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RIOT/cpu/lpc2387/periph/timer.c 4.54 KB
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  /*
   * Copyright (C) 2015 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_lpc2387
   * @ingroup     drivers_periph_timer
   * @{
   *
   * @file
   * @brief       Implementation of the low-level timer driver for the LPC2387
   *
   * @author      Hauke Petersen <hauke.petersen@fu-berlin.de>
   * @}
   */
  
  #include <stdint.h>
  #include <string.h>
  
  #include "periph_conf.h"
  #include "periph_cpu.h"
  #include "periph/timer.h"
  
  /**
   * @brief   Check the board config to make sure we do not exceed max number of
   *          timers
   */
  #if TIMER_NUMOF > 3
  #error "ERROR in timer configuration: too many timers defined"
  #endif
  
  /**
   * @brief   Interrupt context information for configured timers
   */
  static timer_isr_ctx_t isr_ctx[TIMER_NUMOF];
  
  /**
   * @brief   Forward declarations for interrupt functions
   * @{
   */
  void tim_isr_0(void);
  void tim_isr_1(void);
  void tim_isr_2(void);
  void tim_isr_3(void);
  /** @} */
  
  /**
   * @brief   Get the base pointer of a timer
   */
  static inline lpc23xx_timer_t *get_dev(tim_t tim)
  {
      switch (tim) {
          case 0:
              return TMR0;
  #if TIMER_NUMOF > 1
          case 1:
              return TMR1;
  #endif
  #if TIMER_NUMOF > 2
          case 2:
              return TMR2;
  #endif
  #if TIMER_NUMOF > 3
          case 3:
              return TMR3;
  #endif
          default:
              return NULL;
      }
  }
  
  static inline void pwr_clk_and_isr(tim_t tim)
  {
      switch (tim) {
          case 0:
              PCONP |= (1 << 1);
              PCLKSEL0 &= ~(0x03 << 2);
              PCLKSEL0 |=  (0x01 << 2);
              install_irq(TIMER0_INT, &tim_isr_0, 1);
              break;
  #if TIMER_NUMOF > 1
          case 1:
              PCONP |= (1 << 2);
              PCLKSEL0 &= ~(0x03 << 4);
              PCLKSEL0 |=  (0x01 << 4);
              install_irq(TIMER1_INT, &tim_isr_1, 1);
              break;
  #endif
  #if TIMER_NUMOF > 2
          case 2:
              PCONP |= (1 << 22);
              PCLKSEL1 &= ~(0x03 << 12);
              PCLKSEL1 |=  (0x01 << 12);
              install_irq(TIMER2_INT, &tim_isr_2, 1);
              break;
  #endif
  #if TIMER_NUMOF > 3
          case 3:
              PCONP |= (1 << 23);
              PCLKSEL1 &= ~(0x03 << 14);
              PCLKSEL1 |=  (0x01 << 14);
              install_irq(TIMER3_INT, &tim_isr_3, 1);
              break;
  #endif
      }
  }
  
  int timer_init(tim_t tim, unsigned long freq, timer_cb_t cb, void *arg)
  {
      /* get the timers base register */
      lpc23xx_timer_t *dev = get_dev(tim);
  
      /* make sure the timer device is valid */
      if (dev == NULL) {
          return -1;
      }
  
      /* save the callback */
      isr_ctx[tim].cb = cb;
      isr_ctx[tim].arg = arg;
      /* enable power, config periph clock and install ISR vector */
      pwr_clk_and_isr(tim);
      /* reset timer configuration (sets the timer to timer mode) */
      dev->TCR = 0;
      dev->CTCR = 0;
      /* configure the prescaler */
      dev->PR = (CLOCK_PCLK / freq) - 1;
      /* enable timer */
      dev->TCR = 1;
      return 0;
  }
  
  int timer_set_absolute(tim_t tim, int channel, unsigned int value)
  {
      if (((unsigned) tim >= TIMER_NUMOF) || ((unsigned) channel >= TIMER_CHAN_NUMOF)) {
          return -1;
      }
  
      lpc23xx_timer_t *dev = get_dev(tim);
      dev->MR[channel] = value;
      dev->MCR |= (1 << (channel * 3));
      return 0;
  }
  
  int timer_clear(tim_t tim, int channel)
  {
      if (((unsigned) tim >= TIMER_NUMOF) || ((unsigned) channel >= TIMER_CHAN_NUMOF)) {
          return -1;
      }
      get_dev(tim)->MCR &= ~(1 << (channel * 3));
      return 0;
  }
  
  unsigned int timer_read(tim_t tim)
  {
      return (unsigned int)(get_dev(tim)->TC);
  }
  
  void timer_start(tim_t tim)
  {
      get_dev(tim)->TCR = 1;
  }
  
  void timer_stop(tim_t tim)
  {
      get_dev(tim)->TCR = 0;
  }
  
  static inline void isr_handler(lpc23xx_timer_t *dev, int tim_num)
  {
      for (unsigned i = 0; i < TIMER_CHAN_NUMOF; i++) {
          if (dev->IR & (1 << i)) {
              dev->IR |= (1 << i);
              dev->MCR &= ~(1 << (i * 3));
              isr_ctx[tim_num].cb(isr_ctx[tim_num].arg, i);
          }
      }
      /* we must not forget to acknowledge the handling of the interrupt */
      VICVectAddr = 0;
  }
  
  void __attribute__((interrupt("IRQ"))) tim_isr_0(void)
  {
      isr_handler(TMR0, 0);
  }
  
  #if TIMER_NUMOF > 1
  void __attribute__((interrupt("IRQ"))) tim_isr_1(void)
  {
      isr_handler(TMR1, 1);
  }
  #endif
  
  #if TIMER_NUMOF > 2
  void __attribute__((interrupt("IRQ"))) tim_isr_2(void)
  {
      isr_handler(TMR2, 2);
  }
  #endif
  
  #if TIMER_NUMOF > 3
  void __attribute__((interrupt("IRQ"))) tim_isr_3(void)
  {
      isr_handler(TMR3, 3);
  }
  #endif