[coreboot] New patch to review for coreboot: bc99d22 APIC: Fixed reading MSR_FSB_FREQ register

[Vikram Narayanan]

Vikram Narayanan ([e-mail]) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/535

-gerrit

commit bc99d2285ab900489e6737ec7e315afa812ea178
Author: Vikram Narayanan 
Date:   Sat Jan 14 14:36:51 2012 +0530

APIC: Fixed reading MSR_FSB_FREQ register

According to Intel's manual, bits 0:2 of MSR 0xCDh gives the FSB
    frequency. But the code had a right shift of 4 which will always
    give 267 MHz, as the valid bits are shifted to right.

Change-Id: I53199f212a543c642c633adf783b6490c216fb61
    Signed-off-by: Vikram Narayanan 
---
 src/cpu/x86/lapic/apic_timer.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/src/cpu/x86/lapic/apic_timer.c b/src/cpu/x86/lapic/apic_timer.c
index 826f5b6..0b56fd5 100644
--- a/src/cpu/x86/lapic/apic_timer.c
+++ b/src/cpu/x86/lapic/apic_timer.c
@@ -28,6 +28,7 @@
  */

#define FSB_CLOCK_STS 0xcd
+#define FSB_FREQ_MASK 0x07

static u32 timer_fsb = 200; // default to 200MHz

@@ -46,7 +47,7 @@ void init_timer(void)

/* Set FSB frequency to a reasonable value */
    fsb_clock_sts = rdmsr(FSB_CLOCK_STS);
-	switch ((fsb_clock_sts.lo >> 4) & 0x07) {
+	switch (fsb_clock_sts.lo & FSB_FREQ_MASK) {
    case 0: timer_fsb = 266; break;
    case 1: timer_fsb = 133; break;
    case 2: timer_fsb = 200; break;