2 files changed, 39 insertions, 62 deletions

diff --git a/arch/arm/mach-pxa/generic.c b/arch/arm/mach-pxa/generic.c
index 5510f6fdce55..9d6a2c00d762 100644
--- a/arch/arm/mach-pxa/generic.c
+++ b/arch/arm/mach-pxa/generic.c
@@ -25,10 +25,6 @@
 #include <linux/pm.h>
 #include <linux/string.h>
 
-#include <linux/sched.h>
-#include <asm/cnt32_to_63.h>
-#include <asm/div64.h>
-
 #include <asm/hardware.h>
 #include <asm/irq.h>
 #include <asm/system.h>
@@ -47,64 +43,6 @@
 #include "generic.h"
 
 /*
- * This is the PXA2xx sched_clock implementation. This has a resolution
- * of at least 308ns and a maximum value that depends on the value of
- * CLOCK_TICK_RATE.
- *
- * The return value is guaranteed to be monotonic in that range as
- * long as there is always less than 582 seconds between successive
- * calls to this function.
- */
-unsigned long long sched_clock(void)
-{
-        unsigned long long v = cnt32_to_63(OSCR);
-        /* Note: top bit ov v needs cleared unless multiplier is even. */
-
-#if     CLOCK_TICK_RATE == 3686400
-        /* 1E9 / 3686400 => 78125 / 288, max value = 32025597s (370 days). */
-        /* The <<1 is used to get rid of tick.hi top bit */
-        v *= 78125<<1;
-        do_div(v, 288<<1);
-#elif   CLOCK_TICK_RATE == 3250000
-        /* 1E9 / 3250000 => 4000 / 13, max value = 709490156s (8211 days) */
-        v *= 4000;
-        do_div(v, 13);
-#elif   CLOCK_TICK_RATE == 3249600
-        /* 1E9 / 3249600 => 625000 / 2031, max value = 4541295s (52 days) */
-        v *= 625000;
-        do_div(v, 2031);
-#else
-#warning "consider fixing sched_clock for your value of CLOCK_TICK_RATE"
-        /*
-         * 96-bit math to perform tick * NSEC_PER_SEC / CLOCK_TICK_RATE for
-         * any value of CLOCK_TICK_RATE. Max value is in the 80 thousand
-         * years range and truncation to unsigned long long limits it to
-         * sched_clock's max range of ~584 years.  This is nice but with
-         * higher computation cost.
-         */
-        {
-                union {
-                        unsigned long long val;
-                        struct { unsigned long lo, hi; };
-                } x;
-                unsigned long long y;
-
-                x.val = v;
-                x.hi &= 0x7fffffff;
-                y = (unsigned long long)x.lo * NSEC_PER_SEC;
-                x.lo = y;
-                y = (y >> 32) + (unsigned long long)x.hi * NSEC_PER_SEC;
-                x.hi = do_div(y, CLOCK_TICK_RATE);
-                do_div(x.val, CLOCK_TICK_RATE);
-                x.hi += y;
-                v = x.val;
-        }
-#endif
-
-        return v;
-}
-
-/*
  * Handy function to set GPIO alternate functions
  */
 
diff --git a/arch/arm/mach-pxa/time.c b/arch/arm/mach-pxa/time.c
index 98d27e646b09..7916311547ca 100644
--- a/arch/arm/mach-pxa/time.c
+++ b/arch/arm/mach-pxa/time.c
@@ -16,11 +16,48 @@
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/clockchips.h>
+#include <linux/sched.h>
 
+#include <asm/div64.h>
+#include <asm/cnt32_to_63.h>
 #include <asm/mach/irq.h>
 #include <asm/mach/time.h>
 #include <asm/arch/pxa-regs.h>
 
+/*
+ * This is PXA's sched_clock implementation. This has a resolution
+ * of at least 308 ns and a maximum value of 208 days.
+ *
+ * The return value is guaranteed to be monotonic in that range as
+ * long as there is always less than 582 seconds between successive
+ * calls to sched_clock() which should always be the case in practice.
+ */
+
+#define OSCR2NS_SCALE_FACTOR 10
+
+static unsigned long oscr2ns_scale;
+
+static void __init set_oscr2ns_scale(unsigned long oscr_rate)
+{
+        unsigned long long v = 1000000000ULL << OSCR2NS_SCALE_FACTOR;
+        do_div(v, oscr_rate);
+        oscr2ns_scale = v;
+        /*
+         * We want an even value to automatically clear the top bit
+         * returned by cnt32_to_63() without an additional run time
+         * instruction. So if the LSB is 1 then round it up.
+         */
+        if (oscr2ns_scale & 1)
+                oscr2ns_scale++;
+}
+
+unsigned long long sched_clock(void)
+{
+        unsigned long long v = cnt32_to_63(OSCR);
+        return (v * oscr2ns_scale) >> OSCR2NS_SCALE_FACTOR;
+}
+
+
 static irqreturn_t
 pxa_ost0_interrupt(int irq, void *dev_id)
 {
@@ -152,6 +189,8 @@ static void __init pxa_timer_init(void)
         OIER = 0;
         OSSR = OSSR_M0 | OSSR_M1 | OSSR_M2 | OSSR_M3;
 
+        set_oscr2ns_scale(CLOCK_TICK_RATE);
+
         ckevt_pxa_osmr0.mult =
                 div_sc(CLOCK_TICK_RATE, NSEC_PER_SEC, ckevt_pxa_osmr0.shift);
         ckevt_pxa_osmr0.max_delta_ns =