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/**
* @file
*
* @ingroup lpc24xx
*
* @brief DMA support.
*/
/*
* Copyright (c) 2008, 2009
* 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>
#include <bsp/io.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 module power */
lpc24xx_module_enable(LPC24XX_MODULE_GPDMA, 0, LPC24XX_MODULE_PCLK_DEFAULT);
/* 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 Tries to obtain the channel @a channel.
*
* @retval RTEMS_SUCCESSFUL Successful operation.
* @retval RTEMS_INVALID_ID Invalid channel number.
* @retval RTEMS_RESOURCE_IN_USE Channel already occupied.
*/
rtems_status_code lpc24xx_dma_channel_obtain(unsigned channel)
{
if (channel < GPDMA_CH_NUMBER) {
rtems_interrupt_level level;
bool occupation = true;
rtems_interrupt_disable(level);
occupation = lpc24xx_dma_channel_occupation [channel];
lpc24xx_dma_channel_occupation [channel] = true;
rtems_interrupt_enable(level);
return occupation ? RTEMS_RESOURCE_IN_USE : RTEMS_SUCCESSFUL;
} else {
return RTEMS_INVALID_ID;
}
}
/**
* @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 nothing will happen.
*/
void lpc24xx_dma_channel_release(unsigned channel)
{
if (channel < GPDMA_CH_NUMBER) {
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 behaviour is undefined.
*/
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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