[MIPS] time: Helpers to compute clocksource/event shift and mult values.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/time.c

@@ -171,25 +171,48 @@ struct clocksource clocksource_mips = {
 	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
 };
 
-static void __init init_mips_clocksource(void)
+void __init clocksource_set_clock(struct clocksource *cs, unsigned int clock)
 {
 	u64 temp;
 	u32 shift;
 
-	if (!mips_hpt_frequency || clocksource_mips.read == null_hpt_read)
-		return;
+	/* Find a shift value */
+	for (shift = 32; shift > 0; shift--) {
+		temp = (u64) NSEC_PER_SEC << shift;
+		do_div(temp, clock);
+		if ((temp >> 32) == 0)
+			break;
+	}
+	cs->shift = shift;
+	cs->mult = (u32) temp;
+}
+
+void __cpuinit clockevent_set_clock(struct clock_event_device *cd,
+	unsigned int clock)
+{
+	u64 temp;
+	u32 shift;
 
-	/* Calclate a somewhat reasonable rating value */
-	clocksource_mips.rating = 200 + mips_hpt_frequency / 10000000;
 	/* Find a shift value */
 	for (shift = 32; shift > 0; shift--) {
 		temp = (u64) NSEC_PER_SEC << shift;
-		do_div(temp, mips_hpt_frequency);
+		do_div(temp, clock);
 		if ((temp >> 32) == 0)
 			break;
 	}
-	clocksource_mips.shift = shift;
-	clocksource_mips.mult = (u32)temp;
+	cd->shift = shift;
+	cd->mult = (u32) temp;
+}
+
+static void __init init_mips_clocksource(void)
+{
+	if (!mips_hpt_frequency || clocksource_mips.read == null_hpt_read)
+		return;
+
+	/* Calclate a somewhat reasonable rating value */
+	clocksource_mips.rating = 200 + mips_hpt_frequency / 10000000;
+
+	clocksource_set_clock(&clocksource_mips, mips_hpt_frequency);
 
 	clocksource_register(&clocksource_mips);
 }

include/asm-mips/time.h

@@ -21,6 +21,7 @@
 #include <linux/ptrace.h>
 #include <linux/rtc.h>
 #include <linux/spinlock.h>
+#include <linux/clockchips.h>
 #include <linux/clocksource.h>
 
 extern spinlock_t rtc_lock;
@@ -83,4 +84,8 @@ static inline void mips_clockevent_init(void)
 }
 #endif
 
+extern void clocksource_set_clock(struct clocksource *cs, unsigned int clock);
+extern void clockevent_set_clock(struct clock_event_device *cd,
+		unsigned int clock);
+
 #endif /* _ASM_TIME_H */