1 files changed, 58 insertions, 1 deletions

diff --git a/arch/arm/plat-orion/time.c b/arch/arm/plat-orion/time.c
index de8a001fc3a9..715a30177f28 100644
--- a/arch/arm/plat-orion/time.c
+++ b/arch/arm/plat-orion/time.c
@@ -12,11 +12,15 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/cnt32_to_63.h>
+#include <linux/timer.h>
 #include <linux/clockchips.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
 #include <asm/mach/time.h>
 #include <mach/bridge-regs.h>
+#include <mach/hardware.h>
 
 /*
  * Number of timer ticks per jiffy.
@@ -39,6 +43,56 @@ static u32 ticks_per_jiffy;
 
 
 /*
+ * Orion's sched_clock implementation. It has a resolution of
+ * at least 7.5ns (133MHz TCLK) and a maximum value of 834 days.
+ *
+ * Because the hardware timer period is quite short (21 secs if
+ * 200MHz TCLK) and because cnt32_to_63() needs to be called at
+ * least once per half period to work properly, a kernel timer is
+ * set up to ensure this requirement is always met.
+ */
+#define TCLK2NS_SCALE_FACTOR 8
+
+static unsigned long tclk2ns_scale;
+
+unsigned long long sched_clock(void)
+{
+        unsigned long long v = cnt32_to_63(0xffffffff - readl(TIMER0_VAL));
+        return (v * tclk2ns_scale) >> TCLK2NS_SCALE_FACTOR;
+}
+
+static struct timer_list cnt32_to_63_keepwarm_timer;
+
+static void cnt32_to_63_keepwarm(unsigned long data)
+{
+        mod_timer(&cnt32_to_63_keepwarm_timer, round_jiffies(jiffies + data));
+        (void) sched_clock();
+}
+
+static void __init setup_sched_clock(unsigned long tclk)
+{
+        unsigned long long v;
+        unsigned long data;
+
+        v = NSEC_PER_SEC;
+        v <<= TCLK2NS_SCALE_FACTOR;
+        v += tclk/2;
+        do_div(v, tclk);
+        /*
+         * 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 (v & 1)
+                v++;
+        tclk2ns_scale = v;
+
+        data = (0xffffffffUL / tclk / 2 - 2) * HZ;
+        setup_timer(&cnt32_to_63_keepwarm_timer, cnt32_to_63_keepwarm, data);
+        mod_timer(&cnt32_to_63_keepwarm_timer, round_jiffies(jiffies + data));
+}
+
+/*
  * Clocksource handling.
  */
 static cycle_t orion_clksrc_read(struct clocksource *cs)
@@ -176,6 +230,10 @@ void __init orion_time_init(unsigned int irq, unsigned int tclk)
 
         ticks_per_jiffy = (tclk + HZ/2) / HZ;
 
+        /*
+         * Set scale and timer for sched_clock
+         */
+        setup_sched_clock(tclk);
 
         /*
          * Setup free-running clocksource timer (interrupts
@@ -190,7 +248,6 @@ void __init orion_time_init(unsigned int irq, unsigned int tclk)
         orion_clksrc.mult = clocksource_hz2mult(tclk, orion_clksrc.shift);
         clocksource_register(&orion_clksrc);
 
-
         /*
          * Setup clockevent timer (interrupt-driven.)
          */