i386: Allow KVM on i386 nonpae

[linux-2.6-omap-h63xx.git] / include / asm-i386 / timer.h

diff --git a/include/asm-i386/timer.h b/include/asm-i386/timer.h
index d1f7b4f575b4abe20e9a703c5ec1d16016ab2a8a..51a713e33a9ee8d590e4729657521601588a6a8b 100644 (file)
--- a/include/asm-i386/timer.h
+++ b/include/asm-i386/timer.h
@@ -7,16 +7,46 @@
 
 void setup_pit_timer(void);
 unsigned long long native_sched_clock(void);
+unsigned long native_calculate_cpu_khz(void);
 
-/* Modifiers for buggy PIT handling */
-extern int pit_latch_buggy;
 extern int timer_ack;
 extern int no_timer_check;
 extern int no_sync_cmos_clock;
 extern int recalibrate_cpu_khz(void);
 
 #ifndef CONFIG_PARAVIRT
-#define get_scheduled_cycles(val) rdtscll(val)
+#define calculate_cpu_khz() native_calculate_cpu_khz()
 #endif
 
+/* Accellerators for sched_clock()
+ * convert from cycles(64bits) => nanoseconds (64bits)
+ *  basic equation:
+ *             ns = cycles / (freq / ns_per_sec)
+ *             ns = cycles * (ns_per_sec / freq)
+ *             ns = cycles * (10^9 / (cpu_khz * 10^3))
+ *             ns = cycles * (10^6 / cpu_khz)
+ *
+ *     Then we use scaling math (suggested by george@mvista.com) to get:
+ *             ns = cycles * (10^6 * SC / cpu_khz) / SC
+ *             ns = cycles * cyc2ns_scale / SC
+ *
+ *     And since SC is a constant power of two, we can convert the div
+ *  into a shift.
+ *
+ *  We can use khz divisor instead of mhz to keep a better percision, since
+ *  cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits.
+ *  (mathieu.desnoyers@polymtl.ca)
+ *
+ *                     -johnstul@us.ibm.com "math is hard, lets go shopping!"
+ */
+extern unsigned long cyc2ns_scale __read_mostly;
+
+#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
+
+static inline unsigned long long cycles_2_ns(unsigned long long cyc)
+{
+       return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR;
+}
+
+
 #endif