diff options
Diffstat (limited to 'src/cpu')
| -rw-r--r-- | src/cpu/x86/Kconfig | 7 | ||||
| -rw-r--r-- | src/cpu/x86/lapic/apic_timer.c | 43 |
2 files changed, 50 insertions, 0 deletions
diff --git a/src/cpu/x86/Kconfig b/src/cpu/x86/Kconfig index 4c5176b693..6b70ae7c6c 100644 --- a/src/cpu/x86/Kconfig +++ b/src/cpu/x86/Kconfig @@ -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 diff --git a/src/cpu/x86/lapic/apic_timer.c b/src/cpu/x86/lapic/apic_timer.c index b60da27256..749fef03c4 100644 --- a/src/cpu/x86/lapic/apic_timer.c +++ b/src/cpu/x86/lapic/apic_timer.c @@ -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 |