incubator-nuttx/sched/clock/clock_gettime.c

157 lines
4.8 KiB
C

/****************************************************************************
* sched/clock/clock_gettime.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdint.h>
#include <time.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>
#include <arch/irq.h>
#include <nuttx/arch.h>
#include "clock/clock.h"
#ifdef CONFIG_CLOCK_TIMEKEEPING
# include "clock/clock_timekeeping.h"
#endif
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: clock_gettime
*
* Description:
* Clock Functions based on POSIX APIs
*
****************************************************************************/
int clock_gettime(clockid_t clock_id, struct timespec *tp)
{
struct timespec ts;
uint32_t carry;
int ret = OK;
sinfo("clock_id=%d\n", clock_id);
DEBUGASSERT(tp != NULL);
#ifdef CONFIG_CLOCK_MONOTONIC
/* CLOCK_MONOTONIC is an optional under POSIX: "If the Monotonic Clock
* option is supported, all implementations shall support a clock_id
* of CLOCK_MONOTONIC defined in <time.h>. This clock represents the
* monotonic clock for the system. For this clock, the value returned
* by clock_gettime() represents the amount of time (in seconds and
* nanoseconds) since an unspecified point in the past (for example,
* system start-up time, or the Epoch). This point does not change
* after system start-up time. The value of the CLOCK_MONOTONIC clock
* cannot be set via clock_settime(). This function shall fail if it
* is invoked with a clock_id argument of CLOCK_MONOTONIC."
*/
if (clock_id == CLOCK_MONOTONIC || clock_id == CLOCK_BOOTTIME)
{
/* The the time elapsed since the timer was initialized at power on
* reset.
*/
ret = clock_systime_timespec(tp);
}
else
#endif
/* CLOCK_REALTIME - POSIX demands this to be present. CLOCK_REALTIME
* represents the machine's best-guess as to the current wall-clock,
* time-of-day time. This means that CLOCK_REALTIME can jump forward and
* backward as the system time-of-day clock is changed.
*/
if (clock_id == CLOCK_REALTIME)
{
/* Get the elapsed time since the time-of-day was last set.
* clock_systime_timespec() provides the time since power was applied;
* the bias value corresponds to the time when the time-of-day was
* last set.
*/
#if defined(CONFIG_CLOCK_TIMEKEEPING)
ret = clock_timekeeping_get_wall_time(tp);
#else
ret = clock_systime_timespec(&ts);
if (ret == OK)
{
irqstate_t flags;
/* Add the base time to this. The base time is the time-of-day
* setting. When added to the elapsed time since the time-of-day
* was last set, this gives us the current time.
*/
flags = spin_lock_irqsave(NULL);
ts.tv_sec += (uint32_t)g_basetime.tv_sec;
ts.tv_nsec += (uint32_t)g_basetime.tv_nsec;
spin_unlock_irqrestore(NULL, flags);
/* Handle carry to seconds. */
if (ts.tv_nsec >= NSEC_PER_SEC)
{
carry = ts.tv_nsec / NSEC_PER_SEC;
ts.tv_sec += carry;
ts.tv_nsec -= (carry * NSEC_PER_SEC);
}
/* And return the result to the caller. */
tp->tv_sec = ts.tv_sec;
tp->tv_nsec = ts.tv_nsec;
}
#endif /* CONFIG_CLOCK_TIMEKEEPING */
}
else
{
ret = -EINVAL;
}
/* Check for errors and set the errno value if necessary */
if (ret < 0)
{
serr("Returning ERROR\n");
set_errno(-ret);
ret = ERROR;
}
else
{
sinfo("Returning tp=(%d,%d)\n", (int)tp->tv_sec, (int)tp->tv_nsec);
}
return ret;
}