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 const 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 mutex mtx;       /* 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                 unsigned long temp;     \
 202                 if (kstrtoul(buf, 10, &temp))   \
 203                         return -EINVAL; \
 204                 t->value = temp;        \
 205                 return count;   \
 206         }       \
 207         static DEVICE_ATTR(value, S_IWUSR | S_IRUGO, show_##value, set_##value);
 208
 209 show_int(enable);
 210 show_int(offline);
 211 show_set_int(compress_wheel);
 212
 213 /**
 214  *      usb_tranzport_delete
 215  */
 216 static void usb_tranzport_delete(struct usb_tranzport *dev)
 217 {
 218         usb_tranzport_abort_transfers(dev);
 219         if (dev->intf != NULL) {
 220                 device_remove_file(&dev->intf->dev, &dev_attr_enable);
 221                 device_remove_file(&dev->intf->dev, &dev_attr_offline);
 222                 device_remove_file(&dev->intf->dev, &dev_attr_compress_wheel);
 223         }
 224
 225         /* free data structures */
 226         usb_free_urb(dev->interrupt_in_urb);
 227         usb_free_urb(dev->interrupt_out_urb);
 228         kfree(dev->ring_buffer);
 229         kfree(dev->interrupt_in_buffer);
 230         kfree(dev->interrupt_out_buffer);
 231         kfree(dev);
 232 }
 233
 234 /**
 235  *      usb_tranzport_interrupt_in_callback
 236  */
 237
 238 static void usb_tranzport_interrupt_in_callback(struct urb *urb)
 239 {
 240         struct usb_tranzport *dev = urb->context;
 241         unsigned int next_ring_head;
 242         int retval = -1;
 243
 244         if (urb->status) {
 245                 if (urb->status == -ENOENT ||
 246                         urb->status == -ECONNRESET ||
 247                         urb->status == -ESHUTDOWN) {
 248                         goto exit;
 249                 } else {
 250                         dbg_info(&dev->intf->dev,
 251                                  "%s: nonzero status received: %d\n",
 252                                  __func__, urb->status);
 253                         goto resubmit;  /* maybe we can recover */
 254                 }
 255         }
 256
 257         if (urb->actual_length != 8) {
 258                 dev_warn(&dev->intf->dev,
 259                         "Urb length was %d bytes!!"
 260                         "Do something intelligent\n",
 261                          urb->actual_length);
 262         } else {
 263                 dbg_info(&dev->intf->dev,
 264                          "%s: received: %02x%02x%02x%02x%02x%02x%02x%02x\n",
 265                          __func__, dev->interrupt_in_buffer[0],
 266                          dev->interrupt_in_buffer[1],
 267                          dev->interrupt_in_buffer[2],
 268                          dev->interrupt_in_buffer[3],
 269                          dev->interrupt_in_buffer[4],
 270                          dev->interrupt_in_buffer[5],
 271                          dev->interrupt_in_buffer[6],
 272                          dev->interrupt_in_buffer[7]);
 273 #if SUPPRESS_EXTRA_OFFLINE_EVENTS
 274         if (dev->offline == 2 && dev->interrupt_in_buffer[1] == 0xff)
 275                 goto resubmit;
 276                 if (dev->offline == 1 && dev->interrupt_in_buffer[1] == 0xff) {
 277                         dev->offline = 2;
 278                         goto resubmit;
 279                 }
 280
 281                 /* Always pass one offline event up the stack */
 282                 if (dev->offline > 0 && dev->interrupt_in_buffer[1] != 0xff)
 283                         dev->offline = 0;
 284                 if (dev->offline == 0 && dev->interrupt_in_buffer[1] == 0xff)
 285                         dev->offline = 1;
 286
 287 #endif  /* SUPPRESS_EXTRA_OFFLINE_EVENTS */
 288            dbg_info(&dev->intf->dev, "%s: head, tail are %x, %x\n",
 289                 __func__, dev->ring_head, dev->ring_tail);
 290
 291                 next_ring_head = (dev->ring_head + 1) % ring_buffer_size;
 292
 293                 if (next_ring_head != dev->ring_tail) {
 294                         memcpy(&((*dev->ring_buffer)[dev->ring_head]),
 295                                dev->interrupt_in_buffer, urb->actual_length);
 296                         dev->ring_head = next_ring_head;
 297                         retval = 0;
 298                         memset(dev->interrupt_in_buffer, 0, urb->actual_length);
 299                 } else {
 300                         dev_warn(&dev->intf->dev,
 301                                  "Ring buffer overflow, %d bytes dropped\n",
 302                                  urb->actual_length);
 303                         memset(dev->interrupt_in_buffer, 0, urb->actual_length);
 304                 }
 305         }
 306
 307 resubmit:
 308 /* resubmit if we're still running */
 309         if (dev->interrupt_in_running && dev->intf) {
 310                 retval = usb_submit_urb(dev->interrupt_in_urb, GFP_ATOMIC);
 311                 if (retval)
 312                         dev_err(&dev->intf->dev,
 313                                 "usb_submit_urb failed (%d)\n", retval);
 314         }
 315
 316 exit:
 317         dev->interrupt_in_done = 1;
 318         wake_up_interruptible(&dev->read_wait);
 319 }
 320
 321 /**
 322  *      usb_tranzport_interrupt_out_callback
 323  */
 324 static void usb_tranzport_interrupt_out_callback(struct urb *urb)
 325 {
 326         struct usb_tranzport *dev = urb->context;
 327         /* sync/async unlink faults aren't errors */
 328         if (urb->status && !(urb->status == -ENOENT ||
 329                                 urb->status == -ECONNRESET ||
 330                                 urb->status == -ESHUTDOWN))
 331                 dbg_info(&dev->intf->dev,
 332                         "%s - nonzero write interrupt status received: %d\n",
 333                         __func__, urb->status);
 334
 335         dev->interrupt_out_busy = 0;
 336         wake_up_interruptible(&dev->write_wait);
 337 }
 338 /**
 339  *      usb_tranzport_open
 340  */
 341 static int usb_tranzport_open(struct inode *inode, struct file *file)
 342 {
 343         struct usb_tranzport *dev;
 344         int subminor;
 345         int retval = 0;
 346         struct usb_interface *interface;
 347
 348         nonseekable_open(inode, file);
 349         subminor = iminor(inode);
 350
 351         mutex_lock(&disconnect_mutex);
 352
 353         interface = usb_find_interface(&usb_tranzport_driver, subminor);
 354
 355         if (!interface) {
 356                 pr_err("%s - error, can't find device for minor %d\n",
 357                        __func__, subminor);
 358                 retval = -ENODEV;
 359                 goto unlock_disconnect_exit;
 360         }
 361
 362         dev = usb_get_intfdata(interface);
 363
 364         if (!dev) {
 365                 retval = -ENODEV;
 366                 goto unlock_disconnect_exit;
 367         }
 368
 369         /* lock this device */
 370         if (mutex_lock_interruptible(&dev->mtx)) {
 371                 retval = -ERESTARTSYS;
 372                 goto unlock_disconnect_exit;
 373         }
 374
 375         /* allow opening only once */
 376         if (dev->open_count) {
 377                 retval = -EBUSY;
 378                 goto unlock_exit;
 379         }
 380         dev->open_count = 1;
 381
 382         /* initialize in direction */
 383         dev->ring_head = 0;
 384         dev->ring_tail = 0;
 385         usb_fill_int_urb(dev->interrupt_in_urb,
 386                         interface_to_usbdev(interface),
 387                         usb_rcvintpipe(interface_to_usbdev(interface),
 388                                 dev->interrupt_in_endpoint->
 389                                 bEndpointAddress),
 390                         dev->interrupt_in_buffer,
 391                         dev->interrupt_in_endpoint_size,
 392                         usb_tranzport_interrupt_in_callback, dev,
 393                         dev->interrupt_in_interval);
 394
 395         dev->interrupt_in_running = 1;
 396         dev->interrupt_in_done = 0;
 397         dev->enable = 1;
 398         dev->offline = 0;
 399         dev->compress_wheel = 1;
 400
 401         retval = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
 402         if (retval) {
 403                 dev_err(&interface->dev,
 404                         "Couldn't submit interrupt_in_urb %d\n", retval);
 405                 dev->interrupt_in_running = 0;
 406                 dev->open_count = 0;
 407                 goto unlock_exit;
 408         }
 409
 410         /* save device in the file's private structure */
 411         file->private_data = dev;
 412
 413 unlock_exit:
 414         mutex_unlock(&dev->mtx);
 415
 416 unlock_disconnect_exit:
 417         mutex_unlock(&disconnect_mutex);
 418
 419         return retval;
 420 }
 421
 422 /**
 423  *      usb_tranzport_release
 424  */
 425 static int usb_tranzport_release(struct inode *inode, struct file *file)
 426 {
 427         struct usb_tranzport *dev;
 428         int retval = 0;
 429
 430         dev = file->private_data;
 431
 432         if (dev == NULL) {
 433                 retval = -ENODEV;
 434                 goto exit;
 435         }
 436
 437         if (mutex_lock_interruptible(&dev->mtx)) {
 438                 retval = -ERESTARTSYS;
 439                 goto exit;
 440         }
 441
 442         if (dev->open_count != 1) {
 443                 retval = -ENODEV;
 444                 goto unlock_exit;
 445         }
 446
 447         if (dev->intf == NULL) {
 448                 /* the device was unplugged before the file was released */
 449                 mutex_unlock(&dev->mtx);
 450                 /* unlock here as usb_tranzport_delete frees dev */
 451                 usb_tranzport_delete(dev);
 452                 retval = -ENODEV;
 453                 goto exit;
 454         }
 455
 456         /* wait until write transfer is finished */
 457         if (dev->interrupt_out_busy)
 458                 wait_event_interruptible_timeout(dev->write_wait,
 459                                                 !dev->interrupt_out_busy,
 460                                                 2 * HZ);
 461         usb_tranzport_abort_transfers(dev);
 462         dev->open_count = 0;
 463
 464 unlock_exit:
 465         mutex_unlock(&dev->mtx);
 466
 467 exit:
 468         return retval;
 469 }
 470
 471 /**
 472  *      usb_tranzport_poll
 473  */
 474 static unsigned int usb_tranzport_poll(struct file *file, poll_table *wait)
 475 {
 476         struct usb_tranzport *dev;
 477         unsigned int mask = 0;
 478         dev = file->private_data;
 479         poll_wait(file, &dev->read_wait, wait);
 480         poll_wait(file, &dev->write_wait, wait);
 481         if (dev->ring_head != dev->ring_tail)
 482                 mask |= POLLIN | POLLRDNORM;
 483         if (!dev->interrupt_out_busy)
 484                 mask |= POLLOUT | POLLWRNORM;
 485         return mask;
 486 }
 487 /**
 488  *      usb_tranzport_read
 489  */
 490
 491 static ssize_t usb_tranzport_read(struct file *file, char __user *buffer,
 492                                 size_t count, loff_t *ppos)
 493 {
 494         struct usb_tranzport *dev;
 495         int retval = 0;
 496 #if BUFFERED_READS
 497         int c = 0;
 498 #endif
 499 #if COMPRESS_WHEEL_EVENTS
 500         signed char oldwheel;
 501         signed char newwheel;
 502         int cancompress = 1;
 503         int next_tail;
 504 #endif
 505
 506         /* do I have such a thing as a null event? */
 507
 508         dev = file->private_data;
 509
 510         /* verify that we actually have some data to read */
 511         if (count == 0)
 512                 goto exit;
 513
 514         /* lock this object */
 515         if (mutex_lock_interruptible(&dev->mtx)) {
 516                 retval = -ERESTARTSYS;
 517                 goto exit;
 518         }
 519
 520         /* verify that the device wasn't unplugged */
 521         if (dev->intf == NULL) {
 522                 retval = -ENODEV;
 523                 pr_err("%s: No device or device unplugged %d\n",
 524                        __func__, retval);
 525                 goto unlock_exit;
 526         }
 527
 528         while (dev->ring_head == dev->ring_tail) {
 529
 530                 if (file->f_flags & O_NONBLOCK) {
 531                         retval = -EAGAIN;
 532                         goto unlock_exit;
 533                 }
 534                 /* tiny race - FIXME: make atomic? */
 535                 /* atomic_cmp_exchange(&dev->interrupt_in_done,0,0); */
 536                 dev->interrupt_in_done = 0;
 537                 retval = wait_event_interruptible(dev->read_wait,
 538                                                   dev->interrupt_in_done);
 539                 if (retval < 0)
 540                         goto unlock_exit;
 541         }
 542
 543         dbg_info(&dev->intf->dev,
 544                 "%s: copying to userspace: "
 545                 "%02x%02x%02x%02x%02x%02x%02x%02x\n",
 546                  __func__,
 547                  (*dev->ring_buffer)[dev->ring_tail].cmd[0],
 548                  (*dev->ring_buffer)[dev->ring_tail].cmd[1],
 549                  (*dev->ring_buffer)[dev->ring_tail].cmd[2],
 550                  (*dev->ring_buffer)[dev->ring_tail].cmd[3],
 551                  (*dev->ring_buffer)[dev->ring_tail].cmd[4],
 552                  (*dev->ring_buffer)[dev->ring_tail].cmd[5],
 553                  (*dev->ring_buffer)[dev->ring_tail].cmd[6],
 554                  (*dev->ring_buffer)[dev->ring_tail].cmd[7]);
 555
 556 #if BUFFERED_READS
 557         c = 0;
 558         while ((c < count) && (dev->ring_tail != dev->ring_head)) {
 559
 560 #if COMPRESS_WHEEL_EVENTS
 561                 next_tail = (dev->ring_tail+1) % ring_buffer_size;
 562                 if (dev->compress_wheel)
 563                         cancompress = 1;
 564                 while (dev->ring_head != next_tail && cancompress == 1) {
 565                         newwheel = (*dev->ring_buffer)[next_tail].cmd[6];
 566                         oldwheel = (*dev->ring_buffer)[dev->ring_tail].cmd[6];
 567                         /* if both are wheel events, and
 568                            no buttons have changes (FIXME, do I have to check?),
 569                            and we are the same sign, we can compress +- 7F
 570                         */
 571                         dbg_info(&dev->intf->dev,
 572                                 "%s: trying to compress: "
 573                                 "%02x%02x%02x%02x%02x%02x%02x%02x\n",
 574                                 __func__,
 575                                 (*dev->ring_buffer)[dev->ring_tail].cmd[0],
 576                                 (*dev->ring_buffer)[dev->ring_tail].cmd[1],
 577                                 (*dev->ring_buffer)[dev->ring_tail].cmd[2],
 578                                 (*dev->ring_buffer)[dev->ring_tail].cmd[3],
 579                                 (*dev->ring_buffer)[dev->ring_tail].cmd[4],
 580                                 (*dev->ring_buffer)[dev->ring_tail].cmd[5],
 581                                 (*dev->ring_buffer)[dev->ring_tail].cmd[6],
 582                                 (*dev->ring_buffer)[dev->ring_tail].cmd[7]);
 583
 584                         if (((*dev->ring_buffer)[dev->ring_tail].cmd[6] != 0 &&
 585                                 (*dev->ring_buffer)[next_tail].cmd[6] != 0) &&
 586                                 ((newwheel > 0 && oldwheel > 0) ||
 587                                         (newwheel < 0 && oldwheel < 0)) &&
 588                                 ((*dev->ring_buffer)[dev->ring_tail].cmd[2] ==
 589                                 (*dev->ring_buffer)[next_tail].cmd[2]) &&
 590                                 ((*dev->ring_buffer)[dev->ring_tail].cmd[3] ==
 591                                 (*dev->ring_buffer)[next_tail].cmd[3]) &&
 592                                 ((*dev->ring_buffer)[dev->ring_tail].cmd[4] ==
 593                                 (*dev->ring_buffer)[next_tail].cmd[4]) &&
 594                                 ((*dev->ring_buffer)[dev->ring_tail].cmd[5] ==
 595                                 (*dev->ring_buffer)[next_tail].cmd[5])) {
 596                                 dbg_info(&dev->intf->dev,
 597                                         "%s: should compress: "
 598                                         "%02x%02x%02x%02x%02x%02x%02x%02x\n",
 599                                         __func__,
 600                                         (*dev->ring_buffer)[dev->ring_tail].
 601                                         cmd[0],
 602                                         (*dev->ring_buffer)[dev->ring_tail].
 603                                         cmd[1],
 604                                         (*dev->ring_buffer)[dev->ring_tail].
 605                                         cmd[2],
 606                                         (*dev->ring_buffer)[dev->ring_tail].
 607                                         cmd[3],
 608                                         (*dev->ring_buffer)[dev->ring_tail].
 609                                         cmd[4],
 610                                         (*dev->ring_buffer)[dev->ring_tail].
 611                                         cmd[5],
 612                                         (*dev->ring_buffer)[dev->ring_tail].
 613                                         cmd[6],
 614                                         (*dev->ring_buffer)[dev->ring_tail].
 615                                         cmd[7]);
 616                                 newwheel += oldwheel;
 617                                 if (oldwheel > 0 && !(newwheel > 0)) {
 618                                         newwheel = 0x7f;
 619                                         cancompress = 0;
 620                                 }
 621                                 if (oldwheel < 0 && !(newwheel < 0)) {
 622                                         newwheel = 0x80;
 623                                         cancompress = 0;
 624                                 }
 625
 626                                 (*dev->ring_buffer)[next_tail].cmd[6] =
 627                                         newwheel;
 628                                 dev->ring_tail = next_tail;
 629                                 next_tail =
 630                                         (dev->ring_tail + 1) % ring_buffer_size;
 631                         } else {
 632                                 cancompress = 0;
 633                         }
 634                 }
 635 #endif /* COMPRESS_WHEEL_EVENTS */
 636                 if (copy_to_user(
 637                                 &buffer[c],
 638                                 &(*dev->ring_buffer)[dev->ring_tail], 8)) {
 639                         retval = -EFAULT;
 640                         goto unlock_exit;
 641                 }
 642                 dev->ring_tail = (dev->ring_tail + 1) % ring_buffer_size;
 643                 c += 8;
 644                 dbg_info(&dev->intf->dev,
 645                          "%s: head, tail are %x, %x\n",
 646                          __func__, dev->ring_head, dev->ring_tail);
 647         }
 648         retval = c;
 649
 650 #else
 651 /*  if (copy_to_user(buffer, &(*dev->ring_buffer)[dev->ring_tail], 8)) { */
 652         retval = -EFAULT;
 653         goto unlock_exit;
 654 }
 655
 656 dev->ring_tail = (dev->ring_tail + 1) % ring_buffer_size;
 657 dbg_info(&dev->intf->dev, "%s: head, tail are %x, %x\n",
 658          __func__, dev->ring_head, dev->ring_tail);
 659
 660 retval = 8;
 661 #endif /* BUFFERED_READS */
 662
 663 unlock_exit:
 664 /* unlock the device */
 665 mutex_unlock(&dev->mtx);
 666
 667 exit:
 668 return retval;
 669 }
 670
 671 /**
 672  *      usb_tranzport_write
 673  */
 674 static ssize_t usb_tranzport_write(struct file *file,
 675                                 const char __user *buffer, size_t count,
 676                                 loff_t *ppos)
 677 {
 678         struct usb_tranzport *dev;
 679         size_t bytes_to_write;
 680         int retval = 0;
 681
 682         dev = file->private_data;
 683
 684         /* verify that we actually have some data to write */
 685         if (count == 0)
 686                 goto exit;
 687
 688         /* lock this object */
 689         if (mutex_lock_interruptible(&dev->mtx)) {
 690                 retval = -ERESTARTSYS;
 691                 goto exit;
 692         }
 693         /* verify that the device wasn't unplugged */
 694         if (dev->intf == NULL) {
 695                 retval = -ENODEV;
 696                 pr_err("%s: No device or device unplugged %d\n",
 697                        __func__, retval);
 698                 goto unlock_exit;
 699         }
 700
 701         /* wait until previous transfer is finished */
 702         if (dev->interrupt_out_busy) {
 703                 if (file->f_flags & O_NONBLOCK) {
 704                         retval = -EAGAIN;
 705                         goto unlock_exit;
 706                 }
 707                 retval = wait_event_interruptible(dev->write_wait,
 708                                                 !dev->interrupt_out_busy);
 709                 if (retval < 0)
 710                         goto unlock_exit;
 711         }
 712
 713         /* write the data into interrupt_out_buffer from userspace */
 714         bytes_to_write = min(count,
 715                         write_buffer_size *
 716                         dev->interrupt_out_endpoint_size);
 717         if (bytes_to_write < count)
 718                 dev_warn(&dev->intf->dev,
 719                         "Write buffer overflow, %zd bytes dropped\n",
 720                         count - bytes_to_write);
 721
 722         dbg_info(&dev->intf->dev,
 723                 "%s: count = %zd, bytes_to_write = %zd\n", __func__,
 724                 count, bytes_to_write);
 725
 726         if (copy_from_user(dev->interrupt_out_buffer, buffer, bytes_to_write)) {
 727                 retval = -EFAULT;
 728                 goto unlock_exit;
 729         }
 730
 731         if (dev->interrupt_out_endpoint == NULL) {
 732                 dev_err(&dev->intf->dev, "Endpoint should not be be null!\n");
 733                 goto unlock_exit;
 734         }
 735
 736         /* send off the urb */
 737         usb_fill_int_urb(dev->interrupt_out_urb,
 738                         interface_to_usbdev(dev->intf),
 739                         usb_sndintpipe(interface_to_usbdev(dev->intf),
 740                                 dev->interrupt_out_endpoint->
 741                                 bEndpointAddress),
 742                         dev->interrupt_out_buffer, bytes_to_write,
 743                         usb_tranzport_interrupt_out_callback, dev,
 744                         dev->interrupt_out_interval);
 745
 746         dev->interrupt_out_busy = 1;
 747         wmb();
 748
 749         retval = usb_submit_urb(dev->interrupt_out_urb, GFP_KERNEL);
 750         if (retval) {
 751                 dev->interrupt_out_busy = 0;
 752                 dev_err(&dev->intf->dev,
 753                         "Couldn't submit interrupt_out_urb %d\n", retval);
 754                 goto unlock_exit;
 755         }
 756         retval = bytes_to_write;
 757
 758 unlock_exit:
 759         /* unlock the device */
 760         mutex_unlock(&dev->mtx);
 761
 762 exit:
 763         return retval;
 764 }
 765
 766 /* file operations needed when we register this driver */
 767 static const struct file_operations usb_tranzport_fops = {
 768         .owner = THIS_MODULE,
 769         .read = usb_tranzport_read,
 770         .write = usb_tranzport_write,
 771         .open = usb_tranzport_open,
 772         .release = usb_tranzport_release,
 773         .poll = usb_tranzport_poll,
 774         .llseek = no_llseek,
 775 };
 776
 777 /*
 778  * usb class driver info in order to get a minor number from the usb core,
 779  * and to have the device registered with the driver core
 780  */
 781 static struct usb_class_driver usb_tranzport_class = {
 782         .name = "tranzport%d",
 783         .fops = &usb_tranzport_fops,
 784         .minor_base = USB_TRANZPORT_MINOR_BASE,
 785 };
 786
 787 /**
 788  *      usb_tranzport_probe
 789  *
 790  *      Called by the usb core when a new device is connected that it thinks
 791  *      this driver might be interested in.
 792  */
 793 static int usb_tranzport_probe(struct usb_interface *intf,
 794                                const struct usb_device_id *id) {
 795         struct usb_device *udev = interface_to_usbdev(intf);
 796         struct usb_tranzport *dev = NULL;
 797         struct usb_host_interface *iface_desc;
 798         struct usb_endpoint_descriptor *endpoint;
 799         int i;
 800         int true_size;
 801         int retval = -ENOMEM;
 802
 803         /* allocate memory for our device state and initialize it */
 804
 805          dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 806         if (dev == NULL)
 807                 goto exit;
 808
 809         mutex_init(&dev->mtx);
 810         dev->intf = intf;
 811         init_waitqueue_head(&dev->read_wait);
 812         init_waitqueue_head(&dev->write_wait);
 813
 814         iface_desc = intf->cur_altsetting;
 815
 816         /* set up the endpoint information */
 817         for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
 818                 endpoint = &iface_desc->endpoint[i].desc;
 819
 820                 if (usb_endpoint_is_int_in(endpoint))
 821                         dev->interrupt_in_endpoint = endpoint;
 822
 823                 if (usb_endpoint_is_int_out(endpoint))
 824                         dev->interrupt_out_endpoint = endpoint;
 825         }
 826         if (dev->interrupt_in_endpoint == NULL) {
 827                 dev_err(&intf->dev, "Interrupt in endpoint not found\n");
 828                 goto error;
 829         }
 830         if (dev->interrupt_out_endpoint == NULL)
 831                 dev_warn(&intf->dev,
 832                         "Interrupt out endpoint not found"
 833                         "(using control endpoint instead)\n");
 834
 835         dev->interrupt_in_endpoint_size =
 836             le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize);
 837
 838         if (dev->interrupt_in_endpoint_size != 8)
 839                 dev_warn(&intf->dev, "Interrupt in endpoint size is not 8!\n");
 840
 841         if (ring_buffer_size == 0)
 842                 ring_buffer_size = RING_BUFFER_SIZE;
 843         true_size = min(ring_buffer_size, RING_BUFFER_SIZE);
 844
 845         /* FIXME - there are more usb_alloc routines for dma correctness.
 846            Needed? */
 847
 848         dev->ring_buffer =
 849             kmalloc((true_size * sizeof(struct tranzport_cmd)) + 8, GFP_KERNEL);
 850         if (!dev->ring_buffer)
 851                 goto error;
 852
 853         dev->interrupt_in_buffer =
 854             kmalloc(dev->interrupt_in_endpoint_size, GFP_KERNEL);
 855         if (!dev->interrupt_in_buffer)
 856                 goto error;
 857
 858         dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
 859         if (!dev->interrupt_in_urb) {
 860                 dev_err(&intf->dev, "Couldn't allocate interrupt_in_urb\n");
 861                 goto error;
 862         }
 863         dev->interrupt_out_endpoint_size =
 864             dev->interrupt_out_endpoint ?
 865             le16_to_cpu(dev->interrupt_out_endpoint->wMaxPacketSize) :
 866             udev->descriptor.bMaxPacketSize0;
 867
 868         if (dev->interrupt_out_endpoint_size != 8)
 869                 dev_warn(&intf->dev,
 870                          "Interrupt out endpoint size is not 8!)\n");
 871
 872         dev->interrupt_out_buffer =
 873                 kmalloc_array(write_buffer_size,
 874                               dev->interrupt_out_endpoint_size, GFP_KERNEL);
 875         if (!dev->interrupt_out_buffer)
 876                 goto error;
 877
 878         dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
 879         if (!dev->interrupt_out_urb) {
 880                 dev_err(&intf->dev, "Couldn't allocate interrupt_out_urb\n");
 881                 goto error;
 882         }
 883         dev->interrupt_in_interval =
 884             min_interrupt_in_interval >
 885             dev->interrupt_in_endpoint->bInterval ? min_interrupt_in_interval
 886             : dev->interrupt_in_endpoint->bInterval;
 887
 888         if (dev->interrupt_out_endpoint) {
 889                 dev->interrupt_out_interval =
 890                     min_interrupt_out_interval >
 891                     dev->interrupt_out_endpoint->bInterval ?
 892                     min_interrupt_out_interval :
 893                     dev->interrupt_out_endpoint->bInterval;
 894         }
 895
 896         /* we can register the device now, as it is ready */
 897         usb_set_intfdata(intf, dev);
 898
 899         retval = usb_register_dev(intf, &usb_tranzport_class);
 900         if (retval) {
 901                 /* something prevented us from registering this driver */
 902                 dev_err(&intf->dev,
 903                         "Not able to get a minor for this device.\n");
 904                 usb_set_intfdata(intf, NULL);
 905                 goto error;
 906         }
 907
 908         retval = device_create_file(&intf->dev, &dev_attr_compress_wheel);
 909         if (retval)
 910                 goto error;
 911         retval = device_create_file(&intf->dev, &dev_attr_enable);
 912         if (retval)
 913                 goto error;
 914         retval = device_create_file(&intf->dev, &dev_attr_offline);
 915         if (retval)
 916                 goto error;
 917
 918         /* let the user know what node this device is now attached to */
 919         dev_info(&intf->dev,
 920                 "Tranzport Device #%d now attached to major %d minor %d\n",
 921                 (intf->minor - USB_TRANZPORT_MINOR_BASE), USB_MAJOR,
 922                 intf->minor);
 923
 924 exit:
 925         return retval;
 926
 927 error:
 928         usb_tranzport_delete(dev);
 929         return retval;
 930 }
 931
 932 /**
 933  *      usb_tranzport_disconnect
 934  *
 935  *      Called by the usb core when the device is removed from the system.
 936  */
 937 static void usb_tranzport_disconnect(struct usb_interface *intf)
 938 {
 939         struct usb_tranzport *dev;
 940         int minor;
 941         mutex_lock(&disconnect_mutex);
 942         dev = usb_get_intfdata(intf);
 943         usb_set_intfdata(intf, NULL);
 944         mutex_lock(&dev->mtx);
 945         minor = intf->minor;
 946         /* give back our minor */
 947         usb_deregister_dev(intf, &usb_tranzport_class);
 948
 949         /* if the device is not opened, then we clean up right now */
 950         if (!dev->open_count) {
 951                 mutex_unlock(&dev->mtx);
 952                 usb_tranzport_delete(dev);
 953         } else {
 954                 dev->intf = NULL;
 955                 mutex_unlock(&dev->mtx);
 956         }
 957
 958         mutex_unlock(&disconnect_mutex);
 959
 960         dev_info(&intf->dev, "Tranzport Surface #%d now disconnected\n",
 961                 (minor - USB_TRANZPORT_MINOR_BASE));
 962 }
 963
 964 /* usb specific object needed to register this driver with the usb subsystem */
 965 static struct usb_driver usb_tranzport_driver = {
 966         .name = "tranzport",
 967         .probe = usb_tranzport_probe,
 968         .disconnect = usb_tranzport_disconnect,
 969         .id_table = usb_tranzport_table,
 970 };
 971
 972 module_usb_driver(usb_tranzport_driver);