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