From 152e5a03a130cea3009685cbf7eb0ea354d9fd1c Mon Sep 17 00:00:00 2001 From: Aaron Durbin Date: Wed, 10 Feb 2016 11:01:49 -0600 Subject: libpayload: honor TSC information under CONFIG_LP_TIMER_RDTSC When CONFIG_LP_TIMER_RDTSC is enabled honor the TSC information exported in the coreboot tables as the cpu_khz frequency. That allows get_cpu_speed() not to be called which currently relies on the 8254 PIT. As certain x86 platforms allow that device to be optional or turned off for power saving reasons, allow a path where get_cpu_speed() is no longer called. Additionally, this approach also allows the libpayload to not duplicate logic that already exists in coreboot. BUG=chrome-os-partner:50214 BRANCH=glados TEST=Confirmed in payload TSC frequency is honored instead of using get_cpu_speed(). Change-Id: Ib8993afdfb49065d43de705d6dbbdb9174b6f2c4 Signed-off-by: Aaron Durbin Reviewed-on: https://review.coreboot.org/13671 Tested-by: build bot (Jenkins) Reviewed-by: Martin Roth Reviewed-by: Andrey Petrov --- payloads/libpayload/libc/coreboot.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'payloads/libpayload/libc') diff --git a/payloads/libpayload/libc/coreboot.c b/payloads/libpayload/libc/coreboot.c index 3e248e19c3..3abd610be2 100644 --- a/payloads/libpayload/libc/coreboot.c +++ b/payloads/libpayload/libc/coreboot.c @@ -231,6 +231,19 @@ static void cb_parse_boot_media_params(unsigned char *ptr, info->boot_media_size = bmp->boot_media_size; } +#if IS_ENABLED(CONFIG_LP_TIMER_RDTSC) +static void cb_parse_tsc_info(void *ptr, struct sysinfo_t *info) +{ + const struct cb_tsc_info *tsc_info = ptr; + + if (tsc_info->freq_khz == 0) + return; + + /* Honor the TSC frequency passed to the payload. */ + info->cpu_khz = tsc_info->freq_khz; +} +#endif + int cb_parse_header(void *addr, int len, struct sysinfo_t *info) { struct cb_header *header; @@ -386,6 +399,11 @@ int cb_parse_header(void *addr, int len, struct sysinfo_t *info) case CB_TAG_BOOT_MEDIA_PARAMS: cb_parse_boot_media_params(ptr, info); break; +#if IS_ENABLED(CONFIG_LP_TIMER_RDTSC) + case CB_TAG_TSC_INFO: + cb_parse_tsc_info(ptr, info); + break; +#endif default: cb_parse_arch_specific(rec, info); break; -- cgit v1.2.3