drivers/usb/usb-skeleton.c

   1 /*
   2  * USB Skeleton driver - 2.2
   3  *
   4  * Copyright (C) 2001-2004 Greg Kroah-Hartman (greg@kroah.com)
   5  *
   6  *      This program is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU General Public License as
   8  *      published by the Free Software Foundation, version 2.
   9  *
  10  * This driver is based on the 2.6.3 version of drivers/usb/usb-skeleton.c
  11  * but has been rewritten to be easier to read and use.
  12  *
  13  */
  14
  15 #include <linux/kernel.h>
  16 #include <linux/errno.h>
  17 #include <linux/init.h>
  18 #include <linux/slab.h>
  19 #include <linux/module.h>
  20 #include <linux/kref.h>
  21 #include <asm/uaccess.h>
  22 #include <linux/usb.h>
  23 #include <linux/mutex.h>
  24
  25
  26 /* Define these values to match your devices */
  27 #define USB_SKEL_VENDOR_ID      0xfff0
  28 #define USB_SKEL_PRODUCT_ID     0xfff0
  29
  30 /* table of devices that work with this driver */
  31 static struct usb_device_id skel_table [] = {
  32         { USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },
  33         { }                                     /* Terminating entry */
  34 };
  35 MODULE_DEVICE_TABLE(usb, skel_table);
  36
  37
  38 /* Get a minor range for your devices from the usb maintainer */
  39 #define USB_SKEL_MINOR_BASE     192
  40
  41 /* our private defines. if this grows any larger, use your own .h file */
  42 #define MAX_TRANSFER            (PAGE_SIZE - 512)
  43 /* MAX_TRANSFER is chosen so that the VM is not stressed by
  44    allocations > PAGE_SIZE and the number of packets in a page
  45    is an integer 512 is the largest possible packet on EHCI */
  46 #define WRITES_IN_FLIGHT        8
  47 /* arbitrarily chosen */
  48
  49 /* Structure to hold all of our device specific stuff */
  50 struct usb_skel {
  51         struct usb_device       *udev;                  /* the usb device for this device */
  52         struct usb_interface    *interface;             /* the interface for this device */
  53         struct semaphore        limit_sem;              /* limiting the number of writes in progress */
  54         struct usb_anchor       submitted;              /* in case we need to retract our submissions */
  55         struct urb              *bulk_in_urb;           /* the urb to read data with */
  56         unsigned char           *bulk_in_buffer;        /* the buffer to receive data */
  57         size_t                  bulk_in_size;           /* the size of the receive buffer */
  58         size_t                  bulk_in_filled;         /* number of bytes in the buffer */
  59         size_t                  bulk_in_copied;         /* already copied to user space */
  60         __u8                    bulk_in_endpointAddr;   /* the address of the bulk in endpoint */
  61         __u8                    bulk_out_endpointAddr;  /* the address of the bulk out endpoint */
  62         int                     errors;                 /* the last request tanked */
  63         int                     open_count;             /* count the number of openers */
  64         bool                    ongoing_read;           /* a read is going on */
  65         bool                    processed_urb;          /* indicates we haven't processed the urb */
  66         spinlock_t              err_lock;               /* lock for errors */
  67         struct kref             kref;
  68         struct mutex            io_mutex;               /* synchronize I/O with disconnect */
  69         struct completion       bulk_in_completion;     /* to wait for an ongoing read */
  70 };
  71 #define to_skel_dev(d) container_of(d, struct usb_skel, kref)
  72
  73 static struct usb_driver skel_driver;
  74 static void skel_draw_down(struct usb_skel *dev);
  75
  76 static void skel_delete(struct kref *kref)
  77 {
  78         struct usb_skel *dev = to_skel_dev(kref);
  79
  80         usb_free_urb(dev->bulk_in_urb);
  81         usb_put_dev(dev->udev);
  82         kfree(dev->bulk_in_buffer);
  83         kfree(dev);
  84 }
  85
  86 static int skel_open(struct inode *inode, struct file *file)
  87 {
  88         struct usb_skel *dev;
  89         struct usb_interface *interface;
  90         int subminor;
  91         int retval = 0;
  92
  93         subminor = iminor(inode);
  94
  95         interface = usb_find_interface(&skel_driver, subminor);
  96         if (!interface) {
  97                 err ("%s - error, can't find device for minor %d",
  98                      __func__, subminor);
  99                 retval = -ENODEV;
 100                 goto exit;
 101         }
 102
 103         dev = usb_get_intfdata(interface);
 104         if (!dev) {
 105                 retval = -ENODEV;
 106                 goto exit;
 107         }
 108
 109         /* increment our usage count for the device */
 110         kref_get(&dev->kref);
 111
 112         /* lock the device to allow correctly handling errors
 113          * in resumption */
 114         mutex_lock(&dev->io_mutex);
 115
 116         if (!dev->open_count++) {
 117                 retval = usb_autopm_get_interface(interface);
 118                         if (retval) {
 119                                 dev->open_count--;
 120                                 mutex_unlock(&dev->io_mutex);
 121                                 kref_put(&dev->kref, skel_delete);
 122                                 goto exit;
 123                         }
 124         } /* else { //uncomment this block if you want exclusive open
 125                 retval = -EBUSY;
 126                 dev->open_count--;
 127                 mutex_unlock(&dev->io_mutex);
 128                 kref_put(&dev->kref, skel_delete);
 129                 goto exit;
 130         } */
 131         /* prevent the device from being autosuspended */
 132
 133         /* save our object in the file's private structure */
 134         file->private_data = dev;
 135         mutex_unlock(&dev->io_mutex);
 136
 137 exit:
 138         return retval;
 139 }
 140
 141 static int skel_release(struct inode *inode, struct file *file)
 142 {
 143         struct usb_skel *dev;
 144
 145         dev = (struct usb_skel *)file->private_data;
 146         if (dev == NULL)
 147                 return -ENODEV;
 148
 149         /* allow the device to be autosuspended */
 150         mutex_lock(&dev->io_mutex);
 151         if (!--dev->open_count && dev->interface)
 152                 usb_autopm_put_interface(dev->interface);
 153         mutex_unlock(&dev->io_mutex);
 154
 155         /* decrement the count on our device */
 156         kref_put(&dev->kref, skel_delete);
 157         return 0;
 158 }
 159
 160 static int skel_flush(struct file *file, fl_owner_t id)
 161 {
 162         struct usb_skel *dev;
 163         int res;
 164
 165         dev = (struct usb_skel *)file->private_data;
 166         if (dev == NULL)
 167                 return -ENODEV;
 168
 169         /* wait for io to stop */
 170         mutex_lock(&dev->io_mutex);
 171         skel_draw_down(dev);
 172
 173         /* read out errors, leave subsequent opens a clean slate */
 174         spin_lock_irq(&dev->err_lock);
 175         res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0;
 176         dev->errors = 0;
 177         spin_unlock_irq(&dev->err_lock);
 178
 179         mutex_unlock(&dev->io_mutex);
 180
 181         return res;
 182 }
 183
 184 static void skel_read_bulk_callback(struct urb *urb)
 185 {
 186         struct usb_skel *dev;
 187
 188         dev = urb->context;
 189
 190         spin_lock(&dev->err_lock);
 191         /* sync/async unlink faults aren't errors */
 192         if (urb->status) {
 193                 if(!(urb->status == -ENOENT ||
 194                     urb->status == -ECONNRESET ||
 195                     urb->status == -ESHUTDOWN))
 196                         err("%s - nonzero write bulk status received: %d",
 197                             __func__, urb->status);
 198
 199                 dev->errors = urb->status;
 200         } else {
 201                 dev->bulk_in_filled = urb->actual_length;
 202         }
 203         dev->ongoing_read = 0;
 204         spin_unlock(&dev->err_lock);
 205
 206         complete(&dev->bulk_in_completion);
 207 }
 208
 209 static int skel_do_read_io(struct usb_skel *dev, size_t count)
 210 {
 211         int rv;
 212
 213         /* prepare a read */
 214         usb_fill_bulk_urb(dev->bulk_in_urb,
 215                         dev->udev,
 216                         usb_rcvbulkpipe(dev->udev,
 217                                 dev->bulk_in_endpointAddr),
 218                         dev->bulk_in_buffer,
 219                         min(dev->bulk_in_size, count),
 220                         skel_read_bulk_callback,
 221                         dev);
 222         /* tell everybody to leave the URB alone */
 223         spin_lock_irq(&dev->err_lock);
 224         dev->ongoing_read = 1;
 225         spin_unlock_irq(&dev->err_lock);
 226
 227         /* do it */
 228         rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL);
 229         if (rv < 0) {
 230                 err("%s - failed submitting read urb, error %d",
 231                         __func__, rv);
 232                 dev->bulk_in_filled = 0;
 233                 rv = (rv == -ENOMEM) ? rv : -EIO;
 234                 spin_lock_irq(&dev->err_lock);
 235                 dev->ongoing_read = 0;
 236                 spin_unlock_irq(&dev->err_lock);
 237         }
 238
 239         return rv;
 240 }
 241
 242 static ssize_t skel_read(struct file *file, char *buffer, size_t count, loff_t *ppos)
 243 {
 244         struct usb_skel *dev;
 245         int rv;
 246         bool ongoing_io;
 247
 248         dev = (struct usb_skel *)file->private_data;
 249
 250         /* if we cannot read at all, return EOF */
 251         if (!dev->bulk_in_urb || !count)
 252                 return 0;
 253
 254         /* no concurrent readers */
 255         rv = mutex_lock_interruptible(&dev->io_mutex);
 256         if (rv < 0)
 257                 return rv;
 258
 259         if (!dev->interface) {          /* disconnect() was called */
 260                 rv = -ENODEV;
 261                 goto exit;
 262         }
 263
 264         /* if IO is under way, we must not touch things */
 265 retry:
 266         spin_lock_irq(&dev->err_lock);
 267         ongoing_io = dev->ongoing_read;
 268         spin_unlock_irq(&dev->err_lock);
 269
 270         if (ongoing_io) {
 271                 /*
 272                  * IO may take forever
 273                  * hence wait in an interruptible state
 274                  */
 275                 rv = wait_for_completion_interruptible(&dev->bulk_in_completion);
 276                 if (rv < 0)
 277                         goto exit;
 278                 /*
 279                  * by waiting we also semiprocessed the urb
 280                  * we must finish now
 281                  */
 282                 dev->bulk_in_copied = 0;
 283                 dev->processed_urb = 1;
 284         }
 285
 286         if (!dev->processed_urb) {
 287                 /*
 288                  * the URB hasn't been processed
 289                  * do it now
 290                  */
 291                 wait_for_completion(&dev->bulk_in_completion);
 292                 dev->bulk_in_copied = 0;
 293                 dev->processed_urb = 1;
 294         }
 295
 296         /* errors must be reported */
 297         if ((rv = dev->errors) < 0) {
 298                 /* any error is reported once */
 299                 dev->errors = 0;
 300                 /* to preserve notifications about reset */
 301                 rv = (rv == -EPIPE) ? rv : -EIO;
 302                 /* no data to deliver */
 303                 dev->bulk_in_filled = 0;
 304                 /* report it */
 305                 goto exit;
 306         }
 307
 308         /*
 309          * if the buffer is filled we may satisfy the read
 310          * else we need to start IO
 311          */
 312
 313         if (dev->bulk_in_filled) {
 314                 /* we had read data */
 315                 size_t available = dev->bulk_in_filled - dev->bulk_in_copied;
 316                 size_t chunk = min(available, count);
 317
 318                 if (!available) {
 319                         /*
 320                          * all data has been used
 321                          * actual IO needs to be done
 322                          */
 323                         rv = skel_do_read_io(dev, count);
 324                         if (rv < 0)
 325                                 goto exit;
 326                         else
 327                                 goto retry;
 328                 }
 329                 /*
 330                  * data is available
 331                  * chunk tells us how much shall be copied
 332                  */
 333
 334                 if (copy_to_user(buffer,
 335                                  dev->bulk_in_buffer + dev->bulk_in_copied,
 336                                  chunk))
 337                         rv = -EFAULT;
 338                 else
 339                         rv = chunk;
 340
 341                 dev->bulk_in_copied += chunk;
 342
 343                 /*
 344                  * if we are asked for more than we have,
 345                  * we start IO but don't wait
 346                  */
 347                 if (available < count)
 348                         skel_do_read_io(dev, count - chunk);
 349         } else {
 350                 /* no data in the buffer */
 351                 rv = skel_do_read_io(dev, count);
 352                 if (rv < 0)
 353                         goto exit;
 354                 else
 355                         goto retry;
 356         }
 357 exit:
 358         mutex_unlock(&dev->io_mutex);
 359         return rv;
 360 }
 361
 362 static void skel_write_bulk_callback(struct urb *urb)
 363 {
 364         struct usb_skel *dev;
 365
 366         dev = urb->context;
 367
 368         /* sync/async unlink faults aren't errors */
 369         if (urb->status) {
 370                 if(!(urb->status == -ENOENT ||
 371                     urb->status == -ECONNRESET ||
 372                     urb->status == -ESHUTDOWN))
 373                         err("%s - nonzero write bulk status received: %d",
 374                             __func__, urb->status);
 375
 376                 spin_lock(&dev->err_lock);
 377                 dev->errors = urb->status;
 378                 spin_unlock(&dev->err_lock);
 379         }
 380
 381         /* free up our allocated buffer */
 382         usb_buffer_free(urb->dev, urb->transfer_buffer_length,
 383                         urb->transfer_buffer, urb->transfer_dma);
 384         up(&dev->limit_sem);
 385 }
 386
 387 static ssize_t skel_write(struct file *file, const char *user_buffer, size_t count, loff_t *ppos)
 388 {
 389         struct usb_skel *dev;
 390         int retval = 0;
 391         struct urb *urb = NULL;
 392         char *buf = NULL;
 393         size_t writesize = min(count, (size_t)MAX_TRANSFER);
 394
 395         dev = (struct usb_skel *)file->private_data;
 396
 397         /* verify that we actually have some data to write */
 398         if (count == 0)
 399                 goto exit;
 400
 401         /* limit the number of URBs in flight to stop a user from using up all RAM */
 402         if (down_interruptible(&dev->limit_sem)) {
 403                 retval = -ERESTARTSYS;
 404                 goto exit;
 405         }
 406
 407         spin_lock_irq(&dev->err_lock);
 408         if ((retval = dev->errors) < 0) {
 409                 /* any error is reported once */
 410                 dev->errors = 0;
 411                 /* to preserve notifications about reset */
 412                 retval = (retval == -EPIPE) ? retval : -EIO;
 413         }
 414         spin_unlock_irq(&dev->err_lock);
 415         if (retval < 0)
 416                 goto error;
 417
 418         /* create a urb, and a buffer for it, and copy the data to the urb */
 419         urb = usb_alloc_urb(0, GFP_KERNEL);
 420         if (!urb) {
 421                 retval = -ENOMEM;
 422                 goto error;
 423         }
 424
 425         buf = usb_buffer_alloc(dev->udev, writesize, GFP_KERNEL, &urb->transfer_dma);
 426         if (!buf) {
 427                 retval = -ENOMEM;
 428                 goto error;
 429         }
 430
 431         if (copy_from_user(buf, user_buffer, writesize)) {
 432                 retval = -EFAULT;
 433                 goto error;
 434         }
 435
 436         /* this lock makes sure we don't submit URBs to gone devices */
 437         mutex_lock(&dev->io_mutex);
 438         if (!dev->interface) {          /* disconnect() was called */
 439                 mutex_unlock(&dev->io_mutex);
 440                 retval = -ENODEV;
 441                 goto error;
 442         }
 443
 444         /* initialize the urb properly */
 445         usb_fill_bulk_urb(urb, dev->udev,
 446                           usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
 447                           buf, writesize, skel_write_bulk_callback, dev);
 448         urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 449         usb_anchor_urb(urb, &dev->submitted);
 450
 451         /* send the data out the bulk port */
 452         retval = usb_submit_urb(urb, GFP_KERNEL);
 453         mutex_unlock(&dev->io_mutex);
 454         if (retval) {
 455                 err("%s - failed submitting write urb, error %d", __func__, retval);
 456                 goto error_unanchor;
 457         }
 458
 459         /* release our reference to this urb, the USB core will eventually free it entirely */
 460         usb_free_urb(urb);
 461
 462
 463         return writesize;
 464
 465 error_unanchor:
 466         usb_unanchor_urb(urb);
 467 error:
 468         if (urb) {
 469                 usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma);
 470                 usb_free_urb(urb);
 471         }
 472         up(&dev->limit_sem);
 473
 474 exit:
 475         return retval;
 476 }
 477
 478 static const struct file_operations skel_fops = {
 479         .owner =        THIS_MODULE,
 480         .read =         skel_read,
 481         .write =        skel_write,
 482         .open =         skel_open,
 483         .release =      skel_release,
 484         .flush =        skel_flush,
 485 };
 486
 487 /*
 488  * usb class driver info in order to get a minor number from the usb core,
 489  * and to have the device registered with the driver core
 490  */
 491 static struct usb_class_driver skel_class = {
 492         .name =         "skel%d",
 493         .fops =         &skel_fops,
 494         .minor_base =   USB_SKEL_MINOR_BASE,
 495 };
 496
 497 static int skel_probe(struct usb_interface *interface, const struct usb_device_id *id)
 498 {
 499         struct usb_skel *dev;
 500         struct usb_host_interface *iface_desc;
 501         struct usb_endpoint_descriptor *endpoint;
 502         size_t buffer_size;
 503         int i;
 504         int retval = -ENOMEM;
 505
 506         /* allocate memory for our device state and initialize it */
 507         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 508         if (!dev) {
 509                 err("Out of memory");
 510                 goto error;
 511         }
 512         kref_init(&dev->kref);
 513         sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
 514         mutex_init(&dev->io_mutex);
 515         spin_lock_init(&dev->err_lock);
 516         init_usb_anchor(&dev->submitted);
 517         init_completion(&dev->bulk_in_completion);
 518
 519         dev->udev = usb_get_dev(interface_to_usbdev(interface));
 520         dev->interface = interface;
 521
 522         /* set up the endpoint information */
 523         /* use only the first bulk-in and bulk-out endpoints */
 524         iface_desc = interface->cur_altsetting;
 525         for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
 526                 endpoint = &iface_desc->endpoint[i].desc;
 527
 528                 if (!dev->bulk_in_endpointAddr &&
 529                     usb_endpoint_is_bulk_in(endpoint)) {
 530                         /* we found a bulk in endpoint */
 531                         buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
 532                         dev->bulk_in_size = buffer_size;
 533                         dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
 534                         dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
 535                         if (!dev->bulk_in_buffer) {
 536                                 err("Could not allocate bulk_in_buffer");
 537                                 goto error;
 538                         }
 539                         dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL);
 540                         if (!dev->bulk_in_urb) {
 541                                 err("Could not allocate bulk_in_urb");
 542                                 goto error;
 543                         }
 544                 }
 545
 546                 if (!dev->bulk_out_endpointAddr &&
 547                     usb_endpoint_is_bulk_out(endpoint)) {
 548                         /* we found a bulk out endpoint */
 549                         dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
 550                 }
 551         }
 552         if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
 553                 err("Could not find both bulk-in and bulk-out endpoints");
 554                 goto error;
 555         }
 556
 557         /* save our data pointer in this interface device */
 558         usb_set_intfdata(interface, dev);
 559
 560         /* we can register the device now, as it is ready */
 561         retval = usb_register_dev(interface, &skel_class);
 562         if (retval) {
 563                 /* something prevented us from registering this driver */
 564                 err("Not able to get a minor for this device.");
 565                 usb_set_intfdata(interface, NULL);
 566                 goto error;
 567         }
 568
 569         /* let the user know what node this device is now attached to */
 570         dev_info(&interface->dev,
 571                  "USB Skeleton device now attached to USBSkel-%d",
 572                  interface->minor);
 573         return 0;
 574
 575 error:
 576         if (dev)
 577                 /* this frees allocated memory */
 578                 kref_put(&dev->kref, skel_delete);
 579         return retval;
 580 }
 581
 582 static void skel_disconnect(struct usb_interface *interface)
 583 {
 584         struct usb_skel *dev;
 585         int minor = interface->minor;
 586
 587         dev = usb_get_intfdata(interface);
 588         usb_set_intfdata(interface, NULL);
 589
 590         /* give back our minor */
 591         usb_deregister_dev(interface, &skel_class);
 592
 593         /* prevent more I/O from starting */
 594         mutex_lock(&dev->io_mutex);
 595         dev->interface = NULL;
 596         mutex_unlock(&dev->io_mutex);
 597
 598         usb_kill_anchored_urbs(&dev->submitted);
 599
 600         /* decrement our usage count */
 601         kref_put(&dev->kref, skel_delete);
 602
 603         dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);
 604 }
 605
 606 static void skel_draw_down(struct usb_skel *dev)
 607 {
 608         int time;
 609
 610         time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
 611         if (!time)
 612                 usb_kill_anchored_urbs(&dev->submitted);
 613         usb_kill_urb(dev->bulk_in_urb);
 614 }
 615
 616 static int skel_suspend(struct usb_interface *intf, pm_message_t message)
 617 {
 618         struct usb_skel *dev = usb_get_intfdata(intf);
 619
 620         if (!dev)
 621                 return 0;
 622         skel_draw_down(dev);
 623         return 0;
 624 }
 625
 626 static int skel_resume (struct usb_interface *intf)
 627 {
 628         return 0;
 629 }
 630
 631 static int skel_pre_reset(struct usb_interface *intf)
 632 {
 633         struct usb_skel *dev = usb_get_intfdata(intf);
 634
 635         mutex_lock(&dev->io_mutex);
 636         skel_draw_down(dev);
 637
 638         return 0;
 639 }
 640
 641 static int skel_post_reset(struct usb_interface *intf)
 642 {
 643         struct usb_skel *dev = usb_get_intfdata(intf);
 644
 645         /* we are sure no URBs are active - no locking needed */
 646         dev->errors = -EPIPE;
 647         mutex_unlock(&dev->io_mutex);
 648
 649         return 0;
 650 }
 651
 652 static struct usb_driver skel_driver = {
 653         .name =         "skeleton",
 654         .probe =        skel_probe,
 655         .disconnect =   skel_disconnect,
 656         .suspend =      skel_suspend,
 657         .resume =       skel_resume,
 658         .pre_reset =    skel_pre_reset,
 659         .post_reset =   skel_post_reset,
 660         .id_table =     skel_table,
 661         .supports_autosuspend = 1,
 662 };
 663
 664 static int __init usb_skel_init(void)
 665 {
 666         int result;
 667
 668         /* register this driver with the USB subsystem */
 669         result = usb_register(&skel_driver);
 670         if (result)
 671                 err("usb_register failed. Error number %d", result);
 672
 673         return result;
 674 }
 675
 676 static void __exit usb_skel_exit(void)
 677 {
 678         /* deregister this driver with the USB subsystem */
 679         usb_deregister(&skel_driver);
 680 }
 681
 682 module_init(usb_skel_init);
 683 module_exit(usb_skel_exit);
 684
 685 MODULE_LICENSE("GPL");