1 files changed, 186 insertions, 0 deletions
diff --git a/arch/um/os-Linux/time.c b/arch/um/os-Linux/time.c
new file mode 100644
index 000000000..e9824d5dd
--- /dev/null
+++ b/arch/um/os-Linux/time.c
@@ -0,0 +1,186 @@
+/*
+ * Copyright (C) 2000 - 2007 Jeff Dike (jdike{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
+#include <stddef.h>
+#include <errno.h>
+#include <signal.h>
+#include <time.h>
+#include <sys/time.h>
+#include <kern_util.h>
+#include <os.h>
+#include "internal.h"
+
+int set_interval(void)
+{
+	int usec = UM_USEC_PER_SEC / UM_HZ;
+	struct itimerval interval = ((struct itimerval) { { 0, usec },
+							  { 0, usec } });
+
+	if (setitimer(ITIMER_VIRTUAL, &interval, NULL) == -1)
+		return -errno;
+
+	return 0;
+}
+
+int timer_one_shot(int ticks)
+{
+	unsigned long usec = ticks * UM_USEC_PER_SEC / UM_HZ;
+	unsigned long sec = usec / UM_USEC_PER_SEC;
+	struct itimerval interval;
+
+	usec %= UM_USEC_PER_SEC;
+	interval = ((struct itimerval) { { 0, 0 }, { sec, usec } });
+
+	if (setitimer(ITIMER_VIRTUAL, &interval, NULL) == -1)
+		return -errno;
+
+	return 0;
+}
+
+/**
+ * timeval_to_ns - Convert timeval to nanoseconds
+ * @ts:		pointer to the timeval variable to be converted
+ *
+ * Returns the scalar nanosecond representation of the timeval
+ * parameter.
+ *
+ * Ripped from linux/time.h because it's a kernel header, and thus
+ * unusable from here.
+ */
+static inline long long timeval_to_ns(const struct timeval *tv)
+{
+	return ((long long) tv->tv_sec * UM_NSEC_PER_SEC) +
+		tv->tv_usec * UM_NSEC_PER_USEC;
+}
+
+long long disable_timer(void)
+{
+	struct itimerval time = ((struct itimerval) { { 0, 0 }, { 0, 0 } });
+	long long remain, max = UM_NSEC_PER_SEC / UM_HZ;
+
+	if (setitimer(ITIMER_VIRTUAL, &time, &time) < 0)
+		printk(UM_KERN_ERR "disable_timer - setitimer failed, "
+		       "errno = %d\n", errno);
+
+	remain = timeval_to_ns(&time.it_value);
+	if (remain > max)
+		remain = max;
+
+	return remain;
+}
+
+long long os_nsecs(void)
+{
+	struct timeval tv;
+
+	gettimeofday(&tv, NULL);
+	return timeval_to_ns(&tv);
+}
+
+#ifdef UML_CONFIG_NO_HZ_COMMON
+static int after_sleep_interval(struct timespec *ts)
+{
+	return 0;
+}
+
+static void deliver_alarm(void)
+{
+	alarm_handler(SIGVTALRM, NULL, NULL);
+}
+
+static unsigned long long sleep_time(unsigned long long nsecs)
+{
+	return nsecs;
+}
+
+#else
+unsigned long long last_tick;
+unsigned long long skew;
+
+static void deliver_alarm(void)
+{
+	unsigned long long this_tick = os_nsecs();
+	int one_tick = UM_NSEC_PER_SEC / UM_HZ;
+
+	/* Protection against the host's time going backwards */
+	if ((last_tick != 0) && (this_tick < last_tick))
+		this_tick = last_tick;
+
+	if (last_tick == 0)
+		last_tick = this_tick - one_tick;
+
+	skew += this_tick - last_tick;
+
+	while (skew >= one_tick) {
+		alarm_handler(SIGVTALRM, NULL, NULL);
+		skew -= one_tick;
+	}
+
+	last_tick = this_tick;
+}
+
+static unsigned long long sleep_time(unsigned long long nsecs)
+{
+	return nsecs > skew ? nsecs - skew : 0;
+}
+
+static inline long long timespec_to_us(const struct timespec *ts)
+{
+	return ((long long) ts->tv_sec * UM_USEC_PER_SEC) +
+		ts->tv_nsec / UM_NSEC_PER_USEC;
+}
+
+static int after_sleep_interval(struct timespec *ts)
+{
+	int usec = UM_USEC_PER_SEC / UM_HZ;
+	long long start_usecs = timespec_to_us(ts);
+	struct timeval tv;
+	struct itimerval interval;
+
+	/*
+	 * It seems that rounding can increase the value returned from
+	 * setitimer to larger than the one passed in.  Over time,
+	 * this will cause the remaining time to be greater than the
+	 * tick interval.  If this happens, then just reduce the first
+	 * tick to the interval value.
+	 */
+	if (start_usecs > usec)
+		start_usecs = usec;
+
+	start_usecs -= skew / UM_NSEC_PER_USEC;
+	if (start_usecs < 0)
+		start_usecs = 0;
+
+	tv = ((struct timeval) { .tv_sec  = start_usecs / UM_USEC_PER_SEC,
+				 .tv_usec = start_usecs % UM_USEC_PER_SEC });
+	interval = ((struct itimerval) { { 0, usec }, tv });
+
+	if (setitimer(ITIMER_VIRTUAL, &interval, NULL) == -1)
+		return -errno;
+
+	return 0;
+}
+#endif
+
+void idle_sleep(unsigned long long nsecs)
+{
+	struct timespec ts;
+
+	/*
+	 * nsecs can come in as zero, in which case, this starts a
+	 * busy loop.  To prevent this, reset nsecs to the tick
+	 * interval if it is zero.
+	 */
+	if (nsecs == 0)
+		nsecs = UM_NSEC_PER_SEC / UM_HZ;
+
+	nsecs = sleep_time(nsecs);
+	ts = ((struct timespec) { .tv_sec	= nsecs / UM_NSEC_PER_SEC,
+				  .tv_nsec	= nsecs % UM_NSEC_PER_SEC });
+
+	if (nanosleep(&ts, &ts) == 0)
+		deliver_alarm();
+	after_sleep_interval(&ts);
+}