1 files changed, 66 insertions, 0 deletions

diff --git a/arch/x86/include/asm/timer.h b/arch/x86/include/asm/timer.h
new file mode 100644
index 000000000000..d0babce4b47a
--- /dev/null
+++ b/arch/x86/include/asm/timer.h
@@ -0,0 +1,66 @@
+#ifndef ASM_X86__TIMER_H
+#define ASM_X86__TIMER_H
+#include <linux/init.h>
+#include <linux/pm.h>
+#include <linux/percpu.h>
+
+#define TICK_SIZE (tick_nsec / 1000)
+
+unsigned long long native_sched_clock(void);
+unsigned long native_calibrate_tsc(void);
+
+#ifdef CONFIG_X86_32
+extern int timer_ack;
+extern int recalibrate_cpu_khz(void);
+#endif /* CONFIG_X86_32 */
+
+extern int no_timer_check;
+
+#ifndef CONFIG_PARAVIRT
+#define calibrate_tsc() native_calibrate_tsc()
+#endif
+
+/* Accelerators 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 precision, 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!"
+ */
+
+DECLARE_PER_CPU(unsigned long, cyc2ns);
+
+#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
+
+static inline unsigned long long __cycles_2_ns(unsigned long long cyc)
+{
+        return cyc * per_cpu(cyc2ns, smp_processor_id()) >> CYC2NS_SCALE_FACTOR;
+}
+
+static inline unsigned long long cycles_2_ns(unsigned long long cyc)
+{
+        unsigned long long ns;
+        unsigned long flags;
+
+        local_irq_save(flags);
+        ns = __cycles_2_ns(cyc);
+        local_irq_restore(flags);
+
+        return ns;
+}
+
+#endif /* ASM_X86__TIMER_H */