1 files changed, 80 insertions, 0 deletions

diff --git a/include/asm-x86/tsc.h b/include/asm-x86/tsc.h
new file mode 100644
index 000000000000..6baab30dc2c8
--- /dev/null
+++ b/include/asm-x86/tsc.h
@@ -0,0 +1,80 @@
+/*
+ * x86 TSC related functions
+ */
+#ifndef _ASM_X86_TSC_H
+#define _ASM_X86_TSC_H
+
+#include <asm/processor.h>
+
+#define NS_SCALE        10 /* 2^10, carefully chosen */
+#define US_SCALE        32 /* 2^32, arbitralrily chosen */
+
+/*
+ * Standard way to access the cycle counter.
+ */
+typedef unsigned long long cycles_t;
+
+extern unsigned int cpu_khz;
+extern unsigned int tsc_khz;
+
+static inline cycles_t get_cycles(void)
+{
+        unsigned long long ret = 0;
+
+#ifndef CONFIG_X86_TSC
+        if (!cpu_has_tsc)
+                return 0;
+#endif
+
+#if defined(CONFIG_X86_GENERIC) || defined(CONFIG_X86_TSC)
+        rdtscll(ret);
+#endif
+        return ret;
+}
+
+/* Like get_cycles, but make sure the CPU is synchronized. */
+static __always_inline cycles_t get_cycles_sync(void)
+{
+        unsigned long long ret;
+        unsigned eax, edx;
+
+        /*
+         * Use RDTSCP if possible; it is guaranteed to be synchronous
+         * and doesn't cause a VMEXIT on Hypervisors
+         */
+        alternative_io(ASM_NOP3, ".byte 0x0f,0x01,0xf9", X86_FEATURE_RDTSCP,
+                       ASM_OUTPUT2("=a" (eax), "=d" (edx)),
+                       "a" (0U), "d" (0U) : "ecx", "memory");
+        ret = (((unsigned long long)edx) << 32) | ((unsigned long long)eax);
+        if (ret)
+                return ret;
+
+        /*
+         * Don't do an additional sync on CPUs where we know
+         * RDTSC is already synchronous:
+         */
+        alternative_io("cpuid", ASM_NOP2, X86_FEATURE_SYNC_RDTSC,
+                          "=a" (eax), "0" (1) : "ebx","ecx","edx","memory");
+        rdtscll(ret);
+
+        return ret;
+}
+
+extern void tsc_init(void);
+extern void mark_tsc_unstable(char *reason);
+extern int unsynchronized_tsc(void);
+extern void init_tsc_clocksource(void);
+int check_tsc_unstable(void);
+
+/*
+ * Boot-time check whether the TSCs are synchronized across
+ * all CPUs/cores:
+ */
+extern void check_tsc_sync_source(int cpu);
+extern void check_tsc_sync_target(void);
+
+#ifdef CONFIG_X86_64
+extern void tsc_calibrate(void);
+#endif
+
+#endif