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Implement a "proper" timecounter hung off the ACPI timer device.

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This code is based on the mp_clock code by phk.  It attempts to
detect the PIIX4 (see comments for details) and use a workaround
for its problems.

This code is experimental, and could use some testing and review by a
timekeeping enthusiast.
This commit is contained in:
Mike Smith 2001-07-21 04:08:42 +00:00
parent da3b867e37
commit 787fa5b805
1 changed files with 210 additions and 23 deletions
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233
sys/dev/acpica/acpi_timer.c
View File

@ -1,5 +1,5 @@
/*-
* Copyright (c) 2000 Michael Smith
* Copyright (c) 2000, 2001 Michael Smith
* Copyright (c) 2000 BSDi
* All rights reserved.
*
@ -26,15 +26,36 @@
*
* $FreeBSD$
*/
/*
* ----------------------------------------------------------------------------
* "THE BEER-WARE LICENSE" (Revision 42):
* <phk@FreeBSD.ORG> wrote this file. As long as you retain this notice you
* can do whatever you want with this stuff. If we meet some day, and you think
* this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp
* ----------------------------------------------------------------------------
*/
#include "opt_acpi.h"
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/timetc.h>
#include <machine/bus_pio.h>
#include <machine/bus.h>
#include <machine/resource.h>
#include <sys/rman.h>
#include "acpi.h"
#include <dev/acpica/acpivar.h>
#include <acpica/acpivar.h>
#include <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
@ -42,18 +63,49 @@
#define _COMPONENT ACPI_SYSTEM
MODULE_NAME("TIMER")
#define ACPITIMER_MAGIC 0x524d4954 /* "TIMR" */
static device_t acpi_timer_dev;
struct resource *acpi_timer_reg;
#define TIMER_READ bus_space_read_4(rman_get_bustag(acpi_timer_reg), \
rman_get_bushandle(acpi_timer_reg), \
0)
static int acpi_timer_flags;
/*
* ] 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.
*
* 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.
*/
#define TFLAG_NEED_PIIX_WAR (1 << 0)
struct acpi_timer_softc {
device_t tm_dev;
};
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 int acpi_timer_pci_probe(device_t dev);
static unsigned acpi_timer_get_timecount(struct timecounter *tc);
static int acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS);
static void acpi_timer_test(void);
/*
* Driver hung off ACPI.
*/
static device_method_t acpi_timer_methods[] = {
/* Device interface */
DEVMETHOD(device_identify, acpi_timer_identify),
DEVMETHOD(device_probe, acpi_timer_probe),
DEVMETHOD(device_attach, acpi_timer_attach),
@ -64,17 +116,53 @@ static device_method_t acpi_timer_methods[] = {
static driver_t acpi_timer_driver = {
"acpi_timer",
acpi_timer_methods,
sizeof(struct acpi_timer_softc),
0,
};
devclass_t acpi_timer_devclass;
DRIVER_MODULE(acpi_timer, acpi, acpi_timer_driver, acpi_timer_devclass, 0, 0);
/*
* Chipset workaround driver hung off PCI.
*/
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);
/*
* Timecounter.
*/
static struct timecounter acpi_timer_timecounter = {
acpi_timer_get_timecount,
0,
0xffffff,
0,
"ACPI"
};
SYSCTL_OPAQUE(_debug, OID_AUTO, acpi_timecounter, CTLFLAG_RD,
&acpi_timer_timecounter, sizeof(acpi_timer_timecounter), "S,timecounter", "");
/*
* 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];
device_t dev;
char desc[40];
int rid;
FUNCTION_TRACE(__func__);
@ -88,10 +176,18 @@ acpi_timer_identify(driver_t *driver, device_t parent)
device_printf(parent, "could not add acpi_timer0\n");
return_VOID;
}
if (acpi_set_magic(dev, ACPITIMER_MAGIC)) {
device_printf(dev, "could not set magic\n");
acpi_timer_dev = dev;
rid = 0;
bus_set_resource(dev, SYS_RES_IOPORT, rid, AcpiGbl_FADT->V1_PmTmrBlk, sizeof(u_int32_t));
if ((acpi_timer_reg = bus_alloc_resource(dev, SYS_RES_IOPORT, &rid, 0, ~0, 1, RF_ACTIVE)) == NULL) {
device_printf(dev, "couldn't allocate I/O resource (port 0x%x)\n", AcpiGbl_FADT->V1_PmTmrBlk);
return_VOID;
}
if (getenv("debug.acpi.timer_test") != NULL)
acpi_timer_test();
acpi_timer_timecounter.tc_frequency = acpi_timer_frequency;
tc_init(&acpi_timer_timecounter);
sprintf(desc, "%d-bit timer at 3.579545MHz", AcpiGbl_FADT->TmrValExt ? 32 : 24);
device_set_desc_copy(dev, desc);
@ -102,7 +198,7 @@ acpi_timer_identify(driver_t *driver, device_t parent)
static int
acpi_timer_probe(device_t dev)
{
if (acpi_get_magic(dev) == ACPITIMER_MAGIC)
if (dev == acpi_timer_dev)
return(0);
return(ENXIO);
}
@ -110,12 +206,103 @@ acpi_timer_probe(device_t dev)
static int
acpi_timer_attach(device_t dev)
{
struct acpi_timer_softc *sc;
FUNCTION_TRACE(__func__);
sc = device_get_softc(dev);
sc->tm_dev = dev;
return_VALUE(0);
return(0);
}
/*
* Look at PCI devices as they go past, and if we detect a PIIX4, set
* the PIIX_WAR flag.
*
* XXX do we know that other timecounters work? Interesting question.
*/
static int
acpi_timer_pci_probe(device_t dev)
{
if ((pci_get_vendor(dev) == 0x8086) &&
(pci_get_device(dev) == 0x7113)) {
acpi_timer_flags |= TFLAG_NEED_PIIX_WAR;
device_printf(acpi_timer_dev, "enabling PIIX4 timer workaround\n");
}
return(ENXIO); /* we never match anything */
}
/*
* Fetch current time value from hardware.
*
* XXX This is currently written to be "correct", not
* "fast". Optimisation is strongly indicated.
*/
static unsigned
acpi_timer_get_timecount(struct timecounter *tc)
{
unsigned u1, u2, u3;
if (acpi_timer_flags & TFLAG_NEED_PIIX_WAR) {
u2 = TIMER_READ;
u3 = TIMER_READ;
do {
u1 = u2;
u2 = u3;
u3 = TIMER_READ;
} while (u1 > u2 || u2 > u3);
return (u2);
} else {
return(TIMER_READ);
}
}
/*
* 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;
tc_update(&acpi_timer_timecounter);
}
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 = TIMER_READ;
u2 = TIMER_READ;
u3 = 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 = TIMER_READ;
}
}