dma.c

nucleus_arm.rar

/*
* DMA access					*
* v0.1: TDS						*
*       - basic routines		*
* v0.2: TDS (26.05.2004)		*
*		- removed floppy hack	*
* v0.3: Doug Gale													*
*		- Disables interrupts while programming DMA controller(s)	*
*/

#include <support.h>
#include <stdio.h>
#include <drivers/pic.h>
#include <interrupts.h>
#include <drivers/dma.h>

/* Just helps in making things look cleaner.  :) */
typedef unsigned char   uchar;
typedef unsigned int    uint;

/* Quick-access registers and ports for each DMA channel. */
static const uchar MaskReg[8]   = { 0x0A, 0x0A, 0x0A, 0x0A, 0xD4, 0xD4, 0xD4, 0xD4 };
static const uchar ModeReg[8]   = { 0x0B, 0x0B, 0x0B, 0x0B, 0xD6, 0xD6, 0xD6, 0xD6 };
static const uchar ClearReg[8]  = { 0x0C, 0x0C, 0x0C, 0x0C, 0xD8, 0xD8, 0xD8, 0xD8 };

static const uchar PagePort[8]  = { 0x87, 0x83, 0x81, 0x82, 0x8F, 0x8B, 0x89, 0x8A };
static const uchar AddrPort[8]  = { 0x00, 0x02, 0x04, 0x06, 0xC0, 0xC4, 0xC8, 0xCC };
static const uchar CountPort[8] = { 0x01, 0x03, 0x05, 0x07, 0xC2, 0xC6, 0xCA, 0xCE };
	
void _dma_xfer(uchar DMA_channel, unsigned char page, unsigned int offset, unsigned int length, uchar mode);


void dma_xfer(uchar channel, unsigned long address, 
		unsigned int length, unsigned char read)
{
	unsigned char page=0, mode=0;
	unsigned int offset = 0;
	
	if (read)
		mode = 0x48 + channel;
	else
		mode = 0x44 + channel;
		
	page = address >> 16;
	offset = address & 0xFFFF;
	length--;
	
	_dma_xfer(channel, page, offset, length, mode);	
}	
		

void _dma_xfer(uchar DMA_channel, unsigned char page, unsigned int offset,
		unsigned int length, uchar mode)
{
    /* Don't let anyone else mess up what we're doing. */
	int ints_were_enabled = interrupts_disable();

    /* Set up the DMA channel so we can use it.  This tells the DMA */
    /* that we're going to be using this channel.  (It's masked) */
    outportb(MaskReg[DMA_channel], 0x04 | DMA_channel);
    
	/* Clear any data transfers that are currently executing. */
    outportb(ClearReg[DMA_channel], 0x00);

    /* Send the offset address.  The first byte is the low base offset, the */
    /* second byte is the high offset. */
    outportb(AddrPort[DMA_channel], LO_BYTE(offset));
    outportb(AddrPort[DMA_channel], HI_BYTE(offset));

	/* Clear any data transfers that are currently executing. */
    outportb(ClearReg[DMA_channel], 0x00);

    /* Send the length of the data.  Again, low byte first. */
    outportb(CountPort[DMA_channel], LO_BYTE(length));
    outportb(CountPort[DMA_channel], HI_BYTE(length));
	
	/* Send the specified mode to the DMA. */
    outportb(ModeReg[DMA_channel], mode);

    /* Send the physical page that the data lies on. */
    outportb(PagePort[DMA_channel], page);

    /* Ok, we're done.  Enable the DMA channel (clear the mask). */
    outportb(MaskReg[DMA_channel], DMA_channel);

    /* Ok, we're done.  Enable the DMA channel (clear the mask). */
    outportb(MaskReg[DMA_channel], DMA_channel);

    /* Re-enable interrupts before we leave. */
	if (ints_were_enabled)
		interrupts_enable();
}