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incubator-nuttx/sched/wdog/wd_start.c

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/****************************************************************************
* sched/wdog/wd_start.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 <sys/types.h>
#include <stdint.h>
#include <stdbool.h>
#include <unistd.h>
#include <sched.h>
#include <assert.h>
#include <errno.h>
#include <nuttx/irq.h>
#include <nuttx/arch.h>
#include <nuttx/wdog.h>
#include "sched/sched.h"
#include "wdog/wdog.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#ifndef MIN
# define MIN(a,b) (((a) < (b)) ? (a) : (b))
#endif
#ifndef MAX
# define MAX(a,b) (((a) > (b)) ? (a) : (b))
#endif
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: wd_expiration
*
* Description:
* Check if the timer for the watchdog at the head of list is ready to
* run. If so, remove the watchdog from the list and execute it.
*
* Input Parameters:
* None
*
* Returned Value:
* None
*
****************************************************************************/
static inline void wd_expiration(void)
{
FAR struct wdog_s *wdog;
/* Check if the watchdog at the head of the list is ready to run */
if (((FAR struct wdog_s *)g_wdactivelist.head)->lag <= 0)
{
/* Process the watchdog at the head of the list as well as any
* other watchdogs that became ready to run at this time
*/
while (g_wdactivelist.head &&
((FAR struct wdog_s *)g_wdactivelist.head)->lag <= 0)
{
/* Remove the watchdog from the head of the list */
wdog = (FAR struct wdog_s *)sq_remfirst(&g_wdactivelist);
/* If there is another watchdog behind this one, update its
* its lag (this shouldn't be necessary).
*/
if (g_wdactivelist.head)
{
((FAR struct wdog_s *)g_wdactivelist.head)->lag += wdog->lag;
}
/* Indicate that the watchdog is no longer active. */
WDOG_CLRACTIVE(wdog);
/* Execute the watchdog function */
up_setpicbase(wdog->picbase);
wdog->func(wdog->arg);
}
}
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: wd_start
*
* Description:
* This function adds a watchdog timer to the active timer queue. The
* specified watchdog function at 'wdentry' will be called from the
* interrupt level after the specified number of ticks has elapsed.
* Watchdog timers may be started from the interrupt level.
*
* Watchdog timers execute in the address environment that was in effect
* when wd_start() is called.
*
* Watchdog timers execute only once.
*
* To replace either the timeout delay or the function to be executed,
* call wd_start again with the same wdog; only the most recent wdStart()
* on a given watchdog ID has any effect.
*
* Input Parameters:
* wdog - Watchdog ID
* delay - Delay count in clock ticks
* wdentry - Function to call on timeout
* arg - Parameter to pass to wdentry
*
* NOTE: The parameter must be of type wdparm_t.
*
* Returned Value:
* Zero (OK) is returned on success; a negated errno value is return to
* indicate the nature of any failure.
*
* Assumptions:
* The watchdog routine runs in the context of the timer interrupt handler
* and is subject to all ISR restrictions.
*
****************************************************************************/
int wd_start(FAR struct wdog_s *wdog, int32_t delay,
wdentry_t wdentry, wdparm_t arg)
{
FAR struct wdog_s *curr;
FAR struct wdog_s *prev;
FAR struct wdog_s *next;
int32_t now;
irqstate_t flags;
/* Verify the wdog and setup parameters */
if (wdog == NULL || delay < 0)
{
return -EINVAL;
}
/* Check if the watchdog has been started. If so, stop it.
* NOTE: There is a race condition here... the caller may receive
* the watchdog between the time that wd_start is called and
* the critical section is established.
*/
flags = enter_critical_section();
if (WDOG_ISACTIVE(wdog))
{
wd_cancel(wdog);
}
/* Save the data in the watchdog structure */
wdog->func = wdentry; /* Function to execute when delay expires */
up_getpicbase(&wdog->picbase);
wdog->arg = arg;
/* Calculate delay+1, forcing the delay into a range that we can handle */
if (delay <= 0)
{
delay = 1;
}
else if (++delay <= 0)
{
delay--;
}
#ifdef CONFIG_SCHED_TICKLESS
/* Cancel the interval timer that drives the timing events. This will
* cause wd_timer to be called which update the delay value for the first
* time at the head of the timer list (there is a possibility that it
* could even remove it).
*/
nxsched_cancel_timer();
#endif
/* Do the easy case first -- when the watchdog timer queue is empty. */
if (g_wdactivelist.head == NULL)
{
#ifdef CONFIG_SCHED_TICKLESS
/* Update clock tickbase */
g_wdtickbase = clock_systime_ticks();
#endif
/* Add the watchdog to the head == tail of the queue. */
sq_addlast((FAR sq_entry_t *)wdog, &g_wdactivelist);
}
/* There are other active watchdogs in the timer queue */
else
{
now = 0;
prev = curr = (FAR struct wdog_s *)g_wdactivelist.head;
/* Advance to positive time */
while ((now += curr->lag) < 0 && curr->next)
{
prev = curr;
curr = curr->next;
}
/* Advance past shorter delays */
while (now <= delay && curr->next)
{
prev = curr;
curr = curr->next;
now += curr->lag;
}
/* Check if the new wdog must be inserted before the curr. */
if (delay < now)
{
/* The relative delay time is smaller or equal to the current delay
* time, so decrement the current delay time by the new relative
* delay time.
*/
delay -= (now - curr->lag);
curr->lag -= delay;
/* Insert the new watchdog in the list */
if (curr == (FAR struct wdog_s *)g_wdactivelist.head)
{
/* Insert the watchdog at the head of the list */
sq_addfirst((FAR sq_entry_t *)wdog, &g_wdactivelist);
}
else
{
/* Insert the watchdog in mid- or end-of-queue */
sq_addafter((FAR sq_entry_t *)prev, (FAR sq_entry_t *)wdog,
&g_wdactivelist);
}
}
/* The new watchdog delay time is greater than the curr delay time,
* so the new wdog must be inserted after the curr. This only occurs
* if the wdog is to be added to the end of the list.
*/
else
{
delay -= now;
if (!curr->next)
{
sq_addlast((FAR sq_entry_t *)wdog, &g_wdactivelist);
}
else
{
next = curr->next;
next->lag -= delay;
sq_addafter((FAR sq_entry_t *)curr, (FAR sq_entry_t *)wdog,
&g_wdactivelist);
}
}
}
/* Put the lag into the watchdog structure and mark it as active. */
wdog->lag = delay;
WDOG_SETACTIVE(wdog);
#ifdef CONFIG_SCHED_TICKLESS
/* Resume the interval timer that will generate the next interval event.
* If the timer at the head of the list changed, then this will pick that
* new delay.
*/
nxsched_resume_timer();
#endif
leave_critical_section(flags);
return OK;
}
/****************************************************************************
* Name: wd_timer
*
* Description:
* This function is called from the timer interrupt handler to determine
* if it is time to execute a watchdog function. If so, the watchdog
* function will be executed in the context of the timer interrupt
* handler.
*
* Input Parameters:
* ticks - If CONFIG_SCHED_TICKLESS is defined then the number of ticks
* in the interval that just expired is provided. Otherwise,
* this function is called on each timer interrupt and a value of one
* is implicit.
*
* Returned Value:
* If CONFIG_SCHED_TICKLESS is defined then the number of ticks for the
* next delay is provided (zero if no delay). Otherwise, this function
* has no returned value.
*
* Assumptions:
* Called from interrupt handler logic with interrupts disabled.
*
****************************************************************************/
#ifdef CONFIG_SCHED_TICKLESS
unsigned int wd_timer(int ticks)
{
FAR struct wdog_s *wdog;
#ifdef CONFIG_SMP
irqstate_t flags;
#endif
unsigned int ret;
int decr;
#ifdef CONFIG_SMP
/* We are in an interrupt handler as, as a consequence, interrupts are
* disabled. But in the SMP case, interrupts MAY be disabled only on
* the local CPU since most architectures do not permit disabling
* interrupts on other CPUS.
*
* Hence, we must follow rules for critical sections even here in the
* SMP case.
*/
flags = enter_critical_section();
#endif
/* Check if there are any active watchdogs to process */
while (g_wdactivelist.head != NULL && ticks > 0)
{
/* Get the watchdog at the head of the list */
wdog = (FAR struct wdog_s *)g_wdactivelist.head;
#ifndef CONFIG_SCHED_TICKLESS_ALARM
/* There is logic to handle the case where ticks is greater than
* the watchdog lag, but if the scheduling is working properly
* that should never happen.
*/
DEBUGASSERT(ticks <= wdog->lag);
#endif
/* Decrement the lag for this watchdog. */
decr = MIN(wdog->lag, ticks);
/* There are. Decrement the lag counter */
wdog->lag -= decr;
ticks -= decr;
g_wdtickbase += decr;
/* Check if the watchdog at the head of the list is ready to run */
wd_expiration();
}
/* Update clock tickbase */
g_wdtickbase += ticks;
/* Return the delay for the next watchdog to expire */
ret = g_wdactivelist.head ?
((FAR struct wdog_s *)g_wdactivelist.head)->lag : 0;
#ifdef CONFIG_SMP
leave_critical_section(flags);
#endif
/* Return the delay for the next watchdog to expire */
return ret;
}
#else
void wd_timer(void)
{
#ifdef CONFIG_SMP
irqstate_t flags;
/* We are in an interrupt handler as, as a consequence, interrupts are
* disabled. But in the SMP case, interrupts MAY be disabled only on
* the local CPU since most architectures do not permit disabling
* interrupts on other CPUS.
*
* Hence, we must follow rules for critical sections even here in the
* SMP case.
*/
flags = enter_critical_section();
#endif
/* Check if there are any active watchdogs to process */
if (g_wdactivelist.head)
{
/* There are. Decrement the lag counter */
--(((FAR struct wdog_s *)g_wdactivelist.head)->lag);
/* Check if the watchdog at the head of the list is ready to run */
wd_expiration();
}
#ifdef CONFIG_SMP
leave_critical_section(flags);
#endif
}
#endif /* CONFIG_SCHED_TICKLESS */
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