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