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;
}
int sam_oneshot_start(struct sam_oneshot_s *oneshot, oneshot_handler_t handler,
void *arg, const struct timespec *ts)
{
uint64_t usec;
uint64_t regval;
irqstate_t flags;
tcvdbg("handler=%p arg=%p, ts=(%lu, %lu)\n",
handler, arg, (unsigned long)ts->tv_sec, (unsigned long)ts->tv_nsec);
DEBUGASSERT(oneshot && handler && ts);
/* Was the oneshot already running? */
flags = irqsave();
if (oneshot->running)
{
/* Yes.. then cancel it */
tcvdbg("Already running... cancelling\n");
(void)sam_oneshot_cancel(oneshot, NULL);
}
/* Save the new handler and its argument */
oneshot->handler = handler;
oneshot->arg = arg;
/* Express the delay in microseconds */
usec = (uint64_t)ts->tv_sec * USEC_PER_SEC + (uint64_t)(ts->tv_nsec / NSEC_PER_USEC);
/* Get the timer counter frequency and determine the number of counts need to achieve the requested delay.
*
* frequency = ticks / second
* ticks = seconds * frequency
* = (usecs * frequency) / USEC_PER_SEC;
*/
regval = (usec * (uint64_t)sam_tc_divfreq(oneshot->tch)) / USEC_PER_SEC;
tcvdbg("usec=%llu regval=%08llx\n", usec, regval);
DEBUGASSERT(regval <= UINT32_MAX);
/* Set up to receive the callback when the interrupt occurs */
(void)sam_tc_attach(oneshot->tch, sam_oneshot_handler, oneshot,
TC_INT_CPCS);
/* Set RC so that an event will be triggered when TC_CV register counts
* up to RC.
*/
sam_tc_setregister(oneshot->tch, TC_REGC, (uint32_t)regval);
/* Start the counter */
sam_tc_start(oneshot->tch);
/* Enable interrupts. We should get the callback when the interrupt
* occurs.
*/
oneshot->running = true;
irqrestore(flags);
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_freerun_counter(struct sam_freerun_s *freerun, struct timespec *ts)
{
uint64_t usec;
uint32_t counter;
uint32_t verify;
uint32_t sr;
uint32_t overflow;
uint32_t sec;
irqstate_t flags;
DEBUGASSERT(freerun && freerun->tch && ts);
/* Temporarily disable the overflow counter */
flags = irqsave();
overflow = freerun->overflow;
counter = sam_tc_getcounter(freerun->tch);
sr = sam_tc_getpending(freerun->tch);
verify = sam_tc_getcounter(freerun->tch);
irqrestore(flags);
tcvdbg("counter=%lu (%lu) overflow=%lu, sr=%08lx\n",
(unsigned long)counter, (unsigned long)verify,
(unsigned long)overflow, (unsigned long)sr);
/* If an interrupt was pending before we re-enabled interrupts,
* then our value of overflow needs to be incremented.
*/
if ((sr & TC_INT_COVFS) != 0)
{
/* Increment the overflow count and use the value of the
* guaranteed to be AFTER the overflow occurred.
*/
overflow++;
counter = verify;
tcvdbg("counter=%lu overflow=%lu\n",
(unsigned long)counter, (unsigned long)overflow);
}
/* Convert the whole thing to units of microseconds.
*
* frequency = ticks / second
* seconds = ticks * frequency
* usecs = (ticks * USEC_PER_SEC) / frequency;
*/
usec = ((((uint64_t)overflow << 32) + (uint64_t)counter) * USEC_PER_SEC) /
sam_tc_divfreq(freerun->tch);
/* And return the value of the timer */
sec = (uint32_t)(usec / USEC_PER_SEC);
ts->tv_sec = sec;
ts->tv_nsec = (usec - (sec * USEC_PER_SEC)) * NSEC_PER_USEC;
tcvdbg("usec=%llu ts=(%lu, %lu)\n",
usec, (unsigned long)ts->tv_sec, (unsigned long)ts->tv_nsec);
return OK;
}
int sam_oneshot_start(struct sam_oneshot_s *oneshot, struct sam_freerun_s *freerun,
oneshot_handler_t handler, void *arg, const struct timespec *ts)
{
uint64_t usec;
uint64_t regval;
irqstate_t flags;
tmrinfo("handler=%p arg=%p, ts=(%lu, %lu)\n",
handler, arg, (unsigned long)ts->tv_sec, (unsigned long)ts->tv_nsec);
DEBUGASSERT(oneshot && handler && ts);
/* Was the oneshot already running? */
flags = enter_critical_section();
if (oneshot->running)
{
/* Yes.. then cancel it */
tmrinfo("Already running... cancelling\n");
(void)sam_oneshot_cancel(oneshot, freerun, NULL);
}
/* Save the new handler and its argument */
oneshot->handler = handler;
oneshot->arg = arg;
/* Express the delay in microseconds */
usec = (uint64_t)ts->tv_sec * USEC_PER_SEC + (uint64_t)(ts->tv_nsec / NSEC_PER_USEC);
/* Get the timer counter frequency and determine the number of counts need to achieve the requested delay.
*
* frequency = ticks / second
* ticks = seconds * frequency
* = (usecs * frequency) / USEC_PER_SEC;
*/
regval = (usec * (uint64_t)sam_tc_divfreq(oneshot->tch)) / USEC_PER_SEC;
tmrinfo("usec=%llu regval=%08llx\n", usec, regval);
DEBUGASSERT(regval <= UINT32_MAX);
/* Set up to receive the callback when the interrupt occurs */
(void)sam_tc_attach(oneshot->tch, sam_oneshot_handler, oneshot,
TC_INT_CPCS);
/* Set RC so that an event will be triggered when TC_CV register counts
* up to RC.
*/
sam_tc_setregister(oneshot->tch, TC_REGC, (uint32_t)regval);
/* Start the counter */
sam_tc_start(oneshot->tch);
/* The function sam_tc_start() starts the timer/counter by setting the
* bits TC_CCR_CLKEN and TC_CCR_SWTRG in the channel control register.
* The first one enables the timer/counter the latter performs an
* software trigger, which starts the clock and sets the counter
* register to zero. This reset is performed with the next valid edge
* of the selected clock. Thus it can take up USEC_PER_TICK microseconds
* until the counter register becomes zero.
*
* If the timer is canceled within this period the counter register holds
* the counter value for the last timer/counter run. To circumvent this
* the counter value of the freerun timer/counter is stored at each start
* of the oneshot timer/counter.
*
* The function up_timer_gettime() could also be used for this but it takes
* too long. If up_timer_gettime() is called within this function the problem
* vanishes at least if compiled with no optimisation.
*/
oneshot->start_count = sam_tc_getcounter(freerun->tch);
/* Enable interrupts. We should get the callback when the interrupt
* occurs.
*/
oneshot->running = true;
leave_critical_section(flags);
return OK;
}
