summaryrefslogtreecommitdiff
path: root/src/arch
diff options
context:
space:
mode:
authorAaron Durbin <adurbin@chromium.org>2016-02-10 10:56:06 -0600
committerMartin Roth <martinroth@google.com>2016-02-19 19:50:10 +0100
commite0969aec2573872b9f528e33edd2cf3fb84c5948 (patch)
tree25c7b837e62b40d6261ac9a58a190dc321e736a4 /src/arch
parentf6ada1c30755f3de22942996bfcf6490a9b7b6e4 (diff)
downloadcoreboot-e0969aec2573872b9f528e33edd2cf3fb84c5948.tar.xz
x86: add coreboot table entry for TSC info
The 8254 (Programmable Interrupt Timer) is becoming optional on x86 platforms -- either from saving power or not including it at all. To allow a payload to still use a TSC without doing calibration provide the TSC frequency information in the coreboot tables. That data is provided by code/logic already employed by platform. If tsc_freq_mhz() returns 0 or CONFIG_TSC_CONSTANT_RATE is not selected the coreboot table record isn't created. BUG=chrome-os-partner:50214 BRANCH=glados TEST=With all subsequent patches confirmed TSC is picked up in libpayload. Change-Id: Iaeadb85c2648587debcf55f4fa5351d0c287e971 Signed-off-by: Aaron Durbin <adurbin@chromium.org> Reviewed-on: https://review.coreboot.org/13670 Tested-by: build bot (Jenkins) Reviewed-by: Furquan Shaikh <furquan@google.com> Reviewed-by: Andrey Petrov <andrey.petrov@intel.com>
Diffstat (limited to 'src/arch')
-rw-r--r--src/arch/x86/cpu.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/src/arch/x86/cpu.c b/src/arch/x86/cpu.c
index 5afae8b486..cba105a5db 100644
--- a/src/arch/x86/cpu.c
+++ b/src/arch/x86/cpu.c
@@ -19,6 +19,7 @@
#include <cpu/x86/mtrr.h>
#include <cpu/x86/msr.h>
#include <cpu/x86/lapic.h>
+#include <cpu/x86/tsc.h>
#include <arch/cpu.h>
#include <device/path.h>
#include <device/device.h>
@@ -291,4 +292,21 @@ void cpu_initialize(unsigned int index)
void lb_arch_add_records(struct lb_header *header)
{
+ uint32_t freq_khz;
+ struct lb_tsc_info *tsc_info;
+
+ /* Don't advertise a TSC rate unless it's constant. */
+ if (!IS_ENABLED(CONFIG_TSC_CONSTANT_RATE))
+ return;
+
+ freq_khz = tsc_freq_mhz() * 1000;
+
+ /* No use exposing a TSC frequency that is zero. */
+ if (freq_khz == 0)
+ return;
+
+ tsc_info = (void *)lb_new_record(header);
+ tsc_info->tag = LB_TAG_TSC_INFO;
+ tsc_info->size = sizeof(*tsc_info);
+ tsc_info->freq_khz = freq_khz;
}