sys/dev/acpica/acpi_timer.c

   1 /*-
   2  * Copyright (c) 2000, 2001 Michael Smith
   3  * Copyright (c) 2000 BSDi
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  25  * SUCH DAMAGE.
  26  *
  27  * $FreeBSD: src/sys/dev/acpica/acpi_timer.c,v 1.35 2004/07/22 05:42:14 njl Exp $
  28  */
  29 #include "opt_acpi.h"
  30 #include <sys/param.h>
  31 #include <sys/bus.h>
  32 #include <sys/kernel.h>
  33 #include <sys/module.h>
  34 #include <sys/sysctl.h>
  35 #include <sys/systimer.h>
  36 #include <sys/rman.h>
  37
  38 #include <machine/lock.h>
  39 #include <bus/pci/pcivar.h>
  40
  41 #include "acpi.h"
  42 #include "accommon.h"
  43 #include "acpivar.h"
  44
  45 /*
  46  * A timecounter based on the free-running ACPI timer.
  47  *
  48  * Based on the i386-only mp_clock.c by <phk@FreeBSD.ORG>.
  49  */
  50
  51 /* Hooks for the ACPICA debugging infrastructure */
  52 #define _COMPONENT      ACPI_TIMER
  53 ACPI_MODULE_NAME("TIMER")
  54
  55 static device_t                 acpi_timer_dev;
  56 static UINT32                   acpi_timer_resolution;
  57
  58 static sysclock_t acpi_timer_get_timecount(void);
  59 static sysclock_t acpi_timer_get_timecount24(void);
  60 static sysclock_t acpi_timer_get_timecount_safe(void);
  61 static void acpi_timer_construct(struct cputimer *timer, sysclock_t oldclock);
  62
  63 static struct cputimer acpi_cputimer = {
  64         .next           = SLIST_ENTRY_INITIALIZER,
  65         .name           = "ACPI",
  66         .pri            = CPUTIMER_PRI_ACPI,
  67         .type           = CPUTIMER_ACPI,
  68         .count          = acpi_timer_get_timecount_safe,
  69         .fromhz         = cputimer_default_fromhz,
  70         .fromus         = cputimer_default_fromus,
  71         .construct      = acpi_timer_construct,
  72         .destruct       = cputimer_default_destruct,
  73         .freq           = ACPI_PM_TIMER_FREQUENCY
  74 };
  75
  76 static int      acpi_timer_identify(driver_t *driver, device_t parent);
  77 static int      acpi_timer_probe(device_t dev);
  78 static int      acpi_timer_attach(device_t dev);
  79 static int      acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS);
  80
  81 static int      acpi_timer_test(void);
  82
  83 static device_method_t acpi_timer_methods[] = {
  84     DEVMETHOD(device_identify,  acpi_timer_identify),
  85     DEVMETHOD(device_probe,     acpi_timer_probe),
  86     DEVMETHOD(device_attach,    acpi_timer_attach),
  87
  88     DEVMETHOD_END
  89 };
  90
  91 static driver_t acpi_timer_driver = {
  92     "acpi_timer",
  93     acpi_timer_methods,
  94     0,
  95     .gpri = KOBJ_GPRI_ACPI+2
  96 };
  97
  98 static devclass_t acpi_timer_devclass;
  99 DRIVER_MODULE(acpi_timer, acpi, acpi_timer_driver, acpi_timer_devclass, NULL, NULL);
 100 MODULE_DEPEND(acpi_timer, acpi, 1, 1, 1);
 101
 102 /*
 103  * Locate the ACPI timer using the FADT, set up and allocate the I/O resources
 104  * we will be using.
 105  */
 106 static int
 107 acpi_timer_identify(driver_t *driver, device_t parent)
 108 {
 109     device_t dev;
 110
 111     /*
 112      * Just try once, do nothing if the 'acpi' bus is rescanned.
 113      */
 114     if (device_get_state(parent) == DS_ATTACHED)
 115         return (0);
 116
 117     ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
 118
 119     if (acpi_disabled("timer") || (acpi_quirks & ACPI_Q_TIMER) ||
 120         acpi_timer_dev)
 121         return (ENXIO);
 122
 123     if ((dev = BUS_ADD_CHILD(parent, parent, 0, "acpi_timer", 0)) == NULL) {
 124         device_printf(parent, "could not add acpi_timer0\n");
 125         return (ENXIO);
 126     }
 127     acpi_timer_dev = dev;
 128
 129     return (0);
 130 }
 131
 132 static int
 133 acpi_timer_probe(device_t dev)
 134 {
 135     ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
 136
 137     if (dev != acpi_timer_dev)
 138         return (ENXIO);
 139
 140     if (ACPI_FAILURE(AcpiGetTimerResolution(&acpi_timer_resolution)))
 141         return (ENXIO);
 142
 143     return (0);
 144 }
 145
 146 static int
 147 acpi_timer_attach(device_t dev)
 148 {
 149     char desc[40];
 150     int i, j;
 151
 152     ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
 153
 154     /*
 155      * If all tests of the counter succeed, use the ACPI-fast method.  If
 156      * at least one failed, default to using the safe routine, which reads
 157      * the timer multiple times to get a consistent value before returning.
 158      */
 159     j = 0;
 160     for (i = 0; i < 10; i++)
 161         j += acpi_timer_test();
 162     if (j == 10) {
 163         if (acpi_timer_resolution == 32) {
 164             acpi_cputimer.name = "ACPI-fast";
 165             acpi_cputimer.count = acpi_timer_get_timecount;
 166         } else {
 167             acpi_cputimer.name = "ACPI-fast24";
 168             acpi_cputimer.count = acpi_timer_get_timecount24;
 169         }
 170     } else {
 171         if (acpi_timer_resolution == 32)
 172             acpi_cputimer.name = "ACPI-safe";
 173         else
 174             acpi_cputimer.name = "ACPI-safe24";
 175         acpi_cputimer.count = acpi_timer_get_timecount_safe;
 176     }
 177
 178     ksprintf(desc, "%u-bit timer at 3.579545MHz", acpi_timer_resolution);
 179     device_set_desc_copy(dev, desc);
 180
 181     cputimer_register(&acpi_cputimer);
 182     cputimer_select(&acpi_cputimer, 0);
 183
 184     return (0);
 185 }
 186
 187 /*
 188  * Construct the timer.  Adjust the base so the system clock does not
 189  * jump weirdly.
 190  */
 191 static void
 192 acpi_timer_construct(struct cputimer *timer, sysclock_t oldclock)
 193 {
 194     timer->base = 0;
 195     timer->base = oldclock - acpi_timer_get_timecount_safe();
 196 }
 197
 198 /*
 199  * Fetch current time value from reliable hardware.
 200  *
 201  * The cputimer interface requires a 32 bit return value.  If the ACPI timer
 202  * is only 24 bits then we have to keep track of the upper 8 bits on our
 203  * own.
 204  *
 205  * per-cpu tracking fields can cause problems on VMs if one or more cpus
 206  * stalls long-enough for the timer to turn-over twice, so instead optimize
 207  * the locking case by not updating acpi_cputimer.base until the timer
 208  * has gone more than 1/16 its full range.
 209  *
 210  * These are horrible hacks, but at least the SMP interference is minimal
 211  * with them.  Note that just reading the ACPI timer itself represents a
 212  * bottleneck due to the slow I/O.
 213  */
 214 static sysclock_t
 215 acpi_timer_get_timecount24(void)
 216 {
 217     sysclock_t last_counter;
 218     sysclock_t next_counter;
 219     uint32_t counter;
 220
 221     last_counter = acpi_cputimer.base;
 222     for (;;) {
 223             cpu_ccfence();
 224             AcpiGetTimer(&counter);
 225             if (counter < (last_counter & 0x00FFFFFFU))
 226                 next_counter = ((last_counter + 0x01000000U) &
 227                                 0xFFFFFFFFFF000000LU) | counter;
 228             else
 229                 next_counter = (last_counter &
 230                                 0xFFFFFFFFFF000000LU) | counter;
 231             if (atomic_fcmpset_long(&acpi_cputimer.base, &last_counter,
 232                                     next_counter)) {
 233                 break;
 234             }
 235     }
 236     return next_counter;
 237 }
 238
 239 static sysclock_t
 240 acpi_timer_get_timecount(void)
 241 {
 242     sysclock_t last_counter;
 243     sysclock_t next_counter;
 244     uint32_t counter;
 245
 246     last_counter = acpi_cputimer.base;
 247     for (;;) {
 248             cpu_ccfence();
 249             AcpiGetTimer(&counter);
 250             if (counter < (last_counter & 0xFFFFFFFFU))
 251                 next_counter = ((last_counter + 0x0100000000U) &
 252                                 0xFFFFFFFF00000000LU) | counter;
 253             else
 254                 next_counter = (last_counter &
 255                                 0xFFFFFFFF00000000LU) | counter;
 256             if (atomic_fcmpset_long(&acpi_cputimer.base, &last_counter,
 257                                     next_counter)) {
 258                 break;
 259             }
 260     }
 261     return next_counter;
 262 }
 263
 264 /*
 265  * Fetch current time value from hardware that may not correctly
 266  * latch the counter.  We need to read until we have three monotonic
 267  * samples and then use the middle one, otherwise we are not protected
 268  * against the fact that the bits can be wrong in two directions.  If
 269  * we only cared about monosity, two reads would be enough.
 270  */
 271 static __inline sysclock_t
 272 _acpi_timer_get_timecount_safe(void)
 273 {
 274     u_int u1, u2, u3;
 275
 276     AcpiGetTimer(&u2);
 277     AcpiGetTimer(&u3);
 278     do {
 279         u1 = u2;
 280         u2 = u3;
 281         AcpiGetTimer(&u3);
 282     } while (u1 > u2 || u2 > u3);
 283
 284     return (u2);
 285 }
 286
 287 static sysclock_t
 288 acpi_timer_get_timecount_safe(void)
 289 {
 290     sysclock_t last_counter;
 291     sysclock_t next_counter;
 292     uint32_t counter;
 293
 294     last_counter = acpi_cputimer.base;
 295     for (;;) {
 296             cpu_ccfence();
 297             counter = _acpi_timer_get_timecount_safe();
 298
 299             if (acpi_timer_resolution == 32) {
 300                     if (counter < (last_counter & 0xFFFFFFFFU))
 301                         next_counter = ((last_counter + 0x0100000000U) &
 302                                         0xFFFFFFFF00000000LU) | counter;
 303                     else
 304                         next_counter = (last_counter &
 305                                         0xFFFFFFFF00000000LU) | counter;
 306             } else {
 307                     if (counter < (last_counter & 0x00FFFFFFU))
 308                         next_counter = ((last_counter + 0x01000000U) &
 309                                         0xFFFFFFFFFF000000LU) | counter;
 310                     else
 311                         next_counter = (last_counter &
 312                                         0xFFFFFFFFFF000000LU) | counter;
 313             }
 314             if (atomic_fcmpset_long(&acpi_cputimer.base, &last_counter,
 315                                     next_counter)) {
 316                 break;
 317             }
 318     }
 319     return next_counter;
 320 }
 321
 322 /*
 323  * Timecounter freqency adjustment interface.
 324  */
 325 static int
 326 acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS)
 327 {
 328     int error;
 329     u_int freq;
 330
 331     if (acpi_cputimer.freq == 0)
 332         return (EOPNOTSUPP);
 333     freq = acpi_cputimer.freq;
 334     error = sysctl_handle_int(oidp, &freq, 0, req);
 335     if (error == 0 && req->newptr != NULL)
 336         cputimer_set_frequency(&acpi_cputimer, freq);
 337
 338     return (error);
 339 }
 340
 341 SYSCTL_PROC(_machdep, OID_AUTO, acpi_timer_freq, CTLTYPE_INT | CTLFLAG_RW,
 342     0, sizeof(u_int), acpi_timer_sysctl_freq, "I", "ACPI timer frequency");
 343
 344 /*
 345  * Some ACPI timers are known or believed to suffer from implementation
 346  * problems which can lead to erroneous values being read.  This function
 347  * tests for consistent results from the timer and returns 1 if it believes
 348  * the timer is consistent, otherwise it returns 0.
 349  *
 350  * It appears the cause is that the counter is not latched to the PCI bus
 351  * clock when read:
 352  *
 353  * ] 20. ACPI Timer Errata
 354  * ]
 355  * ]   Problem: The power management timer may return improper result when
 356  * ]   read. Although the timer value settles properly after incrementing,
 357  * ]   while incrementing there is a 3nS window every 69.8nS where the
 358  * ]   timer value is indeterminate (a 4.2% chance that the data will be
 359  * ]   incorrect when read). As a result, the ACPI free running count up
 360  * ]   timer specification is violated due to erroneous reads.  Implication:
 361  * ]   System hangs due to the "inaccuracy" of the timer when used by
 362  * ]   software for time critical events and delays.
 363  * ]
 364  * ] Workaround: Read the register twice and compare.
 365  * ] Status: This will not be fixed in the PIIX4 or PIIX4E, it is fixed
 366  * ] in the PIIX4M.
 367  */
 368
 369 static int
 370 acpi_timer_test(void)
 371 {
 372     uint32_t    last, this;
 373     int         min, max, max2, n, delta;
 374     register_t  s;
 375
 376     min = INT32_MAX;
 377     max = max2 = 0;
 378
 379     /* Test the timer with interrupts disabled to get accurate results. */
 380 #if defined(__x86_64__)
 381     s = read_rflags();
 382 #else
 383 #error "no read_*flags"
 384 #endif
 385     cpu_disable_intr();
 386     AcpiGetTimer(&last);
 387     for (n = 0; n < 2000; n++) {
 388         AcpiGetTimer(&this);
 389         delta = acpi_TimerDelta(this, last);
 390         if (delta > max) {
 391             max2 = max;
 392             max = delta;
 393         } else if (delta > max2) {
 394             max2 = delta;
 395         }
 396         if (delta < min)
 397             min = delta;
 398         last = this;
 399     }
 400     /* cpu_enable_intr(); restored to original by write_rflags() */
 401 #if defined(__x86_64__)
 402     write_rflags(s);
 403 #else
 404 #error "no read_*flags"
 405 #endif
 406
 407     delta = max2 - min;
 408     if ((max - min > 8 || delta > 3) && vmm_guest == VMM_GUEST_NONE)
 409         n = 0;
 410     else if (min < 0 || max == 0 || max2 == 0)
 411         n = 0;
 412     else
 413         n = 1;
 414     if (bootverbose) {
 415         kprintf("ACPI timer looks %s min = %d, max = %d, width = %d\n",
 416                 n ? "GOOD" : "BAD ",
 417                 min, max, max - min);
 418     }
 419
 420     return (n);
 421 }