1 files changed, 48 insertions, 0 deletions

diff --git a/arch/x86/include/asm/mach_timer.h b/arch/x86/include/asm/mach_timer.h
new file mode 100644
index 000000000000..853728519ae9
--- /dev/null
+++ b/arch/x86/include/asm/mach_timer.h
@@ -0,0 +1,48 @@
+/*
+ *  Machine specific calibrate_tsc() for generic.
+ *  Split out from timer_tsc.c by Osamu Tomita <tomita@cinet.co.jp>
+ */
+/* ------ Calibrate the TSC ------- 
+ * Return 2^32 * (1 / (TSC clocks per usec)) for do_fast_gettimeoffset().
+ * Too much 64-bit arithmetic here to do this cleanly in C, and for
+ * accuracy's sake we want to keep the overhead on the CTC speaker (channel 2)
+ * output busy loop as low as possible. We avoid reading the CTC registers
+ * directly because of the awkward 8-bit access mechanism of the 82C54
+ * device.
+ */
+#ifndef _ASM_X86_MACH_DEFAULT_MACH_TIMER_H
+#define _ASM_X86_MACH_DEFAULT_MACH_TIMER_H
+
+#define CALIBRATE_TIME_MSEC 30 /* 30 msecs */
+#define CALIBRATE_LATCH \
+        ((CLOCK_TICK_RATE * CALIBRATE_TIME_MSEC + 1000/2)/1000)
+
+static inline void mach_prepare_counter(void)
+{
+       /* Set the Gate high, disable speaker */
+        outb((inb(0x61) & ~0x02) | 0x01, 0x61);
+
+        /*
+         * Now let's take care of CTC channel 2
+         *
+         * Set the Gate high, program CTC channel 2 for mode 0,
+         * (interrupt on terminal count mode), binary count,
+         * load 5 * LATCH count, (LSB and MSB) to begin countdown.
+         *
+         * Some devices need a delay here.
+         */
+        outb(0xb0, 0x43);                       /* binary, mode 0, LSB/MSB, Ch 2 */
+        outb_p(CALIBRATE_LATCH & 0xff, 0x42);   /* LSB of count */
+        outb_p(CALIBRATE_LATCH >> 8, 0x42);       /* MSB of count */
+}
+
+static inline void mach_countup(unsigned long *count_p)
+{
+        unsigned long count = 0;
+        do {
+                count++;
+        } while ((inb_p(0x61) & 0x20) == 0);
+        *count_p = count;
+}
+
+#endif /* _ASM_X86_MACH_DEFAULT_MACH_TIMER_H */