x86/mrst: Add support for Penwell clock calibration

[mirror_ubuntu-hirsute-kernel.git] / arch / x86 / platform / mrst / mrst.c

diff --git a/arch/x86/platform/mrst/mrst.c b/arch/x86/platform/mrst/mrst.c
index 6ed7afdaf4afa5e194ea75a43c08e84d20c5d915..b7f14e5b2c661ecfbfe356a5c2529444f3139532 100644 (file)
--- a/arch/x86/platform/mrst/mrst.c
+++ b/arch/x86/platform/mrst/mrst.c
@@ -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;
-
-       local_irq_save(flags);
-       fast_calibrate = apbt_quick_calibrate();
-       local_irq_restore(flags);
-
+       if (__mrst_cpu_chip == MRST_CPU_CHIP_PENWELL) {
+               u32 lo, hi, ratio, fsb;
+
+               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;