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Reverse the logic here again with regards to "trusted" ACPI timer

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implementations.  More of them seem to be broken, so only "trust"
timers we know work.
This commit is contained in:
Mike Smith 2001-08-03 09:52:53 +00:00
parent d8c3658bb5
commit feade91944
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=81096
1 changed files with 54 additions and 30 deletions
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84
sys/dev/acpica/acpi_timer.c
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@ -67,6 +67,7 @@ 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);
@ -94,7 +95,7 @@ DRIVER_MODULE(acpi_timer, acpi, acpi_timer_driver, acpi_timer_devclass, 0, 0);
* Timecounter.
*/
static struct timecounter acpi_timer_timecounter = {
acpi_timer_get_timecount,
acpi_timer_get_timecount_safe,
0,
0xffffff,
0,
@ -144,6 +145,20 @@ acpi_timer_identify(driver_t *driver, device_t parent)
sprintf(desc, "%d-bit timer at 3.579545MHz", AcpiGbl_FADT->TmrValExt ? 32 : 24);
device_set_desc_copy(dev, desc);
#if 0
{
u_int64_t first;
first = rdtsc();
acpi_timer_get_timecount(NULL);
printf("acpi_timer_get_timecount %lld cycles\n", rdtsc() - first);
first = rdtsc();
acpi_timer_get_timecount_safe(NULL);
printf("acpi_timer_get_timecount_safe %lld cycles\n", rdtsc() - first);
}
#endif
return_VOID;
}
@ -162,7 +177,7 @@ acpi_timer_attach(device_t dev)
}
/*
* Fetch current time value from hardware.
* Fetch current time value from reliable hardware.
*/
static unsigned
acpi_timer_get_timecount(struct timecounter *tc)
@ -170,6 +185,25 @@ acpi_timer_get_timecount(struct timecounter *tc)
return(TIMER_READ);
}
/*
* 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 = TIMER_READ;
u3 = TIMER_READ;
do {
u1 = u2;
u2 = u3;
u3 = TIMER_READ;
} while (u1 > u2 || u2 > u3);
return (u2);
}
/*
* Timecounter freqency adjustment interface.
*/
@ -227,6 +261,16 @@ acpi_timer_test(void)
/*
* 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
@ -250,7 +294,6 @@ acpi_timer_test(void)
*/
static int acpi_timer_pci_probe(device_t dev);
static unsigned acpi_timer_get_timecount_piix(struct timecounter *tc);
static device_method_t acpi_timer_pci_methods[] = {
DEVMETHOD(device_probe, acpi_timer_pci_probe),
@ -267,40 +310,21 @@ 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 as they go past, and if we detect a PIIX4 older than
* the PIIX4M, use an alternate get_timecount routine.
*
* XXX do we know that other timecounters work? Perhaps we should test them?
* 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)
{
if ((pci_get_vendor(dev) == 0x8086) &&
(pci_get_device(dev) == 0x7113) &&
(pci_get_revid(dev) < 0x03)) {
acpi_timer_timecounter.tc_get_timecount = acpi_timer_get_timecount_piix;
acpi_timer_timecounter.tc_name = "ACPI-PIIX";
device_printf(acpi_timer_dev, "enabling PIIX4 timer workaround\n");
(pci_get_revid(dev) >= 0x03)) {
acpi_timer_timecounter.tc_get_timecount = acpi_timer_get_timecount;
acpi_timer_timecounter.tc_name = "ACPI-PIIX4M";
if (bootverbose)
device_printf(acpi_timer_dev, "PIIX4M or later detected, enabling ACPI timer optimisation\n");
}
return(ENXIO); /* we never match anything */
}
/*
* Read the buggy PIIX4 ACPI timer and compensate for its behaviour.
*/
static unsigned
acpi_timer_get_timecount_piix(struct timecounter *tc)
{
unsigned u1, u2, u3;
u2 = TIMER_READ;
u3 = TIMER_READ;
do {
u1 = u2;
u2 = u3;
u3 = TIMER_READ;
} while (u1 > u2 || u2 > u3);
return (u2);
}