xref: /netbsd/sys/arch/i386/mca/mca_machdep.c (revision bf9ec67e)
1 /*	$NetBSD: mca_machdep.c,v 1.14 2001/12/04 20:00:16 sommerfeld Exp $	*/
2 
3 /*-
4  * Copyright (c) 2000, 2001 The NetBSD Foundation, Inc.
5  * Copyright (c) 1996-1999 Scott D. Telford.
6  * All rights reserved.
7  *
8  * This code is derived from software contributed to The NetBSD Foundation
9  * by Scott Telford <s.telford@ed.ac.uk> and Jaromir Dolecek
10  * <jdolecek@NetBSD.org>.
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  *    notice, this list of conditions and the following disclaimer in the
19  *    documentation and/or other materials provided with the distribution.
20  * 3. All advertising materials mentioning features or use of this software
21  *    must display the following acknowledgement:
22  *	This product includes software developed by the NetBSD
23  *	Foundation, Inc. and its contributors.
24  * 4. Neither the name of The NetBSD Foundation nor the names of its
25  *    contributors may be used to endorse or promote products derived
26  *    from this software without specific prior written permission.
27  *
28  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
29  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
30  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
31  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
32  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
33  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
34  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
35  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
36  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
37  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
38  * POSSIBILITY OF SUCH DAMAGE.
39  */
40 
41 /*
42  * Machine-specific functions for MCA autoconfiguration.
43  */
44 
45 #include <sys/cdefs.h>
46 __KERNEL_RCSID(0, "$NetBSD: mca_machdep.c,v 1.14 2001/12/04 20:00:16 sommerfeld Exp $");
47 
48 #include <sys/types.h>
49 #include <sys/param.h>
50 #include <sys/device.h>
51 #include <sys/malloc.h>
52 #include <sys/systm.h>
53 #include <sys/syslog.h>
54 #include <sys/time.h>
55 #include <sys/kernel.h>
56 
57 #include <machine/bioscall.h>
58 #include <machine/psl.h>
59 
60 #define _I386_BUS_DMA_PRIVATE
61 #include <machine/bus.h>
62 
63 #include <i386/isa/icu.h>
64 #include <dev/isa/isavar.h>
65 #include <dev/isa/isareg.h>
66 #include <dev/mca/mcavar.h>
67 #include <dev/mca/mcareg.h>
68 
69 #include "isa.h"
70 #include "opt_mcaverbose.h"
71 
72 /* System Configuration Block - this info is returned by the BIOS call */
73 struct bios_config {
74 	u_int16_t	count;
75 	u_int8_t	model;
76 	u_int8_t	submodel;
77 	u_int8_t	bios_rev;
78 	u_int8_t	feature1;
79 #define FEATURE_MCAISA	0x01	/* Machine contains both MCA and ISA bus */
80 #define FEATURE_MCABUS	0x02	/* Machine has MCA bus instead of ISA	*/
81 #define FEATURE_EBDA	0x04	/* Extended BIOS data area allocated	*/
82 #define FEATURE_WAITEV	0x08	/* Wait for external event is supported	*/
83 #define FEATURE_KBDINT	0x10	/* Keyboard intercept called by Int 09h	*/
84 #define FEATURE_RTC	0x20	/* Real-time clock present		*/
85 #define FEATURE_IC2	0x40	/* Second interrupt chip present	*/
86 #define FEATURE_DMA3	0x80	/* DMA channel 3 used by hard disk BIOS	*/
87 	u_int8_t	feature2;
88 	u_int8_t	pad[9];
89 } __attribute__ ((packed));
90 
91 /*
92  * Used to encode DMA channel into ISA DMA cookie. We use upper 4 bits of
93  * ISA DMA cookie id_flags, it's unused.
94  */
95 struct i386_isa_dma_cookie {
96 	int id_flags;
97 	/* We don't care about rest */
98 };
99 
100 /* ISA DMA stuff - see i386/isa/isa_machdep.c */
101 int	_isa_bus_dmamap_create __P((bus_dma_tag_t, bus_size_t, int,
102 	    bus_size_t, bus_size_t, int, bus_dmamap_t *));
103 void	_isa_bus_dmamap_destroy __P((bus_dma_tag_t, bus_dmamap_t));
104 int	_isa_bus_dmamap_load __P((bus_dma_tag_t, bus_dmamap_t, void *,
105 	    bus_size_t, struct proc *, int));
106 void	_isa_bus_dmamap_unload __P((bus_dma_tag_t, bus_dmamap_t));
107 void	_isa_bus_dmamap_sync __P((bus_dma_tag_t, bus_dmamap_t,
108 	    bus_addr_t, bus_size_t, int));
109 
110 int	_isa_bus_dmamem_alloc __P((bus_dma_tag_t, bus_size_t, bus_size_t,
111 	    bus_size_t, bus_dma_segment_t *, int, int *, int));
112 
113 static void	_mca_bus_dmamap_sync __P((bus_dma_tag_t, bus_dmamap_t,
114 		    bus_addr_t, bus_size_t, int));
115 static int	_mca_bus_dmamap_load_mbuf __P((bus_dma_tag_t, bus_dmamap_t,
116 		    struct mbuf *, int));
117 static int	_mca_bus_dmamap_load_uio __P((bus_dma_tag_t, bus_dmamap_t,
118 		    struct uio *, int));
119 static int	_mca_bus_dmamap_load_raw __P((bus_dma_tag_t, bus_dmamap_t,
120 		    bus_dma_segment_t *, int, bus_size_t, int));
121 
122 /*
123  * For now, we use MCA DMA to 0-16M always. Some IBM PS/2 have 32bit MCA bus,
124  * but majority of them have 24bit only.
125  */
126 #define	MCA_DMA_BOUNCE_THRESHOLD	(16 * 1024 * 1024)
127 
128 struct i386_bus_dma_tag mca_bus_dma_tag = {
129 	MCA_DMA_BOUNCE_THRESHOLD,		/* _bounce_thresh */
130 	_isa_bus_dmamap_create,
131 	_isa_bus_dmamap_destroy,
132 	_isa_bus_dmamap_load,
133 	_mca_bus_dmamap_load_mbuf,
134 	_mca_bus_dmamap_load_uio,
135 	_mca_bus_dmamap_load_raw,
136 	_isa_bus_dmamap_unload,
137 	_mca_bus_dmamap_sync,
138 	_isa_bus_dmamem_alloc,
139 	_bus_dmamem_free,
140 	_bus_dmamem_map,
141 	_bus_dmamem_unmap,
142 	_bus_dmamem_mmap,
143 };
144 
145 /* Updated in mca_busprobe() if appropriate. */
146 int MCA_system = 0;
147 
148 /* Used to kick MCA DMA controller */
149 #define DMA_CMD		0x18		/* command the controller */
150 #define DMA_EXEC	0x1A		/* tell controller how to do things */
151 static bus_space_handle_t dmaiot, dmacmdh, dmaexech;
152 
153 /*
154  * MCA DMA controller commands. The exact sense of individual bits
155  * are from Tymm Twillman <tymm@computer.org>, who worked on Linux MCA DMA
156  * support.
157  */
158 #define DMACMD_SET_IO		0x00	/* set port (16bit) for i/o transfer */
159 #define DMACMD_SET_ADDR		0x20	/* set addr (24bit) for i/o transfer */
160 #define DMACMD_GET_ADDR		0x30	/* get addr (24bit) for i/o transfer */
161 #define	DMACMD_SET_CNT		0x40	/* set memory size for DMA (16b) */
162 #define DMACMD_GET_CNT		0x50	/* get count of remaining bytes in DMA*/
163 #define DMACMD_GET_STATUS	0x60	/* ?? */
164 #define DMACMD_SET_MODE		0x70	/* set DMA mode */
165 # define DMACMD_MODE_XFER	0x04	/* do transfer, read by default */
166 # define DMACMD_MODE_READ	0x08	/* read transfer */
167 # define DMACMD_MODE_WRITE	0x00	/* write transfer */
168 # define DMACMD_MODE_IOPORT	0x01	/* DMA from/to IO register */
169 # define DMACMD_MODE_16BIT	0x40	/* 16bit transfers (default 8bit) */
170 #define DMACMD_SET_ARBUS	0x80	/* ?? */
171 #define DMACMD_MASK		0x90	/* command mask */
172 #define DMACMD_RESET_MASK	0xA0	/* reset */
173 #define DMACMD_MASTER_CLEAR	0xD0	/* ?? */
174 
175 /*
176  * Map the MCA DMA controller registers.
177  */
178 void
179 mca_attach_hook(parent, self, mba)
180 	struct device *parent, *self;
181 	struct mcabus_attach_args *mba;
182 {
183 	dmaiot = mba->mba_iot;
184 
185 	if (bus_space_map(dmaiot, DMA_CMD, 1, 0, &dmacmdh)
186 	    || bus_space_map(dmaiot, DMA_EXEC, 1, 0, &dmaexech))
187 		panic("%s: couldn't map DMA registers",
188 			mba->mba_busname);
189 }
190 
191 /*
192  * Read value of MCA POS register "reg" in slot "slot".
193  */
194 
195 int
196 mca_conf_read(mc, slot, reg)
197 	mca_chipset_tag_t mc;
198 	int slot, reg;
199 {
200 	int	data;
201 
202 	slot &= 7;	/* slot must be in range 0-7 */
203 	outb(MCA_MB_SETUP_REG, 0xff); /* ensure m/board setup is disabled */
204 	outb(MCA_ADAP_SETUP_REG, slot | MCA_ADAP_SET);
205 	data = inb(MCA_POS_REG(reg));
206 	outb(MCA_ADAP_SETUP_REG, 0);
207 	return data;
208 }
209 
210 
211 /*
212  * Write "data" to MCA POS register "reg" in slot "slot".
213  */
214 
215 void
216 mca_conf_write(mc, slot, reg, data)
217 	mca_chipset_tag_t mc;
218 	int slot, reg, data;
219 {
220 	slot&=7;	/* slot must be in range 0-7 */
221 	outb(MCA_MB_SETUP_REG, 0xff); /* ensure m/board setup is disabled */
222 	outb(MCA_ADAP_SETUP_REG, slot | MCA_ADAP_SET);
223 	outb(MCA_POS_REG(reg), data);
224 	outb(MCA_ADAP_SETUP_REG, 0);
225 }
226 
227 #if NISA <= 0
228 #error mca_intr_(dis)establish: needs ISA to be configured into kernel
229 #endif
230 
231 #if 0
232 const struct evcnt *
233 mca_intr_establish(mca_chipset_tag_t mc, mca_intr_handle_t ih)
234 {
235 
236 	/* XXX for now, no evcnt parent reported */
237 	return NULL;
238 }
239 #endif
240 
241 void *
242 mca_intr_establish(mc, ih, level, func, arg)
243 	mca_chipset_tag_t mc;
244 	mca_intr_handle_t ih;
245 	int level, (*func) __P((void *));
246 	void *arg;
247 {
248 	if (ih == 0 || ih >= ICU_LEN || ih == 2)
249 		panic("mca_intr_establish: bogus handle 0x%x\n", ih);
250 
251 	/* MCA interrupts are always level-triggered */
252 	return isa_intr_establish(NULL, ih, IST_LEVEL, level, func, arg);
253 }
254 
255 void
256 mca_intr_disestablish(mc, cookie)
257 	mca_chipset_tag_t mc;
258 	void *cookie;
259 {
260 	return isa_intr_disestablish(NULL, cookie);
261 }
262 
263 
264 /*
265  * Handle a NMI.
266  * return true to panic system, false to ignore.
267  */
268 int
269 mca_nmi()
270 {
271 	/*
272 	* PS/2 MCA devices can generate NMIs - we can find out which
273 	* slot generated it from the POS registers.
274 	*/
275 
276 	int 	slot, mcanmi=0;
277 
278 	/* if there is no MCA bus, call isa_nmi() */
279 	if (!MCA_system)
280 		goto out;
281 
282 	/* ensure motherboard setup is disabled */
283 	outb(MCA_MB_SETUP_REG, 0xff);
284 
285 	/* find if an MCA slot has the CHCK bit asserted (low) in POS 5 */
286 	for(slot=0; slot<MCA_MAX_SLOTS; slot++) {
287 		outb(MCA_ADAP_SETUP_REG, slot | MCA_ADAP_SET);
288 		if ((inb(MCA_POS_REG(5)) & MCA_POS5_CHCK) == 0) {
289 			mcanmi = 1;
290 			/* find if CHCK status is available in POS 6/7 */
291 			if((inb(MCA_POS_REG(5)) & MCA_POS5_CHCK_STAT) == 0)
292 				log(LOG_CRIT, "MCA NMI: slot %d, POS6=0x%02x, POS7=0x%02x\n",
293 					slot+1, inb(MCA_POS_REG(6)),
294 						inb(MCA_POS_REG(7)));
295 			else
296 				log(LOG_CRIT, "MCA NMI: slot %d\n", slot+1);
297 		}
298 	}
299 	outb(MCA_ADAP_SETUP_REG, 0);
300 
301    out:
302 	if (!mcanmi) {
303 		/* no CHCK bits asserted, assume ISA NMI */
304 		return (isa_nmi());
305 	} else
306 		return(0);
307 }
308 
309 /*
310  * We can obtain the information about MCA bus presence via
311  * GET CONFIGURATION BIOS call - int 0x15, function 0xc0.
312  * The call returns a pointer to memory place with the configuration block
313  * in es:bx (on AT-compatible, e.g. all we care about, computers).
314  *
315  * Configuration block contains block length (2 bytes), model
316  * number (1 byte), submodel number (1 byte), BIOS revision
317  * (1 byte) and up to 5 feature bytes. We only care about
318  * first feature byte.
319  */
320 void
321 mca_busprobe()
322 {
323 	struct bioscallregs regs;
324 	struct bios_config *scp;
325 	paddr_t             paddr;
326 	char buf[50];
327 
328 	memset(&regs, 0, sizeof(regs));
329 	regs.AH = 0xc0;
330 	bioscall(0x15, &regs);
331 
332 	if ((regs.EFLAGS & PSL_C) || regs.AH != 0) {
333 #ifdef DEBUG
334 		printf("BIOS CFG: Not supported. Not AT-compatible?\n");
335 #endif
336 		return;
337 	}
338 
339 	paddr = (regs.ES << 4) + regs.BX;
340 	scp = (struct bios_config *)ISA_HOLE_VADDR(paddr);
341 
342 #if 1 /* MCAVERBOSE */
343 	bitmask_snprintf(((scp->feature2 & 1)<< 8) | scp->feature1,
344 		"\20"
345 		"\01MCA+ISA"
346 		"\02MCA"
347 		"\03EBDA"
348 		"\04WAITEV"
349 		"\05KBDINT"
350 		"\06RTC"
351 		"\07IC2"
352 		"\010DMA3B"
353 		"\011DMA32\n",
354 		buf, sizeof(buf));
355 
356 	printf("BIOS CFG: Model-SubM-Rev: %02x-%02x-%02x, 0x%s\n",
357 		scp->model, scp->submodel, scp->bios_rev, buf);
358 #endif
359 
360 	MCA_system = (scp->feature1 & FEATURE_MCABUS) ? 1 : 0;
361 }
362 
363 #define PORT_DISKLED	0x92
364 #define DISKLED_ON	0x40
365 
366 /*
367  * Light disk busy LED on IBM PS/2.
368  */
369 void
370 mca_disk_busy(void)
371 {
372 	outb(PORT_DISKLED, inb(PORT_DISKLED) | DISKLED_ON);
373 }
374 
375 /*
376  * Turn off disk LED on IBM PS/2.
377  */
378 void
379 mca_disk_unbusy(void)
380 {
381 	outb(PORT_DISKLED, inb(PORT_DISKLED) & ~DISKLED_ON);
382 }
383 
384 /*
385  * -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
386  * MCA DMA specific stuff. We use ISA routines for bulk of the work,
387  * since MCA shares much of the charasteristics with it. We just hook
388  * the DMA channel initialization and kick MCA DMA controller appropriately.
389  * -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
390  */
391 
392 /*
393  * Like _mca_bus_dmamap_load(), but for mbufs.
394  */
395 static int
396 _mca_bus_dmamap_load_mbuf(t, map, m0, flags)
397 	bus_dma_tag_t t;
398 	bus_dmamap_t map;
399 	struct mbuf *m0;
400 	int flags;
401 {
402 
403 	panic("_mca_bus_dmamap_load_mbuf: not implemented");
404 }
405 
406 /*
407  * Like _mca_bus_dmamap_load(), but for uios.
408  */
409 static int
410 _mca_bus_dmamap_load_uio(t, map, uio, flags)
411 	bus_dma_tag_t t;
412 	bus_dmamap_t map;
413 	struct uio *uio;
414 	int flags;
415 {
416 
417 	panic("_mca_bus_dmamap_load_uio: not implemented");
418 }
419 
420 /*
421  * Like _mca_bus_dmamap_load(), but for raw memory allocated with
422  * bus_dmamem_alloc().
423  */
424 static int
425 _mca_bus_dmamap_load_raw(t, map, segs, nsegs, size, flags)
426 	bus_dma_tag_t t;
427 	bus_dmamap_t map;
428 	bus_dma_segment_t *segs;
429 	int nsegs;
430 	bus_size_t size;
431 	int flags;
432 {
433 
434 	panic("_mca_bus_dmamap_load_raw: not implemented");
435 }
436 
437 /*
438  * Synchronize a MCA DMA map.
439  */
440 static void
441 _mca_bus_dmamap_sync(t, map, offset, len, ops)
442 	bus_dma_tag_t t;
443 	bus_dmamap_t map;
444 	bus_addr_t offset;
445 	bus_size_t len;
446 	int ops;
447 {
448 	struct i386_isa_dma_cookie *cookie;
449 	bus_addr_t phys;
450 	bus_size_t cnt;
451 	int dmach, mode;
452 
453 	_isa_bus_dmamap_sync(t, map, offset, len, ops);
454 
455 	/*
456 	 * Don't do anything if not using the DMA controller.
457 	 */
458 	if ((map->_dm_flags & _MCABUS_DMA_USEDMACTRL) == 0)
459 		return;
460 
461 	/*
462 	 * Don't do anything if not PRE* operation, allow only
463 	 * one of PREREAD and PREWRITE.
464 	 */
465 	if (ops != BUS_DMASYNC_PREREAD && ops != BUS_DMASYNC_PREWRITE)
466 		return;
467 
468 	cookie = (struct i386_isa_dma_cookie *)map->_dm_cookie;
469 	dmach = (cookie->id_flags & 0xf0) >> 4;
470 
471 	phys = map->dm_segs[0].ds_addr;
472 	cnt = map->dm_segs[0].ds_len;
473 
474 	mode = DMACMD_MODE_XFER;
475 	mode |= (ops == BUS_DMASYNC_PREREAD)
476 			? DMACMD_MODE_READ : DMACMD_MODE_WRITE;
477 	if (map->_dm_flags & MCABUS_DMA_IOPORT)
478 		mode |= DMACMD_MODE_IOPORT;
479 
480 	/* Use 16bit DMA if requested */
481 	if (map->_dm_flags & MCABUS_DMA_16BIT) {
482 #ifdef DIAGNOSTIC
483 		if ((cnt % 2) != 0) {
484 			panic("_mca_bus_dmamap_sync: 16bit DMA and cnt %lu odd",
485 				cnt);
486 		}
487 #endif
488 		mode |= DMACMD_MODE_16BIT;
489 		cnt /= 2;
490 	}
491 
492 	/*
493 	 * Initialize the MCA DMA controller appropriately. The exact
494 	 * sequence to setup the controller is taken from Minix.
495 	 */
496 
497 	/* Disable access to dma channel. */
498 	bus_space_write_1(dmaiot, dmacmdh, 0, DMACMD_MASK | dmach);
499 
500 	/* Set the transfer mode. */
501 	bus_space_write_1(dmaiot, dmacmdh, 0, DMACMD_SET_MODE | dmach);
502 	bus_space_write_1(dmaiot, dmaexech, 0, mode);
503 
504 	/* Set the address byte pointer. */
505 	bus_space_write_1(dmaiot, dmacmdh, 0, DMACMD_SET_ADDR | dmach);
506 	/* address bits 0..7   */
507 	bus_space_write_1(dmaiot, dmaexech, 0, (phys >> 0) & 0xff);
508 	/* address bits 8..15  */
509 	bus_space_write_1(dmaiot, dmaexech, 0, (phys >> 8) & 0xff);
510 	/* address bits 16..23  */
511 	bus_space_write_1(dmaiot, dmaexech, 0, (phys >> 16) & 0xff);
512 
513 	/* Set the count byte pointer */
514 	bus_space_write_1(dmaiot, dmacmdh, 0, DMACMD_SET_CNT | dmach);
515 	/* count bits 0..7     */
516 	bus_space_write_1(dmaiot, dmaexech, 0, ((cnt - 1) >> 0) & 0xff);
517 	/* count bits 8..15    */
518 	bus_space_write_1(dmaiot, dmaexech, 0, ((cnt - 1) >> 8) & 0xff);
519 
520 	/* Enable access to dma channel. */
521 	bus_space_write_1(dmaiot, dmacmdh, 0, DMACMD_RESET_MASK | dmach);
522 }
523 
524 /*
525  * Allocate a dma map, and set up dma channel.
526  */
527 int
528 mca_dmamap_create(t, size, flags, dmamp, dmach)
529 	bus_dma_tag_t t;
530 	bus_size_t size;
531 	int flags;
532 	bus_dmamap_t *dmamp;
533 	int dmach;
534 {
535 	int error;
536 	struct i386_isa_dma_cookie *cookie;
537 
538 #ifdef DEBUG
539 	/* Sanity check */
540 	if (dmach < 0 || dmach >= 16) {
541 		printf("mcadma_create: invalid DMA channel %d\n",
542 			dmach);
543 		return (EINVAL);
544 	}
545 
546 	if (size > 65536) {
547 		panic("mca_dmamap_create: dmamap sz %ld > 65536",
548 		    (long) size);
549 	}
550 #endif
551 
552 	/*
553 	 * MCA DMA transfer can be maximum 65536 bytes long and must
554 	 * be in one chunk. No specific boundary constraints are present.
555 	 */
556 	if ((error = bus_dmamap_create(t, size, 1, 65536, 0, flags, dmamp)))
557 		return (error);
558 
559 	/* Encode DMA channel */
560 	cookie = (struct i386_isa_dma_cookie *) (*dmamp)->_dm_cookie;
561 	cookie->id_flags &= 0x0f;
562 	cookie->id_flags |= dmach << 4;
563 
564 	/* Mark the dmamap as using DMA controller. Some devices
565 	 * drive DMA themselves, and don't need the MCA DMA controller.
566 	 * To distinguish the two, use a flag for dmamaps which use the DMA
567 	 * controller.
568  	 */
569 	(*dmamp)->_dm_flags |= _MCABUS_DMA_USEDMACTRL;
570 
571 	return (0);
572 }
573 
574 /*
575  * Set I/O port for DMA. Implemented separately from _mca_bus_dmamap_sync()
576  * so that it's available for one-shot setup.
577  */
578 void
579 mca_dma_set_ioport(dma, port)
580 	int dma;
581 	u_int16_t port;
582 {
583 	/* Disable access to dma channel. */
584 	bus_space_write_1(dmaiot, dmacmdh, 0, DMACMD_MASK | dma);
585 
586 	/* Set I/O port to use for DMA */
587 	bus_space_write_1(dmaiot, dmacmdh, 0, DMACMD_SET_IO | dma);
588 	bus_space_write_1(dmaiot, dmaexech, 0, port & 0xff);
589 	bus_space_write_1(dmaiot, dmaexech, 0, (port >> 8) & 0xff);
590 
591 	/* Enable access to dma channel. */
592 	bus_space_write_1(dmaiot, dmacmdh, 0, DMACMD_RESET_MASK | dma);
593 }
594