xref: /linux/drivers/uio/uio.c (revision 092e0e7e520a1fca03e13c9f2d157432a8657ff2) 
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/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/uio_driver.h>
27 
28 #define UIO_MAX_DEVICES 255
29 
30 struct uio_device {
31 	struct module		*owner;
32 	struct device		*dev;
33 	int			minor;
34 	atomic_t		event;
35 	struct fasync_struct	*async_queue;
36 	wait_queue_head_t	wait;
37 	int			vma_count;
38 	struct uio_info		*info;
39 	struct kobject		*map_dir;
40 	struct kobject		*portio_dir;
41 };
42 
43 static int uio_major;
44 static DEFINE_IDR(uio_idr);
45 static const struct file_operations uio_fops;
46 
47 /* UIO class infrastructure */
48 static struct uio_class {
49 	struct kref kref;
50 	struct class *class;
51 } *uio_class;
52 
53 /* Protect idr accesses */
54 static DEFINE_MUTEX(minor_lock);
55 
56 /*
57  * attributes
58  */
59 
60 struct uio_map {
61 	struct kobject kobj;
62 	struct uio_mem *mem;
63 };
64 #define to_map(map) container_of(map, struct uio_map, kobj)
65 
66 static ssize_t map_name_show(struct uio_mem *mem, char *buf)
67 {
68 	if (unlikely(!mem->name))
69 		mem->name = "";
70 
71 	return sprintf(buf, "%s\n", mem->name);
72 }
73 
74 static ssize_t map_addr_show(struct uio_mem *mem, char *buf)
75 {
76 	return sprintf(buf, "0x%lx\n", mem->addr);
77 }
78 
79 static ssize_t map_size_show(struct uio_mem *mem, char *buf)
80 {
81 	return sprintf(buf, "0x%lx\n", mem->size);
82 }
83 
84 static ssize_t map_offset_show(struct uio_mem *mem, char *buf)
85 {
86 	return sprintf(buf, "0x%lx\n", mem->addr & ~PAGE_MASK);
87 }
88 
89 struct map_sysfs_entry {
90 	struct attribute attr;
91 	ssize_t (*show)(struct uio_mem *, char *);
92 	ssize_t (*store)(struct uio_mem *, const char *, size_t);
93 };
94 
95 static struct map_sysfs_entry name_attribute =
96 	__ATTR(name, S_IRUGO, map_name_show, NULL);
97 static struct map_sysfs_entry addr_attribute =
98 	__ATTR(addr, S_IRUGO, map_addr_show, NULL);
99 static struct map_sysfs_entry size_attribute =
100 	__ATTR(size, S_IRUGO, map_size_show, NULL);
101 static struct map_sysfs_entry offset_attribute =
102 	__ATTR(offset, S_IRUGO, map_offset_show, NULL);
103 
104 static struct attribute *attrs[] = {
105 	&name_attribute.attr,
106 	&addr_attribute.attr,
107 	&size_attribute.attr,
108 	&offset_attribute.attr,
109 	NULL,	/* need to NULL terminate the list of attributes */
110 };
111 
112 static void map_release(struct kobject *kobj)
113 {
114 	struct uio_map *map = to_map(kobj);
115 	kfree(map);
116 }
117 
118 static ssize_t map_type_show(struct kobject *kobj, struct attribute *attr,
119 			     char *buf)
120 {
121 	struct uio_map *map = to_map(kobj);
122 	struct uio_mem *mem = map->mem;
123 	struct map_sysfs_entry *entry;
124 
125 	entry = container_of(attr, struct map_sysfs_entry, attr);
126 
127 	if (!entry->show)
128 		return -EIO;
129 
130 	return entry->show(mem, buf);
131 }
132 
133 static const struct sysfs_ops map_sysfs_ops = {
134 	.show = map_type_show,
135 };
136 
137 static struct kobj_type map_attr_type = {
138 	.release	= map_release,
139 	.sysfs_ops	= &map_sysfs_ops,
140 	.default_attrs	= attrs,
141 };
142 
143 struct uio_portio {
144 	struct kobject kobj;
145 	struct uio_port *port;
146 };
147 #define to_portio(portio) container_of(portio, struct uio_portio, kobj)
148 
149 static ssize_t portio_name_show(struct uio_port *port, char *buf)
150 {
151 	if (unlikely(!port->name))
152 		port->name = "";
153 
154 	return sprintf(buf, "%s\n", port->name);
155 }
156 
157 static ssize_t portio_start_show(struct uio_port *port, char *buf)
158 {
159 	return sprintf(buf, "0x%lx\n", port->start);
160 }
161 
162 static ssize_t portio_size_show(struct uio_port *port, char *buf)
163 {
164 	return sprintf(buf, "0x%lx\n", port->size);
165 }
166 
167 static ssize_t portio_porttype_show(struct uio_port *port, char *buf)
168 {
169 	const char *porttypes[] = {"none", "x86", "gpio", "other"};
170 
171 	if ((port->porttype < 0) || (port->porttype > UIO_PORT_OTHER))
172 		return -EINVAL;
173 
174 	return sprintf(buf, "port_%s\n", porttypes[port->porttype]);
175 }
176 
177 struct portio_sysfs_entry {
178 	struct attribute attr;
179 	ssize_t (*show)(struct uio_port *, char *);
180 	ssize_t (*store)(struct uio_port *, const char *, size_t);
181 };
182 
183 static struct portio_sysfs_entry portio_name_attribute =
184 	__ATTR(name, S_IRUGO, portio_name_show, NULL);
185 static struct portio_sysfs_entry portio_start_attribute =
186 	__ATTR(start, S_IRUGO, portio_start_show, NULL);
187 static struct portio_sysfs_entry portio_size_attribute =
188 	__ATTR(size, S_IRUGO, portio_size_show, NULL);
189 static struct portio_sysfs_entry portio_porttype_attribute =
190 	__ATTR(porttype, S_IRUGO, portio_porttype_show, NULL);
191 
192 static struct attribute *portio_attrs[] = {
193 	&portio_name_attribute.attr,
194 	&portio_start_attribute.attr,
195 	&portio_size_attribute.attr,
196 	&portio_porttype_attribute.attr,
197 	NULL,
198 };
199 
200 static void portio_release(struct kobject *kobj)
201 {
202 	struct uio_portio *portio = to_portio(kobj);
203 	kfree(portio);
204 }
205 
206 static ssize_t portio_type_show(struct kobject *kobj, struct attribute *attr,
207 			     char *buf)
208 {
209 	struct uio_portio *portio = to_portio(kobj);
210 	struct uio_port *port = portio->port;
211 	struct portio_sysfs_entry *entry;
212 
213 	entry = container_of(attr, struct portio_sysfs_entry, attr);
214 
215 	if (!entry->show)
216 		return -EIO;
217 
218 	return entry->show(port, buf);
219 }
220 
221 static const struct sysfs_ops portio_sysfs_ops = {
222 	.show = portio_type_show,
223 };
224 
225 static struct kobj_type portio_attr_type = {
226 	.release	= portio_release,
227 	.sysfs_ops	= &portio_sysfs_ops,
228 	.default_attrs	= portio_attrs,
229 };
230 
231 static ssize_t show_name(struct device *dev,
232 			 struct device_attribute *attr, char *buf)
233 {
234 	struct uio_device *idev = dev_get_drvdata(dev);
235 	if (idev)
236 		return sprintf(buf, "%s\n", idev->info->name);
237 	else
238 		return -ENODEV;
239 }
240 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
241 
242 static ssize_t show_version(struct device *dev,
243 			    struct device_attribute *attr, char *buf)
244 {
245 	struct uio_device *idev = dev_get_drvdata(dev);
246 	if (idev)
247 		return sprintf(buf, "%s\n", idev->info->version);
248 	else
249 		return -ENODEV;
250 }
251 static DEVICE_ATTR(version, S_IRUGO, show_version, NULL);
252 
253 static ssize_t show_event(struct device *dev,
254 			  struct device_attribute *attr, char *buf)
255 {
256 	struct uio_device *idev = dev_get_drvdata(dev);
257 	if (idev)
258 		return sprintf(buf, "%u\n",
259 				(unsigned int)atomic_read(&idev->event));
260 	else
261 		return -ENODEV;
262 }
263 static DEVICE_ATTR(event, S_IRUGO, show_event, NULL);
264 
265 static struct attribute *uio_attrs[] = {
266 	&dev_attr_name.attr,
267 	&dev_attr_version.attr,
268 	&dev_attr_event.attr,
269 	NULL,
270 };
271 
272 static struct attribute_group uio_attr_grp = {
273 	.attrs = uio_attrs,
274 };
275 
276 /*
277  * device functions
278  */
279 static int uio_dev_add_attributes(struct uio_device *idev)
280 {
281 	int ret;
282 	int mi, pi;
283 	int map_found = 0;
284 	int portio_found = 0;
285 	struct uio_mem *mem;
286 	struct uio_map *map;
287 	struct uio_port *port;
288 	struct uio_portio *portio;
289 
290 	ret = sysfs_create_group(&idev->dev->kobj, &uio_attr_grp);
291 	if (ret)
292 		goto err_group;
293 
294 	for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
295 		mem = &idev->info->mem[mi];
296 		if (mem->size == 0)
297 			break;
298 		if (!map_found) {
299 			map_found = 1;
300 			idev->map_dir = kobject_create_and_add("maps",
301 							&idev->dev->kobj);
302 			if (!idev->map_dir)
303 				goto err_map;
304 		}
305 		map = kzalloc(sizeof(*map), GFP_KERNEL);
306 		if (!map)
307 			goto err_map;
308 		kobject_init(&map->kobj, &map_attr_type);
309 		map->mem = mem;
310 		mem->map = map;
311 		ret = kobject_add(&map->kobj, idev->map_dir, "map%d", mi);
312 		if (ret)
313 			goto err_map;
314 		ret = kobject_uevent(&map->kobj, KOBJ_ADD);
315 		if (ret)
316 			goto err_map;
317 	}
318 
319 	for (pi = 0; pi < MAX_UIO_PORT_REGIONS; pi++) {
320 		port = &idev->info->port[pi];
321 		if (port->size == 0)
322 			break;
323 		if (!portio_found) {
324 			portio_found = 1;
325 			idev->portio_dir = kobject_create_and_add("portio",
326 							&idev->dev->kobj);
327 			if (!idev->portio_dir)
328 				goto err_portio;
329 		}
330 		portio = kzalloc(sizeof(*portio), GFP_KERNEL);
331 		if (!portio)
332 			goto err_portio;
333 		kobject_init(&portio->kobj, &portio_attr_type);
334 		portio->port = port;
335 		port->portio = portio;
336 		ret = kobject_add(&portio->kobj, idev->portio_dir,
337 							"port%d", pi);
338 		if (ret)
339 			goto err_portio;
340 		ret = kobject_uevent(&portio->kobj, KOBJ_ADD);
341 		if (ret)
342 			goto err_portio;
343 	}
344 
345 	return 0;
346 
347 err_portio:
348 	for (pi--; pi >= 0; pi--) {
349 		port = &idev->info->port[pi];
350 		portio = port->portio;
351 		kobject_put(&portio->kobj);
352 	}
353 	kobject_put(idev->portio_dir);
354 err_map:
355 	for (mi--; mi>=0; mi--) {
356 		mem = &idev->info->mem[mi];
357 		map = mem->map;
358 		kobject_put(&map->kobj);
359 	}
360 	kobject_put(idev->map_dir);
361 	sysfs_remove_group(&idev->dev->kobj, &uio_attr_grp);
362 err_group:
363 	dev_err(idev->dev, "error creating sysfs files (%d)\n", ret);
364 	return ret;
365 }
366 
367 static void uio_dev_del_attributes(struct uio_device *idev)
368 {
369 	int i;
370 	struct uio_mem *mem;
371 	struct uio_port *port;
372 
373 	for (i = 0; i < MAX_UIO_MAPS; i++) {
374 		mem = &idev->info->mem[i];
375 		if (mem->size == 0)
376 			break;
377 		kobject_put(&mem->map->kobj);
378 	}
379 	kobject_put(idev->map_dir);
380 
381 	for (i = 0; i < MAX_UIO_PORT_REGIONS; i++) {
382 		port = &idev->info->port[i];
383 		if (port->size == 0)
384 			break;
385 		kobject_put(&port->portio->kobj);
386 	}
387 	kobject_put(idev->portio_dir);
388 
389 	sysfs_remove_group(&idev->dev->kobj, &uio_attr_grp);
390 }
391 
392 static int uio_get_minor(struct uio_device *idev)
393 {
394 	int retval = -ENOMEM;
395 	int id;
396 
397 	mutex_lock(&minor_lock);
398 	if (idr_pre_get(&uio_idr, GFP_KERNEL) == 0)
399 		goto exit;
400 
401 	retval = idr_get_new(&uio_idr, idev, &id);
402 	if (retval < 0) {
403 		if (retval == -EAGAIN)
404 			retval = -ENOMEM;
405 		goto exit;
406 	}
407 	idev->minor = id & MAX_ID_MASK;
408 exit:
409 	mutex_unlock(&minor_lock);
410 	return retval;
411 }
412 
413 static void uio_free_minor(struct uio_device *idev)
414 {
415 	mutex_lock(&minor_lock);
416 	idr_remove(&uio_idr, idev->minor);
417 	mutex_unlock(&minor_lock);
418 }
419 
420 /**
421  * uio_event_notify - trigger an interrupt event
422  * @info: UIO device capabilities
423  */
424 void uio_event_notify(struct uio_info *info)
425 {
426 	struct uio_device *idev = info->uio_dev;
427 
428 	atomic_inc(&idev->event);
429 	wake_up_interruptible(&idev->wait);
430 	kill_fasync(&idev->async_queue, SIGIO, POLL_IN);
431 }
432 EXPORT_SYMBOL_GPL(uio_event_notify);
433 
434 /**
435  * uio_interrupt - hardware interrupt handler
436  * @irq: IRQ number, can be UIO_IRQ_CYCLIC for cyclic timer
437  * @dev_id: Pointer to the devices uio_device structure
438  */
439 static irqreturn_t uio_interrupt(int irq, void *dev_id)
440 {
441 	struct uio_device *idev = (struct uio_device *)dev_id;
442 	irqreturn_t ret = idev->info->handler(irq, idev->info);
443 
444 	if (ret == IRQ_HANDLED)
445 		uio_event_notify(idev->info);
446 
447 	return ret;
448 }
449 
450 struct uio_listener {
451 	struct uio_device *dev;
452 	s32 event_count;
453 };
454 
455 static int uio_open(struct inode *inode, struct file *filep)
456 {
457 	struct uio_device *idev;
458 	struct uio_listener *listener;
459 	int ret = 0;
460 
461 	mutex_lock(&minor_lock);
462 	idev = idr_find(&uio_idr, iminor(inode));
463 	mutex_unlock(&minor_lock);
464 	if (!idev) {
465 		ret = -ENODEV;
466 		goto out;
467 	}
468 
469 	if (!try_module_get(idev->owner)) {
470 		ret = -ENODEV;
471 		goto out;
472 	}
473 
474 	listener = kmalloc(sizeof(*listener), GFP_KERNEL);
475 	if (!listener) {
476 		ret = -ENOMEM;
477 		goto err_alloc_listener;
478 	}
479 
480 	listener->dev = idev;
481 	listener->event_count = atomic_read(&idev->event);
482 	filep->private_data = listener;
483 
484 	if (idev->info->open) {
485 		ret = idev->info->open(idev->info, inode);
486 		if (ret)
487 			goto err_infoopen;
488 	}
489 	return 0;
490 
491 err_infoopen:
492 	kfree(listener);
493 
494 err_alloc_listener:
495 	module_put(idev->owner);
496 
497 out:
498 	return ret;
499 }
500 
501 static int uio_fasync(int fd, struct file *filep, int on)
502 {
503 	struct uio_listener *listener = filep->private_data;
504 	struct uio_device *idev = listener->dev;
505 
506 	return fasync_helper(fd, filep, on, &idev->async_queue);
507 }
508 
509 static int uio_release(struct inode *inode, struct file *filep)
510 {
511 	int ret = 0;
512 	struct uio_listener *listener = filep->private_data;
513 	struct uio_device *idev = listener->dev;
514 
515 	if (idev->info->release)
516 		ret = idev->info->release(idev->info, inode);
517 
518 	module_put(idev->owner);
519 	kfree(listener);
520 	return ret;
521 }
522 
523 static unsigned int uio_poll(struct file *filep, poll_table *wait)
524 {
525 	struct uio_listener *listener = filep->private_data;
526 	struct uio_device *idev = listener->dev;
527 
528 	if (idev->info->irq == UIO_IRQ_NONE)
529 		return -EIO;
530 
531 	poll_wait(filep, &idev->wait, wait);
532 	if (listener->event_count != atomic_read(&idev->event))
533 		return POLLIN | POLLRDNORM;
534 	return 0;
535 }
536 
537 static ssize_t uio_read(struct file *filep, char __user *buf,
538 			size_t count, loff_t *ppos)
539 {
540 	struct uio_listener *listener = filep->private_data;
541 	struct uio_device *idev = listener->dev;
542 	DECLARE_WAITQUEUE(wait, current);
543 	ssize_t retval;
544 	s32 event_count;
545 
546 	if (idev->info->irq == UIO_IRQ_NONE)
547 		return -EIO;
548 
549 	if (count != sizeof(s32))
550 		return -EINVAL;
551 
552 	add_wait_queue(&idev->wait, &wait);
553 
554 	do {
555 		set_current_state(TASK_INTERRUPTIBLE);
556 
557 		event_count = atomic_read(&idev->event);
558 		if (event_count != listener->event_count) {
559 			if (copy_to_user(buf, &event_count, count))
560 				retval = -EFAULT;
561 			else {
562 				listener->event_count = event_count;
563 				retval = count;
564 			}
565 			break;
566 		}
567 
568 		if (filep->f_flags & O_NONBLOCK) {
569 			retval = -EAGAIN;
570 			break;
571 		}
572 
573 		if (signal_pending(current)) {
574 			retval = -ERESTARTSYS;
575 			break;
576 		}
577 		schedule();
578 	} while (1);
579 
580 	__set_current_state(TASK_RUNNING);
581 	remove_wait_queue(&idev->wait, &wait);
582 
583 	return retval;
584 }
585 
586 static ssize_t uio_write(struct file *filep, const char __user *buf,
587 			size_t count, loff_t *ppos)
588 {
589 	struct uio_listener *listener = filep->private_data;
590 	struct uio_device *idev = listener->dev;
591 	ssize_t retval;
592 	s32 irq_on;
593 
594 	if (idev->info->irq == UIO_IRQ_NONE)
595 		return -EIO;
596 
597 	if (count != sizeof(s32))
598 		return -EINVAL;
599 
600 	if (!idev->info->irqcontrol)
601 		return -ENOSYS;
602 
603 	if (copy_from_user(&irq_on, buf, count))
604 		return -EFAULT;
605 
606 	retval = idev->info->irqcontrol(idev->info, irq_on);
607 
608 	return retval ? retval : sizeof(s32);
609 }
610 
611 static int uio_find_mem_index(struct vm_area_struct *vma)
612 {
613 	int mi;
614 	struct uio_device *idev = vma->vm_private_data;
615 
616 	for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
617 		if (idev->info->mem[mi].size == 0)
618 			return -1;
619 		if (vma->vm_pgoff == mi)
620 			return mi;
621 	}
622 	return -1;
623 }
624 
625 static void uio_vma_open(struct vm_area_struct *vma)
626 {
627 	struct uio_device *idev = vma->vm_private_data;
628 	idev->vma_count++;
629 }
630 
631 static void uio_vma_close(struct vm_area_struct *vma)
632 {
633 	struct uio_device *idev = vma->vm_private_data;
634 	idev->vma_count--;
635 }
636 
637 static int uio_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
638 {
639 	struct uio_device *idev = vma->vm_private_data;
640 	struct page *page;
641 	unsigned long offset;
642 
643 	int mi = uio_find_mem_index(vma);
644 	if (mi < 0)
645 		return VM_FAULT_SIGBUS;
646 
647 	/*
648 	 * We need to subtract mi because userspace uses offset = N*PAGE_SIZE
649 	 * to use mem[N].
650 	 */
651 	offset = (vmf->pgoff - mi) << PAGE_SHIFT;
652 
653 	if (idev->info->mem[mi].memtype == UIO_MEM_LOGICAL)
654 		page = virt_to_page(idev->info->mem[mi].addr + offset);
655 	else
656 		page = vmalloc_to_page((void *)idev->info->mem[mi].addr
657 							+ offset);
658 	get_page(page);
659 	vmf->page = page;
660 	return 0;
661 }
662 
663 static const struct vm_operations_struct uio_vm_ops = {
664 	.open = uio_vma_open,
665 	.close = uio_vma_close,
666 	.fault = uio_vma_fault,
667 };
668 
669 static int uio_mmap_physical(struct vm_area_struct *vma)
670 {
671 	struct uio_device *idev = vma->vm_private_data;
672 	int mi = uio_find_mem_index(vma);
673 	if (mi < 0)
674 		return -EINVAL;
675 
676 	vma->vm_flags |= VM_IO | VM_RESERVED;
677 
678 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
679 
680 	return remap_pfn_range(vma,
681 			       vma->vm_start,
682 			       idev->info->mem[mi].addr >> PAGE_SHIFT,
683 			       vma->vm_end - vma->vm_start,
684 			       vma->vm_page_prot);
685 }
686 
687 static int uio_mmap_logical(struct vm_area_struct *vma)
688 {
689 	vma->vm_flags |= VM_RESERVED;
690 	vma->vm_ops = &uio_vm_ops;
691 	uio_vma_open(vma);
692 	return 0;
693 }
694 
695 static int uio_mmap(struct file *filep, struct vm_area_struct *vma)
696 {
697 	struct uio_listener *listener = filep->private_data;
698 	struct uio_device *idev = listener->dev;
699 	int mi;
700 	unsigned long requested_pages, actual_pages;
701 	int ret = 0;
702 
703 	if (vma->vm_end < vma->vm_start)
704 		return -EINVAL;
705 
706 	vma->vm_private_data = idev;
707 
708 	mi = uio_find_mem_index(vma);
709 	if (mi < 0)
710 		return -EINVAL;
711 
712 	requested_pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
713 	actual_pages = ((idev->info->mem[mi].addr & ~PAGE_MASK)
714 			+ idev->info->mem[mi].size + PAGE_SIZE -1) >> PAGE_SHIFT;
715 	if (requested_pages > actual_pages)
716 		return -EINVAL;
717 
718 	if (idev->info->mmap) {
719 		ret = idev->info->mmap(idev->info, vma);
720 		return ret;
721 	}
722 
723 	switch (idev->info->mem[mi].memtype) {
724 		case UIO_MEM_PHYS:
725 			return uio_mmap_physical(vma);
726 		case UIO_MEM_LOGICAL:
727 		case UIO_MEM_VIRTUAL:
728 			return uio_mmap_logical(vma);
729 		default:
730 			return -EINVAL;
731 	}
732 }
733 
734 static const struct file_operations uio_fops = {
735 	.owner		= THIS_MODULE,
736 	.open		= uio_open,
737 	.release	= uio_release,
738 	.read		= uio_read,
739 	.write		= uio_write,
740 	.mmap		= uio_mmap,
741 	.poll		= uio_poll,
742 	.fasync		= uio_fasync,
743 	.llseek		= noop_llseek,
744 };
745 
746 static int uio_major_init(void)
747 {
748 	uio_major = register_chrdev(0, "uio", &uio_fops);
749 	if (uio_major < 0)
750 		return uio_major;
751 	return 0;
752 }
753 
754 static void uio_major_cleanup(void)
755 {
756 	unregister_chrdev(uio_major, "uio");
757 }
758 
759 static int init_uio_class(void)
760 {
761 	int ret = 0;
762 
763 	if (uio_class != NULL) {
764 		kref_get(&uio_class->kref);
765 		goto exit;
766 	}
767 
768 	/* This is the first time in here, set everything up properly */
769 	ret = uio_major_init();
770 	if (ret)
771 		goto exit;
772 
773 	uio_class = kzalloc(sizeof(*uio_class), GFP_KERNEL);
774 	if (!uio_class) {
775 		ret = -ENOMEM;
776 		goto err_kzalloc;
777 	}
778 
779 	kref_init(&uio_class->kref);
780 	uio_class->class = class_create(THIS_MODULE, "uio");
781 	if (IS_ERR(uio_class->class)) {
782 		ret = IS_ERR(uio_class->class);
783 		printk(KERN_ERR "class_create failed for uio\n");
784 		goto err_class_create;
785 	}
786 	return 0;
787 
788 err_class_create:
789 	kfree(uio_class);
790 	uio_class = NULL;
791 err_kzalloc:
792 	uio_major_cleanup();
793 exit:
794 	return ret;
795 }
796 
797 static void release_uio_class(struct kref *kref)
798 {
799 	/* Ok, we cheat as we know we only have one uio_class */
800 	class_destroy(uio_class->class);
801 	kfree(uio_class);
802 	uio_major_cleanup();
803 	uio_class = NULL;
804 }
805 
806 static void uio_class_destroy(void)
807 {
808 	if (uio_class)
809 		kref_put(&uio_class->kref, release_uio_class);
810 }
811 
812 /**
813  * uio_register_device - register a new userspace IO device
814  * @owner:	module that creates the new device
815  * @parent:	parent device
816  * @info:	UIO device capabilities
817  *
818  * returns zero on success or a negative error code.
819  */
820 int __uio_register_device(struct module *owner,
821 			  struct device *parent,
822 			  struct uio_info *info)
823 {
824 	struct uio_device *idev;
825 	int ret = 0;
826 
827 	if (!parent || !info || !info->name || !info->version)
828 		return -EINVAL;
829 
830 	info->uio_dev = NULL;
831 
832 	ret = init_uio_class();
833 	if (ret)
834 		return ret;
835 
836 	idev = kzalloc(sizeof(*idev), GFP_KERNEL);
837 	if (!idev) {
838 		ret = -ENOMEM;
839 		goto err_kzalloc;
840 	}
841 
842 	idev->owner = owner;
843 	idev->info = info;
844 	init_waitqueue_head(&idev->wait);
845 	atomic_set(&idev->event, 0);
846 
847 	ret = uio_get_minor(idev);
848 	if (ret)
849 		goto err_get_minor;
850 
851 	idev->dev = device_create(uio_class->class, parent,
852 				  MKDEV(uio_major, idev->minor), idev,
853 				  "uio%d", idev->minor);
854 	if (IS_ERR(idev->dev)) {
855 		printk(KERN_ERR "UIO: device register failed\n");
856 		ret = PTR_ERR(idev->dev);
857 		goto err_device_create;
858 	}
859 
860 	ret = uio_dev_add_attributes(idev);
861 	if (ret)
862 		goto err_uio_dev_add_attributes;
863 
864 	info->uio_dev = idev;
865 
866 	if (idev->info->irq >= 0) {
867 		ret = request_irq(idev->info->irq, uio_interrupt,
868 				  idev->info->irq_flags, idev->info->name, idev);
869 		if (ret)
870 			goto err_request_irq;
871 	}
872 
873 	return 0;
874 
875 err_request_irq:
876 	uio_dev_del_attributes(idev);
877 err_uio_dev_add_attributes:
878 	device_destroy(uio_class->class, MKDEV(uio_major, idev->minor));
879 err_device_create:
880 	uio_free_minor(idev);
881 err_get_minor:
882 	kfree(idev);
883 err_kzalloc:
884 	uio_class_destroy();
885 	return ret;
886 }
887 EXPORT_SYMBOL_GPL(__uio_register_device);
888 
889 /**
890  * uio_unregister_device - unregister a industrial IO device
891  * @info:	UIO device capabilities
892  *
893  */
894 void uio_unregister_device(struct uio_info *info)
895 {
896 	struct uio_device *idev;
897 
898 	if (!info || !info->uio_dev)
899 		return;
900 
901 	idev = info->uio_dev;
902 
903 	uio_free_minor(idev);
904 
905 	if (info->irq >= 0)
906 		free_irq(info->irq, idev);
907 
908 	uio_dev_del_attributes(idev);
909 
910 	dev_set_drvdata(idev->dev, NULL);
911 	device_destroy(uio_class->class, MKDEV(uio_major, idev->minor));
912 	kfree(idev);
913 	uio_class_destroy();
914 
915 	return;
916 }
917 EXPORT_SYMBOL_GPL(uio_unregister_device);
918 
919 static int __init uio_init(void)
920 {
921 	return 0;
922 }
923 
924 static void __exit uio_exit(void)
925 {
926 }
927 
928 module_init(uio_init)
929 module_exit(uio_exit)
930 MODULE_LICENSE("GPL v2");
931