xref: /linux/drivers/uio/uio.c (revision 4949009eb8d40a441dcddcd96e101e77d31cf1b2) 
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 static int uio_major;
32 static struct cdev *uio_cdev;
33 static DEFINE_IDR(uio_idr);
34 static const struct file_operations uio_fops;
35 
36 /* Protect idr accesses */
37 static DEFINE_MUTEX(minor_lock);
38 
39 /*
40  * attributes
41  */
42 
43 struct uio_map {
44 	struct kobject kobj;
45 	struct uio_mem *mem;
46 };
47 #define to_map(map) container_of(map, struct uio_map, kobj)
48 
49 static ssize_t map_name_show(struct uio_mem *mem, char *buf)
50 {
51 	if (unlikely(!mem->name))
52 		mem->name = "";
53 
54 	return sprintf(buf, "%s\n", mem->name);
55 }
56 
57 static ssize_t map_addr_show(struct uio_mem *mem, char *buf)
58 {
59 	return sprintf(buf, "%pa\n", &mem->addr);
60 }
61 
62 static ssize_t map_size_show(struct uio_mem *mem, char *buf)
63 {
64 	return sprintf(buf, "%pa\n", &mem->size);
65 }
66 
67 static ssize_t map_offset_show(struct uio_mem *mem, char *buf)
68 {
69 	return sprintf(buf, "0x%llx\n", (unsigned long long)mem->addr & ~PAGE_MASK);
70 }
71 
72 struct map_sysfs_entry {
73 	struct attribute attr;
74 	ssize_t (*show)(struct uio_mem *, char *);
75 	ssize_t (*store)(struct uio_mem *, const char *, size_t);
76 };
77 
78 static struct map_sysfs_entry name_attribute =
79 	__ATTR(name, S_IRUGO, map_name_show, NULL);
80 static struct map_sysfs_entry addr_attribute =
81 	__ATTR(addr, S_IRUGO, map_addr_show, NULL);
82 static struct map_sysfs_entry size_attribute =
83 	__ATTR(size, S_IRUGO, map_size_show, NULL);
84 static struct map_sysfs_entry offset_attribute =
85 	__ATTR(offset, S_IRUGO, map_offset_show, NULL);
86 
87 static struct attribute *attrs[] = {
88 	&name_attribute.attr,
89 	&addr_attribute.attr,
90 	&size_attribute.attr,
91 	&offset_attribute.attr,
92 	NULL,	/* need to NULL terminate the list of attributes */
93 };
94 
95 static void map_release(struct kobject *kobj)
96 {
97 	struct uio_map *map = to_map(kobj);
98 	kfree(map);
99 }
100 
101 static ssize_t map_type_show(struct kobject *kobj, struct attribute *attr,
102 			     char *buf)
103 {
104 	struct uio_map *map = to_map(kobj);
105 	struct uio_mem *mem = map->mem;
106 	struct map_sysfs_entry *entry;
107 
108 	entry = container_of(attr, struct map_sysfs_entry, attr);
109 
110 	if (!entry->show)
111 		return -EIO;
112 
113 	return entry->show(mem, buf);
114 }
115 
116 static const struct sysfs_ops map_sysfs_ops = {
117 	.show = map_type_show,
118 };
119 
120 static struct kobj_type map_attr_type = {
121 	.release	= map_release,
122 	.sysfs_ops	= &map_sysfs_ops,
123 	.default_attrs	= attrs,
124 };
125 
126 struct uio_portio {
127 	struct kobject kobj;
128 	struct uio_port *port;
129 };
130 #define to_portio(portio) container_of(portio, struct uio_portio, kobj)
131 
132 static ssize_t portio_name_show(struct uio_port *port, char *buf)
133 {
134 	if (unlikely(!port->name))
135 		port->name = "";
136 
137 	return sprintf(buf, "%s\n", port->name);
138 }
139 
140 static ssize_t portio_start_show(struct uio_port *port, char *buf)
141 {
142 	return sprintf(buf, "0x%lx\n", port->start);
143 }
144 
145 static ssize_t portio_size_show(struct uio_port *port, char *buf)
146 {
147 	return sprintf(buf, "0x%lx\n", port->size);
148 }
149 
150 static ssize_t portio_porttype_show(struct uio_port *port, char *buf)
151 {
152 	const char *porttypes[] = {"none", "x86", "gpio", "other"};
153 
154 	if ((port->porttype < 0) || (port->porttype > UIO_PORT_OTHER))
155 		return -EINVAL;
156 
157 	return sprintf(buf, "port_%s\n", porttypes[port->porttype]);
158 }
159 
160 struct portio_sysfs_entry {
161 	struct attribute attr;
162 	ssize_t (*show)(struct uio_port *, char *);
163 	ssize_t (*store)(struct uio_port *, const char *, size_t);
164 };
165 
166 static struct portio_sysfs_entry portio_name_attribute =
167 	__ATTR(name, S_IRUGO, portio_name_show, NULL);
168 static struct portio_sysfs_entry portio_start_attribute =
169 	__ATTR(start, S_IRUGO, portio_start_show, NULL);
170 static struct portio_sysfs_entry portio_size_attribute =
171 	__ATTR(size, S_IRUGO, portio_size_show, NULL);
172 static struct portio_sysfs_entry portio_porttype_attribute =
173 	__ATTR(porttype, S_IRUGO, portio_porttype_show, NULL);
174 
175 static struct attribute *portio_attrs[] = {
176 	&portio_name_attribute.attr,
177 	&portio_start_attribute.attr,
178 	&portio_size_attribute.attr,
179 	&portio_porttype_attribute.attr,
180 	NULL,
181 };
182 
183 static void portio_release(struct kobject *kobj)
184 {
185 	struct uio_portio *portio = to_portio(kobj);
186 	kfree(portio);
187 }
188 
189 static ssize_t portio_type_show(struct kobject *kobj, struct attribute *attr,
190 			     char *buf)
191 {
192 	struct uio_portio *portio = to_portio(kobj);
193 	struct uio_port *port = portio->port;
194 	struct portio_sysfs_entry *entry;
195 
196 	entry = container_of(attr, struct portio_sysfs_entry, attr);
197 
198 	if (!entry->show)
199 		return -EIO;
200 
201 	return entry->show(port, buf);
202 }
203 
204 static const struct sysfs_ops portio_sysfs_ops = {
205 	.show = portio_type_show,
206 };
207 
208 static struct kobj_type portio_attr_type = {
209 	.release	= portio_release,
210 	.sysfs_ops	= &portio_sysfs_ops,
211 	.default_attrs	= portio_attrs,
212 };
213 
214 static ssize_t name_show(struct device *dev,
215 			 struct device_attribute *attr, char *buf)
216 {
217 	struct uio_device *idev = dev_get_drvdata(dev);
218 	return sprintf(buf, "%s\n", idev->info->name);
219 }
220 static DEVICE_ATTR_RO(name);
221 
222 static ssize_t version_show(struct device *dev,
223 			    struct device_attribute *attr, char *buf)
224 {
225 	struct uio_device *idev = dev_get_drvdata(dev);
226 	return sprintf(buf, "%s\n", idev->info->version);
227 }
228 static DEVICE_ATTR_RO(version);
229 
230 static ssize_t event_show(struct device *dev,
231 			  struct device_attribute *attr, char *buf)
232 {
233 	struct uio_device *idev = dev_get_drvdata(dev);
234 	return sprintf(buf, "%u\n", (unsigned int)atomic_read(&idev->event));
235 }
236 static DEVICE_ATTR_RO(event);
237 
238 static struct attribute *uio_attrs[] = {
239 	&dev_attr_name.attr,
240 	&dev_attr_version.attr,
241 	&dev_attr_event.attr,
242 	NULL,
243 };
244 ATTRIBUTE_GROUPS(uio);
245 
246 /* UIO class infrastructure */
247 static struct class uio_class = {
248 	.name = "uio",
249 	.dev_groups = uio_groups,
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 	for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
267 		mem = &idev->info->mem[mi];
268 		if (mem->size == 0)
269 			break;
270 		if (!map_found) {
271 			map_found = 1;
272 			idev->map_dir = kobject_create_and_add("maps",
273 							&idev->dev->kobj);
274 			if (!idev->map_dir)
275 				goto err_map;
276 		}
277 		map = kzalloc(sizeof(*map), GFP_KERNEL);
278 		if (!map)
279 			goto err_map_kobj;
280 		kobject_init(&map->kobj, &map_attr_type);
281 		map->mem = mem;
282 		mem->map = map;
283 		ret = kobject_add(&map->kobj, idev->map_dir, "map%d", mi);
284 		if (ret)
285 			goto err_map_kobj;
286 		ret = kobject_uevent(&map->kobj, KOBJ_ADD);
287 		if (ret)
288 			goto err_map;
289 	}
290 
291 	for (pi = 0; pi < MAX_UIO_PORT_REGIONS; pi++) {
292 		port = &idev->info->port[pi];
293 		if (port->size == 0)
294 			break;
295 		if (!portio_found) {
296 			portio_found = 1;
297 			idev->portio_dir = kobject_create_and_add("portio",
298 							&idev->dev->kobj);
299 			if (!idev->portio_dir)
300 				goto err_portio;
301 		}
302 		portio = kzalloc(sizeof(*portio), GFP_KERNEL);
303 		if (!portio)
304 			goto err_portio_kobj;
305 		kobject_init(&portio->kobj, &portio_attr_type);
306 		portio->port = port;
307 		port->portio = portio;
308 		ret = kobject_add(&portio->kobj, idev->portio_dir,
309 							"port%d", pi);
310 		if (ret)
311 			goto err_portio_kobj;
312 		ret = kobject_uevent(&portio->kobj, KOBJ_ADD);
313 		if (ret)
314 			goto err_portio;
315 	}
316 
317 	return 0;
318 
319 err_portio:
320 	pi--;
321 err_portio_kobj:
322 	for (; pi >= 0; pi--) {
323 		port = &idev->info->port[pi];
324 		portio = port->portio;
325 		kobject_put(&portio->kobj);
326 	}
327 	kobject_put(idev->portio_dir);
328 err_map:
329 	mi--;
330 err_map_kobj:
331 	for (; 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 	dev_err(idev->dev, "error creating sysfs files (%d)\n", ret);
338 	return ret;
339 }
340 
341 static void uio_dev_del_attributes(struct uio_device *idev)
342 {
343 	int i;
344 	struct uio_mem *mem;
345 	struct uio_port *port;
346 
347 	for (i = 0; i < MAX_UIO_MAPS; i++) {
348 		mem = &idev->info->mem[i];
349 		if (mem->size == 0)
350 			break;
351 		kobject_put(&mem->map->kobj);
352 	}
353 	kobject_put(idev->map_dir);
354 
355 	for (i = 0; i < MAX_UIO_PORT_REGIONS; i++) {
356 		port = &idev->info->port[i];
357 		if (port->size == 0)
358 			break;
359 		kobject_put(&port->portio->kobj);
360 	}
361 	kobject_put(idev->portio_dir);
362 }
363 
364 static int uio_get_minor(struct uio_device *idev)
365 {
366 	int retval = -ENOMEM;
367 
368 	mutex_lock(&minor_lock);
369 	retval = idr_alloc(&uio_idr, idev, 0, UIO_MAX_DEVICES, GFP_KERNEL);
370 	if (retval >= 0) {
371 		idev->minor = retval;
372 		retval = 0;
373 	} else if (retval == -ENOSPC) {
374 		dev_err(idev->dev, "too many uio devices\n");
375 		retval = -EINVAL;
376 	}
377 	mutex_unlock(&minor_lock);
378 	return retval;
379 }
380 
381 static void uio_free_minor(struct uio_device *idev)
382 {
383 	mutex_lock(&minor_lock);
384 	idr_remove(&uio_idr, idev->minor);
385 	mutex_unlock(&minor_lock);
386 }
387 
388 /**
389  * uio_event_notify - trigger an interrupt event
390  * @info: UIO device capabilities
391  */
392 void uio_event_notify(struct uio_info *info)
393 {
394 	struct uio_device *idev = info->uio_dev;
395 
396 	atomic_inc(&idev->event);
397 	wake_up_interruptible(&idev->wait);
398 	kill_fasync(&idev->async_queue, SIGIO, POLL_IN);
399 }
400 EXPORT_SYMBOL_GPL(uio_event_notify);
401 
402 /**
403  * uio_interrupt - hardware interrupt handler
404  * @irq: IRQ number, can be UIO_IRQ_CYCLIC for cyclic timer
405  * @dev_id: Pointer to the devices uio_device structure
406  */
407 static irqreturn_t uio_interrupt(int irq, void *dev_id)
408 {
409 	struct uio_device *idev = (struct uio_device *)dev_id;
410 	irqreturn_t ret = idev->info->handler(irq, idev->info);
411 
412 	if (ret == IRQ_HANDLED)
413 		uio_event_notify(idev->info);
414 
415 	return ret;
416 }
417 
418 struct uio_listener {
419 	struct uio_device *dev;
420 	s32 event_count;
421 };
422 
423 static int uio_open(struct inode *inode, struct file *filep)
424 {
425 	struct uio_device *idev;
426 	struct uio_listener *listener;
427 	int ret = 0;
428 
429 	mutex_lock(&minor_lock);
430 	idev = idr_find(&uio_idr, iminor(inode));
431 	mutex_unlock(&minor_lock);
432 	if (!idev) {
433 		ret = -ENODEV;
434 		goto out;
435 	}
436 
437 	if (!try_module_get(idev->owner)) {
438 		ret = -ENODEV;
439 		goto out;
440 	}
441 
442 	listener = kmalloc(sizeof(*listener), GFP_KERNEL);
443 	if (!listener) {
444 		ret = -ENOMEM;
445 		goto err_alloc_listener;
446 	}
447 
448 	listener->dev = idev;
449 	listener->event_count = atomic_read(&idev->event);
450 	filep->private_data = listener;
451 
452 	if (idev->info->open) {
453 		ret = idev->info->open(idev->info, inode);
454 		if (ret)
455 			goto err_infoopen;
456 	}
457 	return 0;
458 
459 err_infoopen:
460 	kfree(listener);
461 
462 err_alloc_listener:
463 	module_put(idev->owner);
464 
465 out:
466 	return ret;
467 }
468 
469 static int uio_fasync(int fd, struct file *filep, int on)
470 {
471 	struct uio_listener *listener = filep->private_data;
472 	struct uio_device *idev = listener->dev;
473 
474 	return fasync_helper(fd, filep, on, &idev->async_queue);
475 }
476 
477 static int uio_release(struct inode *inode, struct file *filep)
478 {
479 	int ret = 0;
480 	struct uio_listener *listener = filep->private_data;
481 	struct uio_device *idev = listener->dev;
482 
483 	if (idev->info->release)
484 		ret = idev->info->release(idev->info, inode);
485 
486 	module_put(idev->owner);
487 	kfree(listener);
488 	return ret;
489 }
490 
491 static unsigned int uio_poll(struct file *filep, poll_table *wait)
492 {
493 	struct uio_listener *listener = filep->private_data;
494 	struct uio_device *idev = listener->dev;
495 
496 	if (!idev->info->irq)
497 		return -EIO;
498 
499 	poll_wait(filep, &idev->wait, wait);
500 	if (listener->event_count != atomic_read(&idev->event))
501 		return POLLIN | POLLRDNORM;
502 	return 0;
503 }
504 
505 static ssize_t uio_read(struct file *filep, char __user *buf,
506 			size_t count, loff_t *ppos)
507 {
508 	struct uio_listener *listener = filep->private_data;
509 	struct uio_device *idev = listener->dev;
510 	DECLARE_WAITQUEUE(wait, current);
511 	ssize_t retval;
512 	s32 event_count;
513 
514 	if (!idev->info->irq)
515 		return -EIO;
516 
517 	if (count != sizeof(s32))
518 		return -EINVAL;
519 
520 	add_wait_queue(&idev->wait, &wait);
521 
522 	do {
523 		set_current_state(TASK_INTERRUPTIBLE);
524 
525 		event_count = atomic_read(&idev->event);
526 		if (event_count != listener->event_count) {
527 			if (copy_to_user(buf, &event_count, count))
528 				retval = -EFAULT;
529 			else {
530 				listener->event_count = event_count;
531 				retval = count;
532 			}
533 			break;
534 		}
535 
536 		if (filep->f_flags & O_NONBLOCK) {
537 			retval = -EAGAIN;
538 			break;
539 		}
540 
541 		if (signal_pending(current)) {
542 			retval = -ERESTARTSYS;
543 			break;
544 		}
545 		schedule();
546 	} while (1);
547 
548 	__set_current_state(TASK_RUNNING);
549 	remove_wait_queue(&idev->wait, &wait);
550 
551 	return retval;
552 }
553 
554 static ssize_t uio_write(struct file *filep, const char __user *buf,
555 			size_t count, loff_t *ppos)
556 {
557 	struct uio_listener *listener = filep->private_data;
558 	struct uio_device *idev = listener->dev;
559 	ssize_t retval;
560 	s32 irq_on;
561 
562 	if (!idev->info->irq)
563 		return -EIO;
564 
565 	if (count != sizeof(s32))
566 		return -EINVAL;
567 
568 	if (!idev->info->irqcontrol)
569 		return -ENOSYS;
570 
571 	if (copy_from_user(&irq_on, buf, count))
572 		return -EFAULT;
573 
574 	retval = idev->info->irqcontrol(idev->info, irq_on);
575 
576 	return retval ? retval : sizeof(s32);
577 }
578 
579 static int uio_find_mem_index(struct vm_area_struct *vma)
580 {
581 	struct uio_device *idev = vma->vm_private_data;
582 
583 	if (vma->vm_pgoff < MAX_UIO_MAPS) {
584 		if (idev->info->mem[vma->vm_pgoff].size == 0)
585 			return -1;
586 		return (int)vma->vm_pgoff;
587 	}
588 	return -1;
589 }
590 
591 static int uio_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
592 {
593 	struct uio_device *idev = vma->vm_private_data;
594 	struct page *page;
595 	unsigned long offset;
596 	void *addr;
597 
598 	int mi = uio_find_mem_index(vma);
599 	if (mi < 0)
600 		return VM_FAULT_SIGBUS;
601 
602 	/*
603 	 * We need to subtract mi because userspace uses offset = N*PAGE_SIZE
604 	 * to use mem[N].
605 	 */
606 	offset = (vmf->pgoff - mi) << PAGE_SHIFT;
607 
608 	addr = (void *)(unsigned long)idev->info->mem[mi].addr + offset;
609 	if (idev->info->mem[mi].memtype == UIO_MEM_LOGICAL)
610 		page = virt_to_page(addr);
611 	else
612 		page = vmalloc_to_page(addr);
613 	get_page(page);
614 	vmf->page = page;
615 	return 0;
616 }
617 
618 static const struct vm_operations_struct uio_logical_vm_ops = {
619 	.fault = uio_vma_fault,
620 };
621 
622 static int uio_mmap_logical(struct vm_area_struct *vma)
623 {
624 	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
625 	vma->vm_ops = &uio_logical_vm_ops;
626 	return 0;
627 }
628 
629 static const struct vm_operations_struct uio_physical_vm_ops = {
630 #ifdef CONFIG_HAVE_IOREMAP_PROT
631 	.access = generic_access_phys,
632 #endif
633 };
634 
635 static int uio_mmap_physical(struct vm_area_struct *vma)
636 {
637 	struct uio_device *idev = vma->vm_private_data;
638 	int mi = uio_find_mem_index(vma);
639 	struct uio_mem *mem;
640 	if (mi < 0)
641 		return -EINVAL;
642 	mem = idev->info->mem + mi;
643 
644 	if (mem->addr & ~PAGE_MASK)
645 		return -ENODEV;
646 	if (vma->vm_end - vma->vm_start > mem->size)
647 		return -EINVAL;
648 
649 	vma->vm_ops = &uio_physical_vm_ops;
650 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
651 
652 	/*
653 	 * We cannot use the vm_iomap_memory() helper here,
654 	 * because vma->vm_pgoff is the map index we looked
655 	 * up above in uio_find_mem_index(), rather than an
656 	 * actual page offset into the mmap.
657 	 *
658 	 * So we just do the physical mmap without a page
659 	 * offset.
660 	 */
661 	return remap_pfn_range(vma,
662 			       vma->vm_start,
663 			       mem->addr >> PAGE_SHIFT,
664 			       vma->vm_end - vma->vm_start,
665 			       vma->vm_page_prot);
666 }
667 
668 static int uio_mmap(struct file *filep, struct vm_area_struct *vma)
669 {
670 	struct uio_listener *listener = filep->private_data;
671 	struct uio_device *idev = listener->dev;
672 	int mi;
673 	unsigned long requested_pages, actual_pages;
674 	int ret = 0;
675 
676 	if (vma->vm_end < vma->vm_start)
677 		return -EINVAL;
678 
679 	vma->vm_private_data = idev;
680 
681 	mi = uio_find_mem_index(vma);
682 	if (mi < 0)
683 		return -EINVAL;
684 
685 	requested_pages = vma_pages(vma);
686 	actual_pages = ((idev->info->mem[mi].addr & ~PAGE_MASK)
687 			+ idev->info->mem[mi].size + PAGE_SIZE -1) >> PAGE_SHIFT;
688 	if (requested_pages > actual_pages)
689 		return -EINVAL;
690 
691 	if (idev->info->mmap) {
692 		ret = idev->info->mmap(idev->info, vma);
693 		return ret;
694 	}
695 
696 	switch (idev->info->mem[mi].memtype) {
697 		case UIO_MEM_PHYS:
698 			return uio_mmap_physical(vma);
699 		case UIO_MEM_LOGICAL:
700 		case UIO_MEM_VIRTUAL:
701 			return uio_mmap_logical(vma);
702 		default:
703 			return -EINVAL;
704 	}
705 }
706 
707 static const struct file_operations uio_fops = {
708 	.owner		= THIS_MODULE,
709 	.open		= uio_open,
710 	.release	= uio_release,
711 	.read		= uio_read,
712 	.write		= uio_write,
713 	.mmap		= uio_mmap,
714 	.poll		= uio_poll,
715 	.fasync		= uio_fasync,
716 	.llseek		= noop_llseek,
717 };
718 
719 static int uio_major_init(void)
720 {
721 	static const char name[] = "uio";
722 	struct cdev *cdev = NULL;
723 	dev_t uio_dev = 0;
724 	int result;
725 
726 	result = alloc_chrdev_region(&uio_dev, 0, UIO_MAX_DEVICES, name);
727 	if (result)
728 		goto out;
729 
730 	result = -ENOMEM;
731 	cdev = cdev_alloc();
732 	if (!cdev)
733 		goto out_unregister;
734 
735 	cdev->owner = THIS_MODULE;
736 	cdev->ops = &uio_fops;
737 	kobject_set_name(&cdev->kobj, "%s", name);
738 
739 	result = cdev_add(cdev, uio_dev, UIO_MAX_DEVICES);
740 	if (result)
741 		goto out_put;
742 
743 	uio_major = MAJOR(uio_dev);
744 	uio_cdev = cdev;
745 	return 0;
746 out_put:
747 	kobject_put(&cdev->kobj);
748 out_unregister:
749 	unregister_chrdev_region(uio_dev, UIO_MAX_DEVICES);
750 out:
751 	return result;
752 }
753 
754 static void uio_major_cleanup(void)
755 {
756 	unregister_chrdev_region(MKDEV(uio_major, 0), UIO_MAX_DEVICES);
757 	cdev_del(uio_cdev);
758 }
759 
760 static int init_uio_class(void)
761 {
762 	int ret;
763 
764 	/* This is the first time in here, set everything up properly */
765 	ret = uio_major_init();
766 	if (ret)
767 		goto exit;
768 
769 	ret = class_register(&uio_class);
770 	if (ret) {
771 		printk(KERN_ERR "class_register failed for uio\n");
772 		goto err_class_register;
773 	}
774 	return 0;
775 
776 err_class_register:
777 	uio_major_cleanup();
778 exit:
779 	return ret;
780 }
781 
782 static void release_uio_class(void)
783 {
784 	class_unregister(&uio_class);
785 	uio_major_cleanup();
786 }
787 
788 /**
789  * uio_register_device - register a new userspace IO device
790  * @owner:	module that creates the new device
791  * @parent:	parent device
792  * @info:	UIO device capabilities
793  *
794  * returns zero on success or a negative error code.
795  */
796 int __uio_register_device(struct module *owner,
797 			  struct device *parent,
798 			  struct uio_info *info)
799 {
800 	struct uio_device *idev;
801 	int ret = 0;
802 
803 	if (!parent || !info || !info->name || !info->version)
804 		return -EINVAL;
805 
806 	info->uio_dev = NULL;
807 
808 	idev = devm_kzalloc(parent, sizeof(*idev), GFP_KERNEL);
809 	if (!idev) {
810 		return -ENOMEM;
811 	}
812 
813 	idev->owner = owner;
814 	idev->info = info;
815 	init_waitqueue_head(&idev->wait);
816 	atomic_set(&idev->event, 0);
817 
818 	ret = uio_get_minor(idev);
819 	if (ret)
820 		return ret;
821 
822 	idev->dev = device_create(&uio_class, parent,
823 				  MKDEV(uio_major, idev->minor), idev,
824 				  "uio%d", idev->minor);
825 	if (IS_ERR(idev->dev)) {
826 		printk(KERN_ERR "UIO: device register failed\n");
827 		ret = PTR_ERR(idev->dev);
828 		goto err_device_create;
829 	}
830 
831 	ret = uio_dev_add_attributes(idev);
832 	if (ret)
833 		goto err_uio_dev_add_attributes;
834 
835 	info->uio_dev = idev;
836 
837 	if (info->irq && (info->irq != UIO_IRQ_CUSTOM)) {
838 		ret = devm_request_irq(idev->dev, info->irq, uio_interrupt,
839 				  info->irq_flags, info->name, idev);
840 		if (ret)
841 			goto err_request_irq;
842 	}
843 
844 	return 0;
845 
846 err_request_irq:
847 	uio_dev_del_attributes(idev);
848 err_uio_dev_add_attributes:
849 	device_destroy(&uio_class, MKDEV(uio_major, idev->minor));
850 err_device_create:
851 	uio_free_minor(idev);
852 	return ret;
853 }
854 EXPORT_SYMBOL_GPL(__uio_register_device);
855 
856 /**
857  * uio_unregister_device - unregister a industrial IO device
858  * @info:	UIO device capabilities
859  *
860  */
861 void uio_unregister_device(struct uio_info *info)
862 {
863 	struct uio_device *idev;
864 
865 	if (!info || !info->uio_dev)
866 		return;
867 
868 	idev = info->uio_dev;
869 
870 	uio_free_minor(idev);
871 
872 	uio_dev_del_attributes(idev);
873 
874 	device_destroy(&uio_class, MKDEV(uio_major, idev->minor));
875 
876 	return;
877 }
878 EXPORT_SYMBOL_GPL(uio_unregister_device);
879 
880 static int __init uio_init(void)
881 {
882 	return init_uio_class();
883 }
884 
885 static void __exit uio_exit(void)
886 {
887 	release_uio_class();
888 }
889 
890 module_init(uio_init)
891 module_exit(uio_exit)
892 MODULE_LICENSE("GPL v2");
893