freebsd-skq/sys/dev/acpica/acpi_timer.c
jkim db83c1dd70 Decrease ACPI-fast timecounter quality to 900 and increase HPET timecounter
quality to 950.  HPET on modern platforms usually have better resolution and
lower latency than ACPI timer.  Effectively this changes default timecounter
hardware from ACPI-fast to HPET by default when both are available.

Discussed with:	avg
2011-05-23 20:12:36 +00:00

402 lines
11 KiB
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("$FreeBSD$");
#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();
}
}