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   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 #include <linux/kernel.h>
  79 #include <linux/errno.h>
  80 #include <linux/init.h>
  81 #include <linux/slab.h>
  82 #include <linux/module.h>
  83 #include <linux/completion.h>
  84 #include <linux/mutex.h>
  85 #include <asm/uaccess.h>
  86 #include <linux/usb.h>
  87 #include <linux/poll.h>
  88
  89
  90 #ifdef CONFIG_USB_DEBUG
  91         static int debug = 4;
  92 #else
  93         static int debug = 0;
  94 #endif
  95
  96 /* Use our own dbg macro */
  97 #undef dbg
  98 #define dbg(lvl, format, arg...) do { if (debug >= lvl) printk(KERN_DEBUG  __FILE__ ": " format "\n", ## arg); } while (0)
  99
 100
 101 /* Version Information */
 102 #define DRIVER_VERSION "v0.96"
 103 #define DRIVER_AUTHOR "Juergen Stuber <starblue@sourceforge.net>"
 104 #define DRIVER_DESC "LEGO USB Tower Driver"
 105
 106 /* Module parameters */
 107 module_param(debug, int, S_IRUGO | S_IWUSR);
 108 MODULE_PARM_DESC(debug, "Debug enabled or not");
 109
 110 /* The defaults are chosen to work with the latest versions of leJOS and NQC.
 111  */
 112
 113 /* Some legacy software likes to receive packets in one piece.
 114  * In this case read_buffer_size should exceed the maximal packet length
 115  * (417 for datalog uploads), and packet_timeout should be set.
 116  */
 117 static int read_buffer_size = 480;
 118 module_param(read_buffer_size, int, 0);
 119 MODULE_PARM_DESC(read_buffer_size, "Read buffer size");
 120
 121 /* Some legacy software likes to send packets in one piece.
 122  * In this case write_buffer_size should exceed the maximal packet length
 123  * (417 for firmware and program downloads).
 124  * A problem with long writes is that the following read may time out
 125  * if the software is not prepared to wait long enough.
 126  */
 127 static int write_buffer_size = 480;
 128 module_param(write_buffer_size, int, 0);
 129 MODULE_PARM_DESC(write_buffer_size, "Write buffer size");
 130
 131 /* Some legacy software expects reads to contain whole LASM packets.
 132  * To achieve this, characters which arrive before a packet timeout
 133  * occurs will be returned in a single read operation.
 134  * A problem with long reads is that the software may time out
 135  * if it is not prepared to wait long enough.
 136  * The packet timeout should be greater than the time between the
 137  * reception of subsequent characters, which should arrive about
 138  * every 5ms for the standard 2400 baud.
 139  * Set it to 0 to disable.
 140  */
 141 static int packet_timeout = 50;
 142 module_param(packet_timeout, int, 0);
 143 MODULE_PARM_DESC(packet_timeout, "Packet timeout in ms");
 144
 145 /* Some legacy software expects blocking reads to time out.
 146  * Timeout occurs after the specified time of read and write inactivity.
 147  * Set it to 0 to disable.
 148  */
 149 static int read_timeout = 200;
 150 module_param(read_timeout, int, 0);
 151 MODULE_PARM_DESC(read_timeout, "Read timeout in ms");
 152
 153 /* As of kernel version 2.6.4 ehci-hcd uses an
 154  * "only one interrupt transfer per frame" shortcut
 155  * to simplify the scheduling of periodic transfers.
 156  * This conflicts with our standard 1ms intervals for in and out URBs.
 157  * We use default intervals of 2ms for in and 8ms for out transfers,
 158  * which is fast enough for 2400 baud and allows a small additional load.
 159  * Increase the interval to allow more devices that do interrupt transfers,
 160  * or set to 0 to use the standard interval from the endpoint descriptors.
 161  */
 162 static int interrupt_in_interval = 2;
 163 module_param(interrupt_in_interval, int, 0);
 164 MODULE_PARM_DESC(interrupt_in_interval, "Interrupt in interval in ms");
 165
 166 static int interrupt_out_interval = 8;
 167 module_param(interrupt_out_interval, int, 0);
 168 MODULE_PARM_DESC(interrupt_out_interval, "Interrupt out interval in ms");
 169
 170 /* Define these values to match your device */
 171 #define LEGO_USB_TOWER_VENDOR_ID        0x0694
 172 #define LEGO_USB_TOWER_PRODUCT_ID       0x0001
 173
 174 /* Vendor requests */
 175 #define LEGO_USB_TOWER_REQUEST_RESET            0x04
 176 #define LEGO_USB_TOWER_REQUEST_GET_VERSION      0xFD
 177
 178 struct tower_reset_reply {
 179         __le16 size;            /* little-endian */
 180         __u8 err_code;
 181         __u8 spare;
 182 } __attribute__ ((packed));
 183
 184 struct tower_get_version_reply {
 185         __le16 size;            /* little-endian */
 186         __u8 err_code;
 187         __u8 spare;
 188         __u8 major;
 189         __u8 minor;
 190         __le16 build_no;                /* little-endian */
 191 } __attribute__ ((packed));
 192
 193
 194 /* table of devices that work with this driver */
 195 static struct usb_device_id tower_table [] = {
 196         { USB_DEVICE(LEGO_USB_TOWER_VENDOR_ID, LEGO_USB_TOWER_PRODUCT_ID) },
 197         { }                                     /* Terminating entry */
 198 };
 199
 200 MODULE_DEVICE_TABLE (usb, tower_table);
 201 static DEFINE_MUTEX(open_disc_mutex);
 202
 203 #define LEGO_USB_TOWER_MINOR_BASE       160
 204
 205
 206 /* Structure to hold all of our device specific stuff */
 207 struct lego_usb_tower {
 208         struct mutex            lock;           /* locks this structure */
 209         struct usb_device*      udev;           /* save off the usb device pointer */
 210         unsigned char           minor;          /* the starting minor number for this device */
 211
 212         int                     open_count;     /* number of times this port has been opened */
 213
 214         char*                   read_buffer;
 215         size_t                  read_buffer_length; /* this much came in */
 216         size_t                  read_packet_length; /* this much will be returned on read */
 217         spinlock_t              read_buffer_lock;
 218         int                     packet_timeout_jiffies;
 219         unsigned long           read_last_arrival;
 220
 221         wait_queue_head_t       read_wait;
 222         wait_queue_head_t       write_wait;
 223
 224         char*                   interrupt_in_buffer;
 225         struct usb_endpoint_descriptor* interrupt_in_endpoint;
 226         struct urb*             interrupt_in_urb;
 227         int                     interrupt_in_interval;
 228         int                     interrupt_in_running;
 229         int                     interrupt_in_done;
 230
 231         char*                   interrupt_out_buffer;
 232         struct usb_endpoint_descriptor* interrupt_out_endpoint;
 233         struct urb*             interrupt_out_urb;
 234         int                     interrupt_out_interval;
 235         int                     interrupt_out_busy;
 236
 237 };
 238
 239
 240 /* local function prototypes */
 241 static ssize_t tower_read       (struct file *file, char __user *buffer, size_t count, loff_t *ppos);
 242 static ssize_t tower_write      (struct file *file, const char __user *buffer, size_t count, loff_t *ppos);
 243 static inline void tower_delete (struct lego_usb_tower *dev);
 244 static int tower_open           (struct inode *inode, struct file *file);
 245 static int tower_release        (struct inode *inode, struct file *file);
 246 static unsigned int tower_poll  (struct file *file, poll_table *wait);
 247 static loff_t tower_llseek      (struct file *file, loff_t off, int whence);
 248
 249 static void tower_abort_transfers (struct lego_usb_tower *dev);
 250 static void tower_check_for_read_packet (struct lego_usb_tower *dev);
 251 static void tower_interrupt_in_callback (struct urb *urb);
 252 static void tower_interrupt_out_callback (struct urb *urb);
 253
 254 static int  tower_probe (struct usb_interface *interface, const struct usb_device_id *id);
 255 static void tower_disconnect    (struct usb_interface *interface);
 256
 257
 258 /* file operations needed when we register this driver */
 259 static const struct file_operations tower_fops = {
 260         .owner =        THIS_MODULE,
 261         .read  =        tower_read,
 262         .write =        tower_write,
 263         .open =         tower_open,
 264         .release =      tower_release,
 265         .poll =         tower_poll,
 266         .llseek =       tower_llseek,
 267 };
 268
 269 static char *legousbtower_devnode(struct device *dev, mode_t *mode)
 270 {
 271         return kasprintf(GFP_KERNEL, "usb/%s", dev_name(dev));
 272 }
 273
 274 /*
 275  * usb class driver info in order to get a minor number from the usb core,
 276  * and to have the device registered with the driver core
 277  */
 278 static struct usb_class_driver tower_class = {
 279         .name =         "legousbtower%d",
 280         .devnode =      legousbtower_devnode,
 281         .fops =         &tower_fops,
 282         .minor_base =   LEGO_USB_TOWER_MINOR_BASE,
 283 };
 284
 285
 286 /* usb specific object needed to register this driver with the usb subsystem */
 287 static struct usb_driver tower_driver = {
 288         .name =         "legousbtower",
 289         .probe =        tower_probe,
 290         .disconnect =   tower_disconnect,
 291         .id_table =     tower_table,
 292 };
 293
 294
 295 /**
 296  *      lego_usb_tower_debug_data
 297  */
 298 static inline void lego_usb_tower_debug_data (int level, const char *function, int size, const unsigned char *data)
 299 {
 300         int i;
 301
 302         if (debug < level)
 303                 return;
 304
 305         printk (KERN_DEBUG __FILE__": %s - length = %d, data = ", function, size);
 306         for (i = 0; i < size; ++i) {
 307                 printk ("%.2x ", data[i]);
 308         }
 309         printk ("\n");
 310 }
 311
 312
 313 /**
 314  *      tower_delete
 315  */
 316 static inline void tower_delete (struct lego_usb_tower *dev)
 317 {
 318         dbg(2, "%s: enter", __func__);
 319
 320         tower_abort_transfers (dev);
 321
 322         /* free data structures */
 323         usb_free_urb(dev->interrupt_in_urb);
 324         usb_free_urb(dev->interrupt_out_urb);
 325         kfree (dev->read_buffer);
 326         kfree (dev->interrupt_in_buffer);
 327         kfree (dev->interrupt_out_buffer);
 328         kfree (dev);
 329
 330         dbg(2, "%s: leave", __func__);
 331 }
 332
 333
 334 /**
 335  *      tower_open
 336  */
 337 static int tower_open (struct inode *inode, struct file *file)
 338 {
 339         struct lego_usb_tower *dev = NULL;
 340         int subminor;
 341         int retval = 0;
 342         struct usb_interface *interface;
 343         struct tower_reset_reply reset_reply;
 344         int result;
 345
 346         dbg(2, "%s: enter", __func__);
 347
 348         nonseekable_open(inode, file);
 349         subminor = iminor(inode);
 350
 351         interface = usb_find_interface (&tower_driver, subminor);
 352
 353         if (!interface) {
 354                 err ("%s - error, can't find device for minor %d",
 355                      __func__, subminor);
 356                 retval = -ENODEV;
 357                 goto exit;
 358         }
 359
 360         mutex_lock(&open_disc_mutex);
 361         dev = usb_get_intfdata(interface);
 362
 363         if (!dev) {
 364                 mutex_unlock(&open_disc_mutex);
 365                 retval = -ENODEV;
 366                 goto exit;
 367         }
 368
 369         /* lock this device */
 370         if (mutex_lock_interruptible(&dev->lock)) {
 371                 mutex_unlock(&open_disc_mutex);
 372                 retval = -ERESTARTSYS;
 373                 goto exit;
 374         }
 375
 376
 377         /* allow opening only once */
 378         if (dev->open_count) {
 379                 mutex_unlock(&open_disc_mutex);
 380                 retval = -EBUSY;
 381                 goto unlock_exit;
 382         }
 383         dev->open_count = 1;
 384         mutex_unlock(&open_disc_mutex);
 385
 386         /* reset the tower */
 387         result = usb_control_msg (dev->udev,
 388                                   usb_rcvctrlpipe(dev->udev, 0),
 389                                   LEGO_USB_TOWER_REQUEST_RESET,
 390                                   USB_TYPE_VENDOR | USB_DIR_IN | USB_RECIP_DEVICE,
 391                                   0,
 392                                   0,
 393                                   &reset_reply,
 394                                   sizeof(reset_reply),
 395                                   1000);
 396         if (result < 0) {
 397                 err("LEGO USB Tower reset control request failed");
 398                 retval = result;
 399                 goto unlock_exit;
 400         }
 401
 402         /* initialize in direction */
 403         dev->read_buffer_length = 0;
 404         dev->read_packet_length = 0;
 405         usb_fill_int_urb (dev->interrupt_in_urb,
 406                           dev->udev,
 407                           usb_rcvintpipe(dev->udev, dev->interrupt_in_endpoint->bEndpointAddress),
 408                           dev->interrupt_in_buffer,
 409                           le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize),
 410                           tower_interrupt_in_callback,
 411                           dev,
 412                           dev->interrupt_in_interval);
 413
 414         dev->interrupt_in_running = 1;
 415         dev->interrupt_in_done = 0;
 416         mb();
 417
 418         retval = usb_submit_urb (dev->interrupt_in_urb, GFP_KERNEL);
 419         if (retval) {
 420                 err("Couldn't submit interrupt_in_urb %d", retval);
 421                 dev->interrupt_in_running = 0;
 422                 dev->open_count = 0;
 423                 goto unlock_exit;
 424         }
 425
 426         /* save device in the file's private structure */
 427         file->private_data = dev;
 428
 429 unlock_exit:
 430         mutex_unlock(&dev->lock);
 431
 432 exit:
 433         dbg(2, "%s: leave, return value %d ", __func__, retval);
 434
 435         return retval;
 436 }
 437
 438 /**
 439  *      tower_release
 440  */
 441 static int tower_release (struct inode *inode, struct file *file)
 442 {
 443         struct lego_usb_tower *dev;
 444         int retval = 0;
 445
 446         dbg(2, "%s: enter", __func__);
 447
 448         dev = (struct lego_usb_tower *)file->private_data;
 449
 450         if (dev == NULL) {
 451                 dbg(1, "%s: object is NULL", __func__);
 452                 retval = -ENODEV;
 453                 goto exit_nolock;
 454         }
 455
 456         mutex_lock(&open_disc_mutex);
 457         if (mutex_lock_interruptible(&dev->lock)) {
 458                 retval = -ERESTARTSYS;
 459                 goto exit;
 460         }
 461
 462         if (dev->open_count != 1) {
 463                 dbg(1, "%s: device not opened exactly once", __func__);
 464                 retval = -ENODEV;
 465                 goto unlock_exit;
 466         }
 467         if (dev->udev == NULL) {
 468                 /* the device was unplugged before the file was released */
 469
 470                 /* unlock here as tower_delete frees dev */
 471                 mutex_unlock(&dev->lock);
 472                 tower_delete (dev);
 473                 goto exit;
 474         }
 475
 476         /* wait until write transfer is finished */
 477         if (dev->interrupt_out_busy) {
 478                 wait_event_interruptible_timeout (dev->write_wait, !dev->interrupt_out_busy, 2 * HZ);
 479         }
 480         tower_abort_transfers (dev);
 481         dev->open_count = 0;
 482
 483 unlock_exit:
 484         mutex_unlock(&dev->lock);
 485
 486 exit:
 487         mutex_unlock(&open_disc_mutex);
 488 exit_nolock:
 489         dbg(2, "%s: leave, return value %d", __func__, retval);
 490         return retval;
 491 }
 492
 493
 494 /**
 495  *      tower_abort_transfers
 496  *      aborts transfers and frees associated data structures
 497  */
 498 static void tower_abort_transfers (struct lego_usb_tower *dev)
 499 {
 500         dbg(2, "%s: enter", __func__);
 501
 502         if (dev == NULL) {
 503                 dbg(1, "%s: dev is null", __func__);
 504                 goto exit;
 505         }
 506
 507         /* shutdown transfer */
 508         if (dev->interrupt_in_running) {
 509                 dev->interrupt_in_running = 0;
 510                 mb();
 511                 if (dev->udev)
 512                         usb_kill_urb (dev->interrupt_in_urb);
 513         }
 514         if (dev->interrupt_out_busy && dev->udev)
 515                 usb_kill_urb(dev->interrupt_out_urb);
 516
 517 exit:
 518         dbg(2, "%s: leave", __func__);
 519 }
 520
 521
 522 /**
 523  *      tower_check_for_read_packet
 524  *
 525  *      To get correct semantics for signals and non-blocking I/O
 526  *      with packetizing we pretend not to see any data in the read buffer
 527  *      until it has been there unchanged for at least
 528  *      dev->packet_timeout_jiffies, or until the buffer is full.
 529  */
 530 static void tower_check_for_read_packet (struct lego_usb_tower *dev)
 531 {
 532         spin_lock_irq (&dev->read_buffer_lock);
 533         if (!packet_timeout
 534             || time_after(jiffies, dev->read_last_arrival + dev->packet_timeout_jiffies)
 535             || dev->read_buffer_length == read_buffer_size) {
 536                 dev->read_packet_length = dev->read_buffer_length;
 537         }
 538         dev->interrupt_in_done = 0;
 539         spin_unlock_irq (&dev->read_buffer_lock);
 540 }
 541
 542
 543 /**
 544  *      tower_poll
 545  */
 546 static unsigned int tower_poll (struct file *file, poll_table *wait)
 547 {
 548         struct lego_usb_tower *dev;
 549         unsigned int mask = 0;
 550
 551         dbg(2, "%s: enter", __func__);
 552
 553         dev = file->private_data;
 554
 555         poll_wait(file, &dev->read_wait, wait);
 556         poll_wait(file, &dev->write_wait, wait);
 557
 558         tower_check_for_read_packet(dev);
 559         if (dev->read_packet_length > 0) {
 560                 mask |= POLLIN | POLLRDNORM;
 561         }
 562         if (!dev->interrupt_out_busy) {
 563                 mask |= POLLOUT | POLLWRNORM;
 564         }
 565
 566         dbg(2, "%s: leave, mask = %d", __func__, mask);
 567
 568         return mask;
 569 }
 570
 571
 572 /**
 573  *      tower_llseek
 574  */
 575 static loff_t tower_llseek (struct file *file, loff_t off, int whence)
 576 {
 577         return -ESPIPE;         /* unseekable */
 578 }
 579
 580
 581 /**
 582  *      tower_read
 583  */
 584 static ssize_t tower_read (struct file *file, char __user *buffer, size_t count, loff_t *ppos)
 585 {
 586         struct lego_usb_tower *dev;
 587         size_t bytes_to_read;
 588         int i;
 589         int retval = 0;
 590         unsigned long timeout = 0;
 591
 592         dbg(2, "%s: enter, count = %Zd", __func__, count);
 593
 594         dev = (struct lego_usb_tower *)file->private_data;
 595
 596         /* lock this object */
 597         if (mutex_lock_interruptible(&dev->lock)) {
 598                 retval = -ERESTARTSYS;
 599                 goto exit;
 600         }
 601
 602         /* verify that the device wasn't unplugged */
 603         if (dev->udev == NULL) {
 604                 retval = -ENODEV;
 605                 err("No device or device unplugged %d", retval);
 606                 goto unlock_exit;
 607         }
 608
 609         /* verify that we actually have some data to read */
 610         if (count == 0) {
 611                 dbg(1, "%s: read request of 0 bytes", __func__);
 612                 goto unlock_exit;
 613         }
 614
 615         if (read_timeout) {
 616                 timeout = jiffies + read_timeout * HZ / 1000;
 617         }
 618
 619         /* wait for data */
 620         tower_check_for_read_packet (dev);
 621         while (dev->read_packet_length == 0) {
 622                 if (file->f_flags & O_NONBLOCK) {
 623                         retval = -EAGAIN;
 624                         goto unlock_exit;
 625                 }
 626                 retval = wait_event_interruptible_timeout(dev->read_wait, dev->interrupt_in_done, dev->packet_timeout_jiffies);
 627                 if (retval < 0) {
 628                         goto unlock_exit;
 629                 }
 630
 631                 /* reset read timeout during read or write activity */
 632                 if (read_timeout
 633                     && (dev->read_buffer_length || dev->interrupt_out_busy)) {
 634                         timeout = jiffies + read_timeout * HZ / 1000;
 635                 }
 636                 /* check for read timeout */
 637                 if (read_timeout && time_after (jiffies, timeout)) {
 638                         retval = -ETIMEDOUT;
 639                         goto unlock_exit;
 640                 }
 641                 tower_check_for_read_packet (dev);
 642         }
 643
 644         /* copy the data from read_buffer into userspace */
 645         bytes_to_read = min(count, dev->read_packet_length);
 646
 647         if (copy_to_user (buffer, dev->read_buffer, bytes_to_read)) {
 648                 retval = -EFAULT;
 649                 goto unlock_exit;
 650         }
 651
 652         spin_lock_irq (&dev->read_buffer_lock);
 653         dev->read_buffer_length -= bytes_to_read;
 654         dev->read_packet_length -= bytes_to_read;
 655         for (i=0; i<dev->read_buffer_length; i++) {
 656                 dev->read_buffer[i] = dev->read_buffer[i+bytes_to_read];
 657         }
 658         spin_unlock_irq (&dev->read_buffer_lock);
 659
 660         retval = bytes_to_read;
 661
 662 unlock_exit:
 663         /* unlock the device */
 664         mutex_unlock(&dev->lock);
 665
 666 exit:
 667         dbg(2, "%s: leave, return value %d", __func__, retval);
 668         return retval;
 669 }
 670
 671
 672 /**
 673  *      tower_write
 674  */
 675 static ssize_t tower_write (struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
 676 {
 677         struct lego_usb_tower *dev;
 678         size_t bytes_to_write;
 679         int retval = 0;
 680
 681         dbg(2, "%s: enter, count = %Zd", __func__, count);
 682
 683         dev = (struct lego_usb_tower *)file->private_data;
 684
 685         /* lock this object */
 686         if (mutex_lock_interruptible(&dev->lock)) {
 687                 retval = -ERESTARTSYS;
 688                 goto exit;
 689         }
 690
 691         /* verify that the device wasn't unplugged */
 692         if (dev->udev == NULL) {
 693                 retval = -ENODEV;
 694                 err("No device or device unplugged %d", retval);
 695                 goto unlock_exit;
 696         }
 697
 698         /* verify that we actually have some data to write */
 699         if (count == 0) {
 700                 dbg(1, "%s: write request of 0 bytes", __func__);
 701                 goto unlock_exit;
 702         }
 703
 704         /* wait until previous transfer is finished */
 705         while (dev->interrupt_out_busy) {
 706                 if (file->f_flags & O_NONBLOCK) {
 707                         retval = -EAGAIN;
 708                         goto unlock_exit;
 709                 }
 710                 retval = wait_event_interruptible (dev->write_wait, !dev->interrupt_out_busy);
 711                 if (retval) {
 712                         goto unlock_exit;
 713                 }
 714         }
 715
 716         /* write the data into interrupt_out_buffer from userspace */
 717         bytes_to_write = min_t(int, count, write_buffer_size);
 718         dbg(4, "%s: count = %Zd, bytes_to_write = %Zd", __func__, count, bytes_to_write);
 719
 720         if (copy_from_user (dev->interrupt_out_buffer, buffer, bytes_to_write)) {
 721                 retval = -EFAULT;
 722                 goto unlock_exit;
 723         }
 724
 725         /* send off the urb */
 726         usb_fill_int_urb(dev->interrupt_out_urb,
 727                          dev->udev,
 728                          usb_sndintpipe(dev->udev, dev->interrupt_out_endpoint->bEndpointAddress),
 729                          dev->interrupt_out_buffer,
 730                          bytes_to_write,
 731                          tower_interrupt_out_callback,
 732                          dev,
 733                          dev->interrupt_out_interval);
 734
 735         dev->interrupt_out_busy = 1;
 736         wmb();
 737
 738         retval = usb_submit_urb (dev->interrupt_out_urb, GFP_KERNEL);
 739         if (retval) {
 740                 dev->interrupt_out_busy = 0;
 741                 err("Couldn't submit interrupt_out_urb %d", retval);
 742                 goto unlock_exit;
 743         }
 744         retval = bytes_to_write;
 745
 746 unlock_exit:
 747         /* unlock the device */
 748         mutex_unlock(&dev->lock);
 749
 750 exit:
 751         dbg(2, "%s: leave, return value %d", __func__, retval);
 752
 753         return retval;
 754 }
 755
 756
 757 /**
 758  *      tower_interrupt_in_callback
 759  */
 760 static void tower_interrupt_in_callback (struct urb *urb)
 761 {
 762         struct lego_usb_tower *dev = urb->context;
 763         int status = urb->status;
 764         int retval;
 765
 766         dbg(4, "%s: enter, status %d", __func__, status);
 767
 768         lego_usb_tower_debug_data(5, __func__, urb->actual_length, urb->transfer_buffer);
 769
 770         if (status) {
 771                 if (status == -ENOENT ||
 772                     status == -ECONNRESET ||
 773                     status == -ESHUTDOWN) {
 774                         goto exit;
 775                 } else {
 776                         dbg(1, "%s: nonzero status received: %d", __func__, status);
 777                         goto resubmit; /* maybe we can recover */
 778                 }
 779         }
 780
 781         if (urb->actual_length > 0) {
 782                 spin_lock (&dev->read_buffer_lock);
 783                 if (dev->read_buffer_length + urb->actual_length < read_buffer_size) {
 784                         memcpy (dev->read_buffer + dev->read_buffer_length,
 785                                 dev->interrupt_in_buffer,
 786                                 urb->actual_length);
 787                         dev->read_buffer_length += urb->actual_length;
 788                         dev->read_last_arrival = jiffies;
 789                         dbg(3, "%s: received %d bytes", __func__, urb->actual_length);
 790                 } else {
 791                         printk(KERN_WARNING "%s: read_buffer overflow, %d bytes dropped", __func__, urb->actual_length);
 792                 }
 793                 spin_unlock (&dev->read_buffer_lock);
 794         }
 795
 796 resubmit:
 797         /* resubmit if we're still running */
 798         if (dev->interrupt_in_running && dev->udev) {
 799                 retval = usb_submit_urb (dev->interrupt_in_urb, GFP_ATOMIC);
 800                 if (retval) {
 801                         err("%s: usb_submit_urb failed (%d)", __func__, retval);
 802                 }
 803         }
 804
 805 exit:
 806         dev->interrupt_in_done = 1;
 807         wake_up_interruptible (&dev->read_wait);
 808
 809         lego_usb_tower_debug_data(5, __func__, urb->actual_length, urb->transfer_buffer);
 810         dbg(4, "%s: leave, status %d", __func__, status);
 811 }
 812
 813
 814 /**
 815  *      tower_interrupt_out_callback
 816  */
 817 static void tower_interrupt_out_callback (struct urb *urb)
 818 {
 819         struct lego_usb_tower *dev = urb->context;
 820         int status = urb->status;
 821
 822         dbg(4, "%s: enter, status %d", __func__, status);
 823         lego_usb_tower_debug_data(5, __func__, urb->actual_length, urb->transfer_buffer);
 824
 825         /* sync/async unlink faults aren't errors */
 826         if (status && !(status == -ENOENT ||
 827                         status == -ECONNRESET ||
 828                         status == -ESHUTDOWN)) {
 829                 dbg(1, "%s - nonzero write bulk status received: %d",
 830                     __func__, status);
 831         }
 832
 833         dev->interrupt_out_busy = 0;
 834         wake_up_interruptible(&dev->write_wait);
 835
 836         lego_usb_tower_debug_data(5, __func__, urb->actual_length, urb->transfer_buffer);
 837         dbg(4, "%s: leave, status %d", __func__, status);
 838 }
 839
 840
 841 /**
 842  *      tower_probe
 843  *
 844  *      Called by the usb core when a new device is connected that it thinks
 845  *      this driver might be interested in.
 846  */
 847 static int tower_probe (struct usb_interface *interface, const struct usb_device_id *id)
 848 {
 849         struct usb_device *udev = interface_to_usbdev(interface);
 850         struct lego_usb_tower *dev = NULL;
 851         struct usb_host_interface *iface_desc;
 852         struct usb_endpoint_descriptor* endpoint;
 853         struct tower_get_version_reply get_version_reply;
 854         int i;
 855         int retval = -ENOMEM;
 856         int result;
 857
 858         dbg(2, "%s: enter", __func__);
 859
 860         if (udev == NULL)
 861                 dev_info(&interface->dev, "udev is NULL.\n");
 862
 863         /* allocate memory for our device state and initialize it */
 864
 865         dev = kmalloc (sizeof(struct lego_usb_tower), GFP_KERNEL);
 866
 867         if (dev == NULL) {
 868                 err ("Out of memory");
 869                 goto exit;
 870         }
 871
 872         mutex_init(&dev->lock);
 873
 874         dev->udev = udev;
 875         dev->open_count = 0;
 876
 877         dev->read_buffer = NULL;
 878         dev->read_buffer_length = 0;
 879         dev->read_packet_length = 0;
 880         spin_lock_init (&dev->read_buffer_lock);
 881         dev->packet_timeout_jiffies = packet_timeout * HZ / 1000;
 882         dev->read_last_arrival = jiffies;
 883
 884         init_waitqueue_head (&dev->read_wait);
 885         init_waitqueue_head (&dev->write_wait);
 886
 887         dev->interrupt_in_buffer = NULL;
 888         dev->interrupt_in_endpoint = NULL;
 889         dev->interrupt_in_urb = NULL;
 890         dev->interrupt_in_running = 0;
 891         dev->interrupt_in_done = 0;
 892
 893         dev->interrupt_out_buffer = NULL;
 894         dev->interrupt_out_endpoint = NULL;
 895         dev->interrupt_out_urb = NULL;
 896         dev->interrupt_out_busy = 0;
 897
 898         iface_desc = interface->cur_altsetting;
 899
 900         /* set up the endpoint information */
 901         for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
 902                 endpoint = &iface_desc->endpoint[i].desc;
 903
 904                 if (usb_endpoint_xfer_int(endpoint)) {
 905                         if (usb_endpoint_dir_in(endpoint))
 906                                 dev->interrupt_in_endpoint = endpoint;
 907                         else
 908                                 dev->interrupt_out_endpoint = endpoint;
 909                 }
 910         }
 911         if(dev->interrupt_in_endpoint == NULL) {
 912                 err("interrupt in endpoint not found");
 913                 goto error;
 914         }
 915         if (dev->interrupt_out_endpoint == NULL) {
 916                 err("interrupt out endpoint not found");
 917                 goto error;
 918         }
 919
 920         dev->read_buffer = kmalloc (read_buffer_size, GFP_KERNEL);
 921         if (!dev->read_buffer) {
 922                 err("Couldn't allocate read_buffer");
 923                 goto error;
 924         }
 925         dev->interrupt_in_buffer = kmalloc (le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize), GFP_KERNEL);
 926         if (!dev->interrupt_in_buffer) {
 927                 err("Couldn't allocate interrupt_in_buffer");
 928                 goto error;
 929         }
 930         dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
 931         if (!dev->interrupt_in_urb) {
 932                 err("Couldn't allocate interrupt_in_urb");
 933                 goto error;
 934         }
 935         dev->interrupt_out_buffer = kmalloc (write_buffer_size, GFP_KERNEL);
 936         if (!dev->interrupt_out_buffer) {
 937                 err("Couldn't allocate interrupt_out_buffer");
 938                 goto error;
 939         }
 940         dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
 941         if (!dev->interrupt_out_urb) {
 942                 err("Couldn't allocate interrupt_out_urb");
 943                 goto error;
 944         }
 945         dev->interrupt_in_interval = interrupt_in_interval ? interrupt_in_interval : dev->interrupt_in_endpoint->bInterval;
 946         dev->interrupt_out_interval = interrupt_out_interval ? interrupt_out_interval : dev->interrupt_out_endpoint->bInterval;
 947
 948         /* we can register the device now, as it is ready */
 949         usb_set_intfdata (interface, dev);
 950
 951         retval = usb_register_dev (interface, &tower_class);
 952
 953         if (retval) {
 954                 /* something prevented us from registering this driver */
 955                 err ("Not able to get a minor for this device.");
 956                 usb_set_intfdata (interface, NULL);
 957                 goto error;
 958         }
 959         dev->minor = interface->minor;
 960
 961         /* let the user know what node this device is now attached to */
 962         dev_info(&interface->dev, "LEGO USB Tower #%d now attached to major "
 963                  "%d minor %d\n", (dev->minor - LEGO_USB_TOWER_MINOR_BASE),
 964                  USB_MAJOR, dev->minor);
 965
 966         /* get the firmware version and log it */
 967         result = usb_control_msg (udev,
 968                                   usb_rcvctrlpipe(udev, 0),
 969                                   LEGO_USB_TOWER_REQUEST_GET_VERSION,
 970                                   USB_TYPE_VENDOR | USB_DIR_IN | USB_RECIP_DEVICE,
 971                                   0,
 972                                   0,
 973                                   &get_version_reply,
 974                                   sizeof(get_version_reply),
 975                                   1000);
 976         if (result < 0) {
 977                 err("LEGO USB Tower get version control request failed");
 978                 retval = result;
 979                 goto error;
 980         }
 981         dev_info(&interface->dev, "LEGO USB Tower firmware version is %d.%d "
 982                  "build %d\n", get_version_reply.major,
 983                  get_version_reply.minor,
 984                  le16_to_cpu(get_version_reply.build_no));
 985
 986
 987 exit:
 988         dbg(2, "%s: leave, return value 0x%.8lx (dev)", __func__, (long) dev);
 989
 990         return retval;
 991
 992 error:
 993         tower_delete(dev);
 994         return retval;
 995 }
 996
 997
 998 /**
 999  *      tower_disconnect
1000  *
1001  *      Called by the usb core when the device is removed from the system.
1002  */
1003 static void tower_disconnect (struct usb_interface *interface)
1004 {
1005         struct lego_usb_tower *dev;
1006         int minor;
1007
1008         dbg(2, "%s: enter", __func__);
1009
1010         dev = usb_get_intfdata (interface);
1011         mutex_lock(&open_disc_mutex);
1012         usb_set_intfdata (interface, NULL);
1013
1014         minor = dev->minor;
1015
1016         /* give back our minor */
1017         usb_deregister_dev (interface, &tower_class);
1018
1019         mutex_lock(&dev->lock);
1020         mutex_unlock(&open_disc_mutex);
1021
1022         /* if the device is not opened, then we clean up right now */
1023         if (!dev->open_count) {
1024                 mutex_unlock(&dev->lock);
1025                 tower_delete (dev);
1026         } else {
1027                 dev->udev = NULL;
1028                 mutex_unlock(&dev->lock);
1029         }
1030
1031         dev_info(&interface->dev, "LEGO USB Tower #%d now disconnected\n",
1032                  (minor - LEGO_USB_TOWER_MINOR_BASE));
1033
1034         dbg(2, "%s: leave", __func__);
1035 }
1036
1037
1038
1039 /**
1040  *      lego_usb_tower_init
1041  */
1042 static int __init lego_usb_tower_init(void)
1043 {
1044         int result;
1045         int retval = 0;
1046
1047         dbg(2, "%s: enter", __func__);
1048
1049         /* register this driver with the USB subsystem */
1050         result = usb_register(&tower_driver);
1051         if (result < 0) {
1052                 err("usb_register failed for the "__FILE__" driver. Error number %d", result);
1053                 retval = -1;
1054                 goto exit;
1055         }
1056
1057         printk(KERN_INFO KBUILD_MODNAME ": " DRIVER_VERSION ":"
1058                DRIVER_DESC "\n");
1059
1060 exit:
1061         dbg(2, "%s: leave, return value %d", __func__, retval);
1062
1063         return retval;
1064 }
1065
1066
1067 /**
1068  *      lego_usb_tower_exit
1069  */
1070 static void __exit lego_usb_tower_exit(void)
1071 {
1072         dbg(2, "%s: enter", __func__);
1073
1074         /* deregister this driver with the USB subsystem */
1075         usb_deregister (&tower_driver);
1076
1077         dbg(2, "%s: leave", __func__);
1078 }
1079
1080 module_init (lego_usb_tower_init);
1081 module_exit (lego_usb_tower_exit);
1082
1083 MODULE_AUTHOR(DRIVER_AUTHOR);
1084 MODULE_DESCRIPTION(DRIVER_DESC);
1085 #ifdef MODULE_LICENSE
1086 MODULE_LICENSE("GPL");
1087 #endif