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baytrail: fix tsc rate

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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>
This commit is contained in:
Aaron Durbin 2013-10-11 00:44:06 -05:00 • committed by chrome-internal-fetch
commit cb03ba6992
2 changed files with 11 additions and 2 deletions
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1
src/soc/intel/baytrail/baytrail/msr.h
View file

@ -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

12
src/soc/intel/baytrail/tsc_freq.c
View file

@ -27,13 +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)