drivers/uio/uio.c

   1 /*
   2  * drivers/uio/uio.c
   3  *
   4  * Copyright(C) 2005, Benedikt Spranger <b.spranger@linutronix.de>
   5  * Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
   6  * Copyright(C) 2006, Hans J. Koch <hjk@linutronix.de>
   7  * Copyright(C) 2006, Greg Kroah-Hartman <greg@kroah.com>
   8  *
   9  * Userspace IO
  10  *
  11  * Base Functions
  12  *
  13  * Licensed under the GPLv2 only.
  14  */
  15
  16 #include <linux/module.h>
  17 #include <linux/init.h>
  18 #include <linux/poll.h>
  19 #include <linux/device.h>
  20 #include <linux/mm.h>
  21 #include <linux/idr.h>
  22 #include <linux/string.h>
  23 #include <linux/kobject.h>
  24 #include <linux/uio_driver.h>
  25
  26 #define UIO_MAX_DEVICES 255
  27
  28 struct uio_device {
  29         struct module           *owner;
  30         struct device           *dev;
  31         int                     minor;
  32         atomic_t                event;
  33         struct fasync_struct    *async_queue;
  34         wait_queue_head_t       wait;
  35         int                     vma_count;
  36         struct uio_info         *info;
  37         struct kobject          *map_dir;
  38 };
  39
  40 static int uio_major;
  41 static DEFINE_IDR(uio_idr);
  42 static const struct file_operations uio_fops;
  43
  44 /* UIO class infrastructure */
  45 static struct uio_class {
  46         struct kref kref;
  47         struct class *class;
  48 } *uio_class;
  49
  50 /*
  51  * attributes
  52  */
  53
  54 struct uio_map {
  55         struct kobject kobj;
  56         struct uio_mem *mem;
  57 };
  58 #define to_map(map) container_of(map, struct uio_map, kobj)
  59
  60 static ssize_t map_addr_show(struct uio_mem *mem, char *buf)
  61 {
  62         return sprintf(buf, "0x%lx\n", mem->addr);
  63 }
  64
  65 static ssize_t map_size_show(struct uio_mem *mem, char *buf)
  66 {
  67         return sprintf(buf, "0x%lx\n", mem->size);
  68 }
  69
  70 struct uio_sysfs_entry {
  71         struct attribute attr;
  72         ssize_t (*show)(struct uio_mem *, char *);
  73         ssize_t (*store)(struct uio_mem *, const char *, size_t);
  74 };
  75
  76 static struct uio_sysfs_entry addr_attribute =
  77         __ATTR(addr, S_IRUGO, map_addr_show, NULL);
  78 static struct uio_sysfs_entry size_attribute =
  79         __ATTR(size, S_IRUGO, map_size_show, NULL);
  80
  81 static struct attribute *attrs[] = {
  82         &addr_attribute.attr,
  83         &size_attribute.attr,
  84         NULL,   /* need to NULL terminate the list of attributes */
  85 };
  86
  87 static void map_release(struct kobject *kobj)
  88 {
  89         struct uio_map *map = to_map(kobj);
  90         kfree(map);
  91 }
  92
  93 static ssize_t map_type_show(struct kobject *kobj, struct attribute *attr,
  94                              char *buf)
  95 {
  96         struct uio_map *map = to_map(kobj);
  97         struct uio_mem *mem = map->mem;
  98         struct uio_sysfs_entry *entry;
  99
 100         entry = container_of(attr, struct uio_sysfs_entry, attr);
 101
 102         if (!entry->show)
 103                 return -EIO;
 104
 105         return entry->show(mem, buf);
 106 }
 107
 108 static struct sysfs_ops uio_sysfs_ops = {
 109         .show = map_type_show,
 110 };
 111
 112 static struct kobj_type map_attr_type = {
 113         .release        = map_release,
 114         .sysfs_ops      = &uio_sysfs_ops,
 115         .default_attrs  = attrs,
 116 };
 117
 118 static ssize_t show_name(struct device *dev,
 119                          struct device_attribute *attr, char *buf)
 120 {
 121         struct uio_device *idev = dev_get_drvdata(dev);
 122         if (idev)
 123                 return sprintf(buf, "%s\n", idev->info->name);
 124         else
 125                 return -ENODEV;
 126 }
 127 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
 128
 129 static ssize_t show_version(struct device *dev,
 130                             struct device_attribute *attr, char *buf)
 131 {
 132         struct uio_device *idev = dev_get_drvdata(dev);
 133         if (idev)
 134                 return sprintf(buf, "%s\n", idev->info->version);
 135         else
 136                 return -ENODEV;
 137 }
 138 static DEVICE_ATTR(version, S_IRUGO, show_version, NULL);
 139
 140 static ssize_t show_event(struct device *dev,
 141                           struct device_attribute *attr, char *buf)
 142 {
 143         struct uio_device *idev = dev_get_drvdata(dev);
 144         if (idev)
 145                 return sprintf(buf, "%u\n",
 146                                 (unsigned int)atomic_read(&idev->event));
 147         else
 148                 return -ENODEV;
 149 }
 150 static DEVICE_ATTR(event, S_IRUGO, show_event, NULL);
 151
 152 static struct attribute *uio_attrs[] = {
 153         &dev_attr_name.attr,
 154         &dev_attr_version.attr,
 155         &dev_attr_event.attr,
 156         NULL,
 157 };
 158
 159 static struct attribute_group uio_attr_grp = {
 160         .attrs = uio_attrs,
 161 };
 162
 163 /*
 164  * device functions
 165  */
 166 static int uio_dev_add_attributes(struct uio_device *idev)
 167 {
 168         int ret;
 169         int mi;
 170         int map_found = 0;
 171         struct uio_mem *mem;
 172         struct uio_map *map;
 173
 174         ret = sysfs_create_group(&idev->dev->kobj, &uio_attr_grp);
 175         if (ret)
 176                 goto err_group;
 177
 178         for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
 179                 mem = &idev->info->mem[mi];
 180                 if (mem->size == 0)
 181                         break;
 182                 if (!map_found) {
 183                         map_found = 1;
 184                         idev->map_dir = kobject_create_and_add("maps",
 185                                                         &idev->dev->kobj);
 186                         if (!idev->map_dir)
 187                                 goto err;
 188                 }
 189                 map = kzalloc(sizeof(*map), GFP_KERNEL);
 190                 if (!map)
 191                         goto err;
 192                 kobject_init(&map->kobj, &map_attr_type);
 193                 map->mem = mem;
 194                 mem->map = map;
 195                 ret = kobject_add(&map->kobj, idev->map_dir, "map%d", mi);
 196                 if (ret)
 197                         goto err;
 198                 ret = kobject_uevent(&map->kobj, KOBJ_ADD);
 199                 if (ret)
 200                         goto err;
 201         }
 202
 203         return 0;
 204
 205 err:
 206         for (mi--; mi>=0; mi--) {
 207                 mem = &idev->info->mem[mi];
 208                 map = mem->map;
 209                 kobject_put(&map->kobj);
 210         }
 211         kobject_put(idev->map_dir);
 212         sysfs_remove_group(&idev->dev->kobj, &uio_attr_grp);
 213 err_group:
 214         dev_err(idev->dev, "error creating sysfs files (%d)\n", ret);
 215         return ret;
 216 }
 217
 218 static void uio_dev_del_attributes(struct uio_device *idev)
 219 {
 220         int mi;
 221         struct uio_mem *mem;
 222         for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
 223                 mem = &idev->info->mem[mi];
 224                 if (mem->size == 0)
 225                         break;
 226                 kobject_put(&mem->map->kobj);
 227         }
 228         kobject_put(idev->map_dir);
 229         sysfs_remove_group(&idev->dev->kobj, &uio_attr_grp);
 230 }
 231
 232 static int uio_get_minor(struct uio_device *idev)
 233 {
 234         static DEFINE_MUTEX(minor_lock);
 235         int retval = -ENOMEM;
 236         int id;
 237
 238         mutex_lock(&minor_lock);
 239         if (idr_pre_get(&uio_idr, GFP_KERNEL) == 0)
 240                 goto exit;
 241
 242         retval = idr_get_new(&uio_idr, idev, &id);
 243         if (retval < 0) {
 244                 if (retval == -EAGAIN)
 245                         retval = -ENOMEM;
 246                 goto exit;
 247         }
 248         idev->minor = id & MAX_ID_MASK;
 249 exit:
 250         mutex_unlock(&minor_lock);
 251         return retval;
 252 }
 253
 254 static void uio_free_minor(struct uio_device *idev)
 255 {
 256         idr_remove(&uio_idr, idev->minor);
 257 }
 258
 259 /**
 260  * uio_event_notify - trigger an interrupt event
 261  * @info: UIO device capabilities
 262  */
 263 void uio_event_notify(struct uio_info *info)
 264 {
 265         struct uio_device *idev = info->uio_dev;
 266
 267         atomic_inc(&idev->event);
 268         wake_up_interruptible(&idev->wait);
 269         kill_fasync(&idev->async_queue, SIGIO, POLL_IN);
 270 }
 271 EXPORT_SYMBOL_GPL(uio_event_notify);
 272
 273 /**
 274  * uio_interrupt - hardware interrupt handler
 275  * @irq: IRQ number, can be UIO_IRQ_CYCLIC for cyclic timer
 276  * @dev_id: Pointer to the devices uio_device structure
 277  */
 278 static irqreturn_t uio_interrupt(int irq, void *dev_id)
 279 {
 280         struct uio_device *idev = (struct uio_device *)dev_id;
 281         irqreturn_t ret = idev->info->handler(irq, idev->info);
 282
 283         if (ret == IRQ_HANDLED)
 284                 uio_event_notify(idev->info);
 285
 286         return ret;
 287 }
 288
 289 struct uio_listener {
 290         struct uio_device *dev;
 291         s32 event_count;
 292 };
 293
 294 static int uio_open(struct inode *inode, struct file *filep)
 295 {
 296         struct uio_device *idev;
 297         struct uio_listener *listener;
 298         int ret = 0;
 299
 300         lock_kernel();
 301         idev = idr_find(&uio_idr, iminor(inode));
 302         if (!idev) {
 303                 ret = -ENODEV;
 304                 goto out;
 305         }
 306
 307         if (!try_module_get(idev->owner)) {
 308                 ret = -ENODEV;
 309                 goto out;
 310         }
 311
 312         listener = kmalloc(sizeof(*listener), GFP_KERNEL);
 313         if (!listener) {
 314                 ret = -ENOMEM;
 315                 goto err_alloc_listener;
 316         }
 317
 318         listener->dev = idev;
 319         listener->event_count = atomic_read(&idev->event);
 320         filep->private_data = listener;
 321
 322         if (idev->info->open) {
 323                 ret = idev->info->open(idev->info, inode);
 324                 if (ret)
 325                         goto err_infoopen;
 326         }
 327         unlock_kernel();
 328         return 0;
 329
 330 err_infoopen:
 331
 332         kfree(listener);
 333 err_alloc_listener:
 334
 335         module_put(idev->owner);
 336
 337 out:
 338         unlock_kernel();
 339         return ret;
 340 }
 341
 342 static int uio_fasync(int fd, struct file *filep, int on)
 343 {
 344         struct uio_listener *listener = filep->private_data;
 345         struct uio_device *idev = listener->dev;
 346
 347         return fasync_helper(fd, filep, on, &idev->async_queue);
 348 }
 349
 350 static int uio_release(struct inode *inode, struct file *filep)
 351 {
 352         int ret = 0;
 353         struct uio_listener *listener = filep->private_data;
 354         struct uio_device *idev = listener->dev;
 355
 356         if (idev->info->release)
 357                 ret = idev->info->release(idev->info, inode);
 358
 359         module_put(idev->owner);
 360
 361         if (filep->f_flags & FASYNC)
 362                 ret = uio_fasync(-1, filep, 0);
 363         kfree(listener);
 364         return ret;
 365 }
 366
 367 static unsigned int uio_poll(struct file *filep, poll_table *wait)
 368 {
 369         struct uio_listener *listener = filep->private_data;
 370         struct uio_device *idev = listener->dev;
 371
 372         if (idev->info->irq == UIO_IRQ_NONE)
 373                 return -EIO;
 374
 375         poll_wait(filep, &idev->wait, wait);
 376         if (listener->event_count != atomic_read(&idev->event))
 377                 return POLLIN | POLLRDNORM;
 378         return 0;
 379 }
 380
 381 static ssize_t uio_read(struct file *filep, char __user *buf,
 382                         size_t count, loff_t *ppos)
 383 {
 384         struct uio_listener *listener = filep->private_data;
 385         struct uio_device *idev = listener->dev;
 386         DECLARE_WAITQUEUE(wait, current);
 387         ssize_t retval;
 388         s32 event_count;
 389
 390         if (idev->info->irq == UIO_IRQ_NONE)
 391                 return -EIO;
 392
 393         if (count != sizeof(s32))
 394                 return -EINVAL;
 395
 396         add_wait_queue(&idev->wait, &wait);
 397
 398         do {
 399                 set_current_state(TASK_INTERRUPTIBLE);
 400
 401                 event_count = atomic_read(&idev->event);
 402                 if (event_count != listener->event_count) {
 403                         if (copy_to_user(buf, &event_count, count))
 404                                 retval = -EFAULT;
 405                         else {
 406                                 listener->event_count = event_count;
 407                                 retval = count;
 408                         }
 409                         break;
 410                 }
 411
 412                 if (filep->f_flags & O_NONBLOCK) {
 413                         retval = -EAGAIN;
 414                         break;
 415                 }
 416
 417                 if (signal_pending(current)) {
 418                         retval = -ERESTARTSYS;
 419                         break;
 420                 }
 421                 schedule();
 422         } while (1);
 423
 424         __set_current_state(TASK_RUNNING);
 425         remove_wait_queue(&idev->wait, &wait);
 426
 427         return retval;
 428 }
 429
 430 static int uio_find_mem_index(struct vm_area_struct *vma)
 431 {
 432         int mi;
 433         struct uio_device *idev = vma->vm_private_data;
 434
 435         for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
 436                 if (idev->info->mem[mi].size == 0)
 437                         return -1;
 438                 if (vma->vm_pgoff == mi)
 439                         return mi;
 440         }
 441         return -1;
 442 }
 443
 444 static void uio_vma_open(struct vm_area_struct *vma)
 445 {
 446         struct uio_device *idev = vma->vm_private_data;
 447         idev->vma_count++;
 448 }
 449
 450 static void uio_vma_close(struct vm_area_struct *vma)
 451 {
 452         struct uio_device *idev = vma->vm_private_data;
 453         idev->vma_count--;
 454 }
 455
 456 static int uio_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 457 {
 458         struct uio_device *idev = vma->vm_private_data;
 459         struct page *page;
 460
 461         int mi = uio_find_mem_index(vma);
 462         if (mi < 0)
 463                 return VM_FAULT_SIGBUS;
 464
 465         if (idev->info->mem[mi].memtype == UIO_MEM_LOGICAL)
 466                 page = virt_to_page(idev->info->mem[mi].addr);
 467         else
 468                 page = vmalloc_to_page((void*)idev->info->mem[mi].addr);
 469         get_page(page);
 470         vmf->page = page;
 471         return 0;
 472 }
 473
 474 static struct vm_operations_struct uio_vm_ops = {
 475         .open = uio_vma_open,
 476         .close = uio_vma_close,
 477         .fault = uio_vma_fault,
 478 };
 479
 480 static int uio_mmap_physical(struct vm_area_struct *vma)
 481 {
 482         struct uio_device *idev = vma->vm_private_data;
 483         int mi = uio_find_mem_index(vma);
 484         if (mi < 0)
 485                 return -EINVAL;
 486
 487         vma->vm_flags |= VM_IO | VM_RESERVED;
 488
 489         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 490
 491         return remap_pfn_range(vma,
 492                                vma->vm_start,
 493                                idev->info->mem[mi].addr >> PAGE_SHIFT,
 494                                vma->vm_end - vma->vm_start,
 495                                vma->vm_page_prot);
 496 }
 497
 498 static int uio_mmap_logical(struct vm_area_struct *vma)
 499 {
 500         vma->vm_flags |= VM_RESERVED;
 501         vma->vm_ops = &uio_vm_ops;
 502         uio_vma_open(vma);
 503         return 0;
 504 }
 505
 506 static int uio_mmap(struct file *filep, struct vm_area_struct *vma)
 507 {
 508         struct uio_listener *listener = filep->private_data;
 509         struct uio_device *idev = listener->dev;
 510         int mi;
 511         unsigned long requested_pages, actual_pages;
 512         int ret = 0;
 513
 514         if (vma->vm_end < vma->vm_start)
 515                 return -EINVAL;
 516
 517         vma->vm_private_data = idev;
 518
 519         mi = uio_find_mem_index(vma);
 520         if (mi < 0)
 521                 return -EINVAL;
 522
 523         requested_pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 524         actual_pages = (idev->info->mem[mi].size + PAGE_SIZE -1) >> PAGE_SHIFT;
 525         if (requested_pages > actual_pages)
 526                 return -EINVAL;
 527
 528         if (idev->info->mmap) {
 529                 ret = idev->info->mmap(idev->info, vma);
 530                 return ret;
 531         }
 532
 533         switch (idev->info->mem[mi].memtype) {
 534                 case UIO_MEM_PHYS:
 535                         return uio_mmap_physical(vma);
 536                 case UIO_MEM_LOGICAL:
 537                 case UIO_MEM_VIRTUAL:
 538                         return uio_mmap_logical(vma);
 539                 default:
 540                         return -EINVAL;
 541         }
 542 }
 543
 544 static const struct file_operations uio_fops = {
 545         .owner          = THIS_MODULE,
 546         .open           = uio_open,
 547         .release        = uio_release,
 548         .read           = uio_read,
 549         .mmap           = uio_mmap,
 550         .poll           = uio_poll,
 551         .fasync         = uio_fasync,
 552 };
 553
 554 static int uio_major_init(void)
 555 {
 556         uio_major = register_chrdev(0, "uio", &uio_fops);
 557         if (uio_major < 0)
 558                 return uio_major;
 559         return 0;
 560 }
 561
 562 static void uio_major_cleanup(void)
 563 {
 564         unregister_chrdev(uio_major, "uio");
 565 }
 566
 567 static int init_uio_class(void)
 568 {
 569         int ret = 0;
 570
 571         if (uio_class != NULL) {
 572                 kref_get(&uio_class->kref);
 573                 goto exit;
 574         }
 575
 576         /* This is the first time in here, set everything up properly */
 577         ret = uio_major_init();
 578         if (ret)
 579                 goto exit;
 580
 581         uio_class = kzalloc(sizeof(*uio_class), GFP_KERNEL);
 582         if (!uio_class) {
 583                 ret = -ENOMEM;
 584                 goto err_kzalloc;
 585         }
 586
 587         kref_init(&uio_class->kref);
 588         uio_class->class = class_create(THIS_MODULE, "uio");
 589         if (IS_ERR(uio_class->class)) {
 590                 ret = IS_ERR(uio_class->class);
 591                 printk(KERN_ERR "class_create failed for uio\n");
 592                 goto err_class_create;
 593         }
 594         return 0;
 595
 596 err_class_create:
 597         kfree(uio_class);
 598         uio_class = NULL;
 599 err_kzalloc:
 600         uio_major_cleanup();
 601 exit:
 602         return ret;
 603 }
 604
 605 static void release_uio_class(struct kref *kref)
 606 {
 607         /* Ok, we cheat as we know we only have one uio_class */
 608         class_destroy(uio_class->class);
 609         kfree(uio_class);
 610         uio_major_cleanup();
 611         uio_class = NULL;
 612 }
 613
 614 static void uio_class_destroy(void)
 615 {
 616         if (uio_class)
 617                 kref_put(&uio_class->kref, release_uio_class);
 618 }
 619
 620 /**
 621  * uio_register_device - register a new userspace IO device
 622  * @owner:      module that creates the new device
 623  * @parent:     parent device
 624  * @info:       UIO device capabilities
 625  *
 626  * returns zero on success or a negative error code.
 627  */
 628 int __uio_register_device(struct module *owner,
 629                           struct device *parent,
 630                           struct uio_info *info)
 631 {
 632         struct uio_device *idev;
 633         int ret = 0;
 634
 635         if (!parent || !info || !info->name || !info->version)
 636                 return -EINVAL;
 637
 638         info->uio_dev = NULL;
 639
 640         ret = init_uio_class();
 641         if (ret)
 642                 return ret;
 643
 644         idev = kzalloc(sizeof(*idev), GFP_KERNEL);
 645         if (!idev) {
 646                 ret = -ENOMEM;
 647                 goto err_kzalloc;
 648         }
 649
 650         idev->owner = owner;
 651         idev->info = info;
 652         init_waitqueue_head(&idev->wait);
 653         atomic_set(&idev->event, 0);
 654
 655         ret = uio_get_minor(idev);
 656         if (ret)
 657                 goto err_get_minor;
 658
 659         idev->dev = device_create_drvdata(uio_class->class, parent,
 660                                           MKDEV(uio_major, idev->minor), idev,
 661                                           "uio%d", idev->minor);
 662         if (IS_ERR(idev->dev)) {
 663                 printk(KERN_ERR "UIO: device register failed\n");
 664                 ret = PTR_ERR(idev->dev);
 665                 goto err_device_create;
 666         }
 667
 668         ret = uio_dev_add_attributes(idev);
 669         if (ret)
 670                 goto err_uio_dev_add_attributes;
 671
 672         info->uio_dev = idev;
 673
 674         if (idev->info->irq >= 0) {
 675                 ret = request_irq(idev->info->irq, uio_interrupt,
 676                                   idev->info->irq_flags, idev->info->name, idev);
 677                 if (ret)
 678                         goto err_request_irq;
 679         }
 680
 681         return 0;
 682
 683 err_request_irq:
 684         uio_dev_del_attributes(idev);
 685 err_uio_dev_add_attributes:
 686         device_destroy(uio_class->class, MKDEV(uio_major, idev->minor));
 687 err_device_create:
 688         uio_free_minor(idev);
 689 err_get_minor:
 690         kfree(idev);
 691 err_kzalloc:
 692         uio_class_destroy();
 693         return ret;
 694 }
 695 EXPORT_SYMBOL_GPL(__uio_register_device);
 696
 697 /**
 698  * uio_unregister_device - unregister a industrial IO device
 699  * @info:       UIO device capabilities
 700  *
 701  */
 702 void uio_unregister_device(struct uio_info *info)
 703 {
 704         struct uio_device *idev;
 705
 706         if (!info || !info->uio_dev)
 707                 return;
 708
 709         idev = info->uio_dev;
 710
 711         uio_free_minor(idev);
 712
 713         if (info->irq >= 0)
 714                 free_irq(info->irq, idev);
 715
 716         uio_dev_del_attributes(idev);
 717
 718         dev_set_drvdata(idev->dev, NULL);
 719         device_destroy(uio_class->class, MKDEV(uio_major, idev->minor));
 720         kfree(idev);
 721         uio_class_destroy();
 722
 723         return;
 724 }
 725 EXPORT_SYMBOL_GPL(uio_unregister_device);
 726
 727 static int __init uio_init(void)
 728 {
 729         return 0;
 730 }
 731
 732 static void __exit uio_exit(void)
 733 {
 734 }
 735
 736 module_init(uio_init)
 737 module_exit(uio_exit)
 738 MODULE_LICENSE("GPL v2");