drivers/staging/frontier/tranzport.c

   1 /*
   2  * Frontier Designs Tranzport 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 /* Note: this currently uses a dumb ringbuffer for reads and writes.
  28  * A more optimal driver would cache and kill off outstanding urbs that are
  29  * now invalid, and ignore ones that already were in the queue but valid
  30  * as we only have 17 commands for the tranzport. In particular this is
  31  * key for getting lights to flash in time as otherwise many commands
  32  * can be buffered up before the light change makes it to the interface.
  33  */
  34
  35 #include <linux/kernel.h>
  36 #include <linux/errno.h>
  37 #include <linux/init.h>
  38 #include <linux/slab.h>
  39 #include <linux/module.h>
  40 #include <linux/mutex.h>
  41
  42 #include <linux/uaccess.h>
  43 #include <linux/input.h>
  44 #include <linux/usb.h>
  45 #include <linux/poll.h>
  46
  47 /* Define these values to match your devices */
  48 #define VENDOR_ID   0x165b
  49 #define PRODUCT_ID  0x8101
  50
  51 #ifdef CONFIG_USB_DYNAMIC_MINORS
  52 #define USB_TRANZPORT_MINOR_BASE        0
  53 #else  /* FIXME 177- is the another driver's minor - apply for a minor soon */
  54 #define USB_TRANZPORT_MINOR_BASE        177
  55 #endif
  56
  57 /* table of devices that work with this driver */
  58 static struct usb_device_id usb_tranzport_table[] = {
  59         {USB_DEVICE(VENDOR_ID, PRODUCT_ID)},
  60         {}                      /* Terminating entry */
  61 };
  62
  63 MODULE_DEVICE_TABLE(usb, usb_tranzport_table);
  64 MODULE_VERSION("0.35");
  65 MODULE_AUTHOR("Mike Taht <m@taht.net>");
  66 MODULE_DESCRIPTION("Tranzport USB Driver");
  67 MODULE_LICENSE("GPL");
  68 MODULE_SUPPORTED_DEVICE("Frontier Designs Tranzport Control Surface");
  69
  70 #define SUPPRESS_EXTRA_OFFLINE_EVENTS 1
  71 #define COMPRESS_WHEEL_EVENTS 1
  72 #define BUFFERED_READS 1
  73 #define RING_BUFFER_SIZE 1000
  74 #define WRITE_BUFFER_SIZE 34
  75 #define TRANZPORT_USB_TIMEOUT 10
  76 #define TRANZPORT_DEBUG 0
  77
  78 static int debug = TRANZPORT_DEBUG;
  79
  80 /* Use our own dbg macro */
  81 #define dbg_info(dev, format, arg...) do                        \
  82         { if (debug) dev_info(dev , format , ## arg); } while (0)
  83
  84 /* Module parameters */
  85
  86 module_param(debug, int, S_IRUGO | S_IWUSR);
  87 MODULE_PARM_DESC(debug, "Debug enabled or not");
  88
  89 /* All interrupt in transfers are collected in a ring buffer to
  90  * avoid racing conditions and get better performance of the driver.
  91  */
  92
  93 static int ring_buffer_size = RING_BUFFER_SIZE;
  94
  95 module_param(ring_buffer_size, int, S_IRUGO);
  96 MODULE_PARM_DESC(ring_buffer_size, "Read ring buffer size in reports");
  97
  98 /* The write_buffer can one day contain more than one interrupt out transfer.
  99  */
 100 static int write_buffer_size = WRITE_BUFFER_SIZE;
 101 module_param(write_buffer_size, int, S_IRUGO);
 102 MODULE_PARM_DESC(write_buffer_size, "Write buffer size");
 103
 104 /*
 105  * Increase the interval for debugging purposes.
 106  * or set to 1 to use the standard interval from the endpoint descriptors.
 107  */
 108
 109 static int min_interrupt_in_interval = TRANZPORT_USB_TIMEOUT;
 110 module_param(min_interrupt_in_interval, int, 0);
 111 MODULE_PARM_DESC(min_interrupt_in_interval,
 112                 "Minimum interrupt in interval in ms");
 113
 114 static int min_interrupt_out_interval = TRANZPORT_USB_TIMEOUT;
 115 module_param(min_interrupt_out_interval, int, 0);
 116 MODULE_PARM_DESC(min_interrupt_out_interval,
 117                 "Minimum interrupt out interval in ms");
 118
 119 struct tranzport_cmd {
 120         unsigned char cmd[8];
 121 };
 122
 123 /* Structure to hold all of our device specific stuff */
 124
 125 struct usb_tranzport {
 126         struct semaphore sem;   /* locks this structure */
 127         struct usb_interface *intf;     /* save off the usb interface pointer */
 128         int open_count;         /* number of times this port opened */
 129         struct tranzport_cmd (*ring_buffer)[RING_BUFFER_SIZE];
 130         unsigned int ring_head;
 131         unsigned int ring_tail;
 132         wait_queue_head_t read_wait;
 133         wait_queue_head_t write_wait;
 134         unsigned char *interrupt_in_buffer;
 135         struct usb_endpoint_descriptor *interrupt_in_endpoint;
 136         struct urb *interrupt_in_urb;
 137         int interrupt_in_interval;
 138         size_t interrupt_in_endpoint_size;
 139         int interrupt_in_running;
 140         int interrupt_in_done;
 141         char *interrupt_out_buffer;
 142         struct usb_endpoint_descriptor *interrupt_out_endpoint;
 143         struct urb *interrupt_out_urb;
 144         int interrupt_out_interval;
 145         size_t interrupt_out_endpoint_size;
 146         int interrupt_out_busy;
 147
 148         /* Sysfs support */
 149
 150         unsigned char enable;   /* 0 if disabled 1 if enabled */
 151         unsigned char offline;  /* if the device is out of range or asleep */
 152         unsigned char compress_wheel;   /* flag to compress wheel events */
 153 };
 154
 155 /* prevent races between open() and disconnect() */
 156 static DEFINE_MUTEX(disconnect_mutex);
 157
 158 static struct usb_driver usb_tranzport_driver;
 159
 160 /**
 161  *      usb_tranzport_abort_transfers
 162  *      aborts transfers and frees associated data structures
 163  */
 164 static void usb_tranzport_abort_transfers(struct usb_tranzport *dev)
 165 {
 166         /* shutdown transfer */
 167         if (dev->interrupt_in_running) {
 168                 dev->interrupt_in_running = 0;
 169                 if (dev->intf)
 170                         usb_kill_urb(dev->interrupt_in_urb);
 171         }
 172         if (dev->interrupt_out_busy)
 173                 if (dev->intf)
 174                         usb_kill_urb(dev->interrupt_out_urb);
 175 }
 176
 177 #define show_int(value)                                                 \
 178   static ssize_t show_##value(struct device *dev,                       \
 179                               struct device_attribute *attr, char *buf) \
 180   {                                                                     \
 181     struct usb_interface *intf = to_usb_interface(dev);                 \
 182     struct usb_tranzport *t = usb_get_intfdata(intf);                   \
 183     return sprintf(buf, "%d\n", t->value);                              \
 184   }                                                                     \
 185   static DEVICE_ATTR(value, S_IRUGO, show_##value, NULL);
 186
 187 #define show_set_int(value)                                             \
 188   static ssize_t show_##value(struct device *dev,                       \
 189                               struct device_attribute *attr, char *buf) \
 190   {                                                                     \
 191     struct usb_interface *intf = to_usb_interface(dev);                 \
 192     struct usb_tranzport *t = usb_get_intfdata(intf);                   \
 193     return sprintf(buf, "%d\n", t->value);                              \
 194   }                                                                     \
 195   static ssize_t set_##value(struct device *dev,                        \
 196                              struct device_attribute *attr,             \
 197                              const char *buf, size_t count)             \
 198   {                                                                     \
 199     struct usb_interface *intf = to_usb_interface(dev);                 \
 200     struct usb_tranzport *t = usb_get_intfdata(intf);                   \
 201     int temp = simple_strtoul(buf, NULL, 10);                           \
 202     t->value = temp;                                                    \
 203     return count;                                                       \
 204   }                                                                     \
 205   static DEVICE_ATTR(value, S_IWUSR | S_IRUGO, show_##value, set_##value);
 206
 207 show_int(enable);
 208 show_int(offline);
 209 show_set_int(compress_wheel);
 210
 211 /**
 212  *      usb_tranzport_delete
 213  */
 214 static void usb_tranzport_delete(struct usb_tranzport *dev)
 215 {
 216         usb_tranzport_abort_transfers(dev);
 217         if (dev->intf != NULL) {
 218                 device_remove_file(&dev->intf->dev, &dev_attr_enable);
 219                 device_remove_file(&dev->intf->dev, &dev_attr_offline);
 220                 device_remove_file(&dev->intf->dev, &dev_attr_compress_wheel);
 221         }
 222
 223         /* free data structures */
 224         usb_free_urb(dev->interrupt_in_urb);
 225         usb_free_urb(dev->interrupt_out_urb);
 226         kfree(dev->ring_buffer);
 227         kfree(dev->interrupt_in_buffer);
 228         kfree(dev->interrupt_out_buffer);
 229         kfree(dev);
 230 }
 231
 232 /**
 233  *      usb_tranzport_interrupt_in_callback
 234  */
 235
 236 static void usb_tranzport_interrupt_in_callback(struct urb *urb)
 237 {
 238         struct usb_tranzport *dev = urb->context;
 239         unsigned int next_ring_head;
 240         int retval = -1;
 241
 242         if (urb->status) {
 243                 if (urb->status == -ENOENT ||
 244                         urb->status == -ECONNRESET ||
 245                         urb->status == -ESHUTDOWN) {
 246                         goto exit;
 247                 } else {
 248                         dbg_info(&dev->intf->dev,
 249                                  "%s: nonzero status received: %d\n",
 250                                  __func__, urb->status);
 251                         goto resubmit;  /* maybe we can recover */
 252                 }
 253         }
 254
 255         if (urb->actual_length != 8) {
 256                 dev_warn(&dev->intf->dev,
 257                         "Urb length was %d bytes!!"
 258                         "Do something intelligent \n",
 259                          urb->actual_length);
 260         } else {
 261                 dbg_info(&dev->intf->dev,
 262                          "%s: received: %02x%02x%02x%02x%02x%02x%02x%02x\n",
 263                          __func__, dev->interrupt_in_buffer[0],
 264                          dev->interrupt_in_buffer[1],
 265                          dev->interrupt_in_buffer[2],
 266                          dev->interrupt_in_buffer[3],
 267                          dev->interrupt_in_buffer[4],
 268                          dev->interrupt_in_buffer[5],
 269                          dev->interrupt_in_buffer[6],
 270                          dev->interrupt_in_buffer[7]);
 271 #if SUPPRESS_EXTRA_OFFLINE_EVENTS
 272         if (dev->offline == 2 && dev->interrupt_in_buffer[1] == 0xff)
 273                 goto resubmit;
 274                 if (dev->offline == 1 && dev->interrupt_in_buffer[1] == 0xff) {
 275                         dev->offline = 2;
 276                         goto resubmit;
 277                 }
 278
 279                 /* Always pass one offline event up the stack */
 280                 if (dev->offline > 0 && dev->interrupt_in_buffer[1] != 0xff)
 281                         dev->offline = 0;
 282                 if (dev->offline == 0 && dev->interrupt_in_buffer[1] == 0xff)
 283                         dev->offline = 1;
 284
 285 #endif  /* SUPPRESS_EXTRA_OFFLINE_EVENTS */
 286            dbg_info(&dev->intf->dev, "%s: head, tail are %x, %x\n",
 287                 __func__, dev->ring_head, dev->ring_tail);
 288
 289                 next_ring_head = (dev->ring_head + 1) % ring_buffer_size;
 290
 291                 if (next_ring_head != dev->ring_tail) {
 292                         memcpy(&((*dev->ring_buffer)[dev->ring_head]),
 293                                dev->interrupt_in_buffer, urb->actual_length);
 294                         dev->ring_head = next_ring_head;
 295                         retval = 0;
 296                         memset(dev->interrupt_in_buffer, 0, urb->actual_length);
 297                 } else {
 298                         dev_warn(&dev->intf->dev,
 299                                  "Ring buffer overflow, %d bytes dropped\n",
 300                                  urb->actual_length);
 301                         memset(dev->interrupt_in_buffer, 0, urb->actual_length);
 302                 }
 303         }
 304
 305 resubmit:
 306 /* resubmit if we're still running */
 307         if (dev->interrupt_in_running && dev->intf) {
 308                 retval = usb_submit_urb(dev->interrupt_in_urb, GFP_ATOMIC);
 309                 if (retval)
 310                         dev_err(&dev->intf->dev,
 311                                 "usb_submit_urb failed (%d)\n", retval);
 312         }
 313
 314 exit:
 315         dev->interrupt_in_done = 1;
 316         wake_up_interruptible(&dev->read_wait);
 317 }
 318
 319 /**
 320  *      usb_tranzport_interrupt_out_callback
 321  */
 322 static void usb_tranzport_interrupt_out_callback(struct urb *urb)
 323 {
 324         struct usb_tranzport *dev = urb->context;
 325         /* sync/async unlink faults aren't errors */
 326         if (urb->status && !(urb->status == -ENOENT ||
 327                                 urb->status == -ECONNRESET ||
 328                                 urb->status == -ESHUTDOWN))
 329                 dbg_info(&dev->intf->dev,
 330                         "%s - nonzero write interrupt status received: %d\n",
 331                         __func__, urb->status);
 332
 333         dev->interrupt_out_busy = 0;
 334         wake_up_interruptible(&dev->write_wait);
 335 }
 336 /**
 337  *      usb_tranzport_open
 338  */
 339 static int usb_tranzport_open(struct inode *inode, struct file *file)
 340 {
 341         struct usb_tranzport *dev;
 342         int subminor;
 343         int retval = 0;
 344         struct usb_interface *interface;
 345
 346         nonseekable_open(inode, file);
 347         subminor = iminor(inode);
 348
 349         mutex_lock(&disconnect_mutex);
 350
 351         interface = usb_find_interface(&usb_tranzport_driver, subminor);
 352
 353         if (!interface) {
 354                 err("%s - error, can't find device for minor %d\n",
 355                         __func__, subminor);
 356                 retval = -ENODEV;
 357                 goto unlock_disconnect_exit;
 358         }
 359
 360         dev = usb_get_intfdata(interface);
 361
 362         if (!dev) {
 363                 retval = -ENODEV;
 364                 goto unlock_disconnect_exit;
 365         }
 366
 367         /* lock this device */
 368         if (down_interruptible(&dev->sem)) {
 369                 retval = -ERESTARTSYS;
 370                 goto unlock_disconnect_exit;
 371         }
 372
 373         /* allow opening only once */
 374         if (dev->open_count) {
 375                 retval = -EBUSY;
 376                 goto unlock_exit;
 377         }
 378         dev->open_count = 1;
 379
 380         /* initialize in direction */
 381         dev->ring_head = 0;
 382         dev->ring_tail = 0;
 383         usb_fill_int_urb(dev->interrupt_in_urb,
 384                         interface_to_usbdev(interface),
 385                         usb_rcvintpipe(interface_to_usbdev(interface),
 386                                 dev->interrupt_in_endpoint->
 387                                 bEndpointAddress),
 388                         dev->interrupt_in_buffer,
 389                         dev->interrupt_in_endpoint_size,
 390                         usb_tranzport_interrupt_in_callback, dev,
 391                         dev->interrupt_in_interval);
 392
 393         dev->interrupt_in_running = 1;
 394         dev->interrupt_in_done = 0;
 395         dev->enable = 1;
 396         dev->offline = 0;
 397         dev->compress_wheel = 1;
 398
 399         retval = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
 400         if (retval) {
 401                 dev_err(&interface->dev,
 402                         "Couldn't submit interrupt_in_urb %d\n", retval);
 403                 dev->interrupt_in_running = 0;
 404                 dev->open_count = 0;
 405                 goto unlock_exit;
 406         }
 407
 408         /* save device in the file's private structure */
 409         file->private_data = dev;
 410
 411 unlock_exit:
 412         up(&dev->sem);
 413
 414 unlock_disconnect_exit:
 415         mutex_unlock(&disconnect_mutex);
 416
 417         return retval;
 418 }
 419
 420 /**
 421  *      usb_tranzport_release
 422  */
 423 static int usb_tranzport_release(struct inode *inode, struct file *file)
 424 {
 425         struct usb_tranzport *dev;
 426         int retval = 0;
 427
 428         dev = file->private_data;
 429
 430         if (dev == NULL) {
 431                 retval = -ENODEV;
 432                 goto exit;
 433         }
 434
 435         if (down_interruptible(&dev->sem)) {
 436                 retval = -ERESTARTSYS;
 437                 goto exit;
 438         }
 439
 440         if (dev->open_count != 1) {
 441                 retval = -ENODEV;
 442                 goto unlock_exit;
 443         }
 444
 445         if (dev->intf == NULL) {
 446                 /* the device was unplugged before the file was released */
 447                 up(&dev->sem);
 448                 /* unlock here as usb_tranzport_delete frees dev */
 449                 usb_tranzport_delete(dev);
 450                 retval = -ENODEV;
 451                 goto exit;
 452         }
 453
 454         /* wait until write transfer is finished */
 455         if (dev->interrupt_out_busy)
 456                 wait_event_interruptible_timeout(dev->write_wait,
 457                                                 !dev->interrupt_out_busy,
 458                                                 2 * HZ);
 459         usb_tranzport_abort_transfers(dev);
 460         dev->open_count = 0;
 461
 462 unlock_exit:
 463         up(&dev->sem);
 464
 465 exit:
 466         return retval;
 467 }
 468
 469 /**
 470  *      usb_tranzport_poll
 471  */
 472 static unsigned int usb_tranzport_poll(struct file *file, poll_table * wait)
 473 {
 474         struct usb_tranzport *dev;
 475         unsigned int mask = 0;
 476         dev = file->private_data;
 477         poll_wait(file, &dev->read_wait, wait);
 478         poll_wait(file, &dev->write_wait, wait);
 479         if (dev->ring_head != dev->ring_tail)
 480                 mask |= POLLIN | POLLRDNORM;
 481         if (!dev->interrupt_out_busy)
 482                 mask |= POLLOUT | POLLWRNORM;
 483         return mask;
 484 }
 485 /**
 486  *      usb_tranzport_read
 487  */
 488
 489 static ssize_t usb_tranzport_read(struct file *file, char __user *buffer,
 490                                 size_t count, loff_t *ppos)
 491 {
 492         struct usb_tranzport *dev;
 493         int retval = 0;
 494 #if BUFFERED_READS
 495         int c = 0;
 496 #endif
 497 #if COMPRESS_WHEEL_EVENTS
 498         signed char oldwheel;
 499         signed char newwheel;
 500         int cancompress = 1;
 501         int next_tail;
 502 #endif
 503
 504         /* do I have such a thing as a null event? */
 505
 506         dev = file->private_data;
 507
 508         /* verify that we actually have some data to read */
 509         if (count == 0)
 510                 goto exit;
 511
 512         /* lock this object */
 513         if (down_interruptible(&dev->sem)) {
 514                 retval = -ERESTARTSYS;
 515                 goto exit;
 516         }
 517
 518         /* verify that the device wasn't unplugged */ if (dev->intf == NULL) {
 519                 retval = -ENODEV;
 520                 err("No device or device unplugged %d\n", retval);
 521                 goto unlock_exit;
 522         }
 523
 524         while (dev->ring_head == dev->ring_tail) {
 525
 526                 if (file->f_flags & O_NONBLOCK) {
 527                         retval = -EAGAIN;
 528                         goto unlock_exit;
 529                 }
 530                 /* tiny race - FIXME: make atomic? */
 531                 /* atomic_cmp_exchange(&dev->interrupt_in_done,0,0); */
 532                 dev->interrupt_in_done = 0;
 533                 retval = wait_event_interruptible(dev->read_wait,
 534                                                   dev->interrupt_in_done);
 535                 if (retval < 0)
 536                         goto unlock_exit;
 537         }
 538
 539         dbg_info(&dev->intf->dev,
 540                 "%s: copying to userspace: "
 541                 "%02x%02x%02x%02x%02x%02x%02x%02x\n",
 542                  __func__,
 543                  (*dev->ring_buffer)[dev->ring_tail].cmd[0],
 544                  (*dev->ring_buffer)[dev->ring_tail].cmd[1],
 545                  (*dev->ring_buffer)[dev->ring_tail].cmd[2],
 546                  (*dev->ring_buffer)[dev->ring_tail].cmd[3],
 547                  (*dev->ring_buffer)[dev->ring_tail].cmd[4],
 548                  (*dev->ring_buffer)[dev->ring_tail].cmd[5],
 549                  (*dev->ring_buffer)[dev->ring_tail].cmd[6],
 550                  (*dev->ring_buffer)[dev->ring_tail].cmd[7]);
 551
 552 #if BUFFERED_READS
 553         c = 0;
 554         while ((c < count) && (dev->ring_tail != dev->ring_head)) {
 555
 556 #if COMPRESS_WHEEL_EVENTS
 557                 next_tail = (dev->ring_tail+1) % ring_buffer_size;
 558                 if (dev->compress_wheel)
 559                         cancompress = 1;
 560                 while (dev->ring_head != next_tail && cancompress == 1) {
 561                         newwheel = (*dev->ring_buffer)[next_tail].cmd[6];
 562                         oldwheel = (*dev->ring_buffer)[dev->ring_tail].cmd[6];
 563                         /* if both are wheel events, and
 564                            no buttons have changes (FIXME, do I have to check?),
 565                            and we are the same sign, we can compress +- 7F
 566                         */
 567                         dbg_info(&dev->intf->dev,
 568                                 "%s: trying to compress: "
 569                                 "%02x%02x%02x%02x%02x%02x%02x%02x\n",
 570                                 __func__,
 571                                 (*dev->ring_buffer)[dev->ring_tail].cmd[0],
 572                                 (*dev->ring_buffer)[dev->ring_tail].cmd[1],
 573                                 (*dev->ring_buffer)[dev->ring_tail].cmd[2],
 574                                 (*dev->ring_buffer)[dev->ring_tail].cmd[3],
 575                                 (*dev->ring_buffer)[dev->ring_tail].cmd[4],
 576                                 (*dev->ring_buffer)[dev->ring_tail].cmd[5],
 577                                 (*dev->ring_buffer)[dev->ring_tail].cmd[6],
 578                                 (*dev->ring_buffer)[dev->ring_tail].cmd[7]);
 579
 580                         if (((*dev->ring_buffer)[dev->ring_tail].cmd[6] != 0 &&
 581                                 (*dev->ring_buffer)[next_tail].cmd[6] != 0) &&
 582                                 ((newwheel > 0 && oldwheel > 0) ||
 583                                         (newwheel < 0 && oldwheel < 0)) &&
 584                                 ((*dev->ring_buffer)[dev->ring_tail].cmd[2] ==
 585                                 (*dev->ring_buffer)[next_tail].cmd[2]) &&
 586                                 ((*dev->ring_buffer)[dev->ring_tail].cmd[3] ==
 587                                 (*dev->ring_buffer)[next_tail].cmd[3]) &&
 588                                 ((*dev->ring_buffer)[dev->ring_tail].cmd[4] ==
 589                                 (*dev->ring_buffer)[next_tail].cmd[4]) &&
 590                                 ((*dev->ring_buffer)[dev->ring_tail].cmd[5] ==
 591                                 (*dev->ring_buffer)[next_tail].cmd[5])) {
 592                                 dbg_info(&dev->intf->dev,
 593                                         "%s: should compress: "
 594                                         "%02x%02x%02x%02x%02x%02x%02x%02x\n",
 595                                         __func__,
 596                                         (*dev->ring_buffer)[dev->ring_tail].
 597                                         cmd[0],
 598                                         (*dev->ring_buffer)[dev->ring_tail].
 599                                         cmd[1],
 600                                         (*dev->ring_buffer)[dev->ring_tail].
 601                                         cmd[2],
 602                                         (*dev->ring_buffer)[dev->ring_tail].
 603                                         cmd[3],
 604                                         (*dev->ring_buffer)[dev->ring_tail].
 605                                         cmd[4],
 606                                         (*dev->ring_buffer)[dev->ring_tail].
 607                                         cmd[5],
 608                                         (*dev->ring_buffer)[dev->ring_tail].
 609                                         cmd[6],
 610                                         (*dev->ring_buffer)[dev->ring_tail].
 611                                         cmd[7]);
 612                                 newwheel += oldwheel;
 613                                 if (oldwheel > 0 && !(newwheel > 0)) {
 614                                         newwheel = 0x7f;
 615                                         cancompress = 0;
 616                                 }
 617                                 if (oldwheel < 0 && !(newwheel < 0)) {
 618                                         newwheel = 0x80;
 619                                         cancompress = 0;
 620                                 }
 621
 622                                 (*dev->ring_buffer)[next_tail].cmd[6] =
 623                                         newwheel;
 624                                 dev->ring_tail = next_tail;
 625                                 next_tail =
 626                                         (dev->ring_tail + 1) % ring_buffer_size;
 627                         } else {
 628                                 cancompress = 0;
 629                         }
 630                 }
 631 #endif /* COMPRESS_WHEEL_EVENTS */
 632                 if (copy_to_user(
 633                                 &buffer[c],
 634                                 &(*dev->ring_buffer)[dev->ring_tail], 8)) {
 635                         retval = -EFAULT;
 636                         goto unlock_exit;
 637                 }
 638                 dev->ring_tail = (dev->ring_tail + 1) % ring_buffer_size;
 639                 c += 8;
 640                 dbg_info(&dev->intf->dev,
 641                          "%s: head, tail are %x, %x\n",
 642                          __func__, dev->ring_head, dev->ring_tail);
 643         }
 644         retval = c;
 645
 646 #else
 647 /*  if (copy_to_user(buffer, &(*dev->ring_buffer)[dev->ring_tail], 8)) { */
 648         retval = -EFAULT;
 649         goto unlock_exit;
 650 }
 651
 652 dev->ring_tail = (dev->ring_tail + 1) % ring_buffer_size;
 653 dbg_info(&dev->intf->dev, "%s: head, tail are %x, %x\n",
 654          __func__, dev->ring_head, dev->ring_tail);
 655
 656 retval = 8;
 657 #endif /* BUFFERED_READS */
 658
 659 unlock_exit:
 660 /* unlock the device */
 661 up(&dev->sem);
 662
 663 exit:
 664 return retval;
 665 }
 666
 667 /**
 668  *      usb_tranzport_write
 669  */
 670 static ssize_t usb_tranzport_write(struct file *file,
 671                                 const char __user *buffer, size_t count,
 672                                 loff_t *ppos)
 673 {
 674         struct usb_tranzport *dev;
 675         size_t bytes_to_write;
 676         int retval = 0;
 677
 678         dev = file->private_data;
 679
 680         /* verify that we actually have some data to write */
 681         if (count == 0)
 682                 goto exit;
 683
 684         /* lock this object */
 685         if (down_interruptible(&dev->sem)) {
 686                 retval = -ERESTARTSYS;
 687                 goto exit;
 688         }
 689         /* verify that the device wasn't unplugged */
 690         if (dev->intf == NULL) {
 691                 retval = -ENODEV;
 692                 err("No device or device unplugged %d\n", retval);
 693                 goto unlock_exit;
 694         }
 695
 696         /* wait until previous transfer is finished */
 697         if (dev->interrupt_out_busy) {
 698                 if (file->f_flags & O_NONBLOCK) {
 699                         retval = -EAGAIN;
 700                         goto unlock_exit;
 701                 }
 702                 retval = wait_event_interruptible(dev->write_wait,
 703                                                 !dev->interrupt_out_busy);
 704                 if (retval < 0)
 705                         goto unlock_exit;
 706         }
 707
 708         /* write the data into interrupt_out_buffer from userspace */
 709         bytes_to_write = min(count,
 710                         write_buffer_size *
 711                         dev->interrupt_out_endpoint_size);
 712         if (bytes_to_write < count)
 713                 dev_warn(&dev->intf->dev,
 714                         "Write buffer overflow, %zd bytes dropped\n",
 715                         count - bytes_to_write);
 716
 717         dbg_info(&dev->intf->dev,
 718                 "%s: count = %zd, bytes_to_write = %zd\n", __func__,
 719                 count, bytes_to_write);
 720
 721         if (copy_from_user(dev->interrupt_out_buffer, buffer, bytes_to_write)) {
 722                 retval = -EFAULT;
 723                 goto unlock_exit;
 724         }
 725
 726         if (dev->interrupt_out_endpoint == NULL) {
 727                 err("Endpoint should not be be null! \n");
 728                 goto unlock_exit;
 729         }
 730
 731         /* send off the urb */
 732         usb_fill_int_urb(dev->interrupt_out_urb,
 733                         interface_to_usbdev(dev->intf),
 734                         usb_sndintpipe(interface_to_usbdev(dev->intf),
 735                                 dev->interrupt_out_endpoint->
 736                                 bEndpointAddress),
 737                         dev->interrupt_out_buffer, bytes_to_write,
 738                         usb_tranzport_interrupt_out_callback, dev,
 739                         dev->interrupt_out_interval);
 740
 741         dev->interrupt_out_busy = 1;
 742         wmb();
 743
 744         retval = usb_submit_urb(dev->interrupt_out_urb, GFP_KERNEL);
 745         if (retval) {
 746                 dev->interrupt_out_busy = 0;
 747                 err("Couldn't submit interrupt_out_urb %d\n", retval);
 748                 goto unlock_exit;
 749         }
 750         retval = bytes_to_write;
 751
 752 unlock_exit:
 753         /* unlock the device */
 754         up(&dev->sem);
 755
 756 exit:
 757         return retval;
 758 }
 759
 760 /* file operations needed when we register this driver */
 761 static const struct file_operations usb_tranzport_fops = {
 762         .owner = THIS_MODULE,
 763         .read = usb_tranzport_read,
 764         .write = usb_tranzport_write,
 765         .open = usb_tranzport_open,
 766         .release = usb_tranzport_release,
 767         .poll = usb_tranzport_poll,
 768 };
 769
 770 /*
 771  * usb class driver info in order to get a minor number from the usb core,
 772  * and to have the device registered with the driver core
 773  */
 774 static struct usb_class_driver usb_tranzport_class = {
 775         .name = "tranzport%d",
 776         .fops = &usb_tranzport_fops,
 777         .minor_base = USB_TRANZPORT_MINOR_BASE,
 778 };
 779
 780 /**
 781  *      usb_tranzport_probe
 782  *
 783  *      Called by the usb core when a new device is connected that it thinks
 784  *      this driver might be interested in.
 785  */
 786 static int usb_tranzport_probe(struct usb_interface *intf,
 787                                const struct usb_device_id *id) {
 788         struct usb_device *udev = interface_to_usbdev(intf);
 789         struct usb_tranzport *dev = NULL;
 790         struct usb_host_interface *iface_desc;
 791         struct usb_endpoint_descriptor *endpoint;
 792         int i;
 793         int true_size;
 794         int retval = -ENOMEM;
 795
 796         /* allocate memory for our device state and intialize it */
 797
 798          dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 799         if (dev == NULL) {
 800                 dev_err(&intf->dev, "Out of memory\n");
 801                 goto exit;
 802         }
 803         init_MUTEX(&dev->sem);
 804         dev->intf = intf;
 805         init_waitqueue_head(&dev->read_wait);
 806         init_waitqueue_head(&dev->write_wait);
 807
 808         iface_desc = intf->cur_altsetting;
 809
 810         /* set up the endpoint information */
 811         for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
 812                 endpoint = &iface_desc->endpoint[i].desc;
 813
 814                 if (usb_endpoint_is_int_in(endpoint))
 815                         dev->interrupt_in_endpoint = endpoint;
 816
 817                 if (usb_endpoint_is_int_out(endpoint))
 818                         dev->interrupt_out_endpoint = endpoint;
 819         }
 820         if (dev->interrupt_in_endpoint == NULL) {
 821                 dev_err(&intf->dev, "Interrupt in endpoint not found\n");
 822                 goto error;
 823         }
 824         if (dev->interrupt_out_endpoint == NULL)
 825                 dev_warn(&intf->dev,
 826                         "Interrupt out endpoint not found"
 827                         "(using control endpoint instead)\n");
 828
 829         dev->interrupt_in_endpoint_size =
 830             le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize);
 831
 832         if (dev->interrupt_in_endpoint_size != 8)
 833                 dev_warn(&intf->dev, "Interrupt in endpoint size is not 8!\n");
 834
 835         if (ring_buffer_size == 0)
 836                 ring_buffer_size = RING_BUFFER_SIZE;
 837         true_size = min(ring_buffer_size, RING_BUFFER_SIZE);
 838
 839         /* FIXME - there are more usb_alloc routines for dma correctness.
 840            Needed? */
 841
 842         dev->ring_buffer =
 843             kmalloc((true_size * sizeof(struct tranzport_cmd)) + 8, GFP_KERNEL);
 844
 845         if (!dev->ring_buffer) {
 846                 dev_err(&intf->dev,
 847                         "Couldn't allocate ring_buffer size %d\n", true_size);
 848                 goto error;
 849         }
 850         dev->interrupt_in_buffer =
 851             kmalloc(dev->interrupt_in_endpoint_size, GFP_KERNEL);
 852         if (!dev->interrupt_in_buffer) {
 853                 dev_err(&intf->dev, "Couldn't allocate interrupt_in_buffer\n");
 854                 goto error;
 855         }
 856         dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
 857         if (!dev->interrupt_in_urb) {
 858                 dev_err(&intf->dev, "Couldn't allocate interrupt_in_urb\n");
 859                 goto error;
 860         }
 861         dev->interrupt_out_endpoint_size =
 862             dev->interrupt_out_endpoint ?
 863             le16_to_cpu(dev->interrupt_out_endpoint->wMaxPacketSize) :
 864             udev->descriptor.bMaxPacketSize0;
 865
 866         if (dev->interrupt_out_endpoint_size != 8)
 867                 dev_warn(&intf->dev,
 868                          "Interrupt out endpoint size is not 8!)\n");
 869
 870         dev->interrupt_out_buffer =
 871             kmalloc(write_buffer_size * dev->interrupt_out_endpoint_size,
 872                     GFP_KERNEL);
 873         if (!dev->interrupt_out_buffer) {
 874                 dev_err(&intf->dev, "Couldn't allocate interrupt_out_buffer\n");
 875                 goto error;
 876         }
 877         dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
 878         if (!dev->interrupt_out_urb) {
 879                 dev_err(&intf->dev, "Couldn't allocate interrupt_out_urb\n");
 880                 goto error;
 881         }
 882         dev->interrupt_in_interval =
 883             min_interrupt_in_interval >
 884             dev->interrupt_in_endpoint->bInterval ? min_interrupt_in_interval
 885             : dev->interrupt_in_endpoint->bInterval;
 886
 887         if (dev->interrupt_out_endpoint) {
 888                 dev->interrupt_out_interval =
 889                     min_interrupt_out_interval >
 890                     dev->interrupt_out_endpoint->bInterval ?
 891                     min_interrupt_out_interval :
 892                     dev->interrupt_out_endpoint->bInterval;
 893         }
 894
 895         /* we can register the device now, as it is ready */
 896         usb_set_intfdata(intf, dev);
 897
 898         retval = usb_register_dev(intf, &usb_tranzport_class);
 899         if (retval) {
 900                 /* something prevented us from registering this driver */
 901                 dev_err(&intf->dev,
 902                         "Not able to get a minor for this device.\n");
 903                 usb_set_intfdata(intf, NULL);
 904                 goto error;
 905         }
 906
 907         retval = device_create_file(&intf->dev, &dev_attr_compress_wheel);
 908         if (retval)
 909                 goto error;
 910         retval = device_create_file(&intf->dev, &dev_attr_enable);
 911         if (retval)
 912                 goto error;
 913         retval = device_create_file(&intf->dev, &dev_attr_offline);
 914         if (retval)
 915                 goto error;
 916
 917         /* let the user know what node this device is now attached to */
 918         dev_info(&intf->dev,
 919                 "Tranzport Device #%d now attached to major %d minor %d\n",
 920                 (intf->minor - USB_TRANZPORT_MINOR_BASE), USB_MAJOR,
 921                 intf->minor);
 922
 923 exit:
 924         return retval;
 925
 926 error:
 927         usb_tranzport_delete(dev);
 928         return retval;
 929 }
 930
 931 /**
 932  *      usb_tranzport_disconnect
 933  *
 934  *      Called by the usb core when the device is removed from the system.
 935  */
 936 static void usb_tranzport_disconnect(struct usb_interface *intf)
 937 {
 938         struct usb_tranzport *dev;
 939         int minor;
 940         mutex_lock(&disconnect_mutex);
 941         dev = usb_get_intfdata(intf);
 942         usb_set_intfdata(intf, NULL);
 943         down(&dev->sem);
 944         minor = intf->minor;
 945         /* give back our minor */
 946         usb_deregister_dev(intf, &usb_tranzport_class);
 947
 948         /* if the device is not opened, then we clean up right now */
 949         if (!dev->open_count) {
 950                 up(&dev->sem);
 951                 usb_tranzport_delete(dev);
 952         } else {
 953                 dev->intf = NULL;
 954                 up(&dev->sem);
 955         }
 956
 957         mutex_unlock(&disconnect_mutex);
 958
 959         dev_info(&intf->dev, "Tranzport Surface #%d now disconnected\n",
 960                 (minor - USB_TRANZPORT_MINOR_BASE));
 961 }
 962
 963 /* usb specific object needed to register this driver with the usb subsystem */
 964 static struct usb_driver usb_tranzport_driver = {
 965         .name = "tranzport",
 966         .probe = usb_tranzport_probe,
 967         .disconnect = usb_tranzport_disconnect,
 968         .id_table = usb_tranzport_table,
 969 };
 970
 971 /**
 972  *      usb_tranzport_init
 973  */
 974 static int __init usb_tranzport_init(void)
 975 {
 976         int retval;
 977
 978         /* register this driver with the USB subsystem */
 979         retval = usb_register(&usb_tranzport_driver);
 980         if (retval)
 981                 err("usb_register failed for the " __FILE__
 982                         " driver. Error number %d\n", retval);
 983         return retval;
 984 }
 985 /**
 986  *      usb_tranzport_exit
 987  */
 988
 989 static void __exit usb_tranzport_exit(void)
 990 {
 991         /* deregister this driver with the USB subsystem */
 992         usb_deregister(&usb_tranzport_driver);
 993 }
 994
 995 module_init(usb_tranzport_init);
 996 module_exit(usb_tranzport_exit);