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.
     *
     *      $FreeBSD: releng/5.2/sys/dev/acpica/acpi_timer.c 119529 2003-08-28 16:06:30Z njl $
     */
    #include "opt_acpi.h"
    #include <sys/param.h>
    #include <sys/bus.h>
    #include <sys/kernel.h>
    #include <sys/sysctl.h>
    #if __FreeBSD_version >= 500000
    #include <sys/timetc.h>
    #else
    #include <sys/time.h>
    #endif
    
    #include <machine/bus.h>
    #include <machine/resource.h>
    #include <sys/rman.h>
    
    #include "acpi.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_SYSTEM
    ACPI_MODULE_NAME("TIMER")
    
    static device_t acpi_timer_dev;
    struct resource *acpi_timer_reg;
    
    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 unsigned acpi_timer_get_timecount(struct timecounter *tc);
    static unsigned acpi_timer_get_timecount_safe(struct timecounter *tc);
    static int      acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS);
    static void     acpi_timer_test(void);
    
    static uint32_t read_counter(void);
    static int      test_counter(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);
    
    static struct timecounter acpi_timer_timecounter = {
            acpi_timer_get_timecount_safe,
            0,
            0xffffff,
            0,
            "ACPI",
            1000
    };
    
   static uint32_t
   read_counter()
   {
       bus_space_handle_t bsh;
       bus_space_tag_t bst;
       u_int32_t tv;
   
       bsh = rman_get_bushandle(acpi_timer_reg);
       bst = rman_get_bustag(acpi_timer_reg);
       tv = bus_space_read_4(bst, bsh, 0);
       bus_space_barrier(bst, bsh, 0, 4, BUS_SPACE_BARRIER_READ);
   
       return (tv);
   }
   
   #define N 2000
   static int
   test_counter()
   {
       u_int       last, this;
       int         min, max, n, delta;
   
       min = 10000000;
       max = 0;
       last = read_counter();
       for (n = 0; n < N; n++) {
           this = read_counter();
           delta = (this - last) & 0xffffff;
           if (delta > max)
               max = delta;
           else if (delta < min)
               min = delta;
           last = this;
       }
       if (max - min > 2)
           n = 0;
       else if (min < 0 || max == 0)
           n = 0;
       else
           n = 1;
       if (bootverbose) {
           printf("ACPI timer looks %s min = %d, max = %d, width = %d\n",
                   n ? "GOOD" : "BAD ",
                   min, max, max - min);
       }
   
       return (n);
   }
   #undef N
   
   /*
    * 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;
       char        desc[40];
       u_long      rlen, rstart;
       int         i, j, rid, rtype;
   
       ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
   
       if (acpi_disabled("timer") || AcpiGbl_FADT == NULL)
           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;
   
       rid = 0;
       rlen = AcpiGbl_FADT->PmTmLen;
       rtype = (AcpiGbl_FADT->XPmTmrBlk.AddressSpaceId)
         ? SYS_RES_IOPORT : SYS_RES_MEMORY;
       rstart = AcpiGbl_FADT->XPmTmrBlk.Address;
       bus_set_resource(dev, rtype, rid, rstart, rlen);
       acpi_timer_reg = bus_alloc_resource(dev, rtype, &rid, 0, ~0, 1, RF_ACTIVE);
       if (acpi_timer_reg == NULL) {
           device_printf(dev, "couldn't allocate I/O resource (%s 0x%lx)\n",
                         rtype == SYS_RES_IOPORT ? "port" : "mem", rstart);
           return_VOID;
       }
       if (testenv("debug.acpi.timer_test"))
           acpi_timer_test();
   
       acpi_timer_timecounter.tc_frequency = acpi_timer_frequency;
       j = 0;
       for(i = 0; i < 10; i++)
           j += test_counter();
       if (j == 10) {
           acpi_timer_timecounter.tc_name = "ACPI-fast";
           acpi_timer_timecounter.tc_get_timecount = acpi_timer_get_timecount;
       } else {
           acpi_timer_timecounter.tc_name = "ACPI-safe";
           acpi_timer_timecounter.tc_get_timecount = acpi_timer_get_timecount_safe;
       }
       tc_init(&acpi_timer_timecounter);
   
       sprintf(desc, "%d-bit timer at 3.579545MHz",
               AcpiGbl_FADT->TmrValExt ? 32 : 24);
       device_set_desc_copy(dev, desc);
   
       return_VOID;
   }
   
   static int
   acpi_timer_probe(device_t dev)
   {
       if (dev == acpi_timer_dev)
           return (0);
   
       return (ENXIO);
   }
   
   static int
   acpi_timer_attach(device_t dev)
   {
       return (0);
   }
   
   /*
    * Fetch current time value from reliable hardware.
    */
   static unsigned
   acpi_timer_get_timecount(struct timecounter *tc)
   {
       return (read_counter());
   }
   
   /*
    * Fetch current time value from hardware that may not correctly
    * latch the counter.
    */
   static unsigned
   acpi_timer_get_timecount_safe(struct timecounter *tc)
   {
       unsigned u1, u2, u3;
   
       u2 = read_counter();
       u3 = read_counter();
       do {
           u1 = u2;
           u2 = u3;
           u3 = read_counter();
       } while (u1 > u2 || u2 > u3 || u3 - u1 > 15);
   
       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, sizeof(freq), 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", "");
   
   /*
    * Test harness for verifying ACPI timer behaviour.
    * Boot with debug.acpi.timer_test set to invoke this.
    */
   static void
   acpi_timer_test(void)
   {
       u_int32_t   u1, u2, u3;
       
       u1 = read_counter();
       u2 = read_counter();
       u3 = read_counter();
       
       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 = read_counter();
       }
   }
   
   /*
    * Chipset workaround driver hung off PCI.
    *
    * Some ACPI timers are known or believed to suffer from implementation
    * problems which can lead to erroneous values being read from the timer.
    *
    * Since we can't trust unknown chipsets, we default to a timer-read
    * routine which compensates for the most common problem (as detailed
    * in the excerpt from the Intel PIIX4 datasheet below).
    *
    * When we detect a known-functional chipset, we disable the workaround
    * to improve speed.
    *
    * ] 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.
    *
    * The counter is in other words not latched to the PCI bus clock when
    * read.  Notice the workaround isn't:  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.
    */
   
   #if 0
   static int      acpi_timer_pci_probe(device_t dev);
   
   static device_method_t acpi_timer_pci_methods[] = {
       DEVMETHOD(device_probe,     acpi_timer_pci_probe),
       {0, 0}
   };
   
   static driver_t acpi_timer_pci_driver = {
       "acpi_timer_pci",
       acpi_timer_pci_methods,
       0,
   };
   
   devclass_t acpi_timer_pci_devclass;
   DRIVER_MODULE(acpi_timer_pci, pci, acpi_timer_pci_driver,
                 acpi_timer_pci_devclass, 0, 0);
   
   /*
    * Look at PCI devices going past; if we detect one we know contains
    * a functional ACPI timer device, enable the faster timecounter read
    * routine.
    */
   static int
   acpi_timer_pci_probe(device_t dev)
   {
       int vendor, device, revid;
       
       vendor = pci_get_vendor(dev);
       device = pci_get_device(dev);
       revid  = pci_get_revid(dev);
       
       /* Detect the PIIX4M and i440MX, respectively */
       if ((vendor == 0x8086 && device == 0x7113 && revid >= 0x03) ||
           (vendor == 0x8086 && device == 0x719b)) {
   
           acpi_timer_timecounter.tc_get_timecount = acpi_timer_get_timecount;
           acpi_timer_timecounter.tc_name = "ACPI-fast";
           if (bootverbose) {
               device_printf(acpi_timer_dev,"functional ACPI timer detected, "
                             "enabling fast timecount interface\n");
           }
       }
   
       /* We never match anything */
       return (ENXIO);
   }
   #endif

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