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cpu/intel/common: Fix invalid MSR access 

Fix regression from commit ecea916

   cpu/intel/common: Extend FSB detection to cover TSC

MSR_EBC_FREQUENCY_ID (0x2c) was not defined for affected
CPU models and rdmsr() caused reset loops. Implementations
deviate from public documentation.

Change to IA32_PERF_STATUS (0x198) already used in i945/udelay.c
to detect FSB to TSC multiplier.

Change-Id: I7a91da221920a7e7bfccb98d76115b5c89e3b52e
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/35548
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
This commit is contained in:
Kyösti Mälkki 2019-09-23 22:58:46 +03:00
parent be756f18df
commit fe26be1181
1 changed files with 2 additions and 2 deletions
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4
src/cpu/intel/common/fsb.c
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@ -42,12 +42,12 @@ static int get_fsb_tsc(int *fsb, int *ratio)
case 0xe: /* Core Solo/Duo */
case 0x1c: /* Atom */
*fsb = core_fsb[rdmsr(MSR_FSB_FREQ).lo & 7];
*ratio = rdmsr(MSR_EBC_FREQUENCY_ID).lo >> 24;
*ratio = (rdmsr(IA32_PERF_STATUS).hi >> 8) & 0x1f;
break;
case 0xf: /* Core 2 or Xeon */
case 0x17: /* Enhanced Core */
*fsb = core2_fsb[rdmsr(MSR_FSB_FREQ).lo & 7];
*ratio = rdmsr(MSR_EBC_FREQUENCY_ID).lo >> 24;
*ratio = (rdmsr(IA32_PERF_STATUS).hi >> 8) & 0x1f;
break;
case 0x25: /* Nehalem BCLK fixed at 133MHz */
*fsb = 133;