xref: /netbsd/sys/dev/pci/pcscp.c (revision bf9ec67e)
1 /*	$NetBSD: pcscp.c,v 1.17 2001/11/13 07:48:48 lukem Exp $	*/
2 
3 /*-
4  * Copyright (c) 1997, 1998, 1999 The NetBSD Foundation, Inc.
5  * All rights reserved.
6  *
7  * This code is derived from software contributed to The NetBSD Foundation
8  * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
9  * NASA Ames Research Center; Izumi Tsutsui.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions and the following disclaimer.
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in the
18  *    documentation and/or other materials provided with the distribution.
19  * 3. All advertising materials mentioning features or use of this software
20  *    must display the following acknowledgement:
21  *	This product includes software developed by the NetBSD
22  *	Foundation, Inc. and its contributors.
23  * 4. Neither the name of The NetBSD Foundation nor the names of its
24  *    contributors may be used to endorse or promote products derived
25  *    from this software without specific prior written permission.
26  *
27  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
28  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
29  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
30  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
31  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
32  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
33  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
34  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
35  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
36  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
37  * POSSIBILITY OF SUCH DAMAGE.
38  */
39 
40 /*
41  * pcscp.c: device dependent code for AMD Am53c974 (PCscsi-PCI)
42  * written by Izumi Tsutsui <tsutsui@ceres.dti.ne.jp>
43  *
44  * Technical manual available at
45  * http://www.amd.com/products/npd/techdocs/techdocs.html
46  */
47 
48 #include <sys/cdefs.h>
49 __KERNEL_RCSID(0, "$NetBSD: pcscp.c,v 1.17 2001/11/13 07:48:48 lukem Exp $");
50 
51 #include <sys/param.h>
52 #include <sys/systm.h>
53 #include <sys/device.h>
54 #include <sys/buf.h>
55 
56 #include <machine/bus.h>
57 #include <machine/intr.h>
58 #include <machine/endian.h>
59 
60 #include <uvm/uvm_extern.h>
61 
62 #include <dev/scsipi/scsipi_all.h>
63 #include <dev/scsipi/scsi_all.h>
64 #include <dev/scsipi/scsiconf.h>
65 
66 #include <dev/pci/pcireg.h>
67 #include <dev/pci/pcivar.h>
68 #include <dev/pci/pcidevs.h>
69 
70 #include <dev/ic/ncr53c9xreg.h>
71 #include <dev/ic/ncr53c9xvar.h>
72 
73 #include <dev/pci/pcscpreg.h>
74 
75 #define IO_MAP_REG	0x10
76 #define MEM_MAP_REG	0x14
77 
78 struct pcscp_softc {
79 	struct ncr53c9x_softc sc_ncr53c9x;	/* glue to MI code */
80 
81 	bus_space_tag_t sc_st;		/* bus space tag */
82 	bus_space_handle_t sc_sh;	/* bus space handle */
83 	void *sc_ih;			/* interrupt cookie */
84 
85 	bus_dma_tag_t sc_dmat;		/* DMA tag */
86 
87 	bus_dmamap_t sc_xfermap;	/* DMA map for transfers */
88 
89 	u_int32_t *sc_mdladdr;		/* MDL array */
90 	bus_dmamap_t sc_mdldmap;	/* MDL DMA map */
91 
92 	int	sc_active;		/* DMA state */
93 	int	sc_datain;		/* DMA Data Direction */
94 	size_t	sc_dmasize;		/* DMA size */
95 	char	**sc_dmaaddr;		/* DMA address */
96 	size_t	*sc_dmalen;		/* DMA length */
97 };
98 
99 #define	READ_DMAREG(sc, reg) \
100 	bus_space_read_4((sc)->sc_st, (sc)->sc_sh, (reg))
101 #define	WRITE_DMAREG(sc, reg, var) \
102 	bus_space_write_4((sc)->sc_st, (sc)->sc_sh, (reg), (var))
103 
104 /* don't have to use MI defines in MD code... */
105 #undef	NCR_READ_REG
106 #define	NCR_READ_REG(sc, reg)		pcscp_read_reg((sc), (reg))
107 #undef	NCR_WRITE_REG
108 #define	NCR_WRITE_REG(sc, reg, val)	pcscp_write_reg((sc), (reg), (val))
109 
110 int	pcscp_match __P((struct device *, struct cfdata *, void *));
111 void	pcscp_attach __P((struct device *, struct device *, void *));
112 
113 struct cfattach pcscp_ca = {
114 	sizeof(struct pcscp_softc), pcscp_match, pcscp_attach
115 };
116 
117 /*
118  * Functions and the switch for the MI code.
119  */
120 
121 u_char	pcscp_read_reg __P((struct ncr53c9x_softc *, int));
122 void	pcscp_write_reg __P((struct ncr53c9x_softc *, int, u_char));
123 int	pcscp_dma_isintr __P((struct ncr53c9x_softc *));
124 void	pcscp_dma_reset __P((struct ncr53c9x_softc *));
125 int	pcscp_dma_intr __P((struct ncr53c9x_softc *));
126 int	pcscp_dma_setup __P((struct ncr53c9x_softc *, caddr_t *,
127 			       size_t *, int, size_t *));
128 void	pcscp_dma_go __P((struct ncr53c9x_softc *));
129 void	pcscp_dma_stop __P((struct ncr53c9x_softc *));
130 int	pcscp_dma_isactive __P((struct ncr53c9x_softc *));
131 
132 struct ncr53c9x_glue pcscp_glue = {
133 	pcscp_read_reg,
134 	pcscp_write_reg,
135 	pcscp_dma_isintr,
136 	pcscp_dma_reset,
137 	pcscp_dma_intr,
138 	pcscp_dma_setup,
139 	pcscp_dma_go,
140 	pcscp_dma_stop,
141 	pcscp_dma_isactive,
142 	NULL,			/* gl_clear_latched_intr */
143 };
144 
145 int
146 pcscp_match(parent, match, aux)
147 	struct device *parent;
148 	struct cfdata *match;
149 	void *aux;
150 {
151 	struct pci_attach_args *pa = aux;
152 	if (PCI_VENDOR(pa->pa_id) != PCI_VENDOR_AMD)
153 		return 0;
154 
155 	switch (PCI_PRODUCT(pa->pa_id)) {
156 	case PCI_PRODUCT_AMD_PCSCSI_PCI:
157 #if 0
158 	case PCI_PRODUCT_AMD_PCNETS_PCI:
159 #endif
160 		return 1;
161 	}
162 	return 0;
163 }
164 
165 /*
166  * Attach this instance, and then all the sub-devices
167  */
168 void
169 pcscp_attach(parent, self, aux)
170 	struct device *parent, *self;
171 	void *aux;
172 {
173 	struct pci_attach_args *pa = aux;
174 	struct pcscp_softc *esc = (void *)self;
175 	struct ncr53c9x_softc *sc = &esc->sc_ncr53c9x;
176 	bus_space_tag_t st, iot, memt;
177 	bus_space_handle_t sh, ioh, memh;
178 	int ioh_valid, memh_valid;
179 	pci_intr_handle_t ih;
180 	const char *intrstr;
181 	pcireg_t csr;
182 	bus_dma_segment_t seg;
183 	int error, rseg;
184 
185 	ioh_valid = (pci_mapreg_map(pa, IO_MAP_REG,
186 	    PCI_MAPREG_TYPE_IO, 0,
187 	    &iot, &ioh, NULL, NULL) == 0);
188 #if 0	/* XXX cannot use memory map? */
189 	memh_valid = (pci_mapreg_map(pa, MEM_MAP_REG,
190 	    PCI_MAPREG_TYPE_MEM | PCI_MAPREG_MEM_TYPE_32BIT, 0,
191 	    &memt, &memh, NULL, NULL) == 0);
192 #else
193 	memh_valid = 0;
194 #endif
195 
196 	if (memh_valid) {
197 		st = memt;
198 		sh = memh;
199 	} else if (ioh_valid) {
200 		st = iot;
201 		sh = ioh;
202 	} else {
203 		printf(": unable to map registers\n");
204 		return;
205 	}
206 	printf("\n");
207 
208 	sc->sc_glue = &pcscp_glue;
209 
210 	esc->sc_st = st;
211 	esc->sc_sh = sh;
212 	esc->sc_dmat = pa->pa_dmat;
213 
214 	csr = pci_conf_read(pa->pa_pc, pa->pa_tag, PCI_COMMAND_STATUS_REG);
215 	pci_conf_write(pa->pa_pc, pa->pa_tag, PCI_COMMAND_STATUS_REG,
216 	    csr | PCI_COMMAND_MASTER_ENABLE | PCI_COMMAND_IO_ENABLE);
217 
218 	/*
219 	 * XXX More of this should be in ncr53c9x_attach(), but
220 	 * XXX should we really poke around the chip that much in
221 	 * XXX the MI code?  Think about this more...
222 	 */
223 
224 	/*
225 	 * Set up static configuration info.
226 	 */
227 
228 	/*
229 	 * XXX should read configuration from EEPROM?
230 	 *
231 	 * MI ncr53c9x driver does not support configuration
232 	 * per each target device, though...
233 	 */
234 	sc->sc_id = 7;
235 	sc->sc_cfg1 = sc->sc_id | NCRCFG1_PARENB;
236 	sc->sc_cfg2 = NCRCFG2_SCSI2 | NCRCFG2_FE;
237 	sc->sc_cfg3 = NCRAMDCFG3_IDM | NCRAMDCFG3_FCLK;
238 	sc->sc_cfg4 = NCRAMDCFG4_GE12NS | NCRAMDCFG4_RADE;
239 	sc->sc_rev = NCR_VARIANT_AM53C974;
240 	sc->sc_features = NCR_F_FASTSCSI;
241 	sc->sc_cfg3_fscsi = NCRAMDCFG3_FSCSI;
242 	sc->sc_freq = 40; /* MHz */
243 
244 	/*
245 	 * XXX minsync and maxxfer _should_ be set up in MI code,
246 	 * XXX but it appears to have some dependency on what sort
247 	 * XXX of DMA we're hooked up to, etc.
248 	 */
249 
250 	/*
251 	 * This is the value used to start sync negotiations
252 	 * Note that the NCR register "SYNCTP" is programmed
253 	 * in "clocks per byte", and has a minimum value of 4.
254 	 * The SCSI period used in negotiation is one-fourth
255 	 * of the time (in nanoseconds) needed to transfer one byte.
256 	 * Since the chip's clock is given in MHz, we have the following
257 	 * formula: 4 * period = (1000 / freq) * 4
258 	 */
259 
260 	sc->sc_minsync = 1000 / sc->sc_freq;
261 
262 	/* Really no limit, but since we want to fit into the TCR... */
263 	sc->sc_maxxfer = 16 * 1024 * 1024;
264 
265 	/* map and establish interrupt */
266 	if (pci_intr_map(pa, &ih)) {
267 		printf("%s: couldn't map interrupt\n", sc->sc_dev.dv_xname);
268 		return;
269 	}
270 
271 	intrstr = pci_intr_string(pa->pa_pc, ih);
272 	esc->sc_ih = pci_intr_establish(pa->pa_pc, ih, IPL_BIO,
273 	    ncr53c9x_intr, esc);
274 	if (esc->sc_ih == NULL) {
275 		printf("%s: couldn't establish interrupt", sc->sc_dev.dv_xname);
276 		if (intrstr != NULL)
277 			printf(" at %s", intrstr);
278 		printf("\n");
279 		return;
280 	}
281 	if (intrstr != NULL)
282 		printf("%s: interrupting at %s\n", sc->sc_dev.dv_xname,
283 		    intrstr);
284 
285 	/*
286 	 * Create the DMA maps for the data transfers.
287          */
288 
289 #define MDL_SEG_SIZE	0x1000 /* 4kbyte per segment */
290 #define MDL_SEG_OFFSET	0x0FFF
291 #define MDL_SIZE	(MAXPHYS / MDL_SEG_SIZE + 1) /* no hardware limit? */
292 
293 	if (bus_dmamap_create(esc->sc_dmat, MAXPHYS, MDL_SIZE, MAXPHYS, 0,
294 	    BUS_DMA_NOWAIT, &esc->sc_xfermap)) {
295 		printf("%s: can't create dma maps\n", sc->sc_dev.dv_xname);
296 		return;
297 	}
298 
299 	/*
300 	 * Allocate and map memory for the MDL.
301 	 */
302 
303 	if ((error = bus_dmamem_alloc(esc->sc_dmat,
304 	    sizeof(u_int32_t) * MDL_SIZE, PAGE_SIZE, 0, &seg, 1, &rseg,
305 	    BUS_DMA_NOWAIT)) != 0) {
306 		printf("%s: unable to allocate memory for the MDL, "
307 		    "error = %d\n", sc->sc_dev.dv_xname, error);
308 		return;
309 	}
310 	if ((error = bus_dmamem_map(esc->sc_dmat, &seg, rseg,
311 	    sizeof(u_int32_t) * MDL_SIZE , (caddr_t *)&esc->sc_mdladdr,
312 	    BUS_DMA_NOWAIT|BUS_DMA_COHERENT)) != 0) {
313 		printf("%s: unable to map the MDL memory, error = %d\n",
314 		    sc->sc_dev.dv_xname, error);
315 		return;
316 	}
317 	if ((error = bus_dmamap_create(esc->sc_dmat,
318 	    sizeof(u_int32_t) * MDL_SIZE, 1, sizeof(u_int32_t) * MDL_SIZE,
319 	    0, BUS_DMA_NOWAIT, &esc->sc_mdldmap)) != 0) {
320 		printf("%s: unable to map_create for the MDL, error = %d\n",
321 		    sc->sc_dev.dv_xname, error);
322 		return;
323 	}
324 	if ((error = bus_dmamap_load(esc->sc_dmat, esc->sc_mdldmap,
325 	     esc->sc_mdladdr, sizeof(u_int32_t) * MDL_SIZE,
326 	     NULL, BUS_DMA_NOWAIT)) != 0) {
327 		printf("%s: unable to load for the MDL, error = %d\n",
328 		    sc->sc_dev.dv_xname, error);
329 		return;
330 	}
331 
332 	/* Do the common parts of attachment. */
333 	printf("%s", sc->sc_dev.dv_xname);
334 
335 	sc->sc_adapter.adapt_minphys = minphys;
336 	sc->sc_adapter.adapt_request = ncr53c9x_scsipi_request;
337 	ncr53c9x_attach(sc);
338 
339 	/* Turn on target selection using the `dma' method */
340 	sc->sc_features |= NCR_F_DMASELECT;
341 }
342 
343 /*
344  * Glue functions.
345  */
346 
347 u_char
348 pcscp_read_reg(sc, reg)
349 	struct ncr53c9x_softc *sc;
350 	int reg;
351 {
352 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
353 
354 	return bus_space_read_1(esc->sc_st, esc->sc_sh, reg << 2);
355 }
356 
357 void
358 pcscp_write_reg(sc, reg, v)
359 	struct ncr53c9x_softc *sc;
360 	int reg;
361 	u_char v;
362 {
363 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
364 
365 	bus_space_write_1(esc->sc_st, esc->sc_sh, reg << 2, v);
366 }
367 
368 int
369 pcscp_dma_isintr(sc)
370 	struct ncr53c9x_softc *sc;
371 {
372 
373 	return NCR_READ_REG(sc, NCR_STAT) & NCRSTAT_INT;
374 }
375 
376 void
377 pcscp_dma_reset(sc)
378 	struct ncr53c9x_softc *sc;
379 {
380 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
381 
382 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_IDLE);
383 
384 	esc->sc_active = 0;
385 }
386 
387 int
388 pcscp_dma_intr(sc)
389 	struct ncr53c9x_softc *sc;
390 {
391 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
392 	int trans, resid, i;
393 	bus_dmamap_t dmap = esc->sc_xfermap;
394 	int datain = esc->sc_datain;
395 	u_int32_t dmastat;
396 	char *p = NULL;
397 
398 	dmastat = READ_DMAREG(esc, DMA_STAT);
399 
400 	if (dmastat & DMASTAT_ERR) {
401 		/* XXX not tested... */
402 		WRITE_DMAREG(esc, DMA_CMD,
403 		    DMACMD_ABORT | (datain ? DMACMD_DIR : 0));
404 
405 		printf("%s: error: DMA error detected; Aborting.\n",
406 		    sc->sc_dev.dv_xname);
407 		bus_dmamap_unload(esc->sc_dmat, dmap);
408 		return -1;
409 	}
410 
411 	if (dmastat & DMASTAT_ABT) {
412 		/* XXX What should be done? */
413 		printf("%s: dma_intr: DMA aborted.\n", sc->sc_dev.dv_xname);
414 		WRITE_DMAREG(esc, DMA_CMD,
415 		    DMACMD_IDLE | (datain ? DMACMD_DIR : 0));
416 		esc->sc_active = 0;
417 		return 0;
418 	}
419 
420 	/* This is an "assertion" :) */
421 	if (esc->sc_active == 0)
422 		panic("pcscp dmaintr: DMA wasn't active");
423 
424 	/* DMA has stopped */
425 
426 	esc->sc_active = 0;
427 
428 	if (esc->sc_dmasize == 0) {
429 		/* A "Transfer Pad" operation completed */
430 		NCR_DMA(("dmaintr: discarded %d bytes (tcl=%d, tcm=%d)\n",
431 		    NCR_READ_REG(sc, NCR_TCL) |
432 		    (NCR_READ_REG(sc, NCR_TCM) << 8),
433 		    NCR_READ_REG(sc, NCR_TCL),
434 		    NCR_READ_REG(sc, NCR_TCM)));
435 		return 0;
436 	}
437 
438 	resid = 0;
439 	/*
440 	 * If a transfer onto the SCSI bus gets interrupted by the device
441 	 * (e.g. for a SAVEPOINTER message), the data in the FIFO counts
442 	 * as residual since the ESP counter registers get decremented as
443 	 * bytes are clocked into the FIFO.
444 	 */
445 	if (!datain &&
446 	    (resid = (NCR_READ_REG(sc, NCR_FFLAG) & NCRFIFO_FF)) != 0) {
447 		NCR_DMA(("pcscp_dma_intr: empty esp FIFO of %d ", resid));
448 	}
449 
450 	if ((sc->sc_espstat & NCRSTAT_TC) == 0) {
451 		/*
452 		 * `Terminal count' is off, so read the residue
453 		 * out of the ESP counter registers.
454 		 */
455 		if (datain) {
456 			resid = NCR_READ_REG(sc, NCR_FFLAG) & NCRFIFO_FF;
457 			while (resid > 1)
458 				resid =
459 				    NCR_READ_REG(sc, NCR_FFLAG) & NCRFIFO_FF;
460 			WRITE_DMAREG(esc, DMA_CMD, DMACMD_BLAST | DMACMD_MDL |
461 			    (datain ? DMACMD_DIR : 0));
462 
463 			for (i = 0; i < 0x8000; i++) /* XXX 0x8000 ? */
464 				if (READ_DMAREG(esc, DMA_STAT) & DMASTAT_BCMP)
465 					break;
466 
467 			/* See the below comments... */
468 			if (resid)
469 				p = *esc->sc_dmaaddr;
470 		}
471 
472 		resid += (NCR_READ_REG(sc, NCR_TCL) |
473 		    (NCR_READ_REG(sc, NCR_TCM) << 8) |
474 		    ((sc->sc_cfg2 & NCRCFG2_FE)
475 		    ? (NCR_READ_REG(sc, NCR_TCH) << 16) : 0));
476 
477 		if (resid == 0 && esc->sc_dmasize == 65536 &&
478 		    (sc->sc_cfg2 & NCRCFG2_FE) == 0)
479 			/* A transfer of 64K is encoded as `TCL=TCM=0' */
480 			resid = 65536;
481 	} else {
482 		while((dmastat & DMASTAT_DONE) == 0)
483 			dmastat = READ_DMAREG(esc, DMA_STAT);
484 	}
485 
486 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_IDLE | (datain ? DMACMD_DIR : 0));
487 
488 	bus_dmamap_sync(esc->sc_dmat, dmap, 0, dmap->dm_mapsize,
489 	    datain ? BUS_DMASYNC_POSTREAD : BUS_DMASYNC_POSTWRITE);
490 	bus_dmamap_unload(esc->sc_dmat, dmap);
491 
492 	trans = esc->sc_dmasize - resid;
493 
494 	/*
495 	 * From the technical manual notes:
496 	 *
497 	 * `In some odd byte conditions, one residual byte will be left
498 	 *  in the SCSI FIFO, and the FIFO flags will never count to 0.
499 	 *  When this happens, the residual byte should be retrieved
500 	 *  via PIO following completion of the BLAST operation.'
501 	 */
502 
503 	if (p) {
504 		p += trans;
505 		*p = NCR_READ_REG(sc, NCR_FIFO);
506 		trans++;
507 	}
508 
509 	if (trans < 0) {			/* transferred < 0 ? */
510 #if 0
511 		/*
512 		 * This situation can happen in perfectly normal operation
513 		 * if the ESP is reselected while using DMA to select
514 		 * another target.  As such, don't print the warning.
515 		 */
516 		printf("%s: xfer (%d) > req (%d)\n",
517 		    sc->sc_dev.dv_xname, trans, esc->sc_dmasize);
518 #endif
519 		trans = esc->sc_dmasize;
520 	}
521 
522 	NCR_DMA(("dmaintr: tcl=%d, tcm=%d, tch=%d; trans=%d, resid=%d\n",
523 	    NCR_READ_REG(sc, NCR_TCL),
524 	    NCR_READ_REG(sc, NCR_TCM),
525 	    (sc->sc_cfg2 & NCRCFG2_FE) ? NCR_READ_REG(sc, NCR_TCH) : 0,
526 	    trans, resid));
527 
528 	*esc->sc_dmalen -= trans;
529 	*esc->sc_dmaaddr += trans;
530 
531 	return 0;
532 }
533 
534 int
535 pcscp_dma_setup(sc, addr, len, datain, dmasize)
536 	struct ncr53c9x_softc *sc;
537 	caddr_t *addr;
538 	size_t *len;
539 	int datain;
540 	size_t *dmasize;
541 {
542 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
543 	bus_dmamap_t dmap = esc->sc_xfermap;
544 	u_int32_t *mdl;
545 	int error, nseg, seg;
546 	bus_addr_t s_offset, s_addr;
547 	long rest, count;
548 
549 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_IDLE | (datain ? DMACMD_DIR : 0));
550 
551 	esc->sc_dmaaddr = addr;
552 	esc->sc_dmalen = len;
553 	esc->sc_dmasize = *dmasize;
554 	esc->sc_datain = datain;
555 
556 #ifdef DIAGNOSTIC
557 	if ((*dmasize / MDL_SEG_SIZE) > MDL_SIZE)
558 		panic("pcscp: transfer size too large");
559 #endif
560 
561 	/*
562 	 * No need to set up DMA in `Transfer Pad' operation.
563 	 * (case of *dmasize == 0)
564 	 */
565 	if (*dmasize == 0)
566 		return 0;
567 
568 	error = bus_dmamap_load(esc->sc_dmat, dmap, *esc->sc_dmaaddr,
569 	    *esc->sc_dmalen, NULL,
570 	    ((sc->sc_nexus->xs->xs_control & XS_CTL_NOSLEEP) ?
571 	    BUS_DMA_NOWAIT : BUS_DMA_WAITOK) | BUS_DMA_STREAMING |
572 	    ((sc->sc_nexus->xs->xs_control & XS_CTL_DATA_IN) ?
573 	     BUS_DMA_READ : BUS_DMA_WRITE));
574 	if (error) {
575 		printf("%s: unable to load dmamap, error = %d\n",
576 		    sc->sc_dev.dv_xname, error);
577 		return error;
578 	}
579 
580 	/* set transfer length */
581 	WRITE_DMAREG(esc, DMA_STC, *dmasize);
582 
583 	/* set up MDL */
584 	mdl = esc->sc_mdladdr;
585 	nseg = dmap->dm_nsegs;
586 
587 	/* the first segment is possibly not aligned with 4k MDL boundary */
588 	count = dmap->dm_segs[0].ds_len;
589 	s_addr = dmap->dm_segs[0].ds_addr;
590 	s_offset = s_addr & MDL_SEG_OFFSET;
591 	s_addr -= s_offset;
592 	rest = MDL_SEG_SIZE - s_offset;
593 
594 	/* set the first MDL and offset */
595 	WRITE_DMAREG(esc, DMA_SPA, s_offset);
596 	*mdl++ = htole32(s_addr);
597 	count -= rest;
598 
599 	/* rests of the first dmamap segment */
600 	while (count > 0) {
601 		s_addr += MDL_SEG_SIZE;
602 		*mdl++ = htole32(s_addr);
603 		count -= MDL_SEG_SIZE;
604 	}
605 
606 	/* the rest dmamap segments are aligned with 4k boundary */
607 	for (seg = 1; seg < nseg; seg++) {
608 		count = dmap->dm_segs[seg].ds_len;
609 		s_addr = dmap->dm_segs[seg].ds_addr;
610 
611 		/* first 4kbyte of each dmamap segment */
612 		*mdl++ = htole32(s_addr);
613 		count -= MDL_SEG_SIZE;
614 
615 		/* trailing contiguous 4k frames of each dmamap segments */
616 		while (count > 0) {
617 			s_addr += MDL_SEG_SIZE;
618 			*mdl++ = htole32(s_addr);
619 			count -= MDL_SEG_SIZE;
620 		}
621 	}
622 
623 	return 0;
624 }
625 
626 void
627 pcscp_dma_go(sc)
628 	struct ncr53c9x_softc *sc;
629 {
630 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
631 	bus_dmamap_t dmap = esc->sc_xfermap, mdldmap = esc->sc_mdldmap;
632 	int datain = esc->sc_datain;
633 
634 	/* No DMA transfer in Transfer Pad operation */
635 	if (esc->sc_dmasize == 0)
636 		return;
637 
638 	/* sync transfer buffer */
639 	bus_dmamap_sync(esc->sc_dmat, dmap, 0, dmap->dm_mapsize,
640 	    datain ? BUS_DMASYNC_PREREAD : BUS_DMASYNC_PREWRITE);
641 
642 	/* sync MDL */
643 	bus_dmamap_sync(esc->sc_dmat, mdldmap, 0, mdldmap->dm_mapsize,
644 	    BUS_DMASYNC_PREWRITE);
645 
646 	/* set Starting MDL Address */
647 	WRITE_DMAREG(esc, DMA_SMDLA, mdldmap->dm_segs[0].ds_addr);
648 
649 	/* set DMA command register bits */
650 	/* XXX DMA Transfer Interrupt Enable bit is broken? */
651 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_IDLE | DMACMD_MDL |
652 	    /* DMACMD_INTE | */
653 	    (datain ? DMACMD_DIR : 0));
654 
655 	/* issue DMA start command */
656 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_START | DMACMD_MDL |
657 	    /* DMACMD_INTE | */
658 	    (datain ? DMACMD_DIR : 0));
659 
660 	esc->sc_active = 1;
661 }
662 
663 void
664 pcscp_dma_stop(sc)
665 	struct ncr53c9x_softc *sc;
666 {
667 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
668 
669 	/* dma stop */
670 	/* XXX What should we do here ? */
671 	WRITE_DMAREG(esc, DMA_CMD,
672 	    DMACMD_ABORT | (esc->sc_datain ? DMACMD_DIR : 0));
673 
674 	esc->sc_active = 0;
675 }
676 
677 int
678 pcscp_dma_isactive(sc)
679 	struct ncr53c9x_softc *sc;
680 {
681 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
682 
683 	/* XXX should check esc->sc_active? */
684 	if ((READ_DMAREG(esc, DMA_CMD) & DMACMD_CMD) != DMACMD_IDLE)
685 		return 1;
686 	return 0;
687 }
688