xnu-4570.1.46.tar.gz

[apple/xnu.git] / osfmk / i386 / tsc.c

diff --git a/osfmk/i386/tsc.c b/osfmk/i386/tsc.c
index c186ffc089330d15938f9133b1d4a74d4d7d86eb..c776541db5f04723619740476c7b7e5e4e59ce5a 100644 (file)
--- a/osfmk/i386/tsc.c
+++ b/osfmk/i386/tsc.c
@@ -165,6 +165,37 @@ tsc_init(void)
        }
 
        switch (cpuid_cpufamily()) {
+       case CPUFAMILY_INTEL_KABYLAKE:
+       case CPUFAMILY_INTEL_SKYLAKE: {
+               /*
+                * SkyLake and later has an Always Running Timer (ART) providing
+                * the reference frequency. CPUID leaf 0x15 determines the
+                * rationship between this and the TSC frequency expressed as
+                *   -  multiplier (numerator, N), and 
+                *   -  divisor (denominator, M).
+                * So that TSC = ART * N / M.
+                */
+               cpuid_tsc_leaf_t *tsc_leafp = &cpuid_info()->cpuid_tsc_leaf;
+               uint64_t         N = (uint64_t) tsc_leafp->numerator;
+               uint64_t         M = (uint64_t) tsc_leafp->denominator;
+               uint64_t         refFreq;
+
+               refFreq = EFI_get_frequency("ARTFrequency");
+               if (refFreq == 0)
+                       refFreq = BASE_ART_CLOCK_SOURCE;
+
+               assert(N != 0);
+               assert(M != 1);
+               tscFreq = refFreq * N / M;
+               busFreq = tscFreq;              /* bus is APIC frequency */
+
+               kprintf(" ART: Frequency = %6d.%06dMHz, N/M = %lld/%llu\n",
+                       (uint32_t)(refFreq / Mega),
+                       (uint32_t)(refFreq % Mega), 
+                       N, M);
+
+               break;
+           }
        default: {
                uint64_t msr_flex_ratio;
                uint64_t msr_platform_info;
@@ -192,7 +223,6 @@ tsc_init(void)
 
                break;
             }
-       case CPUFAMILY_INTEL_MEROM:
        case CPUFAMILY_INTEL_PENRYN: {
                uint64_t        prfsts;