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/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 = 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 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         e = create_proc_entry("iSeries/config", 0, NULL);
 187         if (e)
 188                 e->proc_fops = &proc_viopath_operations;
 189
 190         return 0;
 191 }
 192 __initcall(vio_proc_init);
 193
 194 /* See if a given LP is active.  Allow for invalid lps to be passed in
 195  * and just return invalid
 196  */
 197 int viopath_isactive(HvLpIndex lp)
 198 {
 199         if (lp == HvLpIndexInvalid)
 200                 return 0;
 201         if (lp < HVMAXARCHITECTEDLPS)
 202                 return viopathStatus[lp].isActive;
 203         else
 204                 return 0;
 205 }
 206 EXPORT_SYMBOL(viopath_isactive);
 207
 208 /*
 209  * We cache the source and target instance ids for each
 210  * partition.
 211  */
 212 HvLpInstanceId viopath_sourceinst(HvLpIndex lp)
 213 {
 214         return viopathStatus[lp].mSourceInst;
 215 }
 216 EXPORT_SYMBOL(viopath_sourceinst);
 217
 218 HvLpInstanceId viopath_targetinst(HvLpIndex lp)
 219 {
 220         return viopathStatus[lp].mTargetInst;
 221 }
 222 EXPORT_SYMBOL(viopath_targetinst);
 223
 224 /*
 225  * Send a monitor message.  This is a message with the acknowledge
 226  * bit on that the other side will NOT explicitly acknowledge.  When
 227  * the other side goes down, the hypervisor will acknowledge any
 228  * outstanding messages....so we will know when the other side dies.
 229  */
 230 static void sendMonMsg(HvLpIndex remoteLp)
 231 {
 232         HvLpEvent_Rc hvrc;
 233
 234         viopathStatus[remoteLp].mSourceInst =
 235                 HvCallEvent_getSourceLpInstanceId(remoteLp,
 236                                 HvLpEvent_Type_VirtualIo);
 237         viopathStatus[remoteLp].mTargetInst =
 238                 HvCallEvent_getTargetLpInstanceId(remoteLp,
 239                                 HvLpEvent_Type_VirtualIo);
 240
 241         /*
 242          * Deliberately ignore the return code here.  if we call this
 243          * more than once, we don't care.
 244          */
 245         vio_setHandler(viomajorsubtype_monitor, handleMonitorEvent);
 246
 247         hvrc = HvCallEvent_signalLpEventFast(remoteLp, HvLpEvent_Type_VirtualIo,
 248                         viomajorsubtype_monitor, HvLpEvent_AckInd_DoAck,
 249                         HvLpEvent_AckType_DeferredAck,
 250                         viopathStatus[remoteLp].mSourceInst,
 251                         viopathStatus[remoteLp].mTargetInst,
 252                         viomonseq++, 0, 0, 0, 0, 0);
 253
 254         if (hvrc == HvLpEvent_Rc_Good)
 255                 viopathStatus[remoteLp].isActive = 1;
 256         else {
 257                 printk(VIOPATH_KERN_WARN "could not connect to partition %d\n",
 258                                 remoteLp);
 259                 viopathStatus[remoteLp].isActive = 0;
 260         }
 261 }
 262
 263 static void handleMonitorEvent(struct HvLpEvent *event)
 264 {
 265         HvLpIndex remoteLp;
 266         int i;
 267
 268         /*
 269          * This handler is _also_ called as part of the loop
 270          * at the end of this routine, so it must be able to
 271          * ignore NULL events...
 272          */
 273         if (!event)
 274                 return;
 275
 276         /*
 277          * First see if this is just a normal monitor message from the
 278          * other partition
 279          */
 280         if (hvlpevent_is_int(event)) {
 281                 remoteLp = event->xSourceLp;
 282                 if (!viopathStatus[remoteLp].isActive)
 283                         sendMonMsg(remoteLp);
 284                 return;
 285         }
 286
 287         /*
 288          * This path is for an acknowledgement; the other partition
 289          * died
 290          */
 291         remoteLp = event->xTargetLp;
 292         if ((event->xSourceInstanceId != viopathStatus[remoteLp].mSourceInst) ||
 293             (event->xTargetInstanceId != viopathStatus[remoteLp].mTargetInst)) {
 294                 printk(VIOPATH_KERN_WARN "ignoring ack....mismatched instances\n");
 295                 return;
 296         }
 297
 298         printk(VIOPATH_KERN_WARN "partition %d ended\n", remoteLp);
 299
 300         viopathStatus[remoteLp].isActive = 0;
 301
 302         /*
 303          * For each active handler, pass them a NULL
 304          * message to indicate that the other partition
 305          * died
 306          */
 307         for (i = 0; i < VIO_MAX_SUBTYPES; i++) {
 308                 if (vio_handler[i] != NULL)
 309                         (*vio_handler[i])(NULL);
 310         }
 311 }
 312
 313 int vio_setHandler(int subtype, vio_event_handler_t *beh)
 314 {
 315         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 316         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 317                 return -EINVAL;
 318         if (vio_handler[subtype] != NULL)
 319                 return -EBUSY;
 320         vio_handler[subtype] = beh;
 321         return 0;
 322 }
 323 EXPORT_SYMBOL(vio_setHandler);
 324
 325 int vio_clearHandler(int subtype)
 326 {
 327         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 328         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 329                 return -EINVAL;
 330         if (vio_handler[subtype] == NULL)
 331                 return -EAGAIN;
 332         vio_handler[subtype] = NULL;
 333         return 0;
 334 }
 335 EXPORT_SYMBOL(vio_clearHandler);
 336
 337 static void handleConfig(struct HvLpEvent *event)
 338 {
 339         if (!event)
 340                 return;
 341         if (hvlpevent_is_int(event)) {
 342                 printk(VIOPATH_KERN_WARN
 343                        "unexpected config request from partition %d",
 344                        event->xSourceLp);
 345
 346                 if (hvlpevent_need_ack(event)) {
 347                         event->xRc = HvLpEvent_Rc_InvalidSubtype;
 348                         HvCallEvent_ackLpEvent(event);
 349                 }
 350                 return;
 351         }
 352
 353         up((struct semaphore *)event->xCorrelationToken);
 354 }
 355
 356 /*
 357  * Initialization of the hosting partition
 358  */
 359 void vio_set_hostlp(void)
 360 {
 361         /*
 362          * If this has already been set then we DON'T want to either change
 363          * it or re-register the proc file system
 364          */
 365         if (viopath_hostLp != HvLpIndexInvalid)
 366                 return;
 367
 368         /*
 369          * Figure out our hosting partition.  This isn't allowed to change
 370          * while we're active
 371          */
 372         viopath_ourLp = HvLpConfig_getLpIndex();
 373         viopath_hostLp = HvLpConfig_getHostingLpIndex(viopath_ourLp);
 374
 375         if (viopath_hostLp != HvLpIndexInvalid)
 376                 vio_setHandler(viomajorsubtype_config, handleConfig);
 377 }
 378 EXPORT_SYMBOL(vio_set_hostlp);
 379
 380 static void vio_handleEvent(struct HvLpEvent *event)
 381 {
 382         HvLpIndex remoteLp;
 383         int subtype = (event->xSubtype & VIOMAJOR_SUBTYPE_MASK)
 384                 >> VIOMAJOR_SUBTYPE_SHIFT;
 385
 386         if (hvlpevent_is_int(event)) {
 387                 remoteLp = event->xSourceLp;
 388                 /*
 389                  * The isActive is checked because if the hosting partition
 390                  * went down and came back up it would not be active but it
 391                  * would have different source and target instances, in which
 392                  * case we'd want to reset them.  This case really protects
 393                  * against an unauthorized active partition sending interrupts
 394                  * or acks to this linux partition.
 395                  */
 396                 if (viopathStatus[remoteLp].isActive
 397                     && (event->xSourceInstanceId !=
 398                         viopathStatus[remoteLp].mTargetInst)) {
 399                         printk(VIOPATH_KERN_WARN
 400                                "message from invalid partition. "
 401                                "int msg rcvd, source inst (%d) doesnt match (%d)\n",
 402                                viopathStatus[remoteLp].mTargetInst,
 403                                event->xSourceInstanceId);
 404                         return;
 405                 }
 406
 407                 if (viopathStatus[remoteLp].isActive
 408                     && (event->xTargetInstanceId !=
 409                         viopathStatus[remoteLp].mSourceInst)) {
 410                         printk(VIOPATH_KERN_WARN
 411                                "message from invalid partition. "
 412                                "int msg rcvd, target inst (%d) doesnt match (%d)\n",
 413                                viopathStatus[remoteLp].mSourceInst,
 414                                event->xTargetInstanceId);
 415                         return;
 416                 }
 417         } else {
 418                 remoteLp = event->xTargetLp;
 419                 if (event->xSourceInstanceId !=
 420                     viopathStatus[remoteLp].mSourceInst) {
 421                         printk(VIOPATH_KERN_WARN
 422                                "message from invalid partition. "
 423                                "ack msg rcvd, source inst (%d) doesnt match (%d)\n",
 424                                viopathStatus[remoteLp].mSourceInst,
 425                                event->xSourceInstanceId);
 426                         return;
 427                 }
 428
 429                 if (event->xTargetInstanceId !=
 430                     viopathStatus[remoteLp].mTargetInst) {
 431                         printk(VIOPATH_KERN_WARN
 432                                "message from invalid partition. "
 433                                "viopath: ack msg rcvd, target inst (%d) doesnt match (%d)\n",
 434                                viopathStatus[remoteLp].mTargetInst,
 435                                event->xTargetInstanceId);
 436                         return;
 437                 }
 438         }
 439
 440         if (vio_handler[subtype] == NULL) {
 441                 printk(VIOPATH_KERN_WARN
 442                        "unexpected virtual io event subtype %d from partition %d\n",
 443                        event->xSubtype, remoteLp);
 444                 /* No handler.  Ack if necessary */
 445                 if (hvlpevent_is_int(event) && hvlpevent_need_ack(event)) {
 446                         event->xRc = HvLpEvent_Rc_InvalidSubtype;
 447                         HvCallEvent_ackLpEvent(event);
 448                 }
 449                 return;
 450         }
 451
 452         /* This innocuous little line is where all the real work happens */
 453         (*vio_handler[subtype])(event);
 454 }
 455
 456 static void viopath_donealloc(void *parm, int number)
 457 {
 458         struct alloc_parms *parmsp = parm;
 459
 460         parmsp->number = number;
 461         if (parmsp->used_wait_atomic)
 462                 atomic_set(&parmsp->wait_atomic, 0);
 463         else
 464                 up(&parmsp->sem);
 465 }
 466
 467 static int allocateEvents(HvLpIndex remoteLp, int numEvents)
 468 {
 469         struct alloc_parms parms;
 470
 471         if (system_state != SYSTEM_RUNNING) {
 472                 parms.used_wait_atomic = 1;
 473                 atomic_set(&parms.wait_atomic, 1);
 474         } else {
 475                 parms.used_wait_atomic = 0;
 476                 init_MUTEX_LOCKED(&parms.sem);
 477         }
 478         mf_allocate_lp_events(remoteLp, HvLpEvent_Type_VirtualIo, 250,  /* It would be nice to put a real number here! */
 479                             numEvents, &viopath_donealloc, &parms);
 480         if (system_state != SYSTEM_RUNNING) {
 481                 while (atomic_read(&parms.wait_atomic))
 482                         mb();
 483         } else
 484                 down(&parms.sem);
 485         return parms.number;
 486 }
 487
 488 int viopath_open(HvLpIndex remoteLp, int subtype, int numReq)
 489 {
 490         int i;
 491         unsigned long flags;
 492         int tempNumAllocated;
 493
 494         if ((remoteLp >= HVMAXARCHITECTEDLPS) || (remoteLp == HvLpIndexInvalid))
 495                 return -EINVAL;
 496
 497         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 498         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 499                 return -EINVAL;
 500
 501         spin_lock_irqsave(&statuslock, flags);
 502
 503         if (!event_buffer_initialised) {
 504                 for (i = 0; i < VIO_MAX_SUBTYPES; i++)
 505                         atomic_set(&event_buffer_available[i], 1);
 506                 event_buffer_initialised = 1;
 507         }
 508
 509         viopathStatus[remoteLp].users[subtype]++;
 510
 511         if (!viopathStatus[remoteLp].isOpen) {
 512                 viopathStatus[remoteLp].isOpen = 1;
 513                 HvCallEvent_openLpEventPath(remoteLp, HvLpEvent_Type_VirtualIo);
 514
 515                 /*
 516                  * Don't hold the spinlock during an operation that
 517                  * can sleep.
 518                  */
 519                 spin_unlock_irqrestore(&statuslock, flags);
 520                 tempNumAllocated = allocateEvents(remoteLp, 1);
 521                 spin_lock_irqsave(&statuslock, flags);
 522
 523                 viopathStatus[remoteLp].numberAllocated += tempNumAllocated;
 524
 525                 if (viopathStatus[remoteLp].numberAllocated == 0) {
 526                         HvCallEvent_closeLpEventPath(remoteLp,
 527                                         HvLpEvent_Type_VirtualIo);
 528
 529                         spin_unlock_irqrestore(&statuslock, flags);
 530                         return -ENOMEM;
 531                 }
 532
 533                 viopathStatus[remoteLp].mSourceInst =
 534                         HvCallEvent_getSourceLpInstanceId(remoteLp,
 535                                         HvLpEvent_Type_VirtualIo);
 536                 viopathStatus[remoteLp].mTargetInst =
 537                         HvCallEvent_getTargetLpInstanceId(remoteLp,
 538                                         HvLpEvent_Type_VirtualIo);
 539                 HvLpEvent_registerHandler(HvLpEvent_Type_VirtualIo,
 540                                           &vio_handleEvent);
 541                 sendMonMsg(remoteLp);
 542                 printk(VIOPATH_KERN_INFO "opening connection to partition %d, "
 543                                 "setting sinst %d, tinst %d\n",
 544                                 remoteLp, viopathStatus[remoteLp].mSourceInst,
 545                                 viopathStatus[remoteLp].mTargetInst);
 546         }
 547
 548         spin_unlock_irqrestore(&statuslock, flags);
 549         tempNumAllocated = allocateEvents(remoteLp, numReq);
 550         spin_lock_irqsave(&statuslock, flags);
 551         viopathStatus[remoteLp].numberAllocated += tempNumAllocated;
 552         spin_unlock_irqrestore(&statuslock, flags);
 553
 554         return 0;
 555 }
 556 EXPORT_SYMBOL(viopath_open);
 557
 558 int viopath_close(HvLpIndex remoteLp, int subtype, int numReq)
 559 {
 560         unsigned long flags;
 561         int i;
 562         int numOpen;
 563         struct alloc_parms parms;
 564
 565         if ((remoteLp >= HVMAXARCHITECTEDLPS) || (remoteLp == HvLpIndexInvalid))
 566                 return -EINVAL;
 567
 568         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 569         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 570                 return -EINVAL;
 571
 572         spin_lock_irqsave(&statuslock, flags);
 573         /*
 574          * If the viopath_close somehow gets called before a
 575          * viopath_open it could decrement to -1 which is a non
 576          * recoverable state so we'll prevent this from
 577          * happening.
 578          */
 579         if (viopathStatus[remoteLp].users[subtype] > 0)
 580                 viopathStatus[remoteLp].users[subtype]--;
 581
 582         spin_unlock_irqrestore(&statuslock, flags);
 583
 584         parms.used_wait_atomic = 0;
 585         init_MUTEX_LOCKED(&parms.sem);
 586         mf_deallocate_lp_events(remoteLp, HvLpEvent_Type_VirtualIo,
 587                               numReq, &viopath_donealloc, &parms);
 588         down(&parms.sem);
 589
 590         spin_lock_irqsave(&statuslock, flags);
 591         for (i = 0, numOpen = 0; i < VIO_MAX_SUBTYPES; i++)
 592                 numOpen += viopathStatus[remoteLp].users[i];
 593
 594         if ((viopathStatus[remoteLp].isOpen) && (numOpen == 0)) {
 595                 printk(VIOPATH_KERN_INFO "closing connection to partition %d",
 596                                 remoteLp);
 597
 598                 HvCallEvent_closeLpEventPath(remoteLp,
 599                                              HvLpEvent_Type_VirtualIo);
 600                 viopathStatus[remoteLp].isOpen = 0;
 601                 viopathStatus[remoteLp].isActive = 0;
 602
 603                 for (i = 0; i < VIO_MAX_SUBTYPES; i++)
 604                         atomic_set(&event_buffer_available[i], 0);
 605                 event_buffer_initialised = 0;
 606         }
 607         spin_unlock_irqrestore(&statuslock, flags);
 608         return 0;
 609 }
 610 EXPORT_SYMBOL(viopath_close);
 611
 612 void *vio_get_event_buffer(int subtype)
 613 {
 614         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 615         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 616                 return NULL;
 617
 618         if (atomic_dec_if_positive(&event_buffer_available[subtype]) == 0)
 619                 return &event_buffer[subtype * 256];
 620         else
 621                 return NULL;
 622 }
 623 EXPORT_SYMBOL(vio_get_event_buffer);
 624
 625 void vio_free_event_buffer(int subtype, void *buffer)
 626 {
 627         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 628         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES)) {
 629                 printk(VIOPATH_KERN_WARN
 630                        "unexpected subtype %d freeing event buffer\n", subtype);
 631                 return;
 632         }
 633
 634         if (atomic_read(&event_buffer_available[subtype]) != 0) {
 635                 printk(VIOPATH_KERN_WARN
 636                        "freeing unallocated event buffer, subtype %d\n",
 637                        subtype);
 638                 return;
 639         }
 640
 641         if (buffer != &event_buffer[subtype * 256]) {
 642                 printk(VIOPATH_KERN_WARN
 643                        "freeing invalid event buffer, subtype %d\n", subtype);
 644         }
 645
 646         atomic_set(&event_buffer_available[subtype], 1);
 647 }
 648 EXPORT_SYMBOL(vio_free_event_buffer);
 649
 650 static const struct vio_error_entry vio_no_error =
 651     { 0, 0, "Non-VIO Error" };
 652 static const struct vio_error_entry vio_unknown_error =
 653     { 0, EIO, "Unknown Error" };
 654
 655 static const struct vio_error_entry vio_default_errors[] = {
 656         {0x0001, EIO, "No Connection"},
 657         {0x0002, EIO, "No Receiver"},
 658         {0x0003, EIO, "No Buffer Available"},
 659         {0x0004, EBADRQC, "Invalid Message Type"},
 660         {0x0000, 0, NULL},
 661 };
 662
 663 const struct vio_error_entry *vio_lookup_rc(
 664                 const struct vio_error_entry *local_table, u16 rc)
 665 {
 666         const struct vio_error_entry *cur;
 667
 668         if (!rc)
 669                 return &vio_no_error;
 670         if (local_table)
 671                 for (cur = local_table; cur->rc; ++cur)
 672                         if (cur->rc == rc)
 673                                 return cur;
 674         for (cur = vio_default_errors; cur->rc; ++cur)
 675                 if (cur->rc == rc)
 676                         return cur;
 677         return &vio_unknown_error;
 678 }
 679 EXPORT_SYMBOL(vio_lookup_rc);