xnu-3247.1.106.tar.gz

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

diff --git a/osfmk/i386/tsc.c b/osfmk/i386/tsc.c
index ebf7f59937bd4f6e1ffe6cc769c9cc1a55fc4d37..c186ffc089330d15938f9133b1d4a74d4d7d86eb 100644 (file)
--- a/osfmk/i386/tsc.c
+++ b/osfmk/i386/tsc.c
@@ -90,14 +90,12 @@ uint64_t    tsc_at_boot = 0;
 
 #define CPU_FAMILY_PENTIUM_M   (0x6)
 
-static const char      FSB_Frequency_prop[] = "FSBFrequency";
-static const char      TSC_at_boot_prop[]   = "InitialTSC";
 /*
- * This routine extracts the bus frequency in Hz from the device tree.
+ * This routine extracts a frequency property in Hz from the device tree.
  * Also reads any initial TSC value at boot from the device tree.
  */
 static uint64_t
-EFI_FSB_frequency(void)
+EFI_get_frequency(const char *prop)
 {
        uint64_t        frequency = 0;
        DTEntry         entry;
@@ -105,34 +103,27 @@ EFI_FSB_frequency(void)
        unsigned int    size;
 
        if (DTLookupEntry(0, "/efi/platform", &entry) != kSuccess) {
-               kprintf("EFI_FSB_frequency: didn't find /efi/platform\n");
+               kprintf("EFI_get_frequency: didn't find /efi/platform\n");
                return 0;
        }
-       if (DTGetProperty(entry,FSB_Frequency_prop,&value,&size) != kSuccess) {
-               kprintf("EFI_FSB_frequency: property %s not found\n",
-                       FSB_Frequency_prop);
+       if (DTGetProperty(entry,prop,&value,&size) != kSuccess) {
+               kprintf("EFI_get_frequency: property %s not found\n", prop);
                return 0;
        }
        if (size == sizeof(uint64_t)) {
                frequency = *(uint64_t *) value;
-               kprintf("EFI_FSB_frequency: read %s value: %llu\n",
-                       FSB_Frequency_prop, frequency);
-               if (!(90*Mega < frequency && frequency < 10*Giga)) {
-                       kprintf("EFI_FSB_frequency: value out of range\n");
-                       frequency = 0;
-               }
-       } else {
-               kprintf("EFI_FSB_frequency: unexpected size %d\n", size);
+               kprintf("EFI_get_frequency: read %s value: %llu\n",
+                       prop, frequency);
        }
 
        /*
         * While we're here, see if EFI published an initial TSC value.
         */
-       if (DTGetProperty(entry,TSC_at_boot_prop,&value,&size) == kSuccess) {
+       if (DTGetProperty(entry,"InitialTSC",&value,&size) == kSuccess) {
                if (size == sizeof(uint64_t)) {
                        tsc_at_boot = *(uint64_t *) value;
-                       kprintf("EFI_FSB_frequency: read %s value: %llu\n",
-                               TSC_at_boot_prop, tsc_at_boot);
+                       kprintf("EFI_get_frequency: read InitialTSC: %llu\n",
+                               tsc_at_boot);
                }
        }
 
@@ -173,11 +164,6 @@ tsc_init(void)
                }
        }
 
-       /*
-        * Get the FSB frequency and conversion factors from EFI.
-        */
-       busFreq = EFI_FSB_frequency();
-
        switch (cpuid_cpufamily()) {
        default: {
                uint64_t msr_flex_ratio;
@@ -197,6 +183,7 @@ tsc_init(void)
                                tscGranularity = flex_ratio;
                }
 
+               busFreq = EFI_get_frequency("FSBFrequency");
                /* If EFI isn't configured correctly, use a constant 
                 * value. See 6036811.
                 */
@@ -212,6 +199,8 @@ tsc_init(void)
                prfsts = rdmsr64(IA32_PERF_STS);
                tscGranularity = (uint32_t)bitfield(prfsts, 44, 40);
                N_by_2_bus_ratio = (prfsts & bit(46)) != 0;
+
+               busFreq = EFI_get_frequency("FSBFrequency");
            }
        }
 
@@ -229,25 +218,34 @@ tsc_init(void)
                (uint32_t)(busFCvtt2n >> 32), (uint32_t)busFCvtt2n,
                (uint32_t)(busFCvtn2t >> 32), (uint32_t)busFCvtn2t);
 
-       /*
-        * Get the TSC increment.  The TSC is incremented by this
-        * on every bus tick.  Calculate the TSC conversion factors
-        * to and from nano-seconds.
-        * The tsc granularity is also called the "bus ratio". If the N/2 bit
-        * is set this indicates the bus ration is 0.5 more than this - i.e.
-        * that the true bus ratio is (2*tscGranularity + 1)/2. If we cannot
-        * determine the TSC conversion, assume it ticks at the bus frequency.
-        */
-       if (tscGranularity == 0)
+       if (tscFreq == busFreq) {
+               bus2tsc = 1;
                tscGranularity = 1;
+               tscFCvtn2t = busFCvtn2t;
+               tscFCvtt2n = busFCvtt2n;
+       } else {
+               /*
+                * Get the TSC increment.  The TSC is incremented by this
+                * on every bus tick.  Calculate the TSC conversion factors
+                * to and from nano-seconds.
+                * The tsc granularity is also called the "bus ratio".
+                * If the N/2 bit is set this indicates the bus ration is
+                * 0.5 more than this - i.e.  that the true bus ratio
+                * is (2*tscGranularity + 1)/2.
+                */
+               if (N_by_2_bus_ratio)
+                       tscFCvtt2n = busFCvtt2n * 2 / (1 + 2*tscGranularity);
+               else
+                       tscFCvtt2n = busFCvtt2n / tscGranularity;
 
-       if (N_by_2_bus_ratio)
-               tscFCvtt2n = busFCvtt2n * 2 / (1 + 2*tscGranularity);
-       else
-               tscFCvtt2n = busFCvtt2n / tscGranularity;
+               tscFreq = ((1 * Giga)  << 32) / tscFCvtt2n;
+               tscFCvtn2t = 0xFFFFFFFFFFFFFFFFULL / tscFCvtt2n;
 
-       tscFreq = ((1 * Giga)  << 32) / tscFCvtt2n;
-       tscFCvtn2t = 0xFFFFFFFFFFFFFFFFULL / tscFCvtt2n;
+               /*
+                * Calculate conversion from BUS to TSC
+                */
+               bus2tsc = tmrCvt(busFCvtt2n, tscFCvtn2t);
+       }
 
        kprintf(" TSC: Frequency = %6d.%06dMHz, "
                "cvtt2n = %08X.%08X, cvtn2t = %08X.%08X, gran = %lld%s\n",
@@ -256,11 +254,6 @@ tsc_init(void)
                (uint32_t)(tscFCvtt2n >> 32), (uint32_t)tscFCvtt2n,
                (uint32_t)(tscFCvtn2t >> 32), (uint32_t)tscFCvtn2t,
                tscGranularity, N_by_2_bus_ratio ? " (N/2)" : "");
-
-       /*
-        * Calculate conversion from BUS to TSC
-        */
-       bus2tsc = tmrCvt(busFCvtt2n, tscFCvtn2t);
 }
 
 void