1 files changed, 28 insertions, 3 deletions

diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 48571ac56fb7..15391c2ab013 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -52,6 +52,7 @@
 #include <linux/jiffies.h>
 #include <linux/posix-timers.h>
 #include <linux/irq.h>
+#include <linux/delay.h>
 
 #include <asm/io.h>
 #include <asm/processor.h>
@@ -109,7 +110,7 @@ static void decrementer_set_mode(enum clock_event_mode mode,
 static struct clock_event_device decrementer_clockevent = {
        .name           = "decrementer",
        .rating         = 200,
-       .shift          = 16,
+       .shift          = 0,     /* To be filled in */
        .mult           = 0,     /* To be filled in */
        .irq            = 0,
        .set_next_event = decrementer_set_next_event,
@@ -843,6 +844,22 @@ static void decrementer_set_mode(enum clock_event_mode mode,
                 decrementer_set_next_event(DECREMENTER_MAX, dev);
 }
 
+static void __init setup_clockevent_multiplier(unsigned long hz)
+{
+        u64 mult, shift = 32;
+
+        while (1) {
+                mult = div_sc(hz, NSEC_PER_SEC, shift);
+                if (mult && (mult >> 32UL) == 0UL)
+                        break;
+
+                shift--;
+        }
+
+        decrementer_clockevent.shift = shift;
+        decrementer_clockevent.mult = mult;
+}
+
 static void register_decrementer_clockevent(int cpu)
 {
         struct clock_event_device *dec = &per_cpu(decrementers, cpu).event;
@@ -860,8 +877,7 @@ static void __init init_decrementer_clockevent(void)
 {
         int cpu = smp_processor_id();
 
-        decrementer_clockevent.mult = div_sc(ppc_tb_freq, NSEC_PER_SEC,
-                                             decrementer_clockevent.shift);
+        setup_clockevent_multiplier(ppc_tb_freq);
         decrementer_clockevent.max_delta_ns =
                 clockevent_delta2ns(DECREMENTER_MAX, &decrementer_clockevent);
         decrementer_clockevent.min_delta_ns =
@@ -1128,6 +1144,15 @@ void div128_by_32(u64 dividend_high, u64 dividend_low,
 
 }
 
+/* We don't need to calibrate delay, we use the CPU timebase for that */
+void calibrate_delay(void)
+{
+        /* Some generic code (such as spinlock debug) use loops_per_jiffy
+         * as the number of __delay(1) in a jiffy, so make it so
+         */
+        loops_per_jiffy = tb_ticks_per_jiffy;
+}
+
 static int __init rtc_init(void)
 {
         struct platform_device *pdev;