arch/ia64/sn/kernel/sn2/sn_hwperf.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (C) 2004-2005 Silicon Graphics, Inc. All rights reserved.
   7  *
   8  * SGI Altix topology and hardware performance monitoring API.
   9  * Mark Goodwin <markgw@sgi.com>.
  10  *
  11  * Creates /proc/sgi_sn/sn_topology (read-only) to export
  12  * info about Altix nodes, routers, CPUs and NumaLink
  13  * interconnection/topology.
  14  *
  15  * Also creates a dynamic misc device named "sn_hwperf"
  16  * that supports an ioctl interface to call down into SAL
  17  * to discover hw objects, topology and to read/write
  18  * memory mapped registers, e.g. for performance monitoring.
  19  * The "sn_hwperf" device is registered only after the procfs
  20  * file is first opened, i.e. only if/when it's needed.
  21  *
  22  * This API is used by SGI Performance Co-Pilot and other
  23  * tools, see http://oss.sgi.com/projects/pcp
  24  */
  25
  26 #include <linux/fs.h>
  27 #include <linux/slab.h>
  28 #include <linux/vmalloc.h>
  29 #include <linux/seq_file.h>
  30 #include <linux/miscdevice.h>
  31 #include <linux/cpumask.h>
  32 #include <linux/smp_lock.h>
  33 #include <linux/nodemask.h>
  34 #include <asm/processor.h>
  35 #include <asm/topology.h>
  36 #include <asm/smp.h>
  37 #include <asm/semaphore.h>
  38 #include <asm/segment.h>
  39 #include <asm/uaccess.h>
  40 #include <asm/sal.h>
  41 #include <asm/sn/io.h>
  42 #include <asm/sn/sn_sal.h>
  43 #include <asm/sn/module.h>
  44 #include <asm/sn/geo.h>
  45 #include <asm/sn/sn2/sn_hwperf.h>
  46
  47 static void *sn_hwperf_salheap = NULL;
  48 static int sn_hwperf_obj_cnt = 0;
  49 static nasid_t sn_hwperf_master_nasid = INVALID_NASID;
  50 static int sn_hwperf_init(void);
  51 static DECLARE_MUTEX(sn_hwperf_init_mutex);
  52
  53 static int sn_hwperf_enum_objects(int *nobj, struct sn_hwperf_object_info **ret)
  54 {
  55         int e;
  56         u64 sz;
  57         struct sn_hwperf_object_info *objbuf = NULL;
  58
  59         if ((e = sn_hwperf_init()) < 0) {
  60                 printk("sn_hwperf_init failed: err %d\n", e);
  61                 goto out;
  62         }
  63
  64         sz = sn_hwperf_obj_cnt * sizeof(struct sn_hwperf_object_info);
  65         if ((objbuf = (struct sn_hwperf_object_info *) vmalloc(sz)) == NULL) {
  66                 printk("sn_hwperf_enum_objects: vmalloc(%d) failed\n", (int)sz);
  67                 e = -ENOMEM;
  68                 goto out;
  69         }
  70
  71         e = ia64_sn_hwperf_op(sn_hwperf_master_nasid, SN_HWPERF_ENUM_OBJECTS,
  72                 0, sz, (u64) objbuf, 0, 0, NULL);
  73         if (e != SN_HWPERF_OP_OK) {
  74                 e = -EINVAL;
  75                 vfree(objbuf);
  76         }
  77
  78 out:
  79         *nobj = sn_hwperf_obj_cnt;
  80         *ret = objbuf;
  81         return e;
  82 }
  83
  84 static int sn_hwperf_geoid_to_cnode(char *location)
  85 {
  86         int cnode;
  87         geoid_t geoid;
  88         moduleid_t module_id;
  89         char type;
  90         int rack, slot, slab;
  91         int this_rack, this_slot, this_slab;
  92
  93         if (sscanf(location, "%03d%c%02d#%d", &rack, &type, &slot, &slab) != 4)
  94                 return -1;
  95
  96         for (cnode = 0; cnode < numionodes; cnode++) {
  97                 geoid = cnodeid_get_geoid(cnode);
  98                 module_id = geo_module(geoid);
  99                 this_rack = MODULE_GET_RACK(module_id);
 100                 this_slot = MODULE_GET_BPOS(module_id);
 101                 this_slab = geo_slab(geoid);
 102                 if (rack == this_rack && slot == this_slot && slab == this_slab)
 103                         break;
 104         }
 105
 106         return cnode < numionodes ? cnode : -1;
 107 }
 108
 109 static int sn_hwperf_obj_to_cnode(struct sn_hwperf_object_info * obj)
 110 {
 111         if (!obj->sn_hwp_this_part)
 112                 return -1;
 113         return sn_hwperf_geoid_to_cnode(obj->location);
 114 }
 115
 116 static int sn_hwperf_generic_ordinal(struct sn_hwperf_object_info *obj,
 117                                 struct sn_hwperf_object_info *objs)
 118 {
 119         int ordinal;
 120         struct sn_hwperf_object_info *p;
 121
 122         for (ordinal=0, p=objs; p != obj; p++) {
 123                 if (SN_HWPERF_FOREIGN(p))
 124                         continue;
 125                 if (SN_HWPERF_SAME_OBJTYPE(p, obj))
 126                         ordinal++;
 127         }
 128
 129         return ordinal;
 130 }
 131
 132 static const char *slabname_node =      "node"; /* SHub asic */
 133 static const char *slabname_ionode =    "ionode"; /* TIO asic */
 134 static const char *slabname_router =    "router"; /* NL3R or NL4R */
 135 static const char *slabname_other =     "other"; /* unknown asic */
 136
 137 static const char *sn_hwperf_get_slabname(struct sn_hwperf_object_info *obj,
 138                         struct sn_hwperf_object_info *objs, int *ordinal)
 139 {
 140         int isnode;
 141         const char *slabname = slabname_other;
 142
 143         if ((isnode = SN_HWPERF_IS_NODE(obj)) || SN_HWPERF_IS_IONODE(obj)) {
 144                 slabname = isnode ? slabname_node : slabname_ionode;
 145                 *ordinal = sn_hwperf_obj_to_cnode(obj);
 146         }
 147         else {
 148                 *ordinal = sn_hwperf_generic_ordinal(obj, objs);
 149                 if (SN_HWPERF_IS_ROUTER(obj))
 150                         slabname = slabname_router;
 151         }
 152
 153         return slabname;
 154 }
 155
 156 static int sn_topology_show(struct seq_file *s, void *d)
 157 {
 158         int sz;
 159         int pt;
 160         int e;
 161         int i;
 162         int j;
 163         const char *slabname;
 164         int ordinal;
 165         cpumask_t cpumask;
 166         char slice;
 167         struct cpuinfo_ia64 *c;
 168         struct sn_hwperf_port_info *ptdata;
 169         struct sn_hwperf_object_info *p;
 170         struct sn_hwperf_object_info *obj = d;  /* this object */
 171         struct sn_hwperf_object_info *objs = s->private; /* all objects */
 172
 173         if (obj == objs) {
 174                 seq_printf(s, "# sn_topology version 1\n");
 175                 seq_printf(s, "# objtype ordinal location partition"
 176                         " [attribute value [, ...]]\n");
 177         }
 178
 179         if (SN_HWPERF_FOREIGN(obj)) {
 180                 /* private in another partition: not interesting */
 181                 return 0;
 182         }
 183
 184         for (i = 0; obj->name[i]; i++) {
 185                 if (obj->name[i] == ' ')
 186                         obj->name[i] = '_';
 187         }
 188
 189         slabname = sn_hwperf_get_slabname(obj, objs, &ordinal);
 190         seq_printf(s, "%s %d %s %s asic %s", slabname, ordinal, obj->location,
 191                 obj->sn_hwp_this_part ? "local" : "shared", obj->name);
 192
 193         if (!SN_HWPERF_IS_NODE(obj) && !SN_HWPERF_IS_IONODE(obj))
 194                 seq_putc(s, '\n');
 195         else {
 196                 seq_printf(s, ", nasid 0x%x", cnodeid_to_nasid(ordinal));
 197                 for (i=0; i < numionodes; i++) {
 198                         seq_printf(s, i ? ":%d" : ", dist %d",
 199                                 node_distance(ordinal, i));
 200                 }
 201                 seq_putc(s, '\n');
 202
 203                 /*
 204                  * CPUs on this node, if any
 205                  */
 206                 cpumask = node_to_cpumask(ordinal);
 207                 for_each_online_cpu(i) {
 208                         if (cpu_isset(i, cpumask)) {
 209                                 slice = 'a' + cpuid_to_slice(i);
 210                                 c = cpu_data(i);
 211                                 seq_printf(s, "cpu %d %s%c local"
 212                                         " freq %luMHz, arch ia64",
 213                                         i, obj->location, slice,
 214                                         c->proc_freq / 1000000);
 215                                 for_each_online_cpu(j) {
 216                                         seq_printf(s, j ? ":%d" : ", dist %d",
 217                                                 node_distance(
 218                                                     cpuid_to_cnodeid(i),
 219                                                     cpuid_to_cnodeid(j)));
 220                                 }
 221                                 seq_putc(s, '\n');
 222                         }
 223                 }
 224         }
 225
 226         if (obj->ports) {
 227                 /*
 228                  * numalink ports
 229                  */
 230                 sz = obj->ports * sizeof(struct sn_hwperf_port_info);
 231                 if ((ptdata = vmalloc(sz)) == NULL)
 232                         return -ENOMEM;
 233                 e = ia64_sn_hwperf_op(sn_hwperf_master_nasid,
 234                                       SN_HWPERF_ENUM_PORTS, obj->id, sz,
 235                                       (u64) ptdata, 0, 0, NULL);
 236                 if (e != SN_HWPERF_OP_OK)
 237                         return -EINVAL;
 238                 for (ordinal=0, p=objs; p != obj; p++) {
 239                         if (!SN_HWPERF_FOREIGN(p))
 240                                 ordinal += p->ports;
 241                 }
 242                 for (pt = 0; pt < obj->ports; pt++) {
 243                         for (p = objs, i = 0; i < sn_hwperf_obj_cnt; i++, p++) {
 244                                 if (ptdata[pt].conn_id == p->id) {
 245                                         break;
 246                                 }
 247                         }
 248                         seq_printf(s, "numalink %d %s-%d",
 249                             ordinal+pt, obj->location, ptdata[pt].port);
 250
 251                         if (i >= sn_hwperf_obj_cnt) {
 252                                 /* no connection */
 253                                 seq_puts(s, " local endpoint disconnected"
 254                                             ", protocol unknown\n");
 255                                 continue;
 256                         }
 257
 258                         if (obj->sn_hwp_this_part && p->sn_hwp_this_part)
 259                                 /* both ends local to this partition */
 260                                 seq_puts(s, " local");
 261                         else if (!obj->sn_hwp_this_part && !p->sn_hwp_this_part)
 262                                 /* both ends of the link in foreign partiton */
 263                                 seq_puts(s, " foreign");
 264                         else
 265                                 /* link straddles a partition */
 266                                 seq_puts(s, " shared");
 267
 268                         /*
 269                          * Unlikely, but strictly should query the LLP config
 270                          * registers because an NL4R can be configured to run
 271                          * NL3 protocol, even when not talking to an NL3 router.
 272                          * Ditto for node-node.
 273                          */
 274                         seq_printf(s, " endpoint %s-%d, protocol %s\n",
 275                                 p->location, ptdata[pt].conn_port,
 276                                 (SN_HWPERF_IS_NL3ROUTER(obj) ||
 277                                 SN_HWPERF_IS_NL3ROUTER(p)) ?  "LLP3" : "LLP4");
 278                 }
 279                 vfree(ptdata);
 280         }
 281
 282         return 0;
 283 }
 284
 285 static void *sn_topology_start(struct seq_file *s, loff_t * pos)
 286 {
 287         struct sn_hwperf_object_info *objs = s->private;
 288
 289         if (*pos < sn_hwperf_obj_cnt)
 290                 return (void *)(objs + *pos);
 291
 292         return NULL;
 293 }
 294
 295 static void *sn_topology_next(struct seq_file *s, void *v, loff_t * pos)
 296 {
 297         ++*pos;
 298         return sn_topology_start(s, pos);
 299 }
 300
 301 static void sn_topology_stop(struct seq_file *m, void *v)
 302 {
 303         return;
 304 }
 305
 306 /*
 307  * /proc/sgi_sn/sn_topology, read-only using seq_file
 308  */
 309 static struct seq_operations sn_topology_seq_ops = {
 310         .start = sn_topology_start,
 311         .next = sn_topology_next,
 312         .stop = sn_topology_stop,
 313         .show = sn_topology_show
 314 };
 315
 316 struct sn_hwperf_op_info {
 317         u64 op;
 318         struct sn_hwperf_ioctl_args *a;
 319         void *p;
 320         int *v0;
 321         int ret;
 322 };
 323
 324 static void sn_hwperf_call_sal(void *info)
 325 {
 326         struct sn_hwperf_op_info *op_info = info;
 327         int r;
 328
 329         r = ia64_sn_hwperf_op(sn_hwperf_master_nasid, op_info->op,
 330                       op_info->a->arg, op_info->a->sz,
 331                       (u64) op_info->p, 0, 0, op_info->v0);
 332         op_info->ret = r;
 333 }
 334
 335 static int sn_hwperf_op_cpu(struct sn_hwperf_op_info *op_info)
 336 {
 337         u32 cpu;
 338         u32 use_ipi;
 339         int r = 0;
 340         cpumask_t save_allowed;
 341
 342         cpu = (op_info->a->arg & SN_HWPERF_ARG_CPU_MASK) >> 32;
 343         use_ipi = op_info->a->arg & SN_HWPERF_ARG_USE_IPI_MASK;
 344         op_info->a->arg &= SN_HWPERF_ARG_OBJID_MASK;
 345
 346         if (cpu != SN_HWPERF_ARG_ANY_CPU) {
 347                 if (cpu >= num_online_cpus() || !cpu_online(cpu)) {
 348                         r = -EINVAL;
 349                         goto out;
 350                 }
 351         }
 352
 353         if (cpu == SN_HWPERF_ARG_ANY_CPU || cpu == get_cpu()) {
 354                 /* don't care, or already on correct cpu */
 355                 sn_hwperf_call_sal(op_info);
 356         }
 357         else {
 358                 if (use_ipi) {
 359                         /* use an interprocessor interrupt to call SAL */
 360                         smp_call_function_single(cpu, sn_hwperf_call_sal,
 361                                 op_info, 1, 1);
 362                 }
 363                 else {
 364                         /* migrate the task before calling SAL */
 365                         save_allowed = current->cpus_allowed;
 366                         set_cpus_allowed(current, cpumask_of_cpu(cpu));
 367                         sn_hwperf_call_sal(op_info);
 368                         set_cpus_allowed(current, save_allowed);
 369                 }
 370         }
 371         r = op_info->ret;
 372
 373 out:
 374         return r;
 375 }
 376
 377 /* map SAL hwperf error code to system error code */
 378 static int sn_hwperf_map_err(int hwperf_err)
 379 {
 380         int e;
 381
 382         switch(hwperf_err) {
 383         case SN_HWPERF_OP_OK:
 384                 e = 0;
 385                 break;
 386
 387         case SN_HWPERF_OP_NOMEM:
 388                 e = -ENOMEM;
 389                 break;
 390
 391         case SN_HWPERF_OP_NO_PERM:
 392                 e = -EPERM;
 393                 break;
 394
 395         case SN_HWPERF_OP_IO_ERROR:
 396                 e = -EIO;
 397                 break;
 398
 399         case SN_HWPERF_OP_BUSY:
 400         case SN_HWPERF_OP_RECONFIGURE:
 401                 e = -EAGAIN;
 402                 break;
 403
 404         case SN_HWPERF_OP_INVAL:
 405         default:
 406                 e = -EINVAL;
 407                 break;
 408         }
 409
 410         return e;
 411 }
 412
 413 /*
 414  * ioctl for "sn_hwperf" misc device
 415  */
 416 static int
 417 sn_hwperf_ioctl(struct inode *in, struct file *fp, u32 op, u64 arg)
 418 {
 419         struct sn_hwperf_ioctl_args a;
 420         struct cpuinfo_ia64 *cdata;
 421         struct sn_hwperf_object_info *objs;
 422         struct sn_hwperf_object_info *cpuobj;
 423         struct sn_hwperf_op_info op_info;
 424         void *p = NULL;
 425         int nobj;
 426         char slice;
 427         int node;
 428         int r;
 429         int v0;
 430         int i;
 431         int j;
 432
 433         unlock_kernel();
 434
 435         /* only user requests are allowed here */
 436         if ((op & SN_HWPERF_OP_MASK) < 10) {
 437                 r = -EINVAL;
 438                 goto error;
 439         }
 440         r = copy_from_user(&a, (const void __user *)arg,
 441                 sizeof(struct sn_hwperf_ioctl_args));
 442         if (r != 0) {
 443                 r = -EFAULT;
 444                 goto error;
 445         }
 446
 447         /*
 448          * Allocate memory to hold a kernel copy of the user buffer. The
 449          * buffer contents are either copied in or out (or both) of user
 450          * space depending on the flags encoded in the requested operation.
 451          */
 452         if (a.ptr) {
 453                 p = vmalloc(a.sz);
 454                 if (!p) {
 455                         r = -ENOMEM;
 456                         goto error;
 457                 }
 458         }
 459
 460         if (op & SN_HWPERF_OP_MEM_COPYIN) {
 461                 r = copy_from_user(p, (const void __user *)a.ptr, a.sz);
 462                 if (r != 0) {
 463                         r = -EFAULT;
 464                         goto error;
 465                 }
 466         }
 467
 468         switch (op) {
 469         case SN_HWPERF_GET_CPU_INFO:
 470                 if (a.sz == sizeof(u64)) {
 471                         /* special case to get size needed */
 472                         *(u64 *) p = (u64) num_online_cpus() *
 473                                 sizeof(struct sn_hwperf_object_info);
 474                 } else
 475                 if (a.sz < num_online_cpus() * sizeof(struct sn_hwperf_object_info)) {
 476                         r = -ENOMEM;
 477                         goto error;
 478                 } else
 479                 if ((r = sn_hwperf_enum_objects(&nobj, &objs)) == 0) {
 480                         memset(p, 0, a.sz);
 481                         for (i = 0; i < nobj; i++) {
 482                                 node = sn_hwperf_obj_to_cnode(objs + i);
 483                                 for_each_online_cpu(j) {
 484                                         if (node != cpu_to_node(j))
 485                                                 continue;
 486                                         cpuobj = (struct sn_hwperf_object_info *) p + j;
 487                                         slice = 'a' + cpuid_to_slice(j);
 488                                         cdata = cpu_data(j);
 489                                         cpuobj->id = j;
 490                                         snprintf(cpuobj->name,
 491                                                  sizeof(cpuobj->name),
 492                                                  "CPU %luMHz %s",
 493                                                  cdata->proc_freq / 1000000,
 494                                                  cdata->vendor);
 495                                         snprintf(cpuobj->location,
 496                                                  sizeof(cpuobj->location),
 497                                                  "%s%c", objs[i].location,
 498                                                  slice);
 499                                 }
 500                         }
 501
 502                         vfree(objs);
 503                 }
 504                 break;
 505
 506         case SN_HWPERF_GET_NODE_NASID:
 507                 if (a.sz != sizeof(u64) ||
 508                    (node = a.arg) < 0 || node >= numionodes) {
 509                         r = -EINVAL;
 510                         goto error;
 511                 }
 512                 *(u64 *)p = (u64)cnodeid_to_nasid(node);
 513                 break;
 514
 515         case SN_HWPERF_GET_OBJ_NODE:
 516                 if (a.sz != sizeof(u64) || a.arg < 0) {
 517                         r = -EINVAL;
 518                         goto error;
 519                 }
 520                 if ((r = sn_hwperf_enum_objects(&nobj, &objs)) == 0) {
 521                         if (a.arg >= nobj) {
 522                                 r = -EINVAL;
 523                                 vfree(objs);
 524                                 goto error;
 525                         }
 526                         if (objs[(i = a.arg)].id != a.arg) {
 527                                 for (i = 0; i < nobj; i++) {
 528                                         if (objs[i].id == a.arg)
 529                                                 break;
 530                                 }
 531                         }
 532                         if (i == nobj) {
 533                                 r = -EINVAL;
 534                                 vfree(objs);
 535                                 goto error;
 536                         }
 537                         *(u64 *)p = (u64)sn_hwperf_obj_to_cnode(objs + i);
 538                         vfree(objs);
 539                 }
 540                 break;
 541
 542         case SN_HWPERF_GET_MMRS:
 543         case SN_HWPERF_SET_MMRS:
 544         case SN_HWPERF_OBJECT_DISTANCE:
 545                 op_info.p = p;
 546                 op_info.a = &a;
 547                 op_info.v0 = &v0;
 548                 op_info.op = op;
 549                 r = sn_hwperf_op_cpu(&op_info);
 550                 if (r) {
 551                         r = sn_hwperf_map_err(r);
 552                         goto error;
 553                 }
 554                 break;
 555
 556         default:
 557                 /* all other ops are a direct SAL call */
 558                 r = ia64_sn_hwperf_op(sn_hwperf_master_nasid, op,
 559                               a.arg, a.sz, (u64) p, 0, 0, &v0);
 560                 if (r) {
 561                         r = sn_hwperf_map_err(r);
 562                         goto error;
 563                 }
 564                 a.v0 = v0;
 565                 break;
 566         }
 567
 568         if (op & SN_HWPERF_OP_MEM_COPYOUT) {
 569                 r = copy_to_user((void __user *)a.ptr, p, a.sz);
 570                 if (r != 0) {
 571                         r = -EFAULT;
 572                         goto error;
 573                 }
 574         }
 575
 576 error:
 577         vfree(p);
 578
 579         lock_kernel();
 580         return r;
 581 }
 582
 583 static struct file_operations sn_hwperf_fops = {
 584         .ioctl = sn_hwperf_ioctl,
 585 };
 586
 587 static struct miscdevice sn_hwperf_dev = {
 588         MISC_DYNAMIC_MINOR,
 589         "sn_hwperf",
 590         &sn_hwperf_fops
 591 };
 592
 593 static int sn_hwperf_init(void)
 594 {
 595         u64 v;
 596         int salr;
 597         int e = 0;
 598
 599         /* single threaded, once-only initialization */
 600         down(&sn_hwperf_init_mutex);
 601         if (sn_hwperf_salheap) {
 602                 up(&sn_hwperf_init_mutex);
 603                 return e;
 604         }
 605
 606         /*
 607          * The PROM code needs a fixed reference node. For convenience the
 608          * same node as the console I/O is used.
 609          */
 610         sn_hwperf_master_nasid = (nasid_t) ia64_sn_get_console_nasid();
 611
 612         /*
 613          * Request the needed size and install the PROM scratch area.
 614          * The PROM keeps various tracking bits in this memory area.
 615          */
 616         salr = ia64_sn_hwperf_op(sn_hwperf_master_nasid,
 617                                  (u64) SN_HWPERF_GET_HEAPSIZE, 0,
 618                                  (u64) sizeof(u64), (u64) &v, 0, 0, NULL);
 619         if (salr != SN_HWPERF_OP_OK) {
 620                 e = -EINVAL;
 621                 goto out;
 622         }
 623
 624         if ((sn_hwperf_salheap = vmalloc(v)) == NULL) {
 625                 e = -ENOMEM;
 626                 goto out;
 627         }
 628         salr = ia64_sn_hwperf_op(sn_hwperf_master_nasid,
 629                                  SN_HWPERF_INSTALL_HEAP, 0, v,
 630                                  (u64) sn_hwperf_salheap, 0, 0, NULL);
 631         if (salr != SN_HWPERF_OP_OK) {
 632                 e = -EINVAL;
 633                 goto out;
 634         }
 635
 636         salr = ia64_sn_hwperf_op(sn_hwperf_master_nasid,
 637                                  SN_HWPERF_OBJECT_COUNT, 0,
 638                                  sizeof(u64), (u64) &v, 0, 0, NULL);
 639         if (salr != SN_HWPERF_OP_OK) {
 640                 e = -EINVAL;
 641                 goto out;
 642         }
 643         sn_hwperf_obj_cnt = (int)v;
 644
 645 out:
 646         if (e < 0 && sn_hwperf_salheap) {
 647                 vfree(sn_hwperf_salheap);
 648                 sn_hwperf_salheap = NULL;
 649                 sn_hwperf_obj_cnt = 0;
 650         }
 651
 652         if (!e) {
 653                 /*
 654                  * Register a dynamic misc device for ioctl. Platforms
 655                  * supporting hotplug will create /dev/sn_hwperf, else
 656                  * user can to look up the minor number in /proc/misc.
 657                  */
 658                 if ((e = misc_register(&sn_hwperf_dev)) != 0) {
 659                         printk(KERN_ERR "sn_hwperf_init: misc register "
 660                                "for \"sn_hwperf\" failed, err %d\n", e);
 661                 }
 662         }
 663
 664         up(&sn_hwperf_init_mutex);
 665         return e;
 666 }
 667
 668 int sn_topology_open(struct inode *inode, struct file *file)
 669 {
 670         int e;
 671         struct seq_file *seq;
 672         struct sn_hwperf_object_info *objbuf;
 673         int nobj;
 674
 675         if ((e = sn_hwperf_enum_objects(&nobj, &objbuf)) == 0) {
 676                 e = seq_open(file, &sn_topology_seq_ops);
 677                 seq = file->private_data;
 678                 seq->private = objbuf;
 679         }
 680
 681         return e;
 682 }
 683
 684 int sn_topology_release(struct inode *inode, struct file *file)
 685 {
 686         struct seq_file *seq = file->private_data;
 687
 688         vfree(seq->private);
 689         return seq_release(inode, file);
 690 }