FreeBSD/Linux Kernel Cross Reference
sys/dev/acpica/acpi_timer.c

     /*-
      * Copyright (c) 2000, 2001 Michael Smith
      * Copyright (c) 2000 BSDi
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD: releng/9.0/sys/dev/acpica/acpi_timer.c 222222 2011-05-23 20:12:36Z jkim $");
    
    #include "opt_acpi.h"
    #include <sys/param.h>
    #include <sys/bus.h>
    #include <sys/kernel.h>
    #include <sys/module.h>
    #include <sys/sysctl.h>
    #include <sys/timetc.h>
    
    #include <machine/bus.h>
    #include <machine/resource.h>
    #include <sys/rman.h>
    
    #include <contrib/dev/acpica/include/acpi.h>
    #include <contrib/dev/acpica/include/accommon.h>
    
    #include <dev/acpica/acpivar.h>
    #include <dev/pci/pcivar.h>
    
    /*
     * A timecounter based on the free-running ACPI timer.
     *
     * Based on the i386-only mp_clock.c by <phk@FreeBSD.ORG>.
     */
    
    /* Hooks for the ACPI CA debugging infrastructure */
    #define _COMPONENT      ACPI_TIMER
    ACPI_MODULE_NAME("TIMER")
    
    static device_t                 acpi_timer_dev;
    static struct resource          *acpi_timer_reg;
    static bus_space_handle_t       acpi_timer_bsh;
    static bus_space_tag_t          acpi_timer_bst;
    
    static u_int    acpi_timer_frequency = 14318182 / 4;
    
    static void     acpi_timer_identify(driver_t *driver, device_t parent);
    static int      acpi_timer_probe(device_t dev);
    static int      acpi_timer_attach(device_t dev);
    static u_int    acpi_timer_get_timecount(struct timecounter *tc);
    static u_int    acpi_timer_get_timecount_safe(struct timecounter *tc);
    static int      acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS);
    static void     acpi_timer_boot_test(void);
    
    static int      acpi_timer_test(void);
    
    static device_method_t acpi_timer_methods[] = {
        DEVMETHOD(device_identify,  acpi_timer_identify),
        DEVMETHOD(device_probe,     acpi_timer_probe),
        DEVMETHOD(device_attach,    acpi_timer_attach),
    
        {0, 0}
    };
    
    static driver_t acpi_timer_driver = {
        "acpi_timer",
        acpi_timer_methods,
        0,
    };
    
    static devclass_t acpi_timer_devclass;
    DRIVER_MODULE(acpi_timer, acpi, acpi_timer_driver, acpi_timer_devclass, 0, 0);
    MODULE_DEPEND(acpi_timer, acpi, 1, 1, 1);
    
    static struct timecounter acpi_timer_timecounter = {
            acpi_timer_get_timecount_safe,  /* get_timecount function */
            0,                              /* no poll_pps */
            0,                              /* no default counter_mask */
            0,                              /* no default frequency */
            "ACPI",                         /* name */
           -1                              /* quality (chosen later) */
   };
   
   static __inline uint32_t
   acpi_timer_read(void)
   {
   
       return (bus_space_read_4(acpi_timer_bst, acpi_timer_bsh, 0));
   }
   
   /*
    * Locate the ACPI timer using the FADT, set up and allocate the I/O resources
    * we will be using.
    */
   static void
   acpi_timer_identify(driver_t *driver, device_t parent)
   {
       device_t dev;
       u_long rlen, rstart;
       int rid, rtype;
   
       ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
   
       if (acpi_disabled("timer") || (acpi_quirks & ACPI_Q_TIMER) ||
           acpi_timer_dev)
           return_VOID;
   
       if ((dev = BUS_ADD_CHILD(parent, 0, "acpi_timer", 0)) == NULL) {
           device_printf(parent, "could not add acpi_timer0\n");
           return_VOID;
       }
       acpi_timer_dev = dev;
   
       switch (AcpiGbl_FADT.XPmTimerBlock.SpaceId) {
       case ACPI_ADR_SPACE_SYSTEM_MEMORY:
           rtype = SYS_RES_MEMORY;
           break;
       case ACPI_ADR_SPACE_SYSTEM_IO:
           rtype = SYS_RES_IOPORT;
           break;
       default:
           return_VOID;
       }
       rid = 0;
       rlen = AcpiGbl_FADT.PmTimerLength;
       rstart = AcpiGbl_FADT.XPmTimerBlock.Address;
       if (bus_set_resource(dev, rtype, rid, rstart, rlen))
           device_printf(dev, "couldn't set resource (%s 0x%lx+0x%lx)\n",
               (rtype == SYS_RES_IOPORT) ? "port" : "mem", rstart, rlen);
       return_VOID;
   }
   
   static int
   acpi_timer_probe(device_t dev)
   {
       char desc[40];
       int i, j, rid, rtype;
   
       ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
   
       if (dev != acpi_timer_dev)
           return (ENXIO);
   
       switch (AcpiGbl_FADT.XPmTimerBlock.SpaceId) {
       case ACPI_ADR_SPACE_SYSTEM_MEMORY:
           rtype = SYS_RES_MEMORY;
           break;
       case ACPI_ADR_SPACE_SYSTEM_IO:
           rtype = SYS_RES_IOPORT;
           break;
       default:
           return (ENXIO);
       }
       rid = 0;
       acpi_timer_reg = bus_alloc_resource_any(dev, rtype, &rid, RF_ACTIVE);
       if (acpi_timer_reg == NULL) {
           device_printf(dev, "couldn't allocate resource (%s 0x%lx)\n",
               (rtype == SYS_RES_IOPORT) ? "port" : "mem",
               (u_long)AcpiGbl_FADT.XPmTimerBlock.Address);
           return (ENXIO);
       }
       acpi_timer_bsh = rman_get_bushandle(acpi_timer_reg);
       acpi_timer_bst = rman_get_bustag(acpi_timer_reg);
       if (AcpiGbl_FADT.Flags & ACPI_FADT_32BIT_TIMER)
           acpi_timer_timecounter.tc_counter_mask = 0xffffffff;
       else
           acpi_timer_timecounter.tc_counter_mask = 0x00ffffff;
       acpi_timer_timecounter.tc_frequency = acpi_timer_frequency;
       if (testenv("debug.acpi.timer_test"))
           acpi_timer_boot_test();
   
       /*
        * If all tests of the counter succeed, use the ACPI-fast method.  If
        * at least one failed, default to using the safe routine, which reads
        * the timer multiple times to get a consistent value before returning.
        */
       j = 0;
       if (bootverbose)
           printf("ACPI timer:");
       for (i = 0; i < 10; i++)
           j += acpi_timer_test();
       if (bootverbose)
           printf(" -> %d\n", j);
       if (j == 10) {
           acpi_timer_timecounter.tc_name = "ACPI-fast";
           acpi_timer_timecounter.tc_get_timecount = acpi_timer_get_timecount;
           acpi_timer_timecounter.tc_quality = 900;
       } else {
           acpi_timer_timecounter.tc_name = "ACPI-safe";
           acpi_timer_timecounter.tc_get_timecount = acpi_timer_get_timecount_safe;
           acpi_timer_timecounter.tc_quality = 850;
       }
       tc_init(&acpi_timer_timecounter);
   
       sprintf(desc, "%d-bit timer at %u.%06uMHz",
           (AcpiGbl_FADT.Flags & ACPI_FADT_32BIT_TIMER) != 0 ? 32 : 24,
           acpi_timer_frequency / 1000000, acpi_timer_frequency % 1000000);
       device_set_desc_copy(dev, desc);
   
       /* Release the resource, we'll allocate it again during attach. */
       bus_release_resource(dev, rtype, rid, acpi_timer_reg);
       return (0);
   }
   
   static int
   acpi_timer_attach(device_t dev)
   {
       int rid, rtype;
   
       ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
   
       switch (AcpiGbl_FADT.XPmTimerBlock.SpaceId) {
       case ACPI_ADR_SPACE_SYSTEM_MEMORY:
           rtype = SYS_RES_MEMORY;
           break;
       case ACPI_ADR_SPACE_SYSTEM_IO:
           rtype = SYS_RES_IOPORT;
           break;
       default:
           return (ENXIO);
       }
       rid = 0;
       acpi_timer_reg = bus_alloc_resource_any(dev, rtype, &rid, RF_ACTIVE);
       if (acpi_timer_reg == NULL)
           return (ENXIO);
       acpi_timer_bsh = rman_get_bushandle(acpi_timer_reg);
       acpi_timer_bst = rman_get_bustag(acpi_timer_reg);
       return (0);
   }
   
   /*
    * Fetch current time value from reliable hardware.
    */
   static u_int
   acpi_timer_get_timecount(struct timecounter *tc)
   {
       return (acpi_timer_read());
   }
   
   /*
    * Fetch current time value from hardware that may not correctly
    * latch the counter.  We need to read until we have three monotonic
    * samples and then use the middle one, otherwise we are not protected
    * against the fact that the bits can be wrong in two directions.  If
    * we only cared about monosity, two reads would be enough.
    */
   static u_int
   acpi_timer_get_timecount_safe(struct timecounter *tc)
   {
       u_int u1, u2, u3;
   
       u2 = acpi_timer_read();
       u3 = acpi_timer_read();
       do {
           u1 = u2;
           u2 = u3;
           u3 = acpi_timer_read();
       } while (u1 > u2 || u2 > u3);
   
       return (u2);
   }
   
   /*
    * Timecounter freqency adjustment interface.
    */ 
   static int
   acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS)
   {
       int error;
       u_int freq;
    
       if (acpi_timer_timecounter.tc_frequency == 0)
           return (EOPNOTSUPP);
       freq = acpi_timer_frequency;
       error = sysctl_handle_int(oidp, &freq, 0, req);
       if (error == 0 && req->newptr != NULL) {
           acpi_timer_frequency = freq;
           acpi_timer_timecounter.tc_frequency = acpi_timer_frequency;
       }
   
       return (error);
   }
    
   SYSCTL_PROC(_machdep, OID_AUTO, acpi_timer_freq, CTLTYPE_INT | CTLFLAG_RW,
       0, sizeof(u_int), acpi_timer_sysctl_freq, "I", "ACPI timer frequency");
   
   /*
    * Some ACPI timers are known or believed to suffer from implementation
    * problems which can lead to erroneous values being read.  This function
    * tests for consistent results from the timer and returns 1 if it believes
    * the timer is consistent, otherwise it returns 0.
    *
    * It appears the cause is that the counter is not latched to the PCI bus
    * clock when read:
    *
    * ] 20. ACPI Timer Errata
    * ]
    * ]   Problem: The power management timer may return improper result when
    * ]   read. Although the timer value settles properly after incrementing,
    * ]   while incrementing there is a 3nS window every 69.8nS where the
    * ]   timer value is indeterminate (a 4.2% chance that the data will be
    * ]   incorrect when read). As a result, the ACPI free running count up
    * ]   timer specification is violated due to erroneous reads.  Implication:
    * ]   System hangs due to the "inaccuracy" of the timer when used by
    * ]   software for time critical events and delays.
    * ]
    * ] Workaround: Read the register twice and compare.
    * ] Status: This will not be fixed in the PIIX4 or PIIX4E, it is fixed
    * ] in the PIIX4M.
    */
   #define N 2000
   static int
   acpi_timer_test()
   {
       uint32_t last, this;
       int delta, max, max2, min, n;
       register_t s;
   
       min = INT32_MAX;
       max = max2 = 0;
   
       /* Test the timer with interrupts disabled to get accurate results. */
       s = intr_disable();
       last = acpi_timer_read();
       for (n = 0; n < N; n++) {
           this = acpi_timer_read();
           delta = acpi_TimerDelta(this, last);
           if (delta > max) {
               max2 = max;
               max = delta;
           } else if (delta > max2)
               max2 = delta;
           if (delta < min)
               min = delta;
           last = this;
       }
       intr_restore(s);
   
       delta = max2 - min;
       if ((max - min > 8 || delta > 3) && vm_guest == VM_GUEST_NO)
           n = 0;
       else if (min < 0 || max == 0 || max2 == 0)
           n = 0;
       else
           n = 1;
       if (bootverbose)
           printf(" %d/%d", n, delta);
   
       return (n);
   }
   #undef N
   
   /*
    * Test harness for verifying ACPI timer behaviour.
    * Boot with debug.acpi.timer_test set to invoke this.
    */
   static void
   acpi_timer_boot_test(void)
   {
       uint32_t u1, u2, u3;
   
       u1 = acpi_timer_read();
       u2 = acpi_timer_read();
       u3 = acpi_timer_read();
   
       device_printf(acpi_timer_dev, "timer test in progress, reboot to quit.\n");
       for (;;) {
           /*
            * The failure case is where u3 > u1, but u2 does not fall between
            * the two, ie. it contains garbage.
            */
           if (u3 > u1) {
               if (u2 < u1 || u2 > u3)
                   device_printf(acpi_timer_dev,
                                 "timer is not monotonic: 0x%08x,0x%08x,0x%08x\n",
                                 u1, u2, u3);
           }
           u1 = u2;
           u2 = u3;
           u3 = acpi_timer_read();
       }
   }

Cache object: 3d8b21a272b62d1152e089f4e1635514