1 /* 2 * Copyright (C) 2000 - 2007 Jeff Dike (jdike{addtoit,linux.intel}.com) 3 * Licensed under the GPL 4 */ 5 6 #include <stddef.h> 7 #include <errno.h> 8 #include <signal.h> 9 #include <time.h> 10 #include <sys/time.h> 11 #include "kern_constants.h" 12 #include "os.h" 13 #include "user.h" 14 15 int set_interval(void) 16 { 17 int usec = UM_USEC_PER_SEC / UM_HZ; 18 struct itimerval interval = ((struct itimerval) { { 0, usec }, 19 { 0, usec } }); 20 21 if (setitimer(ITIMER_VIRTUAL, &interval, NULL) == -1) 22 return -errno; 23 24 return 0; 25 } 26 27 int timer_one_shot(int ticks) 28 { 29 unsigned long usec = ticks * UM_USEC_PER_SEC / UM_HZ; 30 unsigned long sec = usec / UM_USEC_PER_SEC; 31 struct itimerval interval; 32 33 usec %= UM_USEC_PER_SEC; 34 interval = ((struct itimerval) { { 0, 0 }, { sec, usec } }); 35 36 if (setitimer(ITIMER_VIRTUAL, &interval, NULL) == -1) 37 return -errno; 38 39 return 0; 40 } 41 42 /** 43 * timeval_to_ns - Convert timeval to nanoseconds 44 * @ts: pointer to the timeval variable to be converted 45 * 46 * Returns the scalar nanosecond representation of the timeval 47 * parameter. 48 * 49 * Ripped from linux/time.h because it's a kernel header, and thus 50 * unusable from here. 51 */ 52 static inline long long timeval_to_ns(const struct timeval *tv) 53 { 54 return ((long long) tv->tv_sec * UM_NSEC_PER_SEC) + 55 tv->tv_usec * UM_NSEC_PER_USEC; 56 } 57 58 long long disable_timer(void) 59 { 60 struct itimerval time = ((struct itimerval) { { 0, 0 }, { 0, 0 } }); 61 62 if (setitimer(ITIMER_VIRTUAL, &time, &time) < 0) 63 printk(UM_KERN_ERR "disable_timer - setitimer failed, " 64 "errno = %d\n", errno); 65 66 return timeval_to_ns(&time.it_value); 67 } 68 69 long long os_nsecs(void) 70 { 71 struct timeval tv; 72 73 gettimeofday(&tv, NULL); 74 return timeval_to_ns(&tv); 75 } 76 77 #ifdef UML_CONFIG_NO_HZ 78 static int after_sleep_interval(struct timespec *ts) 79 { 80 return 0; 81 } 82 #else 83 static inline long long timespec_to_us(const struct timespec *ts) 84 { 85 return ((long long) ts->tv_sec * UM_USEC_PER_SEC) + 86 ts->tv_nsec / UM_NSEC_PER_USEC; 87 } 88 89 static int after_sleep_interval(struct timespec *ts) 90 { 91 int usec = UM_USEC_PER_SEC / UM_HZ; 92 long long start_usecs = timespec_to_us(ts); 93 struct timeval tv; 94 struct itimerval interval; 95 96 /* 97 * It seems that rounding can increase the value returned from 98 * setitimer to larger than the one passed in. Over time, 99 * this will cause the remaining time to be greater than the 100 * tick interval. If this happens, then just reduce the first 101 * tick to the interval value. 102 */ 103 if (start_usecs > usec) 104 start_usecs = usec; 105 tv = ((struct timeval) { .tv_sec = start_usecs / UM_USEC_PER_SEC, 106 .tv_usec = start_usecs % UM_USEC_PER_SEC }); 107 interval = ((struct itimerval) { { 0, usec }, tv }); 108 109 if (setitimer(ITIMER_VIRTUAL, &interval, NULL) == -1) 110 return -errno; 111 112 return 0; 113 } 114 #endif 115 116 extern void alarm_handler(int sig, struct sigcontext *sc); 117 118 void idle_sleep(unsigned long long nsecs) 119 { 120 struct timespec ts; 121 122 /* 123 * nsecs can come in as zero, in which case, this starts a 124 * busy loop. To prevent this, reset nsecs to the tick 125 * interval if it is zero. 126 */ 127 if (nsecs == 0) 128 nsecs = UM_NSEC_PER_SEC / UM_HZ; 129 ts = ((struct timespec) { .tv_sec = nsecs / UM_NSEC_PER_SEC, 130 .tv_nsec = nsecs % UM_NSEC_PER_SEC }); 131 132 if (nanosleep(&ts, &ts) == 0) 133 alarm_handler(SIGVTALRM, NULL); 134 after_sleep_interval(&ts); 135 } 136