1 files changed, 49 insertions, 0 deletions
diff --git a/include/asm-i386/tsc.h b/include/asm-i386/tsc.h
new file mode 100644
index 00000000000000..97b828ce31e0b8
--- /dev/null
+++ b/include/asm-i386/tsc.h
@@ -0,0 +1,49 @@
+/*
+ * linux/include/asm-i386/tsc.h
+ *
+ * i386 TSC related functions
+ */
+#ifndef _ASM_i386_TSC_H
+#define _ASM_i386_TSC_H
+
+#include <linux/config.h>
+#include <asm/processor.h>
+
+/*
+ * Standard way to access the cycle counter on i586+ CPUs.
+ * Currently only used on SMP.
+ *
+ * If you really have a SMP machine with i486 chips or older,
+ * compile for that, and this will just always return zero.
+ * That's ok, it just means that the nicer scheduling heuristics
+ * won't work for you.
+ *
+ * We only use the low 32 bits, and we'd simply better make sure
+ * that we reschedule before that wraps. Scheduling at least every
+ * four billion cycles just basically sounds like a good idea,
+ * regardless of how fast the machine is.
+ */
+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;
+}
+
+extern void tsc_init(void);
+extern void mark_tsc_unstable(void);
+
+#endif