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acpi_hpet: correctly get number of timers/comparators in a timer block

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Also, account for a quirk of AMD/ATI HPET which reports number of timers
instead of id of the last timer as manadated by the specification.
Currently this has no effect on functionality but in the future we may
make actual use of the HPET timers, not only of its timecounter.

MFC after:	2 weeks
This commit is contained in:
Andriy Gapon 2010-01-27 10:17:28 +00:00
parent 89fc20cc5e
commit 9a6a6ecb3a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=203062
1 changed files with 18 additions and 3 deletions
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21
sys/dev/acpica/acpi_hpet.c
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@ -42,6 +42,9 @@ __FBSDID("$FreeBSD$");
#include <dev/acpica/acpivar.h>
#include <dev/acpica/acpi_hpet.h>
#define HPET_VENDID_AMD 0x4353
#define HPET_VENDID_INTEL 0x8086
ACPI_SERIAL_DECL(hpet, "ACPI HPET support");
static devclass_t acpi_hpet_devclass;
@ -155,9 +158,10 @@ static int
acpi_hpet_attach(device_t dev)
{
struct acpi_hpet_softc *sc;
int rid;
int rid, num_timers;
uint32_t val, val2;
uintmax_t freq;
uint16_t vendor;
ACPI_FUNCTION_TRACE((char *)(uintptr_t) __func__);
@ -194,10 +198,21 @@ acpi_hpet_attach(device_t dev)
freq = (1000000000000000LL + val / 2) / val;
if (bootverbose) {
val = bus_read_4(sc->mem_res, HPET_CAPABILITIES);
/*
* ATI/AMD violates IA-PC HPET (High Precision Event Timers)
* Specification and provides an off by one number
* of timers/comparators.
* Additionally, they use unregistered value in VENDOR_ID field.
*/
num_timers = 1 + ((val & HPET_CAP_NUM_TIM) >> 8);
vendor = val >> 16;
if (vendor == HPET_VENDID_AMD && num_timers > 0)
num_timers--;
device_printf(dev,
"vend: 0x%x rev: 0x%x num: %d hz: %jd opts:%s%s\n",
val >> 16, val & HPET_CAP_REV_ID,
(val & HPET_CAP_NUM_TIM) >> 8, freq,
vendor, val & HPET_CAP_REV_ID,
num_timers, freq,
(val & HPET_CAP_LEG_RT) ? " legacy_route" : "",
(val & HPET_CAP_COUNT_SIZE) ? " 64-bit" : "");
}