dma.c

伟大的Contiki工程, 短小精悍 的操作系统, 学习编程不可不看

/*
 * Copyright (c) 2007, Swedish Institute of Computer Science
 * All rights reserved.
 *
 * 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 name of the Institute 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 INSTITUTE 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 INSTITUTE 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.
 *
 * This file is part of the Contiki operating system.
 *
 */

/**
 * \file
 *	DMA interrupt handling.
 * \author
 * 	Nicolas Tsiftes <[e-mail]>
 */

#include <io.h>
#include <signal.h>

#include "contiki-msb430.h"
#include "dev/cc1020.h"
#include "dev/dma.h"

static struct process *subscribers[DMA_LINES];
process_event_t dma_event;

interrupt(DACDMA_VECTOR) irq_dacdma(void)
{
  if (DMA0CTL & DMAIFG) {
    DMA0CTL &= ~(DMAIFG | DMAIE);
    if (subscribers[0] != NULL) {
      process_post(subscribers[0], dma_event, NULL);
    }
    LPM_AWAKE();
  }

  if (DMA1CTL & DMAIFG) {
    DMA1CTL &= ~(DMAIFG | DMAIE);
    if (subscribers[1] != NULL) {
      process_post(subscribers[1], dma_event, NULL);
    }
    LPM_AWAKE();
  }

  if (DMA2CTL & DMAIFG) {
    DMA2CTL &= ~(DMAIFG | DMAIE);
    if (subscribers[2] != NULL) {
      process_post(subscribers[2], dma_event, NULL);
    }
    LPM_AWAKE();
  }

  if (DAC12_0CTL & DAC12IFG) {
    DAC12_0CTL &= ~(DAC12IFG | DAC12IE);
  }

  if (DAC12_1CTL & DAC12IFG) {
    DAC12_1CTL &= ~(DAC12IFG | DAC12IE);
  }
}

void
dma_init(void)
{
  dma_event = process_alloc_event();
}

int
dma_subscribe(int line, struct process *p)
{
  if (line >= DMA_LINES)
    return -1;

  subscribers[line] = p;
  return 0;
}

void
dma_transfer(unsigned char *dst, unsigned char *src, unsigned len)
{
  // Configure DMA Channel 0 for UART0 TXIFG.
  DMACTL0 = DMA0TSEL_4;

  // No DMAONFETCH, ROUNDROBIN, ENNMI.
  DMACTL1 = 0x0000;

  /*
   * Set single transfer mode with byte-per-byte transfers.
   *
   * The source address is incremented for each byte, while the 
   * destination address remains constant.
   *
   * In order to avoid missing the first rising edge of the trigger
   * signal, it is important to use the level-sensitive trigger when 
   * using USART transfer interrupts.
   */
  DMA0CTL = DMADT_0 | DMADSTINCR_0 | DMASRCINCR_3 | DMASBDB | DMALEVEL;

  DMA0SA = (unsigned) src;
  DMA0DA = (unsigned) dst;
  DMA0SZ = len;

  DMA0CTL |= DMAEN | DMAIE;	// enable DMA and interrupts
  U0CTL &= ~SWRST;		// enable UART state machine, starts transfer
}