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authorIngo Molnar <mingo@elte.hu>2009-03-26 21:39:17 +0100
committerIngo Molnar <mingo@elte.hu>2009-03-27 17:28:43 +0100
commit6e15cf04860074ad032e88c306bea656bbdd0f22 (patch)
treec346383bb7563e8d66b2f4a502f875b259c34870 /arch/x86/include/asm/mach_timer.h
parentbe0ea69674ed95e1e98cb3687a241badc756d228 (diff)
parent60db56422043aaa455ac7f858ce23c273220f9d9 (diff)
Merge branch 'core/percpu' into percpu-cpumask-x86-for-linus-2
Conflicts: arch/parisc/kernel/irq.c arch/x86/include/asm/fixmap_64.h arch/x86/include/asm/setup.h kernel/irq/handle.c Semantic merge: arch/x86/include/asm/fixmap.h Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/include/asm/mach_timer.h')
-rw-r--r--arch/x86/include/asm/mach_timer.h48
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 */