[IA64] Convert to generic timekeeping/clocksource

This is a merge of Peter Keilty's initial patch (which was
revived by Bob Picco) for this with Hidetoshi Seto's fixes
and scaling improvements.

Acked-by: Bob Picco <bob.picco@hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 21 insertions, 8 deletions

diff --git a/arch/ia64/sn/kernel/sn2/timer.c b/arch/ia64/sn/kernel/sn2/timer.c
index 56a88b6df4b4..19e25d2b64fc 100644
--- a/arch/ia64/sn/kernel/sn2/timer.c
+++ b/arch/ia64/sn/kernel/sn2/timer.c
@@ -11,6 +11,7 @@
 #include <linux/sched.h>
 #include <linux/time.h>
 #include <linux/interrupt.h>
+#include <linux/clocksource.h>
 
 #include <asm/hw_irq.h>
 #include <asm/system.h>
@@ -22,11 +23,21 @@
 
 extern unsigned long sn_rtc_cycles_per_second;
 
-static struct time_interpolator sn2_interpolator = {
-        .drift = -1,
-        .shift = 10,
-        .mask = (1LL << 55) - 1,
-        .source = TIME_SOURCE_MMIO64
+static void __iomem *sn2_mc;
+
+static cycle_t read_sn2(void)
+{
+        return (cycle_t)readq(sn2_mc);
+}
+
+static struct clocksource clocksource_sn2 = {
+        .name           = "sn2_rtc",
+        .rating         = 300,
+        .read           = read_sn2,
+        .mask           = (1LL << 55) - 1,
+        .mult           = 0,
+        .shift          = 10,
+        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 };
 
 /*
@@ -47,9 +58,11 @@ ia64_sn_udelay (unsigned long usecs)
 
 void __init sn_timer_init(void)
 {
-        sn2_interpolator.frequency = sn_rtc_cycles_per_second;
-        sn2_interpolator.addr = RTC_COUNTER_ADDR;
-        register_time_interpolator(&sn2_interpolator);
+        sn2_mc = RTC_COUNTER_ADDR;
+        clocksource_sn2.fsys_mmio = RTC_COUNTER_ADDR;
+        clocksource_sn2.mult = clocksource_hz2mult(sn_rtc_cycles_per_second,
+                                                        clocksource_sn2.shift);
+        clocksource_register(&clocksource_sn2);
 
         ia64_udelay = &ia64_sn_udelay;
 }