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RIOT/cpu/saml21/periph/timer.c 5.12 KB
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  /*
   * Copyright (C) 2015 Kaspar Schleiser <kaspar@schleiser.de>
   *               2015 FreshTemp, LLC.
   *               2014 Freie Universitรคt Berlin
   *
   *
   * This file is subject to the terms and conditions of the GNU Lesser
   * General Public License v2.1. See the file LICENSE in the top level
   * directory for more details.
   */
  
  /**
   * @ingroup     cpu_saml21
   * @ingroup     drivers_periph_timer
   * @{
   *
   * @file        timer.c
   * @brief       Low-level timer driver implementation
   *
   * @author      Thomas Eichinger <thomas.eichinger@fu-berlin.de>
   * @author      Kaspar Schleiser <kaspar@schleiser.de>
   *
   * @}
   */
  
  #include <stdlib.h>
  #include <stdio.h>
  
  #include "board.h"
  #include "cpu.h"
  
  #include "periph/timer.h"
  #include "periph_conf.h"
  
  #define ENABLE_DEBUG    (0)
  #include "debug.h"
  
  /**
   * @brief Timer state memory
   */
  static timer_isr_ctx_t config[TIMER_NUMOF];
  
  /* enable timer interrupts */
  static inline void _irq_enable(tim_t dev);
  
  /**
   * @brief Setup the given timer
   */
  int timer_init(tim_t dev, unsigned long freq, timer_cb_t cb, void *arg)
  {
      /* configure GCLK0 to feed TC0 & TC1*/;
      GCLK->PCHCTRL[TC0_GCLK_ID].reg |= GCLK_PCHCTRL_CHEN | GCLK_PCHCTRL_GEN_GCLK0;
      while (!(GCLK->PCHCTRL[TC0_GCLK_ID].reg & GCLK_PCHCTRL_CHEN)) {}
  
      /* select the timer and enable the timer specific peripheral clocks */
      switch (dev) {
  #if TIMER_0_EN
      case TIMER_0:
          if (TIMER_0_DEV.CTRLA.bit.ENABLE) {
              return 0;
          }
          MCLK->APBCMASK.reg |= MCLK_APBCMASK_TC0;
          /* reset timer */
          TIMER_0_DEV.CTRLA.bit.SWRST = 1;
          while (TIMER_0_DEV.SYNCBUSY.bit.SWRST) {}
          TIMER_0_DEV.CTRLA.reg |= TC_CTRLA_MODE_COUNT32 |    /* choosing 32 bit mode */
                                   TC_CTRLA_PRESCALER(4) |    /* sourced by 4MHz with Presc 4 results in 1MHz*/
                                   TC_CTRLA_PRESCSYNC_RESYNC; /* initial prescaler resync */
          break;
  #endif
      case TIMER_UNDEFINED:
      default:
          return -1;
      }
  
      /* save callback */
      config[dev].cb = cb;
      config[dev].arg = arg;
  
      /* enable interrupts for given timer */
      _irq_enable(dev);
  
      timer_start(dev);
  
      return 0;
  }
  
  int timer_set_absolute(tim_t dev, int channel, unsigned int value)
  {
      DEBUG("Setting timer %i channel %i to %i\n", dev, channel, value);
  
      /* get timer base register address */
      switch (dev) {
  #if TIMER_0_EN
      case TIMER_0:
          /* set timeout value */
          switch (channel) {
          case 0:
              TIMER_0_DEV.INTFLAG.reg |= TC_INTFLAG_MC0;
              TIMER_0_DEV.CC[0].reg = value;
              TIMER_0_DEV.INTENSET.bit.MC0 = 1;
              break;
          case 1:
              TIMER_0_DEV.INTFLAG.reg |= TC_INTFLAG_MC1;
              TIMER_0_DEV.CC[1].reg = value;
              TIMER_0_DEV.INTENSET.bit.MC1 = 1;
              break;
          default:
              return -1;
          }
          break;
  #endif
      case TIMER_UNDEFINED:
      default:
          return -1;
      }
  
      return 1;
  }
  
  int timer_clear(tim_t dev, int channel)
  {
      /* get timer base register address */
      switch (dev) {
  #if TIMER_0_EN
      case TIMER_0:
          switch (channel) {
          case 0:
              TIMER_0_DEV.INTFLAG.reg |= TC_INTFLAG_MC0;
              TIMER_0_DEV.INTENCLR.bit.MC0 = 1;
              break;
          case 1:
              TIMER_0_DEV.INTFLAG.reg |= TC_INTFLAG_MC1;
              TIMER_0_DEV.INTENCLR.bit.MC1 = 1;
              break;
          default:
              return -1;
          }
          break;
  #endif
      case TIMER_UNDEFINED:
      default:
          return -1;
      }
  
      return 1;
  }
  
  unsigned int timer_read(tim_t dev)
  {
      switch (dev) {
  #if TIMER_0_EN
      case TIMER_0:
          /* request syncronisation */
          TIMER_0_DEV.CTRLBSET.bit.CMD = TC_CTRLBSET_CMD_READSYNC_Val;
          while (TIMER_0_DEV.SYNCBUSY.bit.STATUS) {}
          return TIMER_0_DEV.COUNT.reg;
  #endif
      default:
          return 0;
      }
  
  
  }
  
  void timer_stop(tim_t dev)
  {
      switch (dev) {
  #if TIMER_0_EN
          case TIMER_0:
              TIMER_0_DEV.CTRLA.bit.ENABLE = 0;
              break;
  #endif
          case TIMER_UNDEFINED:
              break;
      }
  }
  
  void timer_start(tim_t dev)
  {
      switch (dev) {
  #if TIMER_0_EN
          case TIMER_0:
              TIMER_0_DEV.CTRLA.bit.ENABLE = 1;
              break;
  #endif
          case TIMER_UNDEFINED:
              break;
      }
  }
  
  static inline void _irq_enable(tim_t dev)
  {
      switch (dev) {
  #if TIMER_0_EN
          case TIMER_0:
              NVIC_EnableIRQ(TC0_IRQn);
              break;
  #endif
          case TIMER_UNDEFINED:
              break;
      }
  }
  
  #if TIMER_0_EN
  void TIMER_0_ISR(void)
  {
      if (TIMER_0_DEV.INTFLAG.bit.MC0 && TIMER_0_DEV.INTENSET.bit.MC0) {
          if(config[TIMER_0].cb) {
              TIMER_0_DEV.INTFLAG.reg |= TC_INTFLAG_MC0;
              TIMER_0_DEV.INTENCLR.reg = TC_INTENCLR_MC0;
              config[TIMER_0].cb(config[TIMER_0].arg, 0);
          }
      }
      else if (TIMER_0_DEV.INTFLAG.bit.MC1 && TIMER_0_DEV.INTENSET.bit.MC1) {
          if(config[TIMER_0].cb) {
              TIMER_0_DEV.INTFLAG.reg |= TC_INTFLAG_MC1;
              TIMER_0_DEV.INTENCLR.reg = TC_INTENCLR_MC1;
              config[TIMER_0].cb(config[TIMER_0].arg, 1);
          }
      }
      cortexm_isr_end();
  }
  #endif /* TIMER_0_EN */