Aaron Durbin (adurbin@google.com) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/4883
-gerrit
commit 612677146fae6eb6d7fe1a86513f02ea1324b212 Author: Aaron Durbin adurbin@chromium.org Date: Fri Oct 11 00:44:06 2013 -0500
baytrail: fix tsc rate
Despite some references to a fixed bclk in some of the docs the bclk is variable per sku. Therefore, perform the calculation according to the BSEL_CR_OVERCLOCK_CONTROL msr which provides the bclk for the cpu cores in Bay Trail.
BUG=chrome-os-partner:23166 BRANCH=None TEST=Built and booted B3. correctly says: clocks_per_usec: 2133
Change-Id: I55da45d42e7672fdb3b821c8aed7340a6f73dd08 Signed-off-by: Aaron Durbin adurbin@chromium.org Reviewed-on: https://chromium-review.googlesource.com/172771 Reviewed-by: Shawn Nematbakhsh shawnn@chromium.org --- src/soc/intel/baytrail/baytrail/msr.h | 1 + src/soc/intel/baytrail/tsc_freq.c | 13 ++++++++++--- 2 files changed, 11 insertions(+), 3 deletions(-)
diff --git a/src/soc/intel/baytrail/baytrail/msr.h b/src/soc/intel/baytrail/baytrail/msr.h index 7f3b3b2..5094f96 100644 --- a/src/soc/intel/baytrail/baytrail/msr.h +++ b/src/soc/intel/baytrail/baytrail/msr.h @@ -21,6 +21,7 @@ #define _BAYTRAIL_MSR_H_
#define MSR_IA32_PLATFORM_ID 0x17 +#define MSR_BSEL_CR_OVERCLOCK_CONTROL 0xcd #define MSR_PLATFORM_INFO 0xce #define MSR_IA32_PERF_CTL 0x199 #define MSR_IA32_MISC_ENABLES 0x1a0 diff --git a/src/soc/intel/baytrail/tsc_freq.c b/src/soc/intel/baytrail/tsc_freq.c index 0cf7273..3b662fe 100644 --- a/src/soc/intel/baytrail/tsc_freq.c +++ b/src/soc/intel/baytrail/tsc_freq.c @@ -27,14 +27,21 @@ #include <baytrail/romstage.h> #endif
- -#define BCLK 100 /* 100 MHz */ unsigned long tsc_freq_mhz(void) { msr_t platform_info; + msr_t clk_info; + unsigned long bclk_khz;
platform_info = rdmsr(MSR_PLATFORM_INFO); - return BCLK * ((platform_info.lo >> 8) & 0xff); + clk_info = rdmsr(MSR_BSEL_CR_OVERCLOCK_CONTROL); + switch (clk_info.lo & 0x3) { + case 0: bclk_khz = 83333; break; + case 1: bclk_khz = 100000; break; + case 2: bclk_khz = 133333; break; + case 3: bclk_khz = 116666; break; + } + return (bclk_khz * ((platform_info.lo >> 8) & 0xff)) / 1000; }
void set_max_freq(void)