drivers/staging/unisys/visorbus/visorchannel.c

   1 /* visorchannel_funcs.c
   2  *
   3  * Copyright (C) 2010 - 2015 UNISYS CORPORATION
   4  * All rights reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms and conditions of the GNU General Public License,
   8  * version 2, as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  13  * NON INFRINGEMENT.  See the GNU General Public License for more
  14  * details.
  15  */
  16
  17 /*
  18  *  This provides Supervisor channel communication primitives, which are
  19  *  independent of the mechanism used to access the channel data.
  20  */
  21
  22 #include <linux/uuid.h>
  23
  24 #include "version.h"
  25 #include "visorbus.h"
  26 #include "controlvmchannel.h"
  27
  28 #define MYDRVNAME "visorchannel"
  29
  30 #define SPAR_CONSOLEVIDEO_CHANNEL_PROTOCOL_GUID \
  31         UUID_LE(0x3cd6e705, 0xd6a2, 0x4aa5,           \
  32                 0xad, 0x5c, 0x7b, 0x8, 0x88, 0x9d, 0xff, 0xe2)
  33 static const uuid_le spar_video_guid = SPAR_CONSOLEVIDEO_CHANNEL_PROTOCOL_GUID;
  34
  35 struct visorchannel {
  36         u64 physaddr;
  37         ulong nbytes;
  38         void __iomem *mapped;
  39         bool requested;
  40         struct channel_header chan_hdr;
  41         uuid_le guid;
  42         ulong size;
  43         bool needs_lock;        /* channel creator knows if more than one
  44                                  * thread will be inserting or removing */
  45         spinlock_t insert_lock; /* protect head writes in chan_hdr */
  46         spinlock_t remove_lock; /* protect tail writes in chan_hdr */
  47
  48         struct {
  49                 struct signal_queue_header req_queue;
  50                 struct signal_queue_header rsp_queue;
  51                 struct signal_queue_header event_queue;
  52                 struct signal_queue_header ack_queue;
  53         } safe_uis_queue;
  54         uuid_le type;
  55         uuid_le inst;
  56 };
  57
  58 /* Creates the struct visorchannel abstraction for a data area in memory,
  59  * but does NOT modify this data area.
  60  */
  61 static struct visorchannel *
  62 visorchannel_create_guts(u64 physaddr, unsigned long channel_bytes,
  63                          gfp_t gfp, unsigned long off,
  64                          uuid_le guid, bool needs_lock)
  65 {
  66         struct visorchannel *channel;
  67         int err;
  68         size_t size = sizeof(struct channel_header);
  69
  70         if (physaddr == 0)
  71                 return NULL;
  72
  73         channel = kzalloc(sizeof(*channel), gfp);
  74         if (!channel)
  75                 goto cleanup;
  76
  77         channel->needs_lock = needs_lock;
  78         spin_lock_init(&channel->insert_lock);
  79         spin_lock_init(&channel->remove_lock);
  80
  81         /* Video driver constains the efi framebuffer so it will get a
  82          * conflict resource when requesting its full mem region. Since
  83          * we are only using the efi framebuffer for video we can ignore
  84          * this. Remember that we haven't requested it so we don't try to
  85          * release later on.
  86          */
  87         channel->requested = request_mem_region(physaddr, size, MYDRVNAME);
  88         if (!channel->requested) {
  89                 if (uuid_le_cmp(guid, spar_video_guid)) {
  90                         /* Not the video channel we care about this */
  91                         goto cleanup;
  92                 }
  93         }
  94
  95         channel->mapped = ioremap_cache(physaddr, size);
  96         if (!channel->mapped) {
  97                 release_mem_region(physaddr, size);
  98                 goto cleanup;
  99         }
 100
 101         channel->physaddr = physaddr;
 102         channel->nbytes = size;
 103
 104         err = visorchannel_read(channel, 0, &channel->chan_hdr,
 105                                 sizeof(struct channel_header));
 106         if (err)
 107                 goto cleanup;
 108
 109         /* we had better be a CLIENT of this channel */
 110         if (channel_bytes == 0)
 111                 channel_bytes = (ulong)channel->chan_hdr.size;
 112         if (uuid_le_cmp(guid, NULL_UUID_LE) == 0)
 113                 guid = channel->chan_hdr.chtype;
 114
 115         iounmap(channel->mapped);
 116         if (channel->requested)
 117                 release_mem_region(channel->physaddr, channel->nbytes);
 118         channel->mapped = NULL;
 119         channel->requested = request_mem_region(channel->physaddr,
 120                                                 channel_bytes, MYDRVNAME);
 121         if (!channel->requested) {
 122                 if (uuid_le_cmp(guid, spar_video_guid)) {
 123                         /* Different we care about this */
 124                         goto cleanup;
 125                 }
 126         }
 127
 128         channel->mapped = ioremap_cache(channel->physaddr, channel_bytes);
 129         if (!channel->mapped) {
 130                 release_mem_region(channel->physaddr, channel_bytes);
 131                 goto cleanup;
 132         }
 133
 134         channel->nbytes = channel_bytes;
 135
 136         channel->size = channel_bytes;
 137         channel->guid = guid;
 138         return channel;
 139
 140 cleanup:
 141         visorchannel_destroy(channel);
 142         return NULL;
 143 }
 144
 145 struct visorchannel *
 146 visorchannel_create(u64 physaddr, unsigned long channel_bytes,
 147                     gfp_t gfp, uuid_le guid)
 148 {
 149         return visorchannel_create_guts(physaddr, channel_bytes, gfp, 0, guid,
 150                                         false);
 151 }
 152 EXPORT_SYMBOL_GPL(visorchannel_create);
 153
 154 struct visorchannel *
 155 visorchannel_create_with_lock(u64 physaddr, unsigned long channel_bytes,
 156                               gfp_t gfp, uuid_le guid)
 157 {
 158         return visorchannel_create_guts(physaddr, channel_bytes, gfp, 0, guid,
 159                                         true);
 160 }
 161 EXPORT_SYMBOL_GPL(visorchannel_create_with_lock);
 162
 163 void
 164 visorchannel_destroy(struct visorchannel *channel)
 165 {
 166         if (!channel)
 167                 return;
 168         if (channel->mapped) {
 169                 iounmap(channel->mapped);
 170                 if (channel->requested)
 171                         release_mem_region(channel->physaddr, channel->nbytes);
 172         }
 173         kfree(channel);
 174 }
 175 EXPORT_SYMBOL_GPL(visorchannel_destroy);
 176
 177 u64
 178 visorchannel_get_physaddr(struct visorchannel *channel)
 179 {
 180         return channel->physaddr;
 181 }
 182 EXPORT_SYMBOL_GPL(visorchannel_get_physaddr);
 183
 184 ulong
 185 visorchannel_get_nbytes(struct visorchannel *channel)
 186 {
 187         return channel->size;
 188 }
 189 EXPORT_SYMBOL_GPL(visorchannel_get_nbytes);
 190
 191 char *
 192 visorchannel_uuid_id(uuid_le *guid, char *s)
 193 {
 194         sprintf(s, "%pUL", guid);
 195         return s;
 196 }
 197 EXPORT_SYMBOL_GPL(visorchannel_uuid_id);
 198
 199 char *
 200 visorchannel_id(struct visorchannel *channel, char *s)
 201 {
 202         return visorchannel_uuid_id(&channel->guid, s);
 203 }
 204 EXPORT_SYMBOL_GPL(visorchannel_id);
 205
 206 char *
 207 visorchannel_zoneid(struct visorchannel *channel, char *s)
 208 {
 209         return visorchannel_uuid_id(&channel->chan_hdr.zone_uuid, s);
 210 }
 211 EXPORT_SYMBOL_GPL(visorchannel_zoneid);
 212
 213 u64
 214 visorchannel_get_clientpartition(struct visorchannel *channel)
 215 {
 216         return channel->chan_hdr.partition_handle;
 217 }
 218 EXPORT_SYMBOL_GPL(visorchannel_get_clientpartition);
 219
 220 int
 221 visorchannel_set_clientpartition(struct visorchannel *channel,
 222                                  u64 partition_handle)
 223 {
 224         channel->chan_hdr.partition_handle = partition_handle;
 225         return 0;
 226 }
 227 EXPORT_SYMBOL_GPL(visorchannel_set_clientpartition);
 228
 229 uuid_le
 230 visorchannel_get_uuid(struct visorchannel *channel)
 231 {
 232         return channel->guid;
 233 }
 234 EXPORT_SYMBOL_GPL(visorchannel_get_uuid);
 235
 236 int
 237 visorchannel_read(struct visorchannel *channel, ulong offset,
 238                   void *local, ulong nbytes)
 239 {
 240         if (offset + nbytes > channel->nbytes)
 241                 return -EIO;
 242
 243         memcpy_fromio(local, channel->mapped + offset, nbytes);
 244
 245         return 0;
 246 }
 247 EXPORT_SYMBOL_GPL(visorchannel_read);
 248
 249 int
 250 visorchannel_write(struct visorchannel *channel, ulong offset,
 251                    void *local, ulong nbytes)
 252 {
 253         size_t chdr_size = sizeof(struct channel_header);
 254         size_t copy_size;
 255
 256         if (offset + nbytes > channel->nbytes)
 257                 return -EIO;
 258
 259         if (offset < chdr_size) {
 260                 copy_size = min(chdr_size - offset, nbytes);
 261                 memcpy(((char *)(&channel->chan_hdr)) + offset,
 262                        local, copy_size);
 263         }
 264
 265         memcpy_toio(channel->mapped + offset, local, nbytes);
 266
 267         return 0;
 268 }
 269 EXPORT_SYMBOL_GPL(visorchannel_write);
 270
 271 int
 272 visorchannel_clear(struct visorchannel *channel, ulong offset, u8 ch,
 273                    ulong nbytes)
 274 {
 275         int err;
 276         int bufsize = PAGE_SIZE;
 277         int written = 0;
 278         u8 *buf;
 279
 280         buf = (u8 *) __get_free_page(GFP_KERNEL);
 281         if (!buf)
 282                 return -ENOMEM;
 283
 284         memset(buf, ch, bufsize);
 285
 286         while (nbytes > 0) {
 287                 int thisbytes = bufsize;
 288
 289                 if (nbytes < thisbytes)
 290                         thisbytes = nbytes;
 291                 err = visorchannel_write(channel, offset + written,
 292                                          buf, thisbytes);
 293                 if (err)
 294                         goto cleanup;
 295
 296                 written += thisbytes;
 297                 nbytes -= thisbytes;
 298         }
 299         err = 0;
 300
 301 cleanup:
 302         free_page((unsigned long) buf);
 303         return err;
 304 }
 305 EXPORT_SYMBOL_GPL(visorchannel_clear);
 306
 307 void __iomem  *
 308 visorchannel_get_header(struct visorchannel *channel)
 309 {
 310         return (void __iomem *)&channel->chan_hdr;
 311 }
 312 EXPORT_SYMBOL_GPL(visorchannel_get_header);
 313
 314 /** Return offset of a specific SIGNAL_QUEUE_HEADER from the beginning of a
 315  *  channel header
 316  */
 317 #define SIG_QUEUE_OFFSET(chan_hdr, q) \
 318         ((chan_hdr)->ch_space_offset + \
 319          ((q) * sizeof(struct signal_queue_header)))
 320
 321 /** Return offset of a specific queue entry (data) from the beginning of a
 322  *  channel header
 323  */
 324 #define SIG_DATA_OFFSET(chan_hdr, q, sig_hdr, slot) \
 325         (SIG_QUEUE_OFFSET(chan_hdr, q) + (sig_hdr)->sig_base_offset + \
 326             ((slot) * (sig_hdr)->signal_size))
 327
 328 /** Write the contents of a specific field within a SIGNAL_QUEUE_HEADER back
 329  *  into host memory
 330  */
 331 #define SIG_WRITE_FIELD(channel, queue, sig_hdr, FIELD)                  \
 332         (visorchannel_write(channel,                                     \
 333                             SIG_QUEUE_OFFSET(&channel->chan_hdr, queue)+ \
 334                             offsetof(struct signal_queue_header, FIELD), \
 335                             &((sig_hdr)->FIELD),                         \
 336                             sizeof((sig_hdr)->FIELD)) >= 0)
 337
 338 static bool
 339 sig_read_header(struct visorchannel *channel, u32 queue,
 340                 struct signal_queue_header *sig_hdr)
 341 {
 342         int err;
 343
 344         if (channel->chan_hdr.ch_space_offset < sizeof(struct channel_header))
 345                 return false;
 346
 347         /* Read the appropriate SIGNAL_QUEUE_HEADER into local memory. */
 348         err = visorchannel_read(channel,
 349                                 SIG_QUEUE_OFFSET(&channel->chan_hdr, queue),
 350                                 sig_hdr, sizeof(struct signal_queue_header));
 351         if (err)
 352                 return false;
 353
 354         return true;
 355 }
 356
 357 static inline bool
 358 sig_read_data(struct visorchannel *channel, u32 queue,
 359               struct signal_queue_header *sig_hdr, u32 slot, void *data)
 360 {
 361         int err;
 362         int signal_data_offset = SIG_DATA_OFFSET(&channel->chan_hdr, queue,
 363                                                  sig_hdr, slot);
 364
 365         err = visorchannel_read(channel, signal_data_offset,
 366                                 data, sig_hdr->signal_size);
 367         if (err)
 368                 return false;
 369
 370         return true;
 371 }
 372
 373 static inline bool
 374 sig_write_data(struct visorchannel *channel, u32 queue,
 375                struct signal_queue_header *sig_hdr, u32 slot, void *data)
 376 {
 377         int err;
 378         int signal_data_offset = SIG_DATA_OFFSET(&channel->chan_hdr, queue,
 379                                                  sig_hdr, slot);
 380
 381         err = visorchannel_write(channel, signal_data_offset,
 382                                  data, sig_hdr->signal_size);
 383         if (err)
 384                 return false;
 385
 386         return true;
 387 }
 388
 389 static bool
 390 signalremove_inner(struct visorchannel *channel, u32 queue, void *msg)
 391 {
 392         struct signal_queue_header sig_hdr;
 393
 394         if (!sig_read_header(channel, queue, &sig_hdr))
 395                 return false;
 396         if (sig_hdr.head == sig_hdr.tail)
 397                 return false;   /* no signals to remove */
 398
 399         sig_hdr.tail = (sig_hdr.tail + 1) % sig_hdr.max_slots;
 400         if (!sig_read_data(channel, queue, &sig_hdr, sig_hdr.tail, msg))
 401                 return false;
 402         sig_hdr.num_received++;
 403
 404         /* For each data field in SIGNAL_QUEUE_HEADER that was modified,
 405          * update host memory.
 406          */
 407         mb(); /* required for channel synch */
 408         if (!SIG_WRITE_FIELD(channel, queue, &sig_hdr, tail))
 409                 return false;
 410         if (!SIG_WRITE_FIELD(channel, queue, &sig_hdr, num_received))
 411                 return false;
 412         return true;
 413 }
 414
 415 bool
 416 visorchannel_signalremove(struct visorchannel *channel, u32 queue, void *msg)
 417 {
 418         bool rc;
 419         unsigned long flags;
 420
 421         if (channel->needs_lock) {
 422                 spin_lock_irqsave(&channel->remove_lock, flags);
 423                 rc = signalremove_inner(channel, queue, msg);
 424                 spin_unlock_irqrestore(&channel->remove_lock, flags);
 425         } else {
 426                 rc = signalremove_inner(channel, queue, msg);
 427         }
 428
 429         return rc;
 430 }
 431 EXPORT_SYMBOL_GPL(visorchannel_signalremove);
 432
 433 bool
 434 visorchannel_signalempty(struct visorchannel *channel, u32 queue)
 435 {
 436         unsigned long flags = 0;
 437         struct signal_queue_header sig_hdr;
 438         bool rc = false;
 439
 440         if (channel->needs_lock)
 441                 spin_lock_irqsave(&channel->remove_lock, flags);
 442
 443         if (!sig_read_header(channel, queue, &sig_hdr))
 444                 rc = true;
 445         if (sig_hdr.head == sig_hdr.tail)
 446                 rc = true;
 447         if (channel->needs_lock)
 448                 spin_unlock_irqrestore(&channel->remove_lock, flags);
 449
 450         return rc;
 451 }
 452 EXPORT_SYMBOL_GPL(visorchannel_signalempty);
 453
 454 static bool
 455 signalinsert_inner(struct visorchannel *channel, u32 queue, void *msg)
 456 {
 457         struct signal_queue_header sig_hdr;
 458
 459         if (!sig_read_header(channel, queue, &sig_hdr))
 460                 return false;
 461
 462         sig_hdr.head = ((sig_hdr.head + 1) % sig_hdr.max_slots);
 463         if (sig_hdr.head == sig_hdr.tail) {
 464                 sig_hdr.num_overflows++;
 465                 visorchannel_write(channel,
 466                                    SIG_QUEUE_OFFSET(&channel->chan_hdr, queue) +
 467                                    offsetof(struct signal_queue_header,
 468                                             num_overflows),
 469                                    &(sig_hdr.num_overflows),
 470                                    sizeof(sig_hdr.num_overflows));
 471                 return false;
 472         }
 473
 474         if (!sig_write_data(channel, queue, &sig_hdr, sig_hdr.head, msg))
 475                 return false;
 476
 477         sig_hdr.num_sent++;
 478
 479         /* For each data field in SIGNAL_QUEUE_HEADER that was modified,
 480          * update host memory.
 481          */
 482         mb(); /* required for channel synch */
 483         if (!SIG_WRITE_FIELD(channel, queue, &sig_hdr, head))
 484                 return false;
 485         if (!SIG_WRITE_FIELD(channel, queue, &sig_hdr, num_sent))
 486                 return false;
 487
 488         return true;
 489 }
 490
 491 bool
 492 visorchannel_signalinsert(struct visorchannel *channel, u32 queue, void *msg)
 493 {
 494         bool rc;
 495         unsigned long flags;
 496
 497         if (channel->needs_lock) {
 498                 spin_lock_irqsave(&channel->insert_lock, flags);
 499                 rc = signalinsert_inner(channel, queue, msg);
 500                 spin_unlock_irqrestore(&channel->insert_lock, flags);
 501         } else {
 502                 rc = signalinsert_inner(channel, queue, msg);
 503         }
 504
 505         return rc;
 506 }
 507 EXPORT_SYMBOL_GPL(visorchannel_signalinsert);
 508
 509 int
 510 visorchannel_signalqueue_slots_avail(struct visorchannel *channel, u32 queue)
 511 {
 512         struct signal_queue_header sig_hdr;
 513         u32 slots_avail, slots_used;
 514         u32 head, tail;
 515
 516         if (!sig_read_header(channel, queue, &sig_hdr))
 517                 return 0;
 518         head = sig_hdr.head;
 519         tail = sig_hdr.tail;
 520         if (head < tail)
 521                 head = head + sig_hdr.max_slots;
 522         slots_used = (head - tail);
 523         slots_avail = sig_hdr.max_signals - slots_used;
 524         return (int)slots_avail;
 525 }
 526 EXPORT_SYMBOL_GPL(visorchannel_signalqueue_slots_avail);
 527
 528 int
 529 visorchannel_signalqueue_max_slots(struct visorchannel *channel, u32 queue)
 530 {
 531         struct signal_queue_header sig_hdr;
 532
 533         if (!sig_read_header(channel, queue, &sig_hdr))
 534                 return 0;
 535         return (int)sig_hdr.max_signals;
 536 }
 537 EXPORT_SYMBOL_GPL(visorchannel_signalqueue_max_slots);
 538
 539 static void
 540 sigqueue_debug(struct signal_queue_header *q, int which, struct seq_file *seq)
 541 {
 542         seq_printf(seq, "Signal Queue #%d\n", which);
 543         seq_printf(seq, "   VersionId          = %lu\n", (ulong)q->version);
 544         seq_printf(seq, "   Type               = %lu\n", (ulong)q->chtype);
 545         seq_printf(seq, "   oSignalBase        = %llu\n",
 546                    (long long)q->sig_base_offset);
 547         seq_printf(seq, "   SignalSize         = %lu\n", (ulong)q->signal_size);
 548         seq_printf(seq, "   MaxSignalSlots     = %lu\n",
 549                    (ulong)q->max_slots);
 550         seq_printf(seq, "   MaxSignals         = %lu\n", (ulong)q->max_signals);
 551         seq_printf(seq, "   FeatureFlags       = %-16.16Lx\n",
 552                    (long long)q->features);
 553         seq_printf(seq, "   NumSignalsSent     = %llu\n",
 554                    (long long)q->num_sent);
 555         seq_printf(seq, "   NumSignalsReceived = %llu\n",
 556                    (long long)q->num_received);
 557         seq_printf(seq, "   NumOverflows       = %llu\n",
 558                    (long long)q->num_overflows);
 559         seq_printf(seq, "   Head               = %lu\n", (ulong)q->head);
 560         seq_printf(seq, "   Tail               = %lu\n", (ulong)q->tail);
 561 }
 562
 563 void
 564 visorchannel_debug(struct visorchannel *channel, int num_queues,
 565                    struct seq_file *seq, u32 off)
 566 {
 567         u64 addr = 0;
 568         ulong nbytes = 0, nbytes_region = 0;
 569         struct channel_header hdr;
 570         struct channel_header *phdr = &hdr;
 571         int i = 0;
 572         int errcode = 0;
 573
 574         if (!channel)
 575                 return;
 576
 577         addr = visorchannel_get_physaddr(channel);
 578         nbytes_region = visorchannel_get_nbytes(channel);
 579         errcode = visorchannel_read(channel, off,
 580                                     phdr, sizeof(struct channel_header));
 581         if (errcode < 0) {
 582                 seq_printf(seq,
 583                            "Read of channel header failed with errcode=%d)\n",
 584                            errcode);
 585                 if (off == 0) {
 586                         phdr = &channel->chan_hdr;
 587                         seq_puts(seq, "(following data may be stale)\n");
 588                 } else {
 589                         return;
 590                 }
 591         }
 592         nbytes = (ulong)(phdr->size);
 593         seq_printf(seq, "--- Begin channel @0x%-16.16Lx for 0x%lx bytes (region=0x%lx bytes) ---\n",
 594                    addr + off, nbytes, nbytes_region);
 595         seq_printf(seq, "Type            = %pUL\n", &phdr->chtype);
 596         seq_printf(seq, "ZoneGuid        = %pUL\n", &phdr->zone_uuid);
 597         seq_printf(seq, "Signature       = 0x%-16.16Lx\n",
 598                    (long long)phdr->signature);
 599         seq_printf(seq, "LegacyState     = %lu\n", (ulong)phdr->legacy_state);
 600         seq_printf(seq, "SrvState        = %lu\n", (ulong)phdr->srv_state);
 601         seq_printf(seq, "CliStateBoot    = %lu\n", (ulong)phdr->cli_state_boot);
 602         seq_printf(seq, "CliStateOS      = %lu\n", (ulong)phdr->cli_state_os);
 603         seq_printf(seq, "HeaderSize      = %lu\n", (ulong)phdr->header_size);
 604         seq_printf(seq, "Size            = %llu\n", (long long)phdr->size);
 605         seq_printf(seq, "Features        = 0x%-16.16llx\n",
 606                    (long long)phdr->features);
 607         seq_printf(seq, "PartitionHandle = 0x%-16.16llx\n",
 608                    (long long)phdr->partition_handle);
 609         seq_printf(seq, "Handle          = 0x%-16.16llx\n",
 610                    (long long)phdr->handle);
 611         seq_printf(seq, "VersionId       = %lu\n", (ulong)phdr->version_id);
 612         seq_printf(seq, "oChannelSpace   = %llu\n",
 613                    (long long)phdr->ch_space_offset);
 614         if ((phdr->ch_space_offset == 0) || (errcode < 0))
 615                 ;
 616         else
 617                 for (i = 0; i < num_queues; i++) {
 618                         struct signal_queue_header q;
 619
 620                         errcode = visorchannel_read(channel,
 621                                                     off +
 622                                                     phdr->ch_space_offset +
 623                                                     (i * sizeof(q)),
 624                                                     &q, sizeof(q));
 625                         if (errcode < 0) {
 626                                 seq_printf(seq,
 627                                            "failed to read signal queue #%d from channel @0x%-16.16Lx errcode=%d\n",
 628                                            i, addr, errcode);
 629                                 continue;
 630                         }
 631                         sigqueue_debug(&q, i, seq);
 632                 }
 633         seq_printf(seq, "--- End   channel @0x%-16.16Lx for 0x%lx bytes ---\n",
 634                    addr + off, nbytes);
 635 }
 636 EXPORT_SYMBOL_GPL(visorchannel_debug);