/****************************************************************************
* arch/sim/src/up_tickless.c
*
* Copyright (C) 2014 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Tickless OS Support.
*
* When CONFIG_SCHED_TICKLESS is enabled, all support for timer interrupts
* is suppressed and the platform specific code is expected to provide the
* following custom functions.
*
* void up_timer_initialize(void): Initializes the timer facilities. Called
* early in the intialization sequence (by up_intialize()).
* int up_timer_gettime(FAR struct timespec *ts): Returns the current
* time from the platform specific time source.
* int up_timer_cancel(void): Cancels the interval timer.
* int up_timer_start(FAR const struct timespec *ts): Start (or re-starts)
* the interval timer.
*
* The RTOS will provide the following interfaces for use by the platform-
* specific interval timer implementation:
*
* void sched_timer_expiration(void): Called by the platform-specific
* logic when the interval timer expires.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdint.h>
#include <stdbool.h>
#include <time.h>
#include <nuttx/arch.h>
#include <nuttx/clock.h>
#ifdef CONFIG_SCHED_TICKLESS
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#if defined(CONFIG_SIM_WALLTIME) || defined(CONFIG_SIM_X11FB)
# define TICK_USEC (USEC_PER_SEC / CLK_TCK)
# define TICK_SEC (TICK_USEC / USEC_PER_SEC)
# define TICK_NSEC ((TICK_USEC % NSEC_PER_USEC) * NSEC_PER_USEC)
#else
# define TICK_SEC 0
# define TICK_NSEC NSEC_PER_TICK
#endif
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
static struct timespec g_elapsed_time;
static struct timespec g_interval_delay;
static bool g_timer_active;
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: up_timer_initialize
*
* Description:
* Initializes all platform-specific timer facilities. This function is
* called early in the initialization sequence by up_intialize().
* On return, the current up-time should be available from
* up_timer_gettime() and the interval timer is ready for use (but not
* actively timing.
*
* Provided by platform-specific code and called from the architecture-
* specific logic.
*
* Input Parameters:
* None
*
* Returned Value:
* None
*
* Assumptions:
* Called early in the initialization sequence before any special
* concurrency protections are required.
*
****************************************************************************/
void up_timer_initialize(void)
{
}
/****************************************************************************
* Name: up_timer_gettime
*
* Description:
* Return the elapsed time since power-up (or, more correctly, since
* up_timer_initialize() was called). This function is functionally
* equivalent to:
*
* int clock_gettime(clockid_t clockid, FAR struct timespec *ts);
*
* when clockid is CLOCK_MONOTONIC.
*
* This function provides the basis for reporting the current time and
* also is used to eliminate error build-up from small erros in interval
* time calculations.
*
* Provided by platform-specific code and called from the RTOS base code.
*
* Input Parameters:
* ts - Provides the location in which to return the up-time.
*
* Returned Value:
* Zero (OK) is returned on success; a negated errno value is returned on
* any failure.
*
* Assumptions:
* Called from the the normal tasking context. The implementation must
* provide whatever mutual exclusion is necessary for correct operation.
* This can include disabling interrupts in order to assure atomic register
* operations.
*
****************************************************************************/
int up_timer_gettime(FAR struct timespec *ts)
{
ts->tv_sec = g_elapsed_time.tv_sec;
ts->tv_nsec = g_elapsed_time.tv_nsec;
return OK;
}
/****************************************************************************
* Name: up_timer_cancel
*
* Description:
* Cancel the interval timer and return the time remaining on the timer.
* These two steps need to be as nearly atomic as possible.
* sched_timer_expiration() will not be called unless the timer is
* restarted with up_timer_start().
*
* If, as a race condition, the timer has already expired when this
* function is called, then that pending interrupt must be cleared so
* that up_timer_start() and the remaining time of zero should be
* returned.
*
* Provided by platform-specific code and called from the RTOS base code.
*
* Input Parameters:
* ts - Location to return the remaining time. Zero should be returned
* if the timer is not active.
*
* Returned Value:
* Zero (OK) is returned on success; a negated errno value is returned on
* any failure.
*
* Assumptions:
* May be called from interrupt level handling or from the normal tasking
* level. Interrupts may need to be disabled internally to assure
* non-reentrancy.
*
****************************************************************************/
#ifdef CONFIG_SCHED_TICKLESS
int up_timer_cancel(FAR struct timespec *ts)
{
/* Return the time remaining on the simulated timer */
if (g_timer_active)
{
ts->tv_sec = g_interval_delay.tv_sec;
ts->tv_nsec = g_interval_delay.tv_nsec;
}
else
{
ts->tv_sec = 0;
ts->tv_nsec = 0;
}
/* Disable and reset the simulated timer */
g_interval_delay.tv_sec = 0;
g_interval_delay.tv_nsec = 0;
g_timer_active = false;
}
#endif
/****************************************************************************
* Name: up_timer_start
*
* Description:
* Start the interval timer. sched_timer_expiration() will be
* called at the completion of the timeout (unless up_timer_cancel
* is called to stop the timing.
*
* Provided by platform-specific code and called from the RTOS base code.
*
* Input Parameters:
* ts - Provides the time interval until sched_timer_expiration() is
* called.
*
* Returned Value:
* Zero (OK) is returned on success; a negated errno value is returned on
* any failure.
*
* Assumptions:
* May be called from interrupt level handling or from the normal tasking
* level. Interrupts may need to be disabled internally to assure
* non-reentrancy.
*
****************************************************************************/
#ifdef CONFIG_SCHED_TICKLESS
int up_timer_start(FAR const struct timespec *ts)
{
g_interval_delay.tv_sec = ts->tv_sec;
g_interval_delay.tv_nsec = ts->tv_nsec;
g_timer_active = true;
}
#endif
/****************************************************************************
* Name: up_timer_update
*
* Description:
* Called from the IDLE loop to fake one timer tick.
*
* Input Parameters:
* None
*
* Returned Value:
* None
*
****************************************************************************/
void up_timer_update(void)
{
/* Increment the elapsed time */
g_elapsed_time.tv_nsec += TICK_NSEC;
if (g_elapsed_time.tv_nsec >= NSEC_PER_SEC)
{
g_elapsed_time.tv_sec++;
g_elapsed_time.tv_nsec -= NSEC_PER_SEC;
}
g_elapsed_time.tv_sec += TICK_SEC;
/* Is the interval timer active? */
if (g_timer_active)
{
/* Yes... decrement the interval timer */
if (g_interval_delay.tv_sec < TICK_SEC)
{
/* No more seconds left... the timer has expired */
g_timer_active = false;
sched_timer_expiration();
}
else
{
/* Decrement seconds. May decrement to zero */
g_interval_delay.tv_sec -= TICK_SEC;
/* Decrement nanoseconds */
if (g_interval_delay.tv_nsec >= TICK_NSEC)
{
g_interval_delay.tv_nsec -= TICK_NSEC;
}
/* Handle borrow from seconds */
else if (g_interval_delay.tv_sec > 0)
{
g_interval_delay.tv_nsec += NSEC_PER_SEC;
g_interval_delay.tv_sec--;
g_interval_delay.tv_nsec -= TICK_NSEC;
}
/* Otherwise the timer has expired */
else
{
g_timer_active = false;
sched_timer_expiration();
}
}
}
}
#endif /* CONFIG_SCHED_TICKLESS */
