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