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pcscp.c revision 1.31
      1 /*	$NetBSD: pcscp.c,v 1.31 2005/01/02 12:10:34 tsutsui 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 (at) 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 1.31 2005/01/02 12:10:34 tsutsui 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 int	pcscp_match(struct device *, struct cfdata *, void *);
    108 void	pcscp_attach(struct device *, struct device *, void *);
    109 
    110 CFATTACH_DECL(pcscp, sizeof(struct pcscp_softc),
    111     pcscp_match, pcscp_attach, NULL, NULL);
    112 
    113 /*
    114  * Functions and the switch for the MI code.
    115  */
    116 
    117 u_char	pcscp_read_reg(struct ncr53c9x_softc *, int);
    118 void	pcscp_write_reg(struct ncr53c9x_softc *, int, u_char);
    119 int	pcscp_dma_isintr(struct ncr53c9x_softc *);
    120 void	pcscp_dma_reset(struct ncr53c9x_softc *);
    121 int	pcscp_dma_intr(struct ncr53c9x_softc *);
    122 int	pcscp_dma_setup(struct ncr53c9x_softc *, caddr_t *, size_t *, int,
    123     size_t *);
    124 void	pcscp_dma_go(struct ncr53c9x_softc *);
    125 void	pcscp_dma_stop(struct ncr53c9x_softc *);
    126 int	pcscp_dma_isactive(struct ncr53c9x_softc *);
    127 
    128 struct ncr53c9x_glue pcscp_glue = {
    129 	pcscp_read_reg,
    130 	pcscp_write_reg,
    131 	pcscp_dma_isintr,
    132 	pcscp_dma_reset,
    133 	pcscp_dma_intr,
    134 	pcscp_dma_setup,
    135 	pcscp_dma_go,
    136 	pcscp_dma_stop,
    137 	pcscp_dma_isactive,
    138 	NULL,			/* gl_clear_latched_intr */
    139 };
    140 
    141 int
    142 pcscp_match(struct device *parent, struct cfdata *match, void *aux)
    143 {
    144 	struct pci_attach_args *pa = aux;
    145 
    146 	if (PCI_VENDOR(pa->pa_id) != PCI_VENDOR_AMD)
    147 		return 0;
    148 
    149 	switch (PCI_PRODUCT(pa->pa_id)) {
    150 	case PCI_PRODUCT_AMD_PCSCSI_PCI:
    151 		return 1;
    152 	}
    153 	return 0;
    154 }
    155 
    156 /*
    157  * Attach this instance, and then all the sub-devices
    158  */
    159 void
    160 pcscp_attach(struct device *parent, struct device *self, void *aux)
    161 {
    162 	struct pci_attach_args *pa = aux;
    163 	struct pcscp_softc *esc = (void *)self;
    164 	struct ncr53c9x_softc *sc = &esc->sc_ncr53c9x;
    165 	bus_space_tag_t iot;
    166 	bus_space_handle_t ioh;
    167 	pci_intr_handle_t ih;
    168 	const char *intrstr;
    169 	pcireg_t csr;
    170 	bus_dma_segment_t seg;
    171 	int error, rseg;
    172 	char devinfo[256];
    173 
    174 	pci_devinfo(pa->pa_id, pa->pa_class, 0, devinfo, sizeof(devinfo));
    175 	printf(": %s\n", devinfo);
    176 	printf("%s", sc->sc_dev.dv_xname);
    177 
    178 	if (pci_mapreg_map(pa, IO_MAP_REG, PCI_MAPREG_TYPE_IO, 0,
    179 	    &iot, &ioh, NULL, NULL)) {
    180 		printf(": unable to map registers\n");
    181 		return;
    182 	}
    183 
    184 	sc->sc_glue = &pcscp_glue;
    185 
    186 	esc->sc_st = iot;
    187 	esc->sc_sh = ioh;
    188 	esc->sc_dmat = pa->pa_dmat;
    189 
    190 	csr = pci_conf_read(pa->pa_pc, pa->pa_tag, PCI_COMMAND_STATUS_REG);
    191 	pci_conf_write(pa->pa_pc, pa->pa_tag, PCI_COMMAND_STATUS_REG,
    192 	    csr | PCI_COMMAND_MASTER_ENABLE | PCI_COMMAND_IO_ENABLE);
    193 
    194 	/*
    195 	 * XXX More of this should be in ncr53c9x_attach(), but
    196 	 * XXX should we really poke around the chip that much in
    197 	 * XXX the MI code?  Think about this more...
    198 	 */
    199 
    200 	/*
    201 	 * Set up static configuration info.
    202 	 */
    203 
    204 	/*
    205 	 * XXX should read configuration from EEPROM?
    206 	 *
    207 	 * MI ncr53c9x driver does not support configuration
    208 	 * per each target device, though...
    209 	 */
    210 	sc->sc_id = 7;
    211 	sc->sc_cfg1 = sc->sc_id | NCRCFG1_PARENB;
    212 	sc->sc_cfg2 = NCRCFG2_SCSI2 | NCRCFG2_FE;
    213 	sc->sc_cfg3 = NCRAMDCFG3_IDM | NCRAMDCFG3_FCLK;
    214 	sc->sc_cfg4 = NCRAMDCFG4_GE12NS | NCRAMDCFG4_RADE;
    215 	sc->sc_rev = NCR_VARIANT_AM53C974;
    216 	sc->sc_features = NCR_F_FASTSCSI;
    217 	sc->sc_cfg3_fscsi = NCRAMDCFG3_FSCSI;
    218 	sc->sc_freq = 40; /* MHz */
    219 
    220 	/*
    221 	 * XXX minsync and maxxfer _should_ be set up in MI code,
    222 	 * XXX but it appears to have some dependency on what sort
    223 	 * XXX of DMA we're hooked up to, etc.
    224 	 */
    225 
    226 	/*
    227 	 * This is the value used to start sync negotiations
    228 	 * Note that the NCR register "SYNCTP" is programmed
    229 	 * in "clocks per byte", and has a minimum value of 4.
    230 	 * The SCSI period used in negotiation is one-fourth
    231 	 * of the time (in nanoseconds) needed to transfer one byte.
    232 	 * Since the chip's clock is given in MHz, we have the following
    233 	 * formula: 4 * period = (1000 / freq) * 4
    234 	 */
    235 
    236 	sc->sc_minsync = 1000 / sc->sc_freq;
    237 
    238 	/* Really no limit, but since we want to fit into the TCR... */
    239 	sc->sc_maxxfer = 16 * 1024 * 1024;
    240 
    241 	/*
    242 	 * Create the DMA maps for the data transfers.
    243 	 */
    244 
    245 #define MDL_SEG_SIZE	0x1000 /* 4kbyte per segment */
    246 #define MDL_SEG_OFFSET	0x0FFF
    247 #define MDL_SIZE	(MAXPHYS / MDL_SEG_SIZE + 1) /* no hardware limit? */
    248 
    249 	if (bus_dmamap_create(esc->sc_dmat, MAXPHYS, MDL_SIZE, MDL_SEG_SIZE,
    250 	    MDL_SEG_SIZE, BUS_DMA_NOWAIT, &esc->sc_xfermap)) {
    251 		printf(": can't create DMA maps\n");
    252 		return;
    253 	}
    254 
    255 	/*
    256 	 * Allocate and map memory for the MDL.
    257 	 */
    258 
    259 	if ((error = bus_dmamem_alloc(esc->sc_dmat,
    260 	    sizeof(uint32_t) * MDL_SIZE, PAGE_SIZE, 0, &seg, 1, &rseg,
    261 	    BUS_DMA_NOWAIT)) != 0) {
    262 		printf(": unable to allocate memory for the MDL, error = %d\n",
    263 		    error);
    264 		return;
    265 	}
    266 	if ((error = bus_dmamem_map(esc->sc_dmat, &seg, rseg,
    267 	    sizeof(uint32_t) * MDL_SIZE , (caddr_t *)&esc->sc_mdladdr,
    268 	    BUS_DMA_NOWAIT|BUS_DMA_COHERENT)) != 0) {
    269 		printf(": unable to map the MDL memory, error = %d\n", error);
    270 		return;
    271 	}
    272 	if ((error = bus_dmamap_create(esc->sc_dmat,
    273 	    sizeof(uint32_t) * MDL_SIZE, 1, sizeof(uint32_t) * MDL_SIZE,
    274 	    0, BUS_DMA_NOWAIT, &esc->sc_mdldmap)) != 0) {
    275 		printf(": unable to map_create for the MDL, error = %d\n",
    276 		    error);
    277 		return;
    278 	}
    279 	if ((error = bus_dmamap_load(esc->sc_dmat, esc->sc_mdldmap,
    280 	     esc->sc_mdladdr, sizeof(uint32_t) * MDL_SIZE,
    281 	     NULL, BUS_DMA_NOWAIT)) != 0) {
    282 		printf(": unable to load for the MDL, error = %d\n", error);
    283 		return;
    284 	}
    285 
    286 	/* map and establish interrupt */
    287 	if (pci_intr_map(pa, &ih)) {
    288 		printf(": couldn't map interrupt\n");
    289 		return;
    290 	}
    291 
    292 	intrstr = pci_intr_string(pa->pa_pc, ih);
    293 	esc->sc_ih = pci_intr_establish(pa->pa_pc, ih, IPL_BIO,
    294 	    ncr53c9x_intr, esc);
    295 	if (esc->sc_ih == NULL) {
    296 		printf(": couldn't establish interrupt");
    297 		if (intrstr != NULL)
    298 			printf(" at %s", intrstr);
    299 		printf("\n");
    300 		return;
    301 	}
    302 	if (intrstr != NULL)
    303 		printf(": interrupting at %s\n", intrstr);
    304 
    305 	/* Do the common parts of attachment. */
    306 	printf("%s", sc->sc_dev.dv_xname);
    307 	sc->sc_adapter.adapt_minphys = minphys;
    308 	sc->sc_adapter.adapt_request = ncr53c9x_scsipi_request;
    309 	ncr53c9x_attach(sc);
    310 
    311 	/* Turn on target selection using the `DMA' method */
    312 	sc->sc_features |= NCR_F_DMASELECT;
    313 }
    314 
    315 /*
    316  * Glue functions.
    317  */
    318 
    319 u_char
    320 pcscp_read_reg(struct ncr53c9x_softc *sc, int reg)
    321 {
    322 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
    323 
    324 	return PCSCP_READ_REG(esc, reg);
    325 }
    326 
    327 void
    328 pcscp_write_reg(struct ncr53c9x_softc *sc, int reg, u_char v)
    329 {
    330 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
    331 
    332 	PCSCP_WRITE_REG(esc, reg, v);
    333 }
    334 
    335 int
    336 pcscp_dma_isintr(struct ncr53c9x_softc *sc)
    337 {
    338 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
    339 
    340 	return (PCSCP_READ_REG(esc, NCR_STAT) & NCRSTAT_INT) != 0;
    341 }
    342 
    343 void
    344 pcscp_dma_reset(struct ncr53c9x_softc *sc)
    345 {
    346 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
    347 
    348 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_IDLE);
    349 
    350 	esc->sc_active = 0;
    351 }
    352 
    353 int
    354 pcscp_dma_intr(struct ncr53c9x_softc *sc)
    355 {
    356 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
    357 	int trans, resid, i;
    358 	bus_dmamap_t dmap = esc->sc_xfermap;
    359 	int datain = esc->sc_datain;
    360 	uint32_t dmastat;
    361 	char *p = NULL;
    362 
    363 	dmastat = READ_DMAREG(esc, DMA_STAT);
    364 
    365 	if (dmastat & DMASTAT_ERR) {
    366 		/* XXX not tested... */
    367 		WRITE_DMAREG(esc, DMA_CMD,
    368 		    DMACMD_ABORT | (datain ? DMACMD_DIR : 0));
    369 
    370 		printf("%s: error: DMA error detected; Aborting.\n",
    371 		    sc->sc_dev.dv_xname);
    372 		bus_dmamap_unload(esc->sc_dmat, dmap);
    373 		return -1;
    374 	}
    375 
    376 	if (dmastat & DMASTAT_ABT) {
    377 		/* XXX What should be done? */
    378 		printf("%s: dma_intr: DMA aborted.\n", sc->sc_dev.dv_xname);
    379 		WRITE_DMAREG(esc, DMA_CMD,
    380 		    DMACMD_IDLE | (datain ? DMACMD_DIR : 0));
    381 		esc->sc_active = 0;
    382 		return 0;
    383 	}
    384 
    385 #ifdef DIAGNOSTIC
    386 	/* This is an "assertion" :) */
    387 	if (esc->sc_active == 0)
    388 		panic("pcscp dmaintr: DMA wasn't active");
    389 #endif
    390 
    391 	/* DMA has stopped */
    392 
    393 	esc->sc_active = 0;
    394 
    395 	if (esc->sc_dmasize == 0) {
    396 		/* A "Transfer Pad" operation completed */
    397 		NCR_DMA(("dmaintr: discarded %d bytes (tcl=%d, tcm=%d)\n",
    398 		    PCSCP_READ_REG(esc, NCR_TCL) |
    399 		    (PCSCP_READ_REG(esc, NCR_TCM) << 8),
    400 		    PCSCP_READ_REG(esc, NCR_TCL),
    401 		    PCSCP_READ_REG(esc, NCR_TCM)));
    402 		return 0;
    403 	}
    404 
    405 	resid = 0;
    406 	/*
    407 	 * If a transfer onto the SCSI bus gets interrupted by the device
    408 	 * (e.g. for a SAVEPOINTER message), the data in the FIFO counts
    409 	 * as residual since the ESP counter registers get decremented as
    410 	 * bytes are clocked into the FIFO.
    411 	 */
    412 	if (!datain &&
    413 	    (resid = (PCSCP_READ_REG(esc, NCR_FFLAG) & NCRFIFO_FF)) != 0) {
    414 		NCR_DMA(("pcscp_dma_intr: empty esp FIFO of %d ", resid));
    415 	}
    416 
    417 	if ((sc->sc_espstat & NCRSTAT_TC) == 0) {
    418 		/*
    419 		 * `Terminal count' is off, so read the residue
    420 		 * out of the ESP counter registers.
    421 		 */
    422 		if (datain) {
    423 			resid = PCSCP_READ_REG(esc, NCR_FFLAG) & NCRFIFO_FF;
    424 			while (resid > 1)
    425 				resid =
    426 				    PCSCP_READ_REG(esc, NCR_FFLAG) & NCRFIFO_FF;
    427 			WRITE_DMAREG(esc, DMA_CMD, DMACMD_BLAST | DMACMD_MDL |
    428 			    (datain ? DMACMD_DIR : 0));
    429 
    430 			for (i = 0; i < 0x8000; i++) /* XXX 0x8000 ? */
    431 				if (READ_DMAREG(esc, DMA_STAT) & DMASTAT_BCMP)
    432 					break;
    433 
    434 			/* See the below comments... */
    435 			if (resid)
    436 				p = *esc->sc_dmaaddr;
    437 		}
    438 
    439 		resid += PCSCP_READ_REG(esc, NCR_TCL) |
    440 		    (PCSCP_READ_REG(esc, NCR_TCM) << 8) |
    441 		    (PCSCP_READ_REG(esc, NCR_TCH) << 16);
    442 	} else {
    443 		while ((dmastat & DMASTAT_DONE) == 0)
    444 			dmastat = READ_DMAREG(esc, DMA_STAT);
    445 	}
    446 
    447 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_IDLE | (datain ? DMACMD_DIR : 0));
    448 
    449 	/* sync MDL */
    450 	bus_dmamap_sync(esc->sc_dmat, esc->sc_mdldmap,
    451 	    0, sizeof(uint32_t) * dmap->dm_nsegs, BUS_DMASYNC_POSTWRITE);
    452 	/* sync transfer buffer */
    453 	bus_dmamap_sync(esc->sc_dmat, dmap, 0, dmap->dm_mapsize,
    454 	    datain ? BUS_DMASYNC_POSTREAD : BUS_DMASYNC_POSTWRITE);
    455 	bus_dmamap_unload(esc->sc_dmat, dmap);
    456 
    457 	trans = esc->sc_dmasize - resid;
    458 
    459 	/*
    460 	 * From the technical manual notes:
    461 	 *
    462 	 * `In some odd byte conditions, one residual byte will be left
    463 	 *  in the SCSI FIFO, and the FIFO flags will never count to 0.
    464 	 *  When this happens, the residual byte should be retrieved
    465 	 *  via PIO following completion of the BLAST operation.'
    466 	 */
    467 
    468 	if (p) {
    469 		p += trans;
    470 		*p = PCSCP_READ_REG(esc, NCR_FIFO);
    471 		trans++;
    472 	}
    473 
    474 	if (trans < 0) {			/* transferred < 0 ? */
    475 #if 0
    476 		/*
    477 		 * This situation can happen in perfectly normal operation
    478 		 * if the ESP is reselected while using DMA to select
    479 		 * another target.  As such, don't print the warning.
    480 		 */
    481 		printf("%s: xfer (%d) > req (%d)\n",
    482 		    sc->sc_dev.dv_xname, trans, esc->sc_dmasize);
    483 #endif
    484 		trans = esc->sc_dmasize;
    485 	}
    486 
    487 	NCR_DMA(("dmaintr: tcl=%d, tcm=%d, tch=%d; trans=%d, resid=%d\n",
    488 	    PCSCP_READ_REG(esc, NCR_TCL),
    489 	    PCSCP_READ_REG(esc, NCR_TCM),
    490 	    PCSCP_READ_REG(esc, NCR_TCH),
    491 	    trans, resid));
    492 
    493 	*esc->sc_dmalen -= trans;
    494 	*esc->sc_dmaaddr += trans;
    495 
    496 	return 0;
    497 }
    498 
    499 int
    500 pcscp_dma_setup(struct ncr53c9x_softc *sc, caddr_t *addr, size_t *len,
    501     int datain, size_t *dmasize)
    502 {
    503 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
    504 	bus_dmamap_t dmap = esc->sc_xfermap;
    505 	uint32_t *mdl;
    506 	int error, nseg, seg;
    507 	bus_addr_t s_offset, s_addr;
    508 
    509 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_IDLE | (datain ? DMACMD_DIR : 0));
    510 
    511 	esc->sc_dmaaddr = addr;
    512 	esc->sc_dmalen = len;
    513 	esc->sc_dmasize = *dmasize;
    514 	esc->sc_datain = datain;
    515 
    516 #ifdef DIAGNOSTIC
    517 	if ((*dmasize / MDL_SEG_SIZE) > MDL_SIZE)
    518 		panic("pcscp: transfer size too large");
    519 #endif
    520 
    521 	/*
    522 	 * No need to set up DMA in `Transfer Pad' operation.
    523 	 * (case of *dmasize == 0)
    524 	 */
    525 	if (*dmasize == 0)
    526 		return 0;
    527 
    528 	error = bus_dmamap_load(esc->sc_dmat, dmap, *esc->sc_dmaaddr,
    529 	    *esc->sc_dmalen, NULL,
    530 	    ((sc->sc_nexus->xs->xs_control & XS_CTL_NOSLEEP) ?
    531 	    BUS_DMA_NOWAIT : BUS_DMA_WAITOK) | BUS_DMA_STREAMING |
    532 	    ((sc->sc_nexus->xs->xs_control & XS_CTL_DATA_IN) ?
    533 	     BUS_DMA_READ : BUS_DMA_WRITE));
    534 	if (error) {
    535 		printf("%s: unable to load dmamap, error = %d\n",
    536 		    sc->sc_dev.dv_xname, error);
    537 		return error;
    538 	}
    539 
    540 	/* set transfer length */
    541 	WRITE_DMAREG(esc, DMA_STC, *dmasize);
    542 
    543 	/* set up MDL */
    544 	mdl = esc->sc_mdladdr;
    545 	nseg = dmap->dm_nsegs;
    546 
    547 	/* the first segment is possibly not aligned with 4k MDL boundary */
    548 	s_addr = dmap->dm_segs[0].ds_addr;
    549 	s_offset = s_addr & MDL_SEG_OFFSET;
    550 	s_addr -= s_offset;
    551 
    552 	/* set the first MDL and offset */
    553 	WRITE_DMAREG(esc, DMA_SPA, s_offset);
    554 	*mdl++ = htole32(s_addr);
    555 
    556 	/* the rest dmamap segments are aligned with 4k boundary */
    557 	for (seg = 1; seg < nseg; seg++)
    558 		*mdl++ = htole32(dmap->dm_segs[seg].ds_addr);
    559 
    560 	return 0;
    561 }
    562 
    563 void
    564 pcscp_dma_go(struct ncr53c9x_softc *sc)
    565 {
    566 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
    567 	bus_dmamap_t dmap = esc->sc_xfermap, mdldmap = esc->sc_mdldmap;
    568 	int datain = esc->sc_datain;
    569 
    570 	/* No DMA transfer in Transfer Pad operation */
    571 	if (esc->sc_dmasize == 0)
    572 		return;
    573 
    574 	/* sync transfer buffer */
    575 	bus_dmamap_sync(esc->sc_dmat, dmap, 0, dmap->dm_mapsize,
    576 	    datain ? BUS_DMASYNC_PREREAD : BUS_DMASYNC_PREWRITE);
    577 
    578 	/* sync MDL */
    579 	bus_dmamap_sync(esc->sc_dmat, mdldmap,
    580 	    0, sizeof(uint32_t) * dmap->dm_nsegs, BUS_DMASYNC_PREWRITE);
    581 
    582 	/* set Starting MDL Address */
    583 	WRITE_DMAREG(esc, DMA_SMDLA, mdldmap->dm_segs[0].ds_addr);
    584 
    585 	/* set DMA command register bits */
    586 	/* XXX DMA Transfer Interrupt Enable bit is broken? */
    587 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_IDLE | DMACMD_MDL |
    588 	    /* DMACMD_INTE | */
    589 	    (datain ? DMACMD_DIR : 0));
    590 
    591 	/* issue DMA start command */
    592 	WRITE_DMAREG(esc, DMA_CMD, DMACMD_START | DMACMD_MDL |
    593 	    /* DMACMD_INTE | */
    594 	    (datain ? DMACMD_DIR : 0));
    595 
    596 	esc->sc_active = 1;
    597 }
    598 
    599 void
    600 pcscp_dma_stop(struct ncr53c9x_softc *sc)
    601 {
    602 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
    603 
    604 	/* DMA stop */
    605 	/* XXX What should we do here ? */
    606 	WRITE_DMAREG(esc, DMA_CMD,
    607 	    DMACMD_ABORT | (esc->sc_datain ? DMACMD_DIR : 0));
    608 
    609 	esc->sc_active = 0;
    610 }
    611 
    612 int
    613 pcscp_dma_isactive(struct ncr53c9x_softc *sc)
    614 {
    615 	struct pcscp_softc *esc = (struct pcscp_softc *)sc;
    616 
    617 	/* XXX should check esc->sc_active? */
    618 	if ((READ_DMAREG(esc, DMA_CMD) & DMACMD_CMD) != DMACMD_IDLE)
    619 		return 1;
    620 	return 0;
    621 }
    622