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
 189 #define LEGO_USB_TOWER_MINOR_BASE       160
 190
 191
 192 /* Structure to hold all of our device specific stuff */
 193 struct lego_usb_tower {
 194         struct mutex            lock;           /* locks this structure */
 195         struct usb_device*      udev;           /* save off the usb device pointer */
 196         unsigned char           minor;          /* the starting minor number for this device */
 197
 198         int                     open_count;     /* number of times this port has been opened */
 199         unsigned long           disconnected:1;
 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         /* free data structures */
 300         usb_free_urb(dev->interrupt_in_urb);
 301         usb_free_urb(dev->interrupt_out_urb);
 302         kfree (dev->read_buffer);
 303         kfree (dev->interrupt_in_buffer);
 304         kfree (dev->interrupt_out_buffer);
 305         usb_put_dev(dev->udev);
 306         kfree (dev);
 307 }
 308
 309
 310 /**
 311  *      tower_open
 312  */
 313 static int tower_open (struct inode *inode, struct file *file)
 314 {
 315         struct lego_usb_tower *dev = NULL;
 316         int subminor;
 317         int retval = 0;
 318         struct usb_interface *interface;
 319         struct tower_reset_reply *reset_reply;
 320         int result;
 321
 322         reset_reply = kmalloc(sizeof(*reset_reply), GFP_KERNEL);
 323
 324         if (!reset_reply) {
 325                 retval = -ENOMEM;
 326                 goto exit;
 327         }
 328
 329         nonseekable_open(inode, file);
 330         subminor = iminor(inode);
 331
 332         interface = usb_find_interface (&tower_driver, subminor);
 333
 334         if (!interface) {
 335                 pr_err("error, can't find device for minor %d\n", subminor);
 336                 retval = -ENODEV;
 337                 goto exit;
 338         }
 339
 340         dev = usb_get_intfdata(interface);
 341         if (!dev) {
 342                 retval = -ENODEV;
 343                 goto exit;
 344         }
 345
 346         /* lock this device */
 347         if (mutex_lock_interruptible(&dev->lock)) {
 348                 retval = -ERESTARTSYS;
 349                 goto exit;
 350         }
 351
 352
 353         /* allow opening only once */
 354         if (dev->open_count) {
 355                 retval = -EBUSY;
 356                 goto unlock_exit;
 357         }
 358
 359         /* reset the tower */
 360         result = usb_control_msg (dev->udev,
 361                                   usb_rcvctrlpipe(dev->udev, 0),
 362                                   LEGO_USB_TOWER_REQUEST_RESET,
 363                                   USB_TYPE_VENDOR | USB_DIR_IN | USB_RECIP_DEVICE,
 364                                   0,
 365                                   0,
 366                                   reset_reply,
 367                                   sizeof(*reset_reply),
 368                                   1000);
 369         if (result < 0) {
 370                 dev_err(&dev->udev->dev,
 371                         "LEGO USB Tower reset control request failed\n");
 372                 retval = result;
 373                 goto unlock_exit;
 374         }
 375
 376         /* initialize in direction */
 377         dev->read_buffer_length = 0;
 378         dev->read_packet_length = 0;
 379         usb_fill_int_urb (dev->interrupt_in_urb,
 380                           dev->udev,
 381                           usb_rcvintpipe(dev->udev, dev->interrupt_in_endpoint->bEndpointAddress),
 382                           dev->interrupt_in_buffer,
 383                           usb_endpoint_maxp(dev->interrupt_in_endpoint),
 384                           tower_interrupt_in_callback,
 385                           dev,
 386                           dev->interrupt_in_interval);
 387
 388         dev->interrupt_in_running = 1;
 389         dev->interrupt_in_done = 0;
 390         mb();
 391
 392         retval = usb_submit_urb (dev->interrupt_in_urb, GFP_KERNEL);
 393         if (retval) {
 394                 dev_err(&dev->udev->dev,
 395                         "Couldn't submit interrupt_in_urb %d\n", retval);
 396                 dev->interrupt_in_running = 0;
 397                 goto unlock_exit;
 398         }
 399
 400         /* save device in the file's private structure */
 401         file->private_data = dev;
 402
 403         dev->open_count = 1;
 404
 405 unlock_exit:
 406         mutex_unlock(&dev->lock);
 407
 408 exit:
 409         kfree(reset_reply);
 410         return retval;
 411 }
 412
 413 /**
 414  *      tower_release
 415  */
 416 static int tower_release (struct inode *inode, struct file *file)
 417 {
 418         struct lego_usb_tower *dev;
 419         int retval = 0;
 420
 421         dev = file->private_data;
 422
 423         if (dev == NULL) {
 424                 retval = -ENODEV;
 425                 goto exit;
 426         }
 427
 428         mutex_lock(&dev->lock);
 429
 430         if (dev->open_count != 1) {
 431                 dev_dbg(&dev->udev->dev, "%s: device not opened exactly once\n",
 432                         __func__);
 433                 retval = -ENODEV;
 434                 goto unlock_exit;
 435         }
 436
 437         if (dev->disconnected) {
 438                 /* the device was unplugged before the file was released */
 439
 440                 /* unlock here as tower_delete frees dev */
 441                 mutex_unlock(&dev->lock);
 442                 tower_delete (dev);
 443                 goto exit;
 444         }
 445
 446         /* wait until write transfer is finished */
 447         if (dev->interrupt_out_busy) {
 448                 wait_event_interruptible_timeout (dev->write_wait, !dev->interrupt_out_busy, 2 * HZ);
 449         }
 450         tower_abort_transfers (dev);
 451         dev->open_count = 0;
 452
 453 unlock_exit:
 454         mutex_unlock(&dev->lock);
 455 exit:
 456         return retval;
 457 }
 458
 459
 460 /**
 461  *      tower_abort_transfers
 462  *      aborts transfers and frees associated data structures
 463  */
 464 static void tower_abort_transfers (struct lego_usb_tower *dev)
 465 {
 466         if (dev == NULL)
 467                 return;
 468
 469         /* shutdown transfer */
 470         if (dev->interrupt_in_running) {
 471                 dev->interrupt_in_running = 0;
 472                 mb();
 473                 usb_kill_urb(dev->interrupt_in_urb);
 474         }
 475         if (dev->interrupt_out_busy)
 476                 usb_kill_urb(dev->interrupt_out_urb);
 477 }
 478
 479
 480 /**
 481  *      tower_check_for_read_packet
 482  *
 483  *      To get correct semantics for signals and non-blocking I/O
 484  *      with packetizing we pretend not to see any data in the read buffer
 485  *      until it has been there unchanged for at least
 486  *      dev->packet_timeout_jiffies, or until the buffer is full.
 487  */
 488 static void tower_check_for_read_packet (struct lego_usb_tower *dev)
 489 {
 490         spin_lock_irq (&dev->read_buffer_lock);
 491         if (!packet_timeout
 492             || time_after(jiffies, dev->read_last_arrival + dev->packet_timeout_jiffies)
 493             || dev->read_buffer_length == read_buffer_size) {
 494                 dev->read_packet_length = dev->read_buffer_length;
 495         }
 496         dev->interrupt_in_done = 0;
 497         spin_unlock_irq (&dev->read_buffer_lock);
 498 }
 499
 500
 501 /**
 502  *      tower_poll
 503  */
 504 static unsigned int tower_poll (struct file *file, poll_table *wait)
 505 {
 506         struct lego_usb_tower *dev;
 507         unsigned int mask = 0;
 508
 509         dev = file->private_data;
 510
 511         if (dev->disconnected)
 512                 return POLLERR | POLLHUP;
 513
 514         poll_wait(file, &dev->read_wait, wait);
 515         poll_wait(file, &dev->write_wait, wait);
 516
 517         tower_check_for_read_packet(dev);
 518         if (dev->read_packet_length > 0) {
 519                 mask |= POLLIN | POLLRDNORM;
 520         }
 521         if (!dev->interrupt_out_busy) {
 522                 mask |= POLLOUT | POLLWRNORM;
 523         }
 524
 525         return mask;
 526 }
 527
 528
 529 /**
 530  *      tower_llseek
 531  */
 532 static loff_t tower_llseek (struct file *file, loff_t off, int whence)
 533 {
 534         return -ESPIPE;         /* unseekable */
 535 }
 536
 537
 538 /**
 539  *      tower_read
 540  */
 541 static ssize_t tower_read (struct file *file, char __user *buffer, size_t count, loff_t *ppos)
 542 {
 543         struct lego_usb_tower *dev;
 544         size_t bytes_to_read;
 545         int i;
 546         int retval = 0;
 547         unsigned long timeout = 0;
 548
 549         dev = file->private_data;
 550
 551         /* lock this object */
 552         if (mutex_lock_interruptible(&dev->lock)) {
 553                 retval = -ERESTARTSYS;
 554                 goto exit;
 555         }
 556
 557         /* verify that the device wasn't unplugged */
 558         if (dev->disconnected) {
 559                 retval = -ENODEV;
 560                 pr_err("No device or device unplugged %d\n", retval);
 561                 goto unlock_exit;
 562         }
 563
 564         /* verify that we actually have some data to read */
 565         if (count == 0) {
 566                 dev_dbg(&dev->udev->dev, "read request of 0 bytes\n");
 567                 goto unlock_exit;
 568         }
 569
 570         if (read_timeout) {
 571                 timeout = jiffies + msecs_to_jiffies(read_timeout);
 572         }
 573
 574         /* wait for data */
 575         tower_check_for_read_packet (dev);
 576         while (dev->read_packet_length == 0) {
 577                 if (file->f_flags & O_NONBLOCK) {
 578                         retval = -EAGAIN;
 579                         goto unlock_exit;
 580                 }
 581                 retval = wait_event_interruptible_timeout(dev->read_wait, dev->interrupt_in_done, dev->packet_timeout_jiffies);
 582                 if (retval < 0) {
 583                         goto unlock_exit;
 584                 }
 585
 586                 /* reset read timeout during read or write activity */
 587                 if (read_timeout
 588                     && (dev->read_buffer_length || dev->interrupt_out_busy)) {
 589                         timeout = jiffies + msecs_to_jiffies(read_timeout);
 590                 }
 591                 /* check for read timeout */
 592                 if (read_timeout && time_after (jiffies, timeout)) {
 593                         retval = -ETIMEDOUT;
 594                         goto unlock_exit;
 595                 }
 596                 tower_check_for_read_packet (dev);
 597         }
 598
 599         /* copy the data from read_buffer into userspace */
 600         bytes_to_read = min(count, dev->read_packet_length);
 601
 602         if (copy_to_user (buffer, dev->read_buffer, bytes_to_read)) {
 603                 retval = -EFAULT;
 604                 goto unlock_exit;
 605         }
 606
 607         spin_lock_irq (&dev->read_buffer_lock);
 608         dev->read_buffer_length -= bytes_to_read;
 609         dev->read_packet_length -= bytes_to_read;
 610         for (i=0; i<dev->read_buffer_length; i++) {
 611                 dev->read_buffer[i] = dev->read_buffer[i+bytes_to_read];
 612         }
 613         spin_unlock_irq (&dev->read_buffer_lock);
 614
 615         retval = bytes_to_read;
 616
 617 unlock_exit:
 618         /* unlock the device */
 619         mutex_unlock(&dev->lock);
 620
 621 exit:
 622         return retval;
 623 }
 624
 625
 626 /**
 627  *      tower_write
 628  */
 629 static ssize_t tower_write (struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
 630 {
 631         struct lego_usb_tower *dev;
 632         size_t bytes_to_write;
 633         int retval = 0;
 634
 635         dev = file->private_data;
 636
 637         /* lock this object */
 638         if (mutex_lock_interruptible(&dev->lock)) {
 639                 retval = -ERESTARTSYS;
 640                 goto exit;
 641         }
 642
 643         /* verify that the device wasn't unplugged */
 644         if (dev->disconnected) {
 645                 retval = -ENODEV;
 646                 pr_err("No device or device unplugged %d\n", retval);
 647                 goto unlock_exit;
 648         }
 649
 650         /* verify that we actually have some data to write */
 651         if (count == 0) {
 652                 dev_dbg(&dev->udev->dev, "write request of 0 bytes\n");
 653                 goto unlock_exit;
 654         }
 655
 656         /* wait until previous transfer is finished */
 657         while (dev->interrupt_out_busy) {
 658                 if (file->f_flags & O_NONBLOCK) {
 659                         retval = -EAGAIN;
 660                         goto unlock_exit;
 661                 }
 662                 retval = wait_event_interruptible (dev->write_wait, !dev->interrupt_out_busy);
 663                 if (retval) {
 664                         goto unlock_exit;
 665                 }
 666         }
 667
 668         /* write the data into interrupt_out_buffer from userspace */
 669         bytes_to_write = min_t(int, count, write_buffer_size);
 670         dev_dbg(&dev->udev->dev, "%s: count = %Zd, bytes_to_write = %Zd\n",
 671                 __func__, count, bytes_to_write);
 672
 673         if (copy_from_user (dev->interrupt_out_buffer, buffer, bytes_to_write)) {
 674                 retval = -EFAULT;
 675                 goto unlock_exit;
 676         }
 677
 678         /* send off the urb */
 679         usb_fill_int_urb(dev->interrupt_out_urb,
 680                          dev->udev,
 681                          usb_sndintpipe(dev->udev, dev->interrupt_out_endpoint->bEndpointAddress),
 682                          dev->interrupt_out_buffer,
 683                          bytes_to_write,
 684                          tower_interrupt_out_callback,
 685                          dev,
 686                          dev->interrupt_out_interval);
 687
 688         dev->interrupt_out_busy = 1;
 689         wmb();
 690
 691         retval = usb_submit_urb (dev->interrupt_out_urb, GFP_KERNEL);
 692         if (retval) {
 693                 dev->interrupt_out_busy = 0;
 694                 dev_err(&dev->udev->dev,
 695                         "Couldn't submit interrupt_out_urb %d\n", retval);
 696                 goto unlock_exit;
 697         }
 698         retval = bytes_to_write;
 699
 700 unlock_exit:
 701         /* unlock the device */
 702         mutex_unlock(&dev->lock);
 703
 704 exit:
 705         return retval;
 706 }
 707
 708
 709 /**
 710  *      tower_interrupt_in_callback
 711  */
 712 static void tower_interrupt_in_callback (struct urb *urb)
 713 {
 714         struct lego_usb_tower *dev = urb->context;
 715         int status = urb->status;
 716         int retval;
 717
 718         lego_usb_tower_debug_data(&dev->udev->dev, __func__,
 719                                   urb->actual_length, urb->transfer_buffer);
 720
 721         if (status) {
 722                 if (status == -ENOENT ||
 723                     status == -ECONNRESET ||
 724                     status == -ESHUTDOWN) {
 725                         goto exit;
 726                 } else {
 727                         dev_dbg(&dev->udev->dev,
 728                                 "%s: nonzero status received: %d\n", __func__,
 729                                 status);
 730                         goto resubmit; /* maybe we can recover */
 731                 }
 732         }
 733
 734         if (urb->actual_length > 0) {
 735                 spin_lock (&dev->read_buffer_lock);
 736                 if (dev->read_buffer_length + urb->actual_length < read_buffer_size) {
 737                         memcpy (dev->read_buffer + dev->read_buffer_length,
 738                                 dev->interrupt_in_buffer,
 739                                 urb->actual_length);
 740                         dev->read_buffer_length += urb->actual_length;
 741                         dev->read_last_arrival = jiffies;
 742                         dev_dbg(&dev->udev->dev, "%s: received %d bytes\n",
 743                                 __func__, urb->actual_length);
 744                 } else {
 745                         pr_warn("read_buffer overflow, %d bytes dropped\n",
 746                                 urb->actual_length);
 747                 }
 748                 spin_unlock (&dev->read_buffer_lock);
 749         }
 750
 751 resubmit:
 752         /* resubmit if we're still running */
 753         if (dev->interrupt_in_running) {
 754                 retval = usb_submit_urb (dev->interrupt_in_urb, GFP_ATOMIC);
 755                 if (retval)
 756                         dev_err(&dev->udev->dev,
 757                                 "%s: usb_submit_urb failed (%d)\n",
 758                                 __func__, retval);
 759         }
 760
 761 exit:
 762         dev->interrupt_in_done = 1;
 763         wake_up_interruptible (&dev->read_wait);
 764 }
 765
 766
 767 /**
 768  *      tower_interrupt_out_callback
 769  */
 770 static void tower_interrupt_out_callback (struct urb *urb)
 771 {
 772         struct lego_usb_tower *dev = urb->context;
 773         int status = urb->status;
 774
 775         lego_usb_tower_debug_data(&dev->udev->dev, __func__,
 776                                   urb->actual_length, urb->transfer_buffer);
 777
 778         /* sync/async unlink faults aren't errors */
 779         if (status && !(status == -ENOENT ||
 780                         status == -ECONNRESET ||
 781                         status == -ESHUTDOWN)) {
 782                 dev_dbg(&dev->udev->dev,
 783                         "%s: nonzero write bulk status received: %d\n", __func__,
 784                         status);
 785         }
 786
 787         dev->interrupt_out_busy = 0;
 788         wake_up_interruptible(&dev->write_wait);
 789 }
 790
 791
 792 /**
 793  *      tower_probe
 794  *
 795  *      Called by the usb core when a new device is connected that it thinks
 796  *      this driver might be interested in.
 797  */
 798 static int tower_probe (struct usb_interface *interface, const struct usb_device_id *id)
 799 {
 800         struct device *idev = &interface->dev;
 801         struct usb_device *udev = interface_to_usbdev(interface);
 802         struct lego_usb_tower *dev = NULL;
 803         struct usb_host_interface *iface_desc;
 804         struct usb_endpoint_descriptor* endpoint;
 805         struct tower_get_version_reply *get_version_reply = NULL;
 806         int i;
 807         int retval = -ENOMEM;
 808         int result;
 809
 810         /* allocate memory for our device state and initialize it */
 811
 812         dev = kmalloc (sizeof(struct lego_usb_tower), GFP_KERNEL);
 813
 814         if (dev == NULL) {
 815                 dev_err(idev, "Out of memory\n");
 816                 goto exit;
 817         }
 818
 819         mutex_init(&dev->lock);
 820
 821         dev->udev = usb_get_dev(udev);
 822         dev->open_count = 0;
 823         dev->disconnected = 0;
 824
 825         dev->read_buffer = NULL;
 826         dev->read_buffer_length = 0;
 827         dev->read_packet_length = 0;
 828         spin_lock_init (&dev->read_buffer_lock);
 829         dev->packet_timeout_jiffies = msecs_to_jiffies(packet_timeout);
 830         dev->read_last_arrival = jiffies;
 831
 832         init_waitqueue_head (&dev->read_wait);
 833         init_waitqueue_head (&dev->write_wait);
 834
 835         dev->interrupt_in_buffer = NULL;
 836         dev->interrupt_in_endpoint = NULL;
 837         dev->interrupt_in_urb = NULL;
 838         dev->interrupt_in_running = 0;
 839         dev->interrupt_in_done = 0;
 840
 841         dev->interrupt_out_buffer = NULL;
 842         dev->interrupt_out_endpoint = NULL;
 843         dev->interrupt_out_urb = NULL;
 844         dev->interrupt_out_busy = 0;
 845
 846         iface_desc = interface->cur_altsetting;
 847
 848         /* set up the endpoint information */
 849         for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
 850                 endpoint = &iface_desc->endpoint[i].desc;
 851
 852                 if (usb_endpoint_xfer_int(endpoint)) {
 853                         if (usb_endpoint_dir_in(endpoint))
 854                                 dev->interrupt_in_endpoint = endpoint;
 855                         else
 856                                 dev->interrupt_out_endpoint = endpoint;
 857                 }
 858         }
 859         if(dev->interrupt_in_endpoint == NULL) {
 860                 dev_err(idev, "interrupt in endpoint not found\n");
 861                 goto error;
 862         }
 863         if (dev->interrupt_out_endpoint == NULL) {
 864                 dev_err(idev, "interrupt out endpoint not found\n");
 865                 goto error;
 866         }
 867
 868         dev->read_buffer = kmalloc (read_buffer_size, GFP_KERNEL);
 869         if (!dev->read_buffer) {
 870                 dev_err(idev, "Couldn't allocate read_buffer\n");
 871                 goto error;
 872         }
 873         dev->interrupt_in_buffer = kmalloc (usb_endpoint_maxp(dev->interrupt_in_endpoint), GFP_KERNEL);
 874         if (!dev->interrupt_in_buffer) {
 875                 dev_err(idev, "Couldn't allocate interrupt_in_buffer\n");
 876                 goto error;
 877         }
 878         dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
 879         if (!dev->interrupt_in_urb) {
 880                 dev_err(idev, "Couldn't allocate interrupt_in_urb\n");
 881                 goto error;
 882         }
 883         dev->interrupt_out_buffer = kmalloc (write_buffer_size, GFP_KERNEL);
 884         if (!dev->interrupt_out_buffer) {
 885                 dev_err(idev, "Couldn't allocate interrupt_out_buffer\n");
 886                 goto error;
 887         }
 888         dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
 889         if (!dev->interrupt_out_urb) {
 890                 dev_err(idev, "Couldn't allocate interrupt_out_urb\n");
 891                 goto error;
 892         }
 893         dev->interrupt_in_interval = interrupt_in_interval ? interrupt_in_interval : dev->interrupt_in_endpoint->bInterval;
 894         dev->interrupt_out_interval = interrupt_out_interval ? interrupt_out_interval : dev->interrupt_out_endpoint->bInterval;
 895
 896         get_version_reply = kmalloc(sizeof(*get_version_reply), GFP_KERNEL);
 897
 898         if (!get_version_reply) {
 899                 retval = -ENOMEM;
 900                 goto error;
 901         }
 902
 903         /* get the firmware version and log it */
 904         result = usb_control_msg (udev,
 905                                   usb_rcvctrlpipe(udev, 0),
 906                                   LEGO_USB_TOWER_REQUEST_GET_VERSION,
 907                                   USB_TYPE_VENDOR | USB_DIR_IN | USB_RECIP_DEVICE,
 908                                   0,
 909                                   0,
 910                                   get_version_reply,
 911                                   sizeof(*get_version_reply),
 912                                   1000);
 913         if (result != sizeof(*get_version_reply)) {
 914                 if (result >= 0)
 915                         result = -EIO;
 916                 dev_err(idev, "get version request failed: %d\n", result);
 917                 retval = result;
 918                 goto error;
 919         }
 920         dev_info(&interface->dev,
 921                  "LEGO USB Tower firmware version is %d.%d build %d\n",
 922                  get_version_reply->major,
 923                  get_version_reply->minor,
 924                  le16_to_cpu(get_version_reply->build_no));
 925
 926         /* we can register the device now, as it is ready */
 927         usb_set_intfdata (interface, dev);
 928
 929         retval = usb_register_dev (interface, &tower_class);
 930
 931         if (retval) {
 932                 /* something prevented us from registering this driver */
 933                 dev_err(idev, "Not able to get a minor for this device.\n");
 934                 goto error;
 935         }
 936         dev->minor = interface->minor;
 937
 938         /* let the user know what node this device is now attached to */
 939         dev_info(&interface->dev, "LEGO USB Tower #%d now attached to major "
 940                  "%d minor %d\n", (dev->minor - LEGO_USB_TOWER_MINOR_BASE),
 941                  USB_MAJOR, dev->minor);
 942
 943 exit:
 944         kfree(get_version_reply);
 945         return retval;
 946
 947 error:
 948         kfree(get_version_reply);
 949         tower_delete(dev);
 950         return retval;
 951 }
 952
 953
 954 /**
 955  *      tower_disconnect
 956  *
 957  *      Called by the usb core when the device is removed from the system.
 958  */
 959 static void tower_disconnect (struct usb_interface *interface)
 960 {
 961         struct lego_usb_tower *dev;
 962         int minor;
 963
 964         dev = usb_get_intfdata (interface);
 965
 966         minor = dev->minor;
 967
 968         /* give back our minor and prevent further open() */
 969         usb_deregister_dev (interface, &tower_class);
 970
 971         /* stop I/O */
 972         usb_poison_urb(dev->interrupt_in_urb);
 973         usb_poison_urb(dev->interrupt_out_urb);
 974
 975         mutex_lock(&dev->lock);
 976
 977         /* if the device is not opened, then we clean up right now */
 978         if (!dev->open_count) {
 979                 mutex_unlock(&dev->lock);
 980                 tower_delete (dev);
 981         } else {
 982                 dev->disconnected = 1;
 983                 /* wake up pollers */
 984                 wake_up_interruptible_all(&dev->read_wait);
 985                 wake_up_interruptible_all(&dev->write_wait);
 986                 mutex_unlock(&dev->lock);
 987         }
 988
 989         dev_info(&interface->dev, "LEGO USB Tower #%d now disconnected\n",
 990                  (minor - LEGO_USB_TOWER_MINOR_BASE));
 991 }
 992
 993 module_usb_driver(tower_driver);
 994
 995 MODULE_AUTHOR(DRIVER_AUTHOR);
 996 MODULE_DESCRIPTION(DRIVER_DESC);
 997 #ifdef MODULE_LICENSE
 998 MODULE_LICENSE("GPL");
 999 #endif