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lapic: monotonic time implementation

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Implement the timer_monotonic_get() functionality based off of
the local apic timer.

Change-Id: I1aa1ff64d15a3056d6abd1372be13da682c5ee2e
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/3154
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
This commit is contained in:
Aaron Durbin
2013-04-29 17:18:49 -05:00
committed by Ronald G. Minnich
parent c46cc6f149
commit fd8291c9d4
2 changed files with 50 additions and 0 deletions
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7
src/cpu/x86/Kconfig
View File

@@ -11,6 +11,13 @@ config UDELAY_LAPIC
bool
default n
config LAPIC_MONOTONIC_TIMER
def_bool n
depends on UDELAY_LAPIC
select HAVE_MONOTONIC_TIMER
help
Expose monotonic time using the local apic.
config UDELAY_LAPIC_FIXED_FSB
int

43
src/cpu/x86/lapic/apic_timer.c
View File

@@ -19,6 +19,7 @@
*/
#include <stdint.h>
#include <console/console.h>
#include <delay.h>
#include <arch/io.h>
#include <arch/cpu.h>
@@ -106,3 +107,45 @@ void udelay(u32 usecs)
value = lapic_read(LAPIC_TMCCT);
} while((start - value) < ticks);
}
#if CONFIG_LAPIC_MONOTONIC_TIMER && !defined(__PRE_RAM__)
#include <timer.h>
static struct monotonic_counter {
int initialized;
struct mono_time time;
uint32_t last_value;
} mono_counter;
void timer_monotonic_get(struct mono_time *mt)
{
uint32_t current_tick;
uint32_t usecs_elapsed;
if (!mono_counter.initialized) {
init_timer();
/* An FSB frequency of 200Mhz provides a 20 second polling
* interval between timer_monotonic_get() calls before wrap
* around occurs. */
if (timer_fsb > 200)
printk(BIOS_WARNING,
"apic timer freq (%d) may be too fast.\n",
timer_fsb);
mono_counter.last_value = lapic_read(LAPIC_TMCCT);
mono_counter.initialized = 1;
}
current_tick = lapic_read(LAPIC_TMCCT);
/* Note that the APIC timer counts down. */
usecs_elapsed = (mono_counter.last_value - current_tick) / timer_fsb;
/* Update current time and tick values only if a full tick occurred. */
if (usecs_elapsed) {
mono_time_add_usecs(&mono_counter.time, usecs_elapsed);
mono_counter.last_value = current_tick;
}
/* Save result. */
*mt = mono_counter.time;
}
#endif