394 lines
14 KiB
C
394 lines
14 KiB
C
/****************************************************************************
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* arch/arm/src/sam34/sam_tickless.c
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*
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* Copyright (C) 2015 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Tickless OS Support.
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*
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* When CONFIG_SCHED_TICKLESS is enabled, all support for timer interrupts
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* is suppressed and the platform specific code is expected to provide the
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* following custom functions.
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*
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* void up_timer_initialize(void): Initializes the timer facilities. Called
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* early in the initialization sequence (by up_intialize()).
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* int up_timer_gettime(FAR struct timespec *ts): Returns the current
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* time from the platform specific time source.
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* int up_timer_cancel(void): Cancels the interval timer.
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* int up_timer_start(FAR const struct timespec *ts): Start (or re-starts)
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* the interval timer.
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*
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* The RTOS will provide the following interfaces for use by the platform-
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* specific interval timer implementation:
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*
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* void sched_timer_expiration(void): Called by the platform-specific
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* logic when the interval timer expires.
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*
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****************************************************************************/
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/****************************************************************************
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* SAM34 Timer Usage
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*
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* This current implementation uses two timers: A one-shot timer to provide
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* the timed events and a free running timer to provide the current time.
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* Since timers are a limited resource, that could be an issue on some
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* systems.
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*
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* We could do the job with a single timer if we were to keep the single
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* timer in a free-running at all times. The SAM34 timer/counters have
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* 16-bit counters with the capability to generate a compare interrupt when
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* the timer matches a compare value but also to continue counting without
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* stopping (giving another, different interrupt when the timer rolls over
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* from 0xffff to zero). So we could potentially just set the compare
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* at the number of ticks you want PLUS the current value of timer. Then
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* you could have both with a single timer: An interval timer and a free-
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* running counter with the same timer!
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*
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* Patches are welcome!
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdint.h>
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#include <stdbool.h>
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#include <nuttx/arch.h>
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#include "sam4cm_oneshot.h"
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#include "sam4cm_freerun.h"
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#ifdef CONFIG_SCHED_TICKLESS
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#ifndef CONFIG_SAM34_TC
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# error Timer/counters must be selected for the Tickless OS option
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#endif
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#ifndef CONFIG_SAM34_ONESHOT
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# error CONFIG_SAM34_ONESHOT must be selected for the Tickless OS option
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#endif
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#ifndef CONFIG_SAM34_FREERUN
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# error CONFIG_SAM34_FREERUN must be selected for the Tickless OS option
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#endif
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#ifndef CONFIG_SAM34_TICKLESS_FREERUN
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# error CONFIG_SAM34_TICKLESS_FREERUN must be selected for the Tickless OS option
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#endif
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#ifndef CONFIG_SAM34_TICKLESS_ONESHOT
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# error CONFIG_SAM34_TICKLESS_ONESHOT must be selected for the Tickless OS option
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#endif
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#if CONFIG_SAM34_TICKLESS_ONESHOT == 0 && !defined(CONFIG_SAM34_TC0)
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# error CONFIG_SAM34_TICKLESS_ONESHOT == 0 && CONFIG_SAM34_TC0 not selected
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#elif CONFIG_SAM34_TICKLESS_ONESHOT == 1 && !defined(CONFIG_SAM34_TC0)
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# error CONFIG_SAM34_TICKLESS_ONESHOT == 1 && CONFIG_SAM34_TC0 not selected
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#elif CONFIG_SAM34_TICKLESS_ONESHOT == 2 && !defined(CONFIG_SAM34_TC0)
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# error CONFIG_SAM34_TICKLESS_ONESHOT == 2 && CONFIG_SAM34_TC0 not selected
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#elif CONFIG_SAM34_TICKLESS_ONESHOT == 3 && !defined(CONFIG_SAM34_TC1)
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# error CONFIG_SAM34_TICKLESS_ONESHOT == 3 && CONFIG_SAM34_TC1 not selected
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#elif CONFIG_SAM34_TICKLESS_ONESHOT == 4 && !defined(CONFIG_SAM34_TC1)
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# error CONFIG_SAM34_TICKLESS_ONESHOT == 4 && CONFIG_SAM34_TC1 not selected
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#elif CONFIG_SAM34_TICKLESS_ONESHOT == 5 && !defined(CONFIG_SAM34_TC1)
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# error CONFIG_SAM34_TICKLESS_ONESHOT == 5 && CONFIG_SAM34_TC1 not selected
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#endif
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#if CONFIG_SAM34_TICKLESS_ONESHOT < 0 || CONFIG_SAM34_TICKLESS_ONESHOT > 5
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# error CONFIG_SAMA5_TICKLESS_ONESHOT is not valid
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#endif
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#if CONFIG_SAM34_TICKLESS_FREERUN == 0 && !defined(CONFIG_SAM34_TC0)
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# error CONFIG_SAM34_TICKLESS_FREERUN == 0 && CONFIG_SAM34_TC0 not selected
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#elif CONFIG_SAM34_TICKLESS_FREERUN == 1 && !defined(CONFIG_SAM34_TC0)
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# error CONFIG_SAM34_TICKLESS_FREERUN == 1 && CONFIG_SAM34_TC0 not selected
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#elif CONFIG_SAM34_TICKLESS_FREERUN == 2 && !defined(CONFIG_SAM34_TC0)
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# error CONFIG_SAM34_TICKLESS_FREERUN == 2 && CONFIG_SAM34_TC0 not selected
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#elif CONFIG_SAM34_TICKLESS_FREERUN == 3 && !defined(CONFIG_SAM34_TC1)
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# error CONFIG_SAM34_TICKLESS_FREERUN == 3 && CONFIG_SAM34_TC1 not selected
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#elif CONFIG_SAM34_TICKLESS_FREERUN == 4 && !defined(CONFIG_SAM34_TC1)
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# error CONFIG_SAM34_TICKLESS_FREERUN == 4 && CONFIG_SAM34_TC1 not selected
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#elif CONFIG_SAM34_TICKLESS_FREERUN == 5 && !defined(CONFIG_SAM34_TC1)
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# error CONFIG_SAM34_TICKLESS_FREERUN == 5 && CONFIG_SAM34_TC1 not selected
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#endif
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#if CONFIG_SAM34_TICKLESS_FREERUN < 0 || CONFIG_SAM34_TICKLESS_FREERUN > 5
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# error CONFIG_SAM34_TICKLESS_FREERUN is not valid
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#endif
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#if CONFIG_SAM34_TICKLESS_FREERUN == CONFIG_SAM34_TICKLESS_ONESHOT
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# error CONFIG_SAM34_TICKLESS_FREERUN is the same as CONFIG_SAM34_TICKLESS_ONESHOT
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#endif
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/****************************************************************************
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* Private Types
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****************************************************************************/
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struct sam_tickless_s
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{
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struct sam_oneshot_s oneshot;
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struct sam_freerun_s freerun;
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};
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/****************************************************************************
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* Private Data
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****************************************************************************/
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static struct sam_tickless_s g_tickless;
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: sam_oneshot_handler
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*
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* Description:
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* Called when the one shot timer expires
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*
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* Input Parameters:
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* None
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*
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* Returned Value:
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* None
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*
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* Assumptions:
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* Called early in the initialization sequence before any special
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* concurrency protections are required.
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*
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****************************************************************************/
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static void sam_oneshot_handler(void *arg)
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{
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tcllvdbg("Expired...\n");
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sched_timer_expiration();
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: up_timer_initialize
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*
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* Description:
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* Initializes all platform-specific timer facilities. This function is
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* called early in the initialization sequence by up_intialize().
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* On return, the current up-time should be available from
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* up_timer_gettime() and the interval timer is ready for use (but not
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* actively timing.
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*
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* Provided by platform-specific code and called from the architecture-
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* specific logic.
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*
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* Input Parameters:
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* None
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*
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* Returned Value:
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* None
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*
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* Assumptions:
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* Called early in the initialization sequence before any special
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* concurrency protections are required.
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*
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****************************************************************************/
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void up_timer_initialize(void)
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{
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#ifdef CONFIG_SCHED_TICKLESS_LIMIT_MAX_SLEEP
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uint64_t max_delay;
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#endif
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int ret;
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/* Initialize the one-shot timer */
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ret = sam_oneshot_initialize(&g_tickless.oneshot,
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CONFIG_SAM34_TICKLESS_ONESHOT,
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CONFIG_USEC_PER_TICK);
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if (ret < 0)
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{
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tclldbg("ERROR: sam_oneshot_initialize failed\n");
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PANIC();
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}
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#ifdef CONFIG_SCHED_TICKLESS_LIMIT_MAX_SLEEP
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/* Get the maximum delay of the one-shot timer in microseconds */
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ret = sam_oneshot_max_delay(&g_tickless.oneshot, &max_delay);
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if (ret < 0)
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{
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tclldbg("ERROR: sam_oneshot_max_delay failed\n");
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PANIC();
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}
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/* Convert this to configured clock ticks for use by the OS timer logic */
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max_delay /= CONFIG_USEC_PER_TICK;
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if (max_delay > UINT32_MAX)
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{
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g_oneshot_maxticks = UINT32_MAX;
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}
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else
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{
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g_oneshot_maxticks = max_delay;
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}
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#endif
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/* Initialize the free-running timer */
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ret = sam_freerun_initialize(&g_tickless.freerun,
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CONFIG_SAM34_TICKLESS_FREERUN,
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CONFIG_USEC_PER_TICK);
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if (ret < 0)
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{
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tclldbg("ERROR: sam_freerun_initialize failed\n");
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PANIC();
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}
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}
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/****************************************************************************
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* Name: up_timer_gettime
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*
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* Description:
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* Return the elapsed time since power-up (or, more correctly, since
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* up_timer_initialize() was called). This function is functionally
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* equivalent to:
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*
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* int clock_gettime(clockid_t clockid, FAR struct timespec *ts);
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*
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* when clockid is CLOCK_MONOTONIC.
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*
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* This function provides the basis for reporting the current time and
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* also is used to eliminate error build-up from small errors in interval
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* time calculations.
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*
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* Provided by platform-specific code and called from the RTOS base code.
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*
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* Input Parameters:
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* ts - Provides the location in which to return the up-time.
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*
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* Returned Value:
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* Zero (OK) is returned on success; a negated errno value is returned on
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* any failure.
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*
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* Assumptions:
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* Called from the the normal tasking context. The implementation must
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* provide whatever mutual exclusion is necessary for correct operation.
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* This can include disabling interrupts in order to assure atomic register
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* operations.
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*
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****************************************************************************/
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int up_timer_gettime(FAR struct timespec *ts)
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{
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return sam_freerun_counter(&g_tickless.freerun, ts);
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}
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/****************************************************************************
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* Name: up_timer_cancel
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*
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* Description:
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* Cancel the interval timer and return the time remaining on the timer.
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* These two steps need to be as nearly atomic as possible.
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* sched_timer_expiration() will not be called unless the timer is
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* restarted with up_timer_start().
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*
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* If, as a race condition, the timer has already expired when this
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* function is called, then that pending interrupt must be cleared so
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* that up_timer_start() and the remaining time of zero should be
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* returned.
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*
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* NOTE: This function may execute at a high rate with no timer running (as
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* when pre-emption is enabled and disabled).
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*
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* Provided by platform-specific code and called from the RTOS base code.
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*
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* Input Parameters:
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* ts - Location to return the remaining time. Zero should be returned
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* if the timer is not active. ts may be zero in which case the
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* time remaining is not returned.
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*
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* Returned Value:
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* Zero (OK) is returned on success. A call to up_timer_cancel() when
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* the timer is not active should also return success; a negated errno
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* value is returned on any failure.
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*
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* Assumptions:
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* May be called from interrupt level handling or from the normal tasking
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* level. Interrupts may need to be disabled internally to assure
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* non-reentrancy.
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*
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****************************************************************************/
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int up_timer_cancel(FAR struct timespec *ts)
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{
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return sam_oneshot_cancel(&g_tickless.oneshot, ts);
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}
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/****************************************************************************
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* Name: up_timer_start
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*
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* Description:
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* Start the interval timer. sched_timer_expiration() will be
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* called at the completion of the timeout (unless up_timer_cancel
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* is called to stop the timing.
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*
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* Provided by platform-specific code and called from the RTOS base code.
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*
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* Input Parameters:
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* ts - Provides the time interval until sched_timer_expiration() is
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* called.
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*
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* Returned Value:
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* Zero (OK) is returned on success; a negated errno value is returned on
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* any failure.
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*
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* Assumptions:
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* May be called from interrupt level handling or from the normal tasking
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* level. Interrupts may need to be disabled internally to assure
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* non-reentrancy.
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*
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****************************************************************************/
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int up_timer_start(FAR const struct timespec *ts)
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{
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return sam_oneshot_start(&g_tickless.oneshot, sam_oneshot_handler, NULL, ts);
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}
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#endif /* CONFIG_SCHED_TICKLESS */
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