sys/dev/acpica/acpi_hpet.c

   1 /*-
   2  * Copyright (c) 2005 Poul-Henning Kamp
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  * $FreeBSD: src/sys/dev/acpica/acpi_hpet.c,v 1.12.2.1.2.1 2008/11/25 02:59:29 kensmith Exp $
  27  */
  28
  29 #include "opt_acpi.h"
  30
  31 #include <sys/param.h>
  32 #include <sys/bus.h>
  33 #include <sys/kernel.h>
  34 #include <sys/module.h>
  35 #include <sys/systimer.h>
  36 #include <sys/rman.h>
  37
  38 #if !defined(KLD_MODULE)
  39 #include <machine/pmap.h>
  40 #endif
  41
  42 #include "acpi.h"
  43 #include "accommon.h"
  44 #include "acpivar.h"
  45 #include "acpi_hpet.h"
  46
  47 #if !defined(KLD_MODULE)
  48 #include <platform/pc64/acpica/acpi_sdt_var.h>
  49 #endif
  50
  51 /* Hooks for the ACPICA debugging infrastructure */
  52 #define _COMPONENT      ACPI_TIMER
  53 ACPI_MODULE_NAME("HPET")
  54
  55 static bus_space_handle_t       acpi_hpet_bsh;
  56 static bus_space_tag_t          acpi_hpet_bst;
  57 static u_long                   acpi_hpet_res_start;
  58
  59 struct acpi_hpet_softc {
  60         device_t                dev;
  61         struct resource         *mem_res;
  62         ACPI_HANDLE             handle;
  63 };
  64
  65 #define DEV_HPET(x)     (acpi_get_magic(x) == (uintptr_t)&acpi_hpet_devclass)
  66
  67 static sysclock_t       acpi_hpet_get_timecount(void);
  68 static void             acpi_hpet_construct(struct cputimer *, sysclock_t);
  69
  70 static int              acpi_hpet_identify(driver_t *, device_t);
  71 static int              acpi_hpet_probe(device_t);
  72 static int              acpi_hpet_attach(device_t);
  73 static int              acpi_hpet_resume(device_t);
  74 static int              acpi_hpet_suspend(device_t);
  75
  76 static void             acpi_hpet_test(struct acpi_hpet_softc *sc);
  77 static u_int            acpi_hpet_read(void);
  78 static void             acpi_hpet_enable(struct acpi_hpet_softc *);
  79 static void             acpi_hpet_disable(struct acpi_hpet_softc *);
  80
  81 static char *hpet_ids[] = { "PNP0103", NULL };
  82
  83 static struct cputimer acpi_hpet_timer = {
  84         .next           = SLIST_ENTRY_INITIALIZER,
  85         .name           = "HPET",
  86         .pri            = CPUTIMER_PRI_HPET,
  87         .type           = CPUTIMER_HPET,
  88         .count          = acpi_hpet_get_timecount,
  89         .fromhz         = cputimer_default_fromhz,
  90         .fromus         = cputimer_default_fromus,
  91         .construct      = acpi_hpet_construct,
  92         .destruct       = cputimer_default_destruct,
  93         .freq           = 0     /* determined later */
  94 };
  95
  96 static device_method_t acpi_hpet_methods[] = {
  97         DEVMETHOD(device_identify,      acpi_hpet_identify),
  98         DEVMETHOD(device_probe,         acpi_hpet_probe),
  99         DEVMETHOD(device_attach,        acpi_hpet_attach),
 100         DEVMETHOD(device_suspend,       acpi_hpet_suspend),
 101         DEVMETHOD(device_resume,        acpi_hpet_resume),
 102         DEVMETHOD_END
 103 };
 104
 105 static driver_t acpi_hpet_driver = {
 106         "acpi_hpet",
 107         acpi_hpet_methods,
 108         sizeof(struct acpi_hpet_softc),
 109         .gpri = KOBJ_GPRI_ACPI+2
 110 };
 111
 112 static devclass_t acpi_hpet_devclass;
 113 DRIVER_MODULE(acpi_hpet, acpi, acpi_hpet_driver, acpi_hpet_devclass, NULL, NULL);
 114 MODULE_DEPEND(acpi_hpet, acpi, 1, 1, 1);
 115
 116 static u_int
 117 acpi_hpet_read(void)
 118 {
 119         return bus_space_read_4(acpi_hpet_bst, acpi_hpet_bsh,
 120                                 HPET_MAIN_COUNTER);
 121 }
 122
 123 #if !defined(KLD_MODULE)
 124 extern int i8254_cputimer_disable;
 125
 126 static vm_offset_t ptr = 0;
 127
 128 static int acpi_hpet_for_calibration = 1;
 129 TUNABLE_INT("hw.calibrate_timers_with_hpet", &acpi_hpet_for_calibration);
 130
 131 static sysclock_t
 132 acpi_hpet_early_get_timecount(void)
 133 {
 134         return readl(ptr + HPET_MAIN_COUNTER) + acpi_hpet_timer.base;
 135 }
 136
 137 static void
 138 acpi_hpet_early_construct(struct cputimer *timer, sysclock_t oldclock)
 139 {
 140         uint32_t val;
 141
 142         val = readl(ptr + HPET_CONFIG);
 143         writel(ptr + HPET_CONFIG, val | HPET_CNF_ENABLE);
 144
 145         timer->base = 0;
 146         timer->base = oldclock - acpi_hpet_early_get_timecount();
 147 }
 148
 149 static void
 150 acpi_hpet_early_destruct(struct cputimer *timer)
 151 {
 152         uint32_t val;
 153
 154         val = readl(ptr + HPET_CONFIG);
 155         writel(ptr + HPET_CONFIG, val & ~HPET_CNF_ENABLE);
 156 }
 157
 158 static int
 159 acpi_hpet_early_init(void)
 160 {
 161         uintmax_t freq;
 162         uint64_t old_tsc, new_tsc;
 163         uint32_t val, val2;
 164
 165         val = readl(ptr + HPET_CONFIG);
 166         writel(ptr + HPET_CONFIG, val | HPET_CNF_ENABLE);
 167
 168         /* Read basic statistics about the timer. */
 169         val = readl(ptr + HPET_PERIOD);
 170         if (val == 0) {
 171                 kprintf("acpi_hpet: invalid period\n");
 172                 val = readl(ptr + HPET_CONFIG);
 173                 writel(ptr + HPET_CONFIG, val & ~HPET_CNF_ENABLE);
 174                 return ENXIO;
 175         }
 176
 177         freq = (1000000000000000LL + val / 2) / val;
 178         if (bootverbose) {
 179                 val = readl(ptr + HPET_CAPABILITIES);
 180                 kprintf("acpi_hpet: "
 181                     "vend: 0x%x, rev: 0x%x, num: %d, opts:%s%s\n",
 182                     val >> 16, val & HPET_CAP_REV_ID,
 183                     (val & HPET_CAP_NUM_TIM) >> 8,
 184                     (val & HPET_CAP_LEG_RT) ? " legacy_route" : "",
 185                     (val & HPET_CAP_COUNT_SIZE) ? " 64-bit" : "");
 186         }
 187
 188 #if 0
 189         if (ktestenv("debug.acpi.hpet_test"))
 190                 acpi_hpet_test(sc);
 191 #endif
 192
 193         /*
 194          * Don't attach if the timer never increments.  Since the spec
 195          * requires it to be at least 10 MHz, it has to change in 1 us.
 196          */
 197         val = readl(ptr + HPET_MAIN_COUNTER);
 198         /* This delay correspond to 1us, even at 6 GHz TSC. */
 199         old_tsc = rdtsc();
 200         do {
 201                 cpu_pause();
 202                 new_tsc = rdtsc();
 203         } while (new_tsc - old_tsc < 6000);
 204         val2 = readl(ptr + HPET_MAIN_COUNTER);
 205         if (val == val2) {
 206                 kprintf("acpi_hpet: HPET never increments, disabling\n");
 207                 val = readl(ptr + HPET_CONFIG);
 208                 writel(ptr + HPET_CONFIG, val & ~HPET_CNF_ENABLE);
 209                 return ENXIO;
 210         }
 211
 212         val = readl(ptr + HPET_CONFIG);
 213         writel(ptr + HPET_CONFIG, val & ~HPET_CNF_ENABLE);
 214         acpi_hpet_timer.freq = freq;
 215         kprintf("acpi_hpet: frequency %u\n", acpi_hpet_timer.freq);
 216
 217         acpi_hpet_timer.count = acpi_hpet_early_get_timecount;
 218         acpi_hpet_timer.construct = acpi_hpet_early_construct;
 219         acpi_hpet_timer.destruct = acpi_hpet_early_destruct;
 220
 221         cputimer_register(&acpi_hpet_timer);
 222         cputimer_select(&acpi_hpet_timer, 0);
 223         return 0;
 224 }
 225
 226 static void
 227 acpi_hpet_cputimer_register(void)
 228 {
 229         ACPI_TABLE_HPET *hpet;
 230         vm_paddr_t hpet_paddr;
 231
 232         if (acpi_hpet_for_calibration == 0)
 233                 return;
 234
 235         if (acpi_disabled("hpet"))
 236                 return;
 237
 238         hpet_paddr = sdt_search(ACPI_SIG_HPET);
 239         if (hpet_paddr == 0) {
 240                 if (bootverbose)
 241                         kprintf("acpi_hpet: can't locate HPET\n");
 242                 return;
 243         }
 244
 245         hpet = sdt_sdth_map(hpet_paddr);
 246         if (hpet == NULL)
 247                 return;
 248
 249         if (hpet->Header.Length < 56) {
 250                 kprintf("acpi_hpet: HPET table too short. Length: 0x%x\n",
 251                     hpet->Header.Length);
 252                 return;
 253         }
 254
 255         if (hpet->Sequence != 0) {
 256                 kprintf("acpi_hpet: "
 257                     "HPET table Sequence not 0. Sequence: 0x%x\n", hpet->Id);
 258                 goto done;
 259         }
 260
 261         acpi_hpet_res_start = hpet->Address.Address;
 262         if (acpi_hpet_res_start == 0)
 263                 goto done;
 264
 265         ptr = (vm_offset_t)pmap_mapdev(acpi_hpet_res_start, HPET_MEM_WIDTH);
 266         if (acpi_hpet_early_init() == 0) {
 267                 i8254_cputimer_disable = 1;
 268         } else {
 269                 pmap_unmapdev(ptr, HPET_MEM_WIDTH);
 270                 ptr = 0;
 271         }
 272
 273 done:
 274         sdt_sdth_unmap(&hpet->Header);
 275         return;
 276 }
 277
 278 TIMECOUNTER_INIT(acpi_hpet_init, acpi_hpet_cputimer_register);
 279 #endif
 280
 281 /*
 282  * Locate the ACPI timer using the FADT, set up and allocate the I/O resources
 283  * we will be using.
 284  */
 285 static int
 286 acpi_hpet_identify(driver_t *driver, device_t parent)
 287 {
 288         ACPI_TABLE_HPET *hpet;
 289         ACPI_TABLE_HEADER *hdr;
 290         ACPI_STATUS status;
 291         device_t child;
 292
 293         /*
 294          * Just try once, do nothing if the 'acpi' bus is rescanned.
 295          */
 296         if (device_get_state(parent) == DS_ATTACHED)
 297                 return 0;
 298
 299         ACPI_FUNCTION_TRACE((char *)(uintptr_t) __func__);
 300
 301         /* Only one HPET device can be added. */
 302         if (devclass_get_device(acpi_hpet_devclass, 0))
 303                 return ENXIO;
 304
 305 #if !defined(KLD_MODULE)
 306         if (ptr != 0) {
 307                 /* Use data from early boot for attachment. */
 308                 child = BUS_ADD_CHILD(parent, parent, 0, "acpi_hpet", 0);
 309                 if (child == NULL) {
 310                         device_printf(parent, "%s: can't add acpi_hpet0\n",
 311                             __func__);
 312                         return ENXIO;
 313                 }
 314
 315                 /* Record a magic value so we can detect this device later. */
 316                 acpi_set_magic(child, (uintptr_t)&acpi_hpet_devclass);
 317
 318                 if (bus_set_resource(child, SYS_RES_MEMORY, 0,
 319                     acpi_hpet_res_start, HPET_MEM_WIDTH, -1)) {
 320                         device_printf(child,
 321                             "could not set iomem resources: 0x%jx, %d\n",
 322                             (uintmax_t)acpi_hpet_res_start, HPET_MEM_WIDTH);
 323                         return ENOMEM;
 324                 }
 325
 326                 return 0;
 327         }
 328 #endif
 329
 330         /* Currently, ID and minimum clock tick info is unused. */
 331
 332         status = AcpiGetTable(ACPI_SIG_HPET, 1, &hdr);
 333         if (ACPI_FAILURE(status))
 334                 return ENXIO;
 335
 336         /*
 337          * The unit number could be derived from hdr->Sequence but we only
 338          * support one HPET device.
 339          */
 340         hpet = (ACPI_TABLE_HPET *)hdr;
 341         if (hpet->Sequence != 0) {
 342                 kprintf("ACPI HPET table warning: Sequence is non-zero (%d)\n",
 343                         hpet->Sequence);
 344         }
 345
 346         child = BUS_ADD_CHILD(parent, parent, 0, "acpi_hpet", 0);
 347         if (child == NULL) {
 348                 device_printf(parent, "%s: can't add acpi_hpet0\n", __func__);
 349                 return ENXIO;
 350         }
 351
 352         /* Record a magic value so we can detect this device later. */
 353         acpi_set_magic(child, (uintptr_t)&acpi_hpet_devclass);
 354
 355         acpi_hpet_res_start = hpet->Address.Address;
 356         if (bus_set_resource(child, SYS_RES_MEMORY, 0,
 357                              hpet->Address.Address, HPET_MEM_WIDTH, -1)) {
 358                 device_printf(child, "could not set iomem resources: "
 359                               "0x%jx, %d\n", (uintmax_t)hpet->Address.Address,
 360                               HPET_MEM_WIDTH);
 361                 return ENOMEM;
 362         }
 363         return 0;
 364 }
 365
 366 static int
 367 acpi_hpet_probe(device_t dev)
 368 {
 369         ACPI_FUNCTION_TRACE((char *)(uintptr_t) __func__);
 370
 371         if (acpi_disabled("hpet"))
 372                 return ENXIO;
 373
 374         if (!DEV_HPET(dev) &&
 375             (ACPI_ID_PROBE(device_get_parent(dev), dev, hpet_ids) == NULL ||
 376              device_get_unit(dev) != 0))
 377                 return ENXIO;
 378
 379         device_set_desc(dev, "High Precision Event Timer");
 380         return 0;
 381 }
 382
 383 static int
 384 acpi_hpet_attach(device_t dev)
 385 {
 386         struct acpi_hpet_softc *sc;
 387         int rid;
 388         uint32_t val, val2;
 389         uintmax_t freq;
 390
 391         ACPI_FUNCTION_TRACE((char *)(uintptr_t) __func__);
 392
 393         sc = device_get_softc(dev);
 394         sc->dev = dev;
 395         sc->handle = acpi_get_handle(dev);
 396
 397         rid = 0;
 398         sc->mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid,
 399                                              RF_ACTIVE);
 400         if (sc->mem_res == NULL) {
 401                 /*
 402                  * We only need to make sure that main counter
 403                  * is accessable.
 404                  */
 405                 device_printf(dev, "can't map %dB register space, try %dB\n",
 406                               HPET_MEM_WIDTH, HPET_MEM_WIDTH_MIN);
 407                 rid = 0;
 408                 sc->mem_res = bus_alloc_resource(dev, SYS_RES_MEMORY, &rid,
 409                                 acpi_hpet_res_start,
 410                                 acpi_hpet_res_start + HPET_MEM_WIDTH_MIN - 1,
 411                                 HPET_MEM_WIDTH_MIN, RF_ACTIVE);
 412                 if (sc->mem_res == NULL)
 413                         return ENOMEM;
 414         }
 415
 416         /* Validate that we can access the whole region. */
 417         if (rman_get_size(sc->mem_res) < HPET_MEM_WIDTH_MIN) {
 418                 device_printf(dev, "memory region width %ld too small\n",
 419                               rman_get_size(sc->mem_res));
 420                 bus_release_resource(dev, SYS_RES_MEMORY, rid, sc->mem_res);
 421                 return ENXIO;
 422         }
 423
 424         acpi_hpet_bsh = rman_get_bushandle(sc->mem_res);
 425         acpi_hpet_bst = rman_get_bustag(sc->mem_res);
 426
 427 #if !defined(KLD_MODULE)
 428         if (ptr != 0) {
 429                 /* Use data from early boot for attachment. */
 430                 if (ktestenv("debug.acpi.hpet_test"))
 431                         acpi_hpet_test(sc);
 432                 return 0;
 433         }
 434 #endif
 435
 436         /* Be sure timer is enabled. */
 437         acpi_hpet_enable(sc);
 438
 439         /* Read basic statistics about the timer. */
 440         val = bus_space_read_4(acpi_hpet_bst, acpi_hpet_bsh, HPET_PERIOD);
 441         if (val == 0) {
 442                 device_printf(dev, "invalid period\n");
 443                 acpi_hpet_disable(sc);
 444                 bus_release_resource(dev, SYS_RES_MEMORY, rid, sc->mem_res);
 445                 return ENXIO;
 446         }
 447
 448         freq = (1000000000000000LL + val / 2) / val;
 449         if (bootverbose) {
 450                 val = bus_space_read_4(acpi_hpet_bst, acpi_hpet_bsh,
 451                                        HPET_CAPABILITIES);
 452                 device_printf(dev,
 453                     "vend: 0x%x, rev: 0x%x, num: %d, opts:%s%s\n",
 454                     val >> 16, val & HPET_CAP_REV_ID,
 455                     (val & HPET_CAP_NUM_TIM) >> 8,
 456                     (val & HPET_CAP_LEG_RT) ? " legacy_route" : "",
 457                     (val & HPET_CAP_COUNT_SIZE) ? " 64-bit" : "");
 458         }
 459
 460         if (ktestenv("debug.acpi.hpet_test"))
 461                 acpi_hpet_test(sc);
 462
 463         /*
 464          * Don't attach if the timer never increments.  Since the spec
 465          * requires it to be at least 10 MHz, it has to change in 1 us.
 466          */
 467         val = bus_space_read_4(acpi_hpet_bst, acpi_hpet_bsh,
 468                                HPET_MAIN_COUNTER);
 469         DELAY(1);
 470         val2 = bus_space_read_4(acpi_hpet_bst, acpi_hpet_bsh,
 471                                 HPET_MAIN_COUNTER);
 472         if (val == val2) {
 473                 device_printf(dev, "HPET never increments, disabling\n");
 474                 acpi_hpet_disable(sc);
 475                 bus_release_resource(dev, SYS_RES_MEMORY, rid, sc->mem_res);
 476                 return ENXIO;
 477         }
 478
 479         acpi_hpet_timer.freq = freq;
 480         device_printf(dev, "frequency %u\n", acpi_hpet_timer.freq);
 481
 482         cputimer_register(&acpi_hpet_timer);
 483         cputimer_select(&acpi_hpet_timer, 0);
 484
 485         return 0;
 486 }
 487
 488 /*
 489  * Construct the timer.  Adjust the base so the system clock does not
 490  * jump weirdly.
 491  */
 492 static void
 493 acpi_hpet_construct(struct cputimer *timer, sysclock_t oldclock)
 494 {
 495         timer->base = 0;
 496         timer->base = oldclock - acpi_hpet_get_timecount();
 497 }
 498
 499 static sysclock_t
 500 acpi_hpet_get_timecount(void)
 501 {
 502         return acpi_hpet_read() + acpi_hpet_timer.base;
 503 }
 504
 505 static void
 506 acpi_hpet_enable(struct acpi_hpet_softc *sc)
 507 {
 508         uint32_t val;
 509
 510         val = bus_space_read_4(acpi_hpet_bst, acpi_hpet_bsh, HPET_CONFIG);
 511         bus_space_write_4(acpi_hpet_bst, acpi_hpet_bsh, HPET_CONFIG,
 512                           val | HPET_CNF_ENABLE);
 513 }
 514
 515 static void
 516 acpi_hpet_disable(struct acpi_hpet_softc *sc)
 517 {
 518         uint32_t val;
 519
 520         val = bus_space_read_4(acpi_hpet_bst, acpi_hpet_bsh, HPET_CONFIG);
 521         bus_space_write_4(acpi_hpet_bst, acpi_hpet_bsh, HPET_CONFIG,
 522                           val & ~HPET_CNF_ENABLE);
 523 }
 524
 525 static int
 526 acpi_hpet_suspend(device_t dev)
 527 {
 528         /*
 529          * According to IA-PC HPET specification rev 1.0a
 530          *
 531          * Page 10, 2.3.3:
 532          * "1. The Event Timer registers (including the main counter)
 533          *  are not expected to be preserved through an S3, S4, or S5
 534          *  state."
 535          *
 536          * Page 11, 2.3.3:
 537          * "3. The main counter is permitted, but not required, to run
 538          *  during S1 or S2 states. ..."
 539          *
 540          * These mean we are not allowed to enter any of Sx states,
 541          * if HPET is used as the sys_cputimer.
 542          */
 543         if (sys_cputimer != &acpi_hpet_timer) {
 544                 struct acpi_hpet_softc *sc;
 545
 546                 sc = device_get_softc(dev);
 547                 acpi_hpet_disable(sc);
 548
 549                 return 0;
 550         } else {
 551                 return EOPNOTSUPP;
 552         }
 553 }
 554
 555 static int
 556 acpi_hpet_resume(device_t dev)
 557 {
 558         if (sys_cputimer != &acpi_hpet_timer) {
 559                 struct acpi_hpet_softc *sc;
 560
 561                 sc = device_get_softc(dev);
 562                 acpi_hpet_enable(sc);
 563         }
 564         return 0;
 565 }
 566
 567 /* Print some basic latency/rate information to assist in debugging. */
 568 static void
 569 acpi_hpet_test(struct acpi_hpet_softc *sc)
 570 {
 571         int i;
 572         uint32_t u1, u2;
 573         struct timeval b0, b1, b2;
 574         struct timespec ts;
 575
 576         microuptime(&b0);
 577         microuptime(&b0);
 578         microuptime(&b1);
 579         u1 = bus_space_read_4(acpi_hpet_bst, acpi_hpet_bsh, HPET_MAIN_COUNTER);
 580         for (i = 1; i < 1000; i++) {
 581                 u2 = bus_space_read_4(acpi_hpet_bst, acpi_hpet_bsh,
 582                                       HPET_MAIN_COUNTER);
 583         }
 584         microuptime(&b2);
 585         u2 = bus_space_read_4(acpi_hpet_bst, acpi_hpet_bsh, HPET_MAIN_COUNTER);
 586
 587         timevalsub(&b2, &b1);
 588         timevalsub(&b1, &b0);
 589         timevalsub(&b2, &b1);
 590
 591         TIMEVAL_TO_TIMESPEC(&b2, &ts);
 592
 593         device_printf(sc->dev, "%ld.%09ld: %u ... %u = %u\n",
 594             (long)b2.tv_sec, b2.tv_usec, u1, u2, u2 - u1);
 595
 596         device_printf(sc->dev, "time per call: %ld ns\n", ts.tv_nsec / 1000);
 597 }