/**************************************************************************** * arch/arm/src/sam34/sam_tickless.c * * Copyright (C) 2015 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * 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 #include #include #include #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 */