drivers/staging/frontier/alphatrack.c

   1 /*
   2  * Frontier Designs Alphatrack driver
   3  *
   4  * Copyright (C) 2007 Michael Taht (m@taht.net)
   5  *
   6  * Based on the usbled driver and ldusb drivers by
   7  *
   8  * Copyright (C) 2004 Greg Kroah-Hartman (greg@kroah.com)
   9  * Copyright (C) 2005 Michael Hund <mhund@ld-didactic.de>
  10  *
  11  * The ldusb driver was, in turn, derived from Lego USB Tower driver
  12  * Copyright (C) 2003 David Glance <advidgsf@sourceforge.net>
  13  *               2001-2004 Juergen Stuber <starblue@users.sourceforge.net>
  14  *
  15  *      This program is free software; you can redistribute it and/or
  16  *      modify it under the terms of the GNU General Public License as
  17  *      published by the Free Software Foundation, version 2.
  18  *
  19  */
  20
  21 /**
  22  * This driver uses a ring buffer for time critical reading of
  23  * interrupt in reports and provides read and write methods for
  24  * raw interrupt reports.
  25  */
  26
  27 /*
  28  * Note: this currently uses a dumb ringbuffer for reads and writes.
  29  * A more optimal driver would cache and kill off outstanding urbs that are
  30  * now invalid, and ignore ones that already were in the queue but valid
  31  * as we only have 30 commands for the alphatrack. In particular this is
  32  * key for getting lights to flash in time as otherwise many commands
  33  * can be buffered up before the light change makes it to the interface.
  34  */
  35
  36 #include <linux/kernel.h>
  37 #include <linux/errno.h>
  38 #include <linux/init.h>
  39 #include <linux/slab.h>
  40 #include <linux/module.h>
  41 #include <linux/kobject.h>
  42 #include <linux/mutex.h>
  43
  44 #include <linux/uaccess.h>
  45 #include <linux/input.h>
  46 #include <linux/usb.h>
  47 #include <linux/poll.h>
  48
  49 #include "alphatrack.h"
  50
  51 #define VENDOR_ID       0x165b
  52 #define PRODUCT_ID      0xfad1
  53
  54 #ifdef CONFIG_USB_DYNAMIC_MINORS
  55 #define USB_ALPHATRACK_MINOR_BASE       0
  56 #else
  57 /* FIXME 176 - is another driver's minor - apply for that */
  58 #define USB_ALPHATRACK_MINOR_BASE       176
  59 #endif
  60
  61 /* table of devices that work with this driver */
  62 static const struct usb_device_id usb_alphatrack_table[] = {
  63         {USB_DEVICE(VENDOR_ID, PRODUCT_ID)},
  64         {}                      /* Terminating entry */
  65 };
  66
  67 MODULE_DEVICE_TABLE(usb, usb_alphatrack_table);
  68 MODULE_VERSION("0.41");
  69 MODULE_AUTHOR("Mike Taht <m@taht.net>");
  70 MODULE_DESCRIPTION("Alphatrack USB Driver");
  71 MODULE_LICENSE("GPL");
  72 MODULE_SUPPORTED_DEVICE("Frontier Designs Alphatrack Control Surface");
  73
  74 /* These aren't done yet */
  75
  76 #define SUPPRESS_EXTRA_ONLINE_EVENTS 0
  77 #define BUFFERED_WRITES 0
  78 #define SUPPRESS_EXTRA_OFFLINE_EVENTS 0
  79 #define COMPRESS_FADER_EVENTS 0
  80
  81 #define BUFFERED_READS 1
  82 #define RING_BUFFER_SIZE 512
  83 #define WRITE_BUFFER_SIZE 34
  84 #define ALPHATRACK_USB_TIMEOUT 10
  85 #define OUTPUT_CMD_SIZE 8
  86 #define INPUT_CMD_SIZE 12
  87 #define ALPHATRACK_DEBUG 0
  88
  89 static int debug = ALPHATRACK_DEBUG;
  90
  91 /* Use our own dbg macro */
  92 #define dbg_info(dev, format, arg...) do \
  93         { if (debug) dev_info(dev , format , ## arg); } while (0)
  94
  95 #define alphatrack_ocmd_info(dev, cmd, format, arg...)
  96
  97 #define alphatrack_icmd_info(dev, cmd, format, arg...)
  98
  99 /* Module parameters */
 100
 101 module_param(debug, int, S_IRUGO | S_IWUSR);
 102 MODULE_PARM_DESC(debug, "Debug enabled or not");
 103
 104 /*
 105  * All interrupt in transfers are collected in a ring buffer to
 106  * avoid racing conditions and get better performance of the driver.
 107  */
 108
 109 static int ring_buffer_size = RING_BUFFER_SIZE;
 110
 111 module_param(ring_buffer_size, int, S_IRUGO);
 112 MODULE_PARM_DESC(ring_buffer_size, "Read ring buffer size");
 113
 114 /* The write_buffer can one day contain more than one interrupt out transfer.*/
 115
 116 static int write_buffer_size = WRITE_BUFFER_SIZE;
 117 module_param(write_buffer_size, int, S_IRUGO);
 118 MODULE_PARM_DESC(write_buffer_size, "Write buffer size");
 119
 120 /*
 121  * Increase the interval for debugging purposes.
 122  * or set to 1 to use the standard interval from the endpoint descriptors.
 123  */
 124
 125 static int min_interrupt_in_interval = ALPHATRACK_USB_TIMEOUT;
 126 module_param(min_interrupt_in_interval, int, 0);
 127 MODULE_PARM_DESC(min_interrupt_in_interval,
 128                  "Minimum interrupt in interval in ms");
 129
 130 static int min_interrupt_out_interval = ALPHATRACK_USB_TIMEOUT;
 131 module_param(min_interrupt_out_interval, int, 0);
 132 MODULE_PARM_DESC(min_interrupt_out_interval,
 133                  "Minimum interrupt out interval in ms");
 134
 135 /* Structure to hold all of our device specific stuff */
 136
 137 struct usb_alphatrack {
 138         struct mutex mtx;       /* locks this structure */
 139         struct usb_interface *intf;     /* save off the usb interface pointer */
 140         int open_count;         /* number of times this port has been opened */
 141
 142         /* make gcc happy */
 143         struct alphatrack_icmd (*ring_buffer)[RING_BUFFER_SIZE];
 144         struct alphatrack_ocmd (*write_buffer)[WRITE_BUFFER_SIZE];
 145         unsigned int ring_head;
 146         unsigned int ring_tail;
 147
 148         wait_queue_head_t read_wait;
 149         wait_queue_head_t write_wait;
 150
 151         unsigned char *interrupt_in_buffer;
 152         unsigned char *oldi_buffer;
 153         struct usb_endpoint_descriptor *interrupt_in_endpoint;
 154         struct urb *interrupt_in_urb;
 155         int interrupt_in_interval;
 156         size_t interrupt_in_endpoint_size;
 157         int interrupt_in_running;
 158         int interrupt_in_done;
 159
 160         char *interrupt_out_buffer;
 161         struct usb_endpoint_descriptor *interrupt_out_endpoint;
 162         struct urb *interrupt_out_urb;
 163         int interrupt_out_interval;
 164         size_t interrupt_out_endpoint_size;
 165         int interrupt_out_busy;
 166
 167         atomic_t writes_pending;
 168         int event;              /* alternate interface to events */
 169         int fader;              /* 10 bits */
 170         int lights;             /* 23 bits */
 171         unsigned char dump_state;       /* 0 if disabled 1 if enabled */
 172         unsigned char enable;   /* 0 if disabled 1 if enabled */
 173         unsigned char offline;  /* if the device is out of range or asleep */
 174         unsigned char verbose;  /* be verbose in error reporting */
 175         unsigned char last_cmd[OUTPUT_CMD_SIZE];
 176         unsigned char screen[32];
 177 };
 178
 179 /* prevent races between open() and disconnect() */
 180 static DEFINE_MUTEX(disconnect_mutex);
 181
 182 /* forward declaration */
 183
 184 static struct usb_driver usb_alphatrack_driver;
 185
 186 /**
 187  *      usb_alphatrack_abort_transfers
 188  *      aborts transfers and frees associated data structures
 189  */
 190 static void usb_alphatrack_abort_transfers(struct usb_alphatrack *dev)
 191 {
 192         /* shutdown transfer */
 193         if (dev->interrupt_in_running) {
 194                 dev->interrupt_in_running = 0;
 195                 if (dev->intf)
 196                         usb_kill_urb(dev->interrupt_in_urb);
 197         }
 198         if (dev->interrupt_out_busy)
 199                 if (dev->intf)
 200                         usb_kill_urb(dev->interrupt_out_urb);
 201 }
 202
 203 /** usb_alphatrack_delete */
 204 static void usb_alphatrack_delete(struct usb_alphatrack *dev)
 205 {
 206         usb_alphatrack_abort_transfers(dev);
 207         usb_free_urb(dev->interrupt_in_urb);
 208         usb_free_urb(dev->interrupt_out_urb);
 209         kfree(dev->ring_buffer);
 210         kfree(dev->interrupt_in_buffer);
 211         kfree(dev->interrupt_out_buffer);
 212         kfree(dev);             /* fixme oldi_buffer */
 213 }
 214
 215 /** usb_alphatrack_interrupt_in_callback */
 216
 217 static void usb_alphatrack_interrupt_in_callback(struct urb *urb)
 218 {
 219         struct usb_alphatrack *dev = urb->context;
 220         unsigned int next_ring_head;
 221         int retval = -1;
 222
 223         if (urb->status) {
 224                 if (urb->status == -ENOENT ||
 225                     urb->status == -ECONNRESET || urb->status == -ESHUTDOWN) {
 226                         goto exit;
 227                 } else {
 228                         dbg_info(&dev->intf->dev,
 229                                  "%s: nonzero status received: %d\n", __func__,
 230                                  urb->status);
 231                         goto resubmit;  /* maybe we can recover */
 232                 }
 233         }
 234
 235         if (urb->actual_length != INPUT_CMD_SIZE) {
 236                 dev_warn(&dev->intf->dev,
 237                          "Urb length was %d bytes!!"
 238                          "Do something intelligent\n", urb->actual_length);
 239         } else {
 240                 alphatrack_ocmd_info(&dev->intf->dev,
 241                                      &(*dev->ring_buffer)[dev->ring_tail].cmd,
 242                                      "%s", "bla");
 243                 if (memcmp
 244                     (dev->interrupt_in_buffer, dev->oldi_buffer,
 245                      INPUT_CMD_SIZE) == 0) {
 246                         goto resubmit;
 247                 }
 248                 memcpy(dev->oldi_buffer, dev->interrupt_in_buffer,
 249                        INPUT_CMD_SIZE);
 250
 251 #if SUPPRESS_EXTRA_OFFLINE_EVENTS
 252                 if (dev->offline == 2 && dev->interrupt_in_buffer[1] == 0xff)
 253                         goto resubmit;
 254                 if (dev->offline == 1 && dev->interrupt_in_buffer[1] == 0xff) {
 255                         dev->offline = 2;
 256                         goto resubmit;
 257                 }
 258 /* Always pass one offline event up the stack */
 259                 if (dev->offline > 0 && dev->interrupt_in_buffer[1] != 0xff)
 260                         dev->offline = 0;
 261                 if (dev->offline == 0 && dev->interrupt_in_buffer[1] == 0xff)
 262                         dev->offline = 1;
 263 #endif
 264                 dbg_info(&dev->intf->dev, "%s: head, tail are %x, %x\n",
 265                          __func__, dev->ring_head, dev->ring_tail);
 266                 next_ring_head = (dev->ring_head + 1) % ring_buffer_size;
 267
 268                 if (next_ring_head != dev->ring_tail) {
 269                         memcpy(&((*dev->ring_buffer)[dev->ring_head]),
 270                                dev->interrupt_in_buffer, urb->actual_length);
 271                         dev->ring_head = next_ring_head;
 272                         retval = 0;
 273                         memset(dev->interrupt_in_buffer, 0, urb->actual_length);
 274                 } else {
 275                         dev_warn(&dev->intf->dev,
 276                                  "Ring buffer overflow, %d bytes dropped\n",
 277                                  urb->actual_length);
 278                         memset(dev->interrupt_in_buffer, 0, urb->actual_length);
 279                 }
 280         }
 281
 282 resubmit:
 283         /* resubmit if we're still running */
 284         if (dev->interrupt_in_running && dev->intf) {
 285                 retval = usb_submit_urb(dev->interrupt_in_urb, GFP_ATOMIC);
 286                 if (retval)
 287                         dev_err(&dev->intf->dev,
 288                                 "usb_submit_urb failed (%d)\n", retval);
 289         }
 290
 291 exit:
 292         dev->interrupt_in_done = 1;
 293         wake_up_interruptible(&dev->read_wait);
 294 }
 295
 296 /** usb_alphatrack_interrupt_out_callback */
 297 static void usb_alphatrack_interrupt_out_callback(struct urb *urb)
 298 {
 299         struct usb_alphatrack *dev = urb->context;
 300
 301         /* sync/async unlink faults aren't errors */
 302         if (urb->status && !(urb->status == -ENOENT ||
 303                              urb->status == -ECONNRESET ||
 304                              urb->status == -ESHUTDOWN))
 305                 dbg_info(&dev->intf->dev,
 306                          "%s - nonzero write interrupt status received: %d\n",
 307                          __func__, urb->status);
 308         atomic_dec(&dev->writes_pending);
 309         dev->interrupt_out_busy = 0;
 310         wake_up_interruptible(&dev->write_wait);
 311 }
 312
 313 /** usb_alphatrack_open */
 314 static int usb_alphatrack_open(struct inode *inode, struct file *file)
 315 {
 316         struct usb_alphatrack *dev;
 317         int subminor;
 318         int retval = 0;
 319         struct usb_interface *interface;
 320
 321         nonseekable_open(inode, file);
 322         subminor = iminor(inode);
 323
 324         mutex_lock(&disconnect_mutex);
 325
 326         interface = usb_find_interface(&usb_alphatrack_driver, subminor);
 327
 328         if (!interface) {
 329                 pr_err("%s - error, can't find device for minor %d\n",
 330                        __func__, subminor);
 331                 retval = -ENODEV;
 332                 goto unlock_disconnect_exit;
 333         }
 334
 335         dev = usb_get_intfdata(interface);
 336
 337         if (!dev) {
 338                 retval = -ENODEV;
 339                 goto unlock_disconnect_exit;
 340         }
 341
 342         /* lock this device */
 343         if (mutex_lock_interruptible(&dev->mtx)) {
 344                 retval = -ERESTARTSYS;
 345                 goto unlock_disconnect_exit;
 346         }
 347
 348         /* allow opening only once */
 349         if (dev->open_count) {
 350                 retval = -EBUSY;
 351                 goto unlock_exit;
 352         }
 353         dev->open_count = 1;
 354
 355         /* initialize in direction */
 356         dev->ring_head = 0;
 357         dev->ring_tail = 0;
 358         usb_fill_int_urb(dev->interrupt_in_urb,
 359                          interface_to_usbdev(interface),
 360                          usb_rcvintpipe(interface_to_usbdev(interface),
 361                                         dev->interrupt_in_endpoint->
 362                                         bEndpointAddress),
 363                          dev->interrupt_in_buffer,
 364                          dev->interrupt_in_endpoint_size,
 365                          usb_alphatrack_interrupt_in_callback, dev,
 366                          dev->interrupt_in_interval);
 367
 368         dev->interrupt_in_running = 1;
 369         dev->interrupt_in_done = 0;
 370         dev->enable = 1;
 371         dev->offline = 0;
 372
 373         retval = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
 374         if (retval) {
 375                 dev_err(&interface->dev,
 376                         "Couldn't submit interrupt_in_urb %d\n", retval);
 377                 dev->interrupt_in_running = 0;
 378                 dev->open_count = 0;
 379                 goto unlock_exit;
 380         }
 381
 382         /* save device in the file's private structure */
 383         file->private_data = dev;
 384
 385 unlock_exit:
 386         mutex_unlock(&dev->mtx);
 387
 388 unlock_disconnect_exit:
 389         mutex_unlock(&disconnect_mutex);
 390
 391         return retval;
 392 }
 393
 394 /** usb_alphatrack_release */
 395 static int usb_alphatrack_release(struct inode *inode, struct file *file)
 396 {
 397         struct usb_alphatrack *dev;
 398         int retval = 0;
 399
 400         dev = file->private_data;
 401
 402         if (dev == NULL) {
 403                 retval = -ENODEV;
 404                 goto exit;
 405         }
 406
 407         if (mutex_lock_interruptible(&dev->mtx)) {
 408                 retval = -ERESTARTSYS;
 409                 goto exit;
 410         }
 411
 412         if (dev->open_count != 1) {
 413                 retval = -ENODEV;
 414                 goto unlock_exit;
 415         }
 416
 417         if (dev->intf == NULL) {
 418                 /* the device was unplugged before the file was released */
 419                 mutex_unlock(&dev->mtx);
 420                 /* unlock here as usb_alphatrack_delete frees dev */
 421                 usb_alphatrack_delete(dev);
 422                 retval = -ENODEV;
 423                 goto exit;
 424         }
 425
 426         /* wait until write transfer is finished */
 427         if (dev->interrupt_out_busy)
 428                 wait_event_interruptible_timeout(dev->write_wait,
 429                                                  !dev->interrupt_out_busy,
 430                                                  2 * HZ);
 431         usb_alphatrack_abort_transfers(dev);
 432         dev->open_count = 0;
 433
 434 unlock_exit:
 435         mutex_unlock(&dev->mtx);
 436
 437 exit:
 438         return retval;
 439 }
 440
 441 /** usb_alphatrack_poll */
 442 static unsigned int usb_alphatrack_poll(struct file *file, poll_table *wait)
 443 {
 444         struct usb_alphatrack *dev;
 445         unsigned int mask = 0;
 446
 447         dev = file->private_data;
 448
 449         poll_wait(file, &dev->read_wait, wait);
 450         poll_wait(file, &dev->write_wait, wait);
 451
 452         if (dev->ring_head != dev->ring_tail)
 453                 mask |= POLLIN | POLLRDNORM;
 454         if (!dev->interrupt_out_busy)
 455                 mask |= POLLOUT | POLLWRNORM;
 456
 457         return mask;
 458 }
 459
 460 /** usb_alphatrack_read */
 461 static ssize_t usb_alphatrack_read(struct file *file, char __user *buffer,
 462                                    size_t count, loff_t *ppos)
 463 {
 464         struct usb_alphatrack *dev;
 465         int retval = 0;
 466
 467         int c = 0;
 468
 469         dev = file->private_data;
 470
 471         /* verify that we actually have some data to read */
 472         if (count == 0)
 473                 goto exit;
 474
 475         /* lock this object */
 476         if (mutex_lock_interruptible(&dev->mtx)) {
 477                 retval = -ERESTARTSYS;
 478                 goto exit;
 479         }
 480
 481         /* verify that the device wasn't unplugged */
 482         if (dev->intf == NULL) {
 483                 retval = -ENODEV;
 484                 pr_err("%s: No device or device unplugged %d\n",
 485                        __func__, retval);
 486                 goto unlock_exit;
 487         }
 488
 489         while (dev->ring_head == dev->ring_tail) {
 490                 if (file->f_flags & O_NONBLOCK) {
 491                         retval = -EAGAIN;
 492                         goto unlock_exit;
 493                 }
 494                 dev->interrupt_in_done = 0;
 495                 retval =
 496                     wait_event_interruptible(dev->read_wait,
 497                                              dev->interrupt_in_done);
 498                 if (retval < 0)
 499                         goto unlock_exit;
 500         }
 501
 502         alphatrack_ocmd_info(&dev->intf->dev,
 503                              &(*dev->ring_buffer)[dev->ring_tail].cmd, "%s",
 504                              ": copying to userspace");
 505
 506         c = 0;
 507         while ((c < count) && (dev->ring_tail != dev->ring_head)) {
 508                 if (copy_to_user
 509                     (&buffer[c], &(*dev->ring_buffer)[dev->ring_tail],
 510                      INPUT_CMD_SIZE)) {
 511                         retval = -EFAULT;
 512                         goto unlock_exit;
 513                 }
 514                 dev->ring_tail = (dev->ring_tail + 1) % ring_buffer_size;
 515                 c += INPUT_CMD_SIZE;
 516                 dbg_info(&dev->intf->dev, "%s: head, tail are %x, %x\n",
 517                          __func__, dev->ring_head, dev->ring_tail);
 518         }
 519         retval = c;
 520
 521 unlock_exit:
 522         /* unlock the device */
 523         mutex_unlock(&dev->mtx);
 524
 525 exit:
 526         return retval;
 527 }
 528
 529 /** usb_alphatrack_write */
 530 static ssize_t usb_alphatrack_write(struct file *file,
 531                                     const char __user *buffer, size_t count,
 532                                     loff_t *ppos)
 533 {
 534         struct usb_alphatrack *dev;
 535         size_t bytes_to_write;
 536         int retval = 0;
 537
 538         dev = file->private_data;
 539
 540         /* verify that we actually have some data to write */
 541         if (count == 0)
 542                 goto exit;
 543
 544         /* lock this object */
 545         if (mutex_lock_interruptible(&dev->mtx)) {
 546                 retval = -ERESTARTSYS;
 547                 goto exit;
 548         }
 549
 550         /* verify that the device wasn't unplugged */
 551         if (dev->intf == NULL) {
 552                 retval = -ENODEV;
 553                 pr_err("%s: No device or device unplugged %d\n",
 554                        __func__, retval);
 555                 goto unlock_exit;
 556         }
 557
 558         /* wait until previous transfer is finished */
 559         if (dev->interrupt_out_busy) {
 560                 if (file->f_flags & O_NONBLOCK) {
 561                         retval = -EAGAIN;
 562                         goto unlock_exit;
 563                 }
 564                 retval =
 565                     wait_event_interruptible(dev->write_wait,
 566                                              !dev->interrupt_out_busy);
 567                 if (retval < 0)
 568                         goto unlock_exit;
 569         }
 570
 571         /* write the data into interrupt_out_buffer from userspace */
 572         /* FIXME - if you write more than 12 bytes this breaks */
 573         bytes_to_write =
 574             min(count, write_buffer_size * dev->interrupt_out_endpoint_size);
 575         if (bytes_to_write < count)
 576                 dev_warn(&dev->intf->dev,
 577                          "Write buffer overflow, %zd bytes dropped\n",
 578                          count - bytes_to_write);
 579
 580         dbg_info(&dev->intf->dev, "%s: count = %zd, bytes_to_write = %zd\n",
 581                  __func__, count, bytes_to_write);
 582
 583         if (copy_from_user(dev->interrupt_out_buffer, buffer, bytes_to_write)) {
 584                 retval = -EFAULT;
 585                 goto unlock_exit;
 586         }
 587
 588         if (dev->interrupt_out_endpoint == NULL) {
 589                 dev_err(&dev->intf->dev, "Endpoint should not be null!\n");
 590                 goto unlock_exit;
 591         }
 592
 593         /* send off the urb */
 594         usb_fill_int_urb(dev->interrupt_out_urb,
 595                          interface_to_usbdev(dev->intf),
 596                          usb_sndintpipe(interface_to_usbdev(dev->intf),
 597                                         dev->interrupt_out_endpoint->
 598                                         bEndpointAddress),
 599                          dev->interrupt_out_buffer, bytes_to_write,
 600                          usb_alphatrack_interrupt_out_callback, dev,
 601                          dev->interrupt_out_interval);
 602         dev->interrupt_out_busy = 1;
 603         atomic_inc(&dev->writes_pending);
 604         wmb();
 605
 606         retval = usb_submit_urb(dev->interrupt_out_urb, GFP_KERNEL);
 607         if (retval) {
 608                 dev->interrupt_out_busy = 0;
 609                 dev_err(&dev->intf->dev,
 610                         "Couldn't submit interrupt_out_urb %d\n", retval);
 611                 atomic_dec(&dev->writes_pending);
 612                 goto unlock_exit;
 613         }
 614         retval = bytes_to_write;
 615
 616 unlock_exit:
 617         /* unlock the device */
 618         mutex_unlock(&dev->mtx);
 619
 620 exit:
 621         return retval;
 622 }
 623
 624 /* file operations needed when we register this driver */
 625 static const struct file_operations usb_alphatrack_fops = {
 626         .owner = THIS_MODULE,
 627         .read = usb_alphatrack_read,
 628         .write = usb_alphatrack_write,
 629         .open = usb_alphatrack_open,
 630         .release = usb_alphatrack_release,
 631         .poll = usb_alphatrack_poll,
 632         .llseek = no_llseek,
 633 };
 634
 635 /*
 636  * usb class driver info in order to get a minor number from the usb core,
 637  * and to have the device registered with the driver core
 638  */
 639
 640 static struct usb_class_driver usb_alphatrack_class = {
 641         .name = "alphatrack%d",
 642         .fops = &usb_alphatrack_fops,
 643         .minor_base = USB_ALPHATRACK_MINOR_BASE,
 644 };
 645
 646 /**
 647  *      usb_alphatrack_probe
 648  *
 649  *      Called by the usb core when a new device is connected that it thinks
 650  *      this driver might be interested in.
 651  */
 652 static int usb_alphatrack_probe(struct usb_interface *intf,
 653                                 const struct usb_device_id *id)
 654 {
 655         struct usb_device *udev = interface_to_usbdev(intf);
 656         struct usb_alphatrack *dev = NULL;
 657         struct usb_host_interface *iface_desc;
 658         struct usb_endpoint_descriptor *endpoint;
 659         int i;
 660         int true_size;
 661         int retval = -ENOMEM;
 662
 663         /* allocate memory for our device state and initialize it */
 664
 665         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 666         if (dev == NULL)
 667                 goto exit;
 668
 669         mutex_init(&dev->mtx);
 670         dev->intf = intf;
 671         init_waitqueue_head(&dev->read_wait);
 672         init_waitqueue_head(&dev->write_wait);
 673
 674         iface_desc = intf->cur_altsetting;
 675
 676         /* set up the endpoint information */
 677         for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
 678                 endpoint = &iface_desc->endpoint[i].desc;
 679
 680                 if (usb_endpoint_is_int_in(endpoint))
 681                         dev->interrupt_in_endpoint = endpoint;
 682
 683                 if (usb_endpoint_is_int_out(endpoint))
 684                         dev->interrupt_out_endpoint = endpoint;
 685         }
 686         if (dev->interrupt_in_endpoint == NULL) {
 687                 dev_err(&intf->dev, "Interrupt in endpoint not found\n");
 688                 goto error;
 689         }
 690         if (dev->interrupt_out_endpoint == NULL)
 691                 dev_warn(&intf->dev,
 692                          "Interrupt out endpoint not found"
 693                          "(using control endpoint instead)\n");
 694
 695         dev->interrupt_in_endpoint_size =
 696             le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize);
 697
 698         if (dev->interrupt_in_endpoint_size != 64)
 699                 dev_warn(&intf->dev, "Interrupt in endpoint size is not 64!\n");
 700
 701         if (ring_buffer_size == 0)
 702                 ring_buffer_size = RING_BUFFER_SIZE;
 703
 704         true_size = min(ring_buffer_size, RING_BUFFER_SIZE);
 705
 706         /*
 707          * FIXME - there are more usb_alloc routines for dma correctness.
 708          * Needed?
 709          */
 710         dev->ring_buffer = kmalloc_array(true_size,
 711                                          sizeof(struct alphatrack_icmd),
 712                                          GFP_KERNEL);
 713         if (!dev->ring_buffer)
 714                 goto error;
 715
 716         dev->interrupt_in_buffer = kmalloc(dev->interrupt_in_endpoint_size,
 717                                            GFP_KERNEL);
 718         if (!dev->interrupt_in_buffer)
 719                 goto error;
 720
 721         dev->oldi_buffer = kmalloc(dev->interrupt_in_endpoint_size, GFP_KERNEL);
 722         if (!dev->oldi_buffer)
 723                 goto error;
 724
 725         dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
 726         if (!dev->interrupt_in_urb) {
 727                 dev_err(&intf->dev, "Couldn't allocate interrupt_in_urb\n");
 728                 goto error;
 729         }
 730
 731         dev->interrupt_out_endpoint_size =
 732             dev->interrupt_out_endpoint ? le16_to_cpu(dev->
 733                                                       interrupt_out_endpoint->
 734                                                       wMaxPacketSize) : udev->
 735             descriptor.bMaxPacketSize0;
 736
 737         if (dev->interrupt_out_endpoint_size != 64)
 738                 dev_warn(&intf->dev,
 739                          "Interrupt out endpoint size is not 64!)\n");
 740
 741         if (write_buffer_size == 0)
 742                 write_buffer_size = WRITE_BUFFER_SIZE;
 743         true_size = min(write_buffer_size, WRITE_BUFFER_SIZE);
 744
 745         dev->interrupt_out_buffer =
 746                 kmalloc_array(true_size,
 747                               dev->interrupt_out_endpoint_size,
 748                               GFP_KERNEL);
 749         if (!dev->interrupt_out_buffer)
 750                 goto error;
 751
 752         dev->write_buffer = kmalloc_array(true_size,
 753                                           sizeof(struct alphatrack_ocmd),
 754                                           GFP_KERNEL);
 755         if (!dev->write_buffer)
 756                 goto error;
 757
 758         dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
 759         if (!dev->interrupt_out_urb) {
 760                 dev_err(&intf->dev, "Couldn't allocate interrupt_out_urb\n");
 761                 goto error;
 762         }
 763         dev->interrupt_in_interval =
 764             min_interrupt_in_interval >
 765             dev->interrupt_in_endpoint->
 766             bInterval ? min_interrupt_in_interval : dev->interrupt_in_endpoint->
 767             bInterval;
 768         if (dev->interrupt_out_endpoint)
 769                 dev->interrupt_out_interval =
 770                     min_interrupt_out_interval >
 771                     dev->interrupt_out_endpoint->
 772                     bInterval ? min_interrupt_out_interval : dev->
 773                     interrupt_out_endpoint->bInterval;
 774
 775         /* we can register the device now, as it is ready */
 776         usb_set_intfdata(intf, dev);
 777
 778         atomic_set(&dev->writes_pending, 0);
 779         retval = usb_register_dev(intf, &usb_alphatrack_class);
 780         if (retval) {
 781                 /* something prevented us from registering this driver */
 782                 dev_err(&intf->dev,
 783                         "Not able to get a minor for this device.\n");
 784                 usb_set_intfdata(intf, NULL);
 785                 goto error;
 786         }
 787
 788         /* let the user know what node this device is now attached to */
 789         dev_info(&intf->dev,
 790                  "Alphatrack Device #%d now attached to major %d minor %d\n",
 791                  (intf->minor - USB_ALPHATRACK_MINOR_BASE), USB_MAJOR,
 792                  intf->minor);
 793
 794 exit:
 795         return retval;
 796
 797 error:
 798         usb_alphatrack_delete(dev);
 799
 800         return retval;
 801 }
 802
 803 /**
 804  *      usb_alphatrack_disconnect
 805  *
 806  *      Called by the usb core when the device is removed from the system.
 807  */
 808 static void usb_alphatrack_disconnect(struct usb_interface *intf)
 809 {
 810         struct usb_alphatrack *dev;
 811         int minor;
 812
 813         mutex_lock(&disconnect_mutex);
 814
 815         dev = usb_get_intfdata(intf);
 816         usb_set_intfdata(intf, NULL);
 817
 818         mutex_lock(&dev->mtx);
 819
 820         minor = intf->minor;
 821
 822         /* give back our minor */
 823         usb_deregister_dev(intf, &usb_alphatrack_class);
 824
 825         /* if the device is not opened, then we clean up right now */
 826         if (!dev->open_count) {
 827                 mutex_unlock(&dev->mtx);
 828                 usb_alphatrack_delete(dev);
 829         } else {
 830                 dev->intf = NULL;
 831                 mutex_unlock(&dev->mtx);
 832         }
 833
 834         atomic_set(&dev->writes_pending, 0);
 835         mutex_unlock(&disconnect_mutex);
 836
 837         dev_info(&intf->dev, "Alphatrack Surface #%d now disconnected\n",
 838                  (minor - USB_ALPHATRACK_MINOR_BASE));
 839 }
 840
 841 /* usb specific object needed to register this driver with the usb subsystem */
 842 static struct usb_driver usb_alphatrack_driver = {
 843         .name = "alphatrack",
 844         .probe = usb_alphatrack_probe,
 845         .disconnect = usb_alphatrack_disconnect,
 846         .id_table = usb_alphatrack_table,
 847 };
 848
 849 module_usb_driver(usb_alphatrack_driver);