* arch/arm/src/sama5/sam_tickless.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.
*
****************************************************************************/
* 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 initialization sequence (by up_initialize()).
* int up_timer_gettime(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(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 nxsched_timer_expiration(void): Called by the platform-specific
* logic when the interval timer expires.
*
****************************************************************************/
* SAMA5 Timer Usage
*
* This current implementation uses two timers: A one-shot timer to provide
* the timed events and a free running timer to provide the current time.
* Since timers are a limited resource, that could be an issue on some
* systems.
*
* We could do the job with a single timer if we were to keep the single
* timer in a free-running at all times. The SAMA5 timer/counters have
* 32-bit counters with the capability to generate a compare interrupt when
* the timer matches a compare value but also to continue counting without
* stopping (giving another, different interrupt when the timer rolls over
* from 0xffffffff to zero). So we could potentially just set the compare
* at the number of ticks you want PLUS the current value of timer. Then
* you could have both with a single timer: An interval timer and a free-
* running counter with the same timer!
*
* Patches are welcome!
*
****************************************************************************/
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdint.h>
#include <stdbool.h>
#include <assert.h>
#include <errno.h>
#include <nuttx/arch.h>
#include "sam_oneshot.h"
#include "sam_freerun.h"
#ifdef CONFIG_SCHED_TICKLESS
* Pre-processor Definitions
****************************************************************************/
#ifndef CONFIG_SAMA5_HAVE_TC
# error Timer/counters must be selected for the Tickless OS option
#endif
#ifndef CONFIG_SAMA5_ONESHOT
# error CONFIG_SAMA5_ONESHOT must be selected for the Tickless OS option
#endif
#ifndef CONFIG_SAMA5_FREERUN
# error CONFIG_SAMA5_FREERUN must be selected for the Tickless OS option
#endif
#ifndef CONFIG_SAMA5_TICKLESS_FREERUN
# error CONFIG_SAMA5_TICKLESS_FREERUN must be selected for the Tickless OS option
#endif
#ifndef CONFIG_SAMA5_TICKLESS_ONESHOT
# error CONFIG_SAMA5_TICKLESS_ONESHOT must be selected for the Tickless OS option
#endif
#if CONFIG_SAMA5_TICKLESS_ONESHOT == 0 && !defined(CONFIG_SAMA5_TC0)
# error CONFIG_SAMA5_TICKLESS_ONESHOT == 0 && CONFIG_SAMA5_TC0 not selected
#elif CONFIG_SAMA5_TICKLESS_ONESHOT == 1 && !defined(CONFIG_SAMA5_TC0)
# error CONFIG_SAMA5_TICKLESS_ONESHOT == 1 && CONFIG_SAMA5_TC0 not selected
#elif CONFIG_SAMA5_TICKLESS_ONESHOT == 2 && !defined(CONFIG_SAMA5_TC0)
# error CONFIG_SAMA5_TICKLESS_ONESHOT == 2 && CONFIG_SAMA5_TC0 not selected
#elif CONFIG_SAMA5_TICKLESS_ONESHOT == 3 && !defined(CONFIG_SAMA5_TC1)
# error CONFIG_SAMA5_TICKLESS_ONESHOT == 3 && CONFIG_SAMA5_TC1 not selected
#elif CONFIG_SAMA5_TICKLESS_ONESHOT == 4 && !defined(CONFIG_SAMA5_TC1)
# error CONFIG_SAMA5_TICKLESS_ONESHOT == 4 && CONFIG_SAMA5_TC1 not selected
#elif CONFIG_SAMA5_TICKLESS_ONESHOT == 5 && !defined(CONFIG_SAMA5_TC1)
# error CONFIG_SAMA5_TICKLESS_ONESHOT == 5 && CONFIG_SAMA5_TC1 not selected
#elif CONFIG_SAMA5_TICKLESS_ONESHOT == 6 && !defined(CONFIG_SAMA5_TC2)
# error CONFIG_SAMA5_TICKLESS_ONESHOT == 6 && CONFIG_SAMA5_TC2 not selected
#elif CONFIG_SAMA5_TICKLESS_ONESHOT == 7 && !defined(CONFIG_SAMA5_TC2)
# error CONFIG_SAMA5_TICKLESS_ONESHOT == 7 && CONFIG_SAMA5_TC2 not selected
#elif CONFIG_SAMA5_TICKLESS_ONESHOT == 8 && !defined(CONFIG_SAMA5_TC2)
# error CONFIG_SAMA5_TICKLESS_ONESHOT == 8 && CONFIG_SAMA5_TC2 not selected
#endif
#if CONFIG_SAMA5_TICKLESS_ONESHOT < 0 || CONFIG_SAMA5_TICKLESS_ONESHOT > 8
# error CONFIG_SAMA5_TICKLESS_ONESHOT is not valid
#endif
#if CONFIG_SAMA5_TICKLESS_FREERUN == 0 && !defined(CONFIG_SAMA5_TC0)
# error CONFIG_SAMA5_TICKLESS_FREERUN == 0 && CONFIG_SAMA5_TC0 not selected
#elif CONFIG_SAMA5_TICKLESS_FREERUN == 1 && !defined(CONFIG_SAMA5_TC0)
# error CONFIG_SAMA5_TICKLESS_FREERUN == 1 && CONFIG_SAMA5_TC0 not selected
#elif CONFIG_SAMA5_TICKLESS_FREERUN == 2 && !defined(CONFIG_SAMA5_TC0)
# error CONFIG_SAMA5_TICKLESS_FREERUN == 2 && CONFIG_SAMA5_TC0 not selected
#elif CONFIG_SAMA5_TICKLESS_FREERUN == 3 && !defined(CONFIG_SAMA5_TC1)
# error CONFIG_SAMA5_TICKLESS_FREERUN == 3 && CONFIG_SAMA5_TC1 not selected
#elif CONFIG_SAMA5_TICKLESS_FREERUN == 4 && !defined(CONFIG_SAMA5_TC1)
# error CONFIG_SAMA5_TICKLESS_FREERUN == 4 && CONFIG_SAMA5_TC1 not selected
#elif CONFIG_SAMA5_TICKLESS_FREERUN == 5 && !defined(CONFIG_SAMA5_TC1)
# error CONFIG_SAMA5_TICKLESS_FREERUN == 5 && CONFIG_SAMA5_TC1 not selected
#elif CONFIG_SAMA5_TICKLESS_FREERUN == 6 && !defined(CONFIG_SAMA5_TC2)
# error CONFIG_SAMA5_TICKLESS_FREERUN == 6 && CONFIG_SAMA5_TC2 not selected
#elif CONFIG_SAMA5_TICKLESS_FREERUN == 7 && !defined(CONFIG_SAMA5_TC2)
# error CONFIG_SAMA5_TICKLESS_FREERUN == 7 && CONFIG_SAMA5_TC2 not selected
#elif CONFIG_SAMA5_TICKLESS_FREERUN == 8 && !defined(CONFIG_SAMA5_TC2)
# error CONFIG_SAMA5_TICKLESS_FREERUN == 8 && CONFIG_SAMA5_TC2 not selected
#endif
#if CONFIG_SAMA5_TICKLESS_FREERUN < 0 || CONFIG_SAMA5_TICKLESS_FREERUN > 8
# error CONFIG_SAMA5_TICKLESS_FREERUN is not valid
#endif
#if CONFIG_SAMA5_TICKLESS_FREERUN == CONFIG_SAMA5_TICKLESS_ONESHOT
# error CONFIG_SAMA5_TICKLESS_FREERUN is the same as CONFIG_SAMA5_TICKLESS_ONESHOT
#endif
* Private Types
****************************************************************************/
struct sam_tickless_s
{
struct sam_oneshot_s oneshot;
struct sam_freerun_s freerun;
};
* Private Data
****************************************************************************/
static struct sam_tickless_s g_tickless;
* Private Functions
****************************************************************************/
* Name: sam_oneshot_handler
*
* Description:
* Called when the one shot timer expires
*
* Input Parameters:
* None
*
* Returned Value:
* None
*
* Assumptions:
* Called early in the initialization sequence before any special
* concurrency protections are required.
*
****************************************************************************/
static void sam_oneshot_handler(void *arg)
{
tmrinfo("Expired...\n");
nxsched_timer_expiration();
}
* Public Functions
****************************************************************************/
* Name: up_timer_initialize
*
* Description:
* Initializes all platform-specific timer facilities. This function is
* called early in the initialization sequence by up_initialize().
* 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)
{
#ifdef CONFIG_SCHED_TICKLESS_LIMIT_MAX_SLEEP
uint64_t max_delay;
#endif
int ret;
ret = sam_oneshot_initialize(&g_tickless.oneshot,
CONFIG_SAMA5_TICKLESS_ONESHOT,
CONFIG_USEC_PER_TICK);
if (ret < 0)
{
tmrerr("ERROR: sam_oneshot_initialize failed\n");
DEBUGPANIC();
}
DEBUGASSERT(ONESHOT_INITIALIZED(&g_tickless.oneshot));
#ifdef CONFIG_SCHED_TICKLESS_LIMIT_MAX_SLEEP
ret = sam_oneshot_max_delay(&g_tickless.oneshot, &max_delay);
if (ret < 0)
{
tmrerr("ERROR: sam_oneshot_max_delay failed\n");
DEBUGPANIC();
}
max_delay /= CONFIG_USEC_PER_TICK;
if (max_delay > (uint64_t)UINT32_MAX)
{
g_oneshot_maxticks = UINT32_MAX;
}
else
{
g_oneshot_maxticks = (uint32_t)max_delay;
}
#endif
ret = sam_freerun_initialize(&g_tickless.freerun,
CONFIG_SAMA5_TICKLESS_FREERUN,
CONFIG_USEC_PER_TICK);
if (ret < 0)
{
tmrerr("ERROR: sam_freerun_initialize failed\n");
DEBUGPANIC();
}
DEBUGASSERT(FREERUN_INITIALIZED(&g_tickless.freerun));
}
* 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, 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 errors 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 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(struct timespec *ts)
{
return FREERUN_INITIALIZED(&g_tickless.freerun) ?
sam_freerun_counter(&g_tickless.freerun, ts) :
-EAGAIN;
}
* 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.
* nxsched_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.
*
* NOTE: This function may execute at a high rate with no timer running (as
* when pre-emption is enabled and disabled).
*
* 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. ts may be zero in which case the
* time remaining is not returned.
*
* Returned Value:
* Zero (OK) is returned on success. A call to up_timer_cancel() when
* the timer is not active should also return 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.
*
****************************************************************************/
int up_timer_cancel(struct timespec *ts)
{
return ONESHOT_INITIALIZED(&g_tickless.oneshot) &&
FREERUN_INITIALIZED(&g_tickless.freerun) ?
sam_oneshot_cancel(&g_tickless.oneshot, &g_tickless.freerun, ts) :
-EAGAIN;
}
* Name: up_timer_start
*
* Description:
* Start the interval timer. nxsched_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 nxsched_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.
*
****************************************************************************/
int up_timer_start(const struct timespec *ts)
{
return ONESHOT_INITIALIZED(&g_tickless.oneshot) ?
sam_oneshot_start(&g_tickless.oneshot, &g_tickless.freerun,
sam_oneshot_handler, NULL, ts) : -EAGAIN;
}
#endif