xref: /src/sys/dev/ic/ahcisata_core.c

/*	$NetBSD: ahcisata_core.c,v 1.7 2007/11/12 20:10:32 joerg Exp $	*/

/*
 * Copyright (c) 2006 Manuel Bouyer.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by Manuel Bouyer.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ahcisata_core.c,v 1.7 2007/11/12 20:10:32 joerg Exp $");

#include <sys/types.h>
#include <sys/malloc.h>
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/disklabel.h>
#include <sys/proc.h>

#include <uvm/uvm_extern.h>

#include <dev/ic/wdcreg.h>
#include <dev/ata/atareg.h>
#include <dev/ata/satavar.h>
#include <dev/ata/satareg.h>
#include <dev/ic/ahcisatavar.h>

#ifdef AHCI_DEBUG
int ahcidebug_mask = 0x0;
#endif

void ahci_probe_drive(struct ata_channel *);
void ahci_setup_channel(struct ata_channel *);

int  ahci_ata_bio(struct ata_drive_datas *, struct ata_bio *);
void ahci_reset_drive(struct ata_drive_datas *, int);
void ahci_reset_channel(struct ata_channel *, int);
int  ahci_exec_command(struct ata_drive_datas *, struct ata_command *);
int  ahci_ata_addref(struct ata_drive_datas *);
void ahci_ata_delref(struct ata_drive_datas *);
void ahci_killpending(struct ata_drive_datas *);

void ahci_cmd_start(struct ata_channel *, struct ata_xfer *);
int  ahci_cmd_complete(struct ata_channel *, struct ata_xfer *, int);
void ahci_cmd_done(struct ata_channel *, struct ata_xfer *, int);
void ahci_cmd_kill_xfer(struct ata_channel *, struct ata_xfer *, int) ;
void ahci_bio_start(struct ata_channel *, struct ata_xfer *);
int  ahci_bio_complete(struct ata_channel *, struct ata_xfer *, int);
void ahci_bio_kill_xfer(struct ata_channel *, struct ata_xfer *, int) ;
void ahci_channel_stop(struct ahci_softc *, struct ata_channel *, int);
void ahci_channel_start(struct ahci_softc *, struct ata_channel *);
void ahci_timeout(void *);
int  ahci_dma_setup(struct ata_channel *, int, void *, size_t, int);

#define ATA_DELAY 10000 /* 10s for a drive I/O */

const struct ata_bustype ahci_ata_bustype = {
	SCSIPI_BUSTYPE_ATA,
	ahci_ata_bio,
	ahci_reset_drive,
	ahci_reset_channel,
	ahci_exec_command,
	ata_get_params,
	ahci_ata_addref,
	ahci_ata_delref,
	ahci_killpending
};

void ahci_intr_port(struct ahci_softc *, struct ahci_channel *);

static void ahci_setup_port(struct ahci_softc *sc, int i);

int
ahci_reset(struct ahci_softc *sc)
{
	int i;

	/* reset controller */
	AHCI_WRITE(sc, AHCI_GHC, AHCI_GHC_HR);
	/* wait up to 1s for reset to complete */
	for (i = 0; i < 1000; i++) {
		delay(1000);
		if ((AHCI_READ(sc, AHCI_GHC) & AHCI_GHC_HR) == 0)
			break;
	}
	if ((AHCI_READ(sc, AHCI_GHC) & AHCI_GHC_HR)) {
		aprint_error("%s: reset failed\n", AHCINAME(sc));
		return -1;
	}
	/* enable ahci mode */
	AHCI_WRITE(sc, AHCI_GHC, AHCI_GHC_AE);
	return 0;
}

void
ahci_setup_ports(struct ahci_softc *sc)
{
	u_int32_t ahci_ports;
	int i, port;

	ahci_ports = AHCI_READ(sc, AHCI_PI);
	for (i = 0, port = 0; i < AHCI_MAX_PORTS; i++) {
		if ((ahci_ports & (1 << i)) == 0)
			continue;
		if (port >= sc->sc_atac.atac_nchannels) {
			aprint_error("%s: more ports than announced\n",
			    AHCINAME(sc));
			break;
		}
		ahci_setup_port(sc, i);
	}
}

void
ahci_reprobe_drives(struct ahci_softc *sc)
{
	u_int32_t ahci_ports;
	int i, port;
	struct ahci_channel *achp;
	struct ata_channel *chp;

	ahci_ports = AHCI_READ(sc, AHCI_PI);
	for (i = 0, port = 0; i < AHCI_MAX_PORTS; i++) {
		if ((ahci_ports & (1 << i)) == 0)
			continue;
		if (port >= sc->sc_atac.atac_nchannels) {
			aprint_error("%s: more ports than announced\n",
			    AHCINAME(sc));
			break;
		}
		achp = &sc->sc_channels[i];
		chp = &achp->ata_channel;

		ahci_probe_drive(chp);
	}
}

static void
ahci_setup_port(struct ahci_softc *sc, int i)
{
	struct ahci_channel *achp;

	achp = &sc->sc_channels[i];

	AHCI_WRITE(sc, AHCI_P_CLB(i), achp->ahcic_bus_cmdh);
	AHCI_WRITE(sc, AHCI_P_CLBU(i), 0);
	AHCI_WRITE(sc, AHCI_P_FB(i), achp->ahcic_bus_rfis);
	AHCI_WRITE(sc, AHCI_P_FBU(i), 0);
}

void
ahci_enable_intrs(struct ahci_softc *sc)
{

	/* clear interrupts */
	AHCI_WRITE(sc, AHCI_IS, AHCI_READ(sc, AHCI_IS));
	/* enable interrupts */
	AHCI_WRITE(sc, AHCI_GHC, AHCI_READ(sc, AHCI_GHC) | AHCI_GHC_IE);
}

void
ahci_attach(struct ahci_softc *sc)
{
	u_int32_t ahci_cap, ahci_rev, ahci_ports;
	int i, j, port;
	struct ahci_channel *achp;
	struct ata_channel *chp;
	int error;
	bus_dma_segment_t seg;
	int rseg;
	int dmasize;
	void *cmdhp;
	void *cmdtblp;

	if (ahci_reset(sc) != 0)
		return;

	ahci_cap = AHCI_READ(sc, AHCI_CAP);
	sc->sc_atac.atac_nchannels = (ahci_cap & AHCI_CAP_NPMASK) + 1;
	sc->sc_ncmds = ((ahci_cap & AHCI_CAP_NCS) >> 8) + 1;
	ahci_rev = AHCI_READ(sc, AHCI_VS);
	aprint_normal("%s: AHCI revision ", AHCINAME(sc));
	switch(ahci_rev) {
	case AHCI_VS_10:
		aprint_normal("1.0");
		break;
	case AHCI_VS_11:
		aprint_normal("1.1");
		break;
	default:
		aprint_normal("0x%x", ahci_rev);
		break;
	}

	aprint_normal(", %d ports, %d command slots, features 0x%x\n",
	    sc->sc_atac.atac_nchannels, sc->sc_ncmds,
	    ahci_cap & ~(AHCI_CAP_NPMASK|AHCI_CAP_NCS));
	sc->sc_atac.atac_cap = ATAC_CAP_DATA16 | ATAC_CAP_DMA | ATAC_CAP_UDMA;
	sc->sc_atac.atac_pio_cap = 4;
	sc->sc_atac.atac_dma_cap = 2;
	sc->sc_atac.atac_udma_cap = 6;
	sc->sc_atac.atac_channels = sc->sc_chanarray;
	sc->sc_atac.atac_atapibus_attach = NULL; /* XXX */
	sc->sc_atac.atac_probe = ahci_probe_drive;
	sc->sc_atac.atac_bustype_ata = &ahci_ata_bustype;
	sc->sc_atac.atac_set_modes = ahci_setup_channel;

	dmasize =
	    (AHCI_RFIS_SIZE + AHCI_CMDH_SIZE) * sc->sc_atac.atac_nchannels;
	error = bus_dmamem_alloc(sc->sc_dmat, dmasize, PAGE_SIZE, 0,
	    &seg, 1, &rseg, BUS_DMA_NOWAIT);
	if (error) {
		aprint_error("%s: unable to allocate command header memory"
		    ", error=%d\n", AHCINAME(sc), error);
		return;
	}
	error = bus_dmamem_map(sc->sc_dmat, &seg, rseg, dmasize,
	    &cmdhp, BUS_DMA_NOWAIT|BUS_DMA_COHERENT);
	if (error) {
		aprint_error("%s: unable to map command header memory"
		    ", error=%d\n", AHCINAME(sc), error);
		return;
	}
	error = bus_dmamap_create(sc->sc_dmat, dmasize, 1, dmasize, 0,
	    BUS_DMA_NOWAIT, &sc->sc_cmd_hdrd);
	if (error) {
		aprint_error("%s: unable to create command header map"
		    ", error=%d\n", AHCINAME(sc), error);
		return;
	}
	error = bus_dmamap_load(sc->sc_dmat, sc->sc_cmd_hdrd,
	    cmdhp, dmasize, NULL, BUS_DMA_NOWAIT);
	if (error) {
		aprint_error("%s: unable to load command header map"
		    ", error=%d\n", AHCINAME(sc), error);
		return;
	}
	sc->sc_cmd_hdr = cmdhp;

	ahci_enable_intrs(sc);

	ahci_ports = AHCI_READ(sc, AHCI_PI);
	for (i = 0, port = 0; i < AHCI_MAX_PORTS; i++) {
		if ((ahci_ports & (1 << i)) == 0)
			continue;
		if (port >= sc->sc_atac.atac_nchannels) {
			aprint_error("%s: more ports than announced\n",
			    AHCINAME(sc));
			break;
		}
		achp = &sc->sc_channels[i];
		chp = (struct ata_channel *)achp;
		sc->sc_chanarray[i] = chp;
		chp->ch_channel = i;
		chp->ch_atac = &sc->sc_atac;
		chp->ch_queue = malloc(sizeof(struct ata_queue),
		    M_DEVBUF, M_NOWAIT);
		if (chp->ch_queue == NULL) {
			aprint_error("%s port %d: can't allocate memory for "
			    "command queue", AHCINAME(sc), i);
			break;
		}
		dmasize = AHCI_CMDTBL_SIZE * sc->sc_ncmds;
		error = bus_dmamem_alloc(sc->sc_dmat, dmasize, PAGE_SIZE, 0,
		    &seg, 1, &rseg, BUS_DMA_NOWAIT);
		if (error) {
			aprint_error("%s: unable to allocate command table "
			    "memory, error=%d\n", AHCINAME(sc), error);
			break;
		}
		error = bus_dmamem_map(sc->sc_dmat, &seg, rseg, dmasize,
		    &cmdtblp, BUS_DMA_NOWAIT|BUS_DMA_COHERENT);
		if (error) {
			aprint_error("%s: unable to map command table memory"
			    ", error=%d\n", AHCINAME(sc), error);
			break;
		}
		error = bus_dmamap_create(sc->sc_dmat, dmasize, 1, dmasize, 0,
		    BUS_DMA_NOWAIT, &achp->ahcic_cmd_tbld);
		if (error) {
			aprint_error("%s: unable to create command table map"
			    ", error=%d\n", AHCINAME(sc), error);
			break;
		}
		error = bus_dmamap_load(sc->sc_dmat, achp->ahcic_cmd_tbld,
		    cmdtblp, dmasize, NULL, BUS_DMA_NOWAIT);
		if (error) {
			aprint_error("%s: unable to load command table map"
			    ", error=%d\n", AHCINAME(sc), error);
			break;
		}
		achp->ahcic_cmdh  = (struct ahci_cmd_header *)
		    ((char *)cmdhp + AHCI_CMDH_SIZE * port);
		achp->ahcic_bus_cmdh = sc->sc_cmd_hdrd->dm_segs[0].ds_addr +
		    AHCI_CMDH_SIZE * port;
		achp->ahcic_rfis = (struct ahci_r_fis *)
		    ((char *)cmdhp +
		     AHCI_CMDH_SIZE * sc->sc_atac.atac_nchannels +
		     AHCI_RFIS_SIZE * port);
		achp->ahcic_bus_rfis = sc->sc_cmd_hdrd->dm_segs[0].ds_addr +
		     AHCI_CMDH_SIZE * sc->sc_atac.atac_nchannels +
		     AHCI_RFIS_SIZE * port;
		AHCIDEBUG_PRINT(("port %d cmdh %p (0x%x) rfis %p (0x%x)\n", i,
		   achp->ahcic_cmdh, (u_int)achp->ahcic_bus_cmdh,
		   achp->ahcic_rfis, (u_int)achp->ahcic_bus_rfis),
		   DEBUG_PROBE);

		for (j = 0; j < sc->sc_ncmds; j++) {
			achp->ahcic_cmd_tbl[j] = (struct ahci_cmd_tbl *)
			    ((char *)cmdtblp + AHCI_CMDTBL_SIZE * j);
			achp->ahcic_bus_cmd_tbl[j] =
			     achp->ahcic_cmd_tbld->dm_segs[0].ds_addr +
			     AHCI_CMDTBL_SIZE * j;
			achp->ahcic_cmdh[j].cmdh_cmdtba =
			    htole32(achp->ahcic_bus_cmd_tbl[j]);
			achp->ahcic_cmdh[j].cmdh_cmdtbau = htole32(0);
			AHCIDEBUG_PRINT(("port %d/%d tbl %p (0x%x)\n", i, j,
			    achp->ahcic_cmd_tbl[j],
			    (u_int)achp->ahcic_bus_cmd_tbl[j]), DEBUG_PROBE);
			/* The xfer DMA map */
			error = bus_dmamap_create(sc->sc_dmat, MAXPHYS,
			    AHCI_NPRD, 0x400000 /* 4MB */, 0,
			    BUS_DMA_NOWAIT | BUS_DMA_ALLOCNOW,
			    &achp->ahcic_datad[j]);
			if (error) {
				aprint_error("%s: couldn't alloc xfer DMA map, "
				    "error=%d\n", AHCINAME(sc), error);
				goto end;
			}
		}
		ahci_setup_port(sc, i);
		chp->ch_ndrive = 1;
		if (bus_space_subregion(sc->sc_ahcit, sc->sc_ahcih,
		    AHCI_P_SSTS(i), 1,  &achp->ahcic_sstatus) != 0) {
			aprint_error("%s: couldn't map channel %d "
			    "sata_status regs\n", AHCINAME(sc), i);
			break;
		}
		if (bus_space_subregion(sc->sc_ahcit, sc->sc_ahcih,
		    AHCI_P_SCTL(i), 1,  &achp->ahcic_scontrol) != 0) {
			aprint_error("%s: couldn't map channel %d "
			    "sata_control regs\n", AHCINAME(sc), i);
			break;
		}
		if (bus_space_subregion(sc->sc_ahcit, sc->sc_ahcih,
		    AHCI_P_SERR(i), 1,  &achp->ahcic_serror) != 0) {
			aprint_error("%s: couldn't map channel %d "
			    "sata_error regs\n", AHCINAME(sc), i);
			break;
		}
		ata_channel_attach(chp);
		port++;
end:
		continue;
	}
}

int
ahci_intr(void *v)
{
	struct ahci_softc *sc = v;
	u_int32_t is;
	int i, r = 0;

	while ((is = AHCI_READ(sc, AHCI_IS))) {
		AHCIDEBUG_PRINT(("%s ahci_intr 0x%x\n", AHCINAME(sc), is),
		    DEBUG_INTR);
		r = 1;
		AHCI_WRITE(sc, AHCI_IS, is);
		for (i = 0; i < AHCI_MAX_PORTS; i++)
			if (is & (1 << i))
				ahci_intr_port(sc, &sc->sc_channels[i]);
	}
	return r;
}

void
ahci_intr_port(struct ahci_softc *sc, struct ahci_channel *achp)
{
	u_int32_t is, tfd;
	struct ata_channel *chp = &achp->ata_channel;
	struct ata_xfer *xfer = chp->ch_queue->active_xfer;
	int slot;

	is = AHCI_READ(sc, AHCI_P_IS(chp->ch_channel));
	AHCI_WRITE(sc, AHCI_P_IS(chp->ch_channel), is);
	AHCIDEBUG_PRINT(("ahci_intr_port %s port %d is 0x%x CI 0x%x\n", AHCINAME(sc),
	    chp->ch_channel, is, AHCI_READ(sc, AHCI_P_CI(chp->ch_channel))),
	    DEBUG_INTR);

	if (is & (AHCI_P_IX_TFES | AHCI_P_IX_HBFS | AHCI_P_IX_IFS |
	    AHCI_P_IX_OFS | AHCI_P_IX_UFS)) {
		slot = (AHCI_READ(sc, AHCI_P_CMD(chp->ch_channel))
			& AHCI_P_CMD_CCS_MASK) >> AHCI_P_CMD_CCS_SHIFT;
		if ((achp->ahcic_cmds_active & (1 << slot)) == 0)
			return;
		/* stop channel */
		ahci_channel_stop(sc, chp, 0);
		if (slot != 0) {
			printf("ahci_intr_port: slot %d\n", slot);
			panic("ahci_intr_port");
		}
		if (is & AHCI_P_IX_TFES) {
			tfd = AHCI_READ(sc, AHCI_P_TFD(chp->ch_channel));
			chp->ch_error =
			    (tfd & AHCI_P_TFD_ERR_MASK) >> AHCI_P_TFD_ERR_SHIFT;
			chp->ch_status = (tfd & 0xff);
		} else {
			/* emulate a CRC error */
			chp->ch_error = WDCE_CRC;
			chp->ch_status = WDCS_ERR;
		}
		xfer->c_intr(chp, xfer, is);
		/* if channel has not been restarted, do it now */
		if ((AHCI_READ(sc, AHCI_P_CMD(chp->ch_channel)) & AHCI_P_CMD_CR)
		    == 0)
			ahci_channel_start(sc, chp);
	} else {
		slot = 0; /* XXX */
		is = AHCI_READ(sc, AHCI_P_IS(chp->ch_channel));
		AHCIDEBUG_PRINT(("ahci_intr_port port %d is 0x%x act 0x%x CI 0x%x\n",
		    chp->ch_channel, is, achp->ahcic_cmds_active,
		    AHCI_READ(sc, AHCI_P_CI(chp->ch_channel))), DEBUG_INTR);
		if ((achp->ahcic_cmds_active & (1 << slot)) == 0)
			return;
		if ((AHCI_READ(sc, AHCI_P_CI(chp->ch_channel)) & (1 << slot))
		    == 0) {
			xfer->c_intr(chp, xfer, 0);
		}
	}
}

void
ahci_reset_drive(struct ata_drive_datas *drvp, int flags)
{
	struct ata_channel *chp = drvp->chnl_softc;
	ata_reset_channel(chp, flags);
	return;
}

void
ahci_reset_channel(struct ata_channel *chp, int flags)
{
	struct ahci_softc *sc = (struct ahci_softc *)chp->ch_atac;
	struct ahci_channel *achp = (struct ahci_channel *)chp;

	ahci_channel_stop(sc, chp, flags);
	if (sata_reset_interface(chp, sc->sc_ahcit, achp->ahcic_scontrol,
	    achp->ahcic_sstatus) != SStatus_DET_DEV) {
		printf("%s: port reset failed\n", AHCINAME(sc));
		/* XXX and then ? */
	}
	AHCI_WRITE(sc, AHCI_P_SERR(chp->ch_channel),
	    AHCI_READ(sc, AHCI_P_SERR(chp->ch_channel)));
	if (chp->ch_queue->active_xfer) {
		chp->ch_queue->active_xfer->c_kill_xfer(chp,
		    chp->ch_queue->active_xfer, KILL_RESET);
	}
	ahci_channel_start(sc, chp);
	return;
}

int
ahci_ata_addref(struct ata_drive_datas *drvp)
{
	return 0;
}

void
ahci_ata_delref(struct ata_drive_datas *drvp)
{
	return;
}

void
ahci_killpending(struct ata_drive_datas *drvp)
{
	return;
}

void
ahci_probe_drive(struct ata_channel *chp)
{
	struct ahci_softc *sc = (struct ahci_softc *)chp->ch_atac;
	struct ahci_channel *achp = (struct ahci_channel *)chp;
	int i, s;
	u_int32_t sig;

	/* XXX This should be done by other code. */
	for (i = 0; i < chp->ch_ndrive; i++) {
		chp->ch_drive[i].chnl_softc = chp;
		chp->ch_drive[i].drive = i;
	}

	/* bring interface up, power up and spin up device */
	AHCI_WRITE(sc, AHCI_P_CMD(chp->ch_channel),
	    AHCI_P_CMD_ICC_AC | AHCI_P_CMD_POD | AHCI_P_CMD_SUD);
	/* reset the PHY and bring online */
	switch (sata_reset_interface(chp, sc->sc_ahcit, achp->ahcic_scontrol,
	    achp->ahcic_sstatus)) {
	case SStatus_DET_DEV:
		AHCI_WRITE(sc, AHCI_P_SERR(chp->ch_channel),
		    AHCI_READ(sc, AHCI_P_SERR(chp->ch_channel)));
		sig = AHCI_READ(sc, AHCI_P_SIG(chp->ch_channel));
		AHCIDEBUG_PRINT(("%s: port %d: sig=0x%x CMD=0x%x\n",
		    AHCINAME(sc), chp->ch_channel, sig,
		    AHCI_READ(sc, AHCI_P_CMD(chp->ch_channel))), DEBUG_PROBE);
		/*
		 * scnt and sn are supposed to be 0x1 for ATAPI, but in some
		 * cases we get wrong values here, so ignore it.
		 */
		s = splbio();
		if ((sig & 0xffff0000) == 0xeb140000) {
			aprint_error("%s port %d: ATAPI device ignored\n",
			    AHCINAME(sc), chp->ch_channel);
			chp->ch_drive[0].drive_flags |= 0 /* DRIVE_ATAPI XXX */;
		} else
			chp->ch_drive[0].drive_flags |= DRIVE_ATA;
		splx(s);
		/* enable interrupts */
		AHCI_WRITE(sc, AHCI_P_IE(chp->ch_channel),
		    AHCI_P_IX_TFES | AHCI_P_IX_HBFS | AHCI_P_IX_IFS |
		    AHCI_P_IX_OFS | AHCI_P_IX_DPS | AHCI_P_IX_UFS |
		    AHCI_P_IX_DHRS);
		/* and start operations */
		ahci_channel_start(sc, chp);
		break;

	default:
		break;
	}
}

void
ahci_setup_channel(struct ata_channel *chp)
{
	return;
}

int
ahci_exec_command(struct ata_drive_datas *drvp, struct ata_command *ata_c)
{
	struct ata_channel *chp = drvp->chnl_softc;
	struct ata_xfer *xfer;
	int ret;
	int s;

	struct ahci_softc *sc = (struct ahci_softc *)chp->ch_atac;
	AHCIDEBUG_PRINT(("ahci_exec_command port %d CI 0x%x\n",
	    chp->ch_channel, AHCI_READ(sc, AHCI_P_CI(chp->ch_channel))),
	    DEBUG_XFERS);
	xfer = ata_get_xfer(ata_c->flags & AT_WAIT ? ATAXF_CANSLEEP :
	    ATAXF_NOSLEEP);
	if (xfer == NULL) {
		return ATACMD_TRY_AGAIN;
	}
	if (ata_c->flags & AT_POLL)
		xfer->c_flags |= C_POLL;
	if (ata_c->flags & AT_WAIT)
		xfer->c_flags |= C_WAIT;
	xfer->c_drive = drvp->drive;
	xfer->c_databuf = ata_c->data;
	xfer->c_bcount = ata_c->bcount;
	xfer->c_cmd = ata_c;
	xfer->c_start = ahci_cmd_start;
	xfer->c_intr = ahci_cmd_complete;
	xfer->c_kill_xfer = ahci_cmd_kill_xfer;
	s = splbio();
	ata_exec_xfer(chp, xfer);
#ifdef DIAGNOSTIC
	if ((ata_c->flags & AT_POLL) != 0 &&
	    (ata_c->flags & AT_DONE) == 0)
		panic("ahci_exec_command: polled command not done");
#endif
	if (ata_c->flags & AT_DONE) {
		ret = ATACMD_COMPLETE;
	} else {
		if (ata_c->flags & AT_WAIT) {
			while ((ata_c->flags & AT_DONE) == 0) {
				tsleep(ata_c, PRIBIO, "ahcicmd", 0);
			}
			ret = ATACMD_COMPLETE;
		} else {
			ret = ATACMD_QUEUED;
		}
	}
	splx(s);
	return ret;
}

void
ahci_cmd_start(struct ata_channel *chp, struct ata_xfer *xfer)
{
	struct ahci_softc *sc = (struct ahci_softc *)chp->ch_atac;
	struct ahci_channel *achp = (struct ahci_channel *)chp;
	struct ata_command *ata_c = xfer->c_cmd;
	int slot = 0 /* XXX slot */;
	struct ahci_cmd_tbl *cmd_tbl;
	struct ahci_cmd_header *cmd_h;
	u_int8_t *fis;
	int i;
	int channel = chp->ch_channel;

	AHCIDEBUG_PRINT(("ahci_cmd_start CI 0x%x\n",
	    AHCI_READ(sc, AHCI_P_CI(chp->ch_channel))), DEBUG_XFERS);

	cmd_tbl = achp->ahcic_cmd_tbl[slot];
	AHCIDEBUG_PRINT(("%s port %d tbl %p\n", AHCINAME(sc), chp->ch_channel,
	      cmd_tbl), DEBUG_XFERS);
	fis = cmd_tbl->cmdt_cfis;

	fis[0] = 0x27;  /* host to device */
	fis[1] = 0x80;  /* command FIS */
	fis[2] = ata_c->r_command;
	fis[3] = ata_c->r_features;
	fis[4] = ata_c->r_sector;
	fis[5] = ata_c->r_cyl & 0xff;
	fis[6] = (ata_c->r_cyl >> 8) & 0xff;
	fis[7] = ata_c->r_head & 0x0f;
	fis[8] = 0;
	fis[9] = 0;
	fis[10] = 0;
	fis[11] = 0;
	fis[12] = ata_c->r_count;
	fis[13] = 0;
	fis[14] = 0;
	fis[15] = WDCTL_4BIT;
	fis[16] = 0;
	fis[17] = 0;
	fis[18] = 0;
	fis[19] = 0;

	cmd_h = &achp->ahcic_cmdh[slot];
	AHCIDEBUG_PRINT(("%s port %d header %p\n", AHCINAME(sc),
	    chp->ch_channel, cmd_h), DEBUG_XFERS);
	if (ahci_dma_setup(chp, slot,
	    (ata_c->flags & (AT_READ|AT_WRITE)) ? ata_c->data : NULL,
	    ata_c->bcount,
	    (ata_c->flags & AT_READ) ? BUS_DMA_READ : BUS_DMA_WRITE)) {
		ata_c->flags |= AT_DF;
		ahci_cmd_complete(chp, xfer, slot);
		return;
	}
	cmd_h->cmdh_flags = htole16(
	    ((ata_c->flags & AT_WRITE) ? AHCI_CMDH_F_WR : 0) |
	    20 /* fis lenght */ / 4);
	cmd_h->cmdh_prdbc = 0;
	AHCI_CMDH_SYNC(sc, achp, slot,
	    BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);

	if (ata_c->flags & AT_POLL) {
		/* polled command, disable interrupts */
		AHCI_WRITE(sc, AHCI_GHC,
		    AHCI_READ(sc, AHCI_GHC) & ~AHCI_GHC_IE);
	}
	chp->ch_flags |= ATACH_IRQ_WAIT;
	chp->ch_status = 0;
	/* start command */
	AHCI_WRITE(sc, AHCI_P_CI(chp->ch_channel), 1 << slot);
	/* and says we started this command */
	achp->ahcic_cmds_active |= 1 << slot;

	if ((ata_c->flags & AT_POLL) == 0) {
		chp->ch_flags |= ATACH_IRQ_WAIT; /* wait for interrupt */
		callout_reset(&chp->ch_callout, mstohz(ata_c->timeout),
		    ahci_timeout, chp);
		return;
	}
	/*
	 * Polled command.
	 */
	for (i = 0; i < ata_c->timeout / 10; i++) {
		if (ata_c->flags & AT_DONE)
			break;
		ahci_intr_port(sc, achp);
		if (ata_c->flags & AT_WAIT)
			tsleep(&xfer, PRIBIO, "ahcipl", mstohz(10));
		else
			delay(10000);
	}
	AHCIDEBUG_PRINT(("%s port %d poll end GHC 0x%x IS 0x%x list 0x%x%x fis 0x%x%x CMD 0x%x CI 0x%x\n", AHCINAME(sc), channel,
	    AHCI_READ(sc, AHCI_GHC), AHCI_READ(sc, AHCI_IS),
	    AHCI_READ(sc, AHCI_P_CLBU(channel)), AHCI_READ(sc, AHCI_P_CLB(channel)),
	    AHCI_READ(sc, AHCI_P_FBU(channel)), AHCI_READ(sc, AHCI_P_FB(channel)),
	    AHCI_READ(sc, AHCI_P_CMD(channel)), AHCI_READ(sc, AHCI_P_CI(channel))),
	    DEBUG_XFERS);
	if ((ata_c->flags & AT_DONE) == 0) {
		ata_c->flags |= AT_TIMEOU;
		ahci_cmd_complete(chp, xfer, slot);
	}
	/* reenable interrupts */
	AHCI_WRITE(sc, AHCI_GHC, AHCI_READ(sc, AHCI_GHC) | AHCI_GHC_IE);
}

void
ahci_cmd_kill_xfer(struct ata_channel *chp, struct ata_xfer *xfer, int reason)
{
	struct ata_command *ata_c = xfer->c_cmd;
	AHCIDEBUG_PRINT(("ahci_cmd_kill_xfer channel %d\n", chp->ch_channel),
	    DEBUG_FUNCS);

	switch (reason) {
	case KILL_GONE:
		ata_c->flags |= AT_GONE;
		break;
	case KILL_RESET:
		ata_c->flags |= AT_RESET;
		break;
	default:
		printf("ahci_cmd_kill_xfer: unknown reason %d\n", reason);
		panic("ahci_cmd_kill_xfer");
	}
	ahci_cmd_done(chp, xfer, 0 /* XXX slot */);
}

int
ahci_cmd_complete(struct ata_channel *chp, struct ata_xfer *xfer, int is)
{
	int slot = 0; /* XXX slot */
	struct ata_command *ata_c = xfer->c_cmd;
	struct ahci_softc *sc = (struct ahci_softc *)chp->ch_atac;

	AHCIDEBUG_PRINT(("ahci_cmd_complete channel %d CMD 0x%x CI 0x%x\n",
	    chp->ch_channel, AHCI_READ(sc, AHCI_P_CMD(chp->ch_channel)),
	    AHCI_READ(sc, AHCI_P_CI(chp->ch_channel))),
	    DEBUG_FUNCS);
	chp->ch_flags &= ~ATACH_IRQ_WAIT;
	if (xfer->c_flags & C_TIMEOU) {
		ata_c->flags |= AT_TIMEOU;
	} else
		callout_stop(&chp->ch_callout);

	chp->ch_queue->active_xfer = NULL;

	if (chp->ch_drive[xfer->c_drive].drive_flags & DRIVE_WAITDRAIN) {
		ahci_cmd_kill_xfer(chp, xfer, KILL_GONE);
		chp->ch_drive[xfer->c_drive].drive_flags &= ~DRIVE_WAITDRAIN;
		wakeup(&chp->ch_queue->active_xfer);
		return 0;
	}
	if (is) {
		ata_c->r_head = 0;
		ata_c->r_count = 0;
		ata_c->r_sector = 0;
		ata_c->r_cyl = 0;
		if (chp->ch_status & WDCS_BSY) {
			ata_c->flags |= AT_TIMEOU;
		} else if (chp->ch_status & WDCS_ERR) {
			ata_c->r_error = chp->ch_error;
			ata_c->flags |= AT_ERROR;
		}
	}
	ahci_cmd_done(chp, xfer, slot);
	return 0;
}

void
ahci_cmd_done(struct ata_channel *chp, struct ata_xfer *xfer, int slot)
{
	struct ahci_softc *sc = (struct ahci_softc *)chp->ch_atac;
	struct ahci_channel *achp = (struct ahci_channel *)chp;
	struct ata_command *ata_c = xfer->c_cmd;

	AHCIDEBUG_PRINT(("ahci_cmd_done channel %d\n", chp->ch_channel),
	    DEBUG_FUNCS);

	/* this comamnd is not active any more */
	achp->ahcic_cmds_active &= ~(1 << slot);

	if (ata_c->flags & (AT_READ|AT_WRITE)) {
		bus_dmamap_sync(sc->sc_dmat, achp->ahcic_datad[slot], 0,
		    achp->ahcic_datad[slot]->dm_mapsize,
		    (ata_c->flags & AT_READ) ? BUS_DMASYNC_POSTREAD :
		    BUS_DMASYNC_POSTWRITE);
		bus_dmamap_unload(sc->sc_dmat, achp->ahcic_datad[slot]);
	}

	AHCI_CMDH_SYNC(sc, achp, slot,
	    BUS_DMASYNC_POSTREAD | BUS_DMASYNC_POSTWRITE);

	ata_c->flags |= AT_DONE;
	if (achp->ahcic_cmdh[slot].cmdh_prdbc)
		ata_c->flags |= AT_XFDONE;

	ata_free_xfer(chp, xfer);
	if (ata_c->flags & AT_WAIT)
		wakeup(ata_c);
	else if (ata_c->callback)
		ata_c->callback(ata_c->callback_arg);
	atastart(chp);
	return;
}

int
ahci_ata_bio(struct ata_drive_datas *drvp, struct ata_bio *ata_bio)
{
	struct ata_channel *chp = drvp->chnl_softc;
	struct ata_xfer *xfer;

	struct ahci_softc *sc = (struct ahci_softc *)chp->ch_atac;
	AHCIDEBUG_PRINT(("ahci_ata_bio port %d CI 0x%x\n",
	    chp->ch_channel, AHCI_READ(sc, AHCI_P_CI(chp->ch_channel))),
	    DEBUG_XFERS);
	xfer = ata_get_xfer(ATAXF_NOSLEEP);
	if (xfer == NULL) {
		return ATACMD_TRY_AGAIN;
	}
	if (ata_bio->flags & ATA_POLL)
		xfer->c_flags |= C_POLL;
	xfer->c_drive = drvp->drive;
	xfer->c_cmd = ata_bio;
	xfer->c_databuf = ata_bio->databuf;
	xfer->c_bcount = ata_bio->bcount;
	xfer->c_start = ahci_bio_start;
	xfer->c_intr = ahci_bio_complete;
	xfer->c_kill_xfer = ahci_bio_kill_xfer;
	ata_exec_xfer(chp, xfer);
	return (ata_bio->flags & ATA_ITSDONE) ? ATACMD_COMPLETE : ATACMD_QUEUED;
}

void
ahci_bio_start(struct ata_channel *chp, struct ata_xfer *xfer)
{
	struct ahci_softc *sc = (struct ahci_softc *)chp->ch_atac;
	struct ahci_channel *achp = (struct ahci_channel *)chp;
	struct ata_bio *ata_bio = xfer->c_cmd;
	int slot = 0 /* XXX slot */;
	struct ahci_cmd_tbl *cmd_tbl;
	struct ahci_cmd_header *cmd_h;
	u_int8_t *fis;
	int i, nblks;
	int channel = chp->ch_channel;

	AHCIDEBUG_PRINT(("ahci_bio_start CI 0x%x\n",
	    AHCI_READ(sc, AHCI_P_CI(chp->ch_channel))), DEBUG_XFERS);

	nblks = xfer->c_bcount / ata_bio->lp->d_secsize;

	cmd_tbl = achp->ahcic_cmd_tbl[slot];
	AHCIDEBUG_PRINT(("%s port %d tbl %p\n", AHCINAME(sc), chp->ch_channel,
	      cmd_tbl), DEBUG_XFERS);
	fis = cmd_tbl->cmdt_cfis;

	fis[0] = 0x27;  /* host to device */
	fis[1] = 0x80;  /* command FIS */
	if (ata_bio->flags & ATA_LBA48) {
		fis[2] = (ata_bio->flags & ATA_READ) ?
		    WDCC_READDMA_EXT : WDCC_WRITEDMA_EXT;
	} else {
		fis[2] =
		    (ata_bio->flags & ATA_READ) ? WDCC_READDMA : WDCC_WRITEDMA;
	}
	fis[3] = 0; /* features */
	fis[4] = ata_bio->blkno & 0xff;
	fis[5] = (ata_bio->blkno >> 8) & 0xff;
	fis[6] = (ata_bio->blkno >> 16) & 0xff;
	if (ata_bio->flags & ATA_LBA48) {
		fis[7] = WDSD_LBA;
		fis[8] = (ata_bio->blkno >> 24) & 0xff;
		fis[9] = (ata_bio->blkno >> 32) & 0xff;
		fis[10] = (ata_bio->blkno >> 40) & 0xff;
	} else {
		fis[7] = ((ata_bio->blkno >> 24) & 0x0f) | WDSD_LBA;
		fis[8] = 0;
		fis[9] = 0;
		fis[10] = 0;
	}
	fis[11] = 0; /* ext features */
	fis[12] = nblks & 0xff;
	fis[13] = (ata_bio->flags & ATA_LBA48) ?
	    ((nblks >> 8) & 0xff) : 0;
	fis[14] = 0;
	fis[15] = WDCTL_4BIT;
	fis[16] = 0;
	fis[17] = 0;
	fis[18] = 0;
	fis[19] = 0;

	cmd_h = &achp->ahcic_cmdh[slot];
	AHCIDEBUG_PRINT(("%s port %d header %p\n", AHCINAME(sc),
	    chp->ch_channel, cmd_h), DEBUG_XFERS);
	if (ahci_dma_setup(chp, slot, ata_bio->databuf, ata_bio->bcount,
	    (ata_bio->flags & ATA_READ) ? BUS_DMA_READ : BUS_DMA_WRITE)) {
		ata_bio->error = ERR_DMA;
		ata_bio->r_error = 0;
		ahci_bio_complete(chp, xfer, slot);
		return;
	}
	cmd_h->cmdh_flags = htole16(
	    ((ata_bio->flags & ATA_READ) ? 0 :  AHCI_CMDH_F_WR) |
	    20 /* fis lenght */ / 4);
	cmd_h->cmdh_prdbc = 0;
	AHCI_CMDH_SYNC(sc, achp, slot,
	    BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);

	if (xfer->c_flags & C_POLL) {
		/* polled command, disable interrupts */
		AHCI_WRITE(sc, AHCI_GHC,
		    AHCI_READ(sc, AHCI_GHC) & ~AHCI_GHC_IE);
	}
	chp->ch_flags |= ATACH_IRQ_WAIT;
	chp->ch_status = 0;
	/* start command */
	AHCI_WRITE(sc, AHCI_P_CI(chp->ch_channel), 1 << slot);
	/* and says we started this command */
	achp->ahcic_cmds_active |= 1 << slot;

	if ((xfer->c_flags & C_POLL) == 0) {
		chp->ch_flags |= ATACH_IRQ_WAIT; /* wait for interrupt */
		callout_reset(&chp->ch_callout, mstohz(ATA_DELAY),
		    ahci_timeout, chp);
		return;
	}
	/*
	 * Polled command.
	 */
	for (i = 0; i < ATA_DELAY / 10; i++) {
		if (ata_bio->flags & ATA_ITSDONE)
			break;
		ahci_intr_port(sc, achp);
		if (ata_bio->flags & ATA_NOSLEEP)
			delay(10000);
		else
			tsleep(&xfer, PRIBIO, "ahcipl", mstohz(10));
	}
	AHCIDEBUG_PRINT(("%s port %d poll end GHC 0x%x IS 0x%x list 0x%x%x fis 0x%x%x CMD 0x%x CI 0x%x\n", AHCINAME(sc), channel,
	    AHCI_READ(sc, AHCI_GHC), AHCI_READ(sc, AHCI_IS),
	    AHCI_READ(sc, AHCI_P_CLBU(channel)), AHCI_READ(sc, AHCI_P_CLB(channel)),
	    AHCI_READ(sc, AHCI_P_FBU(channel)), AHCI_READ(sc, AHCI_P_FB(channel)),
	    AHCI_READ(sc, AHCI_P_CMD(channel)), AHCI_READ(sc, AHCI_P_CI(channel))),
	    DEBUG_XFERS);
	if ((ata_bio->flags & ATA_ITSDONE) == 0) {
		ata_bio->error = TIMEOUT;
		ahci_bio_complete(chp, xfer, slot);
	}
	/* reenable interrupts */
	AHCI_WRITE(sc, AHCI_GHC, AHCI_READ(sc, AHCI_GHC) | AHCI_GHC_IE);
}

void
ahci_bio_kill_xfer(struct ata_channel *chp, struct ata_xfer *xfer, int reason)
{
	int slot = 0;  /* XXX slot */
	int drive = xfer->c_drive;
	struct ata_bio *ata_bio = xfer->c_cmd;
	struct ahci_channel *achp = (struct ahci_channel *)chp;
	AHCIDEBUG_PRINT(("ahci_bio_kill_xfer channel %d\n", chp->ch_channel),
	    DEBUG_FUNCS);

	achp->ahcic_cmds_active &= ~(1 << slot);
	ata_free_xfer(chp, xfer);
	ata_bio->flags |= ATA_ITSDONE;
	switch (reason) {
	case KILL_GONE:
		ata_bio->error = ERR_NODEV;
		break;
	case KILL_RESET:
		ata_bio->error = ERR_RESET;
		break;
	default:
		printf("ahci_bio_kill_xfer: unknown reason %d\n", reason);
		panic("ahci_bio_kill_xfer");
	}
	ata_bio->r_error = WDCE_ABRT;
	(*chp->ch_drive[drive].drv_done)(chp->ch_drive[drive].drv_softc);
}

int
ahci_bio_complete(struct ata_channel *chp, struct ata_xfer *xfer, int is)
{
	int slot = 0; /* XXX slot */
	struct ata_bio *ata_bio = xfer->c_cmd;
	int drive = xfer->c_drive;
	struct ahci_channel *achp = (struct ahci_channel *)chp;
	struct ahci_softc *sc = (struct ahci_softc *)chp->ch_atac;

	AHCIDEBUG_PRINT(("ahci_bio_complete channel %d\n", chp->ch_channel),
	    DEBUG_FUNCS);

	achp->ahcic_cmds_active &= ~(1 << slot);
	chp->ch_flags &= ~ATACH_IRQ_WAIT;
	if (xfer->c_flags & C_TIMEOU) {
		ata_bio->error = TIMEOUT;
	} else {
		callout_stop(&chp->ch_callout);
		ata_bio->error = 0;
	}

	chp->ch_queue->active_xfer = NULL;
	bus_dmamap_sync(sc->sc_dmat, achp->ahcic_datad[slot], 0,
	    achp->ahcic_datad[slot]->dm_mapsize,
	    (ata_bio->flags & ATA_READ) ? BUS_DMASYNC_POSTREAD :
	    BUS_DMASYNC_POSTWRITE);
	bus_dmamap_unload(sc->sc_dmat, achp->ahcic_datad[slot]);

	if (chp->ch_drive[xfer->c_drive].drive_flags & DRIVE_WAITDRAIN) {
		ahci_bio_kill_xfer(chp, xfer, KILL_GONE);
		chp->ch_drive[xfer->c_drive].drive_flags &= ~DRIVE_WAITDRAIN;
		wakeup(&chp->ch_queue->active_xfer);
		return 0;
	}
	ata_free_xfer(chp, xfer);
	ata_bio->flags |= ATA_ITSDONE;
	if (chp->ch_status & WDCS_DWF) {
		ata_bio->error = ERR_DF;
	} else if (chp->ch_status & WDCS_ERR) {
		ata_bio->error = ERROR;
		ata_bio->r_error = chp->ch_error;
	} else if (chp->ch_status & WDCS_CORR)
		ata_bio->flags |= ATA_CORR;

	AHCI_CMDH_SYNC(sc, achp, slot,
	    BUS_DMASYNC_POSTREAD | BUS_DMASYNC_POSTWRITE);
	AHCIDEBUG_PRINT(("ahci_bio_complete bcount %ld",
	    ata_bio->bcount), DEBUG_XFERS);
	ata_bio->bcount -= le32toh(achp->ahcic_cmdh[slot].cmdh_prdbc);
	AHCIDEBUG_PRINT((" now %ld\n", ata_bio->bcount), DEBUG_XFERS);
	(*chp->ch_drive[drive].drv_done)(chp->ch_drive[drive].drv_softc);
	atastart(chp);
	return 0;
}

void
ahci_channel_stop(struct ahci_softc *sc, struct ata_channel *chp, int flags)
{
	int i;
	/* stop channel */
	AHCI_WRITE(sc, AHCI_P_CMD(chp->ch_channel),
	    AHCI_READ(sc, AHCI_P_CMD(chp->ch_channel)) & ~AHCI_P_CMD_ST);
	/* wait 1s for channel to stop */
	for (i = 0; i <100; i++) {
		if ((AHCI_READ(sc, AHCI_P_CMD(chp->ch_channel)) & AHCI_P_CMD_CR)
		    == 0)
			break;
		if (flags & AT_WAIT)
			tsleep(&sc, PRIBIO, "ahcirst", mstohz(10));
		else
			delay(10000);
	}
	if (AHCI_READ(sc, AHCI_P_CMD(chp->ch_channel)) & AHCI_P_CMD_CR) {
		printf("%s: channel wouldn't stop\n", AHCINAME(sc));
		/* XXX controller reset ? */
		return;
	}
}

void
ahci_channel_start(struct ahci_softc *sc, struct ata_channel *chp)
{
	/* clear error */
	AHCI_WRITE(sc, AHCI_P_SERR(chp->ch_channel), 0);

	/* and start controller */
	AHCI_WRITE(sc, AHCI_P_CMD(chp->ch_channel),
	    AHCI_P_CMD_ICC_AC | AHCI_P_CMD_POD | AHCI_P_CMD_SUD |
	    AHCI_P_CMD_FRE | AHCI_P_CMD_ST);
}

void
ahci_timeout(void *v)
{
	struct ata_channel *chp = (struct ata_channel *)v;
	struct ata_xfer *xfer = chp->ch_queue->active_xfer;
	int s = splbio();
	AHCIDEBUG_PRINT(("ahci_timeout xfer %p\n", xfer), DEBUG_INTR);
	if ((chp->ch_flags & ATACH_IRQ_WAIT) != 0) {
		xfer->c_flags |= C_TIMEOU;
		xfer->c_intr(chp, xfer, 0);
	}
	splx(s);
}

int
ahci_dma_setup(struct ata_channel *chp, int slot, void *data,
    size_t count, int op)
{
	int error, seg;
	struct ahci_softc *sc = (struct ahci_softc *)chp->ch_atac;
	struct ahci_channel *achp = (struct ahci_channel *)chp;
	struct ahci_cmd_tbl *cmd_tbl;
	struct ahci_cmd_header *cmd_h;

	cmd_h = &achp->ahcic_cmdh[slot];
	cmd_tbl = achp->ahcic_cmd_tbl[slot];

	if (data == NULL) {
		cmd_h->cmdh_prdtl = 0;
		goto end;
	}

	error = bus_dmamap_load(sc->sc_dmat, achp->ahcic_datad[slot],
	    data, count, NULL,
	    BUS_DMA_NOWAIT | BUS_DMA_STREAMING | op);
	if (error) {
		printf("%s port %d: failed to load xfer: %d\n",
		    AHCINAME(sc), chp->ch_channel, error);
		return error;
	}
	bus_dmamap_sync(sc->sc_dmat, achp->ahcic_datad[slot], 0,
	    achp->ahcic_datad[slot]->dm_mapsize,
	    (op == BUS_DMA_READ) ? BUS_DMASYNC_PREREAD : BUS_DMASYNC_PREWRITE);
	for (seg = 0; seg <  achp->ahcic_datad[slot]->dm_nsegs; seg++) {
		cmd_tbl->cmdt_prd[seg].prd_dba = htole32(
		     achp->ahcic_datad[slot]->dm_segs[seg].ds_addr);
		cmd_tbl->cmdt_prd[seg].prd_dbau = 0;
		cmd_tbl->cmdt_prd[seg].prd_dbc = htole32(
		    achp->ahcic_datad[slot]->dm_segs[seg].ds_len - 1);
	}
	cmd_tbl->cmdt_prd[seg - 1].prd_dbc |= htole32(AHCI_PRD_DBC_IPC);
	cmd_h->cmdh_prdtl = htole16(achp->ahcic_datad[slot]->dm_nsegs);
end:
	AHCI_CMDTBL_SYNC(sc, achp, slot, BUS_DMASYNC_PREWRITE);
	return 0;
}