nuttx/arch/arm/src/stm32/stm32_oneshot.c

/****************************************************************************
 * arch/arm/src/stm32/stm32_oneshot.c
 *
 *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the names NuttX nor Atmel nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <sys/types.h>
#include <stdint.h>
#include <stdbool.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>

#include <nuttx/irq.h>
#include <nuttx/clock.h>

#include "stm32_oneshot.h"

#ifdef CONFIG_STM32_ONESHOT

/****************************************************************************
 * Private Date
 ****************************************************************************/

static struct stm32_oneshot_s *g_oneshot;

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: stm32_oneshot_handler
 *
 * Description:
 *   Timer interrupt callback.  When the oneshot timer interrupt expires,
 *   this function will be called.  It will forward the call to the next
 *   level up.
 *
 * Input Parameters:
 *   tch - The handle that represents the timer state
 *   arg - An opaque argument provided when the interrupt was registered
 *   sr  - The value of the timer interrupt status register at the time
 *         that the interrupt occurred.
 *
 * Returned Value:
 *   None
 *
 ****************************************************************************/

static int stm32_oneshot_handler(int irq, void *context)
{
  struct stm32_oneshot_s *oneshot = g_oneshot;
  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.
   */

  STM32_TIM_SETISR(oneshot->tch, NULL, 0);
  STM32_TIM_DISABLEINT(oneshot->tch, 0);
  STM32_TIM_SETMODE(oneshot->tch, STM32_TIM_MODE_DISABLED);
  STM32_TIM_ACKINT(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: stm32_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 stm32_oneshot_initialize(struct stm32_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 = stm32_tim_init(chan);
  if (!oneshot->tch)
    {
      tmrerr("ERROR: Failed to allocate TIM%d\n", chan);
      return -EBUSY;
    }

  STM32_TIM_SETCLOCK(oneshot->tch, frequency);

  /* Initialize the remaining fields in the state structure and return
   * success.
   */

  oneshot->chan       = chan;
  oneshot->running    = false;
  oneshot->handler    = NULL;
  oneshot->arg        = NULL;

  g_oneshot           = oneshot;
  return OK;
}

/****************************************************************************
 * Name: stm32_oneshot_max_delay
 *
 * Description:
 *   Determine the maximum delay of the one-shot timer (in microseconds)
 *
 ****************************************************************************/

int stm32_oneshot_max_delay(struct stm32_oneshot_s *oneshot, uint64_t *usec)
{
  DEBUGASSERT(oneshot != NULL && usec != NULL);

  *usec = (uint64_t)(UINT32_MAX / oneshot->frequency) *
          (uint64_t)USEC_PER_SEC;
  return OK;
}

/****************************************************************************
 * Name: stm32_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
 *           stm32_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 stm32_oneshot_start(struct stm32_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");
      (void)stm32_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 <= UINT32_MAX);

  /* Set up to receive the callback when the interrupt occurs */

  STM32_TIM_SETISR(oneshot->tch, stm32_oneshot_handler, 0);

  /* Set timer period */

  oneshot->period = (uint32_t)period;
  STM32_TIM_SETPERIOD(oneshot->tch, (uint32_t)period);

  /* Start the counter */

  STM32_TIM_SETMODE(oneshot->tch, STM32_TIM_MODE_PULSE);

  STM32_TIM_ACKINT(oneshot->tch, 0);
  STM32_TIM_ENABLEINT(oneshot->tch, 0);

  /* Enable interrupts.  We should get the callback when the interrupt
   * occurs.
   */

  oneshot->running = true;
  leave_critical_section(flags);
  return OK;
}

/****************************************************************************
 * Name: stm32_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
 *           stm32_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 stm32_oneshot_cancel(struct stm32_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 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  = STM32_TIM_GETCOUNTER(oneshot->tch);
  period = oneshot->period;

  /* Now we can disable the interrupt and stop the timer. */

  STM32_TIM_DISABLEINT(oneshot->tch, 0);
  STM32_TIM_SETISR(oneshot->tch, NULL, 0);
  STM32_TIM_SETMODE(oneshot->tch, STM32_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)(period - 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_STM32_ONESHOT */