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 static sysclock_t               acpi_last_counter;
  58
  59 static sysclock_t acpi_timer_get_timecount(void);
  60 static sysclock_t acpi_timer_get_timecount24(void);
  61 static sysclock_t acpi_timer_get_timecount_safe(void);
  62 static void acpi_timer_construct(struct cputimer *timer, sysclock_t oldclock);
  63
  64 static struct cputimer acpi_cputimer = {
  65         .next           = SLIST_ENTRY_INITIALIZER,
  66         .name           = "ACPI",
  67         .pri            = CPUTIMER_PRI_ACPI,
  68         .type           = CPUTIMER_ACPI,
  69         .count          = acpi_timer_get_timecount_safe,
  70         .fromhz         = cputimer_default_fromhz,
  71         .fromus         = cputimer_default_fromus,
  72         .construct      = acpi_timer_construct,
  73         .destruct       = cputimer_default_destruct,
  74         .freq           = ACPI_PM_TIMER_FREQUENCY
  75 };
  76
  77 static int      acpi_timer_identify(driver_t *driver, device_t parent);
  78 static int      acpi_timer_probe(device_t dev);
  79 static int      acpi_timer_attach(device_t dev);
  80 static int      acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS);
  81
  82 static int      acpi_timer_test(void);
  83
  84 static device_method_t acpi_timer_methods[] = {
  85     DEVMETHOD(device_identify,  acpi_timer_identify),
  86     DEVMETHOD(device_probe,     acpi_timer_probe),
  87     DEVMETHOD(device_attach,    acpi_timer_attach),
  88
  89     DEVMETHOD_END
  90 };
  91
  92 static driver_t acpi_timer_driver = {
  93     "acpi_timer",
  94     acpi_timer_methods,
  95     0,
  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  * XXX we could probably get away with using a per-cpu field for this and
 206  * just use interrupt disablement instead of clock_lock.
 207  */
 208 static sysclock_t
 209 acpi_timer_get_timecount24(void)
 210 {
 211     sysclock_t counter;
 212
 213     clock_lock();
 214     AcpiGetTimer(&counter);
 215     if (counter < acpi_last_counter)
 216         acpi_cputimer.base += 0x01000000;
 217     acpi_last_counter = counter;
 218     counter += acpi_cputimer.base;
 219     clock_unlock();
 220     return (counter);
 221 }
 222
 223 static sysclock_t
 224 acpi_timer_get_timecount(void)
 225 {
 226     sysclock_t counter;
 227
 228     AcpiGetTimer(&counter);
 229     return (counter + acpi_cputimer.base);
 230 }
 231
 232 /*
 233  * Fetch current time value from hardware that may not correctly
 234  * latch the counter.  We need to read until we have three monotonic
 235  * samples and then use the middle one, otherwise we are not protected
 236  * against the fact that the bits can be wrong in two directions.  If
 237  * we only cared about monosity, two reads would be enough.
 238  */
 239 static sysclock_t
 240 acpi_timer_get_timecount_safe(void)
 241 {
 242     u_int u1, u2, u3;
 243
 244     if (acpi_timer_resolution != 32)
 245         clock_lock();
 246
 247     AcpiGetTimer(&u2);
 248     AcpiGetTimer(&u3);
 249     do {
 250         u1 = u2;
 251         u2 = u3;
 252         AcpiGetTimer(&u3);
 253     } while (u1 > u2 || u2 > u3);
 254
 255     if (acpi_timer_resolution != 32) {
 256         if (u2 < acpi_last_counter)
 257             acpi_cputimer.base += 0x01000000;
 258         acpi_last_counter = u2;
 259         clock_unlock();
 260     }
 261     return (u2 + acpi_cputimer.base);
 262 }
 263
 264 /*
 265  * Timecounter freqency adjustment interface.
 266  */
 267 static int
 268 acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS)
 269 {
 270     int error;
 271     u_int freq;
 272
 273     if (acpi_cputimer.freq == 0)
 274         return (EOPNOTSUPP);
 275     freq = acpi_cputimer.freq;
 276     error = sysctl_handle_int(oidp, &freq, 0, req);
 277     if (error == 0 && req->newptr != NULL)
 278         cputimer_set_frequency(&acpi_cputimer, freq);
 279
 280     return (error);
 281 }
 282
 283 SYSCTL_PROC(_machdep, OID_AUTO, acpi_timer_freq, CTLTYPE_INT | CTLFLAG_RW,
 284     0, sizeof(u_int), acpi_timer_sysctl_freq, "I", "ACPI timer frequency");
 285
 286 /*
 287  * Some ACPI timers are known or believed to suffer from implementation
 288  * problems which can lead to erroneous values being read.  This function
 289  * tests for consistent results from the timer and returns 1 if it believes
 290  * the timer is consistent, otherwise it returns 0.
 291  *
 292  * It appears the cause is that the counter is not latched to the PCI bus
 293  * clock when read:
 294  *
 295  * ] 20. ACPI Timer Errata
 296  * ]
 297  * ]   Problem: The power management timer may return improper result when
 298  * ]   read. Although the timer value settles properly after incrementing,
 299  * ]   while incrementing there is a 3nS window every 69.8nS where the
 300  * ]   timer value is indeterminate (a 4.2% chance that the data will be
 301  * ]   incorrect when read). As a result, the ACPI free running count up
 302  * ]   timer specification is violated due to erroneous reads.  Implication:
 303  * ]   System hangs due to the "inaccuracy" of the timer when used by
 304  * ]   software for time critical events and delays.
 305  * ]
 306  * ] Workaround: Read the register twice and compare.
 307  * ] Status: This will not be fixed in the PIIX4 or PIIX4E, it is fixed
 308  * ] in the PIIX4M.
 309  */
 310
 311 static int
 312 acpi_timer_test(void)
 313 {
 314     uint32_t    last, this;
 315     int         min, max, max2, n, delta;
 316     register_t  s;
 317
 318     min = INT32_MAX;
 319     max = max2 = 0;
 320
 321     /* Test the timer with interrupts disabled to get accurate results. */
 322 #if defined(__x86_64__)
 323     s = read_rflags();
 324 #else
 325 #error "no read_*flags"
 326 #endif
 327     cpu_disable_intr();
 328     AcpiGetTimer(&last);
 329     for (n = 0; n < 2000; n++) {
 330         AcpiGetTimer(&this);
 331         delta = acpi_TimerDelta(this, last);
 332         if (delta > max) {
 333             max2 = max;
 334             max = delta;
 335         } else if (delta > max2) {
 336             max2 = delta;
 337         }
 338         if (delta < min)
 339             min = delta;
 340         last = this;
 341     }
 342     /* cpu_enable_intr(); restored to original by write_rflags() */
 343 #if defined(__x86_64__)
 344     write_rflags(s);
 345 #else
 346 #error "no read_*flags"
 347 #endif
 348
 349     delta = max2 - min;
 350     if ((max - min > 8 || delta > 3) && vmm_guest == VMM_GUEST_NONE)
 351         n = 0;
 352     else if (min < 0 || max == 0 || max2 == 0)
 353         n = 0;
 354     else
 355         n = 1;
 356     if (bootverbose) {
 357         kprintf("ACPI timer looks %s min = %d, max = %d, width = %d\n",
 358                 n ? "GOOD" : "BAD ",
 359                 min, max, max - min);
 360     }
 361
 362     return (n);
 363 }