nuttx/arch/sparc/src/bm3803/bm3803_oneshot.c

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/****************************************************************************
* arch/sparc/src/bm3803/bm3803_oneshot.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 <sys/types.h>
#include <stdint.h>
#include <stdbool.h>
#include <sched.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/irq.h>
#include <nuttx/clock.h>
#include "bm3803_oneshot.h"
#ifdef CONFIG_BM3803_ONESHOT
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static int bm3803_oneshot_handler(int irq, void *context, void *arg);
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: bm3803_oneshot_handler
*
* Description:
* Common timer interrupt callback. When any oneshot timer interrupt
* expires, this function will be called. It will forward the call to
* the next level up.
*
* Input Parameters:
* oneshot - The state associated with the expired timer
*
* Returned Value:
* Always returns OK
*
****************************************************************************/
static int bm3803_oneshot_handler(int irq, void *context, void *arg)
{
struct bm3803_oneshot_s *oneshot = (struct bm3803_oneshot_s *) arg;
oneshot_handler_t oneshot_handler;
void *oneshot_arg;
tmrinfo("Expired...\n");
DEBUGASSERT(oneshot != NULL && oneshot->handler);
/* The clock was stopped, but not disabled when the RC match occurred.
* Disable the TC now and disable any further interrupts.
*/
BM3803_TIM_SETISR(oneshot->tch, NULL, NULL, 0);
BM3803_TIM_SETMODE(oneshot->tch, BM3803_TIM_MODE_DISABLED);
BM3803_TIM_CLRINT(oneshot->tch, 0);
/* 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_handler(oneshot_arg);
return OK;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: bm3803_oneshot_initialize
*
* Description:
* Initialize the oneshot timer wrapper
*
* Input Parameters:
* oneshot Caller allocated instance of the oneshot state structure
* chan Timer counter channel to be used.
* resolution The required resolution of the timer in units of
* microseconds. NOTE that the range is restricted to the
* range of uint16_t (excluding zero).
*
* Returned Value:
* Zero (OK) is returned on success; a negated errno value is returned
* on failure.
*
****************************************************************************/
int bm3803_oneshot_initialize(struct bm3803_oneshot_s *oneshot,
int chan, uint16_t resolution)
{
uint32_t frequency;
tmrinfo("chan=%d resolution=%d usec\n", chan, resolution);
DEBUGASSERT(oneshot && resolution > 0);
/* Get the TC frequency the corresponds to the requested resolution */
frequency = USEC_PER_SEC / (uint32_t)resolution;
oneshot->frequency = frequency;
oneshot->tch = bm3803_tim_init(chan);
if (!oneshot->tch)
{
tmrerr("ERROR: Failed to allocate TIM%d\n", chan);
return -EBUSY;
}
BM3803_TIM_SETCLOCK(oneshot->tch, frequency);
/* Initialize the remaining fields in the state structure. */
oneshot->chan = chan;
oneshot->running = false;
oneshot->handler = NULL;
oneshot->arg = NULL;
/* Assign a callback handler to the oneshot */
return OK;
}
/****************************************************************************
* Name: bm3803_oneshot_max_delay
*
* Description:
* Determine the maximum delay of the one-shot timer (in microseconds)
*
****************************************************************************/
int bm3803_oneshot_max_delay(struct bm3803_oneshot_s *oneshot,
uint64_t *usec)
{
DEBUGASSERT(oneshot != NULL && usec != NULL);
*usec = (uint64_t)(UINT24_MAX / oneshot->frequency) *
(uint64_t)USEC_PER_SEC;
return OK;
}
/****************************************************************************
* Name: bm3803_oneshot_start
*
* Description:
* Start the oneshot timer
*
* Input Parameters:
* oneshot Caller allocated instance of the oneshot state structure. This
* structure must have been previously initialized via a call to
* bm3803_oneshot_initialize();
* handler The function to call when when the oneshot timer expires.
* arg An opaque argument that will accompany the callback.
* ts Provides the duration of the one shot timer.
*
* Returned Value:
* Zero (OK) is returned on success; a negated errno value is returned
* on failure.
*
****************************************************************************/
int bm3803_oneshot_start(struct bm3803_oneshot_s *oneshot,
oneshot_handler_t handler, void *arg,
const struct timespec *ts)
{
uint64_t usec;
uint64_t period;
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);
DEBUGASSERT(oneshot->tch);
/* Was the oneshot already running? */
flags = enter_critical_section();
if (oneshot->running)
{
/* Yes.. then cancel it */
tmrinfo("Already running... cancelling\n");
bm3803_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;
*/
period = (usec * (uint64_t)oneshot->frequency) / USEC_PER_SEC;
tmrinfo("usec=%llu period=%08llx\n", usec, period);
DEBUGASSERT(period <= UINT24_MAX);
/* Set up to receive the callback when the interrupt occurs */
BM3803_TIM_SETISR(oneshot->tch, bm3803_oneshot_handler, oneshot, 0);
/* Set timer period */
oneshot->period = (uint32_t)period;
BM3803_TIM_SETPERIOD(oneshot->tch, (uint32_t)period);
BM3803_TIM_CLRINT(oneshot->tch, 0);
/* Start the counter */
BM3803_TIM_SETMODE(oneshot->tch, BM3803_TIM_MODE_DOWN);
/* Enable interrupts. We should get the callback when the interrupt
* occurs.
*/
oneshot->running = true;
leave_critical_section(flags);
return OK;
}
/****************************************************************************
* Name: bm3803_oneshot_cancel
*
* Description:
* Cancel the oneshot timer and return the time remaining on the timer.
*
* NOTE: This function may execute at a high rate with no timer running (as
* when pre-emption is enabled and disabled).
*
* Input Parameters:
* oneshot Caller allocated instance of the oneshot state structure. This
* structure must have been previously initialized via a call to
* bm3803_oneshot_initialize();
* ts The location in which to return the time remaining on the
* oneshot timer. A time of zero is returned if the timer is
* not running. 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.
*
****************************************************************************/
int bm3803_oneshot_cancel(struct bm3803_oneshot_s *oneshot,
struct timespec *ts)
{
irqstate_t flags;
uint64_t usec;
uint64_t sec;
uint64_t nsec;
uint32_t count;
uint32_t period;
/* 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 period 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 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 = BM3803_TIM_GETCOUNTER(oneshot->tch);
period = oneshot->period;
/* Now we can disable the interrupt and stop the timer. */
BM3803_TIM_SETISR(oneshot->tch, NULL, NULL, 0);
BM3803_TIM_SETMODE(oneshot->tch, BM3803_TIM_MODE_DISABLED);
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("period=%lu count=%lu\n",
(unsigned long)period, (unsigned long)count);
/* 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 >= period)
{
/* 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)count) * USEC_PER_SEC) /
oneshot->frequency;
/* 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;
}
#endif /* CONFIG_BM3803_ONESHOT */