err.no Git - linux-2.6/blob - 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/interrupt.h>
  40
  41 #include <asm/system.h>
  42 #include <asm/uaccess.h>
  43 #include <asm/prom.h>
  44 #include <asm/firmware.h>
  45 #include <asm/iseries/hv_types.h>
  46 #include <asm/iseries/hv_lp_event.h>
  47 #include <asm/iseries/hv_lp_config.h>
  48 #include <asm/iseries/mf.h>
  49 #include <asm/iseries/vio.h>
  50
  51 /* Status of the path to each other partition in the system.
  52  * This is overkill, since we will only ever establish connections
  53  * to our hosting partition and the primary partition on the system.
  54  * But this allows for other support in the future.
  55  */
  56 static struct viopathStatus {
  57         int isOpen;             /* Did we open the path?            */
  58         int isActive;           /* Do we have a mon msg outstanding */
  59         int users[VIO_MAX_SUBTYPES];
  60         HvLpInstanceId mSourceInst;
  61         HvLpInstanceId mTargetInst;
  62         int numberAllocated;
  63 } viopathStatus[HVMAXARCHITECTEDLPS];
  64
  65 static DEFINE_SPINLOCK(statuslock);
  66
  67 /*
  68  * For each kind of event we allocate a buffer that is
  69  * guaranteed not to cross a page boundary
  70  */
  71 static unsigned char event_buffer[VIO_MAX_SUBTYPES * 256]
  72         __attribute__((__aligned__(4096)));
  73 static atomic_t event_buffer_available[VIO_MAX_SUBTYPES];
  74 static int event_buffer_initialised;
  75
  76 static void handleMonitorEvent(struct HvLpEvent *event);
  77
  78 /*
  79  * We use this structure to handle asynchronous responses.  The caller
  80  * blocks on the semaphore and the handler posts the semaphore.  However,
  81  * if system_state is not SYSTEM_RUNNING, then wait_atomic is used ...
  82  */
  83 struct alloc_parms {
  84         struct semaphore sem;
  85         int number;
  86         atomic_t wait_atomic;
  87         int used_wait_atomic;
  88 };
  89
  90 /* Put a sequence number in each mon msg.  The value is not
  91  * important.  Start at something other than 0 just for
  92  * readability.  wrapping this is ok.
  93  */
  94 static u8 viomonseq = 22;
  95
  96 /* Our hosting logical partition.  We get this at startup
  97  * time, and different modules access this variable directly.
  98  */
  99 HvLpIndex viopath_hostLp = HvLpIndexInvalid;
 100 EXPORT_SYMBOL(viopath_hostLp);
 101 HvLpIndex viopath_ourLp = HvLpIndexInvalid;
 102 EXPORT_SYMBOL(viopath_ourLp);
 103
 104 /* For each kind of incoming event we set a pointer to a
 105  * routine to call.
 106  */
 107 static vio_event_handler_t *vio_handler[VIO_MAX_SUBTYPES];
 108
 109 #define VIOPATH_KERN_WARN       KERN_WARNING "viopath: "
 110 #define VIOPATH_KERN_INFO       KERN_INFO "viopath: "
 111
 112 static int proc_viopath_show(struct seq_file *m, void *v)
 113 {
 114         char *buf;
 115         u16 vlanMap;
 116         dma_addr_t handle;
 117         HvLpEvent_Rc hvrc;
 118         DECLARE_MUTEX_LOCKED(Semaphore);
 119         struct device_node *node;
 120         const char *sysid;
 121
 122         buf = kzalloc(HW_PAGE_SIZE, GFP_KERNEL);
 123         if (!buf)
 124                 return 0;
 125
 126         handle = dma_map_single(iSeries_vio_dev, buf, HW_PAGE_SIZE,
 127                                 DMA_FROM_DEVICE);
 128
 129         hvrc = HvCallEvent_signalLpEventFast(viopath_hostLp,
 130                         HvLpEvent_Type_VirtualIo,
 131                         viomajorsubtype_config | vioconfigget,
 132                         HvLpEvent_AckInd_DoAck, HvLpEvent_AckType_ImmediateAck,
 133                         viopath_sourceinst(viopath_hostLp),
 134                         viopath_targetinst(viopath_hostLp),
 135                         (u64)(unsigned long)&Semaphore, VIOVERSION << 16,
 136                         ((u64)handle) << 32, HW_PAGE_SIZE, 0, 0);
 137
 138         if (hvrc != HvLpEvent_Rc_Good)
 139                 printk(VIOPATH_KERN_WARN "hv error on op %d\n", (int)hvrc);
 140
 141         down(&Semaphore);
 142
 143         vlanMap = HvLpConfig_getVirtualLanIndexMap();
 144
 145         buf[HW_PAGE_SIZE-1] = '\0';
 146         seq_printf(m, "%s", buf);
 147
 148         dma_unmap_single(iSeries_vio_dev, handle, HW_PAGE_SIZE,
 149                          DMA_FROM_DEVICE);
 150         kfree(buf);
 151
 152         seq_printf(m, "AVAILABLE_VETH=%x\n", vlanMap);
 153
 154         node = of_find_node_by_path("/");
 155         sysid = NULL;
 156         if (node != NULL)
 157                 sysid = of_get_property(node, "system-id", NULL);
 158
 159         if (sysid == NULL)
 160                 seq_printf(m, "SRLNBR=<UNKNOWN>\n");
 161         else
 162                 /* Skip "IBM," on front of serial number, see dt.c */
 163                 seq_printf(m, "SRLNBR=%s\n", sysid + 4);
 164
 165         of_node_put(node);
 166
 167         return 0;
 168 }
 169
 170 static int proc_viopath_open(struct inode *inode, struct file *file)
 171 {
 172         return single_open(file, proc_viopath_show, NULL);
 173 }
 174
 175 static const struct file_operations proc_viopath_operations = {
 176         .open           = proc_viopath_open,
 177         .read           = seq_read,
 178         .llseek         = seq_lseek,
 179         .release        = single_release,
 180 };
 181
 182 static int __init vio_proc_init(void)
 183 {
 184         struct proc_dir_entry *e;
 185
 186         if (!firmware_has_feature(FW_FEATURE_ISERIES))
 187                 return 0;
 188
 189         e = create_proc_entry("iSeries/config", 0, NULL);
 190         if (e)
 191                 e->proc_fops = &proc_viopath_operations;
 192
 193         return 0;
 194 }
 195 __initcall(vio_proc_init);
 196
 197 /* See if a given LP is active.  Allow for invalid lps to be passed in
 198  * and just return invalid
 199  */
 200 int viopath_isactive(HvLpIndex lp)
 201 {
 202         if (lp == HvLpIndexInvalid)
 203                 return 0;
 204         if (lp < HVMAXARCHITECTEDLPS)
 205                 return viopathStatus[lp].isActive;
 206         else
 207                 return 0;
 208 }
 209 EXPORT_SYMBOL(viopath_isactive);
 210
 211 /*
 212  * We cache the source and target instance ids for each
 213  * partition.
 214  */
 215 HvLpInstanceId viopath_sourceinst(HvLpIndex lp)
 216 {
 217         return viopathStatus[lp].mSourceInst;
 218 }
 219 EXPORT_SYMBOL(viopath_sourceinst);
 220
 221 HvLpInstanceId viopath_targetinst(HvLpIndex lp)
 222 {
 223         return viopathStatus[lp].mTargetInst;
 224 }
 225 EXPORT_SYMBOL(viopath_targetinst);
 226
 227 /*
 228  * Send a monitor message.  This is a message with the acknowledge
 229  * bit on that the other side will NOT explicitly acknowledge.  When
 230  * the other side goes down, the hypervisor will acknowledge any
 231  * outstanding messages....so we will know when the other side dies.
 232  */
 233 static void sendMonMsg(HvLpIndex remoteLp)
 234 {
 235         HvLpEvent_Rc hvrc;
 236
 237         viopathStatus[remoteLp].mSourceInst =
 238                 HvCallEvent_getSourceLpInstanceId(remoteLp,
 239                                 HvLpEvent_Type_VirtualIo);
 240         viopathStatus[remoteLp].mTargetInst =
 241                 HvCallEvent_getTargetLpInstanceId(remoteLp,
 242                                 HvLpEvent_Type_VirtualIo);
 243
 244         /*
 245          * Deliberately ignore the return code here.  if we call this
 246          * more than once, we don't care.
 247          */
 248         vio_setHandler(viomajorsubtype_monitor, handleMonitorEvent);
 249
 250         hvrc = HvCallEvent_signalLpEventFast(remoteLp, HvLpEvent_Type_VirtualIo,
 251                         viomajorsubtype_monitor, HvLpEvent_AckInd_DoAck,
 252                         HvLpEvent_AckType_DeferredAck,
 253                         viopathStatus[remoteLp].mSourceInst,
 254                         viopathStatus[remoteLp].mTargetInst,
 255                         viomonseq++, 0, 0, 0, 0, 0);
 256
 257         if (hvrc == HvLpEvent_Rc_Good)
 258                 viopathStatus[remoteLp].isActive = 1;
 259         else {
 260                 printk(VIOPATH_KERN_WARN "could not connect to partition %d\n",
 261                                 remoteLp);
 262                 viopathStatus[remoteLp].isActive = 0;
 263         }
 264 }
 265
 266 static void handleMonitorEvent(struct HvLpEvent *event)
 267 {
 268         HvLpIndex remoteLp;
 269         int i;
 270
 271         /*
 272          * This handler is _also_ called as part of the loop
 273          * at the end of this routine, so it must be able to
 274          * ignore NULL events...
 275          */
 276         if (!event)
 277                 return;
 278
 279         /*
 280          * First see if this is just a normal monitor message from the
 281          * other partition
 282          */
 283         if (hvlpevent_is_int(event)) {
 284                 remoteLp = event->xSourceLp;
 285                 if (!viopathStatus[remoteLp].isActive)
 286                         sendMonMsg(remoteLp);
 287                 return;
 288         }
 289
 290         /*
 291          * This path is for an acknowledgement; the other partition
 292          * died
 293          */
 294         remoteLp = event->xTargetLp;
 295         if ((event->xSourceInstanceId != viopathStatus[remoteLp].mSourceInst) ||
 296             (event->xTargetInstanceId != viopathStatus[remoteLp].mTargetInst)) {
 297                 printk(VIOPATH_KERN_WARN "ignoring ack....mismatched instances\n");
 298                 return;
 299         }
 300
 301         printk(VIOPATH_KERN_WARN "partition %d ended\n", remoteLp);
 302
 303         viopathStatus[remoteLp].isActive = 0;
 304
 305         /*
 306          * For each active handler, pass them a NULL
 307          * message to indicate that the other partition
 308          * died
 309          */
 310         for (i = 0; i < VIO_MAX_SUBTYPES; i++) {
 311                 if (vio_handler[i] != NULL)
 312                         (*vio_handler[i])(NULL);
 313         }
 314 }
 315
 316 int vio_setHandler(int subtype, vio_event_handler_t *beh)
 317 {
 318         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 319         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 320                 return -EINVAL;
 321         if (vio_handler[subtype] != NULL)
 322                 return -EBUSY;
 323         vio_handler[subtype] = beh;
 324         return 0;
 325 }
 326 EXPORT_SYMBOL(vio_setHandler);
 327
 328 int vio_clearHandler(int subtype)
 329 {
 330         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 331         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 332                 return -EINVAL;
 333         if (vio_handler[subtype] == NULL)
 334                 return -EAGAIN;
 335         vio_handler[subtype] = NULL;
 336         return 0;
 337 }
 338 EXPORT_SYMBOL(vio_clearHandler);
 339
 340 static void handleConfig(struct HvLpEvent *event)
 341 {
 342         if (!event)
 343                 return;
 344         if (hvlpevent_is_int(event)) {
 345                 printk(VIOPATH_KERN_WARN
 346                        "unexpected config request from partition %d",
 347                        event->xSourceLp);
 348
 349                 if (hvlpevent_need_ack(event)) {
 350                         event->xRc = HvLpEvent_Rc_InvalidSubtype;
 351                         HvCallEvent_ackLpEvent(event);
 352                 }
 353                 return;
 354         }
 355
 356         up((struct semaphore *)event->xCorrelationToken);
 357 }
 358
 359 /*
 360  * Initialization of the hosting partition
 361  */
 362 void vio_set_hostlp(void)
 363 {
 364         /*
 365          * If this has already been set then we DON'T want to either change
 366          * it or re-register the proc file system
 367          */
 368         if (viopath_hostLp != HvLpIndexInvalid)
 369                 return;
 370
 371         /*
 372          * Figure out our hosting partition.  This isn't allowed to change
 373          * while we're active
 374          */
 375         viopath_ourLp = HvLpConfig_getLpIndex();
 376         viopath_hostLp = HvLpConfig_getHostingLpIndex(viopath_ourLp);
 377
 378         if (viopath_hostLp != HvLpIndexInvalid)
 379                 vio_setHandler(viomajorsubtype_config, handleConfig);
 380 }
 381 EXPORT_SYMBOL(vio_set_hostlp);
 382
 383 static void vio_handleEvent(struct HvLpEvent *event)
 384 {
 385         HvLpIndex remoteLp;
 386         int subtype = (event->xSubtype & VIOMAJOR_SUBTYPE_MASK)
 387                 >> VIOMAJOR_SUBTYPE_SHIFT;
 388
 389         if (hvlpevent_is_int(event)) {
 390                 remoteLp = event->xSourceLp;
 391                 /*
 392                  * The isActive is checked because if the hosting partition
 393                  * went down and came back up it would not be active but it
 394                  * would have different source and target instances, in which
 395                  * case we'd want to reset them.  This case really protects
 396                  * against an unauthorized active partition sending interrupts
 397                  * or acks to this linux partition.
 398                  */
 399                 if (viopathStatus[remoteLp].isActive
 400                     && (event->xSourceInstanceId !=
 401                         viopathStatus[remoteLp].mTargetInst)) {
 402                         printk(VIOPATH_KERN_WARN
 403                                "message from invalid partition. "
 404                                "int msg rcvd, source inst (%d) doesnt match (%d)\n",
 405                                viopathStatus[remoteLp].mTargetInst,
 406                                event->xSourceInstanceId);
 407                         return;
 408                 }
 409
 410                 if (viopathStatus[remoteLp].isActive
 411                     && (event->xTargetInstanceId !=
 412                         viopathStatus[remoteLp].mSourceInst)) {
 413                         printk(VIOPATH_KERN_WARN
 414                                "message from invalid partition. "
 415                                "int msg rcvd, target inst (%d) doesnt match (%d)\n",
 416                                viopathStatus[remoteLp].mSourceInst,
 417                                event->xTargetInstanceId);
 418                         return;
 419                 }
 420         } else {
 421                 remoteLp = event->xTargetLp;
 422                 if (event->xSourceInstanceId !=
 423                     viopathStatus[remoteLp].mSourceInst) {
 424                         printk(VIOPATH_KERN_WARN
 425                                "message from invalid partition. "
 426                                "ack msg rcvd, source inst (%d) doesnt match (%d)\n",
 427                                viopathStatus[remoteLp].mSourceInst,
 428                                event->xSourceInstanceId);
 429                         return;
 430                 }
 431
 432                 if (event->xTargetInstanceId !=
 433                     viopathStatus[remoteLp].mTargetInst) {
 434                         printk(VIOPATH_KERN_WARN
 435                                "message from invalid partition. "
 436                                "viopath: ack msg rcvd, target inst (%d) doesnt match (%d)\n",
 437                                viopathStatus[remoteLp].mTargetInst,
 438                                event->xTargetInstanceId);
 439                         return;
 440                 }
 441         }
 442
 443         if (vio_handler[subtype] == NULL) {
 444                 printk(VIOPATH_KERN_WARN
 445                        "unexpected virtual io event subtype %d from partition %d\n",
 446                        event->xSubtype, remoteLp);
 447                 /* No handler.  Ack if necessary */
 448                 if (hvlpevent_is_int(event) && hvlpevent_need_ack(event)) {
 449                         event->xRc = HvLpEvent_Rc_InvalidSubtype;
 450                         HvCallEvent_ackLpEvent(event);
 451                 }
 452                 return;
 453         }
 454
 455         /* This innocuous little line is where all the real work happens */
 456         (*vio_handler[subtype])(event);
 457 }
 458
 459 static void viopath_donealloc(void *parm, int number)
 460 {
 461         struct alloc_parms *parmsp = parm;
 462
 463         parmsp->number = number;
 464         if (parmsp->used_wait_atomic)
 465                 atomic_set(&parmsp->wait_atomic, 0);
 466         else
 467                 up(&parmsp->sem);
 468 }
 469
 470 static int allocateEvents(HvLpIndex remoteLp, int numEvents)
 471 {
 472         struct alloc_parms parms;
 473
 474         if (system_state != SYSTEM_RUNNING) {
 475                 parms.used_wait_atomic = 1;
 476                 atomic_set(&parms.wait_atomic, 1);
 477         } else {
 478                 parms.used_wait_atomic = 0;
 479                 init_MUTEX_LOCKED(&parms.sem);
 480         }
 481         mf_allocate_lp_events(remoteLp, HvLpEvent_Type_VirtualIo, 250,  /* It would be nice to put a real number here! */
 482                             numEvents, &viopath_donealloc, &parms);
 483         if (system_state != SYSTEM_RUNNING) {
 484                 while (atomic_read(&parms.wait_atomic))
 485                         mb();
 486         } else
 487                 down(&parms.sem);
 488         return parms.number;
 489 }
 490
 491 int viopath_open(HvLpIndex remoteLp, int subtype, int numReq)
 492 {
 493         int i;
 494         unsigned long flags;
 495         int tempNumAllocated;
 496
 497         if ((remoteLp >= HVMAXARCHITECTEDLPS) || (remoteLp == HvLpIndexInvalid))
 498                 return -EINVAL;
 499
 500         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 501         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 502                 return -EINVAL;
 503
 504         spin_lock_irqsave(&statuslock, flags);
 505
 506         if (!event_buffer_initialised) {
 507                 for (i = 0; i < VIO_MAX_SUBTYPES; i++)
 508                         atomic_set(&event_buffer_available[i], 1);
 509                 event_buffer_initialised = 1;
 510         }
 511
 512         viopathStatus[remoteLp].users[subtype]++;
 513
 514         if (!viopathStatus[remoteLp].isOpen) {
 515                 viopathStatus[remoteLp].isOpen = 1;
 516                 HvCallEvent_openLpEventPath(remoteLp, HvLpEvent_Type_VirtualIo);
 517
 518                 /*
 519                  * Don't hold the spinlock during an operation that
 520                  * can sleep.
 521                  */
 522                 spin_unlock_irqrestore(&statuslock, flags);
 523                 tempNumAllocated = allocateEvents(remoteLp, 1);
 524                 spin_lock_irqsave(&statuslock, flags);
 525
 526                 viopathStatus[remoteLp].numberAllocated += tempNumAllocated;
 527
 528                 if (viopathStatus[remoteLp].numberAllocated == 0) {
 529                         HvCallEvent_closeLpEventPath(remoteLp,
 530                                         HvLpEvent_Type_VirtualIo);
 531
 532                         spin_unlock_irqrestore(&statuslock, flags);
 533                         return -ENOMEM;
 534                 }
 535
 536                 viopathStatus[remoteLp].mSourceInst =
 537                         HvCallEvent_getSourceLpInstanceId(remoteLp,
 538                                         HvLpEvent_Type_VirtualIo);
 539                 viopathStatus[remoteLp].mTargetInst =
 540                         HvCallEvent_getTargetLpInstanceId(remoteLp,
 541                                         HvLpEvent_Type_VirtualIo);
 542                 HvLpEvent_registerHandler(HvLpEvent_Type_VirtualIo,
 543                                           &vio_handleEvent);
 544                 sendMonMsg(remoteLp);
 545                 printk(VIOPATH_KERN_INFO "opening connection to partition %d, "
 546                                 "setting sinst %d, tinst %d\n",
 547                                 remoteLp, viopathStatus[remoteLp].mSourceInst,
 548                                 viopathStatus[remoteLp].mTargetInst);
 549         }
 550
 551         spin_unlock_irqrestore(&statuslock, flags);
 552         tempNumAllocated = allocateEvents(remoteLp, numReq);
 553         spin_lock_irqsave(&statuslock, flags);
 554         viopathStatus[remoteLp].numberAllocated += tempNumAllocated;
 555         spin_unlock_irqrestore(&statuslock, flags);
 556
 557         return 0;
 558 }
 559 EXPORT_SYMBOL(viopath_open);
 560
 561 int viopath_close(HvLpIndex remoteLp, int subtype, int numReq)
 562 {
 563         unsigned long flags;
 564         int i;
 565         int numOpen;
 566         struct alloc_parms parms;
 567
 568         if ((remoteLp >= HVMAXARCHITECTEDLPS) || (remoteLp == HvLpIndexInvalid))
 569                 return -EINVAL;
 570
 571         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 572         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 573                 return -EINVAL;
 574
 575         spin_lock_irqsave(&statuslock, flags);
 576         /*
 577          * If the viopath_close somehow gets called before a
 578          * viopath_open it could decrement to -1 which is a non
 579          * recoverable state so we'll prevent this from
 580          * happening.
 581          */
 582         if (viopathStatus[remoteLp].users[subtype] > 0)
 583                 viopathStatus[remoteLp].users[subtype]--;
 584
 585         spin_unlock_irqrestore(&statuslock, flags);
 586
 587         parms.used_wait_atomic = 0;
 588         init_MUTEX_LOCKED(&parms.sem);
 589         mf_deallocate_lp_events(remoteLp, HvLpEvent_Type_VirtualIo,
 590                               numReq, &viopath_donealloc, &parms);
 591         down(&parms.sem);
 592
 593         spin_lock_irqsave(&statuslock, flags);
 594         for (i = 0, numOpen = 0; i < VIO_MAX_SUBTYPES; i++)
 595                 numOpen += viopathStatus[remoteLp].users[i];
 596
 597         if ((viopathStatus[remoteLp].isOpen) && (numOpen == 0)) {
 598                 printk(VIOPATH_KERN_INFO "closing connection to partition %d",
 599                                 remoteLp);
 600
 601                 HvCallEvent_closeLpEventPath(remoteLp,
 602                                              HvLpEvent_Type_VirtualIo);
 603                 viopathStatus[remoteLp].isOpen = 0;
 604                 viopathStatus[remoteLp].isActive = 0;
 605
 606                 for (i = 0; i < VIO_MAX_SUBTYPES; i++)
 607                         atomic_set(&event_buffer_available[i], 0);
 608                 event_buffer_initialised = 0;
 609         }
 610         spin_unlock_irqrestore(&statuslock, flags);
 611         return 0;
 612 }
 613 EXPORT_SYMBOL(viopath_close);
 614
 615 void *vio_get_event_buffer(int subtype)
 616 {
 617         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 618         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 619                 return NULL;
 620
 621         if (atomic_dec_if_positive(&event_buffer_available[subtype]) == 0)
 622                 return &event_buffer[subtype * 256];
 623         else
 624                 return NULL;
 625 }
 626 EXPORT_SYMBOL(vio_get_event_buffer);
 627
 628 void vio_free_event_buffer(int subtype, void *buffer)
 629 {
 630         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 631         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES)) {
 632                 printk(VIOPATH_KERN_WARN
 633                        "unexpected subtype %d freeing event buffer\n", subtype);
 634                 return;
 635         }
 636
 637         if (atomic_read(&event_buffer_available[subtype]) != 0) {
 638                 printk(VIOPATH_KERN_WARN
 639                        "freeing unallocated event buffer, subtype %d\n",
 640                        subtype);
 641                 return;
 642         }
 643
 644         if (buffer != &event_buffer[subtype * 256]) {
 645                 printk(VIOPATH_KERN_WARN
 646                        "freeing invalid event buffer, subtype %d\n", subtype);
 647         }
 648
 649         atomic_set(&event_buffer_available[subtype], 1);
 650 }
 651 EXPORT_SYMBOL(vio_free_event_buffer);
 652
 653 static const struct vio_error_entry vio_no_error =
 654     { 0, 0, "Non-VIO Error" };
 655 static const struct vio_error_entry vio_unknown_error =
 656     { 0, EIO, "Unknown Error" };
 657
 658 static const struct vio_error_entry vio_default_errors[] = {
 659         {0x0001, EIO, "No Connection"},
 660         {0x0002, EIO, "No Receiver"},
 661         {0x0003, EIO, "No Buffer Available"},
 662         {0x0004, EBADRQC, "Invalid Message Type"},
 663         {0x0000, 0, NULL},
 664 };
 665
 666 const struct vio_error_entry *vio_lookup_rc(
 667                 const struct vio_error_entry *local_table, u16 rc)
 668 {
 669         const struct vio_error_entry *cur;
 670
 671         if (!rc)
 672                 return &vio_no_error;
 673         if (local_table)
 674                 for (cur = local_table; cur->rc; ++cur)
 675                         if (cur->rc == rc)
 676                                 return cur;
 677         for (cur = vio_default_errors; cur->rc; ++cur)
 678                 if (cur->rc == rc)
 679                         return cur;
 680         return &vio_unknown_error;
 681 }
 682 EXPORT_SYMBOL(vio_lookup_rc);