void dma_stream_reset(u32 dma, u8 stream)
{
/* Disable stream (must be done before register is otherwise changed). */
DMA_SCR(dma, stream) &= ~DMA_SxCR_EN;
/* Reset all config bits. */
DMA_SCR(dma, stream) = 0;
/* Reset data transfer number. */
DMA_SNDTR(dma, stream) = 0;
/* Reset peripheral and memory addresses. */
DMA_SPAR(dma, stream) = 0;
DMA_SM0AR(dma, stream) = 0;
DMA_SM1AR(dma, stream) = 0;
/* This is the default setting */
DMA_SFCR(dma, stream) = 0x21;
/* Reset all stream interrupt flags using the interrupt flag clear register. */
u32 mask = DMA_ISR_MASK(stream);
if (stream < 4)
{
DMA_LIFCR(dma) |= mask;
}
else
{
DMA_HIFCR(dma) |= mask;
}
}
/** Setup the USART for transmission with DMA.
* This function sets up the DMA controller and additional USART parameters for
* DMA transmit. The USART must already be configured for normal operation.
*
* \param s The USART DMA state structure.
* \oaram usart The USART base address.
* \param dma The DMA controller base address.
* \param stream The DMA stream number to use.
* \param channel The DMA channel to use. The stream and channel must
* correspond to a USART RX channel.
*/
void usart_tx_dma_setup(usart_tx_dma_state* s, u32 usart,
u32 dma, u8 stream, u8 channel)
{
s->dma = dma;
s->usart = usart;
s->stream = stream;
s->channel = channel;
s->byte_counter = 0;
s->last_byte_ticks = chTimeNow();
/* Enable clock to DMA peripheral. */
if (dma == DMA1)
RCC_AHB1ENR |= RCC_AHB1ENR_DMA1EN;
else if (dma == DMA2)
RCC_AHB1ENR |= RCC_AHB1ENR_DMA2EN;
/* Enable TX DMA on the USART. */
usart_enable_tx_dma(usart);
/* Make sure stream is disabled to start. */
DMA_SCR(dma, stream) &= ~DMA_SxCR_EN;
/* Configure the DMA controller. */
DMA_SCR(dma, stream) = 0;
DMA_SCR(dma, stream) =
/* Error interrupts. */
DMA_SxCR_DMEIE | DMA_SxCR_TEIE |
/* Transfer complete interrupt. */
DMA_SxCR_TCIE |
DMA_SxCR_DIR_MEM_TO_PERIPHERAL |
/* Increment the memory address after each transfer. */
DMA_SxCR_MINC |
/* 4 bytes written to the FIFO from memory at a time */
DMA_SxCR_MBURST_INCR4 |
/* 8 bit transfers from USART peripheral. */
DMA_SxCR_PSIZE_8BIT |
/* and to memory. */
DMA_SxCR_MSIZE_8BIT |
/* TODO: what priority level is necessary? */
/* Very high priority. */
DMA_SxCR_PL_VERY_HIGH |
/* The channel selects which request line will trigger a transfer.
* (see CD00225773.pdf Table 23). */
DMA_SxCR_CHSEL(channel);
/* For now, don't transfer any number of datas
* (will be set in the initiating function). */
DMA_SNDTR(dma, stream) = 0;
/* DMA into the USART data register... */
DMA_SPAR(dma, stream) = &USART_DR(usart);
/* ...from the TX buffer. */
DMA_SM0AR(dma, stream) = s->buff;
/* TODO: Investigate more about the best FIFO settings. */
DMA_SFCR(dma, stream) =
DMA_SxFCR_DMDIS | /* Enable DMA stream FIFO. */
DMA_SxFCR_FTH_2_4_FULL | /* Trigger level 2/4 full. */
DMA_SxFCR_FEIE; /* Enable FIFO error interrupt. */
s->wr = s->rd = 0; /* Buffer is empty to begin with. */
/* Enable DMA interrupts for this stream with the NVIC. */
if (dma == DMA1)
nvicEnableVector(dma_irq_lookup[0][stream],
CORTEX_PRIORITY_MASK(USART_DMA_ISR_PRIORITY));
else if (dma == DMA2)
nvicEnableVector(dma_irq_lookup[1][stream],
CORTEX_PRIORITY_MASK(USART_DMA_ISR_PRIORITY));
}
void dma_set_fifo_threshold(u32 dma, u8 stream, u32 threshold)
{
u32 reg32 = (DMA_SFCR(dma, stream) & ~DMA_SxFCR_FTH_MASK);
DMA_SFCR(dma, stream) = (reg32 | threshold);
}
void dma_enable_fifo_mode(u32 dma, u8 stream)
{
DMA_SFCR(dma, stream) |= DMA_SxFCR_DMDIS;
}
void dma_enable_direct_mode(u32 dma, u8 stream)
{
DMA_SFCR(dma, stream) &= ~DMA_SxFCR_DMDIS;
}
u32 dma_fifo_status(u32 dma, u8 stream)
{
return (DMA_SFCR(dma, stream) & DMA_SxFCR_FS_MASK);
}
void dma_disable_fifo_error_interrupt(u32 dma, u8 stream)
{
DMA_SFCR(dma, stream) &= ~DMA_SxFCR_FEIE;
}
void dma_enable_fifo_error_interrupt(u32 dma, u8 stream)
{
dma_clear_interrupt_flags(dma, stream, DMA_ISR_FEIF);
DMA_SFCR(dma, stream) |= DMA_SxFCR_FEIE;
}