kernel/2.6.29.6-aldebaran-rt/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         struct kobject          *portio_dir;
  39 };
  40
  41 static int uio_major;
  42 static DEFINE_IDR(uio_idr);
  43 static const struct file_operations uio_fops;
  44
  45 /* UIO class infrastructure */
  46 static struct uio_class {
  47         struct kref kref;
  48         struct class *class;
  49 } *uio_class;
  50
  51 /* Protect idr accesses */
  52 static DEFINE_MUTEX(minor_lock);
  53
  54 /*
  55  * attributes
  56  */
  57
  58 struct uio_map {
  59         struct kobject kobj;
  60         struct uio_mem *mem;
  61 };
  62 #define to_map(map) container_of(map, struct uio_map, kobj)
  63
  64 static ssize_t map_addr_show(struct uio_mem *mem, char *buf)
  65 {
  66         return sprintf(buf, "0x%lx\n", mem->addr);
  67 }
  68
  69 static ssize_t map_size_show(struct uio_mem *mem, char *buf)
  70 {
  71         return sprintf(buf, "0x%lx\n", mem->size);
  72 }
  73
  74 static ssize_t map_offset_show(struct uio_mem *mem, char *buf)
  75 {
  76         return sprintf(buf, "0x%lx\n", mem->addr & ~PAGE_MASK);
  77 }
  78
  79 struct map_sysfs_entry {
  80         struct attribute attr;
  81         ssize_t (*show)(struct uio_mem *, char *);
  82         ssize_t (*store)(struct uio_mem *, const char *, size_t);
  83 };
  84
  85 static struct map_sysfs_entry addr_attribute =
  86         __ATTR(addr, S_IRUGO, map_addr_show, NULL);
  87 static struct map_sysfs_entry size_attribute =
  88         __ATTR(size, S_IRUGO, map_size_show, NULL);
  89 static struct map_sysfs_entry offset_attribute =
  90         __ATTR(offset, S_IRUGO, map_offset_show, NULL);
  91
  92 static struct attribute *attrs[] = {
  93         &addr_attribute.attr,
  94         &size_attribute.attr,
  95         &offset_attribute.attr,
  96         NULL,   /* need to NULL terminate the list of attributes */
  97 };
  98
  99 static void map_release(struct kobject *kobj)
 100 {
 101         struct uio_map *map = to_map(kobj);
 102         kfree(map);
 103 }
 104
 105 static ssize_t map_type_show(struct kobject *kobj, struct attribute *attr,
 106                              char *buf)
 107 {
 108         struct uio_map *map = to_map(kobj);
 109         struct uio_mem *mem = map->mem;
 110         struct map_sysfs_entry *entry;
 111
 112         entry = container_of(attr, struct map_sysfs_entry, attr);
 113
 114         if (!entry->show)
 115                 return -EIO;
 116
 117         return entry->show(mem, buf);
 118 }
 119
 120 static struct sysfs_ops map_sysfs_ops = {
 121         .show = map_type_show,
 122 };
 123
 124 static struct kobj_type map_attr_type = {
 125         .release        = map_release,
 126         .sysfs_ops      = &map_sysfs_ops,
 127         .default_attrs  = attrs,
 128 };
 129
 130 struct uio_portio {
 131         struct kobject kobj;
 132         struct uio_port *port;
 133 };
 134 #define to_portio(portio) container_of(portio, struct uio_portio, kobj)
 135
 136 static ssize_t portio_start_show(struct uio_port *port, char *buf)
 137 {
 138         return sprintf(buf, "0x%lx\n", port->start);
 139 }
 140
 141 static ssize_t portio_size_show(struct uio_port *port, char *buf)
 142 {
 143         return sprintf(buf, "0x%lx\n", port->size);
 144 }
 145
 146 static ssize_t portio_porttype_show(struct uio_port *port, char *buf)
 147 {
 148         const char *porttypes[] = {"none", "x86", "gpio", "other"};
 149
 150         if ((port->porttype < 0) || (port->porttype > UIO_PORT_OTHER))
 151                 return -EINVAL;
 152
 153         return sprintf(buf, "port_%s\n", porttypes[port->porttype]);
 154 }
 155
 156 struct portio_sysfs_entry {
 157         struct attribute attr;
 158         ssize_t (*show)(struct uio_port *, char *);
 159         ssize_t (*store)(struct uio_port *, const char *, size_t);
 160 };
 161
 162 static struct portio_sysfs_entry portio_start_attribute =
 163         __ATTR(start, S_IRUGO, portio_start_show, NULL);
 164 static struct portio_sysfs_entry portio_size_attribute =
 165         __ATTR(size, S_IRUGO, portio_size_show, NULL);
 166 static struct portio_sysfs_entry portio_porttype_attribute =
 167         __ATTR(porttype, S_IRUGO, portio_porttype_show, NULL);
 168
 169 static struct attribute *portio_attrs[] = {
 170         &portio_start_attribute.attr,
 171         &portio_size_attribute.attr,
 172         &portio_porttype_attribute.attr,
 173         NULL,
 174 };
 175
 176 static void portio_release(struct kobject *kobj)
 177 {
 178         struct uio_portio *portio = to_portio(kobj);
 179         kfree(portio);
 180 }
 181
 182 static ssize_t portio_type_show(struct kobject *kobj, struct attribute *attr,
 183                              char *buf)
 184 {
 185         struct uio_portio *portio = to_portio(kobj);
 186         struct uio_port *port = portio->port;
 187         struct portio_sysfs_entry *entry;
 188
 189         entry = container_of(attr, struct portio_sysfs_entry, attr);
 190
 191         if (!entry->show)
 192                 return -EIO;
 193
 194         return entry->show(port, buf);
 195 }
 196
 197 static struct sysfs_ops portio_sysfs_ops = {
 198         .show = portio_type_show,
 199 };
 200
 201 static struct kobj_type portio_attr_type = {
 202         .release        = portio_release,
 203         .sysfs_ops      = &portio_sysfs_ops,
 204         .default_attrs  = portio_attrs,
 205 };
 206
 207 static ssize_t show_name(struct device *dev,
 208                          struct device_attribute *attr, char *buf)
 209 {
 210         struct uio_device *idev = dev_get_drvdata(dev);
 211         if (idev)
 212                 return sprintf(buf, "%s\n", idev->info->name);
 213         else
 214                 return -ENODEV;
 215 }
 216 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
 217
 218 static ssize_t show_version(struct device *dev,
 219                             struct device_attribute *attr, char *buf)
 220 {
 221         struct uio_device *idev = dev_get_drvdata(dev);
 222         if (idev)
 223                 return sprintf(buf, "%s\n", idev->info->version);
 224         else
 225                 return -ENODEV;
 226 }
 227 static DEVICE_ATTR(version, S_IRUGO, show_version, NULL);
 228
 229 static ssize_t show_event(struct device *dev,
 230                           struct device_attribute *attr, char *buf)
 231 {
 232         struct uio_device *idev = dev_get_drvdata(dev);
 233         if (idev)
 234                 return sprintf(buf, "%u\n",
 235                                 (unsigned int)atomic_read(&idev->event));
 236         else
 237                 return -ENODEV;
 238 }
 239 static DEVICE_ATTR(event, S_IRUGO, show_event, NULL);
 240
 241 static struct attribute *uio_attrs[] = {
 242         &dev_attr_name.attr,
 243         &dev_attr_version.attr,
 244         &dev_attr_event.attr,
 245         NULL,
 246 };
 247
 248 static struct attribute_group uio_attr_grp = {
 249         .attrs = uio_attrs,
 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         ret = sysfs_create_group(&idev->dev->kobj, &uio_attr_grp);
 267         if (ret)
 268                 goto err_group;
 269
 270         for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
 271                 mem = &idev->info->mem[mi];
 272                 if (mem->size == 0)
 273                         break;
 274                 if (!map_found) {
 275                         map_found = 1;
 276                         idev->map_dir = kobject_create_and_add("maps",
 277                                                         &idev->dev->kobj);
 278                         if (!idev->map_dir)
 279                                 goto err_map;
 280                 }
 281                 map = kzalloc(sizeof(*map), GFP_KERNEL);
 282                 if (!map)
 283                         goto err_map;
 284                 kobject_init(&map->kobj, &map_attr_type);
 285                 map->mem = mem;
 286                 mem->map = map;
 287                 ret = kobject_add(&map->kobj, idev->map_dir, "map%d", mi);
 288                 if (ret)
 289                         goto err_map;
 290                 ret = kobject_uevent(&map->kobj, KOBJ_ADD);
 291                 if (ret)
 292                         goto err_map;
 293         }
 294
 295         for (pi = 0; pi < MAX_UIO_PORT_REGIONS; pi++) {
 296                 port = &idev->info->port[pi];
 297                 if (port->size == 0)
 298                         break;
 299                 if (!portio_found) {
 300                         portio_found = 1;
 301                         idev->portio_dir = kobject_create_and_add("portio",
 302                                                         &idev->dev->kobj);
 303                         if (!idev->portio_dir)
 304                                 goto err_portio;
 305                 }
 306                 portio = kzalloc(sizeof(*portio), GFP_KERNEL);
 307                 if (!portio)
 308                         goto err_portio;
 309                 kobject_init(&portio->kobj, &portio_attr_type);
 310                 portio->port = port;
 311                 port->portio = portio;
 312                 ret = kobject_add(&portio->kobj, idev->portio_dir,
 313                                                         "port%d", pi);
 314                 if (ret)
 315                         goto err_portio;
 316                 ret = kobject_uevent(&portio->kobj, KOBJ_ADD);
 317                 if (ret)
 318                         goto err_portio;
 319         }
 320
 321         return 0;
 322
 323 err_portio:
 324         for (pi--; pi >= 0; pi--) {
 325                 port = &idev->info->port[pi];
 326                 portio = port->portio;
 327                 kobject_put(&portio->kobj);
 328         }
 329         kobject_put(idev->portio_dir);
 330 err_map:
 331         for (mi--; 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         sysfs_remove_group(&idev->dev->kobj, &uio_attr_grp);
 338 err_group:
 339         dev_err(idev->dev, "error creating sysfs files (%d)\n", ret);
 340         return ret;
 341 }
 342
 343 static void uio_dev_del_attributes(struct uio_device *idev)
 344 {
 345         int i;
 346         struct uio_mem *mem;
 347         struct uio_port *port;
 348
 349         for (i = 0; i < MAX_UIO_MAPS; i++) {
 350                 mem = &idev->info->mem[i];
 351                 if (mem->size == 0)
 352                         break;
 353                 kobject_put(&mem->map->kobj);
 354         }
 355         kobject_put(idev->map_dir);
 356
 357         for (i = 0; i < MAX_UIO_PORT_REGIONS; i++) {
 358                 port = &idev->info->port[i];
 359                 if (port->size == 0)
 360                         break;
 361                 kobject_put(&port->portio->kobj);
 362         }
 363         kobject_put(idev->portio_dir);
 364
 365         sysfs_remove_group(&idev->dev->kobj, &uio_attr_grp);
 366 }
 367
 368 static int uio_get_minor(struct uio_device *idev)
 369 {
 370         int retval = -ENOMEM;
 371         int id;
 372
 373         mutex_lock(&minor_lock);
 374         if (idr_pre_get(&uio_idr, GFP_KERNEL) == 0)
 375                 goto exit;
 376
 377         retval = idr_get_new(&uio_idr, idev, &id);
 378         if (retval < 0) {
 379                 if (retval == -EAGAIN)
 380                         retval = -ENOMEM;
 381                 goto exit;
 382         }
 383         idev->minor = id & MAX_ID_MASK;
 384 exit:
 385         mutex_unlock(&minor_lock);
 386         return retval;
 387 }
 388
 389 static void uio_free_minor(struct uio_device *idev)
 390 {
 391         mutex_lock(&minor_lock);
 392         idr_remove(&uio_idr, idev->minor);
 393         mutex_unlock(&minor_lock);
 394 }
 395
 396 /**
 397  * uio_event_notify - trigger an interrupt event
 398  * @info: UIO device capabilities
 399  */
 400 void uio_event_notify(struct uio_info *info)
 401 {
 402         struct uio_device *idev = info->uio_dev;
 403
 404         atomic_inc(&idev->event);
 405         wake_up_interruptible(&idev->wait);
 406         kill_fasync(&idev->async_queue, SIGIO, POLL_IN);
 407 }
 408 EXPORT_SYMBOL_GPL(uio_event_notify);
 409
 410 /**
 411  * uio_interrupt - hardware interrupt handler
 412  * @irq: IRQ number, can be UIO_IRQ_CYCLIC for cyclic timer
 413  * @dev_id: Pointer to the devices uio_device structure
 414  */
 415 static irqreturn_t uio_interrupt(int irq, void *dev_id)
 416 {
 417         struct uio_device *idev = (struct uio_device *)dev_id;
 418         irqreturn_t ret = idev->info->handler(irq, idev->info);
 419
 420         if (ret == IRQ_HANDLED)
 421                 uio_event_notify(idev->info);
 422
 423         return ret;
 424 }
 425
 426 struct uio_listener {
 427         struct uio_device *dev;
 428         s32 event_count;
 429 };
 430
 431 static int uio_open(struct inode *inode, struct file *filep)
 432 {
 433         struct uio_device *idev;
 434         struct uio_listener *listener;
 435         int ret = 0;
 436
 437         mutex_lock(&minor_lock);
 438         idev = idr_find(&uio_idr, iminor(inode));
 439         mutex_unlock(&minor_lock);
 440         if (!idev) {
 441                 ret = -ENODEV;
 442                 goto out;
 443         }
 444
 445         if (!try_module_get(idev->owner)) {
 446                 ret = -ENODEV;
 447                 goto out;
 448         }
 449
 450         listener = kmalloc(sizeof(*listener), GFP_KERNEL);
 451         if (!listener) {
 452                 ret = -ENOMEM;
 453                 goto err_alloc_listener;
 454         }
 455
 456         listener->dev = idev;
 457         listener->event_count = atomic_read(&idev->event);
 458         filep->private_data = listener;
 459
 460         if (idev->info->open) {
 461                 ret = idev->info->open(idev->info, inode);
 462                 if (ret)
 463                         goto err_infoopen;
 464         }
 465         return 0;
 466
 467 err_infoopen:
 468         kfree(listener);
 469
 470 err_alloc_listener:
 471         module_put(idev->owner);
 472
 473 out:
 474         return ret;
 475 }
 476
 477 static int uio_fasync(int fd, struct file *filep, int on)
 478 {
 479         struct uio_listener *listener = filep->private_data;
 480         struct uio_device *idev = listener->dev;
 481
 482         return fasync_helper(fd, filep, on, &idev->async_queue);
 483 }
 484
 485 static int uio_release(struct inode *inode, struct file *filep)
 486 {
 487         int ret = 0;
 488         struct uio_listener *listener = filep->private_data;
 489         struct uio_device *idev = listener->dev;
 490
 491         if (idev->info->release)
 492                 ret = idev->info->release(idev->info, inode);
 493
 494         module_put(idev->owner);
 495         kfree(listener);
 496         return ret;
 497 }
 498
 499 static unsigned int uio_poll(struct file *filep, poll_table *wait)
 500 {
 501         struct uio_listener *listener = filep->private_data;
 502         struct uio_device *idev = listener->dev;
 503
 504         if (idev->info->irq == UIO_IRQ_NONE)
 505                 return -EIO;
 506
 507         poll_wait(filep, &idev->wait, wait);
 508         if (listener->event_count != atomic_read(&idev->event))
 509                 return POLLIN | POLLRDNORM;
 510         return 0;
 511 }
 512
 513 static ssize_t uio_read(struct file *filep, char __user *buf,
 514                         size_t count, loff_t *ppos)
 515 {
 516         struct uio_listener *listener = filep->private_data;
 517         struct uio_device *idev = listener->dev;
 518         DECLARE_WAITQUEUE(wait, current);
 519         ssize_t retval;
 520         s32 event_count;
 521
 522         if (idev->info->irq == UIO_IRQ_NONE)
 523                 return -EIO;
 524
 525         if (count != sizeof(s32))
 526                 return -EINVAL;
 527
 528         add_wait_queue(&idev->wait, &wait);
 529
 530         do {
 531                 set_current_state(TASK_INTERRUPTIBLE);
 532
 533                 event_count = atomic_read(&idev->event);
 534                 if (event_count != listener->event_count) {
 535                         if (copy_to_user(buf, &event_count, count))
 536                                 retval = -EFAULT;
 537                         else {
 538                                 listener->event_count = event_count;
 539                                 retval = count;
 540                         }
 541                         break;
 542                 }
 543
 544                 if (filep->f_flags & O_NONBLOCK) {
 545                         retval = -EAGAIN;
 546                         break;
 547                 }
 548
 549                 if (signal_pending(current)) {
 550                         retval = -ERESTARTSYS;
 551                         break;
 552                 }
 553                 schedule();
 554         } while (1);
 555
 556         __set_current_state(TASK_RUNNING);
 557         remove_wait_queue(&idev->wait, &wait);
 558
 559         return retval;
 560 }
 561
 562 static ssize_t uio_write(struct file *filep, const char __user *buf,
 563                         size_t count, loff_t *ppos)
 564 {
 565         struct uio_listener *listener = filep->private_data;
 566         struct uio_device *idev = listener->dev;
 567         ssize_t retval;
 568         s32 irq_on;
 569
 570         if (idev->info->irq == UIO_IRQ_NONE)
 571                 return -EIO;
 572
 573         if (count != sizeof(s32))
 574                 return -EINVAL;
 575
 576         if (!idev->info->irqcontrol)
 577                 return -ENOSYS;
 578
 579         if (copy_from_user(&irq_on, buf, count))
 580                 return -EFAULT;
 581
 582         retval = idev->info->irqcontrol(idev->info, irq_on);
 583
 584         return retval ? retval : sizeof(s32);
 585 }
 586
 587 static int uio_find_mem_index(struct vm_area_struct *vma)
 588 {
 589         int mi;
 590         struct uio_device *idev = vma->vm_private_data;
 591
 592         for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
 593                 if (idev->info->mem[mi].size == 0)
 594                         return -1;
 595                 if (vma->vm_pgoff == mi)
 596                         return mi;
 597         }
 598         return -1;
 599 }
 600
 601 static void uio_vma_open(struct vm_area_struct *vma)
 602 {
 603         struct uio_device *idev = vma->vm_private_data;
 604         idev->vma_count++;
 605 }
 606
 607 static void uio_vma_close(struct vm_area_struct *vma)
 608 {
 609         struct uio_device *idev = vma->vm_private_data;
 610         idev->vma_count--;
 611 }
 612
 613 static int uio_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 614 {
 615         struct uio_device *idev = vma->vm_private_data;
 616         struct page *page;
 617         unsigned long offset;
 618
 619         int mi = uio_find_mem_index(vma);
 620         if (mi < 0)
 621                 return VM_FAULT_SIGBUS;
 622
 623         /*
 624          * We need to subtract mi because userspace uses offset = N*PAGE_SIZE
 625          * to use mem[N].
 626          */
 627         offset = (vmf->pgoff - mi) << PAGE_SHIFT;
 628
 629         if (idev->info->mem[mi].memtype == UIO_MEM_LOGICAL)
 630                 page = virt_to_page(idev->info->mem[mi].addr + offset);
 631         else
 632                 page = vmalloc_to_page((void *)idev->info->mem[mi].addr
 633                                                         + offset);
 634         get_page(page);
 635         vmf->page = page;
 636         return 0;
 637 }
 638
 639 static struct vm_operations_struct uio_vm_ops = {
 640         .open = uio_vma_open,
 641         .close = uio_vma_close,
 642         .fault = uio_vma_fault,
 643 };
 644
 645 static int uio_mmap_physical(struct vm_area_struct *vma)
 646 {
 647         struct uio_device *idev = vma->vm_private_data;
 648         int mi = uio_find_mem_index(vma);
 649         if (mi < 0)
 650                 return -EINVAL;
 651
 652         vma->vm_flags |= VM_IO | VM_RESERVED;
 653
 654         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 655
 656         return remap_pfn_range(vma,
 657                                vma->vm_start,
 658                                idev->info->mem[mi].addr >> PAGE_SHIFT,
 659                                vma->vm_end - vma->vm_start,
 660                                vma->vm_page_prot);
 661 }
 662
 663 static int uio_mmap_logical(struct vm_area_struct *vma)
 664 {
 665         vma->vm_flags |= VM_RESERVED;
 666         vma->vm_ops = &uio_vm_ops;
 667         uio_vma_open(vma);
 668         return 0;
 669 }
 670
 671 static int uio_mmap(struct file *filep, struct vm_area_struct *vma)
 672 {
 673         struct uio_listener *listener = filep->private_data;
 674         struct uio_device *idev = listener->dev;
 675         int mi;
 676         unsigned long requested_pages, actual_pages;
 677         int ret = 0;
 678
 679         if (vma->vm_end < vma->vm_start)
 680                 return -EINVAL;
 681
 682         vma->vm_private_data = idev;
 683
 684         mi = uio_find_mem_index(vma);
 685         if (mi < 0)
 686                 return -EINVAL;
 687
 688         requested_pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 689         actual_pages = (idev->info->mem[mi].size + PAGE_SIZE -1) >> PAGE_SHIFT;
 690         if (requested_pages > actual_pages)
 691                 return -EINVAL;
 692
 693         if (idev->info->mmap) {
 694                 ret = idev->info->mmap(idev->info, vma);
 695                 return ret;
 696         }
 697
 698         switch (idev->info->mem[mi].memtype) {
 699                 case UIO_MEM_PHYS:
 700                         return uio_mmap_physical(vma);
 701                 case UIO_MEM_LOGICAL:
 702                 case UIO_MEM_VIRTUAL:
 703                         return uio_mmap_logical(vma);
 704                 default:
 705                         return -EINVAL;
 706         }
 707 }
 708
 709 static const struct file_operations uio_fops = {
 710         .owner          = THIS_MODULE,
 711         .open           = uio_open,
 712         .release        = uio_release,
 713         .read           = uio_read,
 714         .write          = uio_write,
 715         .mmap           = uio_mmap,
 716         .poll           = uio_poll,
 717         .fasync         = uio_fasync,
 718 };
 719
 720 static int uio_major_init(void)
 721 {
 722         uio_major = register_chrdev(0, "uio", &uio_fops);
 723         if (uio_major < 0)
 724                 return uio_major;
 725         return 0;
 726 }
 727
 728 static void uio_major_cleanup(void)
 729 {
 730         unregister_chrdev(uio_major, "uio");
 731 }
 732
 733 static int init_uio_class(void)
 734 {
 735         int ret = 0;
 736
 737         if (uio_class != NULL) {
 738                 kref_get(&uio_class->kref);
 739                 goto exit;
 740         }
 741
 742         /* This is the first time in here, set everything up properly */
 743         ret = uio_major_init();
 744         if (ret)
 745                 goto exit;
 746
 747         uio_class = kzalloc(sizeof(*uio_class), GFP_KERNEL);
 748         if (!uio_class) {
 749                 ret = -ENOMEM;
 750                 goto err_kzalloc;
 751         }
 752
 753         kref_init(&uio_class->kref);
 754         uio_class->class = class_create(THIS_MODULE, "uio");
 755         if (IS_ERR(uio_class->class)) {
 756                 ret = IS_ERR(uio_class->class);
 757                 printk(KERN_ERR "class_create failed for uio\n");
 758                 goto err_class_create;
 759         }
 760         return 0;
 761
 762 err_class_create:
 763         kfree(uio_class);
 764         uio_class = NULL;
 765 err_kzalloc:
 766         uio_major_cleanup();
 767 exit:
 768         return ret;
 769 }
 770
 771 static void release_uio_class(struct kref *kref)
 772 {
 773         /* Ok, we cheat as we know we only have one uio_class */
 774         class_destroy(uio_class->class);
 775         kfree(uio_class);
 776         uio_major_cleanup();
 777         uio_class = NULL;
 778 }
 779
 780 static void uio_class_destroy(void)
 781 {
 782         if (uio_class)
 783                 kref_put(&uio_class->kref, release_uio_class);
 784 }
 785
 786 /**
 787  * uio_register_device - register a new userspace IO device
 788  * @owner:      module that creates the new device
 789  * @parent:     parent device
 790  * @info:       UIO device capabilities
 791  *
 792  * returns zero on success or a negative error code.
 793  */
 794 int __uio_register_device(struct module *owner,
 795                           struct device *parent,
 796                           struct uio_info *info)
 797 {
 798         struct uio_device *idev;
 799         int ret = 0;
 800
 801         if (!parent || !info || !info->name || !info->version)
 802                 return -EINVAL;
 803
 804         info->uio_dev = NULL;
 805
 806         ret = init_uio_class();
 807         if (ret)
 808                 return ret;
 809
 810         idev = kzalloc(sizeof(*idev), GFP_KERNEL);
 811         if (!idev) {
 812                 ret = -ENOMEM;
 813                 goto err_kzalloc;
 814         }
 815
 816         idev->owner = owner;
 817         idev->info = info;
 818         init_waitqueue_head(&idev->wait);
 819         atomic_set(&idev->event, 0);
 820
 821         ret = uio_get_minor(idev);
 822         if (ret)
 823                 goto err_get_minor;
 824
 825         idev->dev = device_create(uio_class->class, parent,
 826                                   MKDEV(uio_major, idev->minor), idev,
 827                                   "uio%d", idev->minor);
 828         if (IS_ERR(idev->dev)) {
 829                 printk(KERN_ERR "UIO: device register failed\n");
 830                 ret = PTR_ERR(idev->dev);
 831                 goto err_device_create;
 832         }
 833
 834         ret = uio_dev_add_attributes(idev);
 835         if (ret)
 836                 goto err_uio_dev_add_attributes;
 837
 838         info->uio_dev = idev;
 839
 840         if (idev->info->irq >= 0) {
 841                 ret = request_irq(idev->info->irq, uio_interrupt,
 842                                   idev->info->irq_flags, idev->info->name, idev);
 843                 if (ret)
 844                         goto err_request_irq;
 845         }
 846
 847         return 0;
 848
 849 err_request_irq:
 850         uio_dev_del_attributes(idev);
 851 err_uio_dev_add_attributes:
 852         device_destroy(uio_class->class, MKDEV(uio_major, idev->minor));
 853 err_device_create:
 854         uio_free_minor(idev);
 855 err_get_minor:
 856         kfree(idev);
 857 err_kzalloc:
 858         uio_class_destroy();
 859         return ret;
 860 }
 861 EXPORT_SYMBOL_GPL(__uio_register_device);
 862
 863 /**
 864  * uio_unregister_device - unregister a industrial IO device
 865  * @info:       UIO device capabilities
 866  *
 867  */
 868 void uio_unregister_device(struct uio_info *info)
 869 {
 870         struct uio_device *idev;
 871
 872         if (!info || !info->uio_dev)
 873                 return;
 874
 875         idev = info->uio_dev;
 876
 877         uio_free_minor(idev);
 878
 879         if (info->irq >= 0)
 880                 free_irq(info->irq, idev);
 881
 882         uio_dev_del_attributes(idev);
 883
 884         dev_set_drvdata(idev->dev, NULL);
 885         device_destroy(uio_class->class, MKDEV(uio_major, idev->minor));
 886         kfree(idev);
 887         uio_class_destroy();
 888
 889         return;
 890 }
 891 EXPORT_SYMBOL_GPL(uio_unregister_device);
 892
 893 static int __init uio_init(void)
 894 {
 895         return 0;
 896 }
 897
 898 static void __exit uio_exit(void)
 899 {
 900 }
 901
 902 module_init(uio_init)
 903 module_exit(uio_exit)
 904 MODULE_LICENSE("GPL v2");