NetBSD/sys/arch/i386/isa/isa_machdep.c

/*	$NetBSD: isa_machdep.c,v 1.51 2001/01/10 01:15:32 thorpej Exp $	*/

#define ISA_DMA_STATS

/*-
 * Copyright (c) 1996, 1997, 1998 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Charles M. Hannum and by Jason R. Thorpe of the Numerical Aerospace
 * Simulation Facility, NASA Ames Research Center.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the NetBSD
 *	Foundation, Inc. and its contributors.
 * 4. Neither the name of The NetBSD Foundation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*-
 * Copyright (c) 1991 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * William Jolitz.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)isa.c	7.2 (Berkeley) 5/13/91
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/syslog.h>
#include <sys/device.h>
#include <sys/malloc.h>
#include <sys/proc.h>
#include <sys/mbuf.h>

#define _I386_BUS_DMA_PRIVATE
#include <machine/bus.h>

#include <machine/pio.h>
#include <machine/cpufunc.h>

#include <dev/isa/isareg.h>
#include <dev/isa/isavar.h>
#include <i386/isa/icu.h>

#include <uvm/uvm_extern.h>

#include "mca.h"
#if NMCA > 0
#include <machine/mca_machdep.h>		/* for MCA_system */
#endif

/*
 * ISA can only DMA to 0-16M.
 */
#define	ISA_DMA_BOUNCE_THRESHOLD	(16 * 1024 * 1024)

extern	paddr_t avail_end;

#define	IDTVEC(name)	__CONCAT(X,name)
typedef void (vector) __P((void));
extern vector *IDTVEC(intr)[];
void isa_strayintr __P((int));
void intr_calculatemasks __P((void));
static int fakeintr __P((void *));
#if NMCA > 0
static int mca_clockfakeintr __P((void *));
#endif

/*
 * Cookie used by ISA dma.  A pointer to one of these it stashed in
 * the DMA map.
 */
struct i386_isa_dma_cookie {
	int	id_flags;		/* flags; see below */

	/*
	 * Information about the original buffer used during
	 * DMA map syncs.  Note that origibuflen is only used
	 * for ID_BUFTYPE_LINEAR.
	 */
	void	*id_origbuf;		/* pointer to orig buffer if
					   bouncing */
	bus_size_t id_origbuflen;	/* ...and size */
	int	id_buftype;		/* type of buffer */

	void	*id_bouncebuf;		/* pointer to the bounce buffer */
	bus_size_t id_bouncebuflen;	/* ...and size */
	int	id_nbouncesegs;		/* number of valid bounce segs */
	bus_dma_segment_t id_bouncesegs[0]; /* array of bounce buffer
					       physical memory segments */
};

/* id_flags */
#define	ID_MIGHT_NEED_BOUNCE	0x01	/* map could need bounce buffers */
#define	ID_HAS_BOUNCE		0x02	/* map currently has bounce buffers */
#define	ID_IS_BOUNCING		0x04	/* map is bouncing current xfer */

/* id_buftype */
#define	ID_BUFTYPE_INVALID	0
#define	ID_BUFTYPE_LINEAR	1
#define	ID_BUFTYPE_MBUF		2
#define	ID_BUFTYPE_UIO		3
#define	ID_BUFTYPE_RAW		4

int	_isa_bus_dmamap_create __P((bus_dma_tag_t, bus_size_t, int,
	    bus_size_t, bus_size_t, int, bus_dmamap_t *));
void	_isa_bus_dmamap_destroy __P((bus_dma_tag_t, bus_dmamap_t));
int	_isa_bus_dmamap_load __P((bus_dma_tag_t, bus_dmamap_t, void *,
	    bus_size_t, struct proc *, int));
int	_isa_bus_dmamap_load_mbuf __P((bus_dma_tag_t, bus_dmamap_t,
	    struct mbuf *, int));
int	_isa_bus_dmamap_load_uio __P((bus_dma_tag_t, bus_dmamap_t,
	    struct uio *, int));
int	_isa_bus_dmamap_load_raw __P((bus_dma_tag_t, bus_dmamap_t,
	    bus_dma_segment_t *, int, bus_size_t, int));
void	_isa_bus_dmamap_unload __P((bus_dma_tag_t, bus_dmamap_t));
void	_isa_bus_dmamap_sync __P((bus_dma_tag_t, bus_dmamap_t,
	    bus_addr_t, bus_size_t, int));

int	_isa_bus_dmamem_alloc __P((bus_dma_tag_t, bus_size_t, bus_size_t,
	    bus_size_t, bus_dma_segment_t *, int, int *, int));

int	_isa_dma_alloc_bouncebuf __P((bus_dma_tag_t, bus_dmamap_t,
	    bus_size_t, int));
void	_isa_dma_free_bouncebuf __P((bus_dma_tag_t, bus_dmamap_t));

/*
 * Entry points for ISA DMA.  These are mostly wrappers around
 * the generic functions that understand how to deal with bounce
 * buffers, if necessary.
 */
struct i386_bus_dma_tag isa_bus_dma_tag = {
	ISA_DMA_BOUNCE_THRESHOLD,
	_isa_bus_dmamap_create,
	_isa_bus_dmamap_destroy,
	_isa_bus_dmamap_load,
	_isa_bus_dmamap_load_mbuf,
	_isa_bus_dmamap_load_uio,
	_isa_bus_dmamap_load_raw,
	_isa_bus_dmamap_unload,
	_isa_bus_dmamap_sync,
	_isa_bus_dmamem_alloc,
	_bus_dmamem_free,
	_bus_dmamem_map,
	_bus_dmamem_unmap,
	_bus_dmamem_mmap,
};

/*
 * Fill in default interrupt table (in case of spuruious interrupt
 * during configuration of kernel, setup interrupt control unit
 */
void
isa_defaultirq()
{
	int i;

	/* icu vectors */
	for (i = 0; i < ICU_LEN; i++)
		setgate(&idt[ICU_OFFSET + i].gd, IDTVEC(intr)[i], 0,
		    SDT_SYS386IGT, SEL_KPL);
  
	/* initialize 8259's */
#if NMCA > 0
	/* level-triggered interrupts on MCA PS/2s */
	if (MCA_system)
		outb(IO_ICU1, 0x19);	/* reset; program device, four bytes */
	else
#endif
		outb(IO_ICU1, 0x11);	/* reset; program device, four bytes */

	outb(IO_ICU1+1, ICU_OFFSET);	/* starting at this vector index */
	outb(IO_ICU1+1, 1 << IRQ_SLAVE); /* slave on line 2 */
#ifdef AUTO_EOI_1
	outb(IO_ICU1+1, 2 | 1);		/* auto EOI, 8086 mode */
#else
	outb(IO_ICU1+1, 1);		/* 8086 mode */
#endif
	outb(IO_ICU1+1, 0xff);		/* leave interrupts masked */
	outb(IO_ICU1, 0x68);		/* special mask mode (if available) */
	outb(IO_ICU1, 0x0a);		/* Read IRR by default. */
#ifdef REORDER_IRQ
	outb(IO_ICU1, 0xc0 | (3 - 1));	/* pri order 3-7, 0-2 (com2 first) */
#endif

#if NMCA > 0
	/* level-triggered interrupts on MCA PS/2s */
	if (MCA_system)
		outb(IO_ICU2, 0x19);	/* reset; program device, four bytes */
	else
#endif	
		outb(IO_ICU2, 0x11);	/* reset; program device, four bytes */

	outb(IO_ICU2+1, ICU_OFFSET+8);	/* staring at this vector index */
	outb(IO_ICU2+1, IRQ_SLAVE);
#ifdef AUTO_EOI_2
	outb(IO_ICU2+1, 2 | 1);		/* auto EOI, 8086 mode */
#else
	outb(IO_ICU2+1, 1);		/* 8086 mode */
#endif
	outb(IO_ICU2+1, 0xff);		/* leave interrupts masked */
	outb(IO_ICU2, 0x68);		/* special mask mode (if available) */
	outb(IO_ICU2, 0x0a);		/* Read IRR by default. */
}

/*
 * Handle a NMI, possibly a machine check.
 * return true to panic system, false to ignore.
 */
int
isa_nmi()
{
	log(LOG_CRIT, "NMI port 61 %x, port 70 %x\n", inb(0x61), inb(0x70));
	return(0);
}

/*
 * Caught a stray interrupt, notify
 */
void
isa_strayintr(irq)
	int irq;
{
	static u_long strays;

        /*
         * Stray interrupts on irq 7 occur when an interrupt line is raised
         * and then lowered before the CPU acknowledges it.  This generally
         * means either the device is screwed or something is cli'ing too
         * long and it's timing out.
         */
	if (++strays <= 5)
		log(LOG_ERR, "stray interrupt %d%s\n", irq,
		    strays >= 5 ? "; stopped logging" : "");
}

int intrtype[ICU_LEN], intrmask[ICU_LEN], intrlevel[ICU_LEN];
struct intrhand *intrhand[ICU_LEN];

/*
 * Recalculate the interrupt masks from scratch.
 * We could code special registry and deregistry versions of this function that
 * would be faster, but the code would be nastier, and we don't expect this to
 * happen very much anyway.
 */
void
intr_calculatemasks()
{
	int irq, level, unusedirqs;
	struct intrhand *q;

	/* First, figure out which levels each IRQ uses. */
	unusedirqs = 0xffff;
	for (irq = 0; irq < ICU_LEN; irq++) {
		int levels = 0;
		for (q = intrhand[irq]; q; q = q->ih_next)
			levels |= 1 << q->ih_level;
		intrlevel[irq] = levels;
		if (levels)
			unusedirqs &= ~(1 << irq);
	}

	/* Then figure out which IRQs use each level. */
	for (level = 0; level < NIPL; level++) {
		int irqs = 0;
		for (irq = 0; irq < ICU_LEN; irq++)
			if (intrlevel[irq] & (1 << level))
				irqs |= 1 << irq;
		imask[level] = irqs | unusedirqs;
	}

	/*
	 * Initialize soft interrupt masks to block themselves.
	 */
	imask[IPL_SOFTCLOCK] = 1 << SIR_CLOCK;
	imask[IPL_SOFTNET] = 1 << SIR_NET;
	imask[IPL_SOFTSERIAL] = 1 << SIR_SERIAL;

	/*
	 * IPL_NONE is used for hardware interrupts that are never blocked,
	 * and do not block anything else.
	 */
	imask[IPL_NONE] = 0;

	/*
	 * Enforce a hierarchy that gives slow devices a better chance at not
	 * dropping data.
	 */
	imask[IPL_SOFTCLOCK] |= imask[IPL_NONE];
	imask[IPL_SOFTNET] |= imask[IPL_SOFTCLOCK];
	imask[IPL_BIO] |= imask[IPL_SOFTNET];
	imask[IPL_NET] |= imask[IPL_BIO];
	imask[IPL_SOFTSERIAL] |= imask[IPL_NET];
	imask[IPL_TTY] |= imask[IPL_SOFTSERIAL];

	/*
	 * There are tty, network and disk drivers that use free() at interrupt
	 * time, so imp > (tty | net | bio).
	 */
	imask[IPL_IMP] |= imask[IPL_TTY];

	imask[IPL_AUDIO] |= imask[IPL_IMP];

	/*
	 * Since run queues may be manipulated by both the statclock and tty,
	 * network, and disk drivers, clock > imp.
	 */
	imask[IPL_CLOCK] |= imask[IPL_AUDIO];

	/*
	 * IPL_HIGH must block everything that can manipulate a run queue.
	 */
	imask[IPL_HIGH] |= imask[IPL_CLOCK];

	/*
	 * We need serial drivers to run at the absolute highest priority to
	 * avoid overruns, so serial > high.
	 */
	imask[IPL_SERIAL] |= imask[IPL_HIGH];

	/* And eventually calculate the complete masks. */
	for (irq = 0; irq < ICU_LEN; irq++) {
		int irqs = 1 << irq;
		for (q = intrhand[irq]; q; q = q->ih_next)
			irqs |= imask[q->ih_level];
		intrmask[irq] = irqs | (1 << IPL_TAGINTR);
	}

	/* Lastly, determine which IRQs are actually in use. */
	{
		int irqs = 0;
		for (irq = 0; irq < ICU_LEN; irq++)
			if (intrhand[irq])
				irqs |= 1 << irq;
		if (irqs >= 0x100) /* any IRQs >= 8 in use */
			irqs |= 1 << IRQ_SLAVE;
		imen = ~irqs;
	}
}

static int
fakeintr(arg)
	void *arg;
{

	return 0;
}

#define	LEGAL_IRQ(x)	((x) >= 0 && (x) < ICU_LEN && (x) != 2)

int
isa_intr_alloc(ic, mask, type, irq)
	isa_chipset_tag_t ic;
	int mask;
	int type;
	int *irq;
{
	int i, tmp, bestirq, count;
	struct intrhand **p, *q;

	if (type == IST_NONE)
		panic("intr_alloc: bogus type");

	bestirq = -1;
	count = -1;

	/* some interrupts should never be dynamically allocated */
	mask &= 0xdef8;

	/*
	 * XXX some interrupts will be used later (6 for fdc, 12 for pms).
	 * the right answer is to do "breadth-first" searching of devices.
	 */
	mask &= 0xefbf;

	for (i = 0; i < ICU_LEN; i++) {
		if (LEGAL_IRQ(i) == 0 || (mask & (1<<i)) == 0)
			continue;

		switch(intrtype[i]) {
		case IST_NONE:
			/*
			 * if nothing's using the irq, just return it
			 */
			*irq = i;
			return (0);

		case IST_EDGE:
		case IST_LEVEL:
			if (type != intrtype[i])
				continue;
			/*
			 * if the irq is shareable, count the number of other
			 * handlers, and if it's smaller than the last irq like
			 * this, remember it
			 *
			 * XXX We should probably also consider the
			 * interrupt level and stick IPL_TTY with other
			 * IPL_TTY, etc.
			 */
			for (p = &intrhand[i], tmp = 0; (q = *p) != NULL;
			     p = &q->ih_next, tmp++)
				;
			if ((bestirq == -1) || (count > tmp)) {
				bestirq = i;
				count = tmp;
			}
			break;

		case IST_PULSE:
			/* this just isn't shareable */
			continue;
		}
	}

	if (bestirq == -1)
		return (1);

	*irq = bestirq;

	return (0);
}

const struct evcnt *
isa_intr_evcnt(isa_chipset_tag_t ic, int irq)
{

	/* XXX for now, no evcnt parent reported */
	return NULL;
}

/*
 * Set up an interrupt handler to start being called.
 * XXX PRONE TO RACE CONDITIONS, UGLY, 'INTERESTING' INSERTION ALGORITHM.
 */
void *
isa_intr_establish(ic, irq, type, level, ih_fun, ih_arg)
	isa_chipset_tag_t ic;
	int irq;
	int type;
	int level;
	int (*ih_fun) __P((void *));
	void *ih_arg;
{
	struct intrhand **p, *q, *ih;
	static struct intrhand fakehand = {fakeintr};

#if NMCA > 0
	/*
	 * Need special fake handler for PS/2 MCA clock interrupt
	 */

	if (MCA_system && irq == 0)
		fakehand.ih_fun = &mca_clockfakeintr;
#endif

	/* no point in sleeping unless someone can free memory. */
	ih = malloc(sizeof *ih, M_DEVBUF, cold ? M_NOWAIT : M_WAITOK);
	if (ih == NULL)
		panic("isa_intr_establish: can't malloc handler info");

	if (!LEGAL_IRQ(irq) || type == IST_NONE)
		panic("intr_establish: bogus irq or type");

#if NMCA > 0
	/* change IST_EDGE to IST_LEVEL if MCA system */
	if (MCA_system && type == IST_EDGE)
		type = IST_LEVEL;
#endif

	switch (intrtype[irq]) {
	case IST_NONE:
		intrtype[irq] = type;
		break;
	case IST_EDGE:
	case IST_LEVEL:
		if (type == intrtype[irq])
			break;
	case IST_PULSE:
		if (type != IST_NONE) {
			/*
			 * We can't share interrupts in this case.
			 */
#ifdef DEBUG
			printf("intr_establish: irq %d can't share %s "
			    "with %s\n", irq,
			    isa_intr_typename(intrtype[irq]),
			    isa_intr_typename(type));
#endif
			return (NULL);
		}
		break;
	}

	/*
	 * Figure out where to put the handler.
	 * This is O(N^2), but we want to preserve the order, and N is
	 * generally small.
	 */
	for (p = &intrhand[irq]; (q = *p) != NULL; p = &q->ih_next)
		;

	/*
	 * Actually install a fake handler momentarily, since we might be doing
	 * this with interrupts enabled and don't want the real routine called
	 * until masking is set up.
	 */
	fakehand.ih_level = level;
	*p = &fakehand;

	intr_calculatemasks();

	/*
	 * Poke the real handler in now.
	 */
	ih->ih_fun = ih_fun;
	ih->ih_arg = ih_arg;
	ih->ih_count = 0;
	ih->ih_next = NULL;
	ih->ih_level = level;
	ih->ih_irq = irq;
	*p = ih;

	SET_ICUS();
	return (ih);
}

/*
 * Deregister an interrupt handler.
 */
void
isa_intr_disestablish(ic, arg)
	isa_chipset_tag_t ic;
	void *arg;
{
	struct intrhand *ih = arg;
	int irq = ih->ih_irq;
	struct intrhand **p, *q;

	if (!LEGAL_IRQ(irq))
		panic("intr_disestablish: bogus irq");

	/*
	 * Remove the handler from the chain.
	 * This is O(n^2), too.
	 */
	for (p = &intrhand[irq]; (q = *p) != NULL && q != ih; p = &q->ih_next)
		;
	if (q)
		*p = q->ih_next;
	else
		panic("intr_disestablish: handler not registered");
	free(ih, M_DEVBUF);

	intr_calculatemasks();
	SET_ICUS();

	if (intrhand[irq] == NULL)
		intrtype[irq] = IST_NONE;
}

void
isa_attach_hook(parent, self, iba)
	struct device *parent, *self;
	struct isabus_attach_args *iba;
{
	extern struct i386_isa_chipset i386_isa_chipset;
	extern int isa_has_been_seen;

	/*
	 * Notify others that might need to know that the ISA bus
	 * has now been attached.
	 */
	if (isa_has_been_seen)
		panic("isaattach: ISA bus already seen!");
	isa_has_been_seen = 1;

	/*
	 * Since we can only have one ISA bus, we just use a single
	 * statically allocated ISA chipset structure.  Pass it up
	 * now.
	 */
	iba->iba_ic = &i386_isa_chipset;
}

int
isa_mem_alloc(t, size, align, boundary, flags, addrp, bshp)
	bus_space_tag_t t;
	bus_size_t size, align;
	bus_addr_t boundary;
	int flags;
	bus_addr_t *addrp;
	bus_space_handle_t *bshp;
{

	/*
	 * Allocate physical address space in the ISA hole.
	 */
	return (bus_space_alloc(t, IOM_BEGIN, IOM_END - 1, size, align,
	    boundary, flags, addrp, bshp));
}

void
isa_mem_free(t, bsh, size)
	bus_space_tag_t t;
	bus_space_handle_t bsh;
	bus_size_t size;
{

	bus_space_free(t, bsh, size);
}

/**********************************************************************
 * bus.h dma interface entry points
 **********************************************************************/

#ifdef ISA_DMA_STATS
#define	STAT_INCR(v)	(v)++
#define	STAT_DECR(v)	do { \
		if ((v) == 0) \
			printf("%s:%d -- Already 0!\n", __FILE__, __LINE__); \
		else \
			(v)--; \
		} while (0)
u_long	isa_dma_stats_loads;
u_long	isa_dma_stats_bounces;
u_long	isa_dma_stats_nbouncebufs;
#else
#define	STAT_INCR(v)
#define	STAT_DECR(v)
#endif

/*
 * Create an ISA DMA map.
 */
int
_isa_bus_dmamap_create(t, size, nsegments, maxsegsz, boundary, flags, dmamp)
	bus_dma_tag_t t;
	bus_size_t size;
	int nsegments;
	bus_size_t maxsegsz;
	bus_size_t boundary;
	int flags;
	bus_dmamap_t *dmamp;
{
	struct i386_isa_dma_cookie *cookie;
	bus_dmamap_t map;
	int error, cookieflags;
	void *cookiestore;
	size_t cookiesize;

	/* Call common function to create the basic map. */
	error = _bus_dmamap_create(t, size, nsegments, maxsegsz, boundary,
	    flags, dmamp);
	if (error)
		return (error);

	map = *dmamp;
	map->_dm_cookie = NULL;

	cookiesize = sizeof(struct i386_isa_dma_cookie);

	/*
	 * ISA only has 24-bits of address space.  This means
	 * we can't DMA to pages over 16M.  In order to DMA to
	 * arbitrary buffers, we use "bounce buffers" - pages
	 * in memory below the 16M boundary.  On DMA reads,
	 * DMA happens to the bounce buffers, and is copied into
	 * the caller's buffer.  On writes, data is copied into
	 * but bounce buffer, and the DMA happens from those
	 * pages.  To software using the DMA mapping interface,
	 * this looks simply like a data cache.
	 *
	 * If we have more than 16M of RAM in the system, we may
	 * need bounce buffers.  We check and remember that here.
	 *
	 * There are exceptions, however.  VLB devices can do
	 * 32-bit DMA, and indicate that here.
	 *
	 * ...or, there is an opposite case.  The most segments
	 * a transfer will require is (maxxfer / PAGE_SIZE) + 1.  If
	 * the caller can't handle that many segments (e.g. the
	 * ISA DMA controller), we may have to bounce it as well.
	 */
	if (avail_end <= t->_bounce_thresh ||
	    (flags & ISABUS_DMA_32BIT) != 0) {
		/* Bouncing not necessary due to memory size. */ 
		map->_dm_bounce_thresh = 0;
	}
	cookieflags = 0;
	if (map->_dm_bounce_thresh != 0 ||
	    ((map->_dm_size / PAGE_SIZE) + 1) > map->_dm_segcnt) {
		cookieflags |= ID_MIGHT_NEED_BOUNCE;
		cookiesize += (sizeof(bus_dma_segment_t) * map->_dm_segcnt);
	}

	/*
	 * Allocate our cookie.
	 */
	if ((cookiestore = malloc(cookiesize, M_DMAMAP,
	    (flags & BUS_DMA_NOWAIT) ? M_NOWAIT : M_WAITOK)) == NULL) {
		error = ENOMEM;
		goto out;
	}
	memset(cookiestore, 0, cookiesize);
	cookie = (struct i386_isa_dma_cookie *)cookiestore;
	cookie->id_flags = cookieflags;
	map->_dm_cookie = cookie;

	if (cookieflags & ID_MIGHT_NEED_BOUNCE) {
		/*
		 * Allocate the bounce pages now if the caller
		 * wishes us to do so.
		 */
		if ((flags & BUS_DMA_ALLOCNOW) == 0)
			goto out;

		error = _isa_dma_alloc_bouncebuf(t, map, size, flags);
	}

 out:
	if (error) {
		if (map->_dm_cookie != NULL)
			free(map->_dm_cookie, M_DMAMAP);
		_bus_dmamap_destroy(t, map);
	}
	return (error);
}

/*
 * Destroy an ISA DMA map.
 */
void
_isa_bus_dmamap_destroy(t, map)
	bus_dma_tag_t t;
	bus_dmamap_t map;
{
	struct i386_isa_dma_cookie *cookie = map->_dm_cookie;

	/*
	 * Free any bounce pages this map might hold.
	 */
	if (cookie->id_flags & ID_HAS_BOUNCE)
		_isa_dma_free_bouncebuf(t, map);

	free(cookie, M_DMAMAP);
	_bus_dmamap_destroy(t, map);
}

/*
 * Load an ISA DMA map with a linear buffer.
 */
int
_isa_bus_dmamap_load(t, map, buf, buflen, p, flags)
	bus_dma_tag_t t;
	bus_dmamap_t map; 
	void *buf;
	bus_size_t buflen;
	struct proc *p;
	int flags;
{
	struct i386_isa_dma_cookie *cookie = map->_dm_cookie;
	int error;

	STAT_INCR(isa_dma_stats_loads);

	/*
	 * Make sure that on error condition we return "no valid mappings."
	 */
	map->dm_mapsize = 0;
	map->dm_nsegs = 0;

	/*
	 * Try to load the map the normal way.  If this errors out,
	 * and we can bounce, we will.
	 */
	error = _bus_dmamap_load(t, map, buf, buflen, p, flags);
	if (error == 0 ||
	    (error != 0 && (cookie->id_flags & ID_MIGHT_NEED_BOUNCE) == 0))
		return (error);

	/*
	 * First attempt failed; bounce it.
	 */

	STAT_INCR(isa_dma_stats_bounces);

	/*
	 * Allocate bounce pages, if necessary.
	 */
	if ((cookie->id_flags & ID_HAS_BOUNCE) == 0) {
		error = _isa_dma_alloc_bouncebuf(t, map, buflen, flags);
		if (error)
			return (error);
	}

	/*
	 * Cache a pointer to the caller's buffer and load the DMA map
	 * with the bounce buffer.
	 */
	cookie->id_origbuf = buf;
	cookie->id_origbuflen = buflen;
	cookie->id_buftype = ID_BUFTYPE_LINEAR;
	error = _bus_dmamap_load(t, map, cookie->id_bouncebuf, buflen,
	    p, flags);
	if (error) {
		/*
		 * Free the bounce pages, unless our resources
		 * are reserved for our exclusive use.
		 */
		if ((map->_dm_flags & BUS_DMA_ALLOCNOW) == 0)
			_isa_dma_free_bouncebuf(t, map);
		return (error);
	}

	/* ...so _isa_bus_dmamap_sync() knows we're bouncing */
	cookie->id_flags |= ID_IS_BOUNCING;
	return (0);
}

/*
 * Like _isa_bus_dmamap_load(), but for mbufs.
 */
int
_isa_bus_dmamap_load_mbuf(t, map, m0, flags)  
	bus_dma_tag_t t;
	bus_dmamap_t map;
	struct mbuf *m0;
	int flags;
{
	struct i386_isa_dma_cookie *cookie = map->_dm_cookie;
	int error;

	/*
	 * Make sure on error condition we return "no valid mappings."
	 */
	map->dm_mapsize = 0;
	map->dm_nsegs = 0;

#ifdef DIAGNOSTIC
	if ((m0->m_flags & M_PKTHDR) == 0)
		panic("_isa_bus_dmamap_load_mbuf: no packet header");
#endif

	if (m0->m_pkthdr.len > map->_dm_size)
		return (EINVAL);

	/*
	 * Try to load the map the normal way.  If this errors out,
	 * and we can bounce, we will.
	 */
	error = _bus_dmamap_load_mbuf(t, map, m0, flags);
	if (error == 0 ||
	    (error != 0 && (cookie->id_flags & ID_MIGHT_NEED_BOUNCE) == 0))
		return (error);

	/*
	 * First attempt failed; bounce it.
	 */

	STAT_INCR(isa_dma_stats_bounces);

	/*
	 * Allocate bounce pages, if necessary.
	 */
	if ((cookie->id_flags & ID_HAS_BOUNCE) == 0) {
		error = _isa_dma_alloc_bouncebuf(t, map, m0->m_pkthdr.len,
		    flags);
		if (error)
			return (error);
	}

	/*
	 * Cache a pointer to the caller's buffer and load the DMA map
	 * with the bounce buffer.
	 */
	cookie->id_origbuf = m0;
	cookie->id_origbuflen = m0->m_pkthdr.len;	/* not really used */
	cookie->id_buftype = ID_BUFTYPE_MBUF;
	error = _bus_dmamap_load(t, map, cookie->id_bouncebuf,
	    m0->m_pkthdr.len, NULL, flags);
	if (error) {
		/*
		 * Free the bounce pages, unless our resources
		 * are reserved for our exclusive use.
		 */
		if ((map->_dm_flags & BUS_DMA_ALLOCNOW) == 0)
			_isa_dma_free_bouncebuf(t, map);
		return (error);
	}

	/* ...so _isa_bus_dmamap_sync() knows we're bouncing */
	cookie->id_flags |= ID_IS_BOUNCING;
	return (0);
}

/*
 * Like _isa_bus_dmamap_load(), but for uios.
 */
int
_isa_bus_dmamap_load_uio(t, map, uio, flags)
	bus_dma_tag_t t;
	bus_dmamap_t map;
	struct uio *uio;
	int flags;
{

	panic("_isa_bus_dmamap_load_uio: not implemented");
}

/*
 * Like _isa_bus_dmamap_load(), but for raw memory allocated with
 * bus_dmamem_alloc().
 */
int
_isa_bus_dmamap_load_raw(t, map, segs, nsegs, size, flags)
	bus_dma_tag_t t;
	bus_dmamap_t map;
	bus_dma_segment_t *segs;
	int nsegs;
	bus_size_t size;
	int flags;
{

	panic("_isa_bus_dmamap_load_raw: not implemented");
}

/*
 * Unload an ISA DMA map.
 */
void
_isa_bus_dmamap_unload(t, map)
	bus_dma_tag_t t;
	bus_dmamap_t map;
{
	struct i386_isa_dma_cookie *cookie = map->_dm_cookie;

	/*
	 * If we have bounce pages, free them, unless they're
	 * reserved for our exclusive use.
	 */
	if ((cookie->id_flags & ID_HAS_BOUNCE) &&
	    (map->_dm_flags & BUS_DMA_ALLOCNOW) == 0)
		_isa_dma_free_bouncebuf(t, map);

	cookie->id_flags &= ~ID_IS_BOUNCING;
	cookie->id_buftype = ID_BUFTYPE_INVALID;

	/*
	 * Do the generic bits of the unload.
	 */
	_bus_dmamap_unload(t, map);
}

/*
 * Synchronize an ISA DMA map.
 */
void
_isa_bus_dmamap_sync(t, map, offset, len, ops)
	bus_dma_tag_t t;
	bus_dmamap_t map;
	bus_addr_t offset;
	bus_size_t len;
	int ops;
{
	struct i386_isa_dma_cookie *cookie = map->_dm_cookie;

	/*
	 * Mixing PRE and POST operations is not allowed.
	 */
	if ((ops & (BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE)) != 0 &&
	    (ops & (BUS_DMASYNC_POSTREAD|BUS_DMASYNC_POSTWRITE)) != 0)
		panic("_isa_bus_dmamap_sync: mix PRE and POST");

#ifdef DIAGNOSTIC
	if ((ops & (BUS_DMASYNC_PREWRITE|BUS_DMASYNC_POSTREAD)) != 0) {
		if (offset >= map->dm_mapsize)
			panic("_isa_bus_dmamap_sync: bad offset");
		if (len == 0 || (offset + len) > map->dm_mapsize)
			panic("_isa_bus_dmamap_sync: bad length");
	}
#endif

	/*
	 * If we're not bouncing, just return; nothing to do.
	 */
	if ((cookie->id_flags & ID_IS_BOUNCING) == 0)
		return;

	switch (cookie->id_buftype) {
	case ID_BUFTYPE_LINEAR:
		/*
		 * Nothing to do for pre-read.
		 */

		if (ops & BUS_DMASYNC_PREWRITE) {
			/*
			 * Copy the caller's buffer to the bounce buffer.
			 */
			memcpy((char *)cookie->id_bouncebuf + offset,
			    (char *)cookie->id_origbuf + offset, len);
		}

		if (ops & BUS_DMASYNC_POSTREAD) {
			/*
			 * Copy the bounce buffer to the caller's buffer.
			 */
			memcpy((char *)cookie->id_origbuf + offset,
			    (char *)cookie->id_bouncebuf + offset, len);
		}

		/*
		 * Nothing to do for post-write.
		 */
		break;

	case ID_BUFTYPE_MBUF:
	    {
		struct mbuf *m, *m0 = cookie->id_origbuf;
		bus_size_t minlen, moff;

		/*
		 * Nothing to do for pre-read.
		 */

		if (ops & BUS_DMASYNC_PREWRITE) {
			/*
			 * Copy the caller's buffer to the bounce buffer.
			 */
			m_copydata(m0, offset, len,
			    (char *)cookie->id_bouncebuf + offset);
		}

		if (ops & BUS_DMASYNC_POSTREAD) {
			/*
			 * Copy the bounce buffer to the caller's buffer.
			 */
			for (moff = offset, m = m0; m != NULL && len != 0;
			     m = m->m_next) {
				/* Find the beginning mbuf. */
				if (moff >= m->m_len) {
					moff -= m->m_len;
					continue;
				}

				/*
				 * Now at the first mbuf to sync; nail
				 * each one until we have exhausted the
				 * length.
				 */
				minlen = len < m->m_len - moff ?
				    len : m->m_len - moff;

				memcpy(mtod(m, caddr_t) + moff,
				    (char *)cookie->id_bouncebuf + offset,
				    minlen);

				moff = 0;
				len -= minlen;
				offset += minlen;
			}
		}

		/*
		 * Nothing to do for post-write.
		 */
		break;
	    }

	case ID_BUFTYPE_UIO:
		panic("_isa_bus_dmamap_sync: ID_BUFTYPE_UIO");
		break;

	case ID_BUFTYPE_RAW:
		panic("_isa_bus_dmamap_sync: ID_BUFTYPE_RAW");
		break;

	case ID_BUFTYPE_INVALID:
		panic("_isa_bus_dmamap_sync: ID_BUFTYPE_INVALID");
		break;

	default:
		printf("unknown buffer type %d\n", cookie->id_buftype);
		panic("_isa_bus_dmamap_sync");
	}
}

/*
 * Allocate memory safe for ISA DMA.
 */
int
_isa_bus_dmamem_alloc(t, size, alignment, boundary, segs, nsegs, rsegs, flags)
	bus_dma_tag_t t;
	bus_size_t size, alignment, boundary;
	bus_dma_segment_t *segs;
	int nsegs;
	int *rsegs;
	int flags;
{
	paddr_t high;

	if (avail_end > ISA_DMA_BOUNCE_THRESHOLD)
		high = trunc_page(ISA_DMA_BOUNCE_THRESHOLD);
	else
		high = trunc_page(avail_end);

	return (_bus_dmamem_alloc_range(t, size, alignment, boundary,
	    segs, nsegs, rsegs, flags, 0, high));
}

/**********************************************************************
 * ISA DMA utility functions
 **********************************************************************/

int
_isa_dma_alloc_bouncebuf(t, map, size, flags)
	bus_dma_tag_t t;
	bus_dmamap_t map;
	bus_size_t size;
	int flags;
{
	struct i386_isa_dma_cookie *cookie = map->_dm_cookie;
	int error = 0;

	cookie->id_bouncebuflen = round_page(size);
	error = _isa_bus_dmamem_alloc(t, cookie->id_bouncebuflen,
	    PAGE_SIZE, map->_dm_boundary, cookie->id_bouncesegs,
	    map->_dm_segcnt, &cookie->id_nbouncesegs, flags);
	if (error)
		goto out;
	error = _bus_dmamem_map(t, cookie->id_bouncesegs,
	    cookie->id_nbouncesegs, cookie->id_bouncebuflen,
	    (caddr_t *)&cookie->id_bouncebuf, flags);

 out:
	if (error) {
		_bus_dmamem_free(t, cookie->id_bouncesegs,
		    cookie->id_nbouncesegs);
		cookie->id_bouncebuflen = 0;
		cookie->id_nbouncesegs = 0;
	} else {
		cookie->id_flags |= ID_HAS_BOUNCE;
		STAT_INCR(isa_dma_stats_nbouncebufs);
	}

	return (error);
}

void
_isa_dma_free_bouncebuf(t, map)
	bus_dma_tag_t t;
	bus_dmamap_t map;
{
	struct i386_isa_dma_cookie *cookie = map->_dm_cookie;

	STAT_DECR(isa_dma_stats_nbouncebufs);

	_bus_dmamem_unmap(t, cookie->id_bouncebuf,
	    cookie->id_bouncebuflen);
	_bus_dmamem_free(t, cookie->id_bouncesegs,
	    cookie->id_nbouncesegs);
	cookie->id_bouncebuflen = 0;
	cookie->id_nbouncesegs = 0;
	cookie->id_flags &= ~ID_HAS_BOUNCE;
}

#if NMCA > 0
/*
 * Special fake handler for PS/2 MCA clock interrupts
 */
static int
mca_clockfakeintr(arg)
	void *arg;
{
	/* Reset clock interrupt by asserting bit 7 of port 0x61 */
	outb(0x61, inb(0x61) | 0x80);
	return 0;
}
#endif