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(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         struct proc_dir_entry *e;
 184
 185         if (!firmware_has_feature(FW_FEATURE_ISERIES))
 186                 return 0;
 187
 188         e = create_proc_entry("iSeries/config", 0, NULL);
 189         if (e)
 190                 e->proc_fops = &proc_viopath_operations;
 191
 192         return 0;
 193 }
 194 __initcall(vio_proc_init);
 195
 196 /* See if a given LP is active.  Allow for invalid lps to be passed in
 197  * and just return invalid
 198  */
 199 int viopath_isactive(HvLpIndex lp)
 200 {
 201         if (lp == HvLpIndexInvalid)
 202                 return 0;
 203         if (lp < HVMAXARCHITECTEDLPS)
 204                 return viopathStatus[lp].isActive;
 205         else
 206                 return 0;
 207 }
 208 EXPORT_SYMBOL(viopath_isactive);
 209
 210 /*
 211  * We cache the source and target instance ids for each
 212  * partition.
 213  */
 214 HvLpInstanceId viopath_sourceinst(HvLpIndex lp)
 215 {
 216         return viopathStatus[lp].mSourceInst;
 217 }
 218 EXPORT_SYMBOL(viopath_sourceinst);
 219
 220 HvLpInstanceId viopath_targetinst(HvLpIndex lp)
 221 {
 222         return viopathStatus[lp].mTargetInst;
 223 }
 224 EXPORT_SYMBOL(viopath_targetinst);
 225
 226 /*
 227  * Send a monitor message.  This is a message with the acknowledge
 228  * bit on that the other side will NOT explicitly acknowledge.  When
 229  * the other side goes down, the hypervisor will acknowledge any
 230  * outstanding messages....so we will know when the other side dies.
 231  */
 232 static void sendMonMsg(HvLpIndex remoteLp)
 233 {
 234         HvLpEvent_Rc hvrc;
 235
 236         viopathStatus[remoteLp].mSourceInst =
 237                 HvCallEvent_getSourceLpInstanceId(remoteLp,
 238                                 HvLpEvent_Type_VirtualIo);
 239         viopathStatus[remoteLp].mTargetInst =
 240                 HvCallEvent_getTargetLpInstanceId(remoteLp,
 241                                 HvLpEvent_Type_VirtualIo);
 242
 243         /*
 244          * Deliberately ignore the return code here.  if we call this
 245          * more than once, we don't care.
 246          */
 247         vio_setHandler(viomajorsubtype_monitor, handleMonitorEvent);
 248
 249         hvrc = HvCallEvent_signalLpEventFast(remoteLp, HvLpEvent_Type_VirtualIo,
 250                         viomajorsubtype_monitor, HvLpEvent_AckInd_DoAck,
 251                         HvLpEvent_AckType_DeferredAck,
 252                         viopathStatus[remoteLp].mSourceInst,
 253                         viopathStatus[remoteLp].mTargetInst,
 254                         viomonseq++, 0, 0, 0, 0, 0);
 255
 256         if (hvrc == HvLpEvent_Rc_Good)
 257                 viopathStatus[remoteLp].isActive = 1;
 258         else {
 259                 printk(VIOPATH_KERN_WARN "could not connect to partition %d\n",
 260                                 remoteLp);
 261                 viopathStatus[remoteLp].isActive = 0;
 262         }
 263 }
 264
 265 static void handleMonitorEvent(struct HvLpEvent *event)
 266 {
 267         HvLpIndex remoteLp;
 268         int i;
 269
 270         /*
 271          * This handler is _also_ called as part of the loop
 272          * at the end of this routine, so it must be able to
 273          * ignore NULL events...
 274          */
 275         if (!event)
 276                 return;
 277
 278         /*
 279          * First see if this is just a normal monitor message from the
 280          * other partition
 281          */
 282         if (hvlpevent_is_int(event)) {
 283                 remoteLp = event->xSourceLp;
 284                 if (!viopathStatus[remoteLp].isActive)
 285                         sendMonMsg(remoteLp);
 286                 return;
 287         }
 288
 289         /*
 290          * This path is for an acknowledgement; the other partition
 291          * died
 292          */
 293         remoteLp = event->xTargetLp;
 294         if ((event->xSourceInstanceId != viopathStatus[remoteLp].mSourceInst) ||
 295             (event->xTargetInstanceId != viopathStatus[remoteLp].mTargetInst)) {
 296                 printk(VIOPATH_KERN_WARN "ignoring ack....mismatched instances\n");
 297                 return;
 298         }
 299
 300         printk(VIOPATH_KERN_WARN "partition %d ended\n", remoteLp);
 301
 302         viopathStatus[remoteLp].isActive = 0;
 303
 304         /*
 305          * For each active handler, pass them a NULL
 306          * message to indicate that the other partition
 307          * died
 308          */
 309         for (i = 0; i < VIO_MAX_SUBTYPES; i++) {
 310                 if (vio_handler[i] != NULL)
 311                         (*vio_handler[i])(NULL);
 312         }
 313 }
 314
 315 int vio_setHandler(int subtype, vio_event_handler_t *beh)
 316 {
 317         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 318         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 319                 return -EINVAL;
 320         if (vio_handler[subtype] != NULL)
 321                 return -EBUSY;
 322         vio_handler[subtype] = beh;
 323         return 0;
 324 }
 325 EXPORT_SYMBOL(vio_setHandler);
 326
 327 int vio_clearHandler(int subtype)
 328 {
 329         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 330         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 331                 return -EINVAL;
 332         if (vio_handler[subtype] == NULL)
 333                 return -EAGAIN;
 334         vio_handler[subtype] = NULL;
 335         return 0;
 336 }
 337 EXPORT_SYMBOL(vio_clearHandler);
 338
 339 static void handleConfig(struct HvLpEvent *event)
 340 {
 341         if (!event)
 342                 return;
 343         if (hvlpevent_is_int(event)) {
 344                 printk(VIOPATH_KERN_WARN
 345                        "unexpected config request from partition %d",
 346                        event->xSourceLp);
 347
 348                 if (hvlpevent_need_ack(event)) {
 349                         event->xRc = HvLpEvent_Rc_InvalidSubtype;
 350                         HvCallEvent_ackLpEvent(event);
 351                 }
 352                 return;
 353         }
 354
 355         complete((struct completion *)event->xCorrelationToken);
 356 }
 357
 358 /*
 359  * Initialization of the hosting partition
 360  */
 361 void vio_set_hostlp(void)
 362 {
 363         /*
 364          * If this has already been set then we DON'T want to either change
 365          * it or re-register the proc file system
 366          */
 367         if (viopath_hostLp != HvLpIndexInvalid)
 368                 return;
 369
 370         /*
 371          * Figure out our hosting partition.  This isn't allowed to change
 372          * while we're active
 373          */
 374         viopath_ourLp = HvLpConfig_getLpIndex();
 375         viopath_hostLp = HvLpConfig_getHostingLpIndex(viopath_ourLp);
 376
 377         if (viopath_hostLp != HvLpIndexInvalid)
 378                 vio_setHandler(viomajorsubtype_config, handleConfig);
 379 }
 380 EXPORT_SYMBOL(vio_set_hostlp);
 381
 382 static void vio_handleEvent(struct HvLpEvent *event)
 383 {
 384         HvLpIndex remoteLp;
 385         int subtype = (event->xSubtype & VIOMAJOR_SUBTYPE_MASK)
 386                 >> VIOMAJOR_SUBTYPE_SHIFT;
 387
 388         if (hvlpevent_is_int(event)) {
 389                 remoteLp = event->xSourceLp;
 390                 /*
 391                  * The isActive is checked because if the hosting partition
 392                  * went down and came back up it would not be active but it
 393                  * would have different source and target instances, in which
 394                  * case we'd want to reset them.  This case really protects
 395                  * against an unauthorized active partition sending interrupts
 396                  * or acks to this linux partition.
 397                  */
 398                 if (viopathStatus[remoteLp].isActive
 399                     && (event->xSourceInstanceId !=
 400                         viopathStatus[remoteLp].mTargetInst)) {
 401                         printk(VIOPATH_KERN_WARN
 402                                "message from invalid partition. "
 403                                "int msg rcvd, source inst (%d) doesnt match (%d)\n",
 404                                viopathStatus[remoteLp].mTargetInst,
 405                                event->xSourceInstanceId);
 406                         return;
 407                 }
 408
 409                 if (viopathStatus[remoteLp].isActive
 410                     && (event->xTargetInstanceId !=
 411                         viopathStatus[remoteLp].mSourceInst)) {
 412                         printk(VIOPATH_KERN_WARN
 413                                "message from invalid partition. "
 414                                "int msg rcvd, target inst (%d) doesnt match (%d)\n",
 415                                viopathStatus[remoteLp].mSourceInst,
 416                                event->xTargetInstanceId);
 417                         return;
 418                 }
 419         } else {
 420                 remoteLp = event->xTargetLp;
 421                 if (event->xSourceInstanceId !=
 422                     viopathStatus[remoteLp].mSourceInst) {
 423                         printk(VIOPATH_KERN_WARN
 424                                "message from invalid partition. "
 425                                "ack msg rcvd, source inst (%d) doesnt match (%d)\n",
 426                                viopathStatus[remoteLp].mSourceInst,
 427                                event->xSourceInstanceId);
 428                         return;
 429                 }
 430
 431                 if (event->xTargetInstanceId !=
 432                     viopathStatus[remoteLp].mTargetInst) {
 433                         printk(VIOPATH_KERN_WARN
 434                                "message from invalid partition. "
 435                                "viopath: ack msg rcvd, target inst (%d) doesnt match (%d)\n",
 436                                viopathStatus[remoteLp].mTargetInst,
 437                                event->xTargetInstanceId);
 438                         return;
 439                 }
 440         }
 441
 442         if (vio_handler[subtype] == NULL) {
 443                 printk(VIOPATH_KERN_WARN
 444                        "unexpected virtual io event subtype %d from partition %d\n",
 445                        event->xSubtype, remoteLp);
 446                 /* No handler.  Ack if necessary */
 447                 if (hvlpevent_is_int(event) && hvlpevent_need_ack(event)) {
 448                         event->xRc = HvLpEvent_Rc_InvalidSubtype;
 449                         HvCallEvent_ackLpEvent(event);
 450                 }
 451                 return;
 452         }
 453
 454         /* This innocuous little line is where all the real work happens */
 455         (*vio_handler[subtype])(event);
 456 }
 457
 458 static void viopath_donealloc(void *parm, int number)
 459 {
 460         struct alloc_parms *parmsp = parm;
 461
 462         parmsp->number = number;
 463         if (parmsp->used_wait_atomic)
 464                 atomic_set(&parmsp->wait_atomic, 0);
 465         else
 466                 complete(&parmsp->done);
 467 }
 468
 469 static int allocateEvents(HvLpIndex remoteLp, int numEvents)
 470 {
 471         struct alloc_parms parms;
 472
 473         if (system_state != SYSTEM_RUNNING) {
 474                 parms.used_wait_atomic = 1;
 475                 atomic_set(&parms.wait_atomic, 1);
 476         } else {
 477                 parms.used_wait_atomic = 0;
 478                 init_completion(&parms.done);
 479         }
 480         mf_allocate_lp_events(remoteLp, HvLpEvent_Type_VirtualIo, 250,  /* It would be nice to put a real number here! */
 481                             numEvents, &viopath_donealloc, &parms);
 482         if (system_state != SYSTEM_RUNNING) {
 483                 while (atomic_read(&parms.wait_atomic))
 484                         mb();
 485         } else
 486                 wait_for_completion(&parms.done);
 487         return parms.number;
 488 }
 489
 490 int viopath_open(HvLpIndex remoteLp, int subtype, int numReq)
 491 {
 492         int i;
 493         unsigned long flags;
 494         int tempNumAllocated;
 495
 496         if ((remoteLp >= HVMAXARCHITECTEDLPS) || (remoteLp == HvLpIndexInvalid))
 497                 return -EINVAL;
 498
 499         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 500         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 501                 return -EINVAL;
 502
 503         spin_lock_irqsave(&statuslock, flags);
 504
 505         if (!event_buffer_initialised) {
 506                 for (i = 0; i < VIO_MAX_SUBTYPES; i++)
 507                         atomic_set(&event_buffer_available[i], 1);
 508                 event_buffer_initialised = 1;
 509         }
 510
 511         viopathStatus[remoteLp].users[subtype]++;
 512
 513         if (!viopathStatus[remoteLp].isOpen) {
 514                 viopathStatus[remoteLp].isOpen = 1;
 515                 HvCallEvent_openLpEventPath(remoteLp, HvLpEvent_Type_VirtualIo);
 516
 517                 /*
 518                  * Don't hold the spinlock during an operation that
 519                  * can sleep.
 520                  */
 521                 spin_unlock_irqrestore(&statuslock, flags);
 522                 tempNumAllocated = allocateEvents(remoteLp, 1);
 523                 spin_lock_irqsave(&statuslock, flags);
 524
 525                 viopathStatus[remoteLp].numberAllocated += tempNumAllocated;
 526
 527                 if (viopathStatus[remoteLp].numberAllocated == 0) {
 528                         HvCallEvent_closeLpEventPath(remoteLp,
 529                                         HvLpEvent_Type_VirtualIo);
 530
 531                         spin_unlock_irqrestore(&statuslock, flags);
 532                         return -ENOMEM;
 533                 }
 534
 535                 viopathStatus[remoteLp].mSourceInst =
 536                         HvCallEvent_getSourceLpInstanceId(remoteLp,
 537                                         HvLpEvent_Type_VirtualIo);
 538                 viopathStatus[remoteLp].mTargetInst =
 539                         HvCallEvent_getTargetLpInstanceId(remoteLp,
 540                                         HvLpEvent_Type_VirtualIo);
 541                 HvLpEvent_registerHandler(HvLpEvent_Type_VirtualIo,
 542                                           &vio_handleEvent);
 543                 sendMonMsg(remoteLp);
 544                 printk(VIOPATH_KERN_INFO "opening connection to partition %d, "
 545                                 "setting sinst %d, tinst %d\n",
 546                                 remoteLp, viopathStatus[remoteLp].mSourceInst,
 547                                 viopathStatus[remoteLp].mTargetInst);
 548         }
 549
 550         spin_unlock_irqrestore(&statuslock, flags);
 551         tempNumAllocated = allocateEvents(remoteLp, numReq);
 552         spin_lock_irqsave(&statuslock, flags);
 553         viopathStatus[remoteLp].numberAllocated += tempNumAllocated;
 554         spin_unlock_irqrestore(&statuslock, flags);
 555
 556         return 0;
 557 }
 558 EXPORT_SYMBOL(viopath_open);
 559
 560 int viopath_close(HvLpIndex remoteLp, int subtype, int numReq)
 561 {
 562         unsigned long flags;
 563         int i;
 564         int numOpen;
 565         struct alloc_parms parms;
 566
 567         if ((remoteLp >= HVMAXARCHITECTEDLPS) || (remoteLp == HvLpIndexInvalid))
 568                 return -EINVAL;
 569
 570         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 571         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 572                 return -EINVAL;
 573
 574         spin_lock_irqsave(&statuslock, flags);
 575         /*
 576          * If the viopath_close somehow gets called before a
 577          * viopath_open it could decrement to -1 which is a non
 578          * recoverable state so we'll prevent this from
 579          * happening.
 580          */
 581         if (viopathStatus[remoteLp].users[subtype] > 0)
 582                 viopathStatus[remoteLp].users[subtype]--;
 583
 584         spin_unlock_irqrestore(&statuslock, flags);
 585
 586         parms.used_wait_atomic = 0;
 587         init_completion(&parms.done);
 588         mf_deallocate_lp_events(remoteLp, HvLpEvent_Type_VirtualIo,
 589                               numReq, &viopath_donealloc, &parms);
 590         wait_for_completion(&parms.done);
 591
 592         spin_lock_irqsave(&statuslock, flags);
 593         for (i = 0, numOpen = 0; i < VIO_MAX_SUBTYPES; i++)
 594                 numOpen += viopathStatus[remoteLp].users[i];
 595
 596         if ((viopathStatus[remoteLp].isOpen) && (numOpen == 0)) {
 597                 printk(VIOPATH_KERN_INFO "closing connection to partition %d\n",
 598                                 remoteLp);
 599
 600                 HvCallEvent_closeLpEventPath(remoteLp,
 601                                              HvLpEvent_Type_VirtualIo);
 602                 viopathStatus[remoteLp].isOpen = 0;
 603                 viopathStatus[remoteLp].isActive = 0;
 604
 605                 for (i = 0; i < VIO_MAX_SUBTYPES; i++)
 606                         atomic_set(&event_buffer_available[i], 0);
 607                 event_buffer_initialised = 0;
 608         }
 609         spin_unlock_irqrestore(&statuslock, flags);
 610         return 0;
 611 }
 612 EXPORT_SYMBOL(viopath_close);
 613
 614 void *vio_get_event_buffer(int subtype)
 615 {
 616         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 617         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
 618                 return NULL;
 619
 620         if (atomic_dec_if_positive(&event_buffer_available[subtype]) == 0)
 621                 return &event_buffer[subtype * 256];
 622         else
 623                 return NULL;
 624 }
 625 EXPORT_SYMBOL(vio_get_event_buffer);
 626
 627 void vio_free_event_buffer(int subtype, void *buffer)
 628 {
 629         subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
 630         if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES)) {
 631                 printk(VIOPATH_KERN_WARN
 632                        "unexpected subtype %d freeing event buffer\n", subtype);
 633                 return;
 634         }
 635
 636         if (atomic_read(&event_buffer_available[subtype]) != 0) {
 637                 printk(VIOPATH_KERN_WARN
 638                        "freeing unallocated event buffer, subtype %d\n",
 639                        subtype);
 640                 return;
 641         }
 642
 643         if (buffer != &event_buffer[subtype * 256]) {
 644                 printk(VIOPATH_KERN_WARN
 645                        "freeing invalid event buffer, subtype %d\n", subtype);
 646         }
 647
 648         atomic_set(&event_buffer_available[subtype], 1);
 649 }
 650 EXPORT_SYMBOL(vio_free_event_buffer);
 651
 652 static const struct vio_error_entry vio_no_error =
 653     { 0, 0, "Non-VIO Error" };
 654 static const struct vio_error_entry vio_unknown_error =
 655     { 0, EIO, "Unknown Error" };
 656
 657 static const struct vio_error_entry vio_default_errors[] = {
 658         {0x0001, EIO, "No Connection"},
 659         {0x0002, EIO, "No Receiver"},
 660         {0x0003, EIO, "No Buffer Available"},
 661         {0x0004, EBADRQC, "Invalid Message Type"},
 662         {0x0000, 0, NULL},
 663 };
 664
 665 const struct vio_error_entry *vio_lookup_rc(
 666                 const struct vio_error_entry *local_table, u16 rc)
 667 {
 668         const struct vio_error_entry *cur;
 669
 670         if (!rc)
 671                 return &vio_no_error;
 672         if (local_table)
 673                 for (cur = local_table; cur->rc; ++cur)
 674                         if (cur->rc == rc)
 675                                 return cur;
 676         for (cur = vio_default_errors; cur->rc; ++cur)
 677                 if (cur->rc == rc)
 678                         return cur;
 679         return &vio_unknown_error;
 680 }
 681 EXPORT_SYMBOL(vio_lookup_rc);