2 * Copyright (C) 2000 - 2007 Jeff Dike (jdike{addtoit,linux.intel}.com)
3 * Licensed under the GPL
11 #include "kern_constants.h"
15 int set_interval(void)
17 int usec = UM_USEC_PER_SEC / UM_HZ;
18 struct itimerval interval = ((struct itimerval) { { 0, usec },
21 if (setitimer(ITIMER_VIRTUAL, &interval, NULL) == -1)
27 int timer_one_shot(int ticks)
29 unsigned long usec = ticks * UM_USEC_PER_SEC / UM_HZ;
30 unsigned long sec = usec / UM_USEC_PER_SEC;
31 struct itimerval interval;
33 usec %= UM_USEC_PER_SEC;
34 interval = ((struct itimerval) { { 0, 0 }, { sec, usec } });
36 if (setitimer(ITIMER_VIRTUAL, &interval, NULL) == -1)
43 * timeval_to_ns - Convert timeval to nanoseconds
44 * @ts: pointer to the timeval variable to be converted
46 * Returns the scalar nanosecond representation of the timeval
49 * Ripped from linux/time.h because it's a kernel header, and thus
52 static inline long long timeval_to_ns(const struct timeval *tv)
54 return ((long long) tv->tv_sec * UM_NSEC_PER_SEC) +
55 tv->tv_usec * UM_NSEC_PER_USEC;
58 long long disable_timer(void)
60 struct itimerval time = ((struct itimerval) { { 0, 0 }, { 0, 0 } });
62 if (setitimer(ITIMER_VIRTUAL, &time, &time) < 0)
63 printk(UM_KERN_ERR "disable_timer - setitimer failed, "
64 "errno = %d\n", errno);
66 return timeval_to_ns(&time.it_value);
69 long long os_nsecs(void)
73 gettimeofday(&tv, NULL);
74 return timeval_to_ns(&tv);
77 #ifdef UML_CONFIG_NO_HZ
78 static int after_sleep_interval(struct timespec *ts)
82 static inline long long timespec_to_us(const struct timespec *ts)
84 return ((long long) ts->tv_sec * UM_USEC_PER_SEC) +
85 ts->tv_nsec / UM_NSEC_PER_USEC;
88 static int after_sleep_interval(struct timespec *ts)
90 int usec = UM_USEC_PER_SEC / UM_HZ;
91 long long start_usecs = timespec_to_us(ts);
93 struct itimerval interval;
96 * It seems that rounding can increase the value returned from
97 * setitimer to larger than the one passed in. Over time,
98 * this will cause the remaining time to be greater than the
99 * tick interval. If this happens, then just reduce the first
100 * tick to the interval value.
102 if (start_usecs > usec)
104 tv = ((struct timeval) { .tv_sec = start_usecs / UM_USEC_PER_SEC,
105 .tv_usec = start_usecs % UM_USEC_PER_SEC });
106 interval = ((struct itimerval) { { 0, usec }, tv });
108 if (setitimer(ITIMER_VIRTUAL, &interval, NULL) == -1)
115 extern void alarm_handler(int sig, struct sigcontext *sc);
117 void idle_sleep(unsigned long long nsecs)
122 * nsecs can come in as zero, in which case, this starts a
123 * busy loop. To prevent this, reset nsecs to the tick
124 * interval if it is zero.
127 nsecs = UM_NSEC_PER_SEC / UM_HZ;
128 ts = ((struct timespec) { .tv_sec = nsecs / UM_NSEC_PER_SEC,
129 .tv_nsec = nsecs % UM_NSEC_PER_SEC });
131 if (nanosleep(&ts, &ts) == 0)
132 alarm_handler(SIGVTALRM, NULL);
133 after_sleep_interval(&ts);