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/iseries/hv_types.h>
  45 #include <asm/iseries/it_exp_vpd_panel.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
 120         buf = kmalloc(HW_PAGE_SIZE, GFP_KERNEL);
 121         if (!buf)
 122                 return 0;
 123         memset(buf, 0, HW_PAGE_SIZE);
 124
 125         handle = dma_map_single(iSeries_vio_dev, buf, HW_PAGE_SIZE,
 126                                 DMA_FROM_DEVICE);
 127
 128         hvrc = HvCallEvent_signalLpEventFast(viopath_hostLp,
 129                         HvLpEvent_Type_VirtualIo,
 130                         viomajorsubtype_config | vioconfigget,
 131                         HvLpEvent_AckInd_DoAck, HvLpEvent_AckType_ImmediateAck,
 132                         viopath_sourceinst(viopath_hostLp),
 133                         viopath_targetinst(viopath_hostLp),
 134                         (u64)(unsigned long)&Semaphore, VIOVERSION << 16,
 135                         ((u64)handle) << 32, HW_PAGE_SIZE, 0, 0);
 136
 137         if (hvrc != HvLpEvent_Rc_Good)
 138                 printk(VIOPATH_KERN_WARN "hv error on op %d\n", (int)hvrc);
 139
 140         down(&Semaphore);
 141
 142         vlanMap = HvLpConfig_getVirtualLanIndexMap();
 143
 144         buf[HW_PAGE_SIZE-1] = '\0';
 145         seq_printf(m, "%s", buf);
 146         seq_printf(m, "AVAILABLE_VETH=%x\n", vlanMap);
 147         seq_printf(m, "SRLNBR=%c%c%c%c%c%c%c\n",
 148                    e2a(xItExtVpdPanel.mfgID[2]),
 149                    e2a(xItExtVpdPanel.mfgID[3]),
 150                    e2a(xItExtVpdPanel.systemSerial[1]),
 151                    e2a(xItExtVpdPanel.systemSerial[2]),
 152                    e2a(xItExtVpdPanel.systemSerial[3]),
 153                    e2a(xItExtVpdPanel.systemSerial[4]),
 154                    e2a(xItExtVpdPanel.systemSerial[5]));
 155
 156         dma_unmap_single(iSeries_vio_dev, handle, HW_PAGE_SIZE,
 157                          DMA_FROM_DEVICE);
 158         kfree(buf);
 159
 160         return 0;
 161 }
 162
 163 static int proc_viopath_open(struct inode *inode, struct file *file)
 164 {
 165         return single_open(file, proc_viopath_show, NULL);
 166 }
 167
 168 static struct file_operations proc_viopath_operations = {
 169         .open           = proc_viopath_open,
 170         .read           = seq_read,
 171         .llseek         = seq_lseek,
 172         .release        = single_release,
 173 };
 174
 175 static int __init vio_proc_init(void)
 176 {
 177         struct proc_dir_entry *e;
 178
 179         e = create_proc_entry("iSeries/config", 0, NULL);
 180         if (e)
 181                 e->proc_fops = &proc_viopath_operations;
 182
 183         return 0;
 184 }
 185 __initcall(vio_proc_init);
 186
 187 /* See if a given LP is active.  Allow for invalid lps to be passed in
 188  * and just return invalid
 189  */
 190 int viopath_isactive(HvLpIndex lp)
 191 {
 192         if (lp == HvLpIndexInvalid)
 193                 return 0;
 194         if (lp < HVMAXARCHITECTEDLPS)
 195                 return viopathStatus[lp].isActive;
 196         else
 197                 return 0;
 198 }
 199 EXPORT_SYMBOL(viopath_isactive);
 200
 201 /*
 202  * We cache the source and target instance ids for each
 203  * partition.
 204  */
 205 HvLpInstanceId viopath_sourceinst(HvLpIndex lp)
 206 {
 207         return viopathStatus[lp].mSourceInst;
 208 }
 209 EXPORT_SYMBOL(viopath_sourceinst);
 210
 211 HvLpInstanceId viopath_targetinst(HvLpIndex lp)
 212 {
 213         return viopathStatus[lp].mTargetInst;
 214 }
 215 EXPORT_SYMBOL(viopath_targetinst);
 216
 217 /*
 218  * Send a monitor message.  This is a message with the acknowledge
 219  * bit on that the other side will NOT explicitly acknowledge.  When
 220  * the other side goes down, the hypervisor will acknowledge any
 221  * outstanding messages....so we will know when the other side dies.
 222  */
 223 static void sendMonMsg(HvLpIndex remoteLp)
 224 {
 225         HvLpEvent_Rc hvrc;
 226
 227         viopathStatus[remoteLp].mSourceInst =
 228                 HvCallEvent_getSourceLpInstanceId(remoteLp,
 229                                 HvLpEvent_Type_VirtualIo);
 230         viopathStatus[remoteLp].mTargetInst =
 231                 HvCallEvent_getTargetLpInstanceId(remoteLp,
 232                                 HvLpEvent_Type_VirtualIo);
 233
 234         /*
 235          * Deliberately ignore the return code here.  if we call this
 236          * more than once, we don't care.
 237          */
 238         vio_setHandler(viomajorsubtype_monitor, handleMonitorEvent);
 239
 240         hvrc = HvCallEvent_signalLpEventFast(remoteLp, HvLpEvent_Type_VirtualIo,
 241                         viomajorsubtype_monitor, HvLpEvent_AckInd_DoAck,
 242                         HvLpEvent_AckType_DeferredAck,
 243                         viopathStatus[remoteLp].mSourceInst,
 244                         viopathStatus[remoteLp].mTargetInst,
 245                         viomonseq++, 0, 0, 0, 0, 0);
 246
 247         if (hvrc == HvLpEvent_Rc_Good)
 248                 viopathStatus[remoteLp].isActive = 1;
 249         else {
 250                 printk(VIOPATH_KERN_WARN "could not connect to partition %d\n",
 251                                 remoteLp);
 252                 viopathStatus[remoteLp].isActive = 0;
 253         }
 254 }
 255
 256 static void handleMonitorEvent(struct HvLpEvent *event)
 257 {
 258         HvLpIndex remoteLp;
 259         int i;
 260
 261         /*
 262          * This handler is _also_ called as part of the loop
 263          * at the end of this routine, so it must be able to
 264          * ignore NULL events...
 265          */
 266         if (!event)
 267                 return;
 268
 269         /*
 270          * First see if this is just a normal monitor message from the
 271          * other partition
 272          */
 273         if (hvlpevent_is_int(event)) {
 274                 remoteLp = event->xSourceLp;
 275                 if (!viopathStatus[remoteLp].isActive)
 276                         sendMonMsg(remoteLp);
 277                 return;
 278         }
 279
 280         /*
 281          * This path is for an acknowledgement; the other partition
 282          * died
 283          */
 284         remoteLp = event->xTargetLp;
 285         if ((event->xSourceInstanceId != viopathStatus[remoteLp].mSourceInst) ||
 286             (event->xTargetInstanceId != viopathStatus[remoteLp].mTargetInst)) {
 287                 printk(VIOPATH_KERN_WARN "ignoring ack....mismatched instances\n");
 288                 return;
 289         }
 290
 291         printk(VIOPATH_KERN_WARN "partition %d ended\n", remoteLp);
 292
 293         viopathStatus[remoteLp].isActive = 0;
 294
 295         /*
 296          * For each active handler, pass them a NULL
 297          * message to indicate that the other partition
 298          * died
 299          */
 300         for (i = 0; i < VIO_MAX_SUBTYPES; i++) {
 301                 if (vio_handler[i] != NULL)
 302                         (*vio_handler[i])(NULL);
 303         }
 304 }
 305
 306 int vio_setHandler(int subtype, vio_event_handler_t *beh)
 307 {
 308         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 309         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 310                 return -EINVAL;
 311         if (vio_handler[subtype] != NULL)
 312                 return -EBUSY;
 313         vio_handler[subtype] = beh;
 314         return 0;
 315 }
 316 EXPORT_SYMBOL(vio_setHandler);
 317
 318 int vio_clearHandler(int subtype)
 319 {
 320         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 321         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 322                 return -EINVAL;
 323         if (vio_handler[subtype] == NULL)
 324                 return -EAGAIN;
 325         vio_handler[subtype] = NULL;
 326         return 0;
 327 }
 328 EXPORT_SYMBOL(vio_clearHandler);
 329
 330 static void handleConfig(struct HvLpEvent *event)
 331 {
 332         if (!event)
 333                 return;
 334         if (hvlpevent_is_int(event)) {
 335                 printk(VIOPATH_KERN_WARN
 336                        "unexpected config request from partition %d",
 337                        event->xSourceLp);
 338
 339                 if (hvlpevent_need_ack(event)) {
 340                         event->xRc = HvLpEvent_Rc_InvalidSubtype;
 341                         HvCallEvent_ackLpEvent(event);
 342                 }
 343                 return;
 344         }
 345
 346         up((struct semaphore *)event->xCorrelationToken);
 347 }
 348
 349 /*
 350  * Initialization of the hosting partition
 351  */
 352 void vio_set_hostlp(void)
 353 {
 354         /*
 355          * If this has already been set then we DON'T want to either change
 356          * it or re-register the proc file system
 357          */
 358         if (viopath_hostLp != HvLpIndexInvalid)
 359                 return;
 360
 361         /*
 362          * Figure out our hosting partition.  This isn't allowed to change
 363          * while we're active
 364          */
 365         viopath_ourLp = HvLpConfig_getLpIndex();
 366         viopath_hostLp = HvLpConfig_getHostingLpIndex(viopath_ourLp);
 367
 368         if (viopath_hostLp != HvLpIndexInvalid)
 369                 vio_setHandler(viomajorsubtype_config, handleConfig);
 370 }
 371 EXPORT_SYMBOL(vio_set_hostlp);
 372
 373 static void vio_handleEvent(struct HvLpEvent *event, struct pt_regs *regs)
 374 {
 375         HvLpIndex remoteLp;
 376         int subtype = (event->xSubtype & VIOMAJOR_SUBTYPE_MASK)
 377                 >> VIOMAJOR_SUBTYPE_SHIFT;
 378
 379         if (hvlpevent_is_int(event)) {
 380                 remoteLp = event->xSourceLp;
 381                 /*
 382                  * The isActive is checked because if the hosting partition
 383                  * went down and came back up it would not be active but it
 384                  * would have different source and target instances, in which
 385                  * case we'd want to reset them.  This case really protects
 386                  * against an unauthorized active partition sending interrupts
 387                  * or acks to this linux partition.
 388                  */
 389                 if (viopathStatus[remoteLp].isActive
 390                     && (event->xSourceInstanceId !=
 391                         viopathStatus[remoteLp].mTargetInst)) {
 392                         printk(VIOPATH_KERN_WARN
 393                                "message from invalid partition. "
 394                                "int msg rcvd, source inst (%d) doesnt match (%d)\n",
 395                                viopathStatus[remoteLp].mTargetInst,
 396                                event->xSourceInstanceId);
 397                         return;
 398                 }
 399
 400                 if (viopathStatus[remoteLp].isActive
 401                     && (event->xTargetInstanceId !=
 402                         viopathStatus[remoteLp].mSourceInst)) {
 403                         printk(VIOPATH_KERN_WARN
 404                                "message from invalid partition. "
 405                                "int msg rcvd, target inst (%d) doesnt match (%d)\n",
 406                                viopathStatus[remoteLp].mSourceInst,
 407                                event->xTargetInstanceId);
 408                         return;
 409                 }
 410         } else {
 411                 remoteLp = event->xTargetLp;
 412                 if (event->xSourceInstanceId !=
 413                     viopathStatus[remoteLp].mSourceInst) {
 414                         printk(VIOPATH_KERN_WARN
 415                                "message from invalid partition. "
 416                                "ack msg rcvd, source inst (%d) doesnt match (%d)\n",
 417                                viopathStatus[remoteLp].mSourceInst,
 418                                event->xSourceInstanceId);
 419                         return;
 420                 }
 421
 422                 if (event->xTargetInstanceId !=
 423                     viopathStatus[remoteLp].mTargetInst) {
 424                         printk(VIOPATH_KERN_WARN
 425                                "message from invalid partition. "
 426                                "viopath: ack msg rcvd, target inst (%d) doesnt match (%d)\n",
 427                                viopathStatus[remoteLp].mTargetInst,
 428                                event->xTargetInstanceId);
 429                         return;
 430                 }
 431         }
 432
 433         if (vio_handler[subtype] == NULL) {
 434                 printk(VIOPATH_KERN_WARN
 435                        "unexpected virtual io event subtype %d from partition %d\n",
 436                        event->xSubtype, remoteLp);
 437                 /* No handler.  Ack if necessary */
 438                 if (hvlpevent_is_int(event) && hvlpevent_need_ack(event)) {
 439                         event->xRc = HvLpEvent_Rc_InvalidSubtype;
 440                         HvCallEvent_ackLpEvent(event);
 441                 }
 442                 return;
 443         }
 444
 445         /* This innocuous little line is where all the real work happens */
 446         (*vio_handler[subtype])(event);
 447 }
 448
 449 static void viopath_donealloc(void *parm, int number)
 450 {
 451         struct alloc_parms *parmsp = parm;
 452
 453         parmsp->number = number;
 454         if (parmsp->used_wait_atomic)
 455                 atomic_set(&parmsp->wait_atomic, 0);
 456         else
 457                 up(&parmsp->sem);
 458 }
 459
 460 static int allocateEvents(HvLpIndex remoteLp, int numEvents)
 461 {
 462         struct alloc_parms parms;
 463
 464         if (system_state != SYSTEM_RUNNING) {
 465                 parms.used_wait_atomic = 1;
 466                 atomic_set(&parms.wait_atomic, 1);
 467         } else {
 468                 parms.used_wait_atomic = 0;
 469                 init_MUTEX_LOCKED(&parms.sem);
 470         }
 471         mf_allocate_lp_events(remoteLp, HvLpEvent_Type_VirtualIo, 250,  /* It would be nice to put a real number here! */
 472                             numEvents, &viopath_donealloc, &parms);
 473         if (system_state != SYSTEM_RUNNING) {
 474                 while (atomic_read(&parms.wait_atomic))
 475                         mb();
 476         } else
 477                 down(&parms.sem);
 478         return parms.number;
 479 }
 480
 481 int viopath_open(HvLpIndex remoteLp, int subtype, int numReq)
 482 {
 483         int i;
 484         unsigned long flags;
 485         int tempNumAllocated;
 486
 487         if ((remoteLp >= HVMAXARCHITECTEDLPS) || (remoteLp == HvLpIndexInvalid))
 488                 return -EINVAL;
 489
 490         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 491         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 492                 return -EINVAL;
 493
 494         spin_lock_irqsave(&statuslock, flags);
 495
 496         if (!event_buffer_initialised) {
 497                 for (i = 0; i < VIO_MAX_SUBTYPES; i++)
 498                         atomic_set(&event_buffer_available[i], 1);
 499                 event_buffer_initialised = 1;
 500         }
 501
 502         viopathStatus[remoteLp].users[subtype]++;
 503
 504         if (!viopathStatus[remoteLp].isOpen) {
 505                 viopathStatus[remoteLp].isOpen = 1;
 506                 HvCallEvent_openLpEventPath(remoteLp, HvLpEvent_Type_VirtualIo);
 507
 508                 /*
 509                  * Don't hold the spinlock during an operation that
 510                  * can sleep.
 511                  */
 512                 spin_unlock_irqrestore(&statuslock, flags);
 513                 tempNumAllocated = allocateEvents(remoteLp, 1);
 514                 spin_lock_irqsave(&statuslock, flags);
 515
 516                 viopathStatus[remoteLp].numberAllocated += tempNumAllocated;
 517
 518                 if (viopathStatus[remoteLp].numberAllocated == 0) {
 519                         HvCallEvent_closeLpEventPath(remoteLp,
 520                                         HvLpEvent_Type_VirtualIo);
 521
 522                         spin_unlock_irqrestore(&statuslock, flags);
 523                         return -ENOMEM;
 524                 }
 525
 526                 viopathStatus[remoteLp].mSourceInst =
 527                         HvCallEvent_getSourceLpInstanceId(remoteLp,
 528                                         HvLpEvent_Type_VirtualIo);
 529                 viopathStatus[remoteLp].mTargetInst =
 530                         HvCallEvent_getTargetLpInstanceId(remoteLp,
 531                                         HvLpEvent_Type_VirtualIo);
 532                 HvLpEvent_registerHandler(HvLpEvent_Type_VirtualIo,
 533                                           &vio_handleEvent);
 534                 sendMonMsg(remoteLp);
 535                 printk(VIOPATH_KERN_INFO "opening connection to partition %d, "
 536                                 "setting sinst %d, tinst %d\n",
 537                                 remoteLp, viopathStatus[remoteLp].mSourceInst,
 538                                 viopathStatus[remoteLp].mTargetInst);
 539         }
 540
 541         spin_unlock_irqrestore(&statuslock, flags);
 542         tempNumAllocated = allocateEvents(remoteLp, numReq);
 543         spin_lock_irqsave(&statuslock, flags);
 544         viopathStatus[remoteLp].numberAllocated += tempNumAllocated;
 545         spin_unlock_irqrestore(&statuslock, flags);
 546
 547         return 0;
 548 }
 549 EXPORT_SYMBOL(viopath_open);
 550
 551 int viopath_close(HvLpIndex remoteLp, int subtype, int numReq)
 552 {
 553         unsigned long flags;
 554         int i;
 555         int numOpen;
 556         struct alloc_parms parms;
 557
 558         if ((remoteLp >= HVMAXARCHITECTEDLPS) || (remoteLp == HvLpIndexInvalid))
 559                 return -EINVAL;
 560
 561         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 562         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 563                 return -EINVAL;
 564
 565         spin_lock_irqsave(&statuslock, flags);
 566         /*
 567          * If the viopath_close somehow gets called before a
 568          * viopath_open it could decrement to -1 which is a non
 569          * recoverable state so we'll prevent this from
 570          * happening.
 571          */
 572         if (viopathStatus[remoteLp].users[subtype] > 0)
 573                 viopathStatus[remoteLp].users[subtype]--;
 574
 575         spin_unlock_irqrestore(&statuslock, flags);
 576
 577         parms.used_wait_atomic = 0;
 578         init_MUTEX_LOCKED(&parms.sem);
 579         mf_deallocate_lp_events(remoteLp, HvLpEvent_Type_VirtualIo,
 580                               numReq, &viopath_donealloc, &parms);
 581         down(&parms.sem);
 582
 583         spin_lock_irqsave(&statuslock, flags);
 584         for (i = 0, numOpen = 0; i < VIO_MAX_SUBTYPES; i++)
 585                 numOpen += viopathStatus[remoteLp].users[i];
 586
 587         if ((viopathStatus[remoteLp].isOpen) && (numOpen == 0)) {
 588                 printk(VIOPATH_KERN_INFO "closing connection to partition %d",
 589                                 remoteLp);
 590
 591                 HvCallEvent_closeLpEventPath(remoteLp,
 592                                              HvLpEvent_Type_VirtualIo);
 593                 viopathStatus[remoteLp].isOpen = 0;
 594                 viopathStatus[remoteLp].isActive = 0;
 595
 596                 for (i = 0; i < VIO_MAX_SUBTYPES; i++)
 597                         atomic_set(&event_buffer_available[i], 0);
 598                 event_buffer_initialised = 0;
 599         }
 600         spin_unlock_irqrestore(&statuslock, flags);
 601         return 0;
 602 }
 603 EXPORT_SYMBOL(viopath_close);
 604
 605 void *vio_get_event_buffer(int subtype)
 606 {
 607         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 608         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 609                 return NULL;
 610
 611         if (atomic_dec_if_positive(&event_buffer_available[subtype]) == 0)
 612                 return &event_buffer[subtype * 256];
 613         else
 614                 return NULL;
 615 }
 616 EXPORT_SYMBOL(vio_get_event_buffer);
 617
 618 void vio_free_event_buffer(int subtype, void *buffer)
 619 {
 620         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 621         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES)) {
 622                 printk(VIOPATH_KERN_WARN
 623                        "unexpected subtype %d freeing event buffer\n", subtype);
 624                 return;
 625         }
 626
 627         if (atomic_read(&event_buffer_available[subtype]) != 0) {
 628                 printk(VIOPATH_KERN_WARN
 629                        "freeing unallocated event buffer, subtype %d\n",
 630                        subtype);
 631                 return;
 632         }
 633
 634         if (buffer != &event_buffer[subtype * 256]) {
 635                 printk(VIOPATH_KERN_WARN
 636                        "freeing invalid event buffer, subtype %d\n", subtype);
 637         }
 638
 639         atomic_set(&event_buffer_available[subtype], 1);
 640 }
 641 EXPORT_SYMBOL(vio_free_event_buffer);
 642
 643 static const struct vio_error_entry vio_no_error =
 644     { 0, 0, "Non-VIO Error" };
 645 static const struct vio_error_entry vio_unknown_error =
 646     { 0, EIO, "Unknown Error" };
 647
 648 static const struct vio_error_entry vio_default_errors[] = {
 649         {0x0001, EIO, "No Connection"},
 650         {0x0002, EIO, "No Receiver"},
 651         {0x0003, EIO, "No Buffer Available"},
 652         {0x0004, EBADRQC, "Invalid Message Type"},
 653         {0x0000, 0, NULL},
 654 };
 655
 656 const struct vio_error_entry *vio_lookup_rc(
 657                 const struct vio_error_entry *local_table, u16 rc)
 658 {
 659         const struct vio_error_entry *cur;
 660
 661         if (!rc)
 662                 return &vio_no_error;
 663         if (local_table)
 664                 for (cur = local_table; cur->rc; ++cur)
 665                         if (cur->rc == rc)
 666                                 return cur;
 667         for (cur = vio_default_errors; cur->rc; ++cur)
 668                 if (cur->rc == rc)
 669                         return cur;
 670         return &vio_unknown_error;
 671 }
 672 EXPORT_SYMBOL(vio_lookup_rc);