From e0969aec2573872b9f528e33edd2cf3fb84c5948 Mon Sep 17 00:00:00 2001 From: Aaron Durbin Date: Wed, 10 Feb 2016 10:56:06 -0600 Subject: 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 Reviewed-on: https://review.coreboot.org/13670 Tested-by: build bot (Jenkins) Reviewed-by: Furquan Shaikh Reviewed-by: Andrey Petrov --- src/arch/x86/cpu.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'src/arch') 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 #include #include +#include #include #include #include @@ -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; } -- cgit v1.2.3