static void sam_oneshot_handler(TC_HANDLE tch, void *arg, uint32_t sr)
{
struct sam_oneshot_s *oneshot = (struct sam_oneshot_s *)arg;
oneshot_handler_t oneshot_handler;
void *oneshot_arg;
tmrinfo("Expired...\n");
DEBUGASSERT(oneshot && oneshot->handler);
/* The clock was stopped, but not disabled when the RC match occurred.
* Disable the TC now and disable any further interrupts.
*/
sam_tc_attach(oneshot->tch, NULL, NULL, 0);
sam_tc_stop(oneshot->tch);
/* The timer is no longer running */
oneshot->running = false;
/* Forward the event, clearing out any vestiges */
oneshot_handler = (oneshot_handler_t)oneshot->handler;
oneshot->handler = NULL;
oneshot_arg = (void *)oneshot->arg;
oneshot->arg = NULL;
oneshot->start_count = 0;
oneshot_handler(oneshot_arg);
}
int sam_freerun_uninitialize(struct sam_freerun_s *freerun)
{
DEBUGASSERT(freerun && freerun->tch);
/* Now we can disable the timer interrupt and disable the timer. */
sam_tc_attach(freerun->tch, NULL, NULL, 0);
sam_tc_stop(freerun->tch);
/* Free the timer */
sam_tc_free(freerun->tch);
freerun->tch = NULL;
return OK;
}
int sam_oneshot_cancel(struct sam_oneshot_s *oneshot, struct sam_freerun_s *freerun,
struct timespec *ts)
{
irqstate_t flags;
uint64_t usec;
uint64_t sec;
uint64_t nsec;
uint32_t count;
uint32_t rc;
/* Was the timer running? */
flags = enter_critical_section();
if (!oneshot->running)
{
/* No.. Just return zero timer remaining and successful cancellation.
* This function may execute at a high rate with no timer running
* (as when pre-emption is enabled and disabled).
*/
ts->tv_sec = 0;
ts->tv_nsec = 0;
leave_critical_section(flags);
return OK;
}
/* Yes.. Get the timer counter and rc registers and stop the counter. If
* the counter expires while we are doing this, the counter clock will be
* stopped, but the clock will not be disabled.
*
* The expected behavior is that the the counter register will freezes at
* a value equal to the RC register when the timer expires. The counter
* should have values between 0 and RC in all other cased.
*
* REVISIT: This does not appear to be the case.
*/
tmrinfo("Cancelling...\n");
count = sam_tc_getcounter(oneshot->tch);
rc = sam_tc_getregister(oneshot->tch, TC_REGC);
/* In the case the timer/counter was canceled very short after its start,
* the counter register can hold the wrong value (the value of the last
* run). To prevent this the counter value is set to zero if not at
* least on tick passed since the start of the timer/counter.
*/
if (count > 0 && sam_tc_getcounter(freerun->tch) == oneshot->start_count)
{
count = 0;
}
/* Now we can disable the interrupt and stop the timer. */
sam_tc_attach(oneshot->tch, NULL, NULL, 0);
sam_tc_stop(oneshot->tch);
oneshot->running = false;
oneshot->handler = NULL;
oneshot->arg = NULL;
leave_critical_section(flags);
/* Did the caller provide us with a location to return the time
* remaining?
*/
if (ts)
{
/* Yes.. then calculate and return the time remaining on the
* oneshot timer.
*/
tmrinfo("rc=%lu count=%lu usec=%lu\n",
(unsigned long)rc, (unsigned long)count, (unsigned long)usec);
/* REVISIT: I am not certain why the timer counter value sometimes
* exceeds RC. Might be a bug, or perhaps the counter does not stop
* in all cases.
*/
if (count >= rc)
{
/* No time remaining (?) */
ts->tv_sec = 0;
ts->tv_nsec = 0;
}
else
{
/* The total time remaining is the difference. Convert the that
* to units of microseconds.
*
* frequency = ticks / second
* seconds = ticks * frequency
* usecs = (ticks * USEC_PER_SEC) / frequency;
*/
usec = (((uint64_t)(rc - count)) * USEC_PER_SEC) /
sam_tc_divfreq(oneshot->tch);
/* Each time the timer/counter is canceled the time calculated from
* the two registers (counter and REGC) is accurate up to an error
* between 0 and USEC_PER_TICK microseconds. To correct this error
* one tick which means USEC_PER_TICK microseconds are subtracted.
*/
usec = usec > USEC_PER_TICK ? usec - USEC_PER_TICK : 0;
/* Return the time remaining in the correct form */
sec = usec / USEC_PER_SEC;
nsec = ((usec) - (sec * USEC_PER_SEC)) * NSEC_PER_USEC;
ts->tv_sec = (time_t)sec;
ts->tv_nsec = (unsigned long)nsec;
}
tmrinfo("remaining (%lu, %lu)\n",
(unsigned long)ts->tv_sec, (unsigned long)ts->tv_nsec);
}
return OK;
}
int sam_oneshot_cancel(struct sam_oneshot_s *oneshot, struct timespec *ts)
{
irqstate_t flags;
uint64_t usec;
uint64_t sec;
uint64_t nsec;
uint32_t count;
uint32_t rc;
/* Was the timer running? */
flags = irqsave();
if (!oneshot->running)
{
/* No.. Just return zero timer remaining and successful cancellation.
* This function may execute at a high rate with no timer running
* (as when pre-emption is enabled and disabled).
*/
ts->tv_sec = 0;
ts->tv_nsec = 0;
irqrestore(flags);
return OK;
}
/* Yes.. Get the timer counter and rc registers and stop the counter. If
* the counter expires while we are doing this, the counter clock will be
* stopped, but the clock will not be disabled.
*
* The expected behavior is that the the counter register will freezes at
* a value equal to the RC register when the timer expires. The counter
* should have values between 0 and RC in all other cased.
*
* REVISIT: This does not appear to be the case.
*/
tcvdbg("Cancelling...\n");
count = sam_tc_getcounter(oneshot->tch);
rc = sam_tc_getregister(oneshot->tch, TC_REGC);
/* Now we can disable the interrupt and stop the timer. */
sam_tc_attach(oneshot->tch, NULL, NULL, 0);
sam_tc_stop(oneshot->tch);
oneshot->running = false;
oneshot->handler = NULL;
oneshot->arg = NULL;
irqrestore(flags);
/* Did the caller provide us with a location to return the time
* remaining?
*/
if (ts)
{
/* Yes.. then calculate and return the time remaining on the
* oneshot timer.
*/
tcvdbg("rc=%lu count=%lu usec=%lu\n",
(unsigned long)rc, (unsigned long)count, (unsigned long)usec);
/* REVISIT: I am not certain why the timer counter value sometimes
* exceeds RC. Might be a bug, or perhaps the counter does not stop
* in all cases.
*/
if (count >= rc)
{
/* No time remaining (?) */
ts->tv_sec = 0;
ts->tv_nsec = 0;
}
else
{
/* The total time remaining is the difference. Convert the that
* to units of microseconds.
*
* frequency = ticks / second
* seconds = ticks * frequency
* usecs = (ticks * USEC_PER_SEC) / frequency;
*/
usec = (((uint64_t)(rc - count)) * USEC_PER_SEC) /
sam_tc_divfreq(oneshot->tch);
/* Return the time remaining in the correct form */
sec = usec / USEC_PER_SEC;
nsec = ((usec) - (sec * USEC_PER_SEC)) * NSEC_PER_USEC;
ts->tv_sec = (time_t)sec;
ts->tv_nsec = (unsigned long)nsec;
}
tcvdbg("remaining (%lu, %lu)\n",
(unsigned long)ts->tv_sec, (unsigned long)ts->tv_nsec);
}
return OK;
}
