xref: /freebsd-10-stable/sys/x86/isa/isa.c

/*-
 * 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
 *
 * PATCHES MAGIC                LEVEL   PATCH THAT GOT US HERE
 * --------------------         -----   ----------------------
 * CURRENT PATCH LEVEL:         4       00163
 * --------------------         -----   ----------------------
 *
 * 18 Aug 92	Frank Maclachlan	*See comments below
 * 25 Mar 93	Rodney W. Grimes	Added counter for stray interrupt,
 *					turned on logging of stray interrupts,
 *					Now prints maddr, msize, and flags
 *					after finding a device.
 * 26 Apr 93	Bruce Evans		New intr-0.1 code
 *		Rodney W. Grimes	Only print io address if id_alive != -1
 * 17 May 93	Rodney W. Grimes	renamed stray interrupt counters to
 *					work with new intr-0.1 code.
 *					Enabled printf for interrupt masks to
 *					aid in bug reports.
 * 27 May 93	Guido van Rooij		New routine add find_isa_dev
 */
static char rcsid[] = "$Header: /usr/src/sys.386bsd/i386/isa/RCS/isa.c,v 1.2 92/01/21 14:34:23 william Exp Locker: root $";

/*
 * code to manage AT bus
 *
 * 92/08/18  Frank P. MacLachlan (fpm@crash.cts.com):
 * Fixed uninitialized variable problem and added code to deal
 * with DMA page boundaries in isa_dmarangecheck().  Fixed word
 * mode DMA count compution and reorganized DMA setup code in
 * isa_dmastart()
 */

#include "param.h"
#include "systm.h"
#include "conf.h"
#include "file.h"
#include "buf.h"
#include "uio.h"
#include "syslog.h"
#include "malloc.h"
#include "rlist.h"
#include "machine/segments.h"
#include "vm/vm.h"
#include "i386/isa/isa_device.h"
#include "i386/isa/isa.h"
#include "i386/isa/icu.h"
#include "i386/isa/ic/i8237.h"
#include "i386/isa/ic/i8042.h"

/*
**  Register definitions for DMA controller 1 (channels 0..3):
*/
#define	DMA1_CHN(c)	(IO_DMA1 + 1*(2*(c)))	/* addr reg for channel c */
#define	DMA1_SMSK	(IO_DMA1 + 1*10)	/* single mask register */
#define	DMA1_MODE	(IO_DMA1 + 1*11)	/* mode register */
#define	DMA1_FFC	(IO_DMA1 + 1*12)	/* clear first/last FF */

/*
**  Register definitions for DMA controller 2 (channels 4..7):
*/
#define	DMA2_CHN(c)	(IO_DMA1 + 2*(2*(c)))	/* addr reg for channel c */
#define	DMA2_SMSK	(IO_DMA2 + 2*10)	/* single mask register */
#define	DMA2_MODE	(IO_DMA2 + 2*11)	/* mode register */
#define	DMA2_FFC	(IO_DMA2 + 2*12)	/* clear first/last FF */

int config_isadev __P((struct isa_device *, u_int *));

#ifdef notyet
struct rlist *isa_iomem;

/*
 * Configure all ISA devices
 */
isa_configure() {
	struct isa_device *dvp;
	struct isa_driver *dp;

	splhigh();
	INTREN(IRQ_SLAVE);
	/*rlist_free(&isa_iomem, 0xa0000, 0xfffff);*/
	for (dvp = isa_devtab_tty; dvp; dvp++)
			(void) config_isadev(dvp, &ttymask);
	for (dvp = isa_devtab_bio; dvp; dvp++)
			(void) config_isadev(dvp, &biomask);
	for (dvp = isa_devtab_net; dvp; dvp++)
			(void) config_isadev(dvp, &netmask);
	for (dvp = isa_devtab_null; dvp; dvp++)
			(void) config_isadev(dvp, (u_int *) NULL);
#include "sl.h"
#if NSL > 0
	netmask |= ttymask;
	ttymask |= netmask;
#endif
/* printf("biomask %x ttymask %x netmask %x\n", biomask, ttymask, netmask); */
	splnone();
}

/*
 * Configure an ISA device.
 */
config_isadev(isdp, mp)
	struct isa_device *isdp;
	u_int *mp;
{
	struct isa_driver *dp;
	static short drqseen, irqseen;

	if (dp = isdp->id_driver) {
		/* if a device with i/o memory, convert to virtual address */
		if (isdp->id_maddr) {
			extern unsigned int atdevbase;

			isdp->id_maddr -= IOM_BEGIN;
			isdp->id_maddr += atdevbase;
		}
		isdp->id_alive = (*dp->probe)(isdp);
		if (isdp->id_alive) {

			printf("%s%d at port 0x%x ", dp->name,
				isdp->id_unit, isdp->id_iobase);

			/* check for conflicts */
			if (irqseen & isdp->id_irq) {
				printf("INTERRUPT CONFLICT - irq%d\n",
					ffs(isdp->id_irq) - 1);
				return (0);
			}
			if (isdp->id_drq != -1
				&& (drqseen & (1<<isdp->id_drq))) {
				printf("DMA CONFLICT - drq%d\n", isdp->id_drq);
				return (0);
			}
			/* NEED TO CHECK IOMEM CONFLICT HERE */

			/* allocate and wire in device */
			if(isdp->id_irq) {
				int intrno;

				intrno = ffs(isdp->id_irq)-1;
				printf("irq %d ", intrno);
				INTREN(isdp->id_irq);
				if(mp)INTRMASK(*mp,isdp->id_irq);
				setidt(NRSVIDT + intrno, isdp->id_intr,
					 SDT_SYS386IGT, SEL_KPL);
				irqseen |= isdp->id_irq;
			}
			if (isdp->id_drq != -1) {
				printf("drq %d ", isdp->id_drq);
				drqseen |=  1 << isdp->id_drq;
			}

			(*dp->attach)(isdp);

			printf("on isa\n");
		}
		return (1);
	} else	return(0);
}
#else /* notyet */
/*
 * Configure all ISA devices
 */
isa_configure() {
	struct isa_device *dvp;
	struct isa_driver *dp;

	enable_intr();
	splhigh();
	INTREN(IRQ_SLAVE);
	for (dvp = isa_devtab_tty; config_isadev(dvp,&ttymask); dvp++);
	for (dvp = isa_devtab_bio; config_isadev(dvp,&biomask); dvp++);
	for (dvp = isa_devtab_net; config_isadev(dvp,&netmask); dvp++);
	for (dvp = isa_devtab_null; config_isadev(dvp,(u_int *) NULL); dvp++);
#include "sl.h"
#if NSL > 0
	netmask |= ttymask;
	ttymask |= netmask;
#endif
	/* biomask |= ttymask ;  can some tty devices use buffers? */
	printf("biomask %x ttymask %x netmask %x\n", biomask, ttymask, netmask);
	splnone();
}

/*
 * Configure an ISA device.
 */
config_isadev(isdp, mp)
	struct isa_device *isdp;
	u_int *mp;
{
	struct isa_driver *dp;

	if (dp = isdp->id_driver) {
		if (isdp->id_maddr) {
			extern u_int atdevbase;

			isdp->id_maddr -= 0xa0000; /* XXX should be a define */
			isdp->id_maddr += atdevbase;
		}
		isdp->id_alive = (*dp->probe)(isdp);
		if (isdp->id_alive) {
			printf("%s%d", dp->name, isdp->id_unit);
			/*
			 * The attach should really be after all the printf's
			 * but until all the drivers are fixed do it here.
			 * There is a comment below that shows where this
			 * really belongs.  Rod Grimes 04/10/93
			 */
			(*dp->attach)(isdp);
			/*
			 * Only print the I/O address range if id_alive != -1
			 * Right now this is a temporary fix just for the new
			 * NPX code so that if it finds a 486 that can use trap
			 * 16 it will not report I/O addresses.
			 * Rod Grimes 04/26/94
			 */
			if (isdp->id_alive != -1) {
	 			printf(" at 0x%x", isdp->id_iobase);
 				if ((isdp->id_iobase + isdp->id_alive - 1) !=
 				     isdp->id_iobase)
 					printf("-0x%x",
 					       isdp->id_iobase +
					       isdp->id_alive - 1);
			}
			if(isdp->id_irq)
				printf(" irq %d", ffs(isdp->id_irq)-1);
			if (isdp->id_drq != -1)
				printf(" drq %d", isdp->id_drq);
			if (isdp->id_maddr != 0)
				printf(" maddr 0x%x", kvtop(isdp->id_maddr));
			if (isdp->id_msize != 0)
				printf(" msize %d", isdp->id_msize);
			if (isdp->id_flags != 0)
				printf(" flags 0x%x", isdp->id_flags);
			printf(" on isa\n");

			/* This is the place the attach should be done! */
			if(isdp->id_irq) {
				int intrno;

				intrno = ffs(isdp->id_irq)-1;
				setidt(ICU_OFFSET+intrno, isdp->id_intr,
					 SDT_SYS386IGT, SEL_KPL);
				if(mp)
					INTRMASK(*mp,isdp->id_irq);
				INTREN(isdp->id_irq);
			}
		}
		return (1);
	} else	return(0);
}
#endif /* (!) notyet */

#define	IDTVEC(name)	__CONCAT(X,name)
/* default interrupt vector table entries */
extern	IDTVEC(intr0), IDTVEC(intr1), IDTVEC(intr2), IDTVEC(intr3),
	IDTVEC(intr4), IDTVEC(intr5), IDTVEC(intr6), IDTVEC(intr7),
	IDTVEC(intr8), IDTVEC(intr9), IDTVEC(intr10), IDTVEC(intr11),
	IDTVEC(intr12), IDTVEC(intr13), IDTVEC(intr14), IDTVEC(intr15);

static *defvec[16] = {
	&IDTVEC(intr0), &IDTVEC(intr1), &IDTVEC(intr2), &IDTVEC(intr3),
	&IDTVEC(intr4), &IDTVEC(intr5), &IDTVEC(intr6), &IDTVEC(intr7),
	&IDTVEC(intr8), &IDTVEC(intr9), &IDTVEC(intr10), &IDTVEC(intr11),
	&IDTVEC(intr12), &IDTVEC(intr13), &IDTVEC(intr14), &IDTVEC(intr15) };

/* out of range default interrupt vector gate entry */
extern	IDTVEC(intrdefault);

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

	/* icu vectors */
	for (i = NRSVIDT ; i < NRSVIDT+ICU_LEN ; i++)
		setidt(i, defvec[i],  SDT_SYS386IGT, SEL_KPL);

	/* out of range vectors */
	for (i = NRSVIDT; i < NIDT; i++)
		setidt(i, &IDTVEC(intrdefault), SDT_SYS386IGT, SEL_KPL);

	/* initialize 8259's */
	outb(IO_ICU1, 0x11);		/* reset; program device, four bytes */
	outb(IO_ICU1+1, NRSVIDT);	/* starting at this vector index */
	outb(IO_ICU1+1, 1<<2);		/* 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, 0x0a);		/* default to IRR on read */
	outb(IO_ICU1, 0xc0 | (3 - 1));	/* pri order 3-7, 0-2 (com2 first) */

	outb(IO_ICU2, 0x11);		/* reset; program device, four bytes */
	outb(IO_ICU2+1, NRSVIDT+8);	/* staring at this vector index */
	outb(IO_ICU2+1,2);		/* my slave id is 2 */
#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, 0x0a);		/* default to IRR on read */
}

/* region of physical memory known to be contiguous */
vm_offset_t isaphysmem;
static caddr_t dma_bounce[8];		/* XXX */
static char bounced[8];		/* XXX */
#define MAXDMASZ 512		/* XXX */

/* high byte of address is stored in this port for i-th dma channel */
static short dmapageport[8] =
	{ 0x87, 0x83, 0x81, 0x82, 0x8f, 0x8b, 0x89, 0x8a };

/*
 * isa_dmacascade(): program 8237 DMA controller channel to accept
 * external dma control by a board.
 */
void isa_dmacascade(unsigned chan)
{
	if (chan > 7)
		panic("isa_dmacascade: impossible request");

	/* set dma channel mode, and set dma channel mode */
	if ((chan & 4) == 0) {
		outb(DMA1_MODE, DMA37MD_CASCADE | chan);
		outb(DMA1_SMSK, chan);
	} else {
		outb(DMA2_MODE, DMA37MD_CASCADE | (chan & 3));
		outb(DMA2_SMSK, chan & 3);
	}
}

/*
 * isa_dmastart(): program 8237 DMA controller channel, avoid page alignment
 * problems by using a bounce buffer.
 */
void isa_dmastart(int flags, caddr_t addr, unsigned nbytes, unsigned chan)
{	vm_offset_t phys;
	int waport;
	caddr_t newaddr;

	if (    chan > 7
	    || (chan < 4 && nbytes > (1<<16))
	    || (chan >= 4 && (nbytes > (1<<17) || (u_int)addr & 1)))
		panic("isa_dmastart: impossible request");

	if (isa_dmarangecheck(addr, nbytes, chan)) {
		if (dma_bounce[chan] == 0)
			dma_bounce[chan] =
				/*(caddr_t)malloc(MAXDMASZ, M_TEMP, M_WAITOK);*/
				(caddr_t) isaphysmem + NBPG*chan;
		bounced[chan] = 1;
		newaddr = dma_bounce[chan];
		*(int *) newaddr = 0;	/* XXX */

		/* copy bounce buffer on write */
		if (!(flags & B_READ))
			bcopy(addr, newaddr, nbytes);
		addr = newaddr;
	}

	/* translate to physical */
	phys = pmap_extract(pmap_kernel(), (vm_offset_t)addr);

	if ((chan & 4) == 0) {
		/*
		 * Program one of DMA channels 0..3.  These are
		 * byte mode channels.
		 */
		/* set dma channel mode, and reset address ff */
		if (flags & B_READ)
			outb(DMA1_MODE, DMA37MD_SINGLE|DMA37MD_WRITE|chan);
		else
			outb(DMA1_MODE, DMA37MD_SINGLE|DMA37MD_READ|chan);
		outb(DMA1_FFC, 0);

		/* send start address */
		waport =  DMA1_CHN(chan);
		outb(waport, phys);
		outb(waport, phys>>8);
		outb(dmapageport[chan], phys>>16);

		/* send count */
		outb(waport + 1, --nbytes);
		outb(waport + 1, nbytes>>8);

		/* unmask channel */
		outb(DMA1_SMSK, chan);
	} else {
		/*
		 * Program one of DMA channels 4..7.  These are
		 * word mode channels.
		 */
		/* set dma channel mode, and reset address ff */
		if (flags & B_READ)
			outb(DMA2_MODE, DMA37MD_SINGLE|DMA37MD_WRITE|(chan&3));
		else
			outb(DMA2_MODE, DMA37MD_SINGLE|DMA37MD_READ|(chan&3));
		outb(DMA2_FFC, 0);

		/* send start address */
		waport = DMA2_CHN(chan - 4);
		outb(waport, phys>>1);
		outb(waport, phys>>9);
		outb(dmapageport[chan], phys>>16);

		/* send count */
		nbytes >>= 1;
		outb(waport + 2, --nbytes);
		outb(waport + 2, nbytes>>8);

		/* unmask channel */
		outb(DMA2_SMSK, chan & 3);
	}
}

void isa_dmadone(int flags, caddr_t addr, int nbytes, int chan)
{

	/* copy bounce buffer on read */
	/*if ((flags & (B_PHYS|B_READ)) == (B_PHYS|B_READ))*/
	if (bounced[chan]) {
		bcopy(dma_bounce[chan], addr, nbytes);
		bounced[chan] = 0;
	}
}

/*
 * Check for problems with the address range of a DMA transfer
 * (non-contiguous physical pages, outside of bus address space,
 * crossing DMA page boundaries).
 * Return true if special handling needed.
 */

isa_dmarangecheck(caddr_t va, unsigned length, unsigned chan) {
	vm_offset_t phys, priorpage = 0, endva;
	u_int dma_pgmsk = (chan & 4) ?  ~(128*1024-1) : ~(64*1024-1);

	endva = (vm_offset_t)round_page(va + length);
	for (; va < (caddr_t) endva ; va += NBPG) {
		phys = trunc_page(pmap_extract(pmap_kernel(), (vm_offset_t)va));
#define ISARAM_END	RAM_END
		if (phys == 0)
			panic("isa_dmacheck: no physical page present");
		if (phys > ISARAM_END)
			return (1);
		if (priorpage) {
			if (priorpage + NBPG != phys)
				return (1);
			/* check if crossing a DMA page boundary */
			if (((u_int)priorpage ^ (u_int)phys) & dma_pgmsk)
				return (1);
		}
		priorpage = phys;
	}
	return (0);
}

/* head of queue waiting for physmem to become available */
struct buf isa_physmemq;

/* blocked waiting for resource to become free for exclusive use */
static isaphysmemflag;
/* if waited for and call requested when free (B_CALL) */
static void (*isaphysmemunblock)(); /* needs to be a list */

/*
 * Allocate contiguous physical memory for transfer, returning
 * a *virtual* address to region. May block waiting for resource.
 * (assumed to be called at splbio())
 */
caddr_t
isa_allocphysmem(caddr_t va, unsigned length, void (*func)()) {

	isaphysmemunblock = func;
	while (isaphysmemflag & B_BUSY) {
		isaphysmemflag |= B_WANTED;
		sleep(&isaphysmemflag, PRIBIO);
	}
	isaphysmemflag |= B_BUSY;

	return((caddr_t)isaphysmem);
}

/*
 * Free contiguous physical memory used for transfer.
 * (assumed to be called at splbio())
 */
void
isa_freephysmem(caddr_t va, unsigned length) {

	isaphysmemflag &= ~B_BUSY;
	if (isaphysmemflag & B_WANTED) {
		isaphysmemflag &= B_WANTED;
		wakeup(&isaphysmemflag);
		if (isaphysmemunblock)
			(*isaphysmemunblock)();
	}
}

/*
 * Handle a NMI, possibly a machine check.
 * return true to panic system, false to ignore.
 */
isa_nmi(cd) {

	log(LOG_CRIT, "\nNMI port 61 %x, port 70 %x\n", inb(0x61), inb(0x70));
	return(0);
}

/*
 * Caught a stray interrupt, notify
 */
isa_strayintr(d) {

	/* DON'T BOTHER FOR NOW! */
	/* for some reason, we get bursts of intr #7, even if not enabled! */
	/*
	 * Well the reason you got bursts of intr #7 is because someone
	 * raised an interrupt line and dropped it before the 8259 could
	 * prioritize it.  This is documented in the intel data book.  This
	 * means you have BAD hardware!  I have changed this so that only
	 * the first 5 get logged, then it quits logging them, and puts
	 * out a special message. rgrimes 3/25/1993
	 */
	extern u_long intrcnt_stray;

	intrcnt_stray++;
	if (intrcnt_stray <= 5)
		log(LOG_ERR,"ISA strayintr %x\n", d);
	if (intrcnt_stray == 5)
		log(LOG_CRIT,"Too many ISA strayintr not logging any more\n");
}

/*
 * Wait "n" microseconds.
 * Relies on timer 1 counting down from (TIMER_FREQ / hz) at
 * (2 * TIMER_FREQ) Hz.
 * Note: timer had better have been programmed before this is first used!
 * (The standard programming causes the timer to generate a square wave and
 * the counter is decremented twice every cycle.)
 */
#define	CF		(2 * TIMER_FREQ)
#define	TIMER_FREQ	1193182	/* XXX - should be elsewhere */

extern int hz;			/* XXX - should be elsewhere */

int DELAY(n)
	int n;
{
	int counter_limit;
	int prev_tick;
	int tick;
	int ticks_left;
	int sec;
	int usec;

#ifdef DELAYDEBUG
	int getit_calls = 1;
	int n1;
	static int state = 0;

	if (state == 0) {
		state = 1;
		for (n1 = 1; n1 <= 10000000; n1 *= 10)
			DELAY(n1);
		state = 2;
	}
	if (state == 1)
		printf("DELAY(%d)...", n);
#endif

	/*
	 * Read the counter first, so that the rest of the setup overhead is
	 * counted.  Guess the initial overhead is 20 usec (on most systems it
	 * takes about 1.5 usec for each of the i/o's in getit().  The loop
	 * takes about 6 usec on a 486/33 and 13 usec on a 386/20.  The
	 * multiplications and divisions to scale the count take a while).
	 */
	prev_tick = getit(0, 0);
	n -= 20;

	/*
	 * Calculate (n * (CF / 1e6)) without using floating point and without
	 * any avoidable overflows.
	 */
	sec = n / 1000000;
	usec = n - sec * 1000000;
	ticks_left = sec * CF
		     + usec * (CF / 1000000)
		     + usec * ((CF % 1000000) / 1000) / 1000
		     + usec * (CF % 1000) / 1000000;

	counter_limit = TIMER_FREQ / hz;
	while (ticks_left > 0) {
		tick = getit(0, 0);
#ifdef DELAYDEBUG
		++getit_calls;
#endif
		if (tick > prev_tick)
			ticks_left -= prev_tick - (tick - counter_limit);
		else
			ticks_left -= prev_tick - tick;
		prev_tick = tick;
	}
#ifdef DELAYDEBUG
	if (state == 1)
		printf(" %d calls to getit() at %d usec each\n",
		       getit_calls, (n + 5) / getit_calls);
#endif
}

getit(unit, timer) {
	int high;
	int low;

	/*
	 * XXX - isa.h defines bogus timers.  There's no such timer as
	 * IO_TIMER_2 = 0x48.  There's a timer in the CMOS RAM chip but
	 * its interface is quite different.  Neither timer is an 8252.
	 * We actually only call this with unit = 0 and timer = 0.  It
	 * could be static...
	 */
	/*
	 * Protect ourself against interrupts.
	 * XXX - sysbeep() and sysbeepstop() need protection.
	 */
	disable_intr();
	/*
	 * Latch the count for 'timer' (cc00xxxx, c = counter, x = any).
	 */
	outb(IO_TIMER1 + 3, timer << 6);

	low = inb(IO_TIMER1 + timer);
	high = inb(IO_TIMER1 + timer);
	enable_intr();
	return ((high << 8) | low);
}

static beeping;
static
sysbeepstop(f)
{
	/* disable counter 2 */
	outb(0x61, inb(0x61) & 0xFC);
	if (f)
		timeout(sysbeepstop, 0, f);
	else
		beeping = 0;
}

void sysbeep(int pitch, int period)
{

	outb(0x61, inb(0x61) | 3);	/* enable counter 2 */
	/*
	 * XXX - move timer stuff to clock.c.
	 * Program counter 2:
	 * ccaammmb, c counter, a = access, m = mode, b = BCD
	 * 1011x110, 11 for aa = LSB then MSB, x11 for mmm = square wave.
	 */
	outb(0x43, 0xb6);	/* set command for counter 2, 2 byte write */

	outb(0x42, pitch);
	outb(0x42, (pitch>>8));

	if (!beeping) {
		beeping = period;
		timeout(sysbeepstop, period/2, period);
	}
}

/*
 * Pass command to keyboard controller (8042)
 */
unsigned kbc_8042cmd(val) {

	while (inb(KBSTATP)&KBS_IBF);
	if (val) outb(KBCMDP, val);
	while (inb(KBSTATP)&KBS_IBF);
	return (inb(KBDATAP));
}

/*
 * find an ISA device in a given isa_devtab_* table, given
 * the table to search, the expected id_driver entry, and the unit number.
 *
 * this function is defined in isa_device.h, and this location is debatable;
 * i put it there because it's useless w/o, and directly operates on
 * the other stuff in that file.
 *
 */

struct isa_device *find_isadev(table, driverp, unit)
     struct isa_device *table;
     struct isa_driver *driverp;
     int unit;
{
  if (driverp == NULL) /* sanity check */
    return NULL;

  while ((table->id_driver != driverp) || (table->id_unit != unit)) {
    if (table->id_driver == 0)
      return NULL;

    table++;
  }

  return table;
}

/*
 * Return nonzero if a (masked) irq is pending for a given device.
 */
int
isa_irq_pending(dvp)
	struct isa_device *dvp;
{
	unsigned id_irq;

	id_irq = (unsigned short) dvp->id_irq;	/* XXX silly type in struct */
	if (id_irq & 0xff)
		return (inb(IO_ICU1) & id_irq);
	return (inb(IO_ICU2) & (id_irq >> 8));
}