x86: optimise x86's do_page_fault (C entry point for the page fault path)
[linux-2.6.git] / arch / ia64 / sn / kernel / sn2 / timer.c
index deb9baf..cf67fc5 100644 (file)
 #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>
+#include <asm/timex.h>
 
 #include <asm/sn/leds.h>
 #include <asm/sn/shub_mmr.h>
 
 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 cycle_t read_sn2(void)
+{
+       return (cycle_t)readq(RTC_COUNTER_ADDR);
+}
+
+static struct clocksource clocksource_sn2 = {
+        .name           = "sn2_rtc",
+        .rating         = 450,
+        .read           = read_sn2,
+        .mask           = (1LL << 55) - 1,
+        .mult           = 0,
+        .shift          = 10,
+        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 };
 
+/*
+ * sn udelay uses the RTC instead of the ITC because the ITC is not
+ * synchronized across all CPUs, and the thread may migrate to another CPU
+ * if preemption is enabled.
+ */
+static void
+ia64_sn_udelay (unsigned long usecs)
+{
+       unsigned long start = rtc_time();
+       unsigned long end = start +
+                       usecs * sn_rtc_cycles_per_second / 1000000;
+
+       while (time_before((unsigned long)rtc_time(), end))
+               cpu_relax();
+}
+
 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);
+       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;
 }