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@hansjkoch.de>
   7  * Copyright(C) 2006, Greg Kroah-Hartman <greg@kroah.com>
   8  *
   9  * Userspace IO
  10  *
  11  * Base Functions
  12  *
  13  * Licensed under the GPLv2 only.
  14  */
  15
  16 #include <linux/module.h>
  17 #include <linux/init.h>
  18 #include <linux/poll.h>
  19 #include <linux/device.h>
  20 #include <linux/slab.h>
  21 #include <linux/mm.h>
  22 #include <linux/idr.h>
  23 #include <linux/sched.h>
  24 #include <linux/string.h>
  25 #include <linux/kobject.h>
  26 #include <linux/cdev.h>
  27 #include <linux/uio_driver.h>
  28
  29 #define UIO_MAX_DEVICES         (1U << MINORBITS)
  30
  31 struct uio_device {
  32         struct module           *owner;
  33         struct device           *dev;
  34         int                     minor;
  35         atomic_t                event;
  36         struct fasync_struct    *async_queue;
  37         wait_queue_head_t       wait;
  38         int                     vma_count;
  39         struct uio_info         *info;
  40         struct kobject          *map_dir;
  41         struct kobject          *portio_dir;
  42 };
  43
  44 static int uio_major;
  45 static struct cdev *uio_cdev;
  46 static DEFINE_IDR(uio_idr);
  47 static const struct file_operations uio_fops;
  48
  49 /* Protect idr accesses */
  50 static DEFINE_MUTEX(minor_lock);
  51
  52 /*
  53  * attributes
  54  */
  55
  56 struct uio_map {
  57         struct kobject kobj;
  58         struct uio_mem *mem;
  59 };
  60 #define to_map(map) container_of(map, struct uio_map, kobj)
  61
  62 static ssize_t map_name_show(struct uio_mem *mem, char *buf)
  63 {
  64         if (unlikely(!mem->name))
  65                 mem->name = "";
  66
  67         return sprintf(buf, "%s\n", mem->name);
  68 }
  69
  70 static ssize_t map_addr_show(struct uio_mem *mem, char *buf)
  71 {
  72         return sprintf(buf, "0x%lx\n", mem->addr);
  73 }
  74
  75 static ssize_t map_size_show(struct uio_mem *mem, char *buf)
  76 {
  77         return sprintf(buf, "0x%lx\n", mem->size);
  78 }
  79
  80 static ssize_t map_offset_show(struct uio_mem *mem, char *buf)
  81 {
  82         return sprintf(buf, "0x%lx\n", mem->addr & ~PAGE_MASK);
  83 }
  84
  85 struct map_sysfs_entry {
  86         struct attribute attr;
  87         ssize_t (*show)(struct uio_mem *, char *);
  88         ssize_t (*store)(struct uio_mem *, const char *, size_t);
  89 };
  90
  91 static struct map_sysfs_entry name_attribute =
  92         __ATTR(name, S_IRUGO, map_name_show, NULL);
  93 static struct map_sysfs_entry addr_attribute =
  94         __ATTR(addr, S_IRUGO, map_addr_show, NULL);
  95 static struct map_sysfs_entry size_attribute =
  96         __ATTR(size, S_IRUGO, map_size_show, NULL);
  97 static struct map_sysfs_entry offset_attribute =
  98         __ATTR(offset, S_IRUGO, map_offset_show, NULL);
  99
 100 static struct attribute *attrs[] = {
 101         &name_attribute.attr,
 102         &addr_attribute.attr,
 103         &size_attribute.attr,
 104         &offset_attribute.attr,
 105         NULL,   /* need to NULL terminate the list of attributes */
 106 };
 107
 108 static void map_release(struct kobject *kobj)
 109 {
 110         struct uio_map *map = to_map(kobj);
 111         kfree(map);
 112 }
 113
 114 static ssize_t map_type_show(struct kobject *kobj, struct attribute *attr,
 115                              char *buf)
 116 {
 117         struct uio_map *map = to_map(kobj);
 118         struct uio_mem *mem = map->mem;
 119         struct map_sysfs_entry *entry;
 120
 121         entry = container_of(attr, struct map_sysfs_entry, attr);
 122
 123         if (!entry->show)
 124                 return -EIO;
 125
 126         return entry->show(mem, buf);
 127 }
 128
 129 static const struct sysfs_ops map_sysfs_ops = {
 130         .show = map_type_show,
 131 };
 132
 133 static struct kobj_type map_attr_type = {
 134         .release        = map_release,
 135         .sysfs_ops      = &map_sysfs_ops,
 136         .default_attrs  = attrs,
 137 };
 138
 139 struct uio_portio {
 140         struct kobject kobj;
 141         struct uio_port *port;
 142 };
 143 #define to_portio(portio) container_of(portio, struct uio_portio, kobj)
 144
 145 static ssize_t portio_name_show(struct uio_port *port, char *buf)
 146 {
 147         if (unlikely(!port->name))
 148                 port->name = "";
 149
 150         return sprintf(buf, "%s\n", port->name);
 151 }
 152
 153 static ssize_t portio_start_show(struct uio_port *port, char *buf)
 154 {
 155         return sprintf(buf, "0x%lx\n", port->start);
 156 }
 157
 158 static ssize_t portio_size_show(struct uio_port *port, char *buf)
 159 {
 160         return sprintf(buf, "0x%lx\n", port->size);
 161 }
 162
 163 static ssize_t portio_porttype_show(struct uio_port *port, char *buf)
 164 {
 165         const char *porttypes[] = {"none", "x86", "gpio", "other"};
 166
 167         if ((port->porttype < 0) || (port->porttype > UIO_PORT_OTHER))
 168                 return -EINVAL;
 169
 170         return sprintf(buf, "port_%s\n", porttypes[port->porttype]);
 171 }
 172
 173 struct portio_sysfs_entry {
 174         struct attribute attr;
 175         ssize_t (*show)(struct uio_port *, char *);
 176         ssize_t (*store)(struct uio_port *, const char *, size_t);
 177 };
 178
 179 static struct portio_sysfs_entry portio_name_attribute =
 180         __ATTR(name, S_IRUGO, portio_name_show, NULL);
 181 static struct portio_sysfs_entry portio_start_attribute =
 182         __ATTR(start, S_IRUGO, portio_start_show, NULL);
 183 static struct portio_sysfs_entry portio_size_attribute =
 184         __ATTR(size, S_IRUGO, portio_size_show, NULL);
 185 static struct portio_sysfs_entry portio_porttype_attribute =
 186         __ATTR(porttype, S_IRUGO, portio_porttype_show, NULL);
 187
 188 static struct attribute *portio_attrs[] = {
 189         &portio_name_attribute.attr,
 190         &portio_start_attribute.attr,
 191         &portio_size_attribute.attr,
 192         &portio_porttype_attribute.attr,
 193         NULL,
 194 };
 195
 196 static void portio_release(struct kobject *kobj)
 197 {
 198         struct uio_portio *portio = to_portio(kobj);
 199         kfree(portio);
 200 }
 201
 202 static ssize_t portio_type_show(struct kobject *kobj, struct attribute *attr,
 203                              char *buf)
 204 {
 205         struct uio_portio *portio = to_portio(kobj);
 206         struct uio_port *port = portio->port;
 207         struct portio_sysfs_entry *entry;
 208
 209         entry = container_of(attr, struct portio_sysfs_entry, attr);
 210
 211         if (!entry->show)
 212                 return -EIO;
 213
 214         return entry->show(port, buf);
 215 }
 216
 217 static const struct sysfs_ops portio_sysfs_ops = {
 218         .show = portio_type_show,
 219 };
 220
 221 static struct kobj_type portio_attr_type = {
 222         .release        = portio_release,
 223         .sysfs_ops      = &portio_sysfs_ops,
 224         .default_attrs  = portio_attrs,
 225 };
 226
 227 static ssize_t show_name(struct device *dev,
 228                          struct device_attribute *attr, char *buf)
 229 {
 230         struct uio_device *idev = dev_get_drvdata(dev);
 231         return sprintf(buf, "%s\n", idev->info->name);
 232 }
 233
 234 static ssize_t show_version(struct device *dev,
 235                             struct device_attribute *attr, char *buf)
 236 {
 237         struct uio_device *idev = dev_get_drvdata(dev);
 238         return sprintf(buf, "%s\n", idev->info->version);
 239 }
 240
 241 static ssize_t show_event(struct device *dev,
 242                           struct device_attribute *attr, char *buf)
 243 {
 244         struct uio_device *idev = dev_get_drvdata(dev);
 245         return sprintf(buf, "%u\n", (unsigned int)atomic_read(&idev->event));
 246 }
 247
 248 static struct device_attribute uio_class_attributes[] = {
 249         __ATTR(name, S_IRUGO, show_name, NULL),
 250         __ATTR(version, S_IRUGO, show_version, NULL),
 251         __ATTR(event, S_IRUGO, show_event, NULL),
 252         {}
 253 };
 254
 255 /* UIO class infrastructure */
 256 static struct class uio_class = {
 257         .name = "uio",
 258         .dev_attrs = uio_class_attributes,
 259 };
 260
 261 /*
 262  * device functions
 263  */
 264 static int uio_dev_add_attributes(struct uio_device *idev)
 265 {
 266         int ret;
 267         int mi, pi;
 268         int map_found = 0;
 269         int portio_found = 0;
 270         struct uio_mem *mem;
 271         struct uio_map *map;
 272         struct uio_port *port;
 273         struct uio_portio *portio;
 274
 275         for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
 276                 mem = &idev->info->mem[mi];
 277                 if (mem->size == 0)
 278                         break;
 279                 if (!map_found) {
 280                         map_found = 1;
 281                         idev->map_dir = kobject_create_and_add("maps",
 282                                                         &idev->dev->kobj);
 283                         if (!idev->map_dir)
 284                                 goto err_map;
 285                 }
 286                 map = kzalloc(sizeof(*map), GFP_KERNEL);
 287                 if (!map)
 288                         goto err_map;
 289                 kobject_init(&map->kobj, &map_attr_type);
 290                 map->mem = mem;
 291                 mem->map = map;
 292                 ret = kobject_add(&map->kobj, idev->map_dir, "map%d", mi);
 293                 if (ret)
 294                         goto err_map;
 295                 ret = kobject_uevent(&map->kobj, KOBJ_ADD);
 296                 if (ret)
 297                         goto err_map;
 298         }
 299
 300         for (pi = 0; pi < MAX_UIO_PORT_REGIONS; pi++) {
 301                 port = &idev->info->port[pi];
 302                 if (port->size == 0)
 303                         break;
 304                 if (!portio_found) {
 305                         portio_found = 1;
 306                         idev->portio_dir = kobject_create_and_add("portio",
 307                                                         &idev->dev->kobj);
 308                         if (!idev->portio_dir)
 309                                 goto err_portio;
 310                 }
 311                 portio = kzalloc(sizeof(*portio), GFP_KERNEL);
 312                 if (!portio)
 313                         goto err_portio;
 314                 kobject_init(&portio->kobj, &portio_attr_type);
 315                 portio->port = port;
 316                 port->portio = portio;
 317                 ret = kobject_add(&portio->kobj, idev->portio_dir,
 318                                                         "port%d", pi);
 319                 if (ret)
 320                         goto err_portio;
 321                 ret = kobject_uevent(&portio->kobj, KOBJ_ADD);
 322                 if (ret)
 323                         goto err_portio;
 324         }
 325
 326         return 0;
 327
 328 err_portio:
 329         for (pi--; pi >= 0; pi--) {
 330                 port = &idev->info->port[pi];
 331                 portio = port->portio;
 332                 kobject_put(&portio->kobj);
 333         }
 334         kobject_put(idev->portio_dir);
 335 err_map:
 336         for (mi--; mi>=0; mi--) {
 337                 mem = &idev->info->mem[mi];
 338                 map = mem->map;
 339                 kobject_put(&map->kobj);
 340         }
 341         kobject_put(idev->map_dir);
 342         dev_err(idev->dev, "error creating sysfs files (%d)\n", ret);
 343         return ret;
 344 }
 345
 346 static void uio_dev_del_attributes(struct uio_device *idev)
 347 {
 348         int i;
 349         struct uio_mem *mem;
 350         struct uio_port *port;
 351
 352         for (i = 0; i < MAX_UIO_MAPS; i++) {
 353                 mem = &idev->info->mem[i];
 354                 if (mem->size == 0)
 355                         break;
 356                 kobject_put(&mem->map->kobj);
 357         }
 358         kobject_put(idev->map_dir);
 359
 360         for (i = 0; i < MAX_UIO_PORT_REGIONS; i++) {
 361                 port = &idev->info->port[i];
 362                 if (port->size == 0)
 363                         break;
 364                 kobject_put(&port->portio->kobj);
 365         }
 366         kobject_put(idev->portio_dir);
 367 }
 368
 369 static int uio_get_minor(struct uio_device *idev)
 370 {
 371         int retval = -ENOMEM;
 372         int id;
 373
 374         mutex_lock(&minor_lock);
 375         if (idr_pre_get(&uio_idr, GFP_KERNEL) == 0)
 376                 goto exit;
 377
 378         retval = idr_get_new(&uio_idr, idev, &id);
 379         if (retval < 0) {
 380                 if (retval == -EAGAIN)
 381                         retval = -ENOMEM;
 382                 goto exit;
 383         }
 384         if (id < UIO_MAX_DEVICES) {
 385                 idev->minor = id;
 386         } else {
 387                 dev_err(idev->dev, "too many uio devices\n");
 388                 retval = -EINVAL;
 389                 idr_remove(&uio_idr, id);
 390         }
 391 exit:
 392         mutex_unlock(&minor_lock);
 393         return retval;
 394 }
 395
 396 static void uio_free_minor(struct uio_device *idev)
 397 {
 398         mutex_lock(&minor_lock);
 399         idr_remove(&uio_idr, idev->minor);
 400         mutex_unlock(&minor_lock);
 401 }
 402
 403 /**
 404  * uio_event_notify - trigger an interrupt event
 405  * @info: UIO device capabilities
 406  */
 407 void uio_event_notify(struct uio_info *info)
 408 {
 409         struct uio_device *idev = info->uio_dev;
 410
 411         atomic_inc(&idev->event);
 412         wake_up_interruptible(&idev->wait);
 413         kill_fasync(&idev->async_queue, SIGIO, POLL_IN);
 414 }
 415 EXPORT_SYMBOL_GPL(uio_event_notify);
 416
 417 /**
 418  * uio_interrupt - hardware interrupt handler
 419  * @irq: IRQ number, can be UIO_IRQ_CYCLIC for cyclic timer
 420  * @dev_id: Pointer to the devices uio_device structure
 421  */
 422 static irqreturn_t uio_interrupt(int irq, void *dev_id)
 423 {
 424         struct uio_device *idev = (struct uio_device *)dev_id;
 425         irqreturn_t ret = idev->info->handler(irq, idev->info);
 426
 427         if (ret == IRQ_HANDLED)
 428                 uio_event_notify(idev->info);
 429
 430         return ret;
 431 }
 432
 433 struct uio_listener {
 434         struct uio_device *dev;
 435         s32 event_count;
 436 };
 437
 438 static int uio_open(struct inode *inode, struct file *filep)
 439 {
 440         struct uio_device *idev;
 441         struct uio_listener *listener;
 442         int ret = 0;
 443
 444         mutex_lock(&minor_lock);
 445         idev = idr_find(&uio_idr, iminor(inode));
 446         mutex_unlock(&minor_lock);
 447         if (!idev) {
 448                 ret = -ENODEV;
 449                 goto out;
 450         }
 451
 452         if (!try_module_get(idev->owner)) {
 453                 ret = -ENODEV;
 454                 goto out;
 455         }
 456
 457         listener = kmalloc(sizeof(*listener), GFP_KERNEL);
 458         if (!listener) {
 459                 ret = -ENOMEM;
 460                 goto err_alloc_listener;
 461         }
 462
 463         listener->dev = idev;
 464         listener->event_count = atomic_read(&idev->event);
 465         filep->private_data = listener;
 466
 467         if (idev->info->open) {
 468                 ret = idev->info->open(idev->info, inode);
 469                 if (ret)
 470                         goto err_infoopen;
 471         }
 472         return 0;
 473
 474 err_infoopen:
 475         kfree(listener);
 476
 477 err_alloc_listener:
 478         module_put(idev->owner);
 479
 480 out:
 481         return ret;
 482 }
 483
 484 static int uio_fasync(int fd, struct file *filep, int on)
 485 {
 486         struct uio_listener *listener = filep->private_data;
 487         struct uio_device *idev = listener->dev;
 488
 489         return fasync_helper(fd, filep, on, &idev->async_queue);
 490 }
 491
 492 static int uio_release(struct inode *inode, struct file *filep)
 493 {
 494         int ret = 0;
 495         struct uio_listener *listener = filep->private_data;
 496         struct uio_device *idev = listener->dev;
 497
 498         if (idev->info->release)
 499                 ret = idev->info->release(idev->info, inode);
 500
 501         module_put(idev->owner);
 502         kfree(listener);
 503         return ret;
 504 }
 505
 506 static unsigned int uio_poll(struct file *filep, poll_table *wait)
 507 {
 508         struct uio_listener *listener = filep->private_data;
 509         struct uio_device *idev = listener->dev;
 510
 511         if (!idev->info->irq)
 512                 return -EIO;
 513
 514         poll_wait(filep, &idev->wait, wait);
 515         if (listener->event_count != atomic_read(&idev->event))
 516                 return POLLIN | POLLRDNORM;
 517         return 0;
 518 }
 519
 520 static ssize_t uio_read(struct file *filep, char __user *buf,
 521                         size_t count, loff_t *ppos)
 522 {
 523         struct uio_listener *listener = filep->private_data;
 524         struct uio_device *idev = listener->dev;
 525         DECLARE_WAITQUEUE(wait, current);
 526         ssize_t retval;
 527         s32 event_count;
 528
 529         if (!idev->info->irq)
 530                 return -EIO;
 531
 532         if (count != sizeof(s32))
 533                 return -EINVAL;
 534
 535         add_wait_queue(&idev->wait, &wait);
 536
 537         do {
 538                 set_current_state(TASK_INTERRUPTIBLE);
 539
 540                 event_count = atomic_read(&idev->event);
 541                 if (event_count != listener->event_count) {
 542                         if (copy_to_user(buf, &event_count, count))
 543                                 retval = -EFAULT;
 544                         else {
 545                                 listener->event_count = event_count;
 546                                 retval = count;
 547                         }
 548                         break;
 549                 }
 550
 551                 if (filep->f_flags & O_NONBLOCK) {
 552                         retval = -EAGAIN;
 553                         break;
 554                 }
 555
 556                 if (signal_pending(current)) {
 557                         retval = -ERESTARTSYS;
 558                         break;
 559                 }
 560                 schedule();
 561         } while (1);
 562
 563         __set_current_state(TASK_RUNNING);
 564         remove_wait_queue(&idev->wait, &wait);
 565
 566         return retval;
 567 }
 568
 569 static ssize_t uio_write(struct file *filep, const char __user *buf,
 570                         size_t count, loff_t *ppos)
 571 {
 572         struct uio_listener *listener = filep->private_data;
 573         struct uio_device *idev = listener->dev;
 574         ssize_t retval;
 575         s32 irq_on;
 576
 577         if (!idev->info->irq)
 578                 return -EIO;
 579
 580         if (count != sizeof(s32))
 581                 return -EINVAL;
 582
 583         if (!idev->info->irqcontrol)
 584                 return -ENOSYS;
 585
 586         if (copy_from_user(&irq_on, buf, count))
 587                 return -EFAULT;
 588
 589         retval = idev->info->irqcontrol(idev->info, irq_on);
 590
 591         return retval ? retval : sizeof(s32);
 592 }
 593
 594 static int uio_find_mem_index(struct vm_area_struct *vma)
 595 {
 596         struct uio_device *idev = vma->vm_private_data;
 597
 598         if (vma->vm_pgoff < MAX_UIO_MAPS) {
 599                 if (idev->info->mem[vma->vm_pgoff].size == 0)
 600                         return -1;
 601                 return (int)vma->vm_pgoff;
 602         }
 603         return -1;
 604 }
 605
 606 static void uio_vma_open(struct vm_area_struct *vma)
 607 {
 608         struct uio_device *idev = vma->vm_private_data;
 609         idev->vma_count++;
 610 }
 611
 612 static void uio_vma_close(struct vm_area_struct *vma)
 613 {
 614         struct uio_device *idev = vma->vm_private_data;
 615         idev->vma_count--;
 616 }
 617
 618 static int uio_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 619 {
 620         struct uio_device *idev = vma->vm_private_data;
 621         struct page *page;
 622         unsigned long offset;
 623
 624         int mi = uio_find_mem_index(vma);
 625         if (mi < 0)
 626                 return VM_FAULT_SIGBUS;
 627
 628         /*
 629          * We need to subtract mi because userspace uses offset = N*PAGE_SIZE
 630          * to use mem[N].
 631          */
 632         offset = (vmf->pgoff - mi) << PAGE_SHIFT;
 633
 634         if (idev->info->mem[mi].memtype == UIO_MEM_LOGICAL)
 635                 page = virt_to_page(idev->info->mem[mi].addr + offset);
 636         else
 637                 page = vmalloc_to_page((void *)idev->info->mem[mi].addr
 638                                                         + offset);
 639         get_page(page);
 640         vmf->page = page;
 641         return 0;
 642 }
 643
 644 static const struct vm_operations_struct uio_vm_ops = {
 645         .open = uio_vma_open,
 646         .close = uio_vma_close,
 647         .fault = uio_vma_fault,
 648 };
 649
 650 static int uio_mmap_physical(struct vm_area_struct *vma)
 651 {
 652         struct uio_device *idev = vma->vm_private_data;
 653         int mi = uio_find_mem_index(vma);
 654         if (mi < 0)
 655                 return -EINVAL;
 656
 657         vma->vm_flags |= VM_IO | VM_RESERVED;
 658
 659         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 660
 661         return remap_pfn_range(vma,
 662                                vma->vm_start,
 663                                idev->info->mem[mi].addr >> PAGE_SHIFT,
 664                                vma->vm_end - vma->vm_start,
 665                                vma->vm_page_prot);
 666 }
 667
 668 static int uio_mmap_logical(struct vm_area_struct *vma)
 669 {
 670         vma->vm_flags |= VM_RESERVED;
 671         vma->vm_ops = &uio_vm_ops;
 672         uio_vma_open(vma);
 673         return 0;
 674 }
 675
 676 static int uio_mmap(struct file *filep, struct vm_area_struct *vma)
 677 {
 678         struct uio_listener *listener = filep->private_data;
 679         struct uio_device *idev = listener->dev;
 680         int mi;
 681         unsigned long requested_pages, actual_pages;
 682         int ret = 0;
 683
 684         if (vma->vm_end < vma->vm_start)
 685                 return -EINVAL;
 686
 687         vma->vm_private_data = idev;
 688
 689         mi = uio_find_mem_index(vma);
 690         if (mi < 0)
 691                 return -EINVAL;
 692
 693         requested_pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 694         actual_pages = ((idev->info->mem[mi].addr & ~PAGE_MASK)
 695                         + idev->info->mem[mi].size + PAGE_SIZE -1) >> PAGE_SHIFT;
 696         if (requested_pages > actual_pages)
 697                 return -EINVAL;
 698
 699         if (idev->info->mmap) {
 700                 ret = idev->info->mmap(idev->info, vma);
 701                 return ret;
 702         }
 703
 704         switch (idev->info->mem[mi].memtype) {
 705                 case UIO_MEM_PHYS:
 706                         return uio_mmap_physical(vma);
 707                 case UIO_MEM_LOGICAL:
 708                 case UIO_MEM_VIRTUAL:
 709                         return uio_mmap_logical(vma);
 710                 default:
 711                         return -EINVAL;
 712         }
 713 }
 714
 715 static const struct file_operations uio_fops = {
 716         .owner          = THIS_MODULE,
 717         .open           = uio_open,
 718         .release        = uio_release,
 719         .read           = uio_read,
 720         .write          = uio_write,
 721         .mmap           = uio_mmap,
 722         .poll           = uio_poll,
 723         .fasync         = uio_fasync,
 724         .llseek         = noop_llseek,
 725 };
 726
 727 static int uio_major_init(void)
 728 {
 729         static const char name[] = "uio";
 730         struct cdev *cdev = NULL;
 731         dev_t uio_dev = 0;
 732         int result;
 733
 734         result = alloc_chrdev_region(&uio_dev, 0, UIO_MAX_DEVICES, name);
 735         if (result)
 736                 goto out;
 737
 738         result = -ENOMEM;
 739         cdev = cdev_alloc();
 740         if (!cdev)
 741                 goto out_unregister;
 742
 743         cdev->owner = THIS_MODULE;
 744         cdev->ops = &uio_fops;
 745         kobject_set_name(&cdev->kobj, "%s", name);
 746
 747         result = cdev_add(cdev, uio_dev, UIO_MAX_DEVICES);
 748         if (result)
 749                 goto out_put;
 750
 751         uio_major = MAJOR(uio_dev);
 752         uio_cdev = cdev;
 753         result = 0;
 754 out:
 755         return result;
 756 out_put:
 757         kobject_put(&cdev->kobj);
 758 out_unregister:
 759         unregister_chrdev_region(uio_dev, UIO_MAX_DEVICES);
 760         goto out;
 761 }
 762
 763 static void uio_major_cleanup(void)
 764 {
 765         unregister_chrdev_region(MKDEV(uio_major, 0), UIO_MAX_DEVICES);
 766         cdev_del(uio_cdev);
 767 }
 768
 769 static int init_uio_class(void)
 770 {
 771         int ret;
 772
 773         /* This is the first time in here, set everything up properly */
 774         ret = uio_major_init();
 775         if (ret)
 776                 goto exit;
 777
 778         ret = class_register(&uio_class);
 779         if (ret) {
 780                 printk(KERN_ERR "class_register failed for uio\n");
 781                 goto err_class_register;
 782         }
 783         return 0;
 784
 785 err_class_register:
 786         uio_major_cleanup();
 787 exit:
 788         return ret;
 789 }
 790
 791 static void release_uio_class(void)
 792 {
 793         class_unregister(&uio_class);
 794         uio_major_cleanup();
 795 }
 796
 797 /**
 798  * uio_register_device - register a new userspace IO device
 799  * @owner:      module that creates the new device
 800  * @parent:     parent device
 801  * @info:       UIO device capabilities
 802  *
 803  * returns zero on success or a negative error code.
 804  */
 805 int __uio_register_device(struct module *owner,
 806                           struct device *parent,
 807                           struct uio_info *info)
 808 {
 809         struct uio_device *idev;
 810         int ret = 0;
 811
 812         if (!parent || !info || !info->name || !info->version)
 813                 return -EINVAL;
 814
 815         info->uio_dev = NULL;
 816
 817         idev = kzalloc(sizeof(*idev), GFP_KERNEL);
 818         if (!idev) {
 819                 ret = -ENOMEM;
 820                 goto err_kzalloc;
 821         }
 822
 823         idev->owner = owner;
 824         idev->info = info;
 825         init_waitqueue_head(&idev->wait);
 826         atomic_set(&idev->event, 0);
 827
 828         ret = uio_get_minor(idev);
 829         if (ret)
 830                 goto err_get_minor;
 831
 832         idev->dev = device_create(&uio_class, parent,
 833                                   MKDEV(uio_major, idev->minor), idev,
 834                                   "uio%d", idev->minor);
 835         if (IS_ERR(idev->dev)) {
 836                 printk(KERN_ERR "UIO: device register failed\n");
 837                 ret = PTR_ERR(idev->dev);
 838                 goto err_device_create;
 839         }
 840
 841         ret = uio_dev_add_attributes(idev);
 842         if (ret)
 843                 goto err_uio_dev_add_attributes;
 844
 845         info->uio_dev = idev;
 846
 847         if (info->irq && (info->irq != UIO_IRQ_CUSTOM)) {
 848                 ret = request_irq(info->irq, uio_interrupt,
 849                                   info->irq_flags, info->name, idev);
 850                 if (ret)
 851                         goto err_request_irq;
 852         }
 853
 854         return 0;
 855
 856 err_request_irq:
 857         uio_dev_del_attributes(idev);
 858 err_uio_dev_add_attributes:
 859         device_destroy(&uio_class, MKDEV(uio_major, idev->minor));
 860 err_device_create:
 861         uio_free_minor(idev);
 862 err_get_minor:
 863         kfree(idev);
 864 err_kzalloc:
 865         return ret;
 866 }
 867 EXPORT_SYMBOL_GPL(__uio_register_device);
 868
 869 /**
 870  * uio_unregister_device - unregister a industrial IO device
 871  * @info:       UIO device capabilities
 872  *
 873  */
 874 void uio_unregister_device(struct uio_info *info)
 875 {
 876         struct uio_device *idev;
 877
 878         if (!info || !info->uio_dev)
 879                 return;
 880
 881         idev = info->uio_dev;
 882
 883         uio_free_minor(idev);
 884
 885         if (info->irq && (info->irq != UIO_IRQ_CUSTOM))
 886                 free_irq(info->irq, idev);
 887
 888         uio_dev_del_attributes(idev);
 889
 890         device_destroy(&uio_class, MKDEV(uio_major, idev->minor));
 891         kfree(idev);
 892
 893         return;
 894 }
 895 EXPORT_SYMBOL_GPL(uio_unregister_device);
 896
 897 static int __init uio_init(void)
 898 {
 899         return init_uio_class();
 900 }
 901
 902 static void __exit uio_exit(void)
 903 {
 904         release_uio_class();
 905 }
 906
 907 module_init(uio_init)
 908 module_exit(uio_exit)
 909 MODULE_LICENSE("GPL v2");