#include	"u.h"
#include	"lib.h"
#include	"mem.h"
#include	"dat.h"
#include	"fns.h"

/*
 *  headland chip set for the safari.
 */

enum
{
	Head=		0x92,		/* control port */
	 Reset=		(1<<0),		/* reset the 386 */
	 A20ena=	(1<<1),		/* enable address line 20 */
};

/*
 *  state of a dma transfer
 */
typedef struct DMAxfer	DMAxfer;
struct DMAxfer
{
	Page	pg;		/* page used by dma */
	void	*va;		/* virtual address destination/src */
	long	len;		/* bytes to be transferred */
	int	isread;
};

/*
 *  the dma controllers.  the first half of this structure specifies
 *  the I/O ports used by the DMA controllers.
 */
typedef struct DMAport	DMAport;
struct DMAport
{
	uchar	addr[4];	/* current address (4 channels) */
	uchar	count[4];	/* current count (4 channels) */
	uchar	page[4];	/* page registers (4 channels) */
	uchar	cmd;		/* command status register */
	uchar	req;		/* request registers */
	uchar	sbm;		/* single bit mask register */
	uchar	mode;		/* mode register */
	uchar	cbp;		/* clear byte pointer */
	uchar	mc;		/* master clear */
	uchar	cmask;		/* clear mask register */
	uchar	wam;		/* write all mask register bit */

	Lock;
};

typdef struct DMA	DMA;
struct DMA
{
	DMAport;
	Lock;
	DMAxfer	x[4];
};

DMA dma[2] = {
	{ 0x00, 0x02, 0x04, 0x06,
	  0x01, 0x03, 0x05, 0x07,
	  0x87, 0x83, 0x81, 0x82,
	  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
	{ 0xc0, 0xc6, 0xca, 0xce,
	  0xc4, 0xc8, 0xcc, 0xcf,
	  0x80, 0x8b, 0x89, 0x8a,
	  0xd0, 0xd2, 0xd4, 0xd6, 0xd8, 0xda, 0xdc, 0xde },
};

/*
 *  enable address bit 20
 */
void
a20enable(void)
{
	outb(Head, A20ena);
}

/*
 *  reset the chip
 */
void
exit(void)
{
	int i;

	u = 0;
	print("exiting\n");
	outb(Head, Reset);
}

/*
 *  setup a dma transfer.  if the destination is not in kernel
 *  memory, allocate a page for the transfer.
 *
 *  we assume BIOS has set up the command register before we
 *  are booted.
 */
long
dmasetup(int chan, void *va, long len, int isread)
{
	DMA *dp;
	DMAxfer *xp;
	ulong pa;
	uchar mode;

	dp = &dma[(chan>>2)&1];
	chan &= 3;
	xp = &dp->x[chan];

	/*
	 *  if this isn't kernel memory, we can't count on it being
	 *  there during the DMA.  Allocate a page for the DMA.
	 */
	if(isphys(va)){
		pa = va & ~KZERO;
	} else {
		xp->pg = newpage(1, 0, 0);
		if(len > BY2PG)
			len = BY2PG;
		if(!isread)
			memmove(KZERO|xp->pg->pa, a, len);
		xp->va = va;
		xp->len = len;
		xp->isread = isread;
		pa = xp->pg->pa;
	}

	/*
	 * this setup must be atomic
	 */
	lock(dp);
	outb(dp->cbp, 0);		/* set count & address to their first byte */
	mode = (isread ? 0x44 : 0x48) | chan;
	outb(dp->mode, mode);		/* single mode dma (give CPU a chance at mem) */
	outb(dp->addr, pa);		/* set address */
	outb(dp->addr, pa>>8);
	outb(dp->page, pa>>16);
	outb(dp->count, len-1);		/* set count */
	outb(dp->count, (len-1)>>8);
	outb(dp->sbm, chan);		/* enable the channel */
	unlock(dp);

	return n;
}

/*
 *  this must be called after a dma has been completed.
 *
 *  if a page has been allocated for the dma,
 *  copy the data into the actual destination
 *  and free the page.
 */
void
dmaend(int chan)
{
	DMA *dp;
	DMAxfer *xp;
	ulong addr;
	uchar mode;

	dp = &dma[(chan>>2)&1];
	chan &= 3;
	outb(dp->sbm, 4|chan);		/* disable the channel */
	xp = &dp->x[chan];
	if(xp->pg == 0)
		return;

	memmove(a, KZERO|xp->pg->pa, xp->len);
	putpage(xp->pg);
	xp->pg = 0;
}