xref: /netbsd-src/sys/arch/macppc/dev/wdc_obio.c (revision 8b0f9554ff8762542c4defc4f70e1eb76fb508fa)
1 /*	$NetBSD: wdc_obio.c,v 1.47 2007/10/17 19:55:20 garbled Exp $	*/
2 
3 /*-
4  * Copyright (c) 1998, 2003 The NetBSD Foundation, Inc.
5  * All rights reserved.
6  *
7  * This code is derived from software contributed to The NetBSD Foundation
8  * by Charles M. Hannum and by Onno van der Linden.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. All advertising materials mentioning features or use of this software
19  *    must display the following acknowledgement:
20  *        This product includes software developed by the NetBSD
21  *        Foundation, Inc. and its contributors.
22  * 4. Neither the name of The NetBSD Foundation nor the names of its
23  *    contributors may be used to endorse or promote products derived
24  *    from this software without specific prior written permission.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36  * POSSIBILITY OF SUCH DAMAGE.
37  */
38 
39 #include <sys/cdefs.h>
40 __KERNEL_RCSID(0, "$NetBSD: wdc_obio.c,v 1.47 2007/10/17 19:55:20 garbled Exp $");
41 
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/device.h>
45 #include <sys/malloc.h>
46 
47 #include <uvm/uvm_extern.h>
48 
49 #include <machine/bus.h>
50 #include <machine/autoconf.h>
51 #include <machine/pio.h>
52 
53 #include <dev/ata/atareg.h>
54 #include <dev/ata/atavar.h>
55 #include <dev/ic/wdcvar.h>
56 
57 #include <dev/ofw/openfirm.h>
58 
59 #include <macppc/dev/dbdma.h>
60 
61 #define WDC_REG_NPORTS		8
62 #define WDC_AUXREG_OFFSET	0x16
63 #define WDC_DEFAULT_PIO_IRQ	13	/* XXX */
64 #define WDC_DEFAULT_DMA_IRQ	2	/* XXX */
65 
66 #define WDC_OPTIONS_DMA 0x01
67 
68 /*
69  * XXX This code currently doesn't even try to allow 32-bit data port use.
70  */
71 
72 struct wdc_obio_softc {
73 	struct wdc_softc sc_wdcdev;
74 	struct ata_channel *sc_chanptr;
75 	struct ata_channel sc_channel;
76 	struct ata_queue sc_chqueue;
77 	struct wdc_regs sc_wdc_regs;
78 	bus_space_handle_t sc_dmaregh;
79 	dbdma_regmap_t *sc_dmareg;
80 	dbdma_command_t	*sc_dmacmd;
81 	u_int sc_dmaconf[2];	/* per target value of CONFIG_REG */
82 	void *sc_ih;
83 };
84 
85 int wdc_obio_probe __P((struct device *, struct cfdata *, void *));
86 void wdc_obio_attach __P((struct device *, struct device *, void *));
87 int wdc_obio_detach __P((struct device *, int));
88 int wdc_obio_dma_init __P((void *, int, int, void *, size_t, int));
89 void wdc_obio_dma_start __P((void *, int, int));
90 int wdc_obio_dma_finish __P((void *, int, int, int));
91 
92 static void wdc_obio_select __P((struct ata_channel *, int));
93 static void adjust_timing __P((struct ata_channel *));
94 static void ata4_adjust_timing __P((struct ata_channel *));
95 
96 CFATTACH_DECL(wdc_obio, sizeof(struct wdc_obio_softc),
97     wdc_obio_probe, wdc_obio_attach, wdc_obio_detach, wdcactivate);
98 
99 static const char *ata_names[] = {
100     "heathrow-ata",
101     "keylargo-ata",
102     "ohare-ata",
103     NULL
104 };
105 
106 int
107 wdc_obio_probe(parent, match, aux)
108 	struct device *parent;
109 	struct cfdata *match;
110 	void *aux;
111 {
112 	struct confargs *ca = aux;
113 
114 	/* XXX should not use name */
115 	if (strcmp(ca->ca_name, "ATA") == 0 ||
116 	    strcmp(ca->ca_name, "ata") == 0 ||
117 	    strcmp(ca->ca_name, "ata0") == 0 ||
118 	    strcmp(ca->ca_name, "ide") == 0)
119 		return 1;
120 
121 	if (of_compatible(ca->ca_node, ata_names) >= 0)
122 		return 1;
123 
124 	return 0;
125 }
126 
127 void
128 wdc_obio_attach(parent, self, aux)
129 	struct device *parent, *self;
130 	void *aux;
131 {
132 	struct wdc_obio_softc *sc = (void *)self;
133 	struct wdc_regs *wdr;
134 	struct confargs *ca = aux;
135 	struct ata_channel *chp = &sc->sc_channel;
136 	int intr, i, type = IST_EDGE;
137 	int use_dma = 0;
138 	char path[80];
139 
140 	if (device_cfdata(&sc->sc_wdcdev.sc_atac.atac_dev)->cf_flags &
141 	    WDC_OPTIONS_DMA) {
142 		if (ca->ca_nreg >= 16 || ca->ca_nintr == -1)
143 			use_dma = 1;	/* XXX Don't work yet. */
144 	}
145 
146 	if (ca->ca_nintr >= 4 && ca->ca_nreg >= 8) {
147 		intr = ca->ca_intr[0];
148 		printf(" irq %d", intr);
149 		if (ca->ca_nintr > 8) {
150 			type = ca->ca_intr[1] ? IST_LEVEL : IST_EDGE;
151 		}
152 		printf(", %s triggered", (type == IST_EDGE) ? "edge" : "level");
153 	} else if (ca->ca_nintr == -1) {
154 		intr = WDC_DEFAULT_PIO_IRQ;
155 		printf(" irq property not found; using %d", intr);
156 	} else {
157 		printf(": couldn't get irq property\n");
158 		return;
159 	}
160 
161 	if (use_dma)
162 		printf(": DMA transfer");
163 
164 	printf("\n");
165 
166 	sc->sc_wdcdev.regs = wdr = &sc->sc_wdc_regs;
167 
168 	wdr->cmd_iot = wdr->ctl_iot = ca->ca_tag;
169 
170 	if (bus_space_map(wdr->cmd_iot, ca->ca_baseaddr + ca->ca_reg[0],
171 	    WDC_REG_NPORTS << 4, 0, &wdr->cmd_baseioh) ||
172 	    bus_space_subregion(wdr->cmd_iot, wdr->cmd_baseioh,
173 			WDC_AUXREG_OFFSET << 4, 1, &wdr->ctl_ioh)) {
174 		printf("%s: couldn't map registers\n",
175 			sc->sc_wdcdev.sc_atac.atac_dev.dv_xname);
176 		return;
177 	}
178 
179 	for (i = 0; i < WDC_NREG; i++) {
180 		if (bus_space_subregion(wdr->cmd_iot, wdr->cmd_baseioh, i << 4,
181 		    i == 0 ? 4 : 1, &wdr->cmd_iohs[i]) != 0) {
182 			bus_space_unmap(wdr->cmd_iot, wdr->cmd_baseioh,
183 			    WDC_REG_NPORTS << 4);
184 			printf("%s: couldn't subregion registers\n",
185 			    sc->sc_wdcdev.sc_atac.atac_dev.dv_xname);
186 			return;
187 		}
188 	}
189 #if 0
190 	wdr->data32iot = wdr->cmd_iot;
191 	wdr->data32ioh = wdr->cmd_ioh;
192 #endif
193 
194 	sc->sc_ih = intr_establish(intr, type, IPL_BIO, wdcintr, chp);
195 
196 	if (use_dma) {
197 		sc->sc_dmacmd = dbdma_alloc(sizeof(dbdma_command_t) * 20);
198 		/*
199 		 * XXX
200 		 * we don't use ca->ca_reg[3] for size here because at least
201 		 * on the PB3400c it says 0x200 for both IDE channels ( the
202 		 * one on the mainboard and the other on the mediabay ) but
203 		 * their start addresses are only 0x100 apart. Since those
204 		 * DMA registers are always 0x100 or less we don't really
205 		 * have to care though
206 		 */
207 		if (bus_space_map(wdr->cmd_iot, ca->ca_baseaddr + ca->ca_reg[2],
208 		    0x100, BUS_SPACE_MAP_LINEAR, &sc->sc_dmaregh)) {
209 
210 			aprint_error("%s: unable to map DMA registers (%08x)\n",
211 			    sc->sc_wdcdev.sc_atac.atac_dev.dv_xname,
212 			    ca->ca_reg[2]);
213 			/* should unmap stuff here */
214 			return;
215 		}
216 		sc->sc_dmareg = bus_space_vaddr(wdr->cmd_iot, sc->sc_dmaregh);
217 
218 		sc->sc_wdcdev.sc_atac.atac_cap |= ATAC_CAP_DMA;
219 		sc->sc_wdcdev.sc_atac.atac_dma_cap = 2;
220 		if (strcmp(ca->ca_name, "ata-4") == 0) {
221 			sc->sc_wdcdev.sc_atac.atac_cap |= ATAC_CAP_UDMA;
222 			sc->sc_wdcdev.sc_atac.atac_udma_cap = 4;
223 			sc->sc_wdcdev.sc_atac.atac_set_modes =
224 			    ata4_adjust_timing;
225 		} else {
226 			sc->sc_wdcdev.sc_atac.atac_set_modes = adjust_timing;
227 		}
228 #ifdef notyet
229 		/* Minimum cycle time is 150ns (DMA MODE 1) on ohare. */
230 		if (ohare) {
231 			sc->sc_wdcdev.sc_atac.atac_pio_cap = 3;
232 			sc->sc_wdcdev.sc_atac.atac_dma_cap = 1;
233 		}
234 #endif
235 	} else {
236 		/* all non-DMA controllers can use adjust_timing */
237 		sc->sc_wdcdev.sc_atac.atac_set_modes = adjust_timing;
238 	}
239 
240 	sc->sc_wdcdev.sc_atac.atac_pio_cap = 4;
241 	sc->sc_wdcdev.sc_atac.atac_cap |= ATAC_CAP_DATA16;
242 	sc->sc_chanptr = chp;
243 	sc->sc_wdcdev.sc_atac.atac_channels = &sc->sc_chanptr;
244 	sc->sc_wdcdev.sc_atac.atac_nchannels = 1;
245 	sc->sc_wdcdev.dma_arg = sc;
246 	sc->sc_wdcdev.dma_init = wdc_obio_dma_init;
247 	sc->sc_wdcdev.dma_start = wdc_obio_dma_start;
248 	sc->sc_wdcdev.dma_finish = wdc_obio_dma_finish;
249 	chp->ch_channel = 0;
250 	chp->ch_atac = &sc->sc_wdcdev.sc_atac;
251 	chp->ch_queue = &sc->sc_chqueue;
252 	chp->ch_ndrive = 2;
253 
254 	wdc_init_shadow_regs(chp);
255 
256 #define OHARE_FEATURE_REG	0xf3000038
257 
258 	/* XXX Enable wdc1 by feature reg. */
259 	memset(path, 0, sizeof(path));
260 	OF_package_to_path(ca->ca_node, path, sizeof(path));
261 	if (strcmp(path, "/bandit@F2000000/ohare@10/ata@21000") == 0) {
262 		u_int x;
263 
264 		x = in32rb(OHARE_FEATURE_REG);
265 		x |= 8;
266 		out32rb(OHARE_FEATURE_REG, x);
267 	}
268 
269 	wdcattach(chp);
270 }
271 
272 /* Multiword DMA transfer timings */
273 struct ide_timings {
274 	int cycle;	/* minimum cycle time [ns] */
275 	int active;	/* minimum command active time [ns] */
276 };
277 static struct ide_timings pio_timing[5] = {
278 	{ 600, 180 },    /* Mode 0 */
279 	{ 390, 150 },    /*      1 */
280 	{ 240, 105 },    /*      2 */
281 	{ 180,  90 },    /*      3 */
282 	{ 120,  75 }     /*      4 */
283 };
284 static struct ide_timings dma_timing[3] = {
285 	{ 480, 240 },	/* Mode 0 */
286 	{ 165,  90 },	/* Mode 1 */
287 	{ 120,  75 }	/* Mode 2 */
288 };
289 
290 static struct ide_timings udma_timing[5] = {
291 	{120, 180},	/* Mode 0 */
292 	{ 90, 150},	/* Mode 1 */
293 	{ 60, 120},	/* Mode 2 */
294 	{ 45, 90},	/* Mode 3 */
295 	{ 30, 90}	/* Mode 4 */
296 };
297 
298 #define TIME_TO_TICK(time) howmany((time), 30)
299 #define PIO_REC_OFFSET 4
300 #define PIO_REC_MIN 1
301 #define PIO_ACT_MIN 1
302 #define DMA_REC_OFFSET 1
303 #define DMA_REC_MIN 1
304 #define DMA_ACT_MIN 1
305 
306 #define ATA4_TIME_TO_TICK(time)  howmany((time), 15) /* 15 ns clock */
307 
308 #define CONFIG_REG (0x200)		/* IDE access timing register */
309 
310 void
311 wdc_obio_select(chp, drive)
312 	struct ata_channel *chp;
313 	int drive;
314 {
315 	struct wdc_obio_softc *sc = (struct wdc_obio_softc *)chp->ch_atac;
316 	struct wdc_regs *wdr = CHAN_TO_WDC_REGS(chp);
317 
318 	bus_space_write_4(wdr->cmd_iot, wdr->cmd_baseioh,
319 			CONFIG_REG, sc->sc_dmaconf[drive]);
320 }
321 
322 void
323 adjust_timing(chp)
324 	struct ata_channel *chp;
325 {
326 	struct wdc_obio_softc *sc = (struct wdc_obio_softc *)chp->ch_atac;
327 	int drive;
328 	int min_cycle = 0, min_active = 0;
329 	int cycle_tick = 0, act_tick = 0, inact_tick = 0, half_tick;
330 
331 	for (drive = 0; drive < 2; drive++) {
332 		u_int conf = 0;
333 		struct ata_drive_datas *drvp;
334 
335 		drvp = &chp->ch_drive[drive];
336 		/* set up pio mode timings */
337 		if (drvp->drive_flags & DRIVE) {
338 			int piomode = drvp->PIO_mode;
339 			min_cycle = pio_timing[piomode].cycle;
340 			min_active = pio_timing[piomode].active;
341 
342 			cycle_tick = TIME_TO_TICK(min_cycle);
343 			act_tick = TIME_TO_TICK(min_active);
344 			if (act_tick < PIO_ACT_MIN)
345 				act_tick = PIO_ACT_MIN;
346 			inact_tick = cycle_tick - act_tick - PIO_REC_OFFSET;
347 			if (inact_tick < PIO_REC_MIN)
348 				inact_tick = PIO_REC_MIN;
349 			/* mask: 0x000007ff */
350 			conf |= (inact_tick << 5) | act_tick;
351 		}
352 		/* Set up DMA mode timings */
353 		if (drvp->drive_flags & DRIVE_DMA) {
354 			int dmamode = drvp->DMA_mode;
355 			min_cycle = dma_timing[dmamode].cycle;
356 			min_active = dma_timing[dmamode].active;
357 			cycle_tick = TIME_TO_TICK(min_cycle);
358 			act_tick = TIME_TO_TICK(min_active);
359 			inact_tick = cycle_tick - act_tick - DMA_REC_OFFSET;
360 			if (inact_tick < DMA_REC_MIN)
361 				inact_tick = DMA_REC_MIN;
362 			half_tick = 0;	/* XXX */
363 			/* mask: 0xfffff800 */
364 			conf |=
365 					(half_tick << 21) |
366 					(inact_tick << 16) | (act_tick << 11);
367 		}
368 #ifdef DEBUG
369 		if (conf) {
370 			printf("conf[%d] = 0x%x, cyc = %d (%d ns), act = %d (%d ns), inact = %d\n",
371 					drive, conf, cycle_tick, min_cycle, act_tick, min_active, inact_tick);
372 		}
373 #endif
374 		sc->sc_dmaconf[drive] = conf;
375 	}
376 	sc->sc_wdcdev.select = 0;
377 	if (sc->sc_dmaconf[0]) {
378 		wdc_obio_select(chp,0);
379 		if (sc->sc_dmaconf[1] &&
380 		    (sc->sc_dmaconf[0] != sc->sc_dmaconf[1])) {
381 			sc->sc_wdcdev.select = wdc_obio_select;
382 		}
383 	} else if (sc->sc_dmaconf[1]) {
384 		wdc_obio_select(chp,1);
385 	}
386 }
387 
388 void
389 ata4_adjust_timing(chp)
390 	struct ata_channel *chp;
391 {
392 	struct wdc_obio_softc *sc = (struct wdc_obio_softc *)chp->ch_atac;
393 	int drive;
394 	int min_cycle = 0, min_active = 0;
395 	int cycle_tick = 0, act_tick = 0, inact_tick = 0;
396 
397 	for (drive = 0; drive < 2; drive++) {
398 		u_int conf = 0;
399 		struct ata_drive_datas *drvp;
400 
401 		drvp = &chp->ch_drive[drive];
402 		/* set up pio mode timings */
403 
404 		if (drvp->drive_flags & DRIVE) {
405 			int piomode = drvp->PIO_mode;
406 			min_cycle = pio_timing[piomode].cycle;
407 			min_active = pio_timing[piomode].active;
408 
409 			cycle_tick = ATA4_TIME_TO_TICK(min_cycle);
410 			act_tick = ATA4_TIME_TO_TICK(min_active);
411 			inact_tick = cycle_tick - act_tick;
412 			/* mask: 0x000003ff */
413 			conf |= (inact_tick << 5) | act_tick;
414 		}
415 		/* set up dma mode timings */
416 		if (drvp->drive_flags & DRIVE_DMA) {
417 			int dmamode = drvp->DMA_mode;
418 			min_cycle = dma_timing[dmamode].cycle;
419 			min_active = dma_timing[dmamode].active;
420 			cycle_tick = ATA4_TIME_TO_TICK(min_cycle);
421 			act_tick = ATA4_TIME_TO_TICK(min_active);
422 			inact_tick = cycle_tick - act_tick;
423 			/* mask: 0x001ffc00 */
424 			conf |= (act_tick << 10) | (inact_tick << 15);
425 		}
426 		/* set up udma mode timings */
427 		if (drvp->drive_flags & DRIVE_UDMA) {
428 			int udmamode = drvp->UDMA_mode;
429 			min_cycle = udma_timing[udmamode].cycle;
430 			min_active = udma_timing[udmamode].active;
431 			act_tick = ATA4_TIME_TO_TICK(min_active);
432 			cycle_tick = ATA4_TIME_TO_TICK(min_cycle);
433 			/* mask: 0x1ff00000 */
434 			conf |= (cycle_tick << 21) | (act_tick << 25) | 0x100000;
435 		}
436 #ifdef DEBUG
437 		if (conf) {
438 			printf("ata4 conf[%d] = 0x%x, cyc = %d (%d ns), act = %d (%d ns), inact = %d\n",
439 					drive, conf, cycle_tick, min_cycle, act_tick, min_active, inact_tick);
440 		}
441 #endif
442 		sc->sc_dmaconf[drive] = conf;
443 	}
444 	sc->sc_wdcdev.select = 0;
445 	if (sc->sc_dmaconf[0]) {
446 		wdc_obio_select(chp,0);
447 		if (sc->sc_dmaconf[1] &&
448 		    (sc->sc_dmaconf[0] != sc->sc_dmaconf[1])) {
449 			sc->sc_wdcdev.select = wdc_obio_select;
450 		}
451 	} else if (sc->sc_dmaconf[1]) {
452 		wdc_obio_select(chp,1);
453 	}
454 }
455 
456 int
457 wdc_obio_detach(self, flags)
458 	struct device *self;
459 	int flags;
460 {
461 	struct wdc_obio_softc *sc = (void *)self;
462 	int error;
463 
464 	if ((error = wdcdetach(self, flags)) != 0)
465 		return error;
466 
467 	intr_disestablish(sc->sc_ih);
468 
469 	/* Unmap our i/o space. */
470 	bus_space_unmap(sc->sc_wdcdev.regs->cmd_iot,
471 			sc->sc_wdcdev.regs->cmd_baseioh, WDC_REG_NPORTS << 4);
472 
473 	/* Unmap DMA registers. */
474 	/* XXX unmapiodev(sc->sc_dmareg); */
475 	/* XXX free(sc->sc_dmacmd); */
476 
477 	return 0;
478 }
479 
480 int
481 wdc_obio_dma_init(v, channel, drive, databuf, datalen, flags)
482 	void *v;
483 	void *databuf;
484 	size_t datalen;
485 	int flags;
486 {
487 	struct wdc_obio_softc *sc = v;
488 	vaddr_t va = (vaddr_t)databuf;
489 	dbdma_command_t *cmdp;
490 	u_int cmd, offset;
491 	int read = flags & WDC_DMA_READ;
492 
493 	cmdp = sc->sc_dmacmd;
494 	cmd = read ? DBDMA_CMD_IN_MORE : DBDMA_CMD_OUT_MORE;
495 
496 	offset = va & PGOFSET;
497 
498 	/* if va is not page-aligned, setup the first page */
499 	if (offset != 0) {
500 		int rest = PAGE_SIZE - offset;	/* the rest of the page */
501 
502 		if (datalen > rest) {		/* if continues to next page */
503 			DBDMA_BUILD(cmdp, cmd, 0, rest, vtophys(va),
504 				DBDMA_INT_NEVER, DBDMA_WAIT_NEVER,
505 				DBDMA_BRANCH_NEVER);
506 			datalen -= rest;
507 			va += rest;
508 			cmdp++;
509 		}
510 	}
511 
512 	/* now va is page-aligned */
513 	while (datalen > PAGE_SIZE) {
514 		DBDMA_BUILD(cmdp, cmd, 0, PAGE_SIZE, vtophys(va),
515 			DBDMA_INT_NEVER, DBDMA_WAIT_NEVER, DBDMA_BRANCH_NEVER);
516 		datalen -= PAGE_SIZE;
517 		va += PAGE_SIZE;
518 		cmdp++;
519 	}
520 
521 	/* the last page (datalen <= PAGE_SIZE here) */
522 	cmd = read ? DBDMA_CMD_IN_LAST : DBDMA_CMD_OUT_LAST;
523 	DBDMA_BUILD(cmdp, cmd, 0, datalen, vtophys(va),
524 		DBDMA_INT_NEVER, DBDMA_WAIT_NEVER, DBDMA_BRANCH_NEVER);
525 	cmdp++;
526 
527 	DBDMA_BUILD(cmdp, DBDMA_CMD_STOP, 0, 0, 0,
528 		DBDMA_INT_NEVER, DBDMA_WAIT_NEVER, DBDMA_BRANCH_NEVER);
529 
530 	return 0;
531 }
532 
533 void
534 wdc_obio_dma_start(v, channel, drive)
535 	void *v;
536 	int channel, drive;
537 {
538 	struct wdc_obio_softc *sc = v;
539 
540 	dbdma_start(sc->sc_dmareg, sc->sc_dmacmd);
541 }
542 
543 int
544 wdc_obio_dma_finish(v, channel, drive, read)
545 	void *v;
546 	int channel, drive;
547 	int read;
548 {
549 	struct wdc_obio_softc *sc = v;
550 
551 	dbdma_stop(sc->sc_dmareg);
552 	return 0;
553 }
554