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         SLIST_ENTRY_INITIALIZER,
  66         "ACPI",
  67         CPUTIMER_PRI_ACPI,
  68         CPUTIMER_ACPI,
  69         acpi_timer_get_timecount_safe,
  70         cputimer_default_fromhz,
  71         cputimer_default_fromus,
  72         acpi_timer_construct,
  73         cputimer_default_destruct,
  74         ACPI_PM_TIMER_FREQUENCY,
  75         0, 0, 0
  76 };
  77
  78 static int      acpi_timer_identify(driver_t *driver, device_t parent);
  79 static int      acpi_timer_probe(device_t dev);
  80 static int      acpi_timer_attach(device_t dev);
  81 static int      acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS);
  82
  83 static int      acpi_timer_test(void);
  84
  85 static device_method_t acpi_timer_methods[] = {
  86     DEVMETHOD(device_identify,  acpi_timer_identify),
  87     DEVMETHOD(device_probe,     acpi_timer_probe),
  88     DEVMETHOD(device_attach,    acpi_timer_attach),
  89
  90     DEVMETHOD_END
  91 };
  92
  93 static driver_t acpi_timer_driver = {
  94     "acpi_timer",
  95     acpi_timer_methods,
  96     0,
  97 };
  98
  99 static devclass_t acpi_timer_devclass;
 100 DRIVER_MODULE(acpi_timer, acpi, acpi_timer_driver, acpi_timer_devclass, NULL, NULL);
 101 MODULE_DEPEND(acpi_timer, acpi, 1, 1, 1);
 102
 103 /*
 104  * Locate the ACPI timer using the FADT, set up and allocate the I/O resources
 105  * we will be using.
 106  */
 107 static int
 108 acpi_timer_identify(driver_t *driver, device_t parent)
 109 {
 110     device_t dev;
 111
 112     /*
 113      * Just try once, do nothing if the 'acpi' bus is rescanned.
 114      */
 115     if (device_get_state(parent) == DS_ATTACHED)
 116         return (0);
 117
 118     ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
 119
 120     if (acpi_disabled("timer") || (acpi_quirks & ACPI_Q_TIMER) ||
 121         acpi_timer_dev)
 122         return (ENXIO);
 123
 124     if ((dev = BUS_ADD_CHILD(parent, parent, 0, "acpi_timer", 0)) == NULL) {
 125         device_printf(parent, "could not add acpi_timer0\n");
 126         return (ENXIO);
 127     }
 128     acpi_timer_dev = dev;
 129
 130     return (0);
 131 }
 132
 133 static int
 134 acpi_timer_probe(device_t dev)
 135 {
 136     ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
 137
 138     if (dev != acpi_timer_dev)
 139         return (ENXIO);
 140
 141     if (ACPI_FAILURE(AcpiGetTimerResolution(&acpi_timer_resolution)))
 142         return (ENXIO);
 143
 144     return (0);
 145 }
 146
 147 static int
 148 acpi_timer_attach(device_t dev)
 149 {
 150     char desc[40];
 151     int i, j;
 152
 153     ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
 154
 155     /*
 156      * If all tests of the counter succeed, use the ACPI-fast method.  If
 157      * at least one failed, default to using the safe routine, which reads
 158      * the timer multiple times to get a consistent value before returning.
 159      */
 160     j = 0;
 161     for (i = 0; i < 10; i++)
 162         j += acpi_timer_test();
 163     if (j == 10) {
 164         if (acpi_timer_resolution == 32) {
 165             acpi_cputimer.name = "ACPI-fast";
 166             acpi_cputimer.count = acpi_timer_get_timecount;
 167         } else {
 168             acpi_cputimer.name = "ACPI-fast24";
 169             acpi_cputimer.count = acpi_timer_get_timecount24;
 170         }
 171     } else {
 172         if (acpi_timer_resolution == 32)
 173             acpi_cputimer.name = "ACPI-safe";
 174         else
 175             acpi_cputimer.name = "ACPI-safe24";
 176         acpi_cputimer.count = acpi_timer_get_timecount_safe;
 177     }
 178
 179     ksprintf(desc, "%u-bit timer at 3.579545MHz", acpi_timer_resolution);
 180     device_set_desc_copy(dev, desc);
 181
 182     cputimer_register(&acpi_cputimer);
 183     cputimer_select(&acpi_cputimer, 0);
 184
 185     return (0);
 186 }
 187
 188 /*
 189  * Construct the timer.  Adjust the base so the system clock does not
 190  * jump weirdly.
 191  */
 192 static void
 193 acpi_timer_construct(struct cputimer *timer, sysclock_t oldclock)
 194 {
 195     timer->base = 0;
 196     timer->base = oldclock - acpi_timer_get_timecount_safe();
 197 }
 198
 199 /*
 200  * Fetch current time value from reliable hardware.
 201  *
 202  * The cputimer interface requires a 32 bit return value.  If the ACPI timer
 203  * is only 24 bits then we have to keep track of the upper 8 bits on our
 204  * own.
 205  *
 206  * XXX we could probably get away with using a per-cpu field for this and
 207  * just use interrupt disablement instead of clock_lock.
 208  */
 209 static sysclock_t
 210 acpi_timer_get_timecount24(void)
 211 {
 212     sysclock_t counter;
 213
 214     clock_lock();
 215     AcpiGetTimer(&counter);
 216     if (counter < acpi_last_counter)
 217         acpi_cputimer.base += 0x01000000;
 218     acpi_last_counter = counter;
 219     counter += acpi_cputimer.base;
 220     clock_unlock();
 221     return (counter);
 222 }
 223
 224 static sysclock_t
 225 acpi_timer_get_timecount(void)
 226 {
 227     sysclock_t counter;
 228
 229     AcpiGetTimer(&counter);
 230     return (counter + acpi_cputimer.base);
 231 }
 232
 233 /*
 234  * Fetch current time value from hardware that may not correctly
 235  * latch the counter.  We need to read until we have three monotonic
 236  * samples and then use the middle one, otherwise we are not protected
 237  * against the fact that the bits can be wrong in two directions.  If
 238  * we only cared about monosity, two reads would be enough.
 239  */
 240 static sysclock_t
 241 acpi_timer_get_timecount_safe(void)
 242 {
 243     u_int u1, u2, u3;
 244
 245     if (acpi_timer_resolution != 32)
 246         clock_lock();
 247
 248     AcpiGetTimer(&u2);
 249     AcpiGetTimer(&u3);
 250     do {
 251         u1 = u2;
 252         u2 = u3;
 253         AcpiGetTimer(&u3);
 254     } while (u1 > u2 || u2 > u3);
 255
 256     if (acpi_timer_resolution != 32) {
 257         if (u2 < acpi_last_counter)
 258             acpi_cputimer.base += 0x01000000;
 259         acpi_last_counter = u2;
 260         clock_unlock();
 261     }
 262     return (u2 + acpi_cputimer.base);
 263 }
 264
 265 /*
 266  * Timecounter freqency adjustment interface.
 267  */
 268 static int
 269 acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS)
 270 {
 271     int error;
 272     u_int freq;
 273
 274     if (acpi_cputimer.freq == 0)
 275         return (EOPNOTSUPP);
 276     freq = acpi_cputimer.freq;
 277     error = sysctl_handle_int(oidp, &freq, 0, req);
 278     if (error == 0 && req->newptr != NULL)
 279         cputimer_set_frequency(&acpi_cputimer, freq);
 280
 281     return (error);
 282 }
 283
 284 SYSCTL_PROC(_machdep, OID_AUTO, acpi_timer_freq, CTLTYPE_INT | CTLFLAG_RW,
 285     0, sizeof(u_int), acpi_timer_sysctl_freq, "I", "ACPI timer frequency");
 286
 287 /*
 288  * Some ACPI timers are known or believed to suffer from implementation
 289  * problems which can lead to erroneous values being read.  This function
 290  * tests for consistent results from the timer and returns 1 if it believes
 291  * the timer is consistent, otherwise it returns 0.
 292  *
 293  * It appears the cause is that the counter is not latched to the PCI bus
 294  * clock when read:
 295  *
 296  * ] 20. ACPI Timer Errata
 297  * ]
 298  * ]   Problem: The power management timer may return improper result when
 299  * ]   read. Although the timer value settles properly after incrementing,
 300  * ]   while incrementing there is a 3nS window every 69.8nS where the
 301  * ]   timer value is indeterminate (a 4.2% chance that the data will be
 302  * ]   incorrect when read). As a result, the ACPI free running count up
 303  * ]   timer specification is violated due to erroneous reads.  Implication:
 304  * ]   System hangs due to the "inaccuracy" of the timer when used by
 305  * ]   software for time critical events and delays.
 306  * ]
 307  * ] Workaround: Read the register twice and compare.
 308  * ] Status: This will not be fixed in the PIIX4 or PIIX4E, it is fixed
 309  * ] in the PIIX4M.
 310  */
 311
 312 static int
 313 acpi_timer_test(void)
 314 {
 315     uint32_t    last, this;
 316     int         min, max, max2, n, delta;
 317     register_t  s;
 318
 319     min = INT32_MAX;
 320     max = max2 = 0;
 321
 322     /* Test the timer with interrupts disabled to get accurate results. */
 323 #if defined(__x86_64__)
 324     s = read_rflags();
 325 #else
 326 #error "no read_*flags"
 327 #endif
 328     cpu_disable_intr();
 329     AcpiGetTimer(&last);
 330     for (n = 0; n < 2000; n++) {
 331         AcpiGetTimer(&this);
 332         delta = acpi_TimerDelta(this, last);
 333         if (delta > max) {
 334             max2 = max;
 335             max = delta;
 336         } else if (delta > max2) {
 337             max2 = delta;
 338         }
 339         if (delta < min)
 340             min = delta;
 341         last = this;
 342     }
 343     /* cpu_enable_intr(); restored to original by write_rflags() */
 344 #if defined(__x86_64__)
 345     write_rflags(s);
 346 #else
 347 #error "no read_*flags"
 348 #endif
 349
 350     delta = max2 - min;
 351     if ((max - min > 8 || delta > 3) && vmm_guest == VMM_GUEST_NONE)
 352         n = 0;
 353     else if (min < 0 || max == 0 || max2 == 0)
 354         n = 0;
 355     else
 356         n = 1;
 357     if (bootverbose) {
 358         kprintf("ACPI timer looks %s min = %d, max = %d, width = %d\n",
 359                 n ? "GOOD" : "BAD ",
 360                 min, max, max - min);
 361     }
 362
 363     return (n);
 364 }