xref: /freebsd/sys/dev/acpica/acpi_timer.c (revision af807c0f339beac8648be9eb3db1641d114c42bf)

/*-
 * 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.
 *
 *	$FreeBSD$
 */
#include "opt_acpi.h"
#include <sys/param.h>
#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/timetc.h>

#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_TIMER
ACPI_MODULE_NAME("TIMER")

static device_t			acpi_timer_dev;
static struct resource		*acpi_timer_reg;
static bus_space_handle_t	timer_bsh;
static bus_space_tag_t		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_test(void);

static u_int	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);
MODULE_DEPEND(acpi_timer, acpi, 1, 1, 1);

static struct timecounter acpi_timer_timecounter = {
	.tc_get_timecount =	acpi_timer_get_timecount_safe,
	.tc_poll_pps =		0,
	.tc_counter_mask =	0,
	.tc_frequency =		0,
	.tc_name =		"ACPI",
	.tc_quality =		1000
};

static u_int
read_counter()
{
    uint32_t tv;

    tv = bus_space_read_4(timer_bst, timer_bsh, 0);
    bus_space_barrier(timer_bst, timer_bsh, 0, 4, BUS_SPACE_BARRIER_READ);
    return (tv);
}

/*
 * 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_any(dev, rtype, &rid, 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;
    }
    timer_bsh = rman_get_bushandle(acpi_timer_reg);
    timer_bst = rman_get_bustag(acpi_timer_reg);
    if (AcpiGbl_FADT->TmrValExt != 0)
	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_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;
    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 u_int
acpi_timer_get_timecount(struct timecounter *tc)
{
    return (read_counter());
}

/*
 * 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 = 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", "");

/*
 * 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
test_counter()
{
    uint32_t	last, this;
    int		min, max, n, delta;

    min = 10000000;
    max = 0;
    last = read_counter();
    for (n = 0; n < N; n++) {
	this = read_counter();
	delta = acpi_TimerDelta(this, last);
	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

/*
 * Test harness for verifying ACPI timer behaviour.
 * Boot with debug.acpi.timer_test set to invoke this.
 */
static void
acpi_timer_test(void)
{
    uint32_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();
    }
}