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x86/mrst: Add support for Penwell clock calibration 

Signed-off-by: Dirk Brandewie <dirk.brandewie@gmail.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Dirk Brandewie 2011-11-10 13:42:53 +00:00 committed by Ingo Molnar
parent 1ade93efd0
commit 0a9153261d
2 changed files with 34 additions and 4 deletions
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7
arch/x86/include/asm/mrst.h
View File

@ -44,6 +44,13 @@ enum mrst_timer_options {
extern enum mrst_timer_options mrst_timer_options;
/*
* Penwell uses spread spectrum clock, so the freq number is not exactly
* the same as reported by MSR based on SDM.
*/
#define PENWELL_FSB_FREQ_83SKU 83200
#define PENWELL_FSB_FREQ_100SKU 99840
#define SFI_MTMR_MAX_NUM 8
#define SFI_MRTC_MAX 8

31
arch/x86/platform/mrst/mrst.c
View File

@ -187,11 +187,34 @@ int __init sfi_parse_mrtc(struct sfi_table_header *table)
static unsigned long __init mrst_calibrate_tsc(void)
{
unsigned long flags, fast_calibrate;
if (__mrst_cpu_chip == MRST_CPU_CHIP_PENWELL) {
u32 lo, hi, ratio, fsb;
local_irq_save(flags);
fast_calibrate = apbt_quick_calibrate();
local_irq_restore(flags);
rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
pr_debug("IA32 perf status is 0x%x, 0x%0x\n", lo, hi);
ratio = (hi >> 8) & 0x1f;
pr_debug("ratio is %d\n", ratio);
if (!ratio) {
pr_err("read a zero ratio, should be incorrect!\n");
pr_err("force tsc ratio to 16 ...\n");
ratio = 16;
}
rdmsr(MSR_FSB_FREQ, lo, hi);
if ((lo & 0x7) == 0x7)
fsb = PENWELL_FSB_FREQ_83SKU;
else
fsb = PENWELL_FSB_FREQ_100SKU;
fast_calibrate = ratio * fsb;
pr_debug("read penwell tsc %lu khz\n", fast_calibrate);
lapic_timer_frequency = fsb * 1000 / HZ;
/* mark tsc clocksource as reliable */
set_cpu_cap(&boot_cpu_data, X86_FEATURE_TSC_RELIABLE);
} else {
local_irq_save(flags);
fast_calibrate = apbt_quick_calibrate();
local_irq_restore(flags);
}
if (fast_calibrate)
return fast_calibrate;