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         struct uio_info         *info;
  39         struct kobject          *map_dir;
  40         struct kobject          *portio_dir;
  41 };
  42
  43 static int uio_major;
  44 static struct cdev *uio_cdev;
  45 static DEFINE_IDR(uio_idr);
  46 static const struct file_operations uio_fops;
  47
  48 /* Protect idr accesses */
  49 static DEFINE_MUTEX(minor_lock);
  50
  51 /*
  52  * attributes
  53  */
  54
  55 struct uio_map {
  56         struct kobject kobj;
  57         struct uio_mem *mem;
  58 };
  59 #define to_map(map) container_of(map, struct uio_map, kobj)
  60
  61 static ssize_t map_name_show(struct uio_mem *mem, char *buf)
  62 {
  63         if (unlikely(!mem->name))
  64                 mem->name = "";
  65
  66         return sprintf(buf, "%s\n", mem->name);
  67 }
  68
  69 static ssize_t map_addr_show(struct uio_mem *mem, char *buf)
  70 {
  71         return sprintf(buf, "0x%llx\n", (unsigned long long)mem->addr);
  72 }
  73
  74 static ssize_t map_size_show(struct uio_mem *mem, char *buf)
  75 {
  76         return sprintf(buf, "0x%lx\n", mem->size);
  77 }
  78
  79 static ssize_t map_offset_show(struct uio_mem *mem, char *buf)
  80 {
  81         return sprintf(buf, "0x%llx\n", (unsigned long long)mem->addr & ~PAGE_MASK);
  82 }
  83
  84 struct map_sysfs_entry {
  85         struct attribute attr;
  86         ssize_t (*show)(struct uio_mem *, char *);
  87         ssize_t (*store)(struct uio_mem *, const char *, size_t);
  88 };
  89
  90 static struct map_sysfs_entry name_attribute =
  91         __ATTR(name, S_IRUGO, map_name_show, NULL);
  92 static struct map_sysfs_entry addr_attribute =
  93         __ATTR(addr, S_IRUGO, map_addr_show, NULL);
  94 static struct map_sysfs_entry size_attribute =
  95         __ATTR(size, S_IRUGO, map_size_show, NULL);
  96 static struct map_sysfs_entry offset_attribute =
  97         __ATTR(offset, S_IRUGO, map_offset_show, NULL);
  98
  99 static struct attribute *attrs[] = {
 100         &name_attribute.attr,
 101         &addr_attribute.attr,
 102         &size_attribute.attr,
 103         &offset_attribute.attr,
 104         NULL,   /* need to NULL terminate the list of attributes */
 105 };
 106
 107 static void map_release(struct kobject *kobj)
 108 {
 109         struct uio_map *map = to_map(kobj);
 110         kfree(map);
 111 }
 112
 113 static ssize_t map_type_show(struct kobject *kobj, struct attribute *attr,
 114                              char *buf)
 115 {
 116         struct uio_map *map = to_map(kobj);
 117         struct uio_mem *mem = map->mem;
 118         struct map_sysfs_entry *entry;
 119
 120         entry = container_of(attr, struct map_sysfs_entry, attr);
 121
 122         if (!entry->show)
 123                 return -EIO;
 124
 125         return entry->show(mem, buf);
 126 }
 127
 128 static const struct sysfs_ops map_sysfs_ops = {
 129         .show = map_type_show,
 130 };
 131
 132 static struct kobj_type map_attr_type = {
 133         .release        = map_release,
 134         .sysfs_ops      = &map_sysfs_ops,
 135         .default_attrs  = attrs,
 136 };
 137
 138 struct uio_portio {
 139         struct kobject kobj;
 140         struct uio_port *port;
 141 };
 142 #define to_portio(portio) container_of(portio, struct uio_portio, kobj)
 143
 144 static ssize_t portio_name_show(struct uio_port *port, char *buf)
 145 {
 146         if (unlikely(!port->name))
 147                 port->name = "";
 148
 149         return sprintf(buf, "%s\n", port->name);
 150 }
 151
 152 static ssize_t portio_start_show(struct uio_port *port, char *buf)
 153 {
 154         return sprintf(buf, "0x%lx\n", port->start);
 155 }
 156
 157 static ssize_t portio_size_show(struct uio_port *port, char *buf)
 158 {
 159         return sprintf(buf, "0x%lx\n", port->size);
 160 }
 161
 162 static ssize_t portio_porttype_show(struct uio_port *port, char *buf)
 163 {
 164         const char *porttypes[] = {"none", "x86", "gpio", "other"};
 165
 166         if ((port->porttype < 0) || (port->porttype > UIO_PORT_OTHER))
 167                 return -EINVAL;
 168
 169         return sprintf(buf, "port_%s\n", porttypes[port->porttype]);
 170 }
 171
 172 struct portio_sysfs_entry {
 173         struct attribute attr;
 174         ssize_t (*show)(struct uio_port *, char *);
 175         ssize_t (*store)(struct uio_port *, const char *, size_t);
 176 };
 177
 178 static struct portio_sysfs_entry portio_name_attribute =
 179         __ATTR(name, S_IRUGO, portio_name_show, NULL);
 180 static struct portio_sysfs_entry portio_start_attribute =
 181         __ATTR(start, S_IRUGO, portio_start_show, NULL);
 182 static struct portio_sysfs_entry portio_size_attribute =
 183         __ATTR(size, S_IRUGO, portio_size_show, NULL);
 184 static struct portio_sysfs_entry portio_porttype_attribute =
 185         __ATTR(porttype, S_IRUGO, portio_porttype_show, NULL);
 186
 187 static struct attribute *portio_attrs[] = {
 188         &portio_name_attribute.attr,
 189         &portio_start_attribute.attr,
 190         &portio_size_attribute.attr,
 191         &portio_porttype_attribute.attr,
 192         NULL,
 193 };
 194
 195 static void portio_release(struct kobject *kobj)
 196 {
 197         struct uio_portio *portio = to_portio(kobj);
 198         kfree(portio);
 199 }
 200
 201 static ssize_t portio_type_show(struct kobject *kobj, struct attribute *attr,
 202                              char *buf)
 203 {
 204         struct uio_portio *portio = to_portio(kobj);
 205         struct uio_port *port = portio->port;
 206         struct portio_sysfs_entry *entry;
 207
 208         entry = container_of(attr, struct portio_sysfs_entry, attr);
 209
 210         if (!entry->show)
 211                 return -EIO;
 212
 213         return entry->show(port, buf);
 214 }
 215
 216 static const struct sysfs_ops portio_sysfs_ops = {
 217         .show = portio_type_show,
 218 };
 219
 220 static struct kobj_type portio_attr_type = {
 221         .release        = portio_release,
 222         .sysfs_ops      = &portio_sysfs_ops,
 223         .default_attrs  = portio_attrs,
 224 };
 225
 226 static ssize_t name_show(struct device *dev,
 227                          struct device_attribute *attr, char *buf)
 228 {
 229         struct uio_device *idev = dev_get_drvdata(dev);
 230         return sprintf(buf, "%s\n", idev->info->name);
 231 }
 232 static DEVICE_ATTR_RO(name);
 233
 234 static ssize_t version_show(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 static DEVICE_ATTR_RO(version);
 241
 242 static ssize_t event_show(struct device *dev,
 243                           struct device_attribute *attr, char *buf)
 244 {
 245         struct uio_device *idev = dev_get_drvdata(dev);
 246         return sprintf(buf, "%u\n", (unsigned int)atomic_read(&idev->event));
 247 }
 248 static DEVICE_ATTR_RO(event);
 249
 250 static struct attribute *uio_attrs[] = {
 251         &dev_attr_name.attr,
 252         &dev_attr_version.attr,
 253         &dev_attr_event.attr,
 254         NULL,
 255 };
 256 ATTRIBUTE_GROUPS(uio);
 257
 258 /* UIO class infrastructure */
 259 static struct class uio_class = {
 260         .name = "uio",
 261         .dev_groups = uio_groups,
 262 };
 263
 264 /*
 265  * device functions
 266  */
 267 static int uio_dev_add_attributes(struct uio_device *idev)
 268 {
 269         int ret;
 270         int mi, pi;
 271         int map_found = 0;
 272         int portio_found = 0;
 273         struct uio_mem *mem;
 274         struct uio_map *map;
 275         struct uio_port *port;
 276         struct uio_portio *portio;
 277
 278         for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
 279                 mem = &idev->info->mem[mi];
 280                 if (mem->size == 0)
 281                         break;
 282                 if (!map_found) {
 283                         map_found = 1;
 284                         idev->map_dir = kobject_create_and_add("maps",
 285                                                         &idev->dev->kobj);
 286                         if (!idev->map_dir)
 287                                 goto err_map;
 288                 }
 289                 map = kzalloc(sizeof(*map), GFP_KERNEL);
 290                 if (!map)
 291                         goto err_map;
 292                 kobject_init(&map->kobj, &map_attr_type);
 293                 map->mem = mem;
 294                 mem->map = map;
 295                 ret = kobject_add(&map->kobj, idev->map_dir, "map%d", mi);
 296                 if (ret)
 297                         goto err_map;
 298                 ret = kobject_uevent(&map->kobj, KOBJ_ADD);
 299                 if (ret)
 300                         goto err_map;
 301         }
 302
 303         for (pi = 0; pi < MAX_UIO_PORT_REGIONS; pi++) {
 304                 port = &idev->info->port[pi];
 305                 if (port->size == 0)
 306                         break;
 307                 if (!portio_found) {
 308                         portio_found = 1;
 309                         idev->portio_dir = kobject_create_and_add("portio",
 310                                                         &idev->dev->kobj);
 311                         if (!idev->portio_dir)
 312                                 goto err_portio;
 313                 }
 314                 portio = kzalloc(sizeof(*portio), GFP_KERNEL);
 315                 if (!portio)
 316                         goto err_portio;
 317                 kobject_init(&portio->kobj, &portio_attr_type);
 318                 portio->port = port;
 319                 port->portio = portio;
 320                 ret = kobject_add(&portio->kobj, idev->portio_dir,
 321                                                         "port%d", pi);
 322                 if (ret)
 323                         goto err_portio;
 324                 ret = kobject_uevent(&portio->kobj, KOBJ_ADD);
 325                 if (ret)
 326                         goto err_portio;
 327         }
 328
 329         return 0;
 330
 331 err_portio:
 332         for (pi--; pi >= 0; pi--) {
 333                 port = &idev->info->port[pi];
 334                 portio = port->portio;
 335                 kobject_put(&portio->kobj);
 336         }
 337         kobject_put(idev->portio_dir);
 338 err_map:
 339         for (mi--; mi>=0; mi--) {
 340                 mem = &idev->info->mem[mi];
 341                 map = mem->map;
 342                 kobject_put(&map->kobj);
 343         }
 344         kobject_put(idev->map_dir);
 345         dev_err(idev->dev, "error creating sysfs files (%d)\n", ret);
 346         return ret;
 347 }
 348
 349 static void uio_dev_del_attributes(struct uio_device *idev)
 350 {
 351         int i;
 352         struct uio_mem *mem;
 353         struct uio_port *port;
 354
 355         for (i = 0; i < MAX_UIO_MAPS; i++) {
 356                 mem = &idev->info->mem[i];
 357                 if (mem->size == 0)
 358                         break;
 359                 kobject_put(&mem->map->kobj);
 360         }
 361         kobject_put(idev->map_dir);
 362
 363         for (i = 0; i < MAX_UIO_PORT_REGIONS; i++) {
 364                 port = &idev->info->port[i];
 365                 if (port->size == 0)
 366                         break;
 367                 kobject_put(&port->portio->kobj);
 368         }
 369         kobject_put(idev->portio_dir);
 370 }
 371
 372 static int uio_get_minor(struct uio_device *idev)
 373 {
 374         int retval = -ENOMEM;
 375
 376         mutex_lock(&minor_lock);
 377         retval = idr_alloc(&uio_idr, idev, 0, UIO_MAX_DEVICES, GFP_KERNEL);
 378         if (retval >= 0) {
 379                 idev->minor = retval;
 380                 retval = 0;
 381         } else if (retval == -ENOSPC) {
 382                 dev_err(idev->dev, "too many uio devices\n");
 383                 retval = -EINVAL;
 384         }
 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)
 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)
 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)
 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         struct uio_device *idev = vma->vm_private_data;
 590
 591         if (vma->vm_pgoff < MAX_UIO_MAPS) {
 592                 if (idev->info->mem[vma->vm_pgoff].size == 0)
 593                         return -1;
 594                 return (int)vma->vm_pgoff;
 595         }
 596         return -1;
 597 }
 598
 599 static int uio_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 600 {
 601         struct uio_device *idev = vma->vm_private_data;
 602         struct page *page;
 603         unsigned long offset;
 604
 605         int mi = uio_find_mem_index(vma);
 606         if (mi < 0)
 607                 return VM_FAULT_SIGBUS;
 608
 609         /*
 610          * We need to subtract mi because userspace uses offset = N*PAGE_SIZE
 611          * to use mem[N].
 612          */
 613         offset = (vmf->pgoff - mi) << PAGE_SHIFT;
 614
 615         if (idev->info->mem[mi].memtype == UIO_MEM_LOGICAL)
 616                 page = virt_to_page(idev->info->mem[mi].addr + offset);
 617         else
 618                 page = vmalloc_to_page((void *)(unsigned long)idev->info->mem[mi].addr + offset);
 619         get_page(page);
 620         vmf->page = page;
 621         return 0;
 622 }
 623
 624 static const struct vm_operations_struct uio_logical_vm_ops = {
 625         .fault = uio_vma_fault,
 626 };
 627
 628 static int uio_mmap_logical(struct vm_area_struct *vma)
 629 {
 630         vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
 631         vma->vm_ops = &uio_logical_vm_ops;
 632         return 0;
 633 }
 634
 635 static const struct vm_operations_struct uio_physical_vm_ops = {
 636 #ifdef CONFIG_HAVE_IOREMAP_PROT
 637         .access = generic_access_phys,
 638 #endif
 639 };
 640
 641 static int uio_mmap_physical(struct vm_area_struct *vma)
 642 {
 643         struct uio_device *idev = vma->vm_private_data;
 644         int mi = uio_find_mem_index(vma);
 645         struct uio_mem *mem;
 646         if (mi < 0)
 647                 return -EINVAL;
 648         mem = idev->info->mem + mi;
 649
 650         if (vma->vm_end - vma->vm_start > mem->size)
 651                 return -EINVAL;
 652
 653         vma->vm_ops = &uio_physical_vm_ops;
 654         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 655
 656         /*
 657          * We cannot use the vm_iomap_memory() helper here,
 658          * because vma->vm_pgoff is the map index we looked
 659          * up above in uio_find_mem_index(), rather than an
 660          * actual page offset into the mmap.
 661          *
 662          * So we just do the physical mmap without a page
 663          * offset.
 664          */
 665         return remap_pfn_range(vma,
 666                                vma->vm_start,
 667                                mem->addr >> PAGE_SHIFT,
 668                                vma->vm_end - vma->vm_start,
 669                                vma->vm_page_prot);
 670 }
 671
 672 static int uio_mmap(struct file *filep, struct vm_area_struct *vma)
 673 {
 674         struct uio_listener *listener = filep->private_data;
 675         struct uio_device *idev = listener->dev;
 676         int mi;
 677         unsigned long requested_pages, actual_pages;
 678         int ret = 0;
 679
 680         if (vma->vm_end < vma->vm_start)
 681                 return -EINVAL;
 682
 683         vma->vm_private_data = idev;
 684
 685         mi = uio_find_mem_index(vma);
 686         if (mi < 0)
 687                 return -EINVAL;
 688
 689         requested_pages = vma_pages(vma);
 690         actual_pages = ((idev->info->mem[mi].addr & ~PAGE_MASK)
 691                         + idev->info->mem[mi].size + PAGE_SIZE -1) >> PAGE_SHIFT;
 692         if (requested_pages > actual_pages)
 693                 return -EINVAL;
 694
 695         if (idev->info->mmap) {
 696                 ret = idev->info->mmap(idev->info, vma);
 697                 return ret;
 698         }
 699
 700         switch (idev->info->mem[mi].memtype) {
 701                 case UIO_MEM_PHYS:
 702                         return uio_mmap_physical(vma);
 703                 case UIO_MEM_LOGICAL:
 704                 case UIO_MEM_VIRTUAL:
 705                         return uio_mmap_logical(vma);
 706                 default:
 707                         return -EINVAL;
 708         }
 709 }
 710
 711 static const struct file_operations uio_fops = {
 712         .owner          = THIS_MODULE,
 713         .open           = uio_open,
 714         .release        = uio_release,
 715         .read           = uio_read,
 716         .write          = uio_write,
 717         .mmap           = uio_mmap,
 718         .poll           = uio_poll,
 719         .fasync         = uio_fasync,
 720         .llseek         = noop_llseek,
 721 };
 722
 723 static int uio_major_init(void)
 724 {
 725         static const char name[] = "uio";
 726         struct cdev *cdev = NULL;
 727         dev_t uio_dev = 0;
 728         int result;
 729
 730         result = alloc_chrdev_region(&uio_dev, 0, UIO_MAX_DEVICES, name);
 731         if (result)
 732                 goto out;
 733
 734         result = -ENOMEM;
 735         cdev = cdev_alloc();
 736         if (!cdev)
 737                 goto out_unregister;
 738
 739         cdev->owner = THIS_MODULE;
 740         cdev->ops = &uio_fops;
 741         kobject_set_name(&cdev->kobj, "%s", name);
 742
 743         result = cdev_add(cdev, uio_dev, UIO_MAX_DEVICES);
 744         if (result)
 745                 goto out_put;
 746
 747         uio_major = MAJOR(uio_dev);
 748         uio_cdev = cdev;
 749         return 0;
 750 out_put:
 751         kobject_put(&cdev->kobj);
 752 out_unregister:
 753         unregister_chrdev_region(uio_dev, UIO_MAX_DEVICES);
 754 out:
 755         return result;
 756 }
 757
 758 static void uio_major_cleanup(void)
 759 {
 760         unregister_chrdev_region(MKDEV(uio_major, 0), UIO_MAX_DEVICES);
 761         cdev_del(uio_cdev);
 762 }
 763
 764 static int init_uio_class(void)
 765 {
 766         int ret;
 767
 768         /* This is the first time in here, set everything up properly */
 769         ret = uio_major_init();
 770         if (ret)
 771                 goto exit;
 772
 773         ret = class_register(&uio_class);
 774         if (ret) {
 775                 printk(KERN_ERR "class_register failed for uio\n");
 776                 goto err_class_register;
 777         }
 778         return 0;
 779
 780 err_class_register:
 781         uio_major_cleanup();
 782 exit:
 783         return ret;
 784 }
 785
 786 static void release_uio_class(void)
 787 {
 788         class_unregister(&uio_class);
 789         uio_major_cleanup();
 790 }
 791
 792 /**
 793  * uio_register_device - register a new userspace IO device
 794  * @owner:      module that creates the new device
 795  * @parent:     parent device
 796  * @info:       UIO device capabilities
 797  *
 798  * returns zero on success or a negative error code.
 799  */
 800 int __uio_register_device(struct module *owner,
 801                           struct device *parent,
 802                           struct uio_info *info)
 803 {
 804         struct uio_device *idev;
 805         int ret = 0;
 806
 807         if (!parent || !info || !info->name || !info->version)
 808                 return -EINVAL;
 809
 810         info->uio_dev = NULL;
 811
 812         idev = kzalloc(sizeof(*idev), GFP_KERNEL);
 813         if (!idev) {
 814                 ret = -ENOMEM;
 815                 goto err_kzalloc;
 816         }
 817
 818         idev->owner = owner;
 819         idev->info = info;
 820         init_waitqueue_head(&idev->wait);
 821         atomic_set(&idev->event, 0);
 822
 823         ret = uio_get_minor(idev);
 824         if (ret)
 825                 goto err_get_minor;
 826
 827         idev->dev = device_create(&uio_class, parent,
 828                                   MKDEV(uio_major, idev->minor), idev,
 829                                   "uio%d", idev->minor);
 830         if (IS_ERR(idev->dev)) {
 831                 printk(KERN_ERR "UIO: device register failed\n");
 832                 ret = PTR_ERR(idev->dev);
 833                 goto err_device_create;
 834         }
 835
 836         ret = uio_dev_add_attributes(idev);
 837         if (ret)
 838                 goto err_uio_dev_add_attributes;
 839
 840         info->uio_dev = idev;
 841
 842         if (info->irq && (info->irq != UIO_IRQ_CUSTOM)) {
 843                 ret = request_irq(info->irq, uio_interrupt,
 844                                   info->irq_flags, info->name, idev);
 845                 if (ret)
 846                         goto err_request_irq;
 847         }
 848
 849         return 0;
 850
 851 err_request_irq:
 852         uio_dev_del_attributes(idev);
 853 err_uio_dev_add_attributes:
 854         device_destroy(&uio_class, MKDEV(uio_major, idev->minor));
 855 err_device_create:
 856         uio_free_minor(idev);
 857 err_get_minor:
 858         kfree(idev);
 859 err_kzalloc:
 860         return ret;
 861 }
 862 EXPORT_SYMBOL_GPL(__uio_register_device);
 863
 864 /**
 865  * uio_unregister_device - unregister a industrial IO device
 866  * @info:       UIO device capabilities
 867  *
 868  */
 869 void uio_unregister_device(struct uio_info *info)
 870 {
 871         struct uio_device *idev;
 872
 873         if (!info || !info->uio_dev)
 874                 return;
 875
 876         idev = info->uio_dev;
 877
 878         uio_free_minor(idev);
 879
 880         if (info->irq && (info->irq != UIO_IRQ_CUSTOM))
 881                 free_irq(info->irq, idev);
 882
 883         uio_dev_del_attributes(idev);
 884
 885         device_destroy(&uio_class, MKDEV(uio_major, idev->minor));
 886         kfree(idev);
 887
 888         return;
 889 }
 890 EXPORT_SYMBOL_GPL(uio_unregister_device);
 891
 892 static int __init uio_init(void)
 893 {
 894         return init_uio_class();
 895 }
 896
 897 static void __exit uio_exit(void)
 898 {
 899         release_uio_class();
 900 }
 901
 902 module_init(uio_init)
 903 module_exit(uio_exit)
 904 MODULE_LICENSE("GPL v2");