drivers/uio/uio.c

   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 kobject          *map_dir;
  38 };
  39
  40 static int uio_major;
  41 static DEFINE_IDR(uio_idr);
  42 static const 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 struct uio_map {
  55         struct kobject kobj;
  56         struct uio_mem *mem;
  57 };
  58 #define to_map(map) container_of(map, struct uio_map, kobj)
  59
  60
  61 static ssize_t map_attr_show(struct kobject *kobj, struct kobj_attribute *attr,
  62                              char *buf)
  63 {
  64         struct uio_map *map = to_map(kobj);
  65         struct uio_mem *mem = map->mem;
  66
  67         if (strncmp(attr->attr.name, "addr", 4) == 0)
  68                 return sprintf(buf, "0x%lx\n", mem->addr);
  69
  70         if (strncmp(attr->attr.name, "size", 4) == 0)
  71                 return sprintf(buf, "0x%lx\n", mem->size);
  72
  73         return -ENODEV;
  74 }
  75
  76 static struct kobj_attribute attr_attribute =
  77         __ATTR(addr, S_IRUGO, map_attr_show, NULL);
  78 static struct kobj_attribute size_attribute =
  79         __ATTR(size, S_IRUGO, map_attr_show, NULL);
  80
  81 static struct attribute *attrs[] = {
  82         &attr_attribute.attr,
  83         &size_attribute.attr,
  84         NULL,   /* need to NULL terminate the list of attributes */
  85 };
  86
  87 static void map_release(struct kobject *kobj)
  88 {
  89         struct uio_map *map = to_map(kobj);
  90         kfree(map);
  91 }
  92
  93 static struct kobj_type map_attr_type = {
  94         .release        = map_release,
  95         .default_attrs  = attrs,
  96 };
  97
  98 static ssize_t show_name(struct device *dev,
  99                          struct device_attribute *attr, char *buf)
 100 {
 101         struct uio_device *idev = dev_get_drvdata(dev);
 102         if (idev)
 103                 return sprintf(buf, "%s\n", idev->info->name);
 104         else
 105                 return -ENODEV;
 106 }
 107 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
 108
 109 static ssize_t show_version(struct device *dev,
 110                             struct device_attribute *attr, char *buf)
 111 {
 112         struct uio_device *idev = dev_get_drvdata(dev);
 113         if (idev)
 114                 return sprintf(buf, "%s\n", idev->info->version);
 115         else
 116                 return -ENODEV;
 117 }
 118 static DEVICE_ATTR(version, S_IRUGO, show_version, NULL);
 119
 120 static ssize_t show_event(struct device *dev,
 121                           struct device_attribute *attr, char *buf)
 122 {
 123         struct uio_device *idev = dev_get_drvdata(dev);
 124         if (idev)
 125                 return sprintf(buf, "%u\n",
 126                                 (unsigned int)atomic_read(&idev->event));
 127         else
 128                 return -ENODEV;
 129 }
 130 static DEVICE_ATTR(event, S_IRUGO, show_event, NULL);
 131
 132 static struct attribute *uio_attrs[] = {
 133         &dev_attr_name.attr,
 134         &dev_attr_version.attr,
 135         &dev_attr_event.attr,
 136         NULL,
 137 };
 138
 139 static struct attribute_group uio_attr_grp = {
 140         .attrs = uio_attrs,
 141 };
 142
 143 /*
 144  * device functions
 145  */
 146 static int uio_dev_add_attributes(struct uio_device *idev)
 147 {
 148         int ret;
 149         int mi;
 150         int map_found = 0;
 151         struct uio_mem *mem;
 152         struct uio_map *map;
 153
 154         ret = sysfs_create_group(&idev->dev->kobj, &uio_attr_grp);
 155         if (ret)
 156                 goto err_group;
 157
 158         for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
 159                 mem = &idev->info->mem[mi];
 160                 if (mem->size == 0)
 161                         break;
 162                 if (!map_found) {
 163                         map_found = 1;
 164                         idev->map_dir = kobject_create_and_add("maps",
 165                                                         &idev->dev->kobj);
 166                         if (!idev->map_dir)
 167                                 goto err;
 168                 }
 169                 map = kzalloc(sizeof(*map), GFP_KERNEL);
 170                 if (!map)
 171                         goto err;
 172                 kobject_init(&map->kobj, &map_attr_type);
 173                 map->mem = mem;
 174                 mem->map = map;
 175                 ret = kobject_add(&map->kobj, idev->map_dir, "map%d", mi);
 176                 if (ret)
 177                         goto err;
 178                 ret = kobject_uevent(&map->kobj, KOBJ_ADD);
 179                 if (ret)
 180                         goto err;
 181         }
 182
 183         return 0;
 184
 185 err:
 186         for (mi--; mi>=0; mi--) {
 187                 mem = &idev->info->mem[mi];
 188                 map = mem->map;
 189                 kobject_put(&map->kobj);
 190         }
 191         kobject_put(idev->map_dir);
 192         sysfs_remove_group(&idev->dev->kobj, &uio_attr_grp);
 193 err_group:
 194         dev_err(idev->dev, "error creating sysfs files (%d)\n", ret);
 195         return ret;
 196 }
 197
 198 static void uio_dev_del_attributes(struct uio_device *idev)
 199 {
 200         int mi;
 201         struct uio_mem *mem;
 202         for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
 203                 mem = &idev->info->mem[mi];
 204                 if (mem->size == 0)
 205                         break;
 206                 kobject_put(&mem->map->kobj);
 207         }
 208         kobject_put(idev->map_dir);
 209         sysfs_remove_group(&idev->dev->kobj, &uio_attr_grp);
 210 }
 211
 212 static int uio_get_minor(struct uio_device *idev)
 213 {
 214         static DEFINE_MUTEX(minor_lock);
 215         int retval = -ENOMEM;
 216         int id;
 217
 218         mutex_lock(&minor_lock);
 219         if (idr_pre_get(&uio_idr, GFP_KERNEL) == 0)
 220                 goto exit;
 221
 222         retval = idr_get_new(&uio_idr, idev, &id);
 223         if (retval < 0) {
 224                 if (retval == -EAGAIN)
 225                         retval = -ENOMEM;
 226                 goto exit;
 227         }
 228         idev->minor = id & MAX_ID_MASK;
 229 exit:
 230         mutex_unlock(&minor_lock);
 231         return retval;
 232 }
 233
 234 static void uio_free_minor(struct uio_device *idev)
 235 {
 236         idr_remove(&uio_idr, idev->minor);
 237 }
 238
 239 /**
 240  * uio_event_notify - trigger an interrupt event
 241  * @info: UIO device capabilities
 242  */
 243 void uio_event_notify(struct uio_info *info)
 244 {
 245         struct uio_device *idev = info->uio_dev;
 246
 247         atomic_inc(&idev->event);
 248         wake_up_interruptible(&idev->wait);
 249         kill_fasync(&idev->async_queue, SIGIO, POLL_IN);
 250 }
 251 EXPORT_SYMBOL_GPL(uio_event_notify);
 252
 253 /**
 254  * uio_interrupt - hardware interrupt handler
 255  * @irq: IRQ number, can be UIO_IRQ_CYCLIC for cyclic timer
 256  * @dev_id: Pointer to the devices uio_device structure
 257  */
 258 static irqreturn_t uio_interrupt(int irq, void *dev_id)
 259 {
 260         struct uio_device *idev = (struct uio_device *)dev_id;
 261         irqreturn_t ret = idev->info->handler(irq, idev->info);
 262
 263         if (ret == IRQ_HANDLED)
 264                 uio_event_notify(idev->info);
 265
 266         return ret;
 267 }
 268
 269 struct uio_listener {
 270         struct uio_device *dev;
 271         s32 event_count;
 272 };
 273
 274 static int uio_open(struct inode *inode, struct file *filep)
 275 {
 276         struct uio_device *idev;
 277         struct uio_listener *listener;
 278         int ret = 0;
 279
 280         idev = idr_find(&uio_idr, iminor(inode));
 281         if (!idev)
 282                 return -ENODEV;
 283
 284         listener = kmalloc(sizeof(*listener), GFP_KERNEL);
 285         if (!listener)
 286                 return -ENOMEM;
 287
 288         listener->dev = idev;
 289         listener->event_count = atomic_read(&idev->event);
 290         filep->private_data = listener;
 291
 292         if (idev->info->open) {
 293                 if (!try_module_get(idev->owner))
 294                         return -ENODEV;
 295                 ret = idev->info->open(idev->info, inode);
 296                 module_put(idev->owner);
 297         }
 298
 299         if (ret)
 300                 kfree(listener);
 301
 302         return ret;
 303 }
 304
 305 static int uio_fasync(int fd, struct file *filep, int on)
 306 {
 307         struct uio_listener *listener = filep->private_data;
 308         struct uio_device *idev = listener->dev;
 309
 310         return fasync_helper(fd, filep, on, &idev->async_queue);
 311 }
 312
 313 static int uio_release(struct inode *inode, struct file *filep)
 314 {
 315         int ret = 0;
 316         struct uio_listener *listener = filep->private_data;
 317         struct uio_device *idev = listener->dev;
 318
 319         if (idev->info->release) {
 320                 if (!try_module_get(idev->owner))
 321                         return -ENODEV;
 322                 ret = idev->info->release(idev->info, inode);
 323                 module_put(idev->owner);
 324         }
 325         if (filep->f_flags & FASYNC)
 326                 ret = uio_fasync(-1, filep, 0);
 327         kfree(listener);
 328         return ret;
 329 }
 330
 331 static unsigned int uio_poll(struct file *filep, poll_table *wait)
 332 {
 333         struct uio_listener *listener = filep->private_data;
 334         struct uio_device *idev = listener->dev;
 335
 336         if (idev->info->irq == UIO_IRQ_NONE)
 337                 return -EIO;
 338
 339         poll_wait(filep, &idev->wait, wait);
 340         if (listener->event_count != atomic_read(&idev->event))
 341                 return POLLIN | POLLRDNORM;
 342         return 0;
 343 }
 344
 345 static ssize_t uio_read(struct file *filep, char __user *buf,
 346                         size_t count, loff_t *ppos)
 347 {
 348         struct uio_listener *listener = filep->private_data;
 349         struct uio_device *idev = listener->dev;
 350         DECLARE_WAITQUEUE(wait, current);
 351         ssize_t retval;
 352         s32 event_count;
 353
 354         if (idev->info->irq == UIO_IRQ_NONE)
 355                 return -EIO;
 356
 357         if (count != sizeof(s32))
 358                 return -EINVAL;
 359
 360         add_wait_queue(&idev->wait, &wait);
 361
 362         do {
 363                 set_current_state(TASK_INTERRUPTIBLE);
 364
 365                 event_count = atomic_read(&idev->event);
 366                 if (event_count != listener->event_count) {
 367                         if (copy_to_user(buf, &event_count, count))
 368                                 retval = -EFAULT;
 369                         else {
 370                                 listener->event_count = event_count;
 371                                 retval = count;
 372                         }
 373                         break;
 374                 }
 375
 376                 if (filep->f_flags & O_NONBLOCK) {
 377                         retval = -EAGAIN;
 378                         break;
 379                 }
 380
 381                 if (signal_pending(current)) {
 382                         retval = -ERESTARTSYS;
 383                         break;
 384                 }
 385                 schedule();
 386         } while (1);
 387
 388         __set_current_state(TASK_RUNNING);
 389         remove_wait_queue(&idev->wait, &wait);
 390
 391         return retval;
 392 }
 393
 394 static int uio_find_mem_index(struct vm_area_struct *vma)
 395 {
 396         int mi;
 397         struct uio_device *idev = vma->vm_private_data;
 398
 399         for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
 400                 if (idev->info->mem[mi].size == 0)
 401                         return -1;
 402                 if (vma->vm_pgoff == mi)
 403                         return mi;
 404         }
 405         return -1;
 406 }
 407
 408 static void uio_vma_open(struct vm_area_struct *vma)
 409 {
 410         struct uio_device *idev = vma->vm_private_data;
 411         idev->vma_count++;
 412 }
 413
 414 static void uio_vma_close(struct vm_area_struct *vma)
 415 {
 416         struct uio_device *idev = vma->vm_private_data;
 417         idev->vma_count--;
 418 }
 419
 420 static struct page *uio_vma_nopage(struct vm_area_struct *vma,
 421                                    unsigned long address, int *type)
 422 {
 423         struct uio_device *idev = vma->vm_private_data;
 424         struct page* page = NOPAGE_SIGBUS;
 425
 426         int mi = uio_find_mem_index(vma);
 427         if (mi < 0)
 428                 return page;
 429
 430         if (idev->info->mem[mi].memtype == UIO_MEM_LOGICAL)
 431                 page = virt_to_page(idev->info->mem[mi].addr);
 432         else
 433                 page = vmalloc_to_page((void*)idev->info->mem[mi].addr);
 434         get_page(page);
 435         if (type)
 436                 *type = VM_FAULT_MINOR;
 437         return page;
 438 }
 439
 440 static struct vm_operations_struct uio_vm_ops = {
 441         .open = uio_vma_open,
 442         .close = uio_vma_close,
 443         .nopage = uio_vma_nopage,
 444 };
 445
 446 static int uio_mmap_physical(struct vm_area_struct *vma)
 447 {
 448         struct uio_device *idev = vma->vm_private_data;
 449         int mi = uio_find_mem_index(vma);
 450         if (mi < 0)
 451                 return -EINVAL;
 452
 453         vma->vm_flags |= VM_IO | VM_RESERVED;
 454
 455         return remap_pfn_range(vma,
 456                                vma->vm_start,
 457                                idev->info->mem[mi].addr >> PAGE_SHIFT,
 458                                vma->vm_end - vma->vm_start,
 459                                vma->vm_page_prot);
 460 }
 461
 462 static int uio_mmap_logical(struct vm_area_struct *vma)
 463 {
 464         vma->vm_flags |= VM_RESERVED;
 465         vma->vm_ops = &uio_vm_ops;
 466         uio_vma_open(vma);
 467         return 0;
 468 }
 469
 470 static int uio_mmap(struct file *filep, struct vm_area_struct *vma)
 471 {
 472         struct uio_listener *listener = filep->private_data;
 473         struct uio_device *idev = listener->dev;
 474         int mi;
 475         unsigned long requested_pages, actual_pages;
 476         int ret = 0;
 477
 478         if (vma->vm_end < vma->vm_start)
 479                 return -EINVAL;
 480
 481         vma->vm_private_data = idev;
 482
 483         mi = uio_find_mem_index(vma);
 484         if (mi < 0)
 485                 return -EINVAL;
 486
 487         requested_pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 488         actual_pages = (idev->info->mem[mi].size + PAGE_SIZE -1) >> PAGE_SHIFT;
 489         if (requested_pages > actual_pages)
 490                 return -EINVAL;
 491
 492         if (idev->info->mmap) {
 493                 if (!try_module_get(idev->owner))
 494                         return -ENODEV;
 495                 ret = idev->info->mmap(idev->info, vma);
 496                 module_put(idev->owner);
 497                 return ret;
 498         }
 499
 500         switch (idev->info->mem[mi].memtype) {
 501                 case UIO_MEM_PHYS:
 502                         return uio_mmap_physical(vma);
 503                 case UIO_MEM_LOGICAL:
 504                 case UIO_MEM_VIRTUAL:
 505                         return uio_mmap_logical(vma);
 506                 default:
 507                         return -EINVAL;
 508         }
 509 }
 510
 511 static const struct file_operations uio_fops = {
 512         .owner          = THIS_MODULE,
 513         .open           = uio_open,
 514         .release        = uio_release,
 515         .read           = uio_read,
 516         .mmap           = uio_mmap,
 517         .poll           = uio_poll,
 518         .fasync         = uio_fasync,
 519 };
 520
 521 static int uio_major_init(void)
 522 {
 523         uio_major = register_chrdev(0, "uio", &uio_fops);
 524         if (uio_major < 0)
 525                 return uio_major;
 526         return 0;
 527 }
 528
 529 static void uio_major_cleanup(void)
 530 {
 531         unregister_chrdev(uio_major, "uio");
 532 }
 533
 534 static int init_uio_class(void)
 535 {
 536         int ret = 0;
 537
 538         if (uio_class != NULL) {
 539                 kref_get(&uio_class->kref);
 540                 goto exit;
 541         }
 542
 543         /* This is the first time in here, set everything up properly */
 544         ret = uio_major_init();
 545         if (ret)
 546                 goto exit;
 547
 548         uio_class = kzalloc(sizeof(*uio_class), GFP_KERNEL);
 549         if (!uio_class) {
 550                 ret = -ENOMEM;
 551                 goto err_kzalloc;
 552         }
 553
 554         kref_init(&uio_class->kref);
 555         uio_class->class = class_create(THIS_MODULE, "uio");
 556         if (IS_ERR(uio_class->class)) {
 557                 ret = IS_ERR(uio_class->class);
 558                 printk(KERN_ERR "class_create failed for uio\n");
 559                 goto err_class_create;
 560         }
 561         return 0;
 562
 563 err_class_create:
 564         kfree(uio_class);
 565         uio_class = NULL;
 566 err_kzalloc:
 567         uio_major_cleanup();
 568 exit:
 569         return ret;
 570 }
 571
 572 static void release_uio_class(struct kref *kref)
 573 {
 574         /* Ok, we cheat as we know we only have one uio_class */
 575         class_destroy(uio_class->class);
 576         kfree(uio_class);
 577         uio_major_cleanup();
 578         uio_class = NULL;
 579 }
 580
 581 static void uio_class_destroy(void)
 582 {
 583         if (uio_class)
 584                 kref_put(&uio_class->kref, release_uio_class);
 585 }
 586
 587 /**
 588  * uio_register_device - register a new userspace IO device
 589  * @owner:      module that creates the new device
 590  * @parent:     parent device
 591  * @info:       UIO device capabilities
 592  *
 593  * returns zero on success or a negative error code.
 594  */
 595 int __uio_register_device(struct module *owner,
 596                           struct device *parent,
 597                           struct uio_info *info)
 598 {
 599         struct uio_device *idev;
 600         int ret = 0;
 601
 602         if (!parent || !info || !info->name || !info->version)
 603                 return -EINVAL;
 604
 605         info->uio_dev = NULL;
 606
 607         ret = init_uio_class();
 608         if (ret)
 609                 return ret;
 610
 611         idev = kzalloc(sizeof(*idev), GFP_KERNEL);
 612         if (!idev) {
 613                 ret = -ENOMEM;
 614                 goto err_kzalloc;
 615         }
 616
 617         idev->owner = owner;
 618         idev->info = info;
 619         init_waitqueue_head(&idev->wait);
 620         atomic_set(&idev->event, 0);
 621
 622         ret = uio_get_minor(idev);
 623         if (ret)
 624                 goto err_get_minor;
 625
 626         idev->dev = device_create(uio_class->class, parent,
 627                                   MKDEV(uio_major, idev->minor),
 628                                   "uio%d", idev->minor);
 629         if (IS_ERR(idev->dev)) {
 630                 printk(KERN_ERR "UIO: device register failed\n");
 631                 ret = PTR_ERR(idev->dev);
 632                 goto err_device_create;
 633         }
 634         dev_set_drvdata(idev->dev, idev);
 635
 636         ret = uio_dev_add_attributes(idev);
 637         if (ret)
 638                 goto err_uio_dev_add_attributes;
 639
 640         info->uio_dev = idev;
 641
 642         if (idev->info->irq >= 0) {
 643                 ret = request_irq(idev->info->irq, uio_interrupt,
 644                                   idev->info->irq_flags, idev->info->name, idev);
 645                 if (ret)
 646                         goto err_request_irq;
 647         }
 648
 649         return 0;
 650
 651 err_request_irq:
 652         uio_dev_del_attributes(idev);
 653 err_uio_dev_add_attributes:
 654         device_destroy(uio_class->class, MKDEV(uio_major, idev->minor));
 655 err_device_create:
 656         uio_free_minor(idev);
 657 err_get_minor:
 658         kfree(idev);
 659 err_kzalloc:
 660         uio_class_destroy();
 661         return ret;
 662 }
 663 EXPORT_SYMBOL_GPL(__uio_register_device);
 664
 665 /**
 666  * uio_unregister_device - unregister a industrial IO device
 667  * @info:       UIO device capabilities
 668  *
 669  */
 670 void uio_unregister_device(struct uio_info *info)
 671 {
 672         struct uio_device *idev;
 673
 674         if (!info || !info->uio_dev)
 675                 return;
 676
 677         idev = info->uio_dev;
 678
 679         uio_free_minor(idev);
 680
 681         if (info->irq >= 0)
 682                 free_irq(info->irq, idev);
 683
 684         uio_dev_del_attributes(idev);
 685
 686         dev_set_drvdata(idev->dev, NULL);
 687         device_destroy(uio_class->class, MKDEV(uio_major, idev->minor));
 688         kfree(idev);
 689         uio_class_destroy();
 690
 691         return;
 692 }
 693 EXPORT_SYMBOL_GPL(uio_unregister_device);
 694
 695 static int __init uio_init(void)
 696 {
 697         return 0;
 698 }
 699
 700 static void __exit uio_exit(void)
 701 {
 702 }
 703
 704 module_init(uio_init)
 705 module_exit(uio_exit)
 706 MODULE_LICENSE("GPL v2");