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