New patch to review for coreboot: a5b82a2 baytrail: fix tsc rate

[Aaron Durbin]

Aaron Durbin ([e-mail]) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/4883

-gerrit

commit a5b82a28d659b04e8da0709d5f256af537c92343
Author: Aaron Durbin 
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 
    Reviewed-on: https://chromium-review.googlesource.com/172771
    Reviewed-by: Shawn Nematbakhsh 
---
 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)