dma.c

#include <stdint.h>
#include <stddef.h>

#include "dma.h"

#define DMA_BASE   0x20007000
#define DMA_ENABLE 0x20007FF0

#define DMA_CS_OFFSET        0x00
#define DMA_CONBLK_AD_OFFSET 0x01

#define DMA_PTR(channel, offset) (((volatile uint32_t*)DMA_BASE) + ((channel) << 6) + (offset))

struct DMAControlBlock
{
    uint32_t transferInfo;
    uint32_t srcAddress;
    uint32_t dstAddress;
    uint32_t transferLen;
    uint32_t stride;
    struct DMAControlBlock *next;
};

static void DMALaunchRequest(uint8_t channel, const struct DMAControlBlock *controlBlock)
{
    *(uint32_t*)DMA_ENABLE = 1; // Enable DMA channel 0
    
    // Wait for channel being inactive
    while((*DMA_PTR(channel, DMA_CS_OFFSET)) & 1);
    
    *DMA_PTR(channel, DMA_CONBLK_AD_OFFSET) = 0x40000000 | (uint32_t) controlBlock;
    *DMA_PTR(channel, DMA_CS_OFFSET) = 7; // Enables DMA transfer
}

void DMACopy32(void *dst, void *src, size_t sizeBytes)
{
    static struct DMAControlBlock __attribute__((aligned(0x100))) controlBlock;

    controlBlock.transferInfo = (0 << 9)  // 32 bit source read
                              | (1 << 8)  // Increment source
                              | (0 << 5)  // 32 bit destination write
                              | (1 << 4); // Increment destination
    controlBlock.srcAddress = 0x40000000 | (uint32_t) src;
    controlBlock.dstAddress = 0x40000000 | (uint32_t) dst;
    controlBlock.transferLen = sizeBytes;
    controlBlock.stride = 0;
    controlBlock.next = 0; // No chained operation

    DMALaunchRequest(0, &controlBlock);
}