/
rtimer-arch.c
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/
rtimer-arch.c
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/*
* Copyright (c) 2012, Texas Instruments Incorporated - http://www.ti.com/
* All rights reserved.
*
* 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 of the copyright holder 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 HOLDER 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.
*/
/**
* \addtogroup cc2538-rtimer
* @{
*
* \file
* Implementation of the arch-specific rtimer functions for the cc2538
*
*/
#include "contiki.h"
#include "sys/energest.h"
#include "sys/rtimer.h"
#include "dev/nvic.h"
#include "dev/smwdthrosc.h"
#include "cpu.h"
#include "lpm.h"
#include <stdint.h>
/*---------------------------------------------------------------------------*/
static volatile rtimer_clock_t next_trigger;
/*---------------------------------------------------------------------------*/
/**
* \brief We don't need to explicitly initialise anything but this
* routine is required by the API.
*
* The Sleep Timer starts ticking automatically as soon as the device
* turns on. We don't need to turn on interrupts before the first call
* to rtimer_arch_schedule()
*/
void
rtimer_arch_init(void)
{
return;
}
/*---------------------------------------------------------------------------*/
/**
* \brief Schedules an rtimer task to be triggered at time t
* \param t The time when the task will need executed. This is an absolute
* time, in other words the task will be executed AT time \e t,
* not IN \e t ticks
*/
void
rtimer_arch_schedule(rtimer_clock_t t)
{
rtimer_clock_t now;
/* STLOAD must be 1 */
while((REG(SMWDTHROSC_STLOAD) & SMWDTHROSC_STLOAD_STLOAD) != 1);
INTERRUPTS_DISABLE();
now = RTIMER_NOW();
/*
* New value must be 5 ticks in the future. The ST may tick once while we're
* writing the registers. We play it safe here and we add a bit of leeway
*/
if((int32_t)(t - now) < 7) {
t = now + 7;
}
/* ST0 latches ST[1:3] and must be written last */
REG(SMWDTHROSC_ST3) = (t >> 24) & 0x000000FF;
REG(SMWDTHROSC_ST2) = (t >> 16) & 0x000000FF;
REG(SMWDTHROSC_ST1) = (t >> 8) & 0x000000FF;
REG(SMWDTHROSC_ST0) = t & 0x000000FF;
INTERRUPTS_ENABLE();
/* Store the value. The LPM module will query us for it */
next_trigger = t;
NVIC_EnableIRQ(SMT_IRQn);
}
/*---------------------------------------------------------------------------*/
rtimer_clock_t
rtimer_arch_next_trigger()
{
return next_trigger;
}
/*---------------------------------------------------------------------------*/
/**
* \brief Returns the current real-time clock time
* \return The current rtimer time in ticks
*/
rtimer_clock_t
rtimer_arch_now()
{
rtimer_clock_t rv;
/* SMWDTHROSC_ST0 latches ST[1:3] and must be read first */
rv = REG(SMWDTHROSC_ST0);
rv |= (REG(SMWDTHROSC_ST1) << 8);
rv |= (REG(SMWDTHROSC_ST2) << 16);
rv |= (REG(SMWDTHROSC_ST3) << 24);
return rv;
}
/*---------------------------------------------------------------------------*/
/**
* \brief The rtimer ISR
*
* Interrupts are only turned on when we have an rtimer task to schedule
* Once the interrupt fires, the task is called and then interrupts no
* longer get acknowledged until the next task needs scheduled.
*/
void
rtimer_isr()
{
/*
* If we were in PM1+, call the wake-up sequence first. This will make sure
* that the 32MHz OSC is selected as the clock source. We need to do this
* before calling the next rtimer_task, since the task may need the RF.
*/
lpm_exit();
ENERGEST_ON(ENERGEST_TYPE_IRQ);
next_trigger = 0;
NVIC_ClearPendingIRQ(SMT_IRQn);
NVIC_DisableIRQ(SMT_IRQn);
rtimer_run_next();
ENERGEST_OFF(ENERGEST_TYPE_IRQ);
}
/*---------------------------------------------------------------------------*/
/** @} */