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/**
* @file
*
* @ingroup lpc24xx
*
* @brief DMA support.
*/
/*
* Copyright (c) 2008
* Embedded Brains GmbH
* Obere Lagerstr. 30
* D-82178 Puchheim
* Germany
* rtems@embedded-brains.de
*
* The license and distribution terms for this file may be found in the file
* LICENSE in this distribution or at http://www.rtems.com/license/LICENSE.
*/
#include <rtems/endian.h>
#include <bsp/lpc24xx.h>
#include <bsp/dma.h>
/**
* @brief Table that indicates if a channel is currently occupied.
*/
static bool lpc24xx_dma_channel_occupation [GPDMA_CH_NUMBER];
/**
* @brief Initializes the general purpose DMA.
*/
void lpc24xx_dma_initialize( void)
{
rtems_interrupt_level level;
/* Enable power */
rtems_interrupt_disable( level);
PCONP = SET_FLAG( PCONP, PCONP_PCGPDMA);
rtems_interrupt_enable( level);
/* Disable module */
GPDMA_CONFIG = 0;
/* Enable module */
#if BYTE_ORDER == LITTLE_ENDIAN
GPDMA_CONFIG = GPDMA_CONFIG_EN;
#else
GPDMA_CONFIG = GPDMA_CONFIG_EN | GPDMA_CONFIG_MODE;
#endif
/* Reset registers */
GPDMA_SOFT_SREQ = 0;
GPDMA_SOFT_BREQ = 0;
GPDMA_SOFT_LSREQ = 0;
GPDMA_SOFT_LBREQ = 0;
GPDMA_SYNC = 0;
}
/**
* @brief Returns true if the channel @a channel was obtained.
*
* If the channel number @a channel is out of range the last valid channel will
* be used.
*/
bool lpc24xx_dma_channel_obtain( unsigned channel)
{
rtems_interrupt_level level;
bool occupation = true;
if (channel > GPDMA_CH_NUMBER) {
channel = GPDMA_CH_NUMBER - 1;
}
rtems_interrupt_disable( level);
occupation = lpc24xx_dma_channel_occupation [channel];
lpc24xx_dma_channel_occupation [channel] = true;
rtems_interrupt_enable( level);
return !occupation;
}
/**
* @brief Releases the channel @a channel. You must have obtained this channel
* with lpc24xx_dma_channel_obtain() previously.
*
* If the channel number @a channel is out of range the last valid channel will
* be used.
*/
void lpc24xx_dma_channel_release( unsigned channel)
{
if (channel > GPDMA_CH_NUMBER) {
channel = GPDMA_CH_NUMBER - 1;
}
lpc24xx_dma_channel_occupation [channel] = false;
}
/**
* @brief Disables the channel @a channel.
*
* If @a force is false the channel will be halted and disabled when the
* channel is inactive. If the channel number @a channel is out of range the
* last valid channel will be used.
*/
void lpc24xx_dma_channel_disable( unsigned channel, bool force)
{
volatile lpc24xx_dma_channel *ch = GPDMA_CH_BASE_ADDR( channel);
uint32_t cfg = ch->cfg;
if (!force) {
/* Halt */
ch->cfg = SET_FLAG( cfg, GPDMA_CH_CFG_HALT);
/* Wait for inactive */
do {
cfg = ch->cfg;
} while (IS_FLAG_SET( cfg, GPDMA_CH_CFG_ACTIVE));
}
/* Disable */
ch->cfg = CLEAR_FLAG( cfg, GPDMA_CH_CFG_EN);
}
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