The Design and Implementation of the FreeBSD Operating System, Second Edition
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sys/dev/acpica/acpi_timer.c

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    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 
   28 #include <sys/cdefs.h>
   29 __FBSDID("$FreeBSD: releng/10.4/sys/dev/acpica/acpi_timer.c 255726 2013-09-20 05:06:03Z gibbs $");
   30 
   31 #include "opt_acpi.h"
   32 #include <sys/param.h>
   33 #include <sys/bus.h>
   34 #include <sys/eventhandler.h>
   35 #include <sys/kernel.h>
   36 #include <sys/module.h>
   37 #include <sys/sysctl.h>
   38 #include <sys/timetc.h>
   39 
   40 #include <machine/bus.h>
   41 #include <machine/resource.h>
   42 #include <sys/rman.h>
   43 
   44 #include <contrib/dev/acpica/include/acpi.h>
   45 #include <contrib/dev/acpica/include/accommon.h>
   46 
   47 #include <dev/acpica/acpivar.h>
   48 #include <dev/pci/pcivar.h>
   49 
   50 /*
   51  * A timecounter based on the free-running ACPI timer.
   52  *
   53  * Based on the i386-only mp_clock.c by <phk@FreeBSD.ORG>.
   54  */
   55 
   56 /* Hooks for the ACPI CA debugging infrastructure */
   57 #define _COMPONENT      ACPI_TIMER
   58 ACPI_MODULE_NAME("TIMER")
   59 
   60 static device_t                 acpi_timer_dev;
   61 static struct resource          *acpi_timer_reg;
   62 static bus_space_handle_t       acpi_timer_bsh;
   63 static bus_space_tag_t          acpi_timer_bst;
   64 static eventhandler_tag         acpi_timer_eh;
   65 
   66 static u_int    acpi_timer_frequency = 14318182 / 4;
   67 
   68 static void     acpi_timer_identify(driver_t *driver, device_t parent);
   69 static int      acpi_timer_probe(device_t dev);
   70 static int      acpi_timer_attach(device_t dev);
   71 static void     acpi_timer_resume_handler(struct timecounter *);
   72 static void     acpi_timer_suspend_handler(struct timecounter *);
   73 static u_int    acpi_timer_get_timecount(struct timecounter *tc);
   74 static u_int    acpi_timer_get_timecount_safe(struct timecounter *tc);
   75 static int      acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS);
   76 static void     acpi_timer_boot_test(void);
   77 
   78 static int      acpi_timer_test(void);
   79 
   80 static device_method_t acpi_timer_methods[] = {
   81     DEVMETHOD(device_identify,  acpi_timer_identify),
   82     DEVMETHOD(device_probe,     acpi_timer_probe),
   83     DEVMETHOD(device_attach,    acpi_timer_attach),
   84 
   85     DEVMETHOD_END
   86 };
   87 
   88 static driver_t acpi_timer_driver = {
   89     "acpi_timer",
   90     acpi_timer_methods,
   91     0,
   92 };
   93 
   94 static devclass_t acpi_timer_devclass;
   95 DRIVER_MODULE(acpi_timer, acpi, acpi_timer_driver, acpi_timer_devclass, 0, 0);
   96 MODULE_DEPEND(acpi_timer, acpi, 1, 1, 1);
   97 
   98 static struct timecounter acpi_timer_timecounter = {
   99         acpi_timer_get_timecount_safe,  /* get_timecount function */
  100         0,                              /* no poll_pps */
  101         0,                              /* no default counter_mask */
  102         0,                              /* no default frequency */
  103         "ACPI",                         /* name */
  104         -1                              /* quality (chosen later) */
  105 };
  106 
  107 static __inline uint32_t
  108 acpi_timer_read(void)
  109 {
  110 
  111     return (bus_space_read_4(acpi_timer_bst, acpi_timer_bsh, 0));
  112 }
  113 
  114 /*
  115  * Locate the ACPI timer using the FADT, set up and allocate the I/O resources
  116  * we will be using.
  117  */
  118 static void
  119 acpi_timer_identify(driver_t *driver, device_t parent)
  120 {
  121     device_t dev;
  122     u_long rlen, rstart;
  123     int rid, rtype;
  124 
  125     ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
  126 
  127     if (acpi_disabled("timer") || (acpi_quirks & ACPI_Q_TIMER) ||
  128         acpi_timer_dev)
  129         return_VOID;
  130 
  131     if ((dev = BUS_ADD_CHILD(parent, 2, "acpi_timer", 0)) == NULL) {
  132         device_printf(parent, "could not add acpi_timer0\n");
  133         return_VOID;
  134     }
  135     acpi_timer_dev = dev;
  136 
  137     switch (AcpiGbl_FADT.XPmTimerBlock.SpaceId) {
  138     case ACPI_ADR_SPACE_SYSTEM_MEMORY:
  139         rtype = SYS_RES_MEMORY;
  140         break;
  141     case ACPI_ADR_SPACE_SYSTEM_IO:
  142         rtype = SYS_RES_IOPORT;
  143         break;
  144     default:
  145         return_VOID;
  146     }
  147     rid = 0;
  148     rlen = AcpiGbl_FADT.PmTimerLength;
  149     rstart = AcpiGbl_FADT.XPmTimerBlock.Address;
  150     if (bus_set_resource(dev, rtype, rid, rstart, rlen))
  151         device_printf(dev, "couldn't set resource (%s 0x%lx+0x%lx)\n",
  152             (rtype == SYS_RES_IOPORT) ? "port" : "mem", rstart, rlen);
  153     return_VOID;
  154 }
  155 
  156 static int
  157 acpi_timer_probe(device_t dev)
  158 {
  159     char desc[40];
  160     int i, j, rid, rtype;
  161 
  162     ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
  163 
  164     if (dev != acpi_timer_dev)
  165         return (ENXIO);
  166 
  167     switch (AcpiGbl_FADT.XPmTimerBlock.SpaceId) {
  168     case ACPI_ADR_SPACE_SYSTEM_MEMORY:
  169         rtype = SYS_RES_MEMORY;
  170         break;
  171     case ACPI_ADR_SPACE_SYSTEM_IO:
  172         rtype = SYS_RES_IOPORT;
  173         break;
  174     default:
  175         return (ENXIO);
  176     }
  177     rid = 0;
  178     acpi_timer_reg = bus_alloc_resource_any(dev, rtype, &rid, RF_ACTIVE);
  179     if (acpi_timer_reg == NULL) {
  180         device_printf(dev, "couldn't allocate resource (%s 0x%lx)\n",
  181             (rtype == SYS_RES_IOPORT) ? "port" : "mem",
  182             (u_long)AcpiGbl_FADT.XPmTimerBlock.Address);
  183         return (ENXIO);
  184     }
  185     acpi_timer_bsh = rman_get_bushandle(acpi_timer_reg);
  186     acpi_timer_bst = rman_get_bustag(acpi_timer_reg);
  187     if (AcpiGbl_FADT.Flags & ACPI_FADT_32BIT_TIMER)
  188         acpi_timer_timecounter.tc_counter_mask = 0xffffffff;
  189     else
  190         acpi_timer_timecounter.tc_counter_mask = 0x00ffffff;
  191     acpi_timer_timecounter.tc_frequency = acpi_timer_frequency;
  192     acpi_timer_timecounter.tc_flags = TC_FLAGS_SUSPEND_SAFE;
  193     if (testenv("debug.acpi.timer_test"))
  194         acpi_timer_boot_test();
  195 
  196     /*
  197      * If all tests of the counter succeed, use the ACPI-fast method.  If
  198      * at least one failed, default to using the safe routine, which reads
  199      * the timer multiple times to get a consistent value before returning.
  200      */
  201     j = 0;
  202     if (bootverbose)
  203         printf("ACPI timer:");
  204     for (i = 0; i < 10; i++)
  205         j += acpi_timer_test();
  206     if (bootverbose)
  207         printf(" -> %d\n", j);
  208     if (j == 10) {
  209         acpi_timer_timecounter.tc_name = "ACPI-fast";
  210         acpi_timer_timecounter.tc_get_timecount = acpi_timer_get_timecount;
  211         acpi_timer_timecounter.tc_quality = 900;
  212     } else {
  213         acpi_timer_timecounter.tc_name = "ACPI-safe";
  214         acpi_timer_timecounter.tc_get_timecount = acpi_timer_get_timecount_safe;
  215         acpi_timer_timecounter.tc_quality = 850;
  216     }
  217     tc_init(&acpi_timer_timecounter);
  218 
  219     sprintf(desc, "%d-bit timer at %u.%06uMHz",
  220         (AcpiGbl_FADT.Flags & ACPI_FADT_32BIT_TIMER) != 0 ? 32 : 24,
  221         acpi_timer_frequency / 1000000, acpi_timer_frequency % 1000000);
  222     device_set_desc_copy(dev, desc);
  223 
  224     /* Release the resource, we'll allocate it again during attach. */
  225     bus_release_resource(dev, rtype, rid, acpi_timer_reg);
  226     return (0);
  227 }
  228 
  229 static int
  230 acpi_timer_attach(device_t dev)
  231 {
  232     int rid, rtype;
  233 
  234     ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
  235 
  236     switch (AcpiGbl_FADT.XPmTimerBlock.SpaceId) {
  237     case ACPI_ADR_SPACE_SYSTEM_MEMORY:
  238         rtype = SYS_RES_MEMORY;
  239         break;
  240     case ACPI_ADR_SPACE_SYSTEM_IO:
  241         rtype = SYS_RES_IOPORT;
  242         break;
  243     default:
  244         return (ENXIO);
  245     }
  246     rid = 0;
  247     acpi_timer_reg = bus_alloc_resource_any(dev, rtype, &rid, RF_ACTIVE);
  248     if (acpi_timer_reg == NULL)
  249         return (ENXIO);
  250     acpi_timer_bsh = rman_get_bushandle(acpi_timer_reg);
  251     acpi_timer_bst = rman_get_bustag(acpi_timer_reg);
  252 
  253     /* Register suspend event handler. */
  254     if (EVENTHANDLER_REGISTER(power_suspend, acpi_timer_suspend_handler,
  255         &acpi_timer_timecounter, EVENTHANDLER_PRI_LAST) == NULL)
  256         device_printf(dev, "failed to register suspend event handler\n");
  257 
  258     return (0);
  259 }
  260 
  261 static void
  262 acpi_timer_resume_handler(struct timecounter *newtc)
  263 {
  264         struct timecounter *tc;
  265 
  266         tc = timecounter;
  267         if (tc != newtc) {
  268                 if (bootverbose)
  269                         device_printf(acpi_timer_dev,
  270                             "restoring timecounter, %s -> %s\n",
  271                             tc->tc_name, newtc->tc_name);
  272                 (void)newtc->tc_get_timecount(newtc);
  273                 (void)newtc->tc_get_timecount(newtc);
  274                 timecounter = newtc;
  275         }
  276 }
  277 
  278 static void
  279 acpi_timer_suspend_handler(struct timecounter *newtc)
  280 {
  281         struct timecounter *tc;
  282 
  283         /* Deregister existing resume event handler. */
  284         if (acpi_timer_eh != NULL) {
  285                 EVENTHANDLER_DEREGISTER(power_resume, acpi_timer_eh);
  286                 acpi_timer_eh = NULL;
  287         }
  288 
  289         if ((timecounter->tc_flags & TC_FLAGS_SUSPEND_SAFE) != 0) {
  290                 /*
  291                  * If we are using a suspend safe timecounter, don't
  292                  * save/restore it across suspend/resume.
  293                  */
  294                 return;
  295         }
  296 
  297         KASSERT(newtc == &acpi_timer_timecounter,
  298             ("acpi_timer_suspend_handler: wrong timecounter"));
  299 
  300         tc = timecounter;
  301         if (tc != newtc) {
  302                 if (bootverbose)
  303                         device_printf(acpi_timer_dev,
  304                             "switching timecounter, %s -> %s\n",
  305                             tc->tc_name, newtc->tc_name);
  306                 (void)acpi_timer_read();
  307                 (void)acpi_timer_read();
  308                 timecounter = newtc;
  309                 acpi_timer_eh = EVENTHANDLER_REGISTER(power_resume,
  310                     acpi_timer_resume_handler, tc, EVENTHANDLER_PRI_LAST);
  311         }
  312 }
  313 
  314 /*
  315  * Fetch current time value from reliable hardware.
  316  */
  317 static u_int
  318 acpi_timer_get_timecount(struct timecounter *tc)
  319 {
  320     return (acpi_timer_read());
  321 }
  322 
  323 /*
  324  * Fetch current time value from hardware that may not correctly
  325  * latch the counter.  We need to read until we have three monotonic
  326  * samples and then use the middle one, otherwise we are not protected
  327  * against the fact that the bits can be wrong in two directions.  If
  328  * we only cared about monosity, two reads would be enough.
  329  */
  330 static u_int
  331 acpi_timer_get_timecount_safe(struct timecounter *tc)
  332 {
  333     u_int u1, u2, u3;
  334 
  335     u2 = acpi_timer_read();
  336     u3 = acpi_timer_read();
  337     do {
  338         u1 = u2;
  339         u2 = u3;
  340         u3 = acpi_timer_read();
  341     } while (u1 > u2 || u2 > u3);
  342 
  343     return (u2);
  344 }
  345 
  346 /*
  347  * Timecounter freqency adjustment interface.
  348  */ 
  349 static int
  350 acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS)
  351 {
  352     int error;
  353     u_int freq;
  354  
  355     if (acpi_timer_timecounter.tc_frequency == 0)
  356         return (EOPNOTSUPP);
  357     freq = acpi_timer_frequency;
  358     error = sysctl_handle_int(oidp, &freq, 0, req);
  359     if (error == 0 && req->newptr != NULL) {
  360         acpi_timer_frequency = freq;
  361         acpi_timer_timecounter.tc_frequency = acpi_timer_frequency;
  362     }
  363 
  364     return (error);
  365 }
  366  
  367 SYSCTL_PROC(_machdep, OID_AUTO, acpi_timer_freq, CTLTYPE_INT | CTLFLAG_RW,
  368     0, sizeof(u_int), acpi_timer_sysctl_freq, "I", "ACPI timer frequency");
  369 
  370 /*
  371  * Some ACPI timers are known or believed to suffer from implementation
  372  * problems which can lead to erroneous values being read.  This function
  373  * tests for consistent results from the timer and returns 1 if it believes
  374  * the timer is consistent, otherwise it returns 0.
  375  *
  376  * It appears the cause is that the counter is not latched to the PCI bus
  377  * clock when read:
  378  *
  379  * ] 20. ACPI Timer Errata
  380  * ]
  381  * ]   Problem: The power management timer may return improper result when
  382  * ]   read. Although the timer value settles properly after incrementing,
  383  * ]   while incrementing there is a 3nS window every 69.8nS where the
  384  * ]   timer value is indeterminate (a 4.2% chance that the data will be
  385  * ]   incorrect when read). As a result, the ACPI free running count up
  386  * ]   timer specification is violated due to erroneous reads.  Implication:
  387  * ]   System hangs due to the "inaccuracy" of the timer when used by
  388  * ]   software for time critical events and delays.
  389  * ]
  390  * ] Workaround: Read the register twice and compare.
  391  * ] Status: This will not be fixed in the PIIX4 or PIIX4E, it is fixed
  392  * ] in the PIIX4M.
  393  */
  394 #define N 2000
  395 static int
  396 acpi_timer_test()
  397 {
  398     uint32_t last, this;
  399     int delta, max, max2, min, n;
  400     register_t s;
  401 
  402     min = INT32_MAX;
  403     max = max2 = 0;
  404 
  405     /* Test the timer with interrupts disabled to get accurate results. */
  406     s = intr_disable();
  407     last = acpi_timer_read();
  408     for (n = 0; n < N; n++) {
  409         this = acpi_timer_read();
  410         delta = acpi_TimerDelta(this, last);
  411         if (delta > max) {
  412             max2 = max;
  413             max = delta;
  414         } else if (delta > max2)
  415             max2 = delta;
  416         if (delta < min)
  417             min = delta;
  418         last = this;
  419     }
  420     intr_restore(s);
  421 
  422     delta = max2 - min;
  423     if ((max - min > 8 || delta > 3) && vm_guest == VM_GUEST_NO)
  424         n = 0;
  425     else if (min < 0 || max == 0 || max2 == 0)
  426         n = 0;
  427     else
  428         n = 1;
  429     if (bootverbose)
  430         printf(" %d/%d", n, delta);
  431 
  432     return (n);
  433 }
  434 #undef N
  435 
  436 /*
  437  * Test harness for verifying ACPI timer behaviour.
  438  * Boot with debug.acpi.timer_test set to invoke this.
  439  */
  440 static void
  441 acpi_timer_boot_test(void)
  442 {
  443     uint32_t u1, u2, u3;
  444 
  445     u1 = acpi_timer_read();
  446     u2 = acpi_timer_read();
  447     u3 = acpi_timer_read();
  448 
  449     device_printf(acpi_timer_dev, "timer test in progress, reboot to quit.\n");
  450     for (;;) {
  451         /*
  452          * The failure case is where u3 > u1, but u2 does not fall between
  453          * the two, ie. it contains garbage.
  454          */
  455         if (u3 > u1) {
  456             if (u2 < u1 || u2 > u3)
  457                 device_printf(acpi_timer_dev,
  458                               "timer is not monotonic: 0x%08x,0x%08x,0x%08x\n",
  459                               u1, u2, u3);
  460         }
  461         u1 = u2;
  462         u2 = u3;
  463         u3 = acpi_timer_read();
  464     }
  465 }

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