// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk})
 * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
 * Copyright (C) 2012-2014 Cisco Systems
 * Copyright (C) 2000 - 2007 Jeff Dike (jdike{addtoit,linux.intel}.com)
 */

#include <stddef.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include <time.h>
#include <sys/time.h>
#include <kern_util.h>
#include <os.h>
#include <string.h>

static timer_t event_high_res_timer = 0;

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;
}

static inline long long timespec_to_ns(const struct timespec *ts)
{
	return ((long long) ts->tv_sec * UM_NSEC_PER_SEC) + ts->tv_nsec;
}

long long os_persistent_clock_emulation(void)
{
	struct timespec realtime_tp;

	clock_gettime(CLOCK_REALTIME, &realtime_tp);
	return timespec_to_ns(&realtime_tp);
}

/**
 * os_timer_create() - create an new posix (interval) timer
 */
int os_timer_create(void)
{
	timer_t *t = &event_high_res_timer;

	if (timer_create(CLOCK_MONOTONIC, NULL, t) == -1)
		return -1;

	return 0;
}

int os_timer_set_interval(unsigned long long nsecs)
{
	struct itimerspec its;

	its.it_value.tv_sec = nsecs / UM_NSEC_PER_SEC;
	its.it_value.tv_nsec = nsecs % UM_NSEC_PER_SEC;

	its.it_interval.tv_sec = nsecs / UM_NSEC_PER_SEC;
	its.it_interval.tv_nsec = nsecs % UM_NSEC_PER_SEC;

	if (timer_settime(event_high_res_timer, 0, &its, NULL) == -1)
		return -errno;

	return 0;
}

int os_timer_one_shot(unsigned long long nsecs)
{
	struct itimerspec its = {
		.it_value.tv_sec = nsecs / UM_NSEC_PER_SEC,
		.it_value.tv_nsec = nsecs % UM_NSEC_PER_SEC,

		.it_interval.tv_sec = 0,
		.it_interval.tv_nsec = 0, // we cheat here
	};

	timer_settime(event_high_res_timer, 0, &its, NULL);
	return 0;
}

/**
 * os_timer_disable() - disable the posix (interval) timer
 */
void os_timer_disable(void)
{
	struct itimerspec its;

	memset(&its, 0, sizeof(struct itimerspec));
	timer_settime(event_high_res_timer, 0, &its, NULL);
}

long long os_nsecs(void)
{
	struct timespec ts;

	clock_gettime(CLOCK_MONOTONIC,&ts);
	return timespec_to_ns(&ts);
}

/**
 * os_idle_sleep() - sleep until interrupted
 */
void os_idle_sleep(void)
{
	struct itimerspec its;
	sigset_t set, old;

	/* block SIGALRM while we analyze the timer state */
	sigemptyset(&set);
	sigaddset(&set, SIGALRM);
	sigprocmask(SIG_BLOCK, &set, &old);

	/* check the timer, and if it'll fire then wait for it */
	timer_gettime(event_high_res_timer, &its);
	if (its.it_value.tv_sec || its.it_value.tv_nsec)
		sigsuspend(&old);
	/* either way, restore the signal mask */
	sigprocmask(SIG_UNBLOCK, &set, NULL);
}