arch/powerpc/platforms/iseries/viopath.c

   1 /* -*- linux-c -*-
   2  *
   3  *  iSeries Virtual I/O Message Path code
   4  *
   5  *  Authors: Dave Boutcher <boutcher@us.ibm.com>
   6  *           Ryan Arnold <ryanarn@us.ibm.com>
   7  *           Colin Devilbiss <devilbis@us.ibm.com>
   8  *
   9  * (C) Copyright 2000-2005 IBM Corporation
  10  *
  11  * This code is used by the iSeries virtual disk, cd,
  12  * tape, and console to communicate with OS/400 in another
  13  * partition.
  14  *
  15  * This program is free software;  you can redistribute it and/or
  16  * modify it under the terms of the GNU General Public License as
  17  * published by the Free Software Foundation; either version 2 of the
  18  * License, or (at your option) anyu later version.
  19  *
  20  * This program is distributed in the hope that it will be useful, but
  21  * WITHOUT ANY WARRANTY; without even the implied warranty of
  22  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  23  * General Public License for more details.
  24  *
  25  * You should have received a copy of the GNU General Public License
  26  * along with this program; if not, write to the Free Software Foundation,
  27  * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  28  *
  29  */
  30 #include <linux/module.h>
  31 #include <linux/kernel.h>
  32 #include <linux/errno.h>
  33 #include <linux/vmalloc.h>
  34 #include <linux/string.h>
  35 #include <linux/proc_fs.h>
  36 #include <linux/dma-mapping.h>
  37 #include <linux/wait.h>
  38 #include <linux/seq_file.h>
  39 #include <linux/smp_lock.h>
  40 #include <linux/interrupt.h>
  41
  42 #include <asm/system.h>
  43 #include <asm/uaccess.h>
  44 #include <asm/prom.h>
  45 #include <asm/firmware.h>
  46 #include <asm/iseries/hv_types.h>
  47 #include <asm/iseries/hv_lp_event.h>
  48 #include <asm/iseries/hv_lp_config.h>
  49 #include <asm/iseries/mf.h>
  50 #include <asm/iseries/vio.h>
  51
  52 /* Status of the path to each other partition in the system.
  53  * This is overkill, since we will only ever establish connections
  54  * to our hosting partition and the primary partition on the system.
  55  * But this allows for other support in the future.
  56  */
  57 static struct viopathStatus {
  58         int isOpen;             /* Did we open the path?            */
  59         int isActive;           /* Do we have a mon msg outstanding */
  60         int users[VIO_MAX_SUBTYPES];
  61         HvLpInstanceId mSourceInst;
  62         HvLpInstanceId mTargetInst;
  63         int numberAllocated;
  64 } viopathStatus[HVMAXARCHITECTEDLPS];
  65
  66 static DEFINE_SPINLOCK(statuslock);
  67
  68 /*
  69  * For each kind of event we allocate a buffer that is
  70  * guaranteed not to cross a page boundary
  71  */
  72 static unsigned char event_buffer[VIO_MAX_SUBTYPES * 256]
  73         __attribute__((__aligned__(4096)));
  74 static atomic_t event_buffer_available[VIO_MAX_SUBTYPES];
  75 static int event_buffer_initialised;
  76
  77 static void handleMonitorEvent(struct HvLpEvent *event);
  78
  79 /*
  80  * We use this structure to handle asynchronous responses.  The caller
  81  * blocks on the semaphore and the handler posts the semaphore.  However,
  82  * if system_state is not SYSTEM_RUNNING, then wait_atomic is used ...
  83  */
  84 struct alloc_parms {
  85         struct semaphore sem;
  86         int number;
  87         atomic_t wait_atomic;
  88         int used_wait_atomic;
  89 };
  90
  91 /* Put a sequence number in each mon msg.  The value is not
  92  * important.  Start at something other than 0 just for
  93  * readability.  wrapping this is ok.
  94  */
  95 static u8 viomonseq = 22;
  96
  97 /* Our hosting logical partition.  We get this at startup
  98  * time, and different modules access this variable directly.
  99  */
 100 HvLpIndex viopath_hostLp = HvLpIndexInvalid;
 101 EXPORT_SYMBOL(viopath_hostLp);
 102 HvLpIndex viopath_ourLp = HvLpIndexInvalid;
 103 EXPORT_SYMBOL(viopath_ourLp);
 104
 105 /* For each kind of incoming event we set a pointer to a
 106  * routine to call.
 107  */
 108 static vio_event_handler_t *vio_handler[VIO_MAX_SUBTYPES];
 109
 110 #define VIOPATH_KERN_WARN       KERN_WARNING "viopath: "
 111 #define VIOPATH_KERN_INFO       KERN_INFO "viopath: "
 112
 113 static int proc_viopath_show(struct seq_file *m, void *v)
 114 {
 115         char *buf;
 116         u16 vlanMap;
 117         dma_addr_t handle;
 118         HvLpEvent_Rc hvrc;
 119         DECLARE_MUTEX_LOCKED(Semaphore);
 120         struct device_node *node;
 121         const char *sysid;
 122
 123         buf = kzalloc(HW_PAGE_SIZE, GFP_KERNEL);
 124         if (!buf)
 125                 return 0;
 126
 127         handle = dma_map_single(iSeries_vio_dev, buf, HW_PAGE_SIZE,
 128                                 DMA_FROM_DEVICE);
 129
 130         hvrc = HvCallEvent_signalLpEventFast(viopath_hostLp,
 131                         HvLpEvent_Type_VirtualIo,
 132                         viomajorsubtype_config | vioconfigget,
 133                         HvLpEvent_AckInd_DoAck, HvLpEvent_AckType_ImmediateAck,
 134                         viopath_sourceinst(viopath_hostLp),
 135                         viopath_targetinst(viopath_hostLp),
 136                         (u64)(unsigned long)&Semaphore, VIOVERSION << 16,
 137                         ((u64)handle) << 32, HW_PAGE_SIZE, 0, 0);
 138
 139         if (hvrc != HvLpEvent_Rc_Good)
 140                 printk(VIOPATH_KERN_WARN "hv error on op %d\n", (int)hvrc);
 141
 142         down(&Semaphore);
 143
 144         vlanMap = HvLpConfig_getVirtualLanIndexMap();
 145
 146         buf[HW_PAGE_SIZE-1] = '\0';
 147         seq_printf(m, "%s", buf);
 148
 149         dma_unmap_single(iSeries_vio_dev, handle, HW_PAGE_SIZE,
 150                          DMA_FROM_DEVICE);
 151         kfree(buf);
 152
 153         seq_printf(m, "AVAILABLE_VETH=%x\n", vlanMap);
 154
 155         node = of_find_node_by_path("/");
 156         sysid = NULL;
 157         if (node != NULL)
 158                 sysid = get_property(node, "system-id", NULL);
 159
 160         if (sysid == NULL)
 161                 seq_printf(m, "SRLNBR=<UNKNOWN>\n");
 162         else
 163                 /* Skip "IBM," on front of serial number, see dt.c */
 164                 seq_printf(m, "SRLNBR=%s\n", sysid + 4);
 165
 166         of_node_put(node);
 167
 168         return 0;
 169 }
 170
 171 static int proc_viopath_open(struct inode *inode, struct file *file)
 172 {
 173         return single_open(file, proc_viopath_show, NULL);
 174 }
 175
 176 static const struct file_operations proc_viopath_operations = {
 177         .open           = proc_viopath_open,
 178         .read           = seq_read,
 179         .llseek         = seq_lseek,
 180         .release        = single_release,
 181 };
 182
 183 static int __init vio_proc_init(void)
 184 {
 185         struct proc_dir_entry *e;
 186
 187         if (!firmware_has_feature(FW_FEATURE_ISERIES))
 188                 return 0;
 189
 190         e = create_proc_entry("iSeries/config", 0, NULL);
 191         if (e)
 192                 e->proc_fops = &proc_viopath_operations;
 193
 194         return 0;
 195 }
 196 __initcall(vio_proc_init);
 197
 198 /* See if a given LP is active.  Allow for invalid lps to be passed in
 199  * and just return invalid
 200  */
 201 int viopath_isactive(HvLpIndex lp)
 202 {
 203         if (lp == HvLpIndexInvalid)
 204                 return 0;
 205         if (lp < HVMAXARCHITECTEDLPS)
 206                 return viopathStatus[lp].isActive;
 207         else
 208                 return 0;
 209 }
 210 EXPORT_SYMBOL(viopath_isactive);
 211
 212 /*
 213  * We cache the source and target instance ids for each
 214  * partition.
 215  */
 216 HvLpInstanceId viopath_sourceinst(HvLpIndex lp)
 217 {
 218         return viopathStatus[lp].mSourceInst;
 219 }
 220 EXPORT_SYMBOL(viopath_sourceinst);
 221
 222 HvLpInstanceId viopath_targetinst(HvLpIndex lp)
 223 {
 224         return viopathStatus[lp].mTargetInst;
 225 }
 226 EXPORT_SYMBOL(viopath_targetinst);
 227
 228 /*
 229  * Send a monitor message.  This is a message with the acknowledge
 230  * bit on that the other side will NOT explicitly acknowledge.  When
 231  * the other side goes down, the hypervisor will acknowledge any
 232  * outstanding messages....so we will know when the other side dies.
 233  */
 234 static void sendMonMsg(HvLpIndex remoteLp)
 235 {
 236         HvLpEvent_Rc hvrc;
 237
 238         viopathStatus[remoteLp].mSourceInst =
 239                 HvCallEvent_getSourceLpInstanceId(remoteLp,
 240                                 HvLpEvent_Type_VirtualIo);
 241         viopathStatus[remoteLp].mTargetInst =
 242                 HvCallEvent_getTargetLpInstanceId(remoteLp,
 243                                 HvLpEvent_Type_VirtualIo);
 244
 245         /*
 246          * Deliberately ignore the return code here.  if we call this
 247          * more than once, we don't care.
 248          */
 249         vio_setHandler(viomajorsubtype_monitor, handleMonitorEvent);
 250
 251         hvrc = HvCallEvent_signalLpEventFast(remoteLp, HvLpEvent_Type_VirtualIo,
 252                         viomajorsubtype_monitor, HvLpEvent_AckInd_DoAck,
 253                         HvLpEvent_AckType_DeferredAck,
 254                         viopathStatus[remoteLp].mSourceInst,
 255                         viopathStatus[remoteLp].mTargetInst,
 256                         viomonseq++, 0, 0, 0, 0, 0);
 257
 258         if (hvrc == HvLpEvent_Rc_Good)
 259                 viopathStatus[remoteLp].isActive = 1;
 260         else {
 261                 printk(VIOPATH_KERN_WARN "could not connect to partition %d\n",
 262                                 remoteLp);
 263                 viopathStatus[remoteLp].isActive = 0;
 264         }
 265 }
 266
 267 static void handleMonitorEvent(struct HvLpEvent *event)
 268 {
 269         HvLpIndex remoteLp;
 270         int i;
 271
 272         /*
 273          * This handler is _also_ called as part of the loop
 274          * at the end of this routine, so it must be able to
 275          * ignore NULL events...
 276          */
 277         if (!event)
 278                 return;
 279
 280         /*
 281          * First see if this is just a normal monitor message from the
 282          * other partition
 283          */
 284         if (hvlpevent_is_int(event)) {
 285                 remoteLp = event->xSourceLp;
 286                 if (!viopathStatus[remoteLp].isActive)
 287                         sendMonMsg(remoteLp);
 288                 return;
 289         }
 290
 291         /*
 292          * This path is for an acknowledgement; the other partition
 293          * died
 294          */
 295         remoteLp = event->xTargetLp;
 296         if ((event->xSourceInstanceId != viopathStatus[remoteLp].mSourceInst) ||
 297             (event->xTargetInstanceId != viopathStatus[remoteLp].mTargetInst)) {
 298                 printk(VIOPATH_KERN_WARN "ignoring ack....mismatched instances\n");
 299                 return;
 300         }
 301
 302         printk(VIOPATH_KERN_WARN "partition %d ended\n", remoteLp);
 303
 304         viopathStatus[remoteLp].isActive = 0;
 305
 306         /*
 307          * For each active handler, pass them a NULL
 308          * message to indicate that the other partition
 309          * died
 310          */
 311         for (i = 0; i < VIO_MAX_SUBTYPES; i++) {
 312                 if (vio_handler[i] != NULL)
 313                         (*vio_handler[i])(NULL);
 314         }
 315 }
 316
 317 int vio_setHandler(int subtype, vio_event_handler_t *beh)
 318 {
 319         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 320         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 321                 return -EINVAL;
 322         if (vio_handler[subtype] != NULL)
 323                 return -EBUSY;
 324         vio_handler[subtype] = beh;
 325         return 0;
 326 }
 327 EXPORT_SYMBOL(vio_setHandler);
 328
 329 int vio_clearHandler(int subtype)
 330 {
 331         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 332         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 333                 return -EINVAL;
 334         if (vio_handler[subtype] == NULL)
 335                 return -EAGAIN;
 336         vio_handler[subtype] = NULL;
 337         return 0;
 338 }
 339 EXPORT_SYMBOL(vio_clearHandler);
 340
 341 static void handleConfig(struct HvLpEvent *event)
 342 {
 343         if (!event)
 344                 return;
 345         if (hvlpevent_is_int(event)) {
 346                 printk(VIOPATH_KERN_WARN
 347                        "unexpected config request from partition %d",
 348                        event->xSourceLp);
 349
 350                 if (hvlpevent_need_ack(event)) {
 351                         event->xRc = HvLpEvent_Rc_InvalidSubtype;
 352                         HvCallEvent_ackLpEvent(event);
 353                 }
 354                 return;
 355         }
 356
 357         up((struct semaphore *)event->xCorrelationToken);
 358 }
 359
 360 /*
 361  * Initialization of the hosting partition
 362  */
 363 void vio_set_hostlp(void)
 364 {
 365         /*
 366          * If this has already been set then we DON'T want to either change
 367          * it or re-register the proc file system
 368          */
 369         if (viopath_hostLp != HvLpIndexInvalid)
 370                 return;
 371
 372         /*
 373          * Figure out our hosting partition.  This isn't allowed to change
 374          * while we're active
 375          */
 376         viopath_ourLp = HvLpConfig_getLpIndex();
 377         viopath_hostLp = HvLpConfig_getHostingLpIndex(viopath_ourLp);
 378
 379         if (viopath_hostLp != HvLpIndexInvalid)
 380                 vio_setHandler(viomajorsubtype_config, handleConfig);
 381 }
 382 EXPORT_SYMBOL(vio_set_hostlp);
 383
 384 static void vio_handleEvent(struct HvLpEvent *event)
 385 {
 386         HvLpIndex remoteLp;
 387         int subtype = (event->xSubtype & VIOMAJOR_SUBTYPE_MASK)
 388                 >> VIOMAJOR_SUBTYPE_SHIFT;
 389
 390         if (hvlpevent_is_int(event)) {
 391                 remoteLp = event->xSourceLp;
 392                 /*
 393                  * The isActive is checked because if the hosting partition
 394                  * went down and came back up it would not be active but it
 395                  * would have different source and target instances, in which
 396                  * case we'd want to reset them.  This case really protects
 397                  * against an unauthorized active partition sending interrupts
 398                  * or acks to this linux partition.
 399                  */
 400                 if (viopathStatus[remoteLp].isActive
 401                     && (event->xSourceInstanceId !=
 402                         viopathStatus[remoteLp].mTargetInst)) {
 403                         printk(VIOPATH_KERN_WARN
 404                                "message from invalid partition. "
 405                                "int msg rcvd, source inst (%d) doesnt match (%d)\n",
 406                                viopathStatus[remoteLp].mTargetInst,
 407                                event->xSourceInstanceId);
 408                         return;
 409                 }
 410
 411                 if (viopathStatus[remoteLp].isActive
 412                     && (event->xTargetInstanceId !=
 413                         viopathStatus[remoteLp].mSourceInst)) {
 414                         printk(VIOPATH_KERN_WARN
 415                                "message from invalid partition. "
 416                                "int msg rcvd, target inst (%d) doesnt match (%d)\n",
 417                                viopathStatus[remoteLp].mSourceInst,
 418                                event->xTargetInstanceId);
 419                         return;
 420                 }
 421         } else {
 422                 remoteLp = event->xTargetLp;
 423                 if (event->xSourceInstanceId !=
 424                     viopathStatus[remoteLp].mSourceInst) {
 425                         printk(VIOPATH_KERN_WARN
 426                                "message from invalid partition. "
 427                                "ack msg rcvd, source inst (%d) doesnt match (%d)\n",
 428                                viopathStatus[remoteLp].mSourceInst,
 429                                event->xSourceInstanceId);
 430                         return;
 431                 }
 432
 433                 if (event->xTargetInstanceId !=
 434                     viopathStatus[remoteLp].mTargetInst) {
 435                         printk(VIOPATH_KERN_WARN
 436                                "message from invalid partition. "
 437                                "viopath: ack msg rcvd, target inst (%d) doesnt match (%d)\n",
 438                                viopathStatus[remoteLp].mTargetInst,
 439                                event->xTargetInstanceId);
 440                         return;
 441                 }
 442         }
 443
 444         if (vio_handler[subtype] == NULL) {
 445                 printk(VIOPATH_KERN_WARN
 446                        "unexpected virtual io event subtype %d from partition %d\n",
 447                        event->xSubtype, remoteLp);
 448                 /* No handler.  Ack if necessary */
 449                 if (hvlpevent_is_int(event) && hvlpevent_need_ack(event)) {
 450                         event->xRc = HvLpEvent_Rc_InvalidSubtype;
 451                         HvCallEvent_ackLpEvent(event);
 452                 }
 453                 return;
 454         }
 455
 456         /* This innocuous little line is where all the real work happens */
 457         (*vio_handler[subtype])(event);
 458 }
 459
 460 static void viopath_donealloc(void *parm, int number)
 461 {
 462         struct alloc_parms *parmsp = parm;
 463
 464         parmsp->number = number;
 465         if (parmsp->used_wait_atomic)
 466                 atomic_set(&parmsp->wait_atomic, 0);
 467         else
 468                 up(&parmsp->sem);
 469 }
 470
 471 static int allocateEvents(HvLpIndex remoteLp, int numEvents)
 472 {
 473         struct alloc_parms parms;
 474
 475         if (system_state != SYSTEM_RUNNING) {
 476                 parms.used_wait_atomic = 1;
 477                 atomic_set(&parms.wait_atomic, 1);
 478         } else {
 479                 parms.used_wait_atomic = 0;
 480                 init_MUTEX_LOCKED(&parms.sem);
 481         }
 482         mf_allocate_lp_events(remoteLp, HvLpEvent_Type_VirtualIo, 250,  /* It would be nice to put a real number here! */
 483                             numEvents, &viopath_donealloc, &parms);
 484         if (system_state != SYSTEM_RUNNING) {
 485                 while (atomic_read(&parms.wait_atomic))
 486                         mb();
 487         } else
 488                 down(&parms.sem);
 489         return parms.number;
 490 }
 491
 492 int viopath_open(HvLpIndex remoteLp, int subtype, int numReq)
 493 {
 494         int i;
 495         unsigned long flags;
 496         int tempNumAllocated;
 497
 498         if ((remoteLp >= HVMAXARCHITECTEDLPS) || (remoteLp == HvLpIndexInvalid))
 499                 return -EINVAL;
 500
 501         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 502         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 503                 return -EINVAL;
 504
 505         spin_lock_irqsave(&statuslock, flags);
 506
 507         if (!event_buffer_initialised) {
 508                 for (i = 0; i < VIO_MAX_SUBTYPES; i++)
 509                         atomic_set(&event_buffer_available[i], 1);
 510                 event_buffer_initialised = 1;
 511         }
 512
 513         viopathStatus[remoteLp].users[subtype]++;
 514
 515         if (!viopathStatus[remoteLp].isOpen) {
 516                 viopathStatus[remoteLp].isOpen = 1;
 517                 HvCallEvent_openLpEventPath(remoteLp, HvLpEvent_Type_VirtualIo);
 518
 519                 /*
 520                  * Don't hold the spinlock during an operation that
 521                  * can sleep.
 522                  */
 523                 spin_unlock_irqrestore(&statuslock, flags);
 524                 tempNumAllocated = allocateEvents(remoteLp, 1);
 525                 spin_lock_irqsave(&statuslock, flags);
 526
 527                 viopathStatus[remoteLp].numberAllocated += tempNumAllocated;
 528
 529                 if (viopathStatus[remoteLp].numberAllocated == 0) {
 530                         HvCallEvent_closeLpEventPath(remoteLp,
 531                                         HvLpEvent_Type_VirtualIo);
 532
 533                         spin_unlock_irqrestore(&statuslock, flags);
 534                         return -ENOMEM;
 535                 }
 536
 537                 viopathStatus[remoteLp].mSourceInst =
 538                         HvCallEvent_getSourceLpInstanceId(remoteLp,
 539                                         HvLpEvent_Type_VirtualIo);
 540                 viopathStatus[remoteLp].mTargetInst =
 541                         HvCallEvent_getTargetLpInstanceId(remoteLp,
 542                                         HvLpEvent_Type_VirtualIo);
 543                 HvLpEvent_registerHandler(HvLpEvent_Type_VirtualIo,
 544                                           &vio_handleEvent);
 545                 sendMonMsg(remoteLp);
 546                 printk(VIOPATH_KERN_INFO "opening connection to partition %d, "
 547                                 "setting sinst %d, tinst %d\n",
 548                                 remoteLp, viopathStatus[remoteLp].mSourceInst,
 549                                 viopathStatus[remoteLp].mTargetInst);
 550         }
 551
 552         spin_unlock_irqrestore(&statuslock, flags);
 553         tempNumAllocated = allocateEvents(remoteLp, numReq);
 554         spin_lock_irqsave(&statuslock, flags);
 555         viopathStatus[remoteLp].numberAllocated += tempNumAllocated;
 556         spin_unlock_irqrestore(&statuslock, flags);
 557
 558         return 0;
 559 }
 560 EXPORT_SYMBOL(viopath_open);
 561
 562 int viopath_close(HvLpIndex remoteLp, int subtype, int numReq)
 563 {
 564         unsigned long flags;
 565         int i;
 566         int numOpen;
 567         struct alloc_parms parms;
 568
 569         if ((remoteLp >= HVMAXARCHITECTEDLPS) || (remoteLp == HvLpIndexInvalid))
 570                 return -EINVAL;
 571
 572         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 573         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 574                 return -EINVAL;
 575
 576         spin_lock_irqsave(&statuslock, flags);
 577         /*
 578          * If the viopath_close somehow gets called before a
 579          * viopath_open it could decrement to -1 which is a non
 580          * recoverable state so we'll prevent this from
 581          * happening.
 582          */
 583         if (viopathStatus[remoteLp].users[subtype] > 0)
 584                 viopathStatus[remoteLp].users[subtype]--;
 585
 586         spin_unlock_irqrestore(&statuslock, flags);
 587
 588         parms.used_wait_atomic = 0;
 589         init_MUTEX_LOCKED(&parms.sem);
 590         mf_deallocate_lp_events(remoteLp, HvLpEvent_Type_VirtualIo,
 591                               numReq, &viopath_donealloc, &parms);
 592         down(&parms.sem);
 593
 594         spin_lock_irqsave(&statuslock, flags);
 595         for (i = 0, numOpen = 0; i < VIO_MAX_SUBTYPES; i++)
 596                 numOpen += viopathStatus[remoteLp].users[i];
 597
 598         if ((viopathStatus[remoteLp].isOpen) && (numOpen == 0)) {
 599                 printk(VIOPATH_KERN_INFO "closing connection to partition %d",
 600                                 remoteLp);
 601
 602                 HvCallEvent_closeLpEventPath(remoteLp,
 603                                              HvLpEvent_Type_VirtualIo);
 604                 viopathStatus[remoteLp].isOpen = 0;
 605                 viopathStatus[remoteLp].isActive = 0;
 606
 607                 for (i = 0; i < VIO_MAX_SUBTYPES; i++)
 608                         atomic_set(&event_buffer_available[i], 0);
 609                 event_buffer_initialised = 0;
 610         }
 611         spin_unlock_irqrestore(&statuslock, flags);
 612         return 0;
 613 }
 614 EXPORT_SYMBOL(viopath_close);
 615
 616 void *vio_get_event_buffer(int subtype)
 617 {
 618         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 619         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 620                 return NULL;
 621
 622         if (atomic_dec_if_positive(&event_buffer_available[subtype]) == 0)
 623                 return &event_buffer[subtype * 256];
 624         else
 625                 return NULL;
 626 }
 627 EXPORT_SYMBOL(vio_get_event_buffer);
 628
 629 void vio_free_event_buffer(int subtype, void *buffer)
 630 {
 631         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 632         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES)) {
 633                 printk(VIOPATH_KERN_WARN
 634                        "unexpected subtype %d freeing event buffer\n", subtype);
 635                 return;
 636         }
 637
 638         if (atomic_read(&event_buffer_available[subtype]) != 0) {
 639                 printk(VIOPATH_KERN_WARN
 640                        "freeing unallocated event buffer, subtype %d\n",
 641                        subtype);
 642                 return;
 643         }
 644
 645         if (buffer != &event_buffer[subtype * 256]) {
 646                 printk(VIOPATH_KERN_WARN
 647                        "freeing invalid event buffer, subtype %d\n", subtype);
 648         }
 649
 650         atomic_set(&event_buffer_available[subtype], 1);
 651 }
 652 EXPORT_SYMBOL(vio_free_event_buffer);
 653
 654 static const struct vio_error_entry vio_no_error =
 655     { 0, 0, "Non-VIO Error" };
 656 static const struct vio_error_entry vio_unknown_error =
 657     { 0, EIO, "Unknown Error" };
 658
 659 static const struct vio_error_entry vio_default_errors[] = {
 660         {0x0001, EIO, "No Connection"},
 661         {0x0002, EIO, "No Receiver"},
 662         {0x0003, EIO, "No Buffer Available"},
 663         {0x0004, EBADRQC, "Invalid Message Type"},
 664         {0x0000, 0, NULL},
 665 };
 666
 667 const struct vio_error_entry *vio_lookup_rc(
 668                 const struct vio_error_entry *local_table, u16 rc)
 669 {
 670         const struct vio_error_entry *cur;
 671
 672         if (!rc)
 673                 return &vio_no_error;
 674         if (local_table)
 675                 for (cur = local_table; cur->rc; ++cur)
 676                         if (cur->rc == rc)
 677                                 return cur;
 678         for (cur = vio_default_errors; cur->rc; ++cur)
 679                 if (cur->rc == rc)
 680                         return cur;
 681         return &vio_unknown_error;
 682 }
 683 EXPORT_SYMBOL(vio_lookup_rc);