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- /****************************************************************************
- * drivers/timers/arch_timer.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.
- *
- ****************************************************************************/
- /****************************************************************************
- * Included Files
- ****************************************************************************/
- #include <nuttx/config.h>
- #include <nuttx/arch.h>
- #include <nuttx/clock.h>
- #include <nuttx/timers/arch_timer.h>
- /****************************************************************************
- * Pre-processor Definitions
- ****************************************************************************/
- #if defined(CONFIG_SCHED_TICKLESS) && defined(CONFIG_SCHED_TICKLESS_ALARM)
- # error CONFIG_SCHED_TICKLESS_ALARM must be unset to use the arch timer
- #endif
- #define CONFIG_BOARD_LOOPSPER100USEC ((CONFIG_BOARD_LOOPSPERMSEC+5)/10)
- #define CONFIG_BOARD_LOOPSPER10USEC ((CONFIG_BOARD_LOOPSPERMSEC+50)/100)
- #define CONFIG_BOARD_LOOPSPERUSEC ((CONFIG_BOARD_LOOPSPERMSEC+500)/1000)
- #define TIMER_START(l) ((l)->ops->start(l))
- #define TIMER_GETSTATUS(l,s) ((l)->ops->getstatus(l,s))
- #define TIMER_SETTIMEOUT(l,t) ((l)->ops->settimeout(l,t))
- #define TIMER_SETCALLBACK(l,c,a) ((l)->ops->setcallback(l,c,a))
- #define TIMER_MAXTIMEOUT(l,t) ((l)->ops->maxtimeout(l,t))
- /****************************************************************************
- * Private Types
- ****************************************************************************/
- struct arch_timer_s
- {
- FAR struct timer_lowerhalf_s *lower;
- uint32_t *next_interval;
- uint32_t maxtimeout;
- uint64_t timebase;
- };
- /****************************************************************************
- * Private Data
- ****************************************************************************/
- static struct arch_timer_s g_timer;
- /****************************************************************************
- * Private Functions
- ****************************************************************************/
- #if defined(CONFIG_SCHED_TICKLESS) || defined(CONFIG_SCHED_CRITMONITOR) \
- || defined(CONFIG_SCHED_IRQMONITOR_GETTIME)
- static inline void timespec_from_usec(FAR struct timespec *ts,
- uint64_t microseconds)
- {
- ts->tv_sec = microseconds / USEC_PER_SEC;
- microseconds -= (uint64_t)ts->tv_sec * USEC_PER_SEC;
- ts->tv_nsec = microseconds * NSEC_PER_USEC;
- }
- #endif
- #ifdef CONFIG_SCHED_TICKLESS
- static inline uint64_t timespec_to_usec(const FAR struct timespec *ts)
- {
- return (uint64_t)ts->tv_sec * USEC_PER_SEC + ts->tv_nsec / NSEC_PER_USEC;
- }
- static inline bool timeout_diff(uint32_t new, uint32_t old)
- {
- return new < old ? old - new >= USEC_PER_TICK : new - old >= USEC_PER_TICK;
- }
- static uint32_t update_timeout(uint32_t timeout)
- {
- struct timer_status_s status;
- /* Don't need critical section here
- * since caller already do it for us
- */
- TIMER_GETSTATUS(g_timer.lower, &status);
- if (g_timer.next_interval)
- {
- /* If the timer interrupt is in the process,
- * let the callback return the right interval.
- */
- *g_timer.next_interval = timeout;
- }
- else if (timeout_diff(timeout, status.timeleft))
- {
- /* Otherwise, update the timeout directly. */
- TIMER_SETTIMEOUT(g_timer.lower, timeout);
- g_timer.timebase += status.timeout - status.timeleft;
- }
- return status.timeleft;
- }
- #endif
- static uint64_t current_usec(void)
- {
- struct timer_status_s status;
- uint64_t timebase;
- do
- {
- timebase = g_timer.timebase;
- TIMER_GETSTATUS(g_timer.lower, &status);
- }
- while (timebase != g_timer.timebase);
- return timebase + (status.timeout - status.timeleft);
- }
- static void udelay_accurate(useconds_t microseconds)
- {
- uint64_t start = current_usec();
- while (current_usec() - start < microseconds)
- {
- ; /* Wait until the timeout reach */
- }
- }
- static void udelay_coarse(useconds_t microseconds)
- {
- volatile int i;
- /* We'll do this a little at a time because we expect that the
- * CONFIG_BOARD_LOOPSPERUSEC is very inaccurate during to truncation in
- * the divisions of its calculation. We'll use the largest values that
- * we can in order to prevent significant error buildup in the loops.
- */
- while (microseconds > 1000)
- {
- for (i = 0; i < CONFIG_BOARD_LOOPSPERMSEC; i++)
- {
- }
- microseconds -= 1000;
- }
- while (microseconds > 100)
- {
- for (i = 0; i < CONFIG_BOARD_LOOPSPER100USEC; i++)
- {
- }
- microseconds -= 100;
- }
- while (microseconds > 10)
- {
- for (i = 0; i < CONFIG_BOARD_LOOPSPER10USEC; i++)
- {
- }
- microseconds -= 10;
- }
- while (microseconds > 0)
- {
- for (i = 0; i < CONFIG_BOARD_LOOPSPERUSEC; i++)
- {
- }
- microseconds--;
- }
- }
- static bool timer_callback(FAR uint32_t *next_interval_us, FAR void *arg)
- {
- #ifdef CONFIG_SCHED_TICKLESS
- struct timer_status_s status;
- uint32_t next_interval;
- g_timer.timebase += *next_interval_us;
- next_interval = g_timer.maxtimeout;
- g_timer.next_interval = &next_interval;
- nxsched_timer_expiration();
- g_timer.next_interval = NULL;
- TIMER_GETSTATUS(g_timer.lower, &status);
- if (timeout_diff(next_interval, status.timeleft))
- {
- g_timer.timebase += status.timeout - status.timeleft;
- *next_interval_us = next_interval;
- }
- #else
- g_timer.timebase += USEC_PER_TICK;
- nxsched_process_timer();
- #endif
- return true;
- }
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- void up_timer_set_lowerhalf(FAR struct timer_lowerhalf_s *lower)
- {
- g_timer.lower = lower;
- TIMER_MAXTIMEOUT(g_timer.lower, &g_timer.maxtimeout);
- #ifdef CONFIG_SCHED_TICKLESS
- g_oneshot_maxticks = g_timer.maxtimeout / USEC_PER_TICK;
- TIMER_SETTIMEOUT(g_timer.lower, g_timer.maxtimeout);
- #else
- TIMER_SETTIMEOUT(g_timer.lower, USEC_PER_TICK);
- #endif
- TIMER_SETCALLBACK(g_timer.lower, timer_callback, NULL);
- TIMER_START(g_timer.lower);
- }
- /****************************************************************************
- * Name: up_timer_gettime
- *
- * Description:
- * Return the elapsed time since power-up (or, more correctly, since
- * the architecture-specific timer was initialized). 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 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.
- *
- ****************************************************************************/
- #ifdef CONFIG_CLOCK_TIMEKEEPING
- int up_timer_getcounter(FAR uint64_t *cycles)
- {
- int ret = -EAGAIN;
- if (g_timer.lower != NULL)
- {
- *cycles = current_usec() / USEC_PER_TICK;
- ret = 0;
- }
- return ret;
- }
- void up_timer_getmask(FAR uint64_t *mask)
- {
- uint32_t maxticks = g_timer.maxtimeout / USEC_PER_TICK;
- *mask = 0;
- while (1)
- {
- uint64_t next = (*mask << 1) | 1;
- if (next > maxticks)
- {
- break;
- }
- *mask = next;
- }
- }
- #endif
- #if defined(CONFIG_SCHED_TICKLESS)
- int up_timer_gettime(FAR struct timespec *ts)
- {
- int ret = -EAGAIN;
- if (g_timer.lower != NULL)
- {
- timespec_from_usec(ts, current_usec());
- ret = 0;
- }
- return ret;
- }
- #endif
- /****************************************************************************
- * 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.
- *
- ****************************************************************************/
- #ifdef CONFIG_SCHED_TICKLESS
- int up_timer_cancel(FAR struct timespec *ts)
- {
- int ret = -EAGAIN;
- if (g_timer.lower != NULL)
- {
- timespec_from_usec(ts, update_timeout(g_timer.maxtimeout));
- ret = 0;
- }
- return ret;
- }
- #endif
- /****************************************************************************
- * 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.
- *
- ****************************************************************************/
- #ifdef CONFIG_SCHED_TICKLESS
- int up_timer_start(FAR const struct timespec *ts)
- {
- int ret = -EAGAIN;
- if (g_timer.lower != NULL)
- {
- update_timeout(timespec_to_usec(ts));
- ret = 0;
- }
- return ret;
- }
- #endif
- /****************************************************************************
- * Name: up_critmon_*
- *
- * Description:
- * The first interface simply provides the current time value in unknown
- * units. NOTE: This function may be called early before the timer has
- * been initialized. In that event, the function should just return a
- * start time of zero.
- *
- * Nothing is assumed about the units of this time value. The following
- * are assumed, however: (1) The time is an unsigned integer value, (2)
- * the time is monotonically increasing, and (3) the elapsed time (also
- * in unknown units) can be obtained by subtracting a start time from
- * the current time.
- *
- * The second interface simple converts an elapsed time into well known
- * units.
- ****************************************************************************/
- #ifdef CONFIG_SCHED_CRITMONITOR
- uint32_t up_critmon_gettime(void)
- {
- uint32_t ret = 0;
- if (g_timer.lower != NULL)
- {
- ret = current_usec();
- }
- return ret;
- }
- void up_critmon_convert(uint32_t elapsed, FAR struct timespec *ts)
- {
- timespec_from_usec(ts, elapsed);
- }
- #endif
- /****************************************************************************
- * Name: up_mdelay
- *
- * Description:
- * Delay inline for the requested number of milliseconds.
- * *** NOT multi-tasking friendly ***
- *
- ****************************************************************************/
- void up_mdelay(unsigned int milliseconds)
- {
- up_udelay(USEC_PER_MSEC * milliseconds);
- }
- /****************************************************************************
- * Name: up_udelay
- *
- * Description:
- * Delay inline for the requested number of microseconds.
- *
- * *** NOT multi-tasking friendly ***
- *
- ****************************************************************************/
- void up_udelay(useconds_t microseconds)
- {
- if (g_timer.lower != NULL)
- {
- udelay_accurate(microseconds);
- }
- else /* Period timer hasn't been initialized yet */
- {
- udelay_coarse(microseconds);
- }
- }
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