xref: /openbmc/linux/drivers/uio/uio.c (revision c21b37f6)
1 /*
2  * drivers/uio/uio.c
3  *
4  * Copyright(C) 2005, Benedikt Spranger <b.spranger@linutronix.de>
5  * Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
6  * Copyright(C) 2006, Hans J. Koch <hjk@linutronix.de>
7  * Copyright(C) 2006, Greg Kroah-Hartman <greg@kroah.com>
8  *
9  * Userspace IO
10  *
11  * Base Functions
12  *
13  * Licensed under the GPLv2 only.
14  */
15 
16 #include <linux/module.h>
17 #include <linux/init.h>
18 #include <linux/poll.h>
19 #include <linux/device.h>
20 #include <linux/mm.h>
21 #include <linux/idr.h>
22 #include <linux/string.h>
23 #include <linux/kobject.h>
24 #include <linux/uio_driver.h>
25 
26 #define UIO_MAX_DEVICES 255
27 
28 struct uio_device {
29 	struct module		*owner;
30 	struct device		*dev;
31 	int			minor;
32 	atomic_t		event;
33 	struct fasync_struct	*async_queue;
34 	wait_queue_head_t	wait;
35 	int			vma_count;
36 	struct uio_info		*info;
37 	struct kset 		map_attr_kset;
38 };
39 
40 static int uio_major;
41 static DEFINE_IDR(uio_idr);
42 static struct file_operations uio_fops;
43 
44 /* UIO class infrastructure */
45 static struct uio_class {
46 	struct kref kref;
47 	struct class *class;
48 } *uio_class;
49 
50 /*
51  * attributes
52  */
53 
54 static struct attribute attr_addr = {
55 	.name  = "addr",
56 	.mode  = S_IRUGO,
57 };
58 
59 static struct attribute attr_size = {
60 	.name  = "size",
61 	.mode  = S_IRUGO,
62 };
63 
64 static struct attribute* map_attrs[] = {
65 	&attr_addr, &attr_size, NULL
66 };
67 
68 static ssize_t map_attr_show(struct kobject *kobj, struct attribute *attr,
69 			     char *buf)
70 {
71 	struct uio_mem *mem = container_of(kobj, struct uio_mem, kobj);
72 
73 	if (strncmp(attr->name,"addr",4) == 0)
74 		return sprintf(buf, "0x%lx\n", mem->addr);
75 
76 	if (strncmp(attr->name,"size",4) == 0)
77 		return sprintf(buf, "0x%lx\n", mem->size);
78 
79 	return -ENODEV;
80 }
81 
82 static void map_attr_release(struct kobject *kobj)
83 {
84 	/* TODO ??? */
85 }
86 
87 static struct sysfs_ops map_attr_ops = {
88 	.show  = map_attr_show,
89 };
90 
91 static struct kobj_type map_attr_type = {
92 	.release	= map_attr_release,
93 	.sysfs_ops	= &map_attr_ops,
94 	.default_attrs	= map_attrs,
95 };
96 
97 static ssize_t show_name(struct device *dev,
98 			 struct device_attribute *attr, char *buf)
99 {
100 	struct uio_device *idev = dev_get_drvdata(dev);
101 	if (idev)
102 		return sprintf(buf, "%s\n", idev->info->name);
103 	else
104 		return -ENODEV;
105 }
106 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
107 
108 static ssize_t show_version(struct device *dev,
109 			    struct device_attribute *attr, char *buf)
110 {
111 	struct uio_device *idev = dev_get_drvdata(dev);
112 	if (idev)
113 		return sprintf(buf, "%s\n", idev->info->version);
114 	else
115 		return -ENODEV;
116 }
117 static DEVICE_ATTR(version, S_IRUGO, show_version, NULL);
118 
119 static ssize_t show_event(struct device *dev,
120 			  struct device_attribute *attr, char *buf)
121 {
122 	struct uio_device *idev = dev_get_drvdata(dev);
123 	if (idev)
124 		return sprintf(buf, "%u\n",
125 				(unsigned int)atomic_read(&idev->event));
126 	else
127 		return -ENODEV;
128 }
129 static DEVICE_ATTR(event, S_IRUGO, show_event, NULL);
130 
131 static struct attribute *uio_attrs[] = {
132 	&dev_attr_name.attr,
133 	&dev_attr_version.attr,
134 	&dev_attr_event.attr,
135 	NULL,
136 };
137 
138 static struct attribute_group uio_attr_grp = {
139 	.attrs = uio_attrs,
140 };
141 
142 /*
143  * device functions
144  */
145 static int uio_dev_add_attributes(struct uio_device *idev)
146 {
147 	int ret;
148 	int mi;
149 	int map_found = 0;
150 	struct uio_mem *mem;
151 
152 	ret = sysfs_create_group(&idev->dev->kobj, &uio_attr_grp);
153 	if (ret)
154 		goto err_group;
155 
156 	for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
157 		mem = &idev->info->mem[mi];
158 		if (mem->size == 0)
159 			break;
160 		if (!map_found) {
161 			map_found = 1;
162 			kobject_set_name(&idev->map_attr_kset.kobj,"maps");
163 			idev->map_attr_kset.ktype = &map_attr_type;
164 			idev->map_attr_kset.kobj.parent = &idev->dev->kobj;
165 			ret = kset_register(&idev->map_attr_kset);
166 			if (ret)
167 				goto err_remove_group;
168 		}
169 		kobject_init(&mem->kobj);
170 		kobject_set_name(&mem->kobj,"map%d",mi);
171 		mem->kobj.parent = &idev->map_attr_kset.kobj;
172 		mem->kobj.kset = &idev->map_attr_kset;
173 		ret = kobject_add(&mem->kobj);
174 		if (ret)
175 			goto err_remove_maps;
176 	}
177 
178 	return 0;
179 
180 err_remove_maps:
181 	for (mi--; mi>=0; mi--) {
182 		mem = &idev->info->mem[mi];
183 		kobject_unregister(&mem->kobj);
184 	}
185 	kset_unregister(&idev->map_attr_kset); /* Needed ? */
186 err_remove_group:
187 	sysfs_remove_group(&idev->dev->kobj, &uio_attr_grp);
188 err_group:
189 	dev_err(idev->dev, "error creating sysfs files (%d)\n", ret);
190 	return ret;
191 }
192 
193 static void uio_dev_del_attributes(struct uio_device *idev)
194 {
195 	int mi;
196 	struct uio_mem *mem;
197 	for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
198 		mem = &idev->info->mem[mi];
199 		if (mem->size == 0)
200 			break;
201 		kobject_unregister(&mem->kobj);
202 	}
203 	kset_unregister(&idev->map_attr_kset);
204 	sysfs_remove_group(&idev->dev->kobj, &uio_attr_grp);
205 }
206 
207 static int uio_get_minor(struct uio_device *idev)
208 {
209 	static DEFINE_MUTEX(minor_lock);
210 	int retval = -ENOMEM;
211 	int id;
212 
213 	mutex_lock(&minor_lock);
214 	if (idr_pre_get(&uio_idr, GFP_KERNEL) == 0)
215 		goto exit;
216 
217 	retval = idr_get_new(&uio_idr, idev, &id);
218 	if (retval < 0) {
219 		if (retval == -EAGAIN)
220 			retval = -ENOMEM;
221 		goto exit;
222 	}
223 	idev->minor = id & MAX_ID_MASK;
224 exit:
225 	mutex_unlock(&minor_lock);
226 	return retval;
227 }
228 
229 static void uio_free_minor(struct uio_device *idev)
230 {
231 	idr_remove(&uio_idr, idev->minor);
232 }
233 
234 /**
235  * uio_event_notify - trigger an interrupt event
236  * @info: UIO device capabilities
237  */
238 void uio_event_notify(struct uio_info *info)
239 {
240 	struct uio_device *idev = info->uio_dev;
241 
242 	atomic_inc(&idev->event);
243 	wake_up_interruptible(&idev->wait);
244 	kill_fasync(&idev->async_queue, SIGIO, POLL_IN);
245 }
246 EXPORT_SYMBOL_GPL(uio_event_notify);
247 
248 /**
249  * uio_interrupt - hardware interrupt handler
250  * @irq: IRQ number, can be UIO_IRQ_CYCLIC for cyclic timer
251  * @dev_id: Pointer to the devices uio_device structure
252  */
253 static irqreturn_t uio_interrupt(int irq, void *dev_id)
254 {
255 	struct uio_device *idev = (struct uio_device *)dev_id;
256 	irqreturn_t ret = idev->info->handler(irq, idev->info);
257 
258 	if (ret == IRQ_HANDLED)
259 		uio_event_notify(idev->info);
260 
261 	return ret;
262 }
263 
264 struct uio_listener {
265 	struct uio_device *dev;
266 	s32 event_count;
267 };
268 
269 static int uio_open(struct inode *inode, struct file *filep)
270 {
271 	struct uio_device *idev;
272 	struct uio_listener *listener;
273 	int ret = 0;
274 
275 	idev = idr_find(&uio_idr, iminor(inode));
276 	if (!idev)
277 		return -ENODEV;
278 
279 	listener = kmalloc(sizeof(*listener), GFP_KERNEL);
280 	if (!listener)
281 		return -ENOMEM;
282 
283 	listener->dev = idev;
284 	listener->event_count = atomic_read(&idev->event);
285 	filep->private_data = listener;
286 
287 	if (idev->info->open) {
288 		if (!try_module_get(idev->owner))
289 			return -ENODEV;
290 		ret = idev->info->open(idev->info, inode);
291 		module_put(idev->owner);
292 	}
293 
294 	if (ret)
295 		kfree(listener);
296 
297 	return ret;
298 }
299 
300 static int uio_fasync(int fd, struct file *filep, int on)
301 {
302 	struct uio_listener *listener = filep->private_data;
303 	struct uio_device *idev = listener->dev;
304 
305 	return fasync_helper(fd, filep, on, &idev->async_queue);
306 }
307 
308 static int uio_release(struct inode *inode, struct file *filep)
309 {
310 	int ret = 0;
311 	struct uio_listener *listener = filep->private_data;
312 	struct uio_device *idev = listener->dev;
313 
314 	if (idev->info->release) {
315 		if (!try_module_get(idev->owner))
316 			return -ENODEV;
317 		ret = idev->info->release(idev->info, inode);
318 		module_put(idev->owner);
319 	}
320 	if (filep->f_flags & FASYNC)
321 		ret = uio_fasync(-1, filep, 0);
322 	kfree(listener);
323 	return ret;
324 }
325 
326 static unsigned int uio_poll(struct file *filep, poll_table *wait)
327 {
328 	struct uio_listener *listener = filep->private_data;
329 	struct uio_device *idev = listener->dev;
330 
331 	if (idev->info->irq == UIO_IRQ_NONE)
332 		return -EIO;
333 
334 	poll_wait(filep, &idev->wait, wait);
335 	if (listener->event_count != atomic_read(&idev->event))
336 		return POLLIN | POLLRDNORM;
337 	return 0;
338 }
339 
340 static ssize_t uio_read(struct file *filep, char __user *buf,
341 			size_t count, loff_t *ppos)
342 {
343 	struct uio_listener *listener = filep->private_data;
344 	struct uio_device *idev = listener->dev;
345 	DECLARE_WAITQUEUE(wait, current);
346 	ssize_t retval;
347 	s32 event_count;
348 
349 	if (idev->info->irq == UIO_IRQ_NONE)
350 		return -EIO;
351 
352 	if (count != sizeof(s32))
353 		return -EINVAL;
354 
355 	add_wait_queue(&idev->wait, &wait);
356 
357 	do {
358 		set_current_state(TASK_INTERRUPTIBLE);
359 
360 		event_count = atomic_read(&idev->event);
361 		if (event_count != listener->event_count) {
362 			if (copy_to_user(buf, &event_count, count))
363 				retval = -EFAULT;
364 			else {
365 				listener->event_count = event_count;
366 				retval = count;
367 			}
368 			break;
369 		}
370 
371 		if (filep->f_flags & O_NONBLOCK) {
372 			retval = -EAGAIN;
373 			break;
374 		}
375 
376 		if (signal_pending(current)) {
377 			retval = -ERESTARTSYS;
378 			break;
379 		}
380 		schedule();
381 	} while (1);
382 
383 	__set_current_state(TASK_RUNNING);
384 	remove_wait_queue(&idev->wait, &wait);
385 
386 	return retval;
387 }
388 
389 static int uio_find_mem_index(struct vm_area_struct *vma)
390 {
391 	int mi;
392 	struct uio_device *idev = vma->vm_private_data;
393 
394 	for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
395 		if (idev->info->mem[mi].size == 0)
396 			return -1;
397 		if (vma->vm_pgoff == mi)
398 			return mi;
399 	}
400 	return -1;
401 }
402 
403 static void uio_vma_open(struct vm_area_struct *vma)
404 {
405 	struct uio_device *idev = vma->vm_private_data;
406 	idev->vma_count++;
407 }
408 
409 static void uio_vma_close(struct vm_area_struct *vma)
410 {
411 	struct uio_device *idev = vma->vm_private_data;
412 	idev->vma_count--;
413 }
414 
415 static struct page *uio_vma_nopage(struct vm_area_struct *vma,
416 				   unsigned long address, int *type)
417 {
418 	struct uio_device *idev = vma->vm_private_data;
419 	struct page* page = NOPAGE_SIGBUS;
420 
421 	int mi = uio_find_mem_index(vma);
422 	if (mi < 0)
423 		return page;
424 
425 	if (idev->info->mem[mi].memtype == UIO_MEM_LOGICAL)
426 		page = virt_to_page(idev->info->mem[mi].addr);
427 	else
428 		page = vmalloc_to_page((void*)idev->info->mem[mi].addr);
429 	get_page(page);
430 	if (type)
431 		*type = VM_FAULT_MINOR;
432 	return page;
433 }
434 
435 static struct vm_operations_struct uio_vm_ops = {
436 	.open = uio_vma_open,
437 	.close = uio_vma_close,
438 	.nopage = uio_vma_nopage,
439 };
440 
441 static int uio_mmap_physical(struct vm_area_struct *vma)
442 {
443 	struct uio_device *idev = vma->vm_private_data;
444 	int mi = uio_find_mem_index(vma);
445 	if (mi < 0)
446 		return -EINVAL;
447 
448 	vma->vm_flags |= VM_IO | VM_RESERVED;
449 
450 	return remap_pfn_range(vma,
451 			       vma->vm_start,
452 			       idev->info->mem[mi].addr >> PAGE_SHIFT,
453 			       vma->vm_end - vma->vm_start,
454 			       vma->vm_page_prot);
455 }
456 
457 static int uio_mmap_logical(struct vm_area_struct *vma)
458 {
459 	vma->vm_flags |= VM_RESERVED;
460 	vma->vm_ops = &uio_vm_ops;
461 	uio_vma_open(vma);
462 	return 0;
463 }
464 
465 static int uio_mmap(struct file *filep, struct vm_area_struct *vma)
466 {
467 	struct uio_listener *listener = filep->private_data;
468 	struct uio_device *idev = listener->dev;
469 	int mi;
470 	unsigned long requested_pages, actual_pages;
471 	int ret = 0;
472 
473 	if (vma->vm_end < vma->vm_start)
474 		return -EINVAL;
475 
476 	vma->vm_private_data = idev;
477 
478 	mi = uio_find_mem_index(vma);
479 	if (mi < 0)
480 		return -EINVAL;
481 
482 	requested_pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
483 	actual_pages = (idev->info->mem[mi].size + PAGE_SIZE -1) >> PAGE_SHIFT;
484 	if (requested_pages > actual_pages)
485 		return -EINVAL;
486 
487 	if (idev->info->mmap) {
488 		if (!try_module_get(idev->owner))
489 			return -ENODEV;
490 		ret = idev->info->mmap(idev->info, vma);
491 		module_put(idev->owner);
492 		return ret;
493 	}
494 
495 	switch (idev->info->mem[mi].memtype) {
496 		case UIO_MEM_PHYS:
497 			return uio_mmap_physical(vma);
498 		case UIO_MEM_LOGICAL:
499 		case UIO_MEM_VIRTUAL:
500 			return uio_mmap_logical(vma);
501 		default:
502 			return -EINVAL;
503 	}
504 }
505 
506 static struct file_operations uio_fops = {
507 	.owner		= THIS_MODULE,
508 	.open		= uio_open,
509 	.release	= uio_release,
510 	.read		= uio_read,
511 	.mmap		= uio_mmap,
512 	.poll		= uio_poll,
513 	.fasync		= uio_fasync,
514 };
515 
516 static int uio_major_init(void)
517 {
518 	uio_major = register_chrdev(0, "uio", &uio_fops);
519 	if (uio_major < 0)
520 		return uio_major;
521 	return 0;
522 }
523 
524 static void uio_major_cleanup(void)
525 {
526 	unregister_chrdev(uio_major, "uio");
527 }
528 
529 static int init_uio_class(void)
530 {
531 	int ret = 0;
532 
533 	if (uio_class != NULL) {
534 		kref_get(&uio_class->kref);
535 		goto exit;
536 	}
537 
538 	/* This is the first time in here, set everything up properly */
539 	ret = uio_major_init();
540 	if (ret)
541 		goto exit;
542 
543 	uio_class = kzalloc(sizeof(*uio_class), GFP_KERNEL);
544 	if (!uio_class) {
545 		ret = -ENOMEM;
546 		goto err_kzalloc;
547 	}
548 
549 	kref_init(&uio_class->kref);
550 	uio_class->class = class_create(THIS_MODULE, "uio");
551 	if (IS_ERR(uio_class->class)) {
552 		ret = IS_ERR(uio_class->class);
553 		printk(KERN_ERR "class_create failed for uio\n");
554 		goto err_class_create;
555 	}
556 	return 0;
557 
558 err_class_create:
559 	kfree(uio_class);
560 	uio_class = NULL;
561 err_kzalloc:
562 	uio_major_cleanup();
563 exit:
564 	return ret;
565 }
566 
567 static void release_uio_class(struct kref *kref)
568 {
569 	/* Ok, we cheat as we know we only have one uio_class */
570 	class_destroy(uio_class->class);
571 	kfree(uio_class);
572 	uio_major_cleanup();
573 	uio_class = NULL;
574 }
575 
576 static void uio_class_destroy(void)
577 {
578 	if (uio_class)
579 		kref_put(&uio_class->kref, release_uio_class);
580 }
581 
582 /**
583  * uio_register_device - register a new userspace IO device
584  * @owner:	module that creates the new device
585  * @parent:	parent device
586  * @info:	UIO device capabilities
587  *
588  * returns zero on success or a negative error code.
589  */
590 int __uio_register_device(struct module *owner,
591 			  struct device *parent,
592 			  struct uio_info *info)
593 {
594 	struct uio_device *idev;
595 	int ret = 0;
596 
597 	if (!parent || !info || !info->name || !info->version)
598 		return -EINVAL;
599 
600 	info->uio_dev = NULL;
601 
602 	ret = init_uio_class();
603 	if (ret)
604 		return ret;
605 
606 	idev = kzalloc(sizeof(*idev), GFP_KERNEL);
607 	if (!idev) {
608 		ret = -ENOMEM;
609 		goto err_kzalloc;
610 	}
611 
612 	idev->owner = owner;
613 	idev->info = info;
614 	init_waitqueue_head(&idev->wait);
615 	atomic_set(&idev->event, 0);
616 
617 	ret = uio_get_minor(idev);
618 	if (ret)
619 		goto err_get_minor;
620 
621 	idev->dev = device_create(uio_class->class, parent,
622 				  MKDEV(uio_major, idev->minor),
623 				  "uio%d", idev->minor);
624 	if (IS_ERR(idev->dev)) {
625 		printk(KERN_ERR "UIO: device register failed\n");
626 		ret = PTR_ERR(idev->dev);
627 		goto err_device_create;
628 	}
629 	dev_set_drvdata(idev->dev, idev);
630 
631 	ret = uio_dev_add_attributes(idev);
632 	if (ret)
633 		goto err_uio_dev_add_attributes;
634 
635 	info->uio_dev = idev;
636 
637 	if (idev->info->irq >= 0) {
638 		ret = request_irq(idev->info->irq, uio_interrupt,
639 				  idev->info->irq_flags, idev->info->name, idev);
640 		if (ret)
641 			goto err_request_irq;
642 	}
643 
644 	return 0;
645 
646 err_request_irq:
647 	uio_dev_del_attributes(idev);
648 err_uio_dev_add_attributes:
649 	device_destroy(uio_class->class, MKDEV(uio_major, idev->minor));
650 err_device_create:
651 	uio_free_minor(idev);
652 err_get_minor:
653 	kfree(idev);
654 err_kzalloc:
655 	uio_class_destroy();
656 	return ret;
657 }
658 EXPORT_SYMBOL_GPL(__uio_register_device);
659 
660 /**
661  * uio_unregister_device - unregister a industrial IO device
662  * @info:	UIO device capabilities
663  *
664  */
665 void uio_unregister_device(struct uio_info *info)
666 {
667 	struct uio_device *idev;
668 
669 	if (!info || !info->uio_dev)
670 		return;
671 
672 	idev = info->uio_dev;
673 
674 	uio_free_minor(idev);
675 
676 	if (info->irq >= 0)
677 		free_irq(info->irq, idev);
678 
679 	uio_dev_del_attributes(idev);
680 
681 	dev_set_drvdata(idev->dev, NULL);
682 	device_destroy(uio_class->class, MKDEV(uio_major, idev->minor));
683 	kfree(idev);
684 	uio_class_destroy();
685 
686 	return;
687 }
688 EXPORT_SYMBOL_GPL(uio_unregister_device);
689 
690 static int __init uio_init(void)
691 {
692 	return 0;
693 }
694 
695 static void __exit uio_exit(void)
696 {
697 }
698 
699 module_init(uio_init)
700 module_exit(uio_exit)
701 MODULE_LICENSE("GPL v2");
702