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         idev = idr_find(&uio_idr, iminor(inode));
 301         if (!idev)
 302                 return -ENODEV;
 303
 304         listener = kmalloc(sizeof(*listener), GFP_KERNEL);
 305         if (!listener)
 306                 return -ENOMEM;
 307
 308         listener->dev = idev;
 309         listener->event_count = atomic_read(&idev->event);
 310         filep->private_data = listener;
 311
 312         if (idev->info->open) {
 313                 if (!try_module_get(idev->owner))
 314                         return -ENODEV;
 315                 ret = idev->info->open(idev->info, inode);
 316                 module_put(idev->owner);
 317         }
 318
 319         if (ret)
 320                 kfree(listener);
 321
 322         return ret;
 323 }
 324
 325 static int uio_fasync(int fd, struct file *filep, int on)
 326 {
 327         struct uio_listener *listener = filep->private_data;
 328         struct uio_device *idev = listener->dev;
 329
 330         return fasync_helper(fd, filep, on, &idev->async_queue);
 331 }
 332
 333 static int uio_release(struct inode *inode, struct file *filep)
 334 {
 335         int ret = 0;
 336         struct uio_listener *listener = filep->private_data;
 337         struct uio_device *idev = listener->dev;
 338
 339         if (idev->info->release) {
 340                 if (!try_module_get(idev->owner))
 341                         return -ENODEV;
 342                 ret = idev->info->release(idev->info, inode);
 343                 module_put(idev->owner);
 344         }
 345         if (filep->f_flags & FASYNC)
 346                 ret = uio_fasync(-1, filep, 0);
 347         kfree(listener);
 348         return ret;
 349 }
 350
 351 static unsigned int uio_poll(struct file *filep, poll_table *wait)
 352 {
 353         struct uio_listener *listener = filep->private_data;
 354         struct uio_device *idev = listener->dev;
 355
 356         if (idev->info->irq == UIO_IRQ_NONE)
 357                 return -EIO;
 358
 359         poll_wait(filep, &idev->wait, wait);
 360         if (listener->event_count != atomic_read(&idev->event))
 361                 return POLLIN | POLLRDNORM;
 362         return 0;
 363 }
 364
 365 static ssize_t uio_read(struct file *filep, char __user *buf,
 366                         size_t count, loff_t *ppos)
 367 {
 368         struct uio_listener *listener = filep->private_data;
 369         struct uio_device *idev = listener->dev;
 370         DECLARE_WAITQUEUE(wait, current);
 371         ssize_t retval;
 372         s32 event_count;
 373
 374         if (idev->info->irq == UIO_IRQ_NONE)
 375                 return -EIO;
 376
 377         if (count != sizeof(s32))
 378                 return -EINVAL;
 379
 380         add_wait_queue(&idev->wait, &wait);
 381
 382         do {
 383                 set_current_state(TASK_INTERRUPTIBLE);
 384
 385                 event_count = atomic_read(&idev->event);
 386                 if (event_count != listener->event_count) {
 387                         if (copy_to_user(buf, &event_count, count))
 388                                 retval = -EFAULT;
 389                         else {
 390                                 listener->event_count = event_count;
 391                                 retval = count;
 392                         }
 393                         break;
 394                 }
 395
 396                 if (filep->f_flags & O_NONBLOCK) {
 397                         retval = -EAGAIN;
 398                         break;
 399                 }
 400
 401                 if (signal_pending(current)) {
 402                         retval = -ERESTARTSYS;
 403                         break;
 404                 }
 405                 schedule();
 406         } while (1);
 407
 408         __set_current_state(TASK_RUNNING);
 409         remove_wait_queue(&idev->wait, &wait);
 410
 411         return retval;
 412 }
 413
 414 static int uio_find_mem_index(struct vm_area_struct *vma)
 415 {
 416         int mi;
 417         struct uio_device *idev = vma->vm_private_data;
 418
 419         for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
 420                 if (idev->info->mem[mi].size == 0)
 421                         return -1;
 422                 if (vma->vm_pgoff == mi)
 423                         return mi;
 424         }
 425         return -1;
 426 }
 427
 428 static void uio_vma_open(struct vm_area_struct *vma)
 429 {
 430         struct uio_device *idev = vma->vm_private_data;
 431         idev->vma_count++;
 432 }
 433
 434 static void uio_vma_close(struct vm_area_struct *vma)
 435 {
 436         struct uio_device *idev = vma->vm_private_data;
 437         idev->vma_count--;
 438 }
 439
 440 static int uio_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 441 {
 442         struct uio_device *idev = vma->vm_private_data;
 443         struct page *page;
 444
 445         int mi = uio_find_mem_index(vma);
 446         if (mi < 0)
 447                 return VM_FAULT_SIGBUS;
 448
 449         if (idev->info->mem[mi].memtype == UIO_MEM_LOGICAL)
 450                 page = virt_to_page(idev->info->mem[mi].addr);
 451         else
 452                 page = vmalloc_to_page((void*)idev->info->mem[mi].addr);
 453         get_page(page);
 454         vmf->page = page;
 455         return 0;
 456 }
 457
 458 static struct vm_operations_struct uio_vm_ops = {
 459         .open = uio_vma_open,
 460         .close = uio_vma_close,
 461         .fault = uio_vma_fault,
 462 };
 463
 464 static int uio_mmap_physical(struct vm_area_struct *vma)
 465 {
 466         struct uio_device *idev = vma->vm_private_data;
 467         int mi = uio_find_mem_index(vma);
 468         if (mi < 0)
 469                 return -EINVAL;
 470
 471         vma->vm_flags |= VM_IO | VM_RESERVED;
 472
 473         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 474
 475         return remap_pfn_range(vma,
 476                                vma->vm_start,
 477                                idev->info->mem[mi].addr >> PAGE_SHIFT,
 478                                vma->vm_end - vma->vm_start,
 479                                vma->vm_page_prot);
 480 }
 481
 482 static int uio_mmap_logical(struct vm_area_struct *vma)
 483 {
 484         vma->vm_flags |= VM_RESERVED;
 485         vma->vm_ops = &uio_vm_ops;
 486         uio_vma_open(vma);
 487         return 0;
 488 }
 489
 490 static int uio_mmap(struct file *filep, struct vm_area_struct *vma)
 491 {
 492         struct uio_listener *listener = filep->private_data;
 493         struct uio_device *idev = listener->dev;
 494         int mi;
 495         unsigned long requested_pages, actual_pages;
 496         int ret = 0;
 497
 498         if (vma->vm_end < vma->vm_start)
 499                 return -EINVAL;
 500
 501         vma->vm_private_data = idev;
 502
 503         mi = uio_find_mem_index(vma);
 504         if (mi < 0)
 505                 return -EINVAL;
 506
 507         requested_pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 508         actual_pages = (idev->info->mem[mi].size + PAGE_SIZE -1) >> PAGE_SHIFT;
 509         if (requested_pages > actual_pages)
 510                 return -EINVAL;
 511
 512         if (idev->info->mmap) {
 513                 if (!try_module_get(idev->owner))
 514                         return -ENODEV;
 515                 ret = idev->info->mmap(idev->info, vma);
 516                 module_put(idev->owner);
 517                 return ret;
 518         }
 519
 520         switch (idev->info->mem[mi].memtype) {
 521                 case UIO_MEM_PHYS:
 522                         return uio_mmap_physical(vma);
 523                 case UIO_MEM_LOGICAL:
 524                 case UIO_MEM_VIRTUAL:
 525                         return uio_mmap_logical(vma);
 526                 default:
 527                         return -EINVAL;
 528         }
 529 }
 530
 531 static const struct file_operations uio_fops = {
 532         .owner          = THIS_MODULE,
 533         .open           = uio_open,
 534         .release        = uio_release,
 535         .read           = uio_read,
 536         .mmap           = uio_mmap,
 537         .poll           = uio_poll,
 538         .fasync         = uio_fasync,
 539 };
 540
 541 static int uio_major_init(void)
 542 {
 543         uio_major = register_chrdev(0, "uio", &uio_fops);
 544         if (uio_major < 0)
 545                 return uio_major;
 546         return 0;
 547 }
 548
 549 static void uio_major_cleanup(void)
 550 {
 551         unregister_chrdev(uio_major, "uio");
 552 }
 553
 554 static int init_uio_class(void)
 555 {
 556         int ret = 0;
 557
 558         if (uio_class != NULL) {
 559                 kref_get(&uio_class->kref);
 560                 goto exit;
 561         }
 562
 563         /* This is the first time in here, set everything up properly */
 564         ret = uio_major_init();
 565         if (ret)
 566                 goto exit;
 567
 568         uio_class = kzalloc(sizeof(*uio_class), GFP_KERNEL);
 569         if (!uio_class) {
 570                 ret = -ENOMEM;
 571                 goto err_kzalloc;
 572         }
 573
 574         kref_init(&uio_class->kref);
 575         uio_class->class = class_create(THIS_MODULE, "uio");
 576         if (IS_ERR(uio_class->class)) {
 577                 ret = IS_ERR(uio_class->class);
 578                 printk(KERN_ERR "class_create failed for uio\n");
 579                 goto err_class_create;
 580         }
 581         return 0;
 582
 583 err_class_create:
 584         kfree(uio_class);
 585         uio_class = NULL;
 586 err_kzalloc:
 587         uio_major_cleanup();
 588 exit:
 589         return ret;
 590 }
 591
 592 static void release_uio_class(struct kref *kref)
 593 {
 594         /* Ok, we cheat as we know we only have one uio_class */
 595         class_destroy(uio_class->class);
 596         kfree(uio_class);
 597         uio_major_cleanup();
 598         uio_class = NULL;
 599 }
 600
 601 static void uio_class_destroy(void)
 602 {
 603         if (uio_class)
 604                 kref_put(&uio_class->kref, release_uio_class);
 605 }
 606
 607 /**
 608  * uio_register_device - register a new userspace IO device
 609  * @owner:      module that creates the new device
 610  * @parent:     parent device
 611  * @info:       UIO device capabilities
 612  *
 613  * returns zero on success or a negative error code.
 614  */
 615 int __uio_register_device(struct module *owner,
 616                           struct device *parent,
 617                           struct uio_info *info)
 618 {
 619         struct uio_device *idev;
 620         int ret = 0;
 621
 622         if (!parent || !info || !info->name || !info->version)
 623                 return -EINVAL;
 624
 625         info->uio_dev = NULL;
 626
 627         ret = init_uio_class();
 628         if (ret)
 629                 return ret;
 630
 631         idev = kzalloc(sizeof(*idev), GFP_KERNEL);
 632         if (!idev) {
 633                 ret = -ENOMEM;
 634                 goto err_kzalloc;
 635         }
 636
 637         idev->owner = owner;
 638         idev->info = info;
 639         init_waitqueue_head(&idev->wait);
 640         atomic_set(&idev->event, 0);
 641
 642         ret = uio_get_minor(idev);
 643         if (ret)
 644                 goto err_get_minor;
 645
 646         idev->dev = device_create(uio_class->class, parent,
 647                                   MKDEV(uio_major, idev->minor),
 648                                   "uio%d", idev->minor);
 649         if (IS_ERR(idev->dev)) {
 650                 printk(KERN_ERR "UIO: device register failed\n");
 651                 ret = PTR_ERR(idev->dev);
 652                 goto err_device_create;
 653         }
 654         dev_set_drvdata(idev->dev, idev);
 655
 656         ret = uio_dev_add_attributes(idev);
 657         if (ret)
 658                 goto err_uio_dev_add_attributes;
 659
 660         info->uio_dev = idev;
 661
 662         if (idev->info->irq >= 0) {
 663                 ret = request_irq(idev->info->irq, uio_interrupt,
 664                                   idev->info->irq_flags, idev->info->name, idev);
 665                 if (ret)
 666                         goto err_request_irq;
 667         }
 668
 669         return 0;
 670
 671 err_request_irq:
 672         uio_dev_del_attributes(idev);
 673 err_uio_dev_add_attributes:
 674         device_destroy(uio_class->class, MKDEV(uio_major, idev->minor));
 675 err_device_create:
 676         uio_free_minor(idev);
 677 err_get_minor:
 678         kfree(idev);
 679 err_kzalloc:
 680         uio_class_destroy();
 681         return ret;
 682 }
 683 EXPORT_SYMBOL_GPL(__uio_register_device);
 684
 685 /**
 686  * uio_unregister_device - unregister a industrial IO device
 687  * @info:       UIO device capabilities
 688  *
 689  */
 690 void uio_unregister_device(struct uio_info *info)
 691 {
 692         struct uio_device *idev;
 693
 694         if (!info || !info->uio_dev)
 695                 return;
 696
 697         idev = info->uio_dev;
 698
 699         uio_free_minor(idev);
 700
 701         if (info->irq >= 0)
 702                 free_irq(info->irq, idev);
 703
 704         uio_dev_del_attributes(idev);
 705
 706         dev_set_drvdata(idev->dev, NULL);
 707         device_destroy(uio_class->class, MKDEV(uio_major, idev->minor));
 708         kfree(idev);
 709         uio_class_destroy();
 710
 711         return;
 712 }
 713 EXPORT_SYMBOL_GPL(uio_unregister_device);
 714
 715 static int __init uio_init(void)
 716 {
 717         return 0;
 718 }
 719
 720 static void __exit uio_exit(void)
 721 {
 722 }
 723
 724 module_init(uio_init)
 725 module_exit(uio_exit)
 726 MODULE_LICENSE("GPL v2");