/****************************************************************************
* arch/arm/src/sam34/sam_tickless.c
*
* Copyright (C) 2015 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 initialization 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.
*
****************************************************************************/
/****************************************************************************
* SAM34 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 SAM34 timer/counters have
* 16-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 0xffff 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 <nuttx/arch.h>
#include "sam4cm_oneshot.h"
#include "sam4cm_freerun.h"
#ifdef CONFIG_SCHED_TICKLESS
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#ifndef CONFIG_SAM34_TC
# error Timer/counters must be selected for the Tickless OS option
#endif
#ifndef CONFIG_SAM34_ONESHOT
# error CONFIG_SAM34_ONESHOT must be selected for the Tickless OS option
#endif
#ifndef CONFIG_SAM34_FREERUN
# error CONFIG_SAM34_FREERUN must be selected for the Tickless OS option
#endif
#ifndef CONFIG_SAM34_TICKLESS_FREERUN
# error CONFIG_SAM34_TICKLESS_FREERUN must be selected for the Tickless OS option
#endif
#ifndef CONFIG_SAM34_TICKLESS_ONESHOT
# error CONFIG_SAM34_TICKLESS_ONESHOT must be selected for the Tickless OS option
#endif
#if CONFIG_SAM34_TICKLESS_ONESHOT == 0 && !defined(CONFIG_SAM34_TC0)
# error CONFIG_SAM34_TICKLESS_ONESHOT == 0 && CONFIG_SAM34_TC0 not selected
#elif CONFIG_SAM34_TICKLESS_ONESHOT == 1 && !defined(CONFIG_SAM34_TC0)
# error CONFIG_SAM34_TICKLESS_ONESHOT == 1 && CONFIG_SAM34_TC0 not selected
#elif CONFIG_SAM34_TICKLESS_ONESHOT == 2 && !defined(CONFIG_SAM34_TC0)
# error CONFIG_SAM34_TICKLESS_ONESHOT == 2 && CONFIG_SAM34_TC0 not selected
#elif CONFIG_SAM34_TICKLESS_ONESHOT == 3 && !defined(CONFIG_SAM34_TC1)
# error CONFIG_SAM34_TICKLESS_ONESHOT == 3 && CONFIG_SAM34_TC1 not selected
#elif CONFIG_SAM34_TICKLESS_ONESHOT == 4 && !defined(CONFIG_SAM34_TC1)
# error CONFIG_SAM34_TICKLESS_ONESHOT == 4 && CONFIG_SAM34_TC1 not selected
#elif CONFIG_SAM34_TICKLESS_ONESHOT == 5 && !defined(CONFIG_SAM34_TC1)
# error CONFIG_SAM34_TICKLESS_ONESHOT == 5 && CONFIG_SAM34_TC1 not selected
#endif
#if CONFIG_SAM34_TICKLESS_ONESHOT < 0 || CONFIG_SAM34_TICKLESS_ONESHOT > 5
# error CONFIG_SAMA5_TICKLESS_ONESHOT is not valid
#endif
#if CONFIG_SAM34_TICKLESS_FREERUN == 0 && !defined(CONFIG_SAM34_TC0)
# error CONFIG_SAM34_TICKLESS_FREERUN == 0 && CONFIG_SAM34_TC0 not selected
#elif CONFIG_SAM34_TICKLESS_FREERUN == 1 && !defined(CONFIG_SAM34_TC0)
# error CONFIG_SAM34_TICKLESS_FREERUN == 1 && CONFIG_SAM34_TC0 not selected
#elif CONFIG_SAM34_TICKLESS_FREERUN == 2 && !defined(CONFIG_SAM34_TC0)
# error CONFIG_SAM34_TICKLESS_FREERUN == 2 && CONFIG_SAM34_TC0 not selected
#elif CONFIG_SAM34_TICKLESS_FREERUN == 3 && !defined(CONFIG_SAM34_TC1)
# error CONFIG_SAM34_TICKLESS_FREERUN == 3 && CONFIG_SAM34_TC1 not selected
#elif CONFIG_SAM34_TICKLESS_FREERUN == 4 && !defined(CONFIG_SAM34_TC1)
# error CONFIG_SAM34_TICKLESS_FREERUN == 4 && CONFIG_SAM34_TC1 not selected
#elif CONFIG_SAM34_TICKLESS_FREERUN == 5 && !defined(CONFIG_SAM34_TC1)
# error CONFIG_SAM34_TICKLESS_FREERUN == 5 && CONFIG_SAM34_TC1 not selected
#endif
#if CONFIG_SAM34_TICKLESS_FREERUN < 0 || CONFIG_SAM34_TICKLESS_FREERUN > 5
# error CONFIG_SAM34_TICKLESS_FREERUN is not valid
#endif
#if CONFIG_SAM34_TICKLESS_FREERUN == CONFIG_SAM34_TICKLESS_ONESHOT
# error CONFIG_SAM34_TICKLESS_FREERUN is the same as CONFIG_SAM34_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)
{
tcllvdbg("Expired...\n");
sched_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_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)
{
#ifdef CONFIG_SCHED_TICKLESS_LIMIT_MAX_SLEEP
uint64_t max_delay;
#endif
int ret;
/* Initialize the one-shot timer */
ret = sam_oneshot_initialize(&g_tickless.oneshot,
CONFIG_SAM34_TICKLESS_ONESHOT,
CONFIG_USEC_PER_TICK);
if (ret < 0)
{
tclldbg("ERROR: sam_oneshot_initialize failed\n");
PANIC();
}
#ifdef CONFIG_SCHED_TICKLESS_LIMIT_MAX_SLEEP
/* Get the maximum delay of the one-shot timer in microseconds */
ret = sam_oneshot_max_delay(&g_tickless.oneshot, &max_delay);
if (ret < 0)
{
tclldbg("ERROR: sam_oneshot_max_delay failed\n");
PANIC();
}
/* Convert this to configured clock ticks for use by the OS timer logic */
max_delay /= CONFIG_USEC_PER_TICK;
if (max_delay > UINT32_MAX)
{
g_oneshot_maxticks = UINT32_MAX;
}
else
{
g_oneshot_maxticks = max_delay;
}
#endif
/* Initialize the free-running timer */
ret = sam_freerun_initialize(&g_tickless.freerun,
CONFIG_SAM34_TICKLESS_FREERUN,
CONFIG_USEC_PER_TICK);
if (ret < 0)
{
tclldbg("ERROR: sam_freerun_initialize failed\n");
PANIC();
}
}
/****************************************************************************
* 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 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 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)
{
return sam_freerun_counter(&g_tickless.freerun, ts);
}
/****************************************************************************
* 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.
*
* 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(FAR struct timespec *ts)
{
return sam_oneshot_cancel(&g_tickless.oneshot, ts);
}
/****************************************************************************
* 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.
*
****************************************************************************/
int up_timer_start(FAR const struct timespec *ts)
{
return sam_oneshot_start(&g_tickless.oneshot, sam_oneshot_handler, NULL, ts);
}
#endif /* CONFIG_SCHED_TICKLESS */
