uml: clocksource support

Add clocksource support.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 20 insertions, 0 deletions

diff --git a/arch/um/kernel/time.c b/arch/um/kernel/time.c
index 01678487b999..3cb7135e5c47 100644
--- a/arch/um/kernel/time.c
+++ b/arch/um/kernel/time.c
@@ -97,6 +97,21 @@ static irqreturn_t um_timer(int irq, void *dev)
         return IRQ_HANDLED;
 }
 
+static cycle_t itimer_read(void)
+{
+        return os_nsecs();
+}
+
+static struct clocksource itimer_clocksource = {
+        .name           = "itimer",
+        .rating         = 300,
+        .read           = itimer_read,
+        .mask           = CLOCKSOURCE_MASK(64),
+        .mult           = 1,
+        .shift          = 0,
+        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
 static void __init setup_itimer(void)
 {
         int err;
@@ -111,6 +126,11 @@ static void __init setup_itimer(void)
                 clockevent_delta2ns(60 * HZ, &itimer_clockevent);
         itimer_clockevent.min_delta_ns =
                 clockevent_delta2ns(1, &itimer_clockevent);
+        err = clocksource_register(&itimer_clocksource);
+        if (err) {
+                printk(KERN_ERR "clocksource_register returned %d\n", err);
+                return;
+        }
         clockevents_register_device(&itimer_clockevent);
 }