linux/include/asm-x86/mca_dma.h

#ifndef MCA_DMA_H
#define MCA_DMA_H

#include <asm/io.h>
#include <linux/ioport.h>

/*
 * Microchannel specific DMA stuff.  DMA on an MCA machine is fairly similar to
 *   standard PC dma, but it certainly has its quirks.  DMA register addresses
 *   are in a different place and there are some added functions.  Most of this
 *   should be pretty obvious on inspection.  Note that the user must divide
 *   count by 2 when using 16-bit dma; that is not handled by these functions.
 *
 * Ramen Noodles are yummy.
 * 
 *  1998 Tymm Twillman <tymm@computer.org>  
 */

/*
 * Registers that are used by the DMA controller; FN is the function register 
 *   (tell the controller what to do) and EXE is the execution register (how
 *   to do it)
 */

#define MCA_DMA_REG_FN  0x18
#define MCA_DMA_REG_EXE 0x1A 

/*
 * Functions that the DMA controller can do
 */

#define MCA_DMA_FN_SET_IO       0x00
#define MCA_DMA_FN_SET_ADDR     0x20
#define MCA_DMA_FN_GET_ADDR     0x30
#define MCA_DMA_FN_SET_COUNT    0x40
#define MCA_DMA_FN_GET_COUNT    0x50
#define MCA_DMA_FN_GET_STATUS   0x60
#define MCA_DMA_FN_SET_MODE     0x70
#define MCA_DMA_FN_SET_ARBUS    0x80
#define MCA_DMA_FN_MASK         0x90
#define MCA_DMA_FN_RESET_MASK   0xA0
#define MCA_DMA_FN_MASTER_CLEAR 0xD0

/*
 * Modes (used by setting MCA_DMA_FN_MODE in the function register)
 * 
 * Note that the MODE_READ is read from memory (write to device), and
 *   MODE_WRITE is vice-versa.  
 */

#define MCA_DMA_MODE_XFER  0x04  /* read by default */
#define MCA_DMA_MODE_READ  0x04  /* same as XFER */
#define MCA_DMA_MODE_WRITE 0x08  /* OR with MODE_XFER to use */
#define MCA_DMA_MODE_IO    0x01  /* DMA from IO register */
#define MCA_DMA_MODE_16    0x40  /* 16 bit xfers */


/**
 *	mca_enable_dma	-	channel to enable DMA on
 *	@dmanr: DMA channel
 *
 *	Enable the MCA bus DMA on a channel. This can be called from
 *	IRQ context.
 */

static __inline__ void mca_enable_dma(unsigned int dmanr)
{
	outb(MCA_DMA_FN_RESET_MASK | dmanr, MCA_DMA_REG_FN);
}

/**
 *	mca_disble_dma	-	channel to disable DMA on
 *	@dmanr: DMA channel
 *
 *	Enable the MCA bus DMA on a channel. This can be called from
 *	IRQ context.
 */

static __inline__ void mca_disable_dma(unsigned int dmanr)
{
	outb(MCA_DMA_FN_MASK | dmanr, MCA_DMA_REG_FN);
}

/**
 *	mca_set_dma_addr -	load a 24bit DMA address
 *	@dmanr: DMA channel
 *	@a: 24bit bus address
 *
 *	Load the address register in the DMA controller. This has a 24bit
 *	limitation (16Mb). 
 */

static __inline__ void mca_set_dma_addr(unsigned int dmanr, unsigned int a)
{
	outb(MCA_DMA_FN_SET_ADDR | dmanr, MCA_DMA_REG_FN);
	outb(a & 0xff, MCA_DMA_REG_EXE);
	outb((a >> 8) & 0xff, MCA_DMA_REG_EXE);
	outb((a >> 16) & 0xff, MCA_DMA_REG_EXE);
}

/**
 *	mca_get_dma_addr -	load a 24bit DMA address
 *	@dmanr: DMA channel
 *
 *	Read the address register in the DMA controller. This has a 24bit
 *	limitation (16Mb). The return is a bus address.
 */

static __inline__ unsigned int mca_get_dma_addr(unsigned int dmanr)
{
	unsigned int addr;

	outb(MCA_DMA_FN_GET_ADDR | dmanr, MCA_DMA_REG_FN);
	addr = inb(MCA_DMA_REG_EXE);
	addr |= inb(MCA_DMA_REG_EXE) << 8;
	addr |= inb(MCA_DMA_REG_EXE) << 16;  

	return addr;
}

/**
 *	mca_set_dma_count -	load a 16bit transfer count
 *	@dmanr: DMA channel
 *	@count: count
 *
 *	Set the DMA count for this channel. This can be up to 64Kbytes.
 *	Setting a count of zero will not do what you expect.
 */

static __inline__ void mca_set_dma_count(unsigned int dmanr, unsigned int count)
{
	count--;  /* transfers one more than count -- correct for this */

	outb(MCA_DMA_FN_SET_COUNT | dmanr, MCA_DMA_REG_FN);
	outb(count & 0xff, MCA_DMA_REG_EXE);
	outb((count >> 8) & 0xff, MCA_DMA_REG_EXE);
}

/**
 *	mca_get_dma_residue -	get the remaining bytes to transfer
 *	@dmanr: DMA channel
 *
 *	This function returns the number of bytes left to transfer
 *	on this DMA channel.
 */

static __inline__ unsigned int mca_get_dma_residue(unsigned int dmanr)
{
	unsigned short count;

	outb(MCA_DMA_FN_GET_COUNT | dmanr, MCA_DMA_REG_FN);
	count = 1 + inb(MCA_DMA_REG_EXE);
	count += inb(MCA_DMA_REG_EXE) << 8;

	return count;
}

/**
 *	mca_set_dma_io -	set the port for an I/O transfer
 *	@dmanr: DMA channel
 *	@io_addr: an I/O port number
 *
 *	Unlike the ISA bus DMA controllers the DMA on MCA bus can transfer
 *	with an I/O port target.
 */

static __inline__ void mca_set_dma_io(unsigned int dmanr, unsigned int io_addr)
{
	/*
	 * DMA from a port address -- set the io address
	 */
	
	outb(MCA_DMA_FN_SET_IO | dmanr, MCA_DMA_REG_FN);
	outb(io_addr & 0xff, MCA_DMA_REG_EXE);
	outb((io_addr >>  8) & 0xff, MCA_DMA_REG_EXE);
}

/**
 *	mca_set_dma_mode -	set the DMA mode
 *	@dmanr: DMA channel
 *	@mode: mode to set
 *
 *	The DMA controller supports several modes. The mode values you can
 *	set are-
 *
 *	%MCA_DMA_MODE_READ when reading from the DMA device.
 *
 *	%MCA_DMA_MODE_WRITE to writing to the DMA device.
 *
 *	%MCA_DMA_MODE_IO to do DMA to or from an I/O port.
 *
 *	%MCA_DMA_MODE_16 to do 16bit transfers.
 */

static __inline__ void mca_set_dma_mode(unsigned int dmanr, unsigned int mode)
{
	outb(MCA_DMA_FN_SET_MODE | dmanr, MCA_DMA_REG_FN);
	outb(mode, MCA_DMA_REG_EXE);
}

#endif /* MCA_DMA_H */