xref: /netbsd-src/sys/dev/pci/pcscp.c (revision 6a493d6bc668897c91594964a732d38505b70cbb)
1 /*	$NetBSD: pcscp.c,v 1.46 2012/01/30 19:41:22 drochner 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  *
20  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
22  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
23  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
24  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30  * POSSIBILITY OF SUCH DAMAGE.
31  */
32 
33 /*
34  * pcscp.c: device dependent code for AMD Am53c974 (PCscsi-PCI)
35  * written by Izumi Tsutsui <tsutsui@NetBSD.org>
36  *
37  * Technical manual available at
38  * http://www.amd.com/files/connectivitysolutions/networking/archivednetworking/19113.pdf
39  */
40 
41 #include <sys/cdefs.h>
42 __KERNEL_RCSID(0, "$NetBSD: pcscp.c,v 1.46 2012/01/30 19:41:22 drochner Exp $");
43 
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/device.h>
47 #include <sys/buf.h>
48 
49 #include <sys/bus.h>
50 #include <sys/intr.h>
51 
52 #include <dev/scsipi/scsipi_all.h>
53 #include <dev/scsipi/scsi_all.h>
54 #include <dev/scsipi/scsiconf.h>
55 
56 #include <dev/pci/pcireg.h>
57 #include <dev/pci/pcivar.h>
58 #include <dev/pci/pcidevs.h>
59 
60 #include <dev/ic/ncr53c9xreg.h>
61 #include <dev/ic/ncr53c9xvar.h>
62 
63 #include <dev/pci/pcscpreg.h>
64 
65 #define IO_MAP_REG	0x10
66 
67 struct pcscp_softc {
68 	struct ncr53c9x_softc sc_ncr53c9x;	/* glue to MI code */
69 
70 	bus_space_tag_t sc_st;		/* bus space tag */
71 	bus_space_handle_t sc_sh;	/* bus space handle */
72 	void *sc_ih;			/* interrupt cookie */
73 
74 	bus_dma_tag_t sc_dmat;		/* DMA tag */
75 
76 	bus_dmamap_t sc_xfermap;	/* DMA map for transfers */
77 
78 	uint32_t *sc_mdladdr;		/* MDL array */
79 	bus_dmamap_t sc_mdldmap;	/* MDL DMA map */
80 
81 	int	sc_active;		/* DMA state */
82 	int	sc_datain;		/* DMA Data Direction */
83 	size_t	sc_dmasize;		/* DMA size */
84 	uint8_t	**sc_dmaaddr;		/* DMA address */
85 	size_t	*sc_dmalen;		/* DMA length */
86 };
87 
88 #define	READ_DMAREG(sc, reg) \
89 	bus_space_read_4((sc)->sc_st, (sc)->sc_sh, (reg))
90 #define	WRITE_DMAREG(sc, reg, var) \
91 	bus_space_write_4((sc)->sc_st, (sc)->sc_sh, (reg), (var))
92 
93 #define	PCSCP_READ_REG(sc, reg)	\
94 	bus_space_read_1((sc)->sc_st, (sc)->sc_sh, (reg) << 2)
95 #define	PCSCP_WRITE_REG(sc, reg, val)	\
96 	bus_space_write_1((sc)->sc_st, (sc)->sc_sh, (reg) << 2, (val))
97 
98 
99 static int pcscp_match(device_t, cfdata_t, void *);
100 static void pcscp_attach(device_t, device_t, void *);
101 
102 CFATTACH_DECL_NEW(pcscp, sizeof(struct pcscp_softc),
103     pcscp_match, pcscp_attach, NULL, NULL);
104 
105 /*
106  * Functions and the switch for the MI code.
107  */
108 
109 static uint8_t	pcscp_read_reg(struct ncr53c9x_softc *, int);
110 static void	pcscp_write_reg(struct ncr53c9x_softc *, int, uint8_t);
111 static int	pcscp_dma_isintr(struct ncr53c9x_softc *);
112 static void	pcscp_dma_reset(struct ncr53c9x_softc *);
113 static int	pcscp_dma_intr(struct ncr53c9x_softc *);
114 static int	pcscp_dma_setup(struct ncr53c9x_softc *, uint8_t **, size_t *,
115 		    int, size_t *);
116 static void	pcscp_dma_go(struct ncr53c9x_softc *);
117 static void	pcscp_dma_stop(struct ncr53c9x_softc *);
118 static int	pcscp_dma_isactive(struct ncr53c9x_softc *);
119 
120 static struct ncr53c9x_glue pcscp_glue = {
121 	pcscp_read_reg,
122 	pcscp_write_reg,
123 	pcscp_dma_isintr,
124 	pcscp_dma_reset,
125 	pcscp_dma_intr,
126 	pcscp_dma_setup,
127 	pcscp_dma_go,
128 	pcscp_dma_stop,
129 	pcscp_dma_isactive,
130 	NULL,			/* gl_clear_latched_intr */
131 };
132 
133 static int
134 pcscp_match(device_t parent, cfdata_t cf, void *aux)
135 {
136 	struct pci_attach_args *pa = aux;
137 
138 	if (PCI_VENDOR(pa->pa_id) != PCI_VENDOR_AMD)
139 		return 0;
140 
141 	switch (PCI_PRODUCT(pa->pa_id)) {
142 	case PCI_PRODUCT_AMD_PCSCSI_PCI:
143 		return 1;
144 	}
145 	return 0;
146 }
147 
148 /*
149  * Attach this instance, and then all the sub-devices
150  */
151 static void
152 pcscp_attach(device_t parent, device_t self, void *aux)
153 {
154 	struct pcscp_softc *esc = device_private(self);
155 	struct ncr53c9x_softc *sc = &esc->sc_ncr53c9x;
156 	struct pci_attach_args *pa = aux;
157 	bus_space_tag_t iot;
158 	bus_space_handle_t ioh;
159 	pci_intr_handle_t ih;
160 	const char *intrstr;
161 	pcireg_t csr;
162 	bus_dma_segment_t seg;
163 	int error, rseg;
164 
165 	sc->sc_dev = self;
166 	pci_aprint_devinfo(pa, NULL);
167 	aprint_normal("%s", device_xname(sc->sc_dev));
168 
169 	if (pci_mapreg_map(pa, IO_MAP_REG, PCI_MAPREG_TYPE_IO, 0,
170 	    &iot, &ioh, NULL, NULL)) {
171 		aprint_error(": unable to map registers\n");
172 		return;
173 	}
174 
175 	sc->sc_glue = &pcscp_glue;
176 
177 	esc->sc_st = iot;
178 	esc->sc_sh = ioh;
179 	esc->sc_dmat = pa->pa_dmat;
180 
181 	csr = pci_conf_read(pa->pa_pc, pa->pa_tag, PCI_COMMAND_STATUS_REG);
182 	pci_conf_write(pa->pa_pc, pa->pa_tag, PCI_COMMAND_STATUS_REG,
183 	    csr | PCI_COMMAND_MASTER_ENABLE | PCI_COMMAND_IO_ENABLE);
184 
185 	/*
186 	 * XXX More of this should be in ncr53c9x_attach(), but
187 	 * XXX should we really poke around the chip that much in
188 	 * XXX the MI code?  Think about this more...
189 	 */
190 
191 	/*
192 	 * Set up static configuration info.
193 	 */
194 
195 	/*
196 	 * XXX should read configuration from EEPROM?
197 	 *
198 	 * MI ncr53c9x driver does not support configuration
199 	 * per each target device, though...
200 	 */
201 	sc->sc_id = 7;
202 	sc->sc_cfg1 = sc->sc_id | NCRCFG1_PARENB;
203 	sc->sc_cfg2 = NCRCFG2_SCSI2 | NCRCFG2_FE;
204 	sc->sc_cfg3 = NCRAMDCFG3_IDM | NCRAMDCFG3_FCLK;
205 	sc->sc_cfg4 = NCRAMDCFG4_GE12NS | NCRAMDCFG4_RADE;
206 	sc->sc_rev = NCR_VARIANT_AM53C974;
207 	sc->sc_features = NCR_F_FASTSCSI;
208 	sc->sc_cfg3_fscsi = NCRAMDCFG3_FSCSI;
209 	sc->sc_freq = 40; /* MHz */
210 
211 	/*
212 	 * XXX minsync and maxxfer _should_ be set up in MI code,
213 	 * XXX but it appears to have some dependency on what sort
214 	 * XXX of DMA we're hooked up to, etc.
215 	 */
216 
217 	/*
218 	 * This is the value used to start sync negotiations
219 	 * Note that the NCR register "SYNCTP" is programmed
220 	 * in "clocks per byte", and has a minimum value of 4.
221 	 * The SCSI period used in negotiation is one-fourth
222 	 * of the time (in nanoseconds) needed to transfer one byte.
223 	 * Since the chip's clock is given in MHz, we have the following
224 	 * formula: 4 * period = (1000 / freq) * 4
225 	 */
226 
227 	sc->sc_minsync = 1000 / sc->sc_freq;
228 
229 	/* Really no limit, but since we want to fit into the TCR... */
230 	sc->sc_maxxfer = 16 * 1024 * 1024;
231 
232 	/*
233 	 * Create the DMA maps for the data transfers.
234 	 */
235 
236 #define MDL_SEG_SIZE	0x1000 /* 4kbyte per segment */
237 #define MDL_SEG_OFFSET	0x0FFF
238 #define MDL_SIZE	(MAXPHYS / MDL_SEG_SIZE + 1) /* no hardware limit? */
239 
240 	if (bus_dmamap_create(esc->sc_dmat, MAXPHYS, MDL_SIZE, MDL_SEG_SIZE,
241 	    MDL_SEG_SIZE, BUS_DMA_NOWAIT, &esc->sc_xfermap)) {
242 		aprint_error(": can't create DMA maps\n");
243 		return;
244 	}
245 
246 	/*
247 	 * Allocate and map memory for the MDL.
248 	 */
249 
250 	if ((error = bus_dmamem_alloc(esc->sc_dmat,
251 	    sizeof(uint32_t) * MDL_SIZE, PAGE_SIZE, 0, &seg, 1, &rseg,
252 	    BUS_DMA_NOWAIT)) != 0) {
253 		aprint_error(": unable to allocate memory for the MDL,"
254 		    " error = %d\n", error);
255 		goto fail_0;
256 	}
257 	if ((error = bus_dmamem_map(esc->sc_dmat, &seg, rseg,
258 	    sizeof(uint32_t) * MDL_SIZE , (void **)&esc->sc_mdladdr,
259 	    BUS_DMA_NOWAIT|BUS_DMA_COHERENT)) != 0) {
260 		aprint_error(": unable to map the MDL memory, error = %d\n",
261 		    error);
262 		goto fail_1;
263 	}
264 	if ((error = bus_dmamap_create(esc->sc_dmat,
265 	    sizeof(uint32_t) * MDL_SIZE, 1, sizeof(uint32_t) * MDL_SIZE,
266 	    0, BUS_DMA_NOWAIT, &esc->sc_mdldmap)) != 0) {
267 		aprint_error(": unable to map_create for the MDL, error = %d\n",
268 		    error);
269 		goto fail_2;
270 	}
271 	if ((error = bus_dmamap_load(esc->sc_dmat, esc->sc_mdldmap,
272 	     esc->sc_mdladdr, sizeof(uint32_t) * MDL_SIZE,
273 	     NULL, BUS_DMA_NOWAIT)) != 0) {
274 		aprint_error(": unable to load for the MDL, error = %d\n",
275 		    error);
276 		goto fail_3;
277 	}
278 
279 	/* map and establish interrupt */
280 	if (pci_intr_map(pa, &ih)) {
281 		aprint_error(": couldn't map interrupt\n");
282 		goto fail_4;
283 	}
284 
285 	intrstr = pci_intr_string(pa->pa_pc, ih);
286 	esc->sc_ih = pci_intr_establish(pa->pa_pc, ih, IPL_BIO,
287 	    ncr53c9x_intr, esc);
288 	if (esc->sc_ih == NULL) {
289 		aprint_error(": couldn't establish interrupt");
290 		if (intrstr != NULL)
291 			aprint_error(" at %s", intrstr);
292 		aprint_error("\n");
293 		goto fail_4;
294 	}
295 	if (intrstr != NULL) {
296 		aprint_normal(": interrupting at %s\n", intrstr);
297 		aprint_normal("%s", device_xname(sc->sc_dev));
298 	}
299 
300 	/* Do the common parts of attachment. */
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 	return;
309 
310  fail_4:
311 	bus_dmamap_unload(esc->sc_dmat, esc->sc_mdldmap);
312  fail_3:
313 	bus_dmamap_destroy(esc->sc_dmat, esc->sc_mdldmap);
314  fail_2:
315 	bus_dmamem_unmap(esc->sc_dmat, (void *)esc->sc_mdldmap,
316 	    sizeof(uint32_t) * MDL_SIZE);
317  fail_1:
318 	bus_dmamem_free(esc->sc_dmat, &seg, rseg);
319  fail_0:
320 	bus_dmamap_destroy(esc->sc_dmat, esc->sc_xfermap);
321 }
322 
323 /*
324  * Glue functions.
325  */
326 
327 static uint8_t
328 pcscp_read_reg(struct ncr53c9x_softc *sc, int reg)
329 {
330 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
331 
332 	return PCSCP_READ_REG(esc, reg);
333 }
334 
335 static void
336 pcscp_write_reg(struct ncr53c9x_softc *sc, int reg, uint8_t v)
337 {
338 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
339 
340 	PCSCP_WRITE_REG(esc, reg, v);
341 }
342 
343 static int
344 pcscp_dma_isintr(struct ncr53c9x_softc *sc)
345 {
346 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
347 
348 	return (PCSCP_READ_REG(esc, NCR_STAT) & NCRSTAT_INT) != 0;
349 }
350 
351 static void
352 pcscp_dma_reset(struct ncr53c9x_softc *sc)
353 {
354 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
355 
356 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_IDLE);
357 
358 	esc->sc_active = 0;
359 }
360 
361 static int
362 pcscp_dma_intr(struct ncr53c9x_softc *sc)
363 {
364 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
365 	int trans, resid, i;
366 	bus_dmamap_t dmap = esc->sc_xfermap;
367 	int datain = esc->sc_datain;
368 	uint32_t dmastat;
369 	uint8_t *p = NULL;
370 
371 	dmastat = READ_DMAREG(esc, DMA_STAT);
372 
373 	if (dmastat & DMASTAT_ERR) {
374 		/* XXX not tested... */
375 		WRITE_DMAREG(esc, DMA_CMD,
376 		    DMACMD_ABORT | (datain ? DMACMD_DIR : 0));
377 
378 		printf("%s: error: DMA error detected; Aborting.\n",
379 		    device_xname(sc->sc_dev));
380 		bus_dmamap_unload(esc->sc_dmat, dmap);
381 		return -1;
382 	}
383 
384 	if (dmastat & DMASTAT_ABT) {
385 		/* XXX What should be done? */
386 		printf("%s: %s: DMA aborted.\n",
387 		    device_xname(sc->sc_dev), __func__);
388 		WRITE_DMAREG(esc, DMA_CMD,
389 		    DMACMD_IDLE | (datain ? DMACMD_DIR : 0));
390 		esc->sc_active = 0;
391 		return 0;
392 	}
393 
394 #ifdef DIAGNOSTIC
395 	/* This is an "assertion" :) */
396 	if (esc->sc_active == 0)
397 		panic("%s: %s: DMA wasn't active",
398 		    device_xname(sc->sc_dev), __func__);
399 #endif
400 
401 	/* DMA has stopped */
402 
403 	esc->sc_active = 0;
404 
405 	if (esc->sc_dmasize == 0) {
406 		/* A "Transfer Pad" operation completed */
407 		NCR_DMA(("%s: discarded %d bytes (tcl=%d, tcm=%d)\n",
408 		    __func__,
409 		    PCSCP_READ_REG(esc, NCR_TCL) |
410 		    (PCSCP_READ_REG(esc, NCR_TCM) << 8),
411 		    PCSCP_READ_REG(esc, NCR_TCL),
412 		    PCSCP_READ_REG(esc, NCR_TCM)));
413 		return 0;
414 	}
415 
416 	resid = 0;
417 	/*
418 	 * If a transfer onto the SCSI bus gets interrupted by the device
419 	 * (e.g. for a SAVEPOINTER message), the data in the FIFO counts
420 	 * as residual since the ESP counter registers get decremented as
421 	 * bytes are clocked into the FIFO.
422 	 */
423 	if (!datain &&
424 	    (resid = (PCSCP_READ_REG(esc, NCR_FFLAG) & NCRFIFO_FF)) != 0) {
425 		NCR_DMA(("%s: empty esp FIFO of %d ", __func__, resid));
426 	}
427 
428 	if ((sc->sc_espstat & NCRSTAT_TC) == 0) {
429 		/*
430 		 * `Terminal count' is off, so read the residue
431 		 * out of the ESP counter registers.
432 		 */
433 		if (datain) {
434 			resid = PCSCP_READ_REG(esc, NCR_FFLAG) & NCRFIFO_FF;
435 			while (resid > 1)
436 				resid =
437 				    PCSCP_READ_REG(esc, NCR_FFLAG) & NCRFIFO_FF;
438 			WRITE_DMAREG(esc, DMA_CMD, DMACMD_BLAST | DMACMD_MDL |
439 			    (datain ? DMACMD_DIR : 0));
440 
441 			for (i = 0; i < 1000; i++) { /* XXX */
442 				if (READ_DMAREG(esc, DMA_STAT) & DMASTAT_BCMP)
443 					break;
444 				DELAY(1);
445 			}
446 
447 			/* See the below comments... */
448 			if (resid)
449 				p = *esc->sc_dmaaddr;
450 		}
451 
452 		resid += PCSCP_READ_REG(esc, NCR_TCL) |
453 		    (PCSCP_READ_REG(esc, NCR_TCM) << 8) |
454 		    (PCSCP_READ_REG(esc, NCR_TCH) << 16);
455 	} else {
456 		while ((dmastat & DMASTAT_DONE) == 0)
457 			dmastat = READ_DMAREG(esc, DMA_STAT);
458 	}
459 
460 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_IDLE | (datain ? DMACMD_DIR : 0));
461 
462 	/* sync MDL */
463 	bus_dmamap_sync(esc->sc_dmat, esc->sc_mdldmap,
464 	    0, sizeof(uint32_t) * dmap->dm_nsegs, BUS_DMASYNC_POSTWRITE);
465 	/* sync transfer buffer */
466 	bus_dmamap_sync(esc->sc_dmat, dmap, 0, dmap->dm_mapsize,
467 	    datain ? BUS_DMASYNC_POSTREAD : BUS_DMASYNC_POSTWRITE);
468 	bus_dmamap_unload(esc->sc_dmat, dmap);
469 
470 	trans = esc->sc_dmasize - resid;
471 
472 	/*
473 	 * From the technical manual notes:
474 	 *
475 	 * `In some odd byte conditions, one residual byte will be left
476 	 *  in the SCSI FIFO, and the FIFO flags will never count to 0.
477 	 *  When this happens, the residual byte should be retrieved
478 	 *  via PIO following completion of the BLAST operation.'
479 	 */
480 
481 	if (p) {
482 		p += trans;
483 		*p = PCSCP_READ_REG(esc, NCR_FIFO);
484 		trans++;
485 	}
486 
487 	if (trans < 0) {			/* transferred < 0 ? */
488 #if 0
489 		/*
490 		 * This situation can happen in perfectly normal operation
491 		 * if the ESP is reselected while using DMA to select
492 		 * another target.  As such, don't print the warning.
493 		 */
494 		printf("%s: xfer (%d) > req (%d)\n",
495 		    device_xname(sc->sc_dev), trans, esc->sc_dmasize);
496 #endif
497 		trans = esc->sc_dmasize;
498 	}
499 
500 	NCR_DMA(("%s: tcl=%d, tcm=%d, tch=%d; trans=%d, resid=%d\n",
501 	    __func__,
502 	    PCSCP_READ_REG(esc, NCR_TCL),
503 	    PCSCP_READ_REG(esc, NCR_TCM),
504 	    PCSCP_READ_REG(esc, NCR_TCH),
505 	    trans, resid));
506 
507 	*esc->sc_dmalen -= trans;
508 	*esc->sc_dmaaddr += trans;
509 
510 	return 0;
511 }
512 
513 static int
514 pcscp_dma_setup(struct ncr53c9x_softc *sc, uint8_t **addr, size_t *len,
515     int datain, size_t *dmasize)
516 {
517 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
518 	bus_dmamap_t dmap = esc->sc_xfermap;
519 	uint32_t *mdl;
520 	int error, nseg, seg;
521 	bus_addr_t s_offset, s_addr;
522 
523 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_IDLE | (datain ? DMACMD_DIR : 0));
524 
525 	esc->sc_dmaaddr = addr;
526 	esc->sc_dmalen = len;
527 	esc->sc_dmasize = *dmasize;
528 	esc->sc_datain = datain;
529 
530 #ifdef DIAGNOSTIC
531 	if ((*dmasize / MDL_SEG_SIZE) > MDL_SIZE)
532 		panic("%s: transfer size too large", device_xname(sc->sc_dev));
533 #endif
534 
535 	/*
536 	 * No need to set up DMA in `Transfer Pad' operation.
537 	 * (case of *dmasize == 0)
538 	 */
539 	if (*dmasize == 0)
540 		return 0;
541 
542 	error = bus_dmamap_load(esc->sc_dmat, dmap, *esc->sc_dmaaddr,
543 	    *esc->sc_dmalen, NULL,
544 	    ((sc->sc_nexus->xs->xs_control & XS_CTL_NOSLEEP) ?
545 	    BUS_DMA_NOWAIT : BUS_DMA_WAITOK) | BUS_DMA_STREAMING |
546 	    ((sc->sc_nexus->xs->xs_control & XS_CTL_DATA_IN) ?
547 	     BUS_DMA_READ : BUS_DMA_WRITE));
548 	if (error) {
549 		printf("%s: unable to load dmamap, error = %d\n",
550 		    device_xname(sc->sc_dev), error);
551 		return error;
552 	}
553 
554 	/* set transfer length */
555 	WRITE_DMAREG(esc, DMA_STC, *dmasize);
556 
557 	/* set up MDL */
558 	mdl = esc->sc_mdladdr;
559 	nseg = dmap->dm_nsegs;
560 
561 	/* the first segment is possibly not aligned with 4k MDL boundary */
562 	s_addr = dmap->dm_segs[0].ds_addr;
563 	s_offset = s_addr & MDL_SEG_OFFSET;
564 	s_addr -= s_offset;
565 
566 	/* set the first MDL and offset */
567 	WRITE_DMAREG(esc, DMA_SPA, s_offset);
568 	*mdl++ = htole32(s_addr);
569 
570 	/* the rest dmamap segments are aligned with 4k boundary */
571 	for (seg = 1; seg < nseg; seg++)
572 		*mdl++ = htole32(dmap->dm_segs[seg].ds_addr);
573 
574 	return 0;
575 }
576 
577 static void
578 pcscp_dma_go(struct ncr53c9x_softc *sc)
579 {
580 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
581 	bus_dmamap_t dmap = esc->sc_xfermap, mdldmap = esc->sc_mdldmap;
582 	int datain = esc->sc_datain;
583 
584 	/* No DMA transfer in Transfer Pad operation */
585 	if (esc->sc_dmasize == 0)
586 		return;
587 
588 	/* sync transfer buffer */
589 	bus_dmamap_sync(esc->sc_dmat, dmap, 0, dmap->dm_mapsize,
590 	    datain ? BUS_DMASYNC_PREREAD : BUS_DMASYNC_PREWRITE);
591 
592 	/* sync MDL */
593 	bus_dmamap_sync(esc->sc_dmat, mdldmap,
594 	    0, sizeof(uint32_t) * dmap->dm_nsegs, BUS_DMASYNC_PREWRITE);
595 
596 	/* set Starting MDL Address */
597 	WRITE_DMAREG(esc, DMA_SMDLA, mdldmap->dm_segs[0].ds_addr);
598 
599 	/* set DMA command register bits */
600 	/* XXX DMA Transfer Interrupt Enable bit is broken? */
601 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_IDLE | DMACMD_MDL |
602 	    /* DMACMD_INTE | */
603 	    (datain ? DMACMD_DIR : 0));
604 
605 	/* issue DMA start command */
606 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_START | DMACMD_MDL |
607 	    /* DMACMD_INTE | */
608 	    (datain ? DMACMD_DIR : 0));
609 
610 	esc->sc_active = 1;
611 }
612 
613 static void
614 pcscp_dma_stop(struct ncr53c9x_softc *sc)
615 {
616 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
617 
618 	/* DMA stop */
619 	/* XXX What should we do here ? */
620 	WRITE_DMAREG(esc, DMA_CMD,
621 	    DMACMD_ABORT | (esc->sc_datain ? DMACMD_DIR : 0));
622 	bus_dmamap_unload(esc->sc_dmat, esc->sc_xfermap);
623 
624 	esc->sc_active = 0;
625 }
626 
627 static int
628 pcscp_dma_isactive(struct ncr53c9x_softc *sc)
629 {
630 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
631 
632 	/* XXX should check esc->sc_active? */
633 	if ((READ_DMAREG(esc, DMA_CMD) & DMACMD_CMD) != DMACMD_IDLE)
634 		return 1;
635 	return 0;
636 }
637