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/******************************************************************************
* The MIT License
*
* Copyright (c) 2010 Michael Hope.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*****************************************************************************/
/**
* @file dma.c
*
* @brief Direct Memory Access peripheral support
*/
#include "libmaple.h"
#include "dma.h"
#include "rcc.h"
#define DMA_EN BIT(0)
typedef struct dma_regs
{
uint32 CCR;
uint32 CNDTR;
uint32 CPAR;
uint32 CMAR;
} dma_regs;
/** Get the base address of the given channel, asserting and returning
* NULL on illegal
*/
static dma_regs *dma_get_regs(uint8 channel) {
if (channel >= 1 && channel <= 7) {
return (dma_regs *)(DMA1_CCR1 + DMA_CHANNEL_STRIDE * (channel-1));
}
else {
ASSERT(false);
return NULL;
}
}
/** Initialise a DMA channel. Start the transfer using dma_start().
*
* @param channel the channel number (1..7)
* @param peripheral address of the peripheral
* @param from_peripheral true if transfer goes from the peripheral
* to memory
* @param mode OR of the dma_mode_flags
*/
void dma_init(uint8 channel, volatile void *peripheral, int from_peripheral,
dma_mode_flags mode) {
volatile dma_regs *regs = dma_get_regs(channel);
if (regs != NULL) {
rcc_clk_enable(RCC_DMA1);
/* Disable the channel. PENDING: May not be needed */
regs->CCR = 0;
uint32 cr = 0
| (0 << 12) // Low priority
| (0 << 10) // Memory size = 8 bits
| (1 << 8) // Peripheral size = 16 bits
| (mode << 5) // Increment and circular modes
| (0 << 0); // Not enabled
/* FIXME XXX integer from pointer without a cast. */
regs->CPAR = peripheral;
if (!from_peripheral) {
cr |= 1 << 4; // From memory
}
/* Stay disabled until started */
regs->CCR = cr;
}
}
void dma_start(uint8 channel, volatile void *buffer, uint16 count)
{
volatile dma_regs *regs = dma_get_regs(channel);
if (regs != NULL) {
regs->CCR &= ~DMA_EN;
regs->CMAR = (uint32)buffer;
regs->CNDTR = count;
regs->CCR |= DMA_EN;
}
}
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