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authorAaron Durbin <adurbin@chromium.org>2013-04-29 17:18:49 -0500
committerRonald G. Minnich <rminnich@gmail.com>2013-05-01 07:15:17 +0200
commitfd8291c9d438917e334f4211fb1142b6a7bb7e32 (patch)
tree296eae0dce43b0e4c895c90552c271f5141d7fc5
parentc46cc6f149c42653344d6e9f3656a4212fc46cef (diff)
lapic: monotonic time implementation
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>
-rw-r--r--src/cpu/x86/Kconfig7
-rw-r--r--src/cpu/x86/lapic/apic_timer.c43
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