xref: /openbsd/sys/dev/pci/pcscp.c (revision 798bf0b9)
1 /*	$OpenBSD: pcscp.c,v 1.10 2005/08/09 04:10:13 mickey Exp $	*/
2 /*	$NetBSD: pcscp.c,v 1.11 2000/11/14 18:42:58 thorpej Exp $	*/
3 
4 /*-
5  * Copyright (c) 1997, 1998, 1999 The NetBSD Foundation, Inc.
6  * All rights reserved.
7  *
8  * This code is derived from software contributed to The NetBSD Foundation
9  * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
10  * NASA Ames Research Center; Izumi Tsutsui.
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  * pcscp.c: device dependent code for AMD Am53c974 (PCscsi-PCI)
43  * written by Izumi Tsutsui <tsutsui@ceres.dti.ne.jp>
44  *
45  * Technical manual available at
46  * http://www.amd.com/products/npd/techdocs/techdocs.html
47  */
48 
49 #include <sys/param.h>
50 #include <sys/systm.h>
51 #include <sys/device.h>
52 #include <sys/buf.h>
53 
54 #include <machine/bus.h>
55 #include <machine/intr.h>
56 #include <machine/endian.h>
57 
58 #include <scsi/scsi_all.h>
59 #include <scsi/scsiconf.h>
60 #include <scsi/scsi_message.h>
61 
62 #include <dev/pci/pcireg.h>
63 #include <dev/pci/pcivar.h>
64 #include <dev/pci/pcidevs.h>
65 
66 #include <dev/ic/ncr53c9xreg.h>
67 #include <dev/ic/ncr53c9xvar.h>
68 
69 #include <dev/pci/pcscpreg.h>
70 
71 #define IO_MAP_REG	0x10
72 #define MEM_MAP_REG	0x14
73 
74 struct pcscp_softc {
75 	struct ncr53c9x_softc sc_ncr53c9x;	/* glue to MI code */
76 
77 	bus_space_tag_t sc_st;		/* bus space tag */
78 	bus_space_handle_t sc_sh;	/* bus space handle */
79 	void *sc_ih;			/* interrupt cookie */
80 
81 	bus_dma_tag_t sc_dmat;		/* DMA tag */
82 
83 	bus_dmamap_t sc_xfermap;	/* DMA map for transfers */
84 
85 	u_int32_t *sc_mdladdr;		/* MDL array */
86 	bus_dmamap_t sc_mdldmap;	/* MDL DMA map */
87 
88 	int	sc_active;		/* DMA state */
89 	int	sc_datain;		/* DMA Data Direction */
90 	size_t	sc_dmasize;		/* DMA size */
91 	char	**sc_dmaaddr;		/* DMA address */
92 	size_t	*sc_dmalen;		/* DMA length */
93 };
94 
95 #define	READ_DMAREG(sc, reg) \
96 	bus_space_read_4((sc)->sc_st, (sc)->sc_sh, (reg))
97 #define	WRITE_DMAREG(sc, reg, var) \
98 	bus_space_write_4((sc)->sc_st, (sc)->sc_sh, (reg), (var))
99 
100 /* don't have to use MI defines in MD code... */
101 #undef	NCR_READ_REG
102 #define	NCR_READ_REG(sc, reg)		pcscp_read_reg((sc), (reg))
103 #undef	NCR_WRITE_REG
104 #define	NCR_WRITE_REG(sc, reg, val)	pcscp_write_reg((sc), (reg), (val))
105 
106 int	pcscp_match(struct device *, void *, void *);
107 void	pcscp_attach(struct device *, struct device *, void *);
108 
109 struct cfattach pcscp_ca = {
110 	sizeof(struct pcscp_softc), pcscp_match, pcscp_attach
111 };
112 
113 struct cfdriver pcscp_cd = {
114 	NULL, "pcscp", DV_DULL
115 };
116 
117 /*
118  * Functions and the switch for the MI code.
119  */
120 
121 u_char	pcscp_read_reg(struct ncr53c9x_softc *, int);
122 void	pcscp_write_reg(struct ncr53c9x_softc *, int, u_char);
123 int	pcscp_dma_isintr(struct ncr53c9x_softc *);
124 void	pcscp_dma_reset(struct ncr53c9x_softc *);
125 int	pcscp_dma_intr(struct ncr53c9x_softc *);
126 int	pcscp_dma_setup(struct ncr53c9x_softc *, caddr_t *,
127 			       size_t *, int, size_t *);
128 void	pcscp_dma_go(struct ncr53c9x_softc *);
129 void	pcscp_dma_stop(struct ncr53c9x_softc *);
130 int	pcscp_dma_isactive(struct ncr53c9x_softc *);
131 
132 struct scsi_adapter pcscp_adapter = {
133 	ncr53c9x_scsi_cmd,	/* cmd */
134 	minphys,		/* minphys */
135 	0,			/* open */
136 	0,			/* close */
137 };
138 
139 struct ncr53c9x_glue pcscp_glue = {
140 	pcscp_read_reg,
141 	pcscp_write_reg,
142 	pcscp_dma_isintr,
143 	pcscp_dma_reset,
144 	pcscp_dma_intr,
145 	pcscp_dma_setup,
146 	pcscp_dma_go,
147 	pcscp_dma_stop,
148 	pcscp_dma_isactive,
149 	NULL,			/* gl_clear_latched_intr */
150 };
151 
152 int
153 pcscp_match(parent, match, aux)
154 	struct device *parent;
155 	void *match, *aux;
156 {
157 	struct pci_attach_args *pa = aux;
158 	if (PCI_VENDOR(pa->pa_id) != PCI_VENDOR_AMD)
159 		return 0;
160 
161 	switch (PCI_PRODUCT(pa->pa_id)) {
162 	case PCI_PRODUCT_AMD_PCSCSI_PCI:
163 #if 0
164 	case PCI_PRODUCT_AMD_PCNETS_PCI:
165 #endif
166 		return 1;
167 	}
168 	return 0;
169 }
170 
171 /*
172  * Attach this instance, and then all the sub-devices
173  */
174 void
175 pcscp_attach(parent, self, aux)
176 	struct device *parent, *self;
177 	void *aux;
178 {
179 	struct pci_attach_args *pa = aux;
180 	struct pcscp_softc *esc = (void *)self;
181 	struct ncr53c9x_softc *sc = &esc->sc_ncr53c9x;
182 	bus_space_tag_t st, iot, memt;
183 	bus_space_handle_t sh, ioh, memh;
184 	int ioh_valid, memh_valid;
185 	pci_intr_handle_t ih;
186 	const char *intrstr;
187 	bus_dma_segment_t seg;
188 	int error, rseg;
189 
190 	ioh_valid = (pci_mapreg_map(pa, IO_MAP_REG, PCI_MAPREG_TYPE_IO, 0,
191 	    &iot, &ioh, NULL, NULL, 0) == 0);
192 #if 0	/* XXX cannot use memory map? */
193 	memh_valid = (pci_mapreg_map(pa, MEM_MAP_REG,
194 	    PCI_MAPREG_TYPE_MEM | PCI_MAPREG_MEM_TYPE_32BIT, 0,
195 	    &memt, &memh, NULL, NULL, 0) == 0);
196 #else
197 	memh_valid = 0;
198 #endif
199 
200 	if (memh_valid) {
201 		st = memt;
202 		sh = memh;
203 	} else if (ioh_valid) {
204 		st = iot;
205 		sh = ioh;
206 	} else {
207 		printf(": unable to map registers\n");
208 		return;
209 	}
210 
211 	sc->sc_glue = &pcscp_glue;
212 
213 	esc->sc_st = st;
214 	esc->sc_sh = sh;
215 	esc->sc_dmat = pa->pa_dmat;
216 
217 	/*
218 	 * XXX More of this should be in ncr53c9x_attach(), but
219 	 * XXX should we really poke around the chip that much in
220 	 * XXX the MI code?  Think about this more...
221 	 */
222 
223 	/*
224 	 * Set up static configuration info.
225 	 */
226 
227 	/*
228 	 * XXX should read configuration from EEPROM?
229 	 *
230 	 * MI ncr53c9x driver does not support configuration
231 	 * per each target device, though...
232 	 */
233 	sc->sc_id = 7;
234 	sc->sc_cfg1 = sc->sc_id | NCRCFG1_PARENB;
235 	sc->sc_cfg2 = NCRCFG2_SCSI2 | NCRCFG2_FE;
236 	sc->sc_cfg3 = NCRAMDCFG3_IDM | NCRAMDCFG3_FCLK;
237 	sc->sc_cfg4 = NCRAMDCFG4_GE12NS | NCRAMDCFG4_RADE;
238 	sc->sc_rev = NCR_VARIANT_AM53C974;
239 	sc->sc_features = NCR_F_FASTSCSI;
240 	sc->sc_cfg3_fscsi = NCRAMDCFG3_FSCSI;
241 	sc->sc_freq = 40; /* MHz */
242 
243 	/*
244 	 * XXX minsync and maxxfer _should_ be set up in MI code,
245 	 * XXX but it appears to have some dependency on what sort
246 	 * XXX of DMA we're hooked up to, etc.
247 	 */
248 
249 	/*
250 	 * This is the value used to start sync negotiations
251 	 * Note that the NCR register "SYNCTP" is programmed
252 	 * in "clocks per byte", and has a minimum value of 4.
253 	 * The SCSI period used in negotiation is one-fourth
254 	 * of the time (in nanoseconds) needed to transfer one byte.
255 	 * Since the chip's clock is given in MHz, we have the following
256 	 * formula: 4 * period = (1000 / freq) * 4
257 	 */
258 
259 	sc->sc_minsync = 1000 / sc->sc_freq;
260 
261 	/* Really no limit, but since we want to fit into the TCR... */
262 	sc->sc_maxxfer = 16 * 1024 * 1024;
263 
264 	/* map and establish interrupt */
265 	if (pci_intr_map(pa, &ih)) {
266 		printf(": couldn't map interrupt\n");
267 		return;
268 	}
269 
270 	intrstr = pci_intr_string(pa->pa_pc, ih);
271 	esc->sc_ih = pci_intr_establish(pa->pa_pc, ih, IPL_BIO,
272 	    ncr53c9x_intr, esc, sc->sc_dev.dv_xname);
273 	if (esc->sc_ih == NULL) {
274 		printf(": couldn't establish interrupt");
275 		if (intrstr != NULL)
276 			printf(" at %s", intrstr);
277 		printf("\n");
278 		return;
279 	}
280 	if (intrstr != NULL)
281 		printf(": %s\n", intrstr);
282 
283 	/*
284 	 * Create the DMA maps for the data transfers.
285          */
286 
287 #define MDL_SEG_SIZE	0x1000 /* 4kbyte per segment */
288 #define MDL_SEG_OFFSET	0x0FFF
289 #define MDL_SIZE	(MAXPHYS / MDL_SEG_SIZE + 1) /* no hardware limit? */
290 
291 	if (bus_dmamap_create(esc->sc_dmat, MAXPHYS, MDL_SIZE, MAXPHYS, 0,
292 	    BUS_DMA_NOWAIT, &esc->sc_xfermap)) {
293 		printf("%s: can't create dma maps\n", sc->sc_dev.dv_xname);
294 		return;
295 	}
296 
297 	/*
298 	 * Allocate and map memory for the MDL.
299 	 */
300 
301 	if ((error = bus_dmamem_alloc(esc->sc_dmat,
302 	    sizeof(u_int32_t) * MDL_SIZE, PAGE_SIZE, 0, &seg, 1, &rseg,
303 	    BUS_DMA_NOWAIT)) != 0) {
304 		printf("%s: unable to allocate memory for the MDL, "
305 		    "error = %d\n", sc->sc_dev.dv_xname, error);
306 		return;
307 	}
308 	if ((error = bus_dmamem_map(esc->sc_dmat, &seg, rseg,
309 	    sizeof(u_int32_t) * MDL_SIZE , (caddr_t *)&esc->sc_mdladdr,
310 	    BUS_DMA_NOWAIT|BUS_DMA_COHERENT)) != 0) {
311 		printf("%s: unable to map the MDL memory, error = %d\n",
312 		    sc->sc_dev.dv_xname, error);
313 		return;
314 	}
315 	if ((error = bus_dmamap_create(esc->sc_dmat,
316 	    sizeof(u_int32_t) * MDL_SIZE, 1, sizeof(u_int32_t) * MDL_SIZE,
317 	    0, BUS_DMA_NOWAIT, &esc->sc_mdldmap)) != 0) {
318 		printf("%s: unable to map_create for the MDL, error = %d\n",
319 		    sc->sc_dev.dv_xname, error);
320 		return;
321 	}
322 	if ((error = bus_dmamap_load(esc->sc_dmat, esc->sc_mdldmap,
323 	     esc->sc_mdladdr, sizeof(u_int32_t) * MDL_SIZE,
324 	     NULL, BUS_DMA_NOWAIT)) != 0) {
325 		printf("%s: unable to load for the MDL, error = %d\n",
326 		    sc->sc_dev.dv_xname, error);
327 		return;
328 	}
329 
330 	/* Do the common parts of attachment. */
331 	printf("%s", sc->sc_dev.dv_xname);
332 
333 	ncr53c9x_attach(sc, &pcscp_adapter, NULL);
334 
335 	/* Turn on target selection using the `dma' method */
336 	sc->sc_features |= NCR_F_DMASELECT;
337 }
338 
339 /*
340  * Glue functions.
341  */
342 
343 u_char
344 pcscp_read_reg(sc, reg)
345 	struct ncr53c9x_softc *sc;
346 	int reg;
347 {
348 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
349 
350 	return bus_space_read_1(esc->sc_st, esc->sc_sh, reg << 2);
351 }
352 
353 void
354 pcscp_write_reg(sc, reg, v)
355 	struct ncr53c9x_softc *sc;
356 	int reg;
357 	u_char v;
358 {
359 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
360 
361 	bus_space_write_1(esc->sc_st, esc->sc_sh, reg << 2, v);
362 }
363 
364 int
365 pcscp_dma_isintr(sc)
366 	struct ncr53c9x_softc *sc;
367 {
368 
369 	return NCR_READ_REG(sc, NCR_STAT) & NCRSTAT_INT;
370 }
371 
372 void
373 pcscp_dma_reset(sc)
374 	struct ncr53c9x_softc *sc;
375 {
376 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
377 
378 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_IDLE);
379 
380 	esc->sc_active = 0;
381 }
382 
383 int
384 pcscp_dma_intr(sc)
385 	struct ncr53c9x_softc *sc;
386 {
387 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
388 	int trans, resid, i;
389 	bus_dmamap_t dmap = esc->sc_xfermap;
390 	int datain = esc->sc_datain;
391 	u_int32_t dmastat;
392 	char *p = NULL;
393 
394 	dmastat = READ_DMAREG(esc, DMA_STAT);
395 
396 	if (dmastat & DMASTAT_ERR) {
397 		/* XXX not tested... */
398 		WRITE_DMAREG(esc, DMA_CMD,
399 		    DMACMD_ABORT | (datain ? DMACMD_DIR : 0));
400 
401 		printf("%s: error: DMA error detected; Aborting.\n",
402 		    sc->sc_dev.dv_xname);
403 		bus_dmamap_unload(esc->sc_dmat, dmap);
404 		return -1;
405 	}
406 
407 	if (dmastat & DMASTAT_ABT) {
408 		/* XXX What should be done? */
409 		printf("%s: dma_intr: DMA aborted.\n", sc->sc_dev.dv_xname);
410 		WRITE_DMAREG(esc, DMA_CMD,
411 		    DMACMD_IDLE | (datain ? DMACMD_DIR : 0));
412 		esc->sc_active = 0;
413 		return 0;
414 	}
415 
416 	/* This is an "assertion" :) */
417 	if (esc->sc_active == 0)
418 		panic("pcscp dmaintr: DMA wasn't active");
419 
420 	/* DMA has stopped */
421 
422 	esc->sc_active = 0;
423 
424 	if (esc->sc_dmasize == 0) {
425 		/* A "Transfer Pad" operation completed */
426 		NCR_DMA(("dmaintr: discarded %d bytes (tcl=%d, tcm=%d)\n",
427 		    NCR_READ_REG(sc, NCR_TCL) |
428 		    (NCR_READ_REG(sc, NCR_TCM) << 8),
429 		    NCR_READ_REG(sc, NCR_TCL),
430 		    NCR_READ_REG(sc, NCR_TCM)));
431 		return 0;
432 	}
433 
434 	resid = 0;
435 	/*
436 	 * If a transfer onto the SCSI bus gets interrupted by the device
437 	 * (e.g. for a SAVEPOINTER message), the data in the FIFO counts
438 	 * as residual since the ESP counter registers get decremented as
439 	 * bytes are clocked into the FIFO.
440 	 */
441 	if (!datain &&
442 	    (resid = (NCR_READ_REG(sc, NCR_FFLAG) & NCRFIFO_FF)) != 0) {
443 		NCR_DMA(("pcscp_dma_intr: empty esp FIFO of %d ", resid));
444 	}
445 
446 	if ((sc->sc_espstat & NCRSTAT_TC) == 0) {
447 		/*
448 		 * `Terminal count' is off, so read the residue
449 		 * out of the ESP counter registers.
450 		 */
451 		if (datain) {
452 			resid = NCR_READ_REG(sc, NCR_FFLAG) & NCRFIFO_FF;
453 			while (resid > 1)
454 				resid =
455 				    NCR_READ_REG(sc, NCR_FFLAG) & NCRFIFO_FF;
456 			WRITE_DMAREG(esc, DMA_CMD, DMACMD_BLAST | DMACMD_MDL |
457 			    (datain ? DMACMD_DIR : 0));
458 
459 			for (i = 0; i < 0x8000; i++) /* XXX 0x8000 ? */
460 				if (READ_DMAREG(esc, DMA_STAT) & DMASTAT_BCMP)
461 					break;
462 
463 			/* See the below comments... */
464 			if (resid)
465 				p = *esc->sc_dmaaddr;
466 		}
467 
468 		resid += (NCR_READ_REG(sc, NCR_TCL) |
469 		    (NCR_READ_REG(sc, NCR_TCM) << 8) |
470 		    ((sc->sc_cfg2 & NCRCFG2_FE)
471 		    ? (NCR_READ_REG(sc, NCR_TCH) << 16) : 0));
472 
473 		if (resid == 0 && esc->sc_dmasize == 65536 &&
474 		    (sc->sc_cfg2 & NCRCFG2_FE) == 0)
475 			/* A transfer of 64K is encoded as `TCL=TCM=0' */
476 			resid = 65536;
477 	} else {
478 		while((dmastat & DMASTAT_DONE) == 0)
479 			dmastat = READ_DMAREG(esc, DMA_STAT);
480 	}
481 
482 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_IDLE | (datain ? DMACMD_DIR : 0));
483 
484 	bus_dmamap_sync(esc->sc_dmat, dmap, 0, dmap->dm_mapsize,
485 	    datain ? BUS_DMASYNC_POSTREAD : BUS_DMASYNC_POSTWRITE);
486 	bus_dmamap_unload(esc->sc_dmat, dmap);
487 
488 	trans = esc->sc_dmasize - resid;
489 
490 	/*
491 	 * From the technical manual notes:
492 	 *
493 	 * `In some odd byte conditions, one residual byte will be left
494 	 *  in the SCSI FIFO, and the FIFO flags will never count to 0.
495 	 *  When this happens, the residual byte should be retrieved
496 	 *  via PIO following completion of the BLAST operation.'
497 	 */
498 
499 	if (p) {
500 		p += trans;
501 		*p = NCR_READ_REG(sc, NCR_FIFO);
502 		trans++;
503 	}
504 
505 	if (trans < 0) {			/* transferred < 0 ? */
506 #if 0
507 		/*
508 		 * This situation can happen in perfectly normal operation
509 		 * if the ESP is reselected while using DMA to select
510 		 * another target.  As such, don't print the warning.
511 		 */
512 		printf("%s: xfer (%d) > req (%d)\n",
513 		    sc->sc_dev.dv_xname, trans, esc->sc_dmasize);
514 #endif
515 		trans = esc->sc_dmasize;
516 	}
517 
518 	NCR_DMA(("dmaintr: tcl=%d, tcm=%d, tch=%d; trans=%d, resid=%d\n",
519 	    NCR_READ_REG(sc, NCR_TCL),
520 	    NCR_READ_REG(sc, NCR_TCM),
521 	    (sc->sc_cfg2 & NCRCFG2_FE) ? NCR_READ_REG(sc, NCR_TCH) : 0,
522 	    trans, resid));
523 
524 	*esc->sc_dmalen -= trans;
525 	*esc->sc_dmaaddr += trans;
526 
527 	return 0;
528 }
529 
530 int
531 pcscp_dma_setup(sc, addr, len, datain, dmasize)
532 	struct ncr53c9x_softc *sc;
533 	caddr_t *addr;
534 	size_t *len;
535 	int datain;
536 	size_t *dmasize;
537 {
538 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
539 	bus_dmamap_t dmap = esc->sc_xfermap;
540 	u_int32_t *mdl;
541 	int error, nseg, seg;
542 	bus_addr_t s_offset, s_addr;
543 	long rest, count;
544 
545 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_IDLE | (datain ? DMACMD_DIR : 0));
546 
547 	esc->sc_dmaaddr = addr;
548 	esc->sc_dmalen = len;
549 	esc->sc_dmasize = *dmasize;
550 	esc->sc_datain = datain;
551 
552 #ifdef DIAGNOSTIC
553 	if ((*dmasize / MDL_SEG_SIZE) > MDL_SIZE)
554 		panic("pcscp: transfer size too large");
555 #endif
556 
557 	/*
558 	 * No need to set up DMA in `Transfer Pad' operation.
559 	 * (case of *dmasize == 0)
560 	 */
561 	if (*dmasize == 0)
562 		return 0;
563 
564 	error = bus_dmamap_load(esc->sc_dmat, dmap, *esc->sc_dmaaddr,
565 	    *esc->sc_dmalen, NULL,
566 	    sc->sc_nexus->xs->flags & SCSI_NOSLEEP ?
567 	    BUS_DMA_NOWAIT : BUS_DMA_WAITOK);
568 	if (error) {
569 		printf("%s: unable to load dmamap, error = %d\n",
570 		    sc->sc_dev.dv_xname, error);
571 		return error;
572 	}
573 
574 	/* set transfer length */
575 	WRITE_DMAREG(esc, DMA_STC, *dmasize);
576 
577 	/* set up MDL */
578 	mdl = esc->sc_mdladdr;
579 	nseg = dmap->dm_nsegs;
580 
581 	/* the first segment is possibly not aligned with 4k MDL boundary */
582 	count = dmap->dm_segs[0].ds_len;
583 	s_addr = dmap->dm_segs[0].ds_addr;
584 	s_offset = s_addr & MDL_SEG_OFFSET;
585 	s_addr -= s_offset;
586 	rest = MDL_SEG_SIZE - s_offset;
587 
588 	/* set the first MDL and offset */
589 	WRITE_DMAREG(esc, DMA_SPA, s_offset);
590 	*mdl++ = htole32(s_addr);
591 	count -= rest;
592 
593 	/* rests of the first dmamap segment */
594 	while (count > 0) {
595 		s_addr += MDL_SEG_SIZE;
596 		*mdl++ = htole32(s_addr);
597 		count -= MDL_SEG_SIZE;
598 	}
599 
600 	/* the rest dmamap segments are aligned with 4k boundary */
601 	for (seg = 1; seg < nseg; seg++) {
602 		count = dmap->dm_segs[seg].ds_len;
603 		s_addr = dmap->dm_segs[seg].ds_addr;
604 
605 		/* first 4kbyte of each dmamap segment */
606 		*mdl++ = htole32(s_addr);
607 		count -= MDL_SEG_SIZE;
608 
609 		/* trailing contiguous 4k frames of each dmamap segments */
610 		while (count > 0) {
611 			s_addr += MDL_SEG_SIZE;
612 			*mdl++ = htole32(s_addr);
613 			count -= MDL_SEG_SIZE;
614 		}
615 	}
616 
617 	return 0;
618 }
619 
620 void
621 pcscp_dma_go(sc)
622 	struct ncr53c9x_softc *sc;
623 {
624 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
625 	bus_dmamap_t dmap = esc->sc_xfermap, mdldmap = esc->sc_mdldmap;
626 	int datain = esc->sc_datain;
627 
628 	/* No DMA transfer in Transfer Pad operation */
629 	if (esc->sc_dmasize == 0)
630 		return;
631 
632 	/* sync transfer buffer */
633 	bus_dmamap_sync(esc->sc_dmat, dmap, 0, dmap->dm_mapsize,
634 	    datain ? BUS_DMASYNC_PREREAD : BUS_DMASYNC_PREWRITE);
635 
636 	/* sync MDL */
637 	bus_dmamap_sync(esc->sc_dmat, mdldmap, 0, mdldmap->dm_mapsize,
638 	    BUS_DMASYNC_PREWRITE);
639 
640 	/* set Starting MDL Address */
641 	WRITE_DMAREG(esc, DMA_SMDLA, mdldmap->dm_segs[0].ds_addr);
642 
643 	/* set DMA command register bits */
644 	/* XXX DMA Transfer Interrupt Enable bit is broken? */
645 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_IDLE | DMACMD_MDL |
646 	    /* DMACMD_INTE | */
647 	    (datain ? DMACMD_DIR : 0));
648 
649 	/* issue DMA start command */
650 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_START | DMACMD_MDL |
651 	    /* DMACMD_INTE | */
652 	    (datain ? DMACMD_DIR : 0));
653 
654 	esc->sc_active = 1;
655 }
656 
657 void
658 pcscp_dma_stop(sc)
659 	struct ncr53c9x_softc *sc;
660 {
661 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
662 
663 	/* dma stop */
664 	/* XXX What should we do here ? */
665 	WRITE_DMAREG(esc, DMA_CMD,
666 	    DMACMD_ABORT | (esc->sc_datain ? DMACMD_DIR : 0));
667 
668 	esc->sc_active = 0;
669 }
670 
671 int
672 pcscp_dma_isactive(sc)
673 	struct ncr53c9x_softc *sc;
674 {
675 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
676 
677 	/* XXX should check esc->sc_active? */
678 	if ((READ_DMAREG(esc, DMA_CMD) & DMACMD_CMD) != DMACMD_IDLE)
679 		return 1;
680 	return 0;
681 }
682