drivers/usb/misc/legousbtower.c

   1 /*
   2  * LEGO USB Tower driver
   3  *
   4  * Copyright (C) 2003 David Glance <davidgsf@sourceforge.net>
   5  *               2001-2004 Juergen Stuber <starblue@users.sourceforge.net>
   6  *
   7  *      This program is free software; you can redistribute it and/or
   8  *      modify it under the terms of the GNU General Public License as
   9  *      published by the Free Software Foundation; either version 2 of
  10  *      the License, or (at your option) any later version.
  11  *
  12  * derived from USB Skeleton driver - 0.5
  13  * Copyright (C) 2001 Greg Kroah-Hartman (greg@kroah.com)
  14  *
  15  * History:
  16  *
  17  * 2001-10-13 - 0.1 js
  18  *   - first version
  19  * 2001-11-03 - 0.2 js
  20  *   - simplified buffering, one-shot URBs for writing
  21  * 2001-11-10 - 0.3 js
  22  *   - removed IOCTL (setting power/mode is more complicated, postponed)
  23  * 2001-11-28 - 0.4 js
  24  *   - added vendor commands for mode of operation and power level in open
  25  * 2001-12-04 - 0.5 js
  26  *   - set IR mode by default (by oversight 0.4 set VLL mode)
  27  * 2002-01-11 - 0.5? pcchan
  28  *   - make read buffer reusable and work around bytes_to_write issue between
  29  *     uhci and legusbtower
  30  * 2002-09-23 - 0.52 david (david@csse.uwa.edu.au)
  31  *   - imported into lejos project
  32  *   - changed wake_up to wake_up_interruptible
  33  *   - changed to use lego0 rather than tower0
  34  *   - changed dbg() to use __func__ rather than deprecated __func__
  35  * 2003-01-12 - 0.53 david (david@csse.uwa.edu.au)
  36  *   - changed read and write to write everything or
  37  *     timeout (from a patch by Chris Riesen and Brett Thaeler driver)
  38  *   - added ioctl functionality to set timeouts
  39  * 2003-07-18 - 0.54 davidgsf (david@csse.uwa.edu.au)
  40  *   - initial import into LegoUSB project
  41  *   - merge of existing LegoUSB.c driver
  42  * 2003-07-18 - 0.56 davidgsf (david@csse.uwa.edu.au)
  43  *   - port to 2.6 style driver
  44  * 2004-02-29 - 0.6 Juergen Stuber <starblue@users.sourceforge.net>
  45  *   - fix locking
  46  *   - unlink read URBs which are no longer needed
  47  *   - allow increased buffer size, eliminates need for timeout on write
  48  *   - have read URB running continuously
  49  *   - added poll
  50  *   - forbid seeking
  51  *   - added nonblocking I/O
  52  *   - changed back __func__ to __func__
  53  *   - read and log tower firmware version
  54  *   - reset tower on probe, avoids failure of first write
  55  * 2004-03-09 - 0.7 Juergen Stuber <starblue@users.sourceforge.net>
  56  *   - timeout read now only after inactivity, shorten default accordingly
  57  * 2004-03-11 - 0.8 Juergen Stuber <starblue@users.sourceforge.net>
  58  *   - log major, minor instead of possibly confusing device filename
  59  *   - whitespace cleanup
  60  * 2004-03-12 - 0.9 Juergen Stuber <starblue@users.sourceforge.net>
  61  *   - normalize whitespace in debug messages
  62  *   - take care about endianness in control message responses
  63  * 2004-03-13 - 0.91 Juergen Stuber <starblue@users.sourceforge.net>
  64  *   - make default intervals longer to accommodate current EHCI driver
  65  * 2004-03-19 - 0.92 Juergen Stuber <starblue@users.sourceforge.net>
  66  *   - replaced atomic_t by memory barriers
  67  * 2004-04-21 - 0.93 Juergen Stuber <starblue@users.sourceforge.net>
  68  *   - wait for completion of write urb in release (needed for remotecontrol)
  69  *   - corrected poll for write direction (missing negation)
  70  * 2004-04-22 - 0.94 Juergen Stuber <starblue@users.sourceforge.net>
  71  *   - make device locking interruptible
  72  * 2004-04-30 - 0.95 Juergen Stuber <starblue@users.sourceforge.net>
  73  *   - check for valid udev on resubmitting and unlinking urbs
  74  * 2004-08-03 - 0.96 Juergen Stuber <starblue@users.sourceforge.net>
  75  *   - move reset into open to clean out spurious data
  76  */
  77
  78 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  79
  80 #include <linux/kernel.h>
  81 #include <linux/errno.h>
  82 #include <linux/slab.h>
  83 #include <linux/module.h>
  84 #include <linux/completion.h>
  85 #include <linux/mutex.h>
  86 #include <asm/uaccess.h>
  87 #include <linux/usb.h>
  88 #include <linux/poll.h>
  89
  90
  91 /* Version Information */
  92 #define DRIVER_VERSION "v0.96"
  93 #define DRIVER_AUTHOR "Juergen Stuber <starblue@sourceforge.net>"
  94 #define DRIVER_DESC "LEGO USB Tower Driver"
  95
  96
  97 /* The defaults are chosen to work with the latest versions of leJOS and NQC.
  98  */
  99
 100 /* Some legacy software likes to receive packets in one piece.
 101  * In this case read_buffer_size should exceed the maximal packet length
 102  * (417 for datalog uploads), and packet_timeout should be set.
 103  */
 104 static int read_buffer_size = 480;
 105 module_param(read_buffer_size, int, 0);
 106 MODULE_PARM_DESC(read_buffer_size, "Read buffer size");
 107
 108 /* Some legacy software likes to send packets in one piece.
 109  * In this case write_buffer_size should exceed the maximal packet length
 110  * (417 for firmware and program downloads).
 111  * A problem with long writes is that the following read may time out
 112  * if the software is not prepared to wait long enough.
 113  */
 114 static int write_buffer_size = 480;
 115 module_param(write_buffer_size, int, 0);
 116 MODULE_PARM_DESC(write_buffer_size, "Write buffer size");
 117
 118 /* Some legacy software expects reads to contain whole LASM packets.
 119  * To achieve this, characters which arrive before a packet timeout
 120  * occurs will be returned in a single read operation.
 121  * A problem with long reads is that the software may time out
 122  * if it is not prepared to wait long enough.
 123  * The packet timeout should be greater than the time between the
 124  * reception of subsequent characters, which should arrive about
 125  * every 5ms for the standard 2400 baud.
 126  * Set it to 0 to disable.
 127  */
 128 static int packet_timeout = 50;
 129 module_param(packet_timeout, int, 0);
 130 MODULE_PARM_DESC(packet_timeout, "Packet timeout in ms");
 131
 132 /* Some legacy software expects blocking reads to time out.
 133  * Timeout occurs after the specified time of read and write inactivity.
 134  * Set it to 0 to disable.
 135  */
 136 static int read_timeout = 200;
 137 module_param(read_timeout, int, 0);
 138 MODULE_PARM_DESC(read_timeout, "Read timeout in ms");
 139
 140 /* As of kernel version 2.6.4 ehci-hcd uses an
 141  * "only one interrupt transfer per frame" shortcut
 142  * to simplify the scheduling of periodic transfers.
 143  * This conflicts with our standard 1ms intervals for in and out URBs.
 144  * We use default intervals of 2ms for in and 8ms for out transfers,
 145  * which is fast enough for 2400 baud and allows a small additional load.
 146  * Increase the interval to allow more devices that do interrupt transfers,
 147  * or set to 0 to use the standard interval from the endpoint descriptors.
 148  */
 149 static int interrupt_in_interval = 2;
 150 module_param(interrupt_in_interval, int, 0);
 151 MODULE_PARM_DESC(interrupt_in_interval, "Interrupt in interval in ms");
 152
 153 static int interrupt_out_interval = 8;
 154 module_param(interrupt_out_interval, int, 0);
 155 MODULE_PARM_DESC(interrupt_out_interval, "Interrupt out interval in ms");
 156
 157 /* Define these values to match your device */
 158 #define LEGO_USB_TOWER_VENDOR_ID        0x0694
 159 #define LEGO_USB_TOWER_PRODUCT_ID       0x0001
 160
 161 /* Vendor requests */
 162 #define LEGO_USB_TOWER_REQUEST_RESET            0x04
 163 #define LEGO_USB_TOWER_REQUEST_GET_VERSION      0xFD
 164
 165 struct tower_reset_reply {
 166         __le16 size;            /* little-endian */
 167         __u8 err_code;
 168         __u8 spare;
 169 } __attribute__ ((packed));
 170
 171 struct tower_get_version_reply {
 172         __le16 size;            /* little-endian */
 173         __u8 err_code;
 174         __u8 spare;
 175         __u8 major;
 176         __u8 minor;
 177         __le16 build_no;                /* little-endian */
 178 } __attribute__ ((packed));
 179
 180
 181 /* table of devices that work with this driver */
 182 static const struct usb_device_id tower_table[] = {
 183         { USB_DEVICE(LEGO_USB_TOWER_VENDOR_ID, LEGO_USB_TOWER_PRODUCT_ID) },
 184         { }                                     /* Terminating entry */
 185 };
 186
 187 MODULE_DEVICE_TABLE (usb, tower_table);
 188 static DEFINE_MUTEX(open_disc_mutex);
 189
 190 #define LEGO_USB_TOWER_MINOR_BASE       160
 191
 192
 193 /* Structure to hold all of our device specific stuff */
 194 struct lego_usb_tower {
 195         struct mutex            lock;           /* locks this structure */
 196         struct usb_device*      udev;           /* save off the usb device pointer */
 197         unsigned char           minor;          /* the starting minor number for this device */
 198
 199         int                     open_count;     /* number of times this port has been opened */
 200
 201         char*                   read_buffer;
 202         size_t                  read_buffer_length; /* this much came in */
 203         size_t                  read_packet_length; /* this much will be returned on read */
 204         spinlock_t              read_buffer_lock;
 205         int                     packet_timeout_jiffies;
 206         unsigned long           read_last_arrival;
 207
 208         wait_queue_head_t       read_wait;
 209         wait_queue_head_t       write_wait;
 210
 211         char*                   interrupt_in_buffer;
 212         struct usb_endpoint_descriptor* interrupt_in_endpoint;
 213         struct urb*             interrupt_in_urb;
 214         int                     interrupt_in_interval;
 215         int                     interrupt_in_running;
 216         int                     interrupt_in_done;
 217
 218         char*                   interrupt_out_buffer;
 219         struct usb_endpoint_descriptor* interrupt_out_endpoint;
 220         struct urb*             interrupt_out_urb;
 221         int                     interrupt_out_interval;
 222         int                     interrupt_out_busy;
 223
 224 };
 225
 226
 227 /* local function prototypes */
 228 static ssize_t tower_read       (struct file *file, char __user *buffer, size_t count, loff_t *ppos);
 229 static ssize_t tower_write      (struct file *file, const char __user *buffer, size_t count, loff_t *ppos);
 230 static inline void tower_delete (struct lego_usb_tower *dev);
 231 static int tower_open           (struct inode *inode, struct file *file);
 232 static int tower_release        (struct inode *inode, struct file *file);
 233 static unsigned int tower_poll  (struct file *file, poll_table *wait);
 234 static loff_t tower_llseek      (struct file *file, loff_t off, int whence);
 235
 236 static void tower_abort_transfers (struct lego_usb_tower *dev);
 237 static void tower_check_for_read_packet (struct lego_usb_tower *dev);
 238 static void tower_interrupt_in_callback (struct urb *urb);
 239 static void tower_interrupt_out_callback (struct urb *urb);
 240
 241 static int  tower_probe (struct usb_interface *interface, const struct usb_device_id *id);
 242 static void tower_disconnect    (struct usb_interface *interface);
 243
 244
 245 /* file operations needed when we register this driver */
 246 static const struct file_operations tower_fops = {
 247         .owner =        THIS_MODULE,
 248         .read  =        tower_read,
 249         .write =        tower_write,
 250         .open =         tower_open,
 251         .release =      tower_release,
 252         .poll =         tower_poll,
 253         .llseek =       tower_llseek,
 254 };
 255
 256 static char *legousbtower_devnode(struct device *dev, umode_t *mode)
 257 {
 258         return kasprintf(GFP_KERNEL, "usb/%s", dev_name(dev));
 259 }
 260
 261 /*
 262  * usb class driver info in order to get a minor number from the usb core,
 263  * and to have the device registered with the driver core
 264  */
 265 static struct usb_class_driver tower_class = {
 266         .name =         "legousbtower%d",
 267         .devnode =      legousbtower_devnode,
 268         .fops =         &tower_fops,
 269         .minor_base =   LEGO_USB_TOWER_MINOR_BASE,
 270 };
 271
 272
 273 /* usb specific object needed to register this driver with the usb subsystem */
 274 static struct usb_driver tower_driver = {
 275         .name =         "legousbtower",
 276         .probe =        tower_probe,
 277         .disconnect =   tower_disconnect,
 278         .id_table =     tower_table,
 279 };
 280
 281
 282 /**
 283  *      lego_usb_tower_debug_data
 284  */
 285 static inline void lego_usb_tower_debug_data(struct device *dev,
 286                                              const char *function, int size,
 287                                              const unsigned char *data)
 288 {
 289         dev_dbg(dev, "%s - length = %d, data = %*ph\n",
 290                 function, size, size, data);
 291 }
 292
 293
 294 /**
 295  *      tower_delete
 296  */
 297 static inline void tower_delete (struct lego_usb_tower *dev)
 298 {
 299         tower_abort_transfers (dev);
 300
 301         /* free data structures */
 302         usb_free_urb(dev->interrupt_in_urb);
 303         usb_free_urb(dev->interrupt_out_urb);
 304         kfree (dev->read_buffer);
 305         kfree (dev->interrupt_in_buffer);
 306         kfree (dev->interrupt_out_buffer);
 307         kfree (dev);
 308 }
 309
 310
 311 /**
 312  *      tower_open
 313  */
 314 static int tower_open (struct inode *inode, struct file *file)
 315 {
 316         struct lego_usb_tower *dev = NULL;
 317         int subminor;
 318         int retval = 0;
 319         struct usb_interface *interface;
 320         struct tower_reset_reply reset_reply;
 321         int result;
 322
 323         nonseekable_open(inode, file);
 324         subminor = iminor(inode);
 325
 326         interface = usb_find_interface (&tower_driver, subminor);
 327
 328         if (!interface) {
 329                 pr_err("error, can't find device for minor %d\n", subminor);
 330                 retval = -ENODEV;
 331                 goto exit;
 332         }
 333
 334         mutex_lock(&open_disc_mutex);
 335         dev = usb_get_intfdata(interface);
 336
 337         if (!dev) {
 338                 mutex_unlock(&open_disc_mutex);
 339                 retval = -ENODEV;
 340                 goto exit;
 341         }
 342
 343         /* lock this device */
 344         if (mutex_lock_interruptible(&dev->lock)) {
 345                 mutex_unlock(&open_disc_mutex);
 346                 retval = -ERESTARTSYS;
 347                 goto exit;
 348         }
 349
 350
 351         /* allow opening only once */
 352         if (dev->open_count) {
 353                 mutex_unlock(&open_disc_mutex);
 354                 retval = -EBUSY;
 355                 goto unlock_exit;
 356         }
 357         dev->open_count = 1;
 358         mutex_unlock(&open_disc_mutex);
 359
 360         /* reset the tower */
 361         result = usb_control_msg (dev->udev,
 362                                   usb_rcvctrlpipe(dev->udev, 0),
 363                                   LEGO_USB_TOWER_REQUEST_RESET,
 364                                   USB_TYPE_VENDOR | USB_DIR_IN | USB_RECIP_DEVICE,
 365                                   0,
 366                                   0,
 367                                   &reset_reply,
 368                                   sizeof(reset_reply),
 369                                   1000);
 370         if (result < 0) {
 371                 dev_err(&dev->udev->dev,
 372                         "LEGO USB Tower reset control request failed\n");
 373                 retval = result;
 374                 goto unlock_exit;
 375         }
 376
 377         /* initialize in direction */
 378         dev->read_buffer_length = 0;
 379         dev->read_packet_length = 0;
 380         usb_fill_int_urb (dev->interrupt_in_urb,
 381                           dev->udev,
 382                           usb_rcvintpipe(dev->udev, dev->interrupt_in_endpoint->bEndpointAddress),
 383                           dev->interrupt_in_buffer,
 384                           usb_endpoint_maxp(dev->interrupt_in_endpoint),
 385                           tower_interrupt_in_callback,
 386                           dev,
 387                           dev->interrupt_in_interval);
 388
 389         dev->interrupt_in_running = 1;
 390         dev->interrupt_in_done = 0;
 391         mb();
 392
 393         retval = usb_submit_urb (dev->interrupt_in_urb, GFP_KERNEL);
 394         if (retval) {
 395                 dev_err(&dev->udev->dev,
 396                         "Couldn't submit interrupt_in_urb %d\n", retval);
 397                 dev->interrupt_in_running = 0;
 398                 dev->open_count = 0;
 399                 goto unlock_exit;
 400         }
 401
 402         /* save device in the file's private structure */
 403         file->private_data = dev;
 404
 405 unlock_exit:
 406         mutex_unlock(&dev->lock);
 407
 408 exit:
 409         return retval;
 410 }
 411
 412 /**
 413  *      tower_release
 414  */
 415 static int tower_release (struct inode *inode, struct file *file)
 416 {
 417         struct lego_usb_tower *dev;
 418         int retval = 0;
 419
 420         dev = file->private_data;
 421
 422         if (dev == NULL) {
 423                 retval = -ENODEV;
 424                 goto exit_nolock;
 425         }
 426
 427         mutex_lock(&open_disc_mutex);
 428         if (mutex_lock_interruptible(&dev->lock)) {
 429                 retval = -ERESTARTSYS;
 430                 goto exit;
 431         }
 432
 433         if (dev->open_count != 1) {
 434                 dev_dbg(&dev->udev->dev, "%s: device not opened exactly once\n",
 435                         __func__);
 436                 retval = -ENODEV;
 437                 goto unlock_exit;
 438         }
 439         if (dev->udev == NULL) {
 440                 /* the device was unplugged before the file was released */
 441
 442                 /* unlock here as tower_delete frees dev */
 443                 mutex_unlock(&dev->lock);
 444                 tower_delete (dev);
 445                 goto exit;
 446         }
 447
 448         /* wait until write transfer is finished */
 449         if (dev->interrupt_out_busy) {
 450                 wait_event_interruptible_timeout (dev->write_wait, !dev->interrupt_out_busy, 2 * HZ);
 451         }
 452         tower_abort_transfers (dev);
 453         dev->open_count = 0;
 454
 455 unlock_exit:
 456         mutex_unlock(&dev->lock);
 457
 458 exit:
 459         mutex_unlock(&open_disc_mutex);
 460 exit_nolock:
 461         return retval;
 462 }
 463
 464
 465 /**
 466  *      tower_abort_transfers
 467  *      aborts transfers and frees associated data structures
 468  */
 469 static void tower_abort_transfers (struct lego_usb_tower *dev)
 470 {
 471         if (dev == NULL)
 472                 return;
 473
 474         /* shutdown transfer */
 475         if (dev->interrupt_in_running) {
 476                 dev->interrupt_in_running = 0;
 477                 mb();
 478                 if (dev->udev)
 479                         usb_kill_urb (dev->interrupt_in_urb);
 480         }
 481         if (dev->interrupt_out_busy && dev->udev)
 482                 usb_kill_urb(dev->interrupt_out_urb);
 483 }
 484
 485
 486 /**
 487  *      tower_check_for_read_packet
 488  *
 489  *      To get correct semantics for signals and non-blocking I/O
 490  *      with packetizing we pretend not to see any data in the read buffer
 491  *      until it has been there unchanged for at least
 492  *      dev->packet_timeout_jiffies, or until the buffer is full.
 493  */
 494 static void tower_check_for_read_packet (struct lego_usb_tower *dev)
 495 {
 496         spin_lock_irq (&dev->read_buffer_lock);
 497         if (!packet_timeout
 498             || time_after(jiffies, dev->read_last_arrival + dev->packet_timeout_jiffies)
 499             || dev->read_buffer_length == read_buffer_size) {
 500                 dev->read_packet_length = dev->read_buffer_length;
 501         }
 502         dev->interrupt_in_done = 0;
 503         spin_unlock_irq (&dev->read_buffer_lock);
 504 }
 505
 506
 507 /**
 508  *      tower_poll
 509  */
 510 static unsigned int tower_poll (struct file *file, poll_table *wait)
 511 {
 512         struct lego_usb_tower *dev;
 513         unsigned int mask = 0;
 514
 515         dev = file->private_data;
 516
 517         if (!dev->udev)
 518                 return POLLERR | POLLHUP;
 519
 520         poll_wait(file, &dev->read_wait, wait);
 521         poll_wait(file, &dev->write_wait, wait);
 522
 523         tower_check_for_read_packet(dev);
 524         if (dev->read_packet_length > 0) {
 525                 mask |= POLLIN | POLLRDNORM;
 526         }
 527         if (!dev->interrupt_out_busy) {
 528                 mask |= POLLOUT | POLLWRNORM;
 529         }
 530
 531         return mask;
 532 }
 533
 534
 535 /**
 536  *      tower_llseek
 537  */
 538 static loff_t tower_llseek (struct file *file, loff_t off, int whence)
 539 {
 540         return -ESPIPE;         /* unseekable */
 541 }
 542
 543
 544 /**
 545  *      tower_read
 546  */
 547 static ssize_t tower_read (struct file *file, char __user *buffer, size_t count, loff_t *ppos)
 548 {
 549         struct lego_usb_tower *dev;
 550         size_t bytes_to_read;
 551         int i;
 552         int retval = 0;
 553         unsigned long timeout = 0;
 554
 555         dev = file->private_data;
 556
 557         /* lock this object */
 558         if (mutex_lock_interruptible(&dev->lock)) {
 559                 retval = -ERESTARTSYS;
 560                 goto exit;
 561         }
 562
 563         /* verify that the device wasn't unplugged */
 564         if (dev->udev == NULL) {
 565                 retval = -ENODEV;
 566                 pr_err("No device or device unplugged %d\n", retval);
 567                 goto unlock_exit;
 568         }
 569
 570         /* verify that we actually have some data to read */
 571         if (count == 0) {
 572                 dev_dbg(&dev->udev->dev, "read request of 0 bytes\n");
 573                 goto unlock_exit;
 574         }
 575
 576         if (read_timeout) {
 577                 timeout = jiffies + msecs_to_jiffies(read_timeout);
 578         }
 579
 580         /* wait for data */
 581         tower_check_for_read_packet (dev);
 582         while (dev->read_packet_length == 0) {
 583                 if (file->f_flags & O_NONBLOCK) {
 584                         retval = -EAGAIN;
 585                         goto unlock_exit;
 586                 }
 587                 retval = wait_event_interruptible_timeout(dev->read_wait, dev->interrupt_in_done, dev->packet_timeout_jiffies);
 588                 if (retval < 0) {
 589                         goto unlock_exit;
 590                 }
 591
 592                 /* reset read timeout during read or write activity */
 593                 if (read_timeout
 594                     && (dev->read_buffer_length || dev->interrupt_out_busy)) {
 595                         timeout = jiffies + msecs_to_jiffies(read_timeout);
 596                 }
 597                 /* check for read timeout */
 598                 if (read_timeout && time_after (jiffies, timeout)) {
 599                         retval = -ETIMEDOUT;
 600                         goto unlock_exit;
 601                 }
 602                 tower_check_for_read_packet (dev);
 603         }
 604
 605         /* copy the data from read_buffer into userspace */
 606         bytes_to_read = min(count, dev->read_packet_length);
 607
 608         if (copy_to_user (buffer, dev->read_buffer, bytes_to_read)) {
 609                 retval = -EFAULT;
 610                 goto unlock_exit;
 611         }
 612
 613         spin_lock_irq (&dev->read_buffer_lock);
 614         dev->read_buffer_length -= bytes_to_read;
 615         dev->read_packet_length -= bytes_to_read;
 616         for (i=0; i<dev->read_buffer_length; i++) {
 617                 dev->read_buffer[i] = dev->read_buffer[i+bytes_to_read];
 618         }
 619         spin_unlock_irq (&dev->read_buffer_lock);
 620
 621         retval = bytes_to_read;
 622
 623 unlock_exit:
 624         /* unlock the device */
 625         mutex_unlock(&dev->lock);
 626
 627 exit:
 628         return retval;
 629 }
 630
 631
 632 /**
 633  *      tower_write
 634  */
 635 static ssize_t tower_write (struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
 636 {
 637         struct lego_usb_tower *dev;
 638         size_t bytes_to_write;
 639         int retval = 0;
 640
 641         dev = file->private_data;
 642
 643         /* lock this object */
 644         if (mutex_lock_interruptible(&dev->lock)) {
 645                 retval = -ERESTARTSYS;
 646                 goto exit;
 647         }
 648
 649         /* verify that the device wasn't unplugged */
 650         if (dev->udev == NULL) {
 651                 retval = -ENODEV;
 652                 pr_err("No device or device unplugged %d\n", retval);
 653                 goto unlock_exit;
 654         }
 655
 656         /* verify that we actually have some data to write */
 657         if (count == 0) {
 658                 dev_dbg(&dev->udev->dev, "write request of 0 bytes\n");
 659                 goto unlock_exit;
 660         }
 661
 662         /* wait until previous transfer is finished */
 663         while (dev->interrupt_out_busy) {
 664                 if (file->f_flags & O_NONBLOCK) {
 665                         retval = -EAGAIN;
 666                         goto unlock_exit;
 667                 }
 668                 retval = wait_event_interruptible (dev->write_wait, !dev->interrupt_out_busy);
 669                 if (retval) {
 670                         goto unlock_exit;
 671                 }
 672         }
 673
 674         /* write the data into interrupt_out_buffer from userspace */
 675         bytes_to_write = min_t(int, count, write_buffer_size);
 676         dev_dbg(&dev->udev->dev, "%s: count = %Zd, bytes_to_write = %Zd\n",
 677                 __func__, count, bytes_to_write);
 678
 679         if (copy_from_user (dev->interrupt_out_buffer, buffer, bytes_to_write)) {
 680                 retval = -EFAULT;
 681                 goto unlock_exit;
 682         }
 683
 684         /* send off the urb */
 685         usb_fill_int_urb(dev->interrupt_out_urb,
 686                          dev->udev,
 687                          usb_sndintpipe(dev->udev, dev->interrupt_out_endpoint->bEndpointAddress),
 688                          dev->interrupt_out_buffer,
 689                          bytes_to_write,
 690                          tower_interrupt_out_callback,
 691                          dev,
 692                          dev->interrupt_out_interval);
 693
 694         dev->interrupt_out_busy = 1;
 695         wmb();
 696
 697         retval = usb_submit_urb (dev->interrupt_out_urb, GFP_KERNEL);
 698         if (retval) {
 699                 dev->interrupt_out_busy = 0;
 700                 dev_err(&dev->udev->dev,
 701                         "Couldn't submit interrupt_out_urb %d\n", retval);
 702                 goto unlock_exit;
 703         }
 704         retval = bytes_to_write;
 705
 706 unlock_exit:
 707         /* unlock the device */
 708         mutex_unlock(&dev->lock);
 709
 710 exit:
 711         return retval;
 712 }
 713
 714
 715 /**
 716  *      tower_interrupt_in_callback
 717  */
 718 static void tower_interrupt_in_callback (struct urb *urb)
 719 {
 720         struct lego_usb_tower *dev = urb->context;
 721         int status = urb->status;
 722         int retval;
 723
 724         lego_usb_tower_debug_data(&dev->udev->dev, __func__,
 725                                   urb->actual_length, urb->transfer_buffer);
 726
 727         if (status) {
 728                 if (status == -ENOENT ||
 729                     status == -ECONNRESET ||
 730                     status == -ESHUTDOWN) {
 731                         goto exit;
 732                 } else {
 733                         dev_dbg(&dev->udev->dev,
 734                                 "%s: nonzero status received: %d\n", __func__,
 735                                 status);
 736                         goto resubmit; /* maybe we can recover */
 737                 }
 738         }
 739
 740         if (urb->actual_length > 0) {
 741                 spin_lock (&dev->read_buffer_lock);
 742                 if (dev->read_buffer_length + urb->actual_length < read_buffer_size) {
 743                         memcpy (dev->read_buffer + dev->read_buffer_length,
 744                                 dev->interrupt_in_buffer,
 745                                 urb->actual_length);
 746                         dev->read_buffer_length += urb->actual_length;
 747                         dev->read_last_arrival = jiffies;
 748                         dev_dbg(&dev->udev->dev, "%s: received %d bytes\n",
 749                                 __func__, urb->actual_length);
 750                 } else {
 751                         pr_warn("read_buffer overflow, %d bytes dropped\n",
 752                                 urb->actual_length);
 753                 }
 754                 spin_unlock (&dev->read_buffer_lock);
 755         }
 756
 757 resubmit:
 758         /* resubmit if we're still running */
 759         if (dev->interrupt_in_running && dev->udev) {
 760                 retval = usb_submit_urb (dev->interrupt_in_urb, GFP_ATOMIC);
 761                 if (retval)
 762                         dev_err(&dev->udev->dev,
 763                                 "%s: usb_submit_urb failed (%d)\n",
 764                                 __func__, retval);
 765         }
 766
 767 exit:
 768         dev->interrupt_in_done = 1;
 769         wake_up_interruptible (&dev->read_wait);
 770 }
 771
 772
 773 /**
 774  *      tower_interrupt_out_callback
 775  */
 776 static void tower_interrupt_out_callback (struct urb *urb)
 777 {
 778         struct lego_usb_tower *dev = urb->context;
 779         int status = urb->status;
 780
 781         lego_usb_tower_debug_data(&dev->udev->dev, __func__,
 782                                   urb->actual_length, urb->transfer_buffer);
 783
 784         /* sync/async unlink faults aren't errors */
 785         if (status && !(status == -ENOENT ||
 786                         status == -ECONNRESET ||
 787                         status == -ESHUTDOWN)) {
 788                 dev_dbg(&dev->udev->dev,
 789                         "%s: nonzero write bulk status received: %d\n", __func__,
 790                         status);
 791         }
 792
 793         dev->interrupt_out_busy = 0;
 794         wake_up_interruptible(&dev->write_wait);
 795 }
 796
 797
 798 /**
 799  *      tower_probe
 800  *
 801  *      Called by the usb core when a new device is connected that it thinks
 802  *      this driver might be interested in.
 803  */
 804 static int tower_probe (struct usb_interface *interface, const struct usb_device_id *id)
 805 {
 806         struct device *idev = &interface->dev;
 807         struct usb_device *udev = interface_to_usbdev(interface);
 808         struct lego_usb_tower *dev = NULL;
 809         struct usb_host_interface *iface_desc;
 810         struct usb_endpoint_descriptor* endpoint;
 811         struct tower_get_version_reply get_version_reply;
 812         int i;
 813         int retval = -ENOMEM;
 814         int result;
 815
 816         /* allocate memory for our device state and initialize it */
 817
 818         dev = kmalloc (sizeof(struct lego_usb_tower), GFP_KERNEL);
 819
 820         if (dev == NULL) {
 821                 dev_err(idev, "Out of memory\n");
 822                 goto exit;
 823         }
 824
 825         mutex_init(&dev->lock);
 826
 827         dev->udev = udev;
 828         dev->open_count = 0;
 829
 830         dev->read_buffer = NULL;
 831         dev->read_buffer_length = 0;
 832         dev->read_packet_length = 0;
 833         spin_lock_init (&dev->read_buffer_lock);
 834         dev->packet_timeout_jiffies = msecs_to_jiffies(packet_timeout);
 835         dev->read_last_arrival = jiffies;
 836
 837         init_waitqueue_head (&dev->read_wait);
 838         init_waitqueue_head (&dev->write_wait);
 839
 840         dev->interrupt_in_buffer = NULL;
 841         dev->interrupt_in_endpoint = NULL;
 842         dev->interrupt_in_urb = NULL;
 843         dev->interrupt_in_running = 0;
 844         dev->interrupt_in_done = 0;
 845
 846         dev->interrupt_out_buffer = NULL;
 847         dev->interrupt_out_endpoint = NULL;
 848         dev->interrupt_out_urb = NULL;
 849         dev->interrupt_out_busy = 0;
 850
 851         iface_desc = interface->cur_altsetting;
 852
 853         /* set up the endpoint information */
 854         for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
 855                 endpoint = &iface_desc->endpoint[i].desc;
 856
 857                 if (usb_endpoint_xfer_int(endpoint)) {
 858                         if (usb_endpoint_dir_in(endpoint))
 859                                 dev->interrupt_in_endpoint = endpoint;
 860                         else
 861                                 dev->interrupt_out_endpoint = endpoint;
 862                 }
 863         }
 864         if(dev->interrupt_in_endpoint == NULL) {
 865                 dev_err(idev, "interrupt in endpoint not found\n");
 866                 goto error;
 867         }
 868         if (dev->interrupt_out_endpoint == NULL) {
 869                 dev_err(idev, "interrupt out endpoint not found\n");
 870                 goto error;
 871         }
 872
 873         dev->read_buffer = kmalloc (read_buffer_size, GFP_KERNEL);
 874         if (!dev->read_buffer) {
 875                 dev_err(idev, "Couldn't allocate read_buffer\n");
 876                 goto error;
 877         }
 878         dev->interrupt_in_buffer = kmalloc (usb_endpoint_maxp(dev->interrupt_in_endpoint), GFP_KERNEL);
 879         if (!dev->interrupt_in_buffer) {
 880                 dev_err(idev, "Couldn't allocate interrupt_in_buffer\n");
 881                 goto error;
 882         }
 883         dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
 884         if (!dev->interrupt_in_urb)
 885                 goto error;
 886         dev->interrupt_out_buffer = kmalloc (write_buffer_size, GFP_KERNEL);
 887         if (!dev->interrupt_out_buffer) {
 888                 dev_err(idev, "Couldn't allocate interrupt_out_buffer\n");
 889                 goto error;
 890         }
 891         dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
 892         if (!dev->interrupt_out_urb)
 893                 goto error;
 894         dev->interrupt_in_interval = interrupt_in_interval ? interrupt_in_interval : dev->interrupt_in_endpoint->bInterval;
 895         dev->interrupt_out_interval = interrupt_out_interval ? interrupt_out_interval : dev->interrupt_out_endpoint->bInterval;
 896
 897         /* we can register the device now, as it is ready */
 898         usb_set_intfdata (interface, dev);
 899
 900         retval = usb_register_dev (interface, &tower_class);
 901
 902         if (retval) {
 903                 /* something prevented us from registering this driver */
 904                 dev_err(idev, "Not able to get a minor for this device.\n");
 905                 usb_set_intfdata (interface, NULL);
 906                 goto error;
 907         }
 908         dev->minor = interface->minor;
 909
 910         /* let the user know what node this device is now attached to */
 911         dev_info(&interface->dev, "LEGO USB Tower #%d now attached to major "
 912                  "%d minor %d\n", (dev->minor - LEGO_USB_TOWER_MINOR_BASE),
 913                  USB_MAJOR, dev->minor);
 914
 915         /* get the firmware version and log it */
 916         result = usb_control_msg (udev,
 917                                   usb_rcvctrlpipe(udev, 0),
 918                                   LEGO_USB_TOWER_REQUEST_GET_VERSION,
 919                                   USB_TYPE_VENDOR | USB_DIR_IN | USB_RECIP_DEVICE,
 920                                   0,
 921                                   0,
 922                                   &get_version_reply,
 923                                   sizeof(get_version_reply),
 924                                   1000);
 925         if (result < 0) {
 926                 dev_err(idev, "LEGO USB Tower get version control request failed\n");
 927                 retval = result;
 928                 goto error;
 929         }
 930         dev_info(&interface->dev, "LEGO USB Tower firmware version is %d.%d "
 931                  "build %d\n", get_version_reply.major,
 932                  get_version_reply.minor,
 933                  le16_to_cpu(get_version_reply.build_no));
 934
 935
 936 exit:
 937         return retval;
 938
 939 error:
 940         tower_delete(dev);
 941         return retval;
 942 }
 943
 944
 945 /**
 946  *      tower_disconnect
 947  *
 948  *      Called by the usb core when the device is removed from the system.
 949  */
 950 static void tower_disconnect (struct usb_interface *interface)
 951 {
 952         struct lego_usb_tower *dev;
 953         int minor;
 954
 955         dev = usb_get_intfdata (interface);
 956         mutex_lock(&open_disc_mutex);
 957         usb_set_intfdata (interface, NULL);
 958
 959         minor = dev->minor;
 960
 961         /* give back our minor */
 962         usb_deregister_dev (interface, &tower_class);
 963
 964         mutex_lock(&dev->lock);
 965         mutex_unlock(&open_disc_mutex);
 966
 967         /* if the device is not opened, then we clean up right now */
 968         if (!dev->open_count) {
 969                 mutex_unlock(&dev->lock);
 970                 tower_delete (dev);
 971         } else {
 972                 dev->udev = NULL;
 973                 /* wake up pollers */
 974                 wake_up_interruptible_all(&dev->read_wait);
 975                 wake_up_interruptible_all(&dev->write_wait);
 976                 mutex_unlock(&dev->lock);
 977         }
 978
 979         dev_info(&interface->dev, "LEGO USB Tower #%d now disconnected\n",
 980                  (minor - LEGO_USB_TOWER_MINOR_BASE));
 981 }
 982
 983 module_usb_driver(tower_driver);
 984
 985 MODULE_AUTHOR(DRIVER_AUTHOR);
 986 MODULE_DESCRIPTION(DRIVER_DESC);
 987 #ifdef MODULE_LICENSE
 988 MODULE_LICENSE("GPL");
 989 #endif