1 files changed, 61 insertions, 0 deletions
diff --git a/arch/ia64/sn/kernel/sn2/timer.c b/arch/ia64/sn/kernel/sn2/timer.c
new file mode 100644
index 000000000..3009d9d86
--- /dev/null
+++ b/arch/ia64/sn/kernel/sn2/timer.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/arch/ia64/sn/kernel/sn2/timer.c
+ *
+ * Copyright (C) 2003 Silicon Graphics, Inc.
+ * Copyright (C) 2003 Hewlett-Packard Co
+ *	David Mosberger <davidm@hpl.hp.com>: updated for new timer-interpolation infrastructure
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/time.h>
+#include <linux/interrupt.h>
+#include <linux/clocksource.h>
+
+#include <asm/hw_irq.h>
+#include <asm/timex.h>
+
+#include <asm/sn/leds.h>
+#include <asm/sn/shub_mmr.h>
+#include <asm/sn/clksupport.h>
+
+extern unsigned long sn_rtc_cycles_per_second;
+
+static u64 read_sn2(struct clocksource *cs)
+{
+	return (u64)readq(RTC_COUNTER_ADDR);
+}
+
+static struct clocksource clocksource_sn2 = {
+        .name           = "sn2_rtc",
+        .rating         = 450,
+        .read           = read_sn2,
+        .mask           = (1LL << 55) - 1,
+        .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)
+{
+	clocksource_sn2.archdata.fsys_mmio = RTC_COUNTER_ADDR;
+	clocksource_register_hz(&clocksource_sn2, sn_rtc_cycles_per_second);
+
+	ia64_udelay = &ia64_sn_udelay;
+}