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