Fix several bugs where 32-bit timers and wraparound were not properly

supported.  Symptoms of this bug included unnecessary use of ACPI-safe
and a dmesg that has deltas of about 2^24:

    ACPI timer looks BAD  min = 2, max = 16777206, width = 16777204
    ACPI timer looks BAD  min = 2, max = 7, width = 5
    ACPI timer looks GOOD min = 4, max = 5, width = 1
    ACPI timer looks BAD  min = 2, max = 16777206, width = 16777204
    ACPI timer looks BAD  min = 2, max = 7, width = 5
    ACPI timer looks BAD  min = 2, max = 16777210, width = 16777208
    ACPI timer looks BAD  min = 4, max = 16777189, width = 16777185
    ACPI timer looks GOOD min = 4, max = 5, width = 1
    ACPI timer looks BAD  min = 2, max = 7, width = 5
    ACPI timer looks BAD  min = 4, max = 16777189, width = 16777185

To fix this:
* Use a 32 bit timecounter mask when the timer is 32 bits.
* In test_counter(), use the acpi_TimerDelta function which handles 24/32
  bit timers and wraparound.

Miscellaneous fixes:
* Use C99 initializers for timecounter struct.
* Use u_int and uint32_t where appropriate instead of unsigned.
* Remove whitespace-only lines
* Remove the old PIIX4 PCI workaround.  The timecounter testing code has
  been in use for long enough to prove it's functional.
This commit is contained in:
Nate Lawson 2004-04-21 00:48:16 +00:00
parent 47d91ba394
commit 75988358a2

View File

@ -31,11 +31,7 @@
#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>
@ -63,12 +59,12 @@ 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 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 uint32_t read_counter(void);
static u_int read_counter(void);
static int test_counter(void);
static device_method_t acpi_timer_methods[] = {
@ -90,20 +86,20 @@ 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,
0,
0xffffff,
0,
"ACPI",
1000
.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 uint32_t
static u_int
read_counter()
{
bus_space_handle_t bsh;
bus_space_tag_t bst;
u_int32_t tv;
uint32_t tv;
bsh = rman_get_bushandle(acpi_timer_reg);
bst = rman_get_bustag(acpi_timer_reg);
@ -117,7 +113,7 @@ read_counter()
static int
test_counter()
{
u_int last, this;
uint32_t last, this;
int min, max, n, delta;
min = 10000000;
@ -125,7 +121,7 @@ test_counter()
last = read_counter();
for (n = 0; n < N; n++) {
this = read_counter();
delta = (this - last) & 0xffffff;
delta = acpi_TimerDelta(this, last);
if (delta > max)
max = delta;
else if (delta < min)
@ -164,7 +160,7 @@ acpi_timer_identify(driver_t *driver, device_t parent)
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;
@ -183,12 +179,16 @@ acpi_timer_identify(driver_t *driver, device_t parent)
rtype == SYS_RES_IOPORT ? "port" : "mem", rstart);
return_VOID;
}
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();
acpi_timer_timecounter.tc_frequency = acpi_timer_frequency;
j = 0;
for(i = 0; i < 10; i++)
for (i = 0; i < 10; i++)
j += test_counter();
if (j == 10) {
acpi_timer_timecounter.tc_name = "ACPI-fast";
@ -224,7 +224,7 @@ acpi_timer_attach(device_t dev)
/*
* Fetch current time value from reliable hardware.
*/
static unsigned
static u_int
acpi_timer_get_timecount(struct timecounter *tc)
{
return (read_counter());
@ -234,10 +234,10 @@ acpi_timer_get_timecount(struct timecounter *tc)
* Fetch current time value from hardware that may not correctly
* latch the counter.
*/
static unsigned
static u_int
acpi_timer_get_timecount_safe(struct timecounter *tc)
{
unsigned u1, u2, u3;
u_int u1, u2, u3;
u2 = read_counter();
u3 = read_counter();
@ -281,12 +281,12 @@ SYSCTL_PROC(_machdep, OID_AUTO, acpi_timer_freq, CTLTYPE_INT | CTLFLAG_RW,
static void
acpi_timer_test(void)
{
u_int32_t u1, u2, u3;
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 (;;) {
/*
@ -304,87 +304,3 @@ acpi_timer_test(void)
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