_of(map, struct uio_map, kobj)
60 
61 static ssize_t map_name_show(struct uio_mem *mem, char *buf)
62 {
63 	if (unlikely(!mem->name))
64 		mem->name = "";
65 
66 	return sprintf(buf, "%s\n", mem->name);
67 }
68 
69 static ssize_t map_addr_show(struct uio_mem *mem, char *buf)
70 {
71 	return sprintf(buf, "0x%llx\n", (unsigned long long)mem->addr);
72 }
73 
74 static ssize_t map_size_show(struct uio_mem *mem, char *buf)
75 {
76 	return sprintf(buf, "0x%lx\n", mem->size);
77 }
78 
79 static ssize_t map_offset_show(struct uio_mem *mem, char *buf)
80 {
81 	return sprintf(buf, "0x%llx\n", (unsigned long long)mem->addr & ~PAGE_MASK);
82 }
83 
84 struct map_sysfs_entry {
85 	struct attribute attr;
86 	ssize_t (*show)(struct uio_mem *, char *);
87 	ssize_t (*store)(struct uio_mem *, const char *, size_t);
88 };
89 
90 static struct map_sysfs_entry name_attribute =
91 	__ATTR(name, S_IRUGO, map_name_show, NULL);
92 static struct map_sysfs_entry addr_attribute =
93 	__ATTR(addr, S_IRUGO, map_addr_show, NULL);
94 static struct map_sysfs_entry size_attribute =
95 	__ATTR(size, S_IRUGO, map_size_show, NULL);
96 static struct map_sysfs_entry offset_attribute =
97 	__ATTR(offset, S_IRUGO, map_offset_show, NULL);
98 
99 static struct attribute *attrs[] = {
100 	&name_attribute.attr,
101 	&addr_attribute.attr,
102 	&size_attribute.attr,
103 	&offset_attribute.attr,
104 	NULL,	/* need to NULL terminate the list of attributes */
105 };
106 
107 static void map_release(struct kobject *kobj)
108 {
109 	struct uio_map *map = to_map(kobj);
110 	kfree(map);
111 }
112 
113 static ssize_t map_type_show(struct kobject *kobj, struct attribute *attr,
114 			     char *buf)
115 {
116 	struct uio_map *map = to_map(kobj);
117 	struct uio_mem *mem = map->mem;
118 	struct map_sysfs_entry *entry;
119 
120 	entry = container_of(attr, struct map_sysfs_entry, attr);
121 
122 	if (!entry->show)
123 		return -EIO;
124 
125 	return entry->show(mem, buf);
126 }
127 
128 static const struct sysfs_ops map_sysfs_ops = {
129 	.show = map_type_show,
130 };
131 
132 static struct kobj_type map_attr_type = {
133 	.release	= map_release,
134 	.sysfs_ops	= &map_sysfs_ops,
135 	.default_attrs	= attrs,
136 };
137 
138 struct uio_portio {
139 	struct kobject kobj;
140 	struct uio_port *port;
141 };
142 #define to_portio(portio) container_of(portio, struct uio_portio, kobj)
143 
144 static ssize_t portio_name_show(struct uio_port *port, char *buf)
145 {
146 	if (unlikely(!port->name))
147 		port->name = "";
148 
149 	return sprintf(buf, "%s\n", port->name);
150 }
151 
152 static ssize_t portio_start_show(struct uio_port *port, char *buf)
153 {
154 	return sprintf(buf, "0x%lx\n", port->start);
155 }
156 
157 static ssize_t portio_size_show(struct uio_port *port, char *buf)
158 {
159 	return sprintf(buf, "0x%lx\n", port->size);
160 }
161 
162 static ssize_t portio_porttype_show(struct uio_port *port, char *buf)
163 {
164 	const char *porttypes[] = {"none", "x86", "gpio", "other"};
165 
166 	if ((port->porttype < 0) || (port->porttype > UIO_PORT_OTHER))
167 		return -EINVAL;
168 
169 	return sprintf(buf, "port_%s\n", porttypes[port->porttype]);
170 }
171 
172 struct portio_sysfs_entry {
173 	struct attribute attr;
174 	ssize_t (*show)(struct uio_port *, char *);
175 	ssize_t (*store)(struct uio_port *, const char *, size_t);
176 };
177 
178 static struct portio_sysfs_entry portio_name_attribute =
179 	__ATTR(name, S_IRUGO, portio_name_show, NULL);
180 static struct portio_sysfs_entry portio_start_attribute =
181 	__ATTR(start, S_IRUGO, portio_start_show, NULL);
182 static struct portio_sysfs_entry portio_size_attribute =
183 	__ATTR(size, S_IRUGO, portio_size_show, NULL);
184 static struct portio_sysfs_entry portio_porttype_attribute =
185 	__ATTR(porttype, S_IRUGO, portio_porttype_show, NULL);
186 
187 static struct attribute *portio_attrs[] = {
188 	&portio_name_attribute.attr,
189 	&portio_start_attribute.attr,
190 	&portio_size_attribute.attr,
191 	&portio_porttype_attribute.attr,
192 	NULL,
193 };
194 
195 static void portio_release(struct kobject *kobj)
196 {
197 	struct uio_portio *portio = to_portio(kobj);
198 	kfree(portio);
199 }
200 
201 static ssize_t portio_type_show(struct kobject *kobj, struct attribute *attr,
202 			     char *buf)
203 {
204 	struct uio_portio *portio = to_portio(kobj);
205 	struct uio_port *port = portio->port;
206 	struct portio_sysfs_entry *entry;
207 
208 	entry = container_of(attr, struct portio_sysfs_entry, attr);
209 
210 	if (!entry->show)
211 		return -EIO;
212 
213 	return entry->show(port, buf);
214 }
215 
216 static const struct sysfs_ops portio_sysfs_ops = {
217 	.show = portio_type_show,
218 };
219 
220 static struct kobj_type portio_attr_type = {
221 	.release	= portio_release,
222 	.sysfs_ops	= &portio_sysfs_ops,
223 	.default_attrs	= portio_attrs,
224 };
225 
226 static ssize_t name_show(struct device *dev,
227 			 struct device_attribute *attr, char *buf)
228 {
229 	struct uio_device *idev = dev_get_drvdata(dev);
230 	return sprintf(buf, "%s\n", idev->info->name);
231 }
232 static DEVICE_ATTR_RO(name);
233 
234 static ssize_t version_show(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 static DEVICE_ATTR_RO(version);
241 
242 static ssize_t event_show(struct device *dev,
243 			  struct device_attribute *attr, char *buf)
244 {
245 	struct uio_device *idev = dev_get_drvdata(dev);
246 	return sprintf(buf, "%u\n", (unsigned int)atomic_read(&idev->event));
247 }
248 static DEVICE_ATTR_RO(event);
249 
250 static struct attribute *uio_attrs[] = {
251 	&dev_attr_name.attr,
252 	&dev_attr_version.attr,
253 	&dev_attr_event.attr,
254 	NULL,
255 };
256 ATTRIBUTE_GROUPS(uio);
257 
258 /* UIO class infrastructure */
259 static struct class uio_class = {
260 	.name = "uio",
261 	.dev_groups = uio_groups,
262 };
263 
264 /*
265  * device functions
266  */
267 static int uio_dev_add_attributes(struct uio_device *idev)
268 {
269 	int ret;
270 	int mi, pi;
271 	int map_found = 0;
272 	int portio_found = 0;
273 	struct uio_mem *mem;
274 	struct uio_map *map;
275 	struct uio_port *port;
276 	struct uio_portio *portio;
277 
278 	for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
279 		mem = &idev->info->mem[mi];
280 		if (mem->size == 0)
281 			break;
282 		if (!map_found) {
283 			map_found = 1;
284 			idev->map_dir = kobject_create_and_add("maps",
285 							&idev->dev->kobj);
286 			if (!idev->map_dir)
287 				goto err_map;
288 		}
289 		map = kzalloc(sizeof(*map), GFP_KERNEL);
290 		if (!map)
291 			goto err_map_kobj;
292 		kobject_init(&map->kobj, &map_attr_type);
293 		map->mem = mem;
294 		mem->map = map;
295 		ret = kobject_add(&map->kobj, idev->map_dir, "map%d", mi);
296 		if (ret)
297 			goto err_map_kobj;
298 		ret = kobject_uevent(&map->kobj, KOBJ_ADD);
299 		if (ret)
300 			goto err_map;
301 	}
302 
303 	for (pi = 0; pi < MAX_UIO_PORT_REGIONS; pi++) {
304 		port = &idev->info->port[pi];
305 		if (port->size == 0)
306 			break;
307 		if (!portio_found) {
308 			portio_found = 1;
309 			idev->portio_dir = kobject_create_and_add("portio",
310 							&idev->dev->kobj);
311 			if (!idev->portio_dir)
312 				goto err_portio;
313 		}
314 		portio = kzalloc(sizeof(*portio), GFP_KERNEL);
315 		if (!portio)
316 			goto err_portio_kobj;
317 		kobject_init(&portio->kobj, &portio_attr_type);
318 		portio->port = port;
319 		port->portio = portio;
320 		ret = kobject_add(&portio->kobj, idev->portio_dir,
321 							"port%d", pi);
322 		if (ret)
323 			goto err_portio_kobj;
324 		ret = kobject_uevent(&portio->kobj, KOBJ_ADD);
325 		if (ret)
326 			goto err_portio;
327 	}
328 
329 	return 0;
330 
331 err_portio:
332 	pi--;
333 err_portio_kobj:
334 	for (; pi >= 0; pi--) {
335 		port = &idev->info->port[pi];
336 		portio = port->portio;
337 		kobject_put(&portio->kobj);
338 	}
339 	kobject_put(idev->portio_dir);
340 err_map:
341 	mi--;
342 err_map_kobj:
343 	for (; mi >= 0; mi--) {
344 		mem = &idev->info->mem[mi];
345 		map = mem->map;
346 		kobject_put(&map->kobj);
347 	}
348 	kobject_put(idev->map_dir);
349 	dev_err(idev->dev, "error creating sysfs files (%d)\n", ret);
350 	return ret;
351 }
352 
353 static void uio_dev_del_attributes(struct uio_device *idev)
354 {
355 	int i;
356 	struct uio_mem *mem;
357 	struct uio_port *port;
358 
359 	for (i = 0; i < MAX_UIO_MAPS; i++) {
360 		mem = &idev->info->mem[i];
361 		if (mem->size == 0)
362 			break;
363 		kobject_put(&mem->map->kobj);
364 	}
365 	kobject_put(idev->map_dir);
366 
367 	for (i = 0; i < MAX_UIO_PORT_REGIONS; i++) {
368 		port = &idev->info->port[i];
369 		if (port->size == 0)
370 			break;
371 		kobject_put(&port->portio->kobj);
372 	}
373 	kobject_put(idev->portio_dir);
374 }
375 
376 static int uio_get_minor(struct uio_device *idev)
377 {
378 	int retval = -ENOMEM;
379 
380 	mutex_lock(&minor_lock);
381 	retval = idr_alloc(&uio_idr, idev, 0, UIO_MAX_DEVICES, GFP_KERNEL);
382 	if (retval >= 0) {
383 		idev->minor = retval;
384 		retval = 0;
385 	} else if (retval == -ENOSPC) {
386 		dev_err(idev->dev, "too many uio devices\n");
387 		retval = -EINVAL;
388 	}
389 	mutex_unlock(&minor_lock);
390 	return retval;
391 }
392 
393 static void uio_free_minor(struct uio_device *idev)
394 {
395 	mutex_lock(&minor_lock);
396 	idr_remove(&uio_idr, idev->minor);
397 	mutex_unlock(&minor_lock);
398 }
399 
400 /**
401  * uio_event_notify - trigger an interrupt event
402  * @info: UIO device capabilities
403  */
404 void uio_event_notify(struct uio_info *info)
405 {
406 	struct uio_device *idev = info->uio_dev;
407 
408 	atomic_inc(&idev->event);
409 	wake_up_interruptible(&idev->wait);
410 	kill_fasync(&idev->async_queue, SIGIO, POLL_IN);
411 }
412 EXPORT_SYMBOL_GPL(uio_event_notify);
413 
414 /**
415  * uio_interrupt - hardware interrupt handler
416  * @irq: IRQ number, can be UIO_IRQ_CYCLIC for cyclic timer
417  * @dev_id: Pointer to the devices uio_device structure
418  */
419 static irqreturn_t uio_interrupt(int irq, void *dev_id)
420 {
421 	struct uio_device *idev = (struct uio_device *)dev_id;
422 	irqreturn_t ret = idev->info->handler(irq, idev->info);
423 
424 	if (ret == IRQ_HANDLED)
425 		uio_event_notify(idev->info);
426 
427 	return ret;
428 }
429 
430 struct uio_listener {
431 	struct uio_device *dev;
432 	s32 event_count;
433 };
434 
435 static int uio_open(struct inode *inode, struct file *filep)
436 {
437 	struct uio_device *idev;
438 	struct uio_listener *listener;
439 	int ret = 0;
440 
441 	mutex_lock(&minor_lock);
442 	idev = idr_find(&uio_idr, iminor(inode));
443 	mutex_unlock(&minor_lock);
444 	if (!idev) {
445 		ret = -ENODEV;
446 		goto out;
447 	}
448 
449 	if (!try_module_get(idev->owner)) {
450 		ret = -ENODEV;
451 		goto out;
452 	}
453 
454 	listener = kmalloc(sizeof(*listener), GFP_KERNEL);
455 	if (!listener) {
456 		ret = -ENOMEM;
457 		goto err_alloc_listener;
458 	}
459 
460 	listener->dev = idev;
461 	listener->event_count = atomic_read(&idev->event);
462 	filep->private_data = listener;
463 
464 	if (idev->info->open) {
465 		ret = idev->info->open(idev->info, inode);
466 		if (ret)
467 			goto err_infoopen;
468 	}
469 	return 0;
470 
471 err_infoopen:
472 	kfree(listener);
473 
474 err_alloc_listener:
475 	module_put(idev->owner);
476 
477 out:
478 	return ret;
479 }
480 
481 static int uio_fasync(int fd, struct file *filep, int on)
482 {
483 	struct uio_listener *listener = filep->private_data;
484 	struct uio_device *idev = listener->dev;
485 
486 	return fasync_helper(fd, filep, on, &idev->async_queue);
487 }
488 
489 static int uio_release(struct inode *inode, struct file *filep)
490 {
491 	int ret = 0;
492 	struct uio_listener *listener = filep->private_data;
493 	struct uio_device *idev = listener->dev;
494 
495 	if (idev->info->release)
496 		ret = idev->info->release(idev->info, inode);
497 
498 	module_put(idev->owner);
499 	kfree(listener);
500 	return ret;
501 }
502 
503 static unsigned int uio_poll(struct file *filep, poll_table *wait)
504 {
505 	struct uio_listener *listener = filep->private_data;
506 	struct uio_device *idev = listener->dev;
507 
508 	if (!idev->info->irq)
509 		return -EIO;
510 
511 	poll_wait(filep, &idev->wait, wait);
512 	if (listener->event_count != atomic_read(&idev->event))
513 		return POLLIN | POLLRDNORM;
514 	return 0;
515 }
516 
517 static ssize_t uio_read(struct file *filep, char __user *buf,
518 			size_t count, loff_t *ppos)
519 {
520 	struct uio_listener *listener = filep->private_data;
521 	struct uio_device *idev = listener->dev;
522 	DECLARE_WAITQUEUE(wait, current);
523 	ssize_t retval;
524 	s32 event_count;
525 
526 	if (!idev->info->irq)
527 		return -EIO;
528 
529 	if (count != sizeof(s32))
530 		return -EINVAL;
531 
532 	add_wait_queue(&idev->wait, &wait);
533 
534 	do {
535 		set_current_state(TASK_INTERRUPTIBLE);
536 
537 		event_count = atomic_read(&idev->event);
538 		if (event_count != listener->event_count) {
539 			if (copy_to_user(buf, &event_count, count))
540 				retval = -EFAULT;
541 			else {
542 				listener->event_count = event_count;
543 				retval = count;
544 			}
545 			break;
546 		}
547 
548 		if (filep->f_flags & O_NONBLOCK) {
549 			retval = -EAGAIN;
550 			break;
551 		}
552 
553 		if (signal_pending(current)) {
554 			retval = -ERESTARTSYS;
555 			break;
556 		}
557 		schedule();
558 	} while (1);
559 
560 	__set_current_state(TASK_RUNNING);
561 	remove_wait_queue(&idev->wait, &wait);
562 
563 	return retval;
564 }
565 
566 static ssize_t uio_write(struct file *filep, const char __user *buf,
567 			size_t count, loff_t *ppos)
568 {
569 	struct uio_listener *listener = filep->private_data;
570 	struct uio_device *idev = listener->dev;
571 	ssize_t retval;
572 	s32 irq_on;
573 
574 	if (!idev->info->irq)
575 		return -EIO;
576 
577 	if (count != sizeof(s32))
578 		return -EINVAL;
579 
580 	if (!idev->info->irqcontrol)
581 		return -ENOSYS;
582 
583 	if (copy_from_user(&irq_on, buf, count))
584 		return -EFAULT;
585 
586 	retval = idev->info->irqcontrol(idev->info, irq_on);
587 
588 	return retval ? retval : sizeof(s32);
589 }
590 
591 static int uio_find_mem_index(struct vm_area_struct *vma)
592 {
593 	struct uio_device *idev = vma->vm_private_data;
594 
595 	if (vma->vm_pgoff < MAX_UIO_MAPS) {
596 		if (idev->info->mem[vma->vm_pgoff].size == 0)
597 			return -1;
598 		return (int)vma->vm_pgoff;
599 	}
600 	return -1;
601 }
602 
603 static int uio_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
604 {
605 	struct uio_device *idev = vma->vm_private_data;
606 	struct page *page;
607 	unsigned long offset;
608 	void *addr;
609 
610 	int mi = uio_find_mem_index(vma);
611 	if (mi < 0)
612 		return VM_FAULT_SIGBUS;
613 
614 	/*
615 	 * We need to subtract mi because userspace uses offset = N*PAGE_SIZE
616 	 * to use mem[N].
617 	 */
618 	offset = (vmf->pgoff - mi) << PAGE_SHIFT;
619 
620 	addr = (void *)(unsigned long)idev->info->mem[mi].addr + offset;
621 	if (idev->info->mem[mi].memtype == UIO_MEM_LOGICAL)
622 		page = virt_to_page(addr);
623 	else
624 		page = vmalloc_to_page(addr);
625 	get_page(page);
626 	vmf->page = page;
627 	return 0;
628 }
629 
630 static const struct vm_operations_struct uio_logical_vm_ops = {
631 	.fault = uio_vma_fault,
632 };
633 
634 static int uio_mmap_logical(struct vm_area_struct *vma)
635 {
636 	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
637 	vma->vm_ops = &uio_logical_vm_ops;
638 	return 0;
639 }
640 
641 static const struct vm_operations_struct uio_physical_vm_ops = {
642 #ifdef CONFIG_HAVE_IOREMAP_PROT
643 	.access = generic_access_phys,
644 #endif
645 };
646 
647 static int uio_mmap_physical(struct vm_area_struct *vma)
648 {
649 	struct uio_device *idev = vma->vm_private_data;
650 	int mi = uio_find_mem_index(vma);
651 	struct uio_mem *mem;
652 	if (mi < 0)
653 		return -EINVAL;
654 	mem = idev->info->mem + mi;
655 
656 	if (mem->addr & ~PAGE_MASK)
657 		return -ENODEV;
658 	if (vma->vm_end - vma->vm_start > mem->size)
659 		return -EINVAL;
660 
661 	vma->vm_ops = &uio_physical_vm_ops;
662 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
663 
664 	/*
665 	 * We cannot use the vm_iomap_memory() helper here,
666 	 * because vma->vm_pgoff is the map index we looked
667 	 * up above in uio_find_mem_index(), rather than an
668 	 * actual page offset into the mmap.
669 	 *
670 	 * So we just do the physical mmap without a page
671 	 * offset.
672 	 */
673 	return remap_pfn_range(vma,
674 			       vma->vm_start,
675 			       mem->addr >> PAGE_SHIFT,
676 			       vma->vm_end - vma->vm_start,
677 			       vma->vm_page_prot);
678 }
679 
680 static int uio_mmap(struct file *filep, struct vm_area_struct *vma)
681 {
682 	struct uio_listener *listener = filep->private_data;
683 	struct uio_device *idev = listener->dev;
684 	int mi;
685 	unsigned long requested_pages, actual_pages;
686 	int ret = 0;
687 
688 	if (vma->vm_end < vma->vm_start)
689 		return -EINVAL;
690 
691 	vma->vm_private_data = idev;
692 
693 	mi = uio_find_mem_index(vma);
694 	if (mi < 0)
695 		return -EINVAL;
696 
697 	requested_pages = vma_pages(vma);
698 	actual_pages = ((idev->info->mem[mi].addr & ~PAGE_MASK)
699 			+ idev->info->mem[mi].size + PAGE_SIZE -1) >> PAGE_SHIFT;
700 	if (requested_pages > actual_pages)
701 		return -EINVAL;
702 
703 	if (idev->info->mmap) {
704 		ret = idev->info->mmap(idev->info, vma);
705 		return ret;
706 	}
707 
708 	switch (idev->info->mem[mi].memtype) {
709 		case UIO_MEM_PHYS:
710 			return uio_mmap_physical(vma);
711 		case UIO_MEM_LOGICAL:
712 		case UIO_MEM_VIRTUAL:
713 			return uio_mmap_logical(vma);
714 		default:
715 			return -EINVAL;
716 	}
717 }
718 
719 static const struct file_operations uio_fops = {
720 	.owner		= THIS_MODULE,
721 	.open		= uio_open,
722 	.release	= uio_release,
723 	.read		= uio_read,
724 	.write		= uio_write,
725 	.mmap		= uio_mmap,
726 	.poll		= uio_poll,
727 	.fasync		= uio_fasync,
728 	.llseek		= noop_llseek,
729 };
730 
731 static int uio_major_init(void)
732 {
733 	static const char name[] = "uio";
734 	struct cdev *cdev = NULL;
735 	dev_t uio_dev = 0;
736 	int result;
737 
738 	result = alloc_chrdev_region(&uio_dev, 0, UIO_MAX_DEVICES, name);
739 	if (result)
740 		goto out;
741 
742 	result = -ENOMEM;
743 	cdev = cdev_alloc();
744 	if (!cdev)
745 		goto out_unregister;
746 
747 	cdev->owner = THIS_MODULE;
748 	cdev->ops = &uio_fops;
749 	kobject_set_name(&cdev->kobj, "%s", name);
750 
751 	result = cdev_add(cdev, uio_dev, UIO_MAX_DEVICES);
752 	if (result)
753 		goto out_put;
754 
755 	uio_major = MAJOR(uio_dev);
756 	uio_cdev = cdev;
757 	return 0;
758 out_put:
759 	kobject_put(&cdev->kobj);
760 out_unregister:
761 	unregister_chrdev_region(uio_dev, UIO_MAX_DEVICES);
762 out:
763 	return result;
764 }
765 
766 static void uio_major_cleanup(void)
767 {
768 	unregister_chrdev_region(MKDEV(uio_major, 0), UIO_MAX_DEVICES);
769 	cdev_del(uio_cdev);
770 }
771 
772 static int init_uio_class(void)
773 {
774 	int ret;
775 
776 	/* This is the first time in here, set everything up properly */
777 	ret = uio_major_init();
778 	if (ret)
779 		goto exit;
780 
781 	ret = class_register(&uio_class);
782 	if (ret) {
783 		printk(KERN_ERR "class_register failed for uio\n");
784 		goto err_class_register;
785 	}
786 	return 0;
787 
788 err_class_register:
789 	uio_major_cleanup();
790 exit:
791 	return ret;
792 }
793 
794 static void release_uio_class(void)
795 {
796 	class_unregister(&uio_class);
797 	uio_major_cleanup();
798 }
799 
800 /**
801  * uio_register_device - register a new userspace IO device
802  * @owner:	module that creates the new device
803  * @parent:	parent device
804  * @info:	UIO device capabilities
805  *
806  * returns zero on success or a negative error code.
807  */
808 int __uio_register_device(struct module *owner,
809 			  struct device *parent,
810 			  struct uio_info *info)
811 {
812 	struct uio_device *idev;
813 	int ret = 0;
814 
815 	if (!parent || !info || !info->name || !info->version)
816 		return -EINVAL;
817 
818 	info->uio_dev = NULL;
819 
820 	idev = devm_kzalloc(parent, sizeof(*idev), GFP_KERNEL);
821 	if (!idev) {
822 		return -ENOMEM;
823 	}
824 
825 	idev->owner = owner;
826 	idev->info = info;
827 	init_waitqueue_head(&idev->wait);
828 	atomic_set(&idev->event, 0);
829 
830 	ret = uio_get_minor(idev);
831 	if (ret)
832 		return ret;
833 
834 	idev->dev = device_create(&uio_class, parent,
835 				  MKDEV(uio_major, idev->minor), idev,
836 				  "uio%d", idev->minor);
837 	if (IS_ERR(idev->dev)) {
838 		printk(KERN_ERR "UIO: device register failed\n");
839 		ret = PTR_ERR(idev->dev);
840 		goto err_device_create;
841 	}
842 
843 	ret = uio_dev_add_attributes(idev);
844 	if (ret)
845 		goto err_uio_dev_add_attributes;
846 
847 	info->uio_dev = idev;
848 
849 	if (info->irq && (info->irq != UIO_IRQ_CUSTOM)) {
850 		ret = devm_request_irq(idev->dev, info->irq, uio_interrupt,
851 				  info->irq_flags, info->name, idev);
852 		if (ret)
853 			goto err_request_irq;
854 	}
855 
856 	return 0;
857 
858 err_request_irq:
859 	uio_dev_del_attributes(idev);
860 err_uio_dev_add_attributes:
861 	device_destroy(&uio_class, MKDEV(uio_major, idev->minor));
862 err_device_create:
863 	uio_free_minor(idev);
864 	return ret;
865 }
866 EXPORT_SYMBOL_GPL(__uio_register_device);
867 
868 /**
869  * uio_unregister_device - unregister a industrial IO device
870  * @info:	UIO device capabilities
871  *
872  */
873 void uio_unregister_device(struct uio_info *info)
874 {
875 	struct uio_device *idev;
876 
877 	if (!info || !info->uio_dev)
878 		return;
879 
880 	idev = info->uio_dev;
881 
882 	uio_free_minor(idev);
883 
884 	uio_dev_del_attributes(idev);
885 
886 	device_destroy(&uio_class, MKDEV(uio_major, idev->minor));
887 
888 	return;
889 }
890 EXPORT_SYMBOL_GPL(uio_unregister_device);
891 
892 static int __init uio_init(void)
893 {
894 	return init_uio_class();
895 }
896 
897 static void __exit uio_exit(void)
898 {
899 	release_uio_class();
900 }
901 
902 module_init(uio_init)
903 module_exit(uio_exit)
904 MODULE_LICENSE("GPL v2");
905