drivers/usb/usb-skeleton.c

   1 /*
   2  * USB Skeleton driver - 2.2
   3  *
   4  * Copyright (C) 2001-2004 Greg Kroah-Hartman ([email protected])
   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 <linux/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 static DEFINE_MUTEX(skel_mutex);
  31
  32 /* table of devices that work with this driver */
  33 static const struct usb_device_id skel_table[] = {
  34         { USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },
  35         { }                                     /* Terminating entry */
  36 };
  37 MODULE_DEVICE_TABLE(usb, skel_table);
  38
  39
  40 /* Get a minor range for your devices from the usb maintainer */
  41 #define USB_SKEL_MINOR_BASE     192
  42
  43 /* our private defines. if this grows any larger, use your own .h file */
  44 #define MAX_TRANSFER            (PAGE_SIZE - 512)
  45 /* MAX_TRANSFER is chosen so that the VM is not stressed by
  46    allocations > PAGE_SIZE and the number of packets in a page
  47    is an integer 512 is the largest possible packet on EHCI */
  48 #define WRITES_IN_FLIGHT        8
  49 /* arbitrarily chosen */
  50
  51 /* Structure to hold all of our device specific stuff */
  52 struct usb_skel {
  53         struct usb_device       *udev;                  /* the usb device for this device */
  54         struct usb_interface    *interface;             /* the interface for this device */
  55         struct semaphore        limit_sem;              /* limiting the number of writes in progress */
  56         struct usb_anchor       submitted;              /* in case we need to retract our submissions */
  57         struct urb              *bulk_in_urb;           /* the urb to read data with */
  58         unsigned char           *bulk_in_buffer;        /* the buffer to receive data */
  59         size_t                  bulk_in_size;           /* the size of the receive buffer */
  60         size_t                  bulk_in_filled;         /* number of bytes in the buffer */
  61         size_t                  bulk_in_copied;         /* already copied to user space */
  62         __u8                    bulk_in_endpointAddr;   /* the address of the bulk in endpoint */
  63         __u8                    bulk_out_endpointAddr;  /* the address of the bulk out endpoint */
  64         int                     errors;                 /* the last request tanked */
  65         bool                    ongoing_read;           /* a read is going on */
  66         bool                    processed_urb;          /* indicates we haven't processed the urb */
  67         spinlock_t              err_lock;               /* lock for errors */
  68         struct kref             kref;
  69         struct mutex            io_mutex;               /* synchronize I/O with disconnect */
  70         struct completion       bulk_in_completion;     /* to wait for an ongoing read */
  71 };
  72 #define to_skel_dev(d) container_of(d, struct usb_skel, kref)
  73
  74 static struct usb_driver skel_driver;
  75 static void skel_draw_down(struct usb_skel *dev);
  76
  77 static void skel_delete(struct kref *kref)
  78 {
  79         struct usb_skel *dev = to_skel_dev(kref);
  80
  81         usb_free_urb(dev->bulk_in_urb);
  82         usb_put_dev(dev->udev);
  83         kfree(dev->bulk_in_buffer);
  84         kfree(dev);
  85 }
  86
  87 static int skel_open(struct inode *inode, struct file *file)
  88 {
  89         struct usb_skel *dev;
  90         struct usb_interface *interface;
  91         int subminor;
  92         int retval = 0;
  93
  94         subminor = iminor(inode);
  95
  96         interface = usb_find_interface(&skel_driver, subminor);
  97         if (!interface) {
  98                 err("%s - error, can't find device for minor %d",
  99                      __func__, subminor);
 100                 retval = -ENODEV;
 101                 goto exit;
 102         }
 103
 104         mutex_lock(&skel_mutex);
 105         dev = usb_get_intfdata(interface);
 106         if (!dev) {
 107                 mutex_unlock(&skel_mutex);
 108                 retval = -ENODEV;
 109                 goto exit;
 110         }
 111
 112         /* increment our usage count for the device */
 113         kref_get(&dev->kref);
 114         mutex_unlock(&skel_mutex);
 115
 116         /* lock the device to allow correctly handling errors
 117          * in resumption */
 118         mutex_lock(&dev->io_mutex);
 119         if (!dev->interface) {
 120                 retval = -ENODEV;
 121                 goto out_err;
 122         }
 123
 124         retval = usb_autopm_get_interface(interface);
 125         if (retval)
 126                 goto out_err;
 127
 128         /* save our object in the file's private structure */
 129         file->private_data = dev;
 130
 131 out_err:
 132         mutex_unlock(&dev->io_mutex);
 133         if (retval)
 134                 kref_put(&dev->kref, skel_delete);
 135
 136 exit:
 137         return retval;
 138 }
 139
 140 static int skel_release(struct inode *inode, struct file *file)
 141 {
 142         struct usb_skel *dev;
 143
 144         dev = file->private_data;
 145         if (dev == NULL)
 146                 return -ENODEV;
 147
 148         /* allow the device to be autosuspended */
 149         mutex_lock(&dev->io_mutex);
 150         if (dev->interface)
 151                 usb_autopm_put_interface(dev->interface);
 152         mutex_unlock(&dev->io_mutex);
 153
 154         /* decrement the count on our device */
 155         kref_put(&dev->kref, skel_delete);
 156         return 0;
 157 }
 158
 159 static int skel_flush(struct file *file, fl_owner_t id)
 160 {
 161         struct usb_skel *dev;
 162         int res;
 163
 164         dev = file->private_data;
 165         if (dev == NULL)
 166                 return -ENODEV;
 167
 168         /* wait for io to stop */
 169         mutex_lock(&dev->io_mutex);
 170         skel_draw_down(dev);
 171
 172         /* read out errors, leave subsequent opens a clean slate */
 173         spin_lock_irq(&dev->err_lock);
 174         res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0;
 175         dev->errors = 0;
 176         spin_unlock_irq(&dev->err_lock);
 177
 178         mutex_unlock(&dev->io_mutex);
 179
 180         return res;
 181 }
 182
 183 static void skel_read_bulk_callback(struct urb *urb)
 184 {
 185         struct usb_skel *dev;
 186
 187         dev = urb->context;
 188
 189         spin_lock(&dev->err_lock);
 190         /* sync/async unlink faults aren't errors */
 191         if (urb->status) {
 192                 if (!(urb->status == -ENOENT ||
 193                     urb->status == -ECONNRESET ||
 194                     urb->status == -ESHUTDOWN))
 195                         err("%s - nonzero write bulk status received: %d",
 196                             __func__, urb->status);
 197
 198                 dev->errors = urb->status;
 199         } else {
 200                 dev->bulk_in_filled = urb->actual_length;
 201         }
 202         dev->ongoing_read = 0;
 203         spin_unlock(&dev->err_lock);
 204
 205         complete(&dev->bulk_in_completion);
 206 }
 207
 208 static int skel_do_read_io(struct usb_skel *dev, size_t count)
 209 {
 210         int rv;
 211
 212         /* prepare a read */
 213         usb_fill_bulk_urb(dev->bulk_in_urb,
 214                         dev->udev,
 215                         usb_rcvbulkpipe(dev->udev,
 216                                 dev->bulk_in_endpointAddr),
 217                         dev->bulk_in_buffer,
 218                         min(dev->bulk_in_size, count),
 219                         skel_read_bulk_callback,
 220                         dev);
 221         /* tell everybody to leave the URB alone */
 222         spin_lock_irq(&dev->err_lock);
 223         dev->ongoing_read = 1;
 224         spin_unlock_irq(&dev->err_lock);
 225
 226         /* do it */
 227         rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL);
 228         if (rv < 0) {
 229                 err("%s - failed submitting read urb, error %d",
 230                         __func__, rv);
 231                 dev->bulk_in_filled = 0;
 232                 rv = (rv == -ENOMEM) ? rv : -EIO;
 233                 spin_lock_irq(&dev->err_lock);
 234                 dev->ongoing_read = 0;
 235                 spin_unlock_irq(&dev->err_lock);
 236         }
 237
 238         return rv;
 239 }
 240
 241 static ssize_t skel_read(struct file *file, char *buffer, size_t count,
 242                          loff_t *ppos)
 243 {
 244         struct usb_skel *dev;
 245         int rv;
 246         bool ongoing_io;
 247
 248         dev = 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                 /* nonblocking IO shall not wait */
 272                 if (file->f_flags & O_NONBLOCK) {
 273                         rv = -EAGAIN;
 274                         goto exit;
 275                 }
 276                 /*
 277                  * IO may take forever
 278                  * hence wait in an interruptible state
 279                  */
 280                 rv = wait_for_completion_interruptible(&dev->bulk_in_completion);
 281                 if (rv < 0)
 282                         goto exit;
 283                 /*
 284                  * by waiting we also semiprocessed the urb
 285                  * we must finish now
 286                  */
 287                 dev->bulk_in_copied = 0;
 288                 dev->processed_urb = 1;
 289         }
 290
 291         if (!dev->processed_urb) {
 292                 /*
 293                  * the URB hasn't been processed
 294                  * do it now
 295                  */
 296                 wait_for_completion(&dev->bulk_in_completion);
 297                 dev->bulk_in_copied = 0;
 298                 dev->processed_urb = 1;
 299         }
 300
 301         /* errors must be reported */
 302         rv = dev->errors;
 303         if (rv < 0) {
 304                 /* any error is reported once */
 305                 dev->errors = 0;
 306                 /* to preserve notifications about reset */
 307                 rv = (rv == -EPIPE) ? rv : -EIO;
 308                 /* no data to deliver */
 309                 dev->bulk_in_filled = 0;
 310                 /* report it */
 311                 goto exit;
 312         }
 313
 314         /*
 315          * if the buffer is filled we may satisfy the read
 316          * else we need to start IO
 317          */
 318
 319         if (dev->bulk_in_filled) {
 320                 /* we had read data */
 321                 size_t available = dev->bulk_in_filled - dev->bulk_in_copied;
 322                 size_t chunk = min(available, count);
 323
 324                 if (!available) {
 325                         /*
 326                          * all data has been used
 327                          * actual IO needs to be done
 328                          */
 329                         rv = skel_do_read_io(dev, count);
 330                         if (rv < 0)
 331                                 goto exit;
 332                         else
 333                                 goto retry;
 334                 }
 335                 /*
 336                  * data is available
 337                  * chunk tells us how much shall be copied
 338                  */
 339
 340                 if (copy_to_user(buffer,
 341                                  dev->bulk_in_buffer + dev->bulk_in_copied,
 342                                  chunk))
 343                         rv = -EFAULT;
 344                 else
 345                         rv = chunk;
 346
 347                 dev->bulk_in_copied += chunk;
 348
 349                 /*
 350                  * if we are asked for more than we have,
 351                  * we start IO but don't wait
 352                  */
 353                 if (available < count)
 354                         skel_do_read_io(dev, count - chunk);
 355         } else {
 356                 /* no data in the buffer */
 357                 rv = skel_do_read_io(dev, count);
 358                 if (rv < 0)
 359                         goto exit;
 360                 else if (!(file->f_flags & O_NONBLOCK))
 361                         goto retry;
 362                 rv = -EAGAIN;
 363         }
 364 exit:
 365         mutex_unlock(&dev->io_mutex);
 366         return rv;
 367 }
 368
 369 static void skel_write_bulk_callback(struct urb *urb)
 370 {
 371         struct usb_skel *dev;
 372
 373         dev = urb->context;
 374
 375         /* sync/async unlink faults aren't errors */
 376         if (urb->status) {
 377                 if (!(urb->status == -ENOENT ||
 378                     urb->status == -ECONNRESET ||
 379                     urb->status == -ESHUTDOWN))
 380                         err("%s - nonzero write bulk status received: %d",
 381                             __func__, urb->status);
 382
 383                 spin_lock(&dev->err_lock);
 384                 dev->errors = urb->status;
 385                 spin_unlock(&dev->err_lock);
 386         }
 387
 388         /* free up our allocated buffer */
 389         usb_free_coherent(urb->dev, urb->transfer_buffer_length,
 390                           urb->transfer_buffer, urb->transfer_dma);
 391         up(&dev->limit_sem);
 392 }
 393
 394 static ssize_t skel_write(struct file *file, const char *user_buffer,
 395                           size_t count, loff_t *ppos)
 396 {
 397         struct usb_skel *dev;
 398         int retval = 0;
 399         struct urb *urb = NULL;
 400         char *buf = NULL;
 401         size_t writesize = min(count, (size_t)MAX_TRANSFER);
 402
 403         dev = file->private_data;
 404
 405         /* verify that we actually have some data to write */
 406         if (count == 0)
 407                 goto exit;
 408
 409         /*
 410          * limit the number of URBs in flight to stop a user from using up all
 411          * RAM
 412          */
 413         if (!(file->f_flags & O_NONBLOCK)) {
 414                 if (down_interruptible(&dev->limit_sem)) {
 415                         retval = -ERESTARTSYS;
 416                         goto exit;
 417                 }
 418         } else {
 419                 if (down_trylock(&dev->limit_sem)) {
 420                         retval = -EAGAIN;
 421                         goto exit;
 422                 }
 423         }
 424
 425         spin_lock_irq(&dev->err_lock);
 426         retval = dev->errors;
 427         if (retval < 0) {
 428                 /* any error is reported once */
 429                 dev->errors = 0;
 430                 /* to preserve notifications about reset */
 431                 retval = (retval == -EPIPE) ? retval : -EIO;
 432         }
 433         spin_unlock_irq(&dev->err_lock);
 434         if (retval < 0)
 435                 goto error;
 436
 437         /* create a urb, and a buffer for it, and copy the data to the urb */
 438         urb = usb_alloc_urb(0, GFP_KERNEL);
 439         if (!urb) {
 440                 retval = -ENOMEM;
 441                 goto error;
 442         }
 443
 444         buf = usb_alloc_coherent(dev->udev, writesize, GFP_KERNEL,
 445                                  &urb->transfer_dma);
 446         if (!buf) {
 447                 retval = -ENOMEM;
 448                 goto error;
 449         }
 450
 451         if (copy_from_user(buf, user_buffer, writesize)) {
 452                 retval = -EFAULT;
 453                 goto error;
 454         }
 455
 456         /* this lock makes sure we don't submit URBs to gone devices */
 457         mutex_lock(&dev->io_mutex);
 458         if (!dev->interface) {          /* disconnect() was called */
 459                 mutex_unlock(&dev->io_mutex);
 460                 retval = -ENODEV;
 461                 goto error;
 462         }
 463
 464         /* initialize the urb properly */
 465         usb_fill_bulk_urb(urb, dev->udev,
 466                           usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
 467                           buf, writesize, skel_write_bulk_callback, dev);
 468         urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 469         usb_anchor_urb(urb, &dev->submitted);
 470
 471         /* send the data out the bulk port */
 472         retval = usb_submit_urb(urb, GFP_KERNEL);
 473         mutex_unlock(&dev->io_mutex);
 474         if (retval) {
 475                 err("%s - failed submitting write urb, error %d", __func__,
 476                     retval);
 477                 goto error_unanchor;
 478         }
 479
 480         /*
 481          * release our reference to this urb, the USB core will eventually free
 482          * it entirely
 483          */
 484         usb_free_urb(urb);
 485
 486
 487         return writesize;
 488
 489 error_unanchor:
 490         usb_unanchor_urb(urb);
 491 error:
 492         if (urb) {
 493                 usb_free_coherent(dev->udev, writesize, buf, urb->transfer_dma);
 494                 usb_free_urb(urb);
 495         }
 496         up(&dev->limit_sem);
 497
 498 exit:
 499         return retval;
 500 }
 501
 502 static const struct file_operations skel_fops = {
 503         .owner =        THIS_MODULE,
 504         .read =         skel_read,
 505         .write =        skel_write,
 506         .open =         skel_open,
 507         .release =      skel_release,
 508         .flush =        skel_flush,
 509         .llseek =       noop_llseek,
 510 };
 511
 512 /*
 513  * usb class driver info in order to get a minor number from the usb core,
 514  * and to have the device registered with the driver core
 515  */
 516 static struct usb_class_driver skel_class = {
 517         .name =         "skel%d",
 518         .fops =         &skel_fops,
 519         .minor_base =   USB_SKEL_MINOR_BASE,
 520 };
 521
 522 static int skel_probe(struct usb_interface *interface,
 523                       const struct usb_device_id *id)
 524 {
 525         struct usb_skel *dev;
 526         struct usb_host_interface *iface_desc;
 527         struct usb_endpoint_descriptor *endpoint;
 528         size_t buffer_size;
 529         int i;
 530         int retval = -ENOMEM;
 531
 532         /* allocate memory for our device state and initialize it */
 533         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 534         if (!dev) {
 535                 err("Out of memory");
 536                 goto error;
 537         }
 538         kref_init(&dev->kref);
 539         sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
 540         mutex_init(&dev->io_mutex);
 541         spin_lock_init(&dev->err_lock);
 542         init_usb_anchor(&dev->submitted);
 543         init_completion(&dev->bulk_in_completion);
 544
 545         dev->udev = usb_get_dev(interface_to_usbdev(interface));
 546         dev->interface = interface;
 547
 548         /* set up the endpoint information */
 549         /* use only the first bulk-in and bulk-out endpoints */
 550         iface_desc = interface->cur_altsetting;
 551         for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
 552                 endpoint = &iface_desc->endpoint[i].desc;
 553
 554                 if (!dev->bulk_in_endpointAddr &&
 555                     usb_endpoint_is_bulk_in(endpoint)) {
 556                         /* we found a bulk in endpoint */
 557                         buffer_size = usb_endpoint_maxp(endpoint);
 558                         dev->bulk_in_size = buffer_size;
 559                         dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
 560                         dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
 561                         if (!dev->bulk_in_buffer) {
 562                                 err("Could not allocate bulk_in_buffer");
 563                                 goto error;
 564                         }
 565                         dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL);
 566                         if (!dev->bulk_in_urb) {
 567                                 err("Could not allocate bulk_in_urb");
 568                                 goto error;
 569                         }
 570                 }
 571
 572                 if (!dev->bulk_out_endpointAddr &&
 573                     usb_endpoint_is_bulk_out(endpoint)) {
 574                         /* we found a bulk out endpoint */
 575                         dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
 576                 }
 577         }
 578         if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
 579                 err("Could not find both bulk-in and bulk-out endpoints");
 580                 goto error;
 581         }
 582
 583         /* save our data pointer in this interface device */
 584         usb_set_intfdata(interface, dev);
 585
 586         /* we can register the device now, as it is ready */
 587         retval = usb_register_dev(interface, &skel_class);
 588         if (retval) {
 589                 /* something prevented us from registering this driver */
 590                 err("Not able to get a minor for this device.");
 591                 usb_set_intfdata(interface, NULL);
 592                 goto error;
 593         }
 594
 595         /* let the user know what node this device is now attached to */
 596         dev_info(&interface->dev,
 597                  "USB Skeleton device now attached to USBSkel-%d",
 598                  interface->minor);
 599         return 0;
 600
 601 error:
 602         if (dev)
 603                 /* this frees allocated memory */
 604                 kref_put(&dev->kref, skel_delete);
 605         return retval;
 606 }
 607
 608 static void skel_disconnect(struct usb_interface *interface)
 609 {
 610         struct usb_skel *dev;
 611         int minor = interface->minor;
 612
 613         dev = usb_get_intfdata(interface);
 614
 615         /* give back our minor */
 616         usb_deregister_dev(interface, &skel_class);
 617
 618         /* prevent more I/O from starting */
 619         mutex_lock(&dev->io_mutex);
 620         dev->interface = NULL;
 621         mutex_unlock(&dev->io_mutex);
 622
 623         usb_kill_anchored_urbs(&dev->submitted);
 624
 625         mutex_lock(&skel_mutex);
 626         usb_set_intfdata(interface, NULL);
 627
 628         /* decrement our usage count */
 629         kref_put(&dev->kref, skel_delete);
 630         mutex_unlock(&skel_mutex);
 631
 632         dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);
 633 }
 634
 635 static void skel_draw_down(struct usb_skel *dev)
 636 {
 637         int time;
 638
 639         time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
 640         if (!time)
 641                 usb_kill_anchored_urbs(&dev->submitted);
 642         usb_kill_urb(dev->bulk_in_urb);
 643 }
 644
 645 static int skel_suspend(struct usb_interface *intf, pm_message_t message)
 646 {
 647         struct usb_skel *dev = usb_get_intfdata(intf);
 648
 649         if (!dev)
 650                 return 0;
 651         skel_draw_down(dev);
 652         return 0;
 653 }
 654
 655 static int skel_resume(struct usb_interface *intf)
 656 {
 657         return 0;
 658 }
 659
 660 static int skel_pre_reset(struct usb_interface *intf)
 661 {
 662         struct usb_skel *dev = usb_get_intfdata(intf);
 663
 664         mutex_lock(&dev->io_mutex);
 665         skel_draw_down(dev);
 666
 667         return 0;
 668 }
 669
 670 static int skel_post_reset(struct usb_interface *intf)
 671 {
 672         struct usb_skel *dev = usb_get_intfdata(intf);
 673
 674         /* we are sure no URBs are active - no locking needed */
 675         dev->errors = -EPIPE;
 676         mutex_unlock(&dev->io_mutex);
 677
 678         return 0;
 679 }
 680
 681 static struct usb_driver skel_driver = {
 682         .name =         "skeleton",
 683         .probe =        skel_probe,
 684         .disconnect =   skel_disconnect,
 685         .suspend =      skel_suspend,
 686         .resume =       skel_resume,
 687         .pre_reset =    skel_pre_reset,
 688         .post_reset =   skel_post_reset,
 689         .id_table =     skel_table,
 690         .supports_autosuspend = 1,
 691 };
 692
 693 module_usb_driver(skel_driver);
 694
 695 MODULE_LICENSE("GPL");