xref: /netbsd-src/sys/dev/pci/pcscp.c (revision e5548b402ae4c44fb816de42c7bba9581ce23ef5)
1 /*	$NetBSD: pcscp.c,v 1.34 2005/12/11 12:22:50 christos 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/files/connectivitysolutions/networking/archivednetworking/19113.pdf
46  */
47 
48 #include <sys/cdefs.h>
49 __KERNEL_RCSID(0, "$NetBSD: pcscp.c,v 1.34 2005/12/11 12:22:50 christos 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 
59 #include <uvm/uvm_extern.h>
60 
61 #include <dev/scsipi/scsipi_all.h>
62 #include <dev/scsipi/scsi_all.h>
63 #include <dev/scsipi/scsiconf.h>
64 
65 #include <dev/pci/pcireg.h>
66 #include <dev/pci/pcivar.h>
67 #include <dev/pci/pcidevs.h>
68 
69 #include <dev/ic/ncr53c9xreg.h>
70 #include <dev/ic/ncr53c9xvar.h>
71 
72 #include <dev/pci/pcscpreg.h>
73 
74 #define IO_MAP_REG	0x10
75 
76 struct pcscp_softc {
77 	struct ncr53c9x_softc sc_ncr53c9x;	/* glue to MI code */
78 
79 	bus_space_tag_t sc_st;		/* bus space tag */
80 	bus_space_handle_t sc_sh;	/* bus space handle */
81 	void *sc_ih;			/* interrupt cookie */
82 
83 	bus_dma_tag_t sc_dmat;		/* DMA tag */
84 
85 	bus_dmamap_t sc_xfermap;	/* DMA map for transfers */
86 
87 	uint32_t *sc_mdladdr;		/* MDL array */
88 	bus_dmamap_t sc_mdldmap;	/* MDL DMA map */
89 
90 	int	sc_active;		/* DMA state */
91 	int	sc_datain;		/* DMA Data Direction */
92 	size_t	sc_dmasize;		/* DMA size */
93 	char	**sc_dmaaddr;		/* DMA address */
94 	size_t	*sc_dmalen;		/* DMA length */
95 };
96 
97 #define	READ_DMAREG(sc, reg) \
98 	bus_space_read_4((sc)->sc_st, (sc)->sc_sh, (reg))
99 #define	WRITE_DMAREG(sc, reg, var) \
100 	bus_space_write_4((sc)->sc_st, (sc)->sc_sh, (reg), (var))
101 
102 #define	PCSCP_READ_REG(sc, reg)	\
103 	bus_space_read_1((sc)->sc_st, (sc)->sc_sh, (reg) << 2)
104 #define	PCSCP_WRITE_REG(sc, reg, val)	\
105 	bus_space_write_1((sc)->sc_st, (sc)->sc_sh, (reg) << 2, (val))
106 
107 /*
108  * Functions and the switch for the MI code.
109  */
110 
111 static u_char	pcscp_read_reg(struct ncr53c9x_softc *, int);
112 static void	pcscp_write_reg(struct ncr53c9x_softc *, int, u_char);
113 static int	pcscp_dma_isintr(struct ncr53c9x_softc *);
114 static void	pcscp_dma_reset(struct ncr53c9x_softc *);
115 static int	pcscp_dma_intr(struct ncr53c9x_softc *);
116 static int	pcscp_dma_setup(struct ncr53c9x_softc *, caddr_t *, size_t *,
117 				int, size_t *);
118 static void	pcscp_dma_go(struct ncr53c9x_softc *);
119 static void	pcscp_dma_stop(struct ncr53c9x_softc *);
120 static int	pcscp_dma_isactive(struct ncr53c9x_softc *);
121 
122 static struct ncr53c9x_glue pcscp_glue = {
123 	pcscp_read_reg,
124 	pcscp_write_reg,
125 	pcscp_dma_isintr,
126 	pcscp_dma_reset,
127 	pcscp_dma_intr,
128 	pcscp_dma_setup,
129 	pcscp_dma_go,
130 	pcscp_dma_stop,
131 	pcscp_dma_isactive,
132 	NULL,			/* gl_clear_latched_intr */
133 };
134 
135 static int
136 pcscp_match(struct device *parent, struct cfdata *match, void *aux)
137 {
138 	struct pci_attach_args *pa = aux;
139 
140 	if (PCI_VENDOR(pa->pa_id) != PCI_VENDOR_AMD)
141 		return 0;
142 
143 	switch (PCI_PRODUCT(pa->pa_id)) {
144 	case PCI_PRODUCT_AMD_PCSCSI_PCI:
145 		return 1;
146 	}
147 	return 0;
148 }
149 
150 /*
151  * Attach this instance, and then all the sub-devices
152  */
153 static void
154 pcscp_attach(struct device *parent, struct device *self, void *aux)
155 {
156 	struct pci_attach_args *pa = aux;
157 	struct pcscp_softc *esc = (void *)self;
158 	struct ncr53c9x_softc *sc = &esc->sc_ncr53c9x;
159 	bus_space_tag_t iot;
160 	bus_space_handle_t ioh;
161 	pci_intr_handle_t ih;
162 	const char *intrstr;
163 	pcireg_t csr;
164 	bus_dma_segment_t seg;
165 	int error, rseg;
166 	char devinfo[256];
167 
168 	pci_devinfo(pa->pa_id, pa->pa_class, 0, devinfo, sizeof(devinfo));
169 	printf(": %s\n", devinfo);
170 	printf("%s", sc->sc_dev.dv_xname);
171 
172 	if (pci_mapreg_map(pa, IO_MAP_REG, PCI_MAPREG_TYPE_IO, 0,
173 	    &iot, &ioh, NULL, NULL)) {
174 		printf(": unable to map registers\n");
175 		return;
176 	}
177 
178 	sc->sc_glue = &pcscp_glue;
179 
180 	esc->sc_st = iot;
181 	esc->sc_sh = ioh;
182 	esc->sc_dmat = pa->pa_dmat;
183 
184 	csr = pci_conf_read(pa->pa_pc, pa->pa_tag, PCI_COMMAND_STATUS_REG);
185 	pci_conf_write(pa->pa_pc, pa->pa_tag, PCI_COMMAND_STATUS_REG,
186 	    csr | PCI_COMMAND_MASTER_ENABLE | PCI_COMMAND_IO_ENABLE);
187 
188 	/*
189 	 * XXX More of this should be in ncr53c9x_attach(), but
190 	 * XXX should we really poke around the chip that much in
191 	 * XXX the MI code?  Think about this more...
192 	 */
193 
194 	/*
195 	 * Set up static configuration info.
196 	 */
197 
198 	/*
199 	 * XXX should read configuration from EEPROM?
200 	 *
201 	 * MI ncr53c9x driver does not support configuration
202 	 * per each target device, though...
203 	 */
204 	sc->sc_id = 7;
205 	sc->sc_cfg1 = sc->sc_id | NCRCFG1_PARENB;
206 	sc->sc_cfg2 = NCRCFG2_SCSI2 | NCRCFG2_FE;
207 	sc->sc_cfg3 = NCRAMDCFG3_IDM | NCRAMDCFG3_FCLK;
208 	sc->sc_cfg4 = NCRAMDCFG4_GE12NS | NCRAMDCFG4_RADE;
209 	sc->sc_rev = NCR_VARIANT_AM53C974;
210 	sc->sc_features = NCR_F_FASTSCSI;
211 	sc->sc_cfg3_fscsi = NCRAMDCFG3_FSCSI;
212 	sc->sc_freq = 40; /* MHz */
213 
214 	/*
215 	 * XXX minsync and maxxfer _should_ be set up in MI code,
216 	 * XXX but it appears to have some dependency on what sort
217 	 * XXX of DMA we're hooked up to, etc.
218 	 */
219 
220 	/*
221 	 * This is the value used to start sync negotiations
222 	 * Note that the NCR register "SYNCTP" is programmed
223 	 * in "clocks per byte", and has a minimum value of 4.
224 	 * The SCSI period used in negotiation is one-fourth
225 	 * of the time (in nanoseconds) needed to transfer one byte.
226 	 * Since the chip's clock is given in MHz, we have the following
227 	 * formula: 4 * period = (1000 / freq) * 4
228 	 */
229 
230 	sc->sc_minsync = 1000 / sc->sc_freq;
231 
232 	/* Really no limit, but since we want to fit into the TCR... */
233 	sc->sc_maxxfer = 16 * 1024 * 1024;
234 
235 	/*
236 	 * Create the DMA maps for the data transfers.
237 	 */
238 
239 #define MDL_SEG_SIZE	0x1000 /* 4kbyte per segment */
240 #define MDL_SEG_OFFSET	0x0FFF
241 #define MDL_SIZE	(MAXPHYS / MDL_SEG_SIZE + 1) /* no hardware limit? */
242 
243 	if (bus_dmamap_create(esc->sc_dmat, MAXPHYS, MDL_SIZE, MDL_SEG_SIZE,
244 	    MDL_SEG_SIZE, BUS_DMA_NOWAIT, &esc->sc_xfermap)) {
245 		printf(": can't create DMA maps\n");
246 		return;
247 	}
248 
249 	/*
250 	 * Allocate and map memory for the MDL.
251 	 */
252 
253 	if ((error = bus_dmamem_alloc(esc->sc_dmat,
254 	    sizeof(uint32_t) * MDL_SIZE, PAGE_SIZE, 0, &seg, 1, &rseg,
255 	    BUS_DMA_NOWAIT)) != 0) {
256 		printf(": unable to allocate memory for the MDL, error = %d\n",
257 		    error);
258 		return;
259 	}
260 	if ((error = bus_dmamem_map(esc->sc_dmat, &seg, rseg,
261 	    sizeof(uint32_t) * MDL_SIZE , (caddr_t *)&esc->sc_mdladdr,
262 	    BUS_DMA_NOWAIT|BUS_DMA_COHERENT)) != 0) {
263 		printf(": unable to map the MDL memory, error = %d\n", error);
264 		return;
265 	}
266 	if ((error = bus_dmamap_create(esc->sc_dmat,
267 	    sizeof(uint32_t) * MDL_SIZE, 1, sizeof(uint32_t) * MDL_SIZE,
268 	    0, BUS_DMA_NOWAIT, &esc->sc_mdldmap)) != 0) {
269 		printf(": unable to map_create for the MDL, error = %d\n",
270 		    error);
271 		return;
272 	}
273 	if ((error = bus_dmamap_load(esc->sc_dmat, esc->sc_mdldmap,
274 	     esc->sc_mdladdr, sizeof(uint32_t) * MDL_SIZE,
275 	     NULL, BUS_DMA_NOWAIT)) != 0) {
276 		printf(": unable to load for the MDL, error = %d\n", error);
277 		return;
278 	}
279 
280 	/* map and establish interrupt */
281 	if (pci_intr_map(pa, &ih)) {
282 		printf(": couldn't map interrupt\n");
283 		return;
284 	}
285 
286 	intrstr = pci_intr_string(pa->pa_pc, ih);
287 	esc->sc_ih = pci_intr_establish(pa->pa_pc, ih, IPL_BIO,
288 	    ncr53c9x_intr, esc);
289 	if (esc->sc_ih == NULL) {
290 		printf(": couldn't establish interrupt");
291 		if (intrstr != NULL)
292 			printf(" at %s", intrstr);
293 		printf("\n");
294 		return;
295 	}
296 	if (intrstr != NULL)
297 		printf(": interrupting at %s\n", intrstr);
298 
299 	/* Do the common parts of attachment. */
300 	printf("%s", sc->sc_dev.dv_xname);
301 	sc->sc_adapter.adapt_minphys = minphys;
302 	sc->sc_adapter.adapt_request = ncr53c9x_scsipi_request;
303 	ncr53c9x_attach(sc);
304 
305 	/* Turn on target selection using the `DMA' method */
306 	sc->sc_features |= NCR_F_DMASELECT;
307 }
308 
309 CFATTACH_DECL(pcscp, sizeof(struct pcscp_softc),
310     pcscp_match, pcscp_attach, NULL, NULL);
311 
312 /*
313  * Glue functions.
314  */
315 
316 static u_char
317 pcscp_read_reg(struct ncr53c9x_softc *sc, int reg)
318 {
319 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
320 
321 	return PCSCP_READ_REG(esc, reg);
322 }
323 
324 static void
325 pcscp_write_reg(struct ncr53c9x_softc *sc, int reg, u_char v)
326 {
327 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
328 
329 	PCSCP_WRITE_REG(esc, reg, v);
330 }
331 
332 static int
333 pcscp_dma_isintr(struct ncr53c9x_softc *sc)
334 {
335 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
336 
337 	return (PCSCP_READ_REG(esc, NCR_STAT) & NCRSTAT_INT) != 0;
338 }
339 
340 static void
341 pcscp_dma_reset(struct ncr53c9x_softc *sc)
342 {
343 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
344 
345 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_IDLE);
346 
347 	esc->sc_active = 0;
348 }
349 
350 static int
351 pcscp_dma_intr(struct ncr53c9x_softc *sc)
352 {
353 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
354 	int trans, resid, i;
355 	bus_dmamap_t dmap = esc->sc_xfermap;
356 	int datain = esc->sc_datain;
357 	uint32_t dmastat;
358 	char *p = NULL;
359 
360 	dmastat = READ_DMAREG(esc, DMA_STAT);
361 
362 	if (dmastat & DMASTAT_ERR) {
363 		/* XXX not tested... */
364 		WRITE_DMAREG(esc, DMA_CMD,
365 		    DMACMD_ABORT | (datain ? DMACMD_DIR : 0));
366 
367 		printf("%s: error: DMA error detected; Aborting.\n",
368 		    sc->sc_dev.dv_xname);
369 		bus_dmamap_unload(esc->sc_dmat, dmap);
370 		return -1;
371 	}
372 
373 	if (dmastat & DMASTAT_ABT) {
374 		/* XXX What should be done? */
375 		printf("%s: dma_intr: DMA aborted.\n", sc->sc_dev.dv_xname);
376 		WRITE_DMAREG(esc, DMA_CMD,
377 		    DMACMD_IDLE | (datain ? DMACMD_DIR : 0));
378 		esc->sc_active = 0;
379 		return 0;
380 	}
381 
382 #ifdef DIAGNOSTIC
383 	/* This is an "assertion" :) */
384 	if (esc->sc_active == 0)
385 		panic("pcscp dmaintr: DMA wasn't active");
386 #endif
387 
388 	/* DMA has stopped */
389 
390 	esc->sc_active = 0;
391 
392 	if (esc->sc_dmasize == 0) {
393 		/* A "Transfer Pad" operation completed */
394 		NCR_DMA(("dmaintr: discarded %d bytes (tcl=%d, tcm=%d)\n",
395 		    PCSCP_READ_REG(esc, NCR_TCL) |
396 		    (PCSCP_READ_REG(esc, NCR_TCM) << 8),
397 		    PCSCP_READ_REG(esc, NCR_TCL),
398 		    PCSCP_READ_REG(esc, NCR_TCM)));
399 		return 0;
400 	}
401 
402 	resid = 0;
403 	/*
404 	 * If a transfer onto the SCSI bus gets interrupted by the device
405 	 * (e.g. for a SAVEPOINTER message), the data in the FIFO counts
406 	 * as residual since the ESP counter registers get decremented as
407 	 * bytes are clocked into the FIFO.
408 	 */
409 	if (!datain &&
410 	    (resid = (PCSCP_READ_REG(esc, NCR_FFLAG) & NCRFIFO_FF)) != 0) {
411 		NCR_DMA(("pcscp_dma_intr: empty esp FIFO of %d ", resid));
412 	}
413 
414 	if ((sc->sc_espstat & NCRSTAT_TC) == 0) {
415 		/*
416 		 * `Terminal count' is off, so read the residue
417 		 * out of the ESP counter registers.
418 		 */
419 		if (datain) {
420 			resid = PCSCP_READ_REG(esc, NCR_FFLAG) & NCRFIFO_FF;
421 			while (resid > 1)
422 				resid =
423 				    PCSCP_READ_REG(esc, NCR_FFLAG) & NCRFIFO_FF;
424 			WRITE_DMAREG(esc, DMA_CMD, DMACMD_BLAST | DMACMD_MDL |
425 			    (datain ? DMACMD_DIR : 0));
426 
427 			for (i = 0; i < 0x8000; i++) /* XXX 0x8000 ? */
428 				if (READ_DMAREG(esc, DMA_STAT) & DMASTAT_BCMP)
429 					break;
430 
431 			/* See the below comments... */
432 			if (resid)
433 				p = *esc->sc_dmaaddr;
434 		}
435 
436 		resid += PCSCP_READ_REG(esc, NCR_TCL) |
437 		    (PCSCP_READ_REG(esc, NCR_TCM) << 8) |
438 		    (PCSCP_READ_REG(esc, NCR_TCH) << 16);
439 	} else {
440 		while ((dmastat & DMASTAT_DONE) == 0)
441 			dmastat = READ_DMAREG(esc, DMA_STAT);
442 	}
443 
444 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_IDLE | (datain ? DMACMD_DIR : 0));
445 
446 	/* sync MDL */
447 	bus_dmamap_sync(esc->sc_dmat, esc->sc_mdldmap,
448 	    0, sizeof(uint32_t) * dmap->dm_nsegs, BUS_DMASYNC_POSTWRITE);
449 	/* sync transfer buffer */
450 	bus_dmamap_sync(esc->sc_dmat, dmap, 0, dmap->dm_mapsize,
451 	    datain ? BUS_DMASYNC_POSTREAD : BUS_DMASYNC_POSTWRITE);
452 	bus_dmamap_unload(esc->sc_dmat, dmap);
453 
454 	trans = esc->sc_dmasize - resid;
455 
456 	/*
457 	 * From the technical manual notes:
458 	 *
459 	 * `In some odd byte conditions, one residual byte will be left
460 	 *  in the SCSI FIFO, and the FIFO flags will never count to 0.
461 	 *  When this happens, the residual byte should be retrieved
462 	 *  via PIO following completion of the BLAST operation.'
463 	 */
464 
465 	if (p) {
466 		p += trans;
467 		*p = PCSCP_READ_REG(esc, NCR_FIFO);
468 		trans++;
469 	}
470 
471 	if (trans < 0) {			/* transferred < 0 ? */
472 #if 0
473 		/*
474 		 * This situation can happen in perfectly normal operation
475 		 * if the ESP is reselected while using DMA to select
476 		 * another target.  As such, don't print the warning.
477 		 */
478 		printf("%s: xfer (%d) > req (%d)\n",
479 		    sc->sc_dev.dv_xname, trans, esc->sc_dmasize);
480 #endif
481 		trans = esc->sc_dmasize;
482 	}
483 
484 	NCR_DMA(("dmaintr: tcl=%d, tcm=%d, tch=%d; trans=%d, resid=%d\n",
485 	    PCSCP_READ_REG(esc, NCR_TCL),
486 	    PCSCP_READ_REG(esc, NCR_TCM),
487 	    PCSCP_READ_REG(esc, NCR_TCH),
488 	    trans, resid));
489 
490 	*esc->sc_dmalen -= trans;
491 	*esc->sc_dmaaddr += trans;
492 
493 	return 0;
494 }
495 
496 static int
497 pcscp_dma_setup(struct ncr53c9x_softc *sc, caddr_t *addr, size_t *len,
498     int datain, size_t *dmasize)
499 {
500 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
501 	bus_dmamap_t dmap = esc->sc_xfermap;
502 	uint32_t *mdl;
503 	int error, nseg, seg;
504 	bus_addr_t s_offset, s_addr;
505 
506 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_IDLE | (datain ? DMACMD_DIR : 0));
507 
508 	esc->sc_dmaaddr = addr;
509 	esc->sc_dmalen = len;
510 	esc->sc_dmasize = *dmasize;
511 	esc->sc_datain = datain;
512 
513 #ifdef DIAGNOSTIC
514 	if ((*dmasize / MDL_SEG_SIZE) > MDL_SIZE)
515 		panic("pcscp: transfer size too large");
516 #endif
517 
518 	/*
519 	 * No need to set up DMA in `Transfer Pad' operation.
520 	 * (case of *dmasize == 0)
521 	 */
522 	if (*dmasize == 0)
523 		return 0;
524 
525 	error = bus_dmamap_load(esc->sc_dmat, dmap, *esc->sc_dmaaddr,
526 	    *esc->sc_dmalen, NULL,
527 	    ((sc->sc_nexus->xs->xs_control & XS_CTL_NOSLEEP) ?
528 	    BUS_DMA_NOWAIT : BUS_DMA_WAITOK) | BUS_DMA_STREAMING |
529 	    ((sc->sc_nexus->xs->xs_control & XS_CTL_DATA_IN) ?
530 	     BUS_DMA_READ : BUS_DMA_WRITE));
531 	if (error) {
532 		printf("%s: unable to load dmamap, error = %d\n",
533 		    sc->sc_dev.dv_xname, error);
534 		return error;
535 	}
536 
537 	/* set transfer length */
538 	WRITE_DMAREG(esc, DMA_STC, *dmasize);
539 
540 	/* set up MDL */
541 	mdl = esc->sc_mdladdr;
542 	nseg = dmap->dm_nsegs;
543 
544 	/* the first segment is possibly not aligned with 4k MDL boundary */
545 	s_addr = dmap->dm_segs[0].ds_addr;
546 	s_offset = s_addr & MDL_SEG_OFFSET;
547 	s_addr -= s_offset;
548 
549 	/* set the first MDL and offset */
550 	WRITE_DMAREG(esc, DMA_SPA, s_offset);
551 	*mdl++ = htole32(s_addr);
552 
553 	/* the rest dmamap segments are aligned with 4k boundary */
554 	for (seg = 1; seg < nseg; seg++)
555 		*mdl++ = htole32(dmap->dm_segs[seg].ds_addr);
556 
557 	return 0;
558 }
559 
560 static void
561 pcscp_dma_go(struct ncr53c9x_softc *sc)
562 {
563 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
564 	bus_dmamap_t dmap = esc->sc_xfermap, mdldmap = esc->sc_mdldmap;
565 	int datain = esc->sc_datain;
566 
567 	/* No DMA transfer in Transfer Pad operation */
568 	if (esc->sc_dmasize == 0)
569 		return;
570 
571 	/* sync transfer buffer */
572 	bus_dmamap_sync(esc->sc_dmat, dmap, 0, dmap->dm_mapsize,
573 	    datain ? BUS_DMASYNC_PREREAD : BUS_DMASYNC_PREWRITE);
574 
575 	/* sync MDL */
576 	bus_dmamap_sync(esc->sc_dmat, mdldmap,
577 	    0, sizeof(uint32_t) * dmap->dm_nsegs, BUS_DMASYNC_PREWRITE);
578 
579 	/* set Starting MDL Address */
580 	WRITE_DMAREG(esc, DMA_SMDLA, mdldmap->dm_segs[0].ds_addr);
581 
582 	/* set DMA command register bits */
583 	/* XXX DMA Transfer Interrupt Enable bit is broken? */
584 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_IDLE | DMACMD_MDL |
585 	    /* DMACMD_INTE | */
586 	    (datain ? DMACMD_DIR : 0));
587 
588 	/* issue DMA start command */
589 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_START | DMACMD_MDL |
590 	    /* DMACMD_INTE | */
591 	    (datain ? DMACMD_DIR : 0));
592 
593 	esc->sc_active = 1;
594 }
595 
596 static void
597 pcscp_dma_stop(struct ncr53c9x_softc *sc)
598 {
599 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
600 
601 	/* DMA stop */
602 	/* XXX What should we do here ? */
603 	WRITE_DMAREG(esc, DMA_CMD,
604 	    DMACMD_ABORT | (esc->sc_datain ? DMACMD_DIR : 0));
605 	bus_dmamap_unload(esc->sc_dmat, esc->sc_xfermap);
606 
607 	esc->sc_active = 0;
608 }
609 
610 static int
611 pcscp_dma_isactive(struct ncr53c9x_softc *sc)
612 {
613 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
614 
615 	/* XXX should check esc->sc_active? */
616 	if ((READ_DMAREG(esc, DMA_CMD) & DMACMD_CMD) != DMACMD_IDLE)
617 		return 1;
618 	return 0;
619 }
620