AHCI/SILI - Do manual chipid check to PMs with fake ports

[dragonfly.git] / sys / dev / disk / ahci / ahci_pm.c

/*
 * Copyright (c) 2009 The DragonFly Project.  All rights reserved.
 *
 * This code is derived from software contributed to The DragonFly Project
 * by Matthew Dillon <dillon@backplane.com>
 *
 * 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. Neither the name of The DragonFly Project nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific, prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``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
 * COPYRIGHT HOLDERS OR CONTRIBUTORS 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 "ahci.h"

static void ahci_pm_dummy_done(struct ata_xfer *xa);

int
ahci_pm_port_init(struct ahci_port *ap, struct ata_port *at)
{
        at->at_probe = ATA_PROBE_NEED_HARD_RESET;
        return (0);
}

/*
 * AHCI port multiplier probe.  This routine is run by the hardreset code
 * if it gets past the device detect, whether or not BSY is found to be
 * stuck.
 *
 * We MUST use CLO to properly probe whether the port multiplier exists
 * or not.
 *
 * Return 0 on success, non-zero on failure.
 */
int
ahci_pm_port_probe(struct ahci_port *ap, int orig_error)
{
        struct ahci_cmd_hdr *cmd_slot;
        struct ata_port *at;
        struct ahci_ccb *ccb = NULL;
        u_int8_t        *fis = NULL;
        int             error;
        u_int32_t       cmd;
        int             count;
        int             i;

        count = 2;
retry:
        /*
         * This code is only called from hardreset, which does not
         * high level command processing.  The port should be stopped.
         *
         * Set PMA mode while the port is stopped.
         *
         * NOTE: On retry the port might be running, stopped, or failed.
         */
        ahci_port_stop(ap, 0);
        ap->ap_state = AP_S_NORMAL;
        cmd = ahci_pread(ap, AHCI_PREG_CMD) & ~AHCI_PREG_CMD_ICC;
        if ((cmd & AHCI_PREG_CMD_PMA) == 0) {
                cmd |= AHCI_PREG_CMD_PMA;
                ahci_pwrite(ap, AHCI_PREG_CMD, cmd);
        }

        /*
         * Flush any errors and request CLO unconditionally, then start
         * the port.
         */
        ahci_flush_tfd(ap);
        ahci_port_clo(ap);
        if (ahci_port_start(ap)) {
                kprintf("%s: PMPROBE failed to start port, cannot softreset\n",
                        PORTNAME(ap));
                error = EIO;
                goto err;
        }

        /*
         * Check whether CLO worked
         */
        if (ahci_pwait_clr(ap, AHCI_PREG_TFD,
                               AHCI_PREG_TFD_STS_BSY | AHCI_PREG_TFD_STS_DRQ)) {
                kprintf("%s: PMPROBE CLO %s, need port reset\n",
                        PORTNAME(ap),
                        (ahci_read(ap->ap_sc, AHCI_REG_CAP) & AHCI_REG_CAP_SCLO)
                        ? "failed" : "unsupported");
                error = EBUSY;
                goto err;
        }

        /*
         * Use the error CCB for all commands
         *
         * NOTE!  This CCB is used for both the first and second commands.
         *        The second command must use CCB slot 1 to properly load
         *        the signature.
         */
        ccb = ahci_get_err_ccb(ap);
        ccb->ccb_xa.flags = ATA_F_POLL;
        ccb->ccb_xa.complete = ahci_pm_dummy_done;
        ccb->ccb_xa.at = &ap->ap_ata[15];
        cmd_slot = ccb->ccb_cmd_hdr;
        KKASSERT(ccb->ccb_slot == 1);

        /*
         * Prep the first H2D command with SRST feature & clear busy/reset
         * flags.
         */
        fis = ccb->ccb_cmd_table->cfis;
        bzero(fis, sizeof(ccb->ccb_cmd_table->cfis));
        fis[0] = ATA_FIS_TYPE_H2D;
        fis[1] = 0x0F;                  /* Target 15 */
        fis[15] = ATA_FIS_CONTROL_SRST | ATA_FIS_CONTROL_4BIT;

        cmd_slot->prdtl = 0;
        cmd_slot->flags = htole16(5);   /* FIS length: 5 DWORDS */
        cmd_slot->flags |= htole16(AHCI_CMD_LIST_FLAG_C); /* Clear busy on OK */
        cmd_slot->flags |= htole16(AHCI_CMD_LIST_FLAG_R); /* Reset */
        cmd_slot->flags |= htole16(AHCI_CMD_LIST_FLAG_PMP); /* port 0xF */

        ccb->ccb_xa.state = ATA_S_PENDING;

        if (ahci_poll(ccb, 1000, ahci_quick_timeout) != ATA_S_COMPLETE) {
                kprintf("%s: PMPROBE First FIS failed\n", PORTNAME(ap));
                if (--count) {
                        ahci_put_err_ccb(ccb);
                        goto retry;
                }
                error = EBUSY;
                goto err;
        }
        if (ahci_pwait_clr(ap, AHCI_PREG_TFD,
                               AHCI_PREG_TFD_STS_BSY | AHCI_PREG_TFD_STS_DRQ)) {
                kprintf("%s: PMPROBE Busy after first FIS\n", PORTNAME(ap));
        }

        /*
         * The device may have muffed up the PHY when it reset.
         */
        ahci_os_sleep(100);
        ahci_flush_tfd(ap);
        ahci_pwrite(ap, AHCI_PREG_SERR, -1);
        /* ahci_pm_phy_status(ap, 15, &cmd); */

        /*
         * Prep second D2H command to read status and complete reset sequence
         * AHCI 10.4.1 and "Serial ATA Revision 2.6".  I can't find the ATA
         * Rev 2.6 and it is unclear how the second FIS should be set up
         * from the AHCI document.
         *
         * Give the device 3ms before sending the second FIS.
         *
         * It is unclear which other fields in the FIS are used.  Just zero
         * everything.
         */
        ccb->ccb_xa.flags = ATA_F_POLL;

        bzero(fis, sizeof(ccb->ccb_cmd_table->cfis));
        fis[0] = ATA_FIS_TYPE_H2D;
        fis[1] = 0x0F;
        fis[15] = ATA_FIS_CONTROL_4BIT;

        cmd_slot->prdtl = 0;
        cmd_slot->flags = htole16(5);   /* FIS length: 5 DWORDS */
        cmd_slot->flags |= htole16(AHCI_CMD_LIST_FLAG_PMP); /* port 0xF */

        ccb->ccb_xa.state = ATA_S_PENDING;

        if (ahci_poll(ccb, 5000, ahci_quick_timeout) != ATA_S_COMPLETE) {
                kprintf("%s: PMPROBE Second FIS failed\n", PORTNAME(ap));
                if (--count) {
                        ahci_put_err_ccb(ccb);
                        goto retry;
                }
                error = EBUSY;
                goto err;
        }

        /*
         * What? We succeeded?  Yup, but for some reason the signature
         * is still latched from the original detect (that saw target 0
         * behind the PM), and I don't know how to clear the condition
         * other then by retrying the whole reset sequence.
         */
        if (--count) {
                fis[15] = 0;
                ahci_put_err_ccb(ccb);
                goto retry;
        }

        /*
         * Get the signature.  The caller sets the ap fields.
         */
        if (ahci_port_signature_detect(ap, NULL) == ATA_PORT_T_PM) {
                ap->ap_ata[15].at_probe = ATA_PROBE_GOOD;
                error = 0;
        } else {
                error = EBUSY;
        }

        /*
         * Fall through / clean up the CCB and perform error processing.
         */
err:
        if (ccb != NULL)
                ahci_put_err_ccb(ccb);

        if (error == 0 && ahci_pm_identify(ap)) {
                kprintf("%s: PM - cannot identify port multiplier\n",
                        PORTNAME(ap));
                error = EBUSY;
        }

        /*
         * If we probed the PM reset the state for the targets behind
         * it so they get probed by the state machine.
         */
        if (error == 0) {
                for (i = 0; i < AHCI_MAX_PMPORTS; ++i) {
                        at = &ap->ap_ata[i];
                        at->at_probe = ATA_PROBE_NEED_INIT;
                        at->at_features |= ATA_PORT_F_RESCAN;
                }
                ap->ap_type = ATA_PORT_T_PM;
                return (0);
        }

        /*
         * If we failed turn off PMA, otherwise identify the port multiplier.
         * CAM will iterate the devices.
         */
        ahci_port_stop(ap, 0);
        ahci_port_clo(ap);
        cmd = ahci_pread(ap, AHCI_PREG_CMD) & ~AHCI_PREG_CMD_ICC;
        cmd &= ~AHCI_PREG_CMD_PMA;
        ahci_pwrite(ap, AHCI_PREG_CMD, cmd);
        ahci_port_init(ap);
        if (orig_error == 0) {
                if (ahci_pwait_clr(ap, AHCI_PREG_TFD,
                            AHCI_PREG_TFD_STS_BSY | AHCI_PREG_TFD_STS_DRQ)) {
                        kprintf("%s: PM probe: port will not come ready\n",
                                PORTNAME(ap));
                        orig_error = EBUSY;
                }
        }
        return(orig_error);
}

/*
 * Identify the port multiplier
 */
int
ahci_pm_identify(struct ahci_port *ap)
{
        u_int32_t chipid;
        u_int32_t rev;
        u_int32_t nports;
        u_int32_t data1;
        u_int32_t data2;
        int       has_dummy_port;

        ap->ap_probe = ATA_PROBE_FAILED;
        if (ahci_pm_read(ap, 15, 0, &chipid))
                goto err;
        if (ahci_pm_read(ap, 15, 1, &rev))
                goto err;
        if (ahci_pm_read(ap, 15, 2, &nports))
                goto err;
        nports &= 0x0000000F;   /* only the low 4 bits */
        ap->ap_probe = ATA_PROBE_GOOD;

        /*
         * Ignore fake port on PMs which have it.  We can probe it but the
         * softreset will probably fail.
         */
        switch(chipid) {
        case 0x37261095:
                has_dummy_port = 1;
                break;
        default:
                has_dummy_port = 0;
                break;
        }
        if (has_dummy_port) {
                if (nports > 1)
                        --nports;
        }

        kprintf("%s: Port multiplier: chip=%08x rev=0x%b nports=%d\n",
                PORTNAME(ap),
                chipid,
                rev, SATA_PFMT_PM_REV,
                nports);
        if (has_dummy_port) {
                kprintf("%s: Port multiplier: Ignoring dummy port #%d\n",
                PORTNAME(ap), nports);
        }
        ap->ap_pmcount = nports;

        if (ahci_pm_read(ap, 15, SATA_PMREG_FEA, &data1)) {
                kprintf("%s: Port multiplier: Warning, "
                        "cannot read feature register\n", PORTNAME(ap));
        } else {
                kprintf("%s: Port multiplier features: 0x%b\n",
                        PORTNAME(ap),
                        data1,
                        SATA_PFMT_PM_FEA);
        }
        if (ahci_pm_read(ap, 15, SATA_PMREG_FEAEN, &data2) == 0) {
                kprintf("%s: Port multiplier defaults: 0x%b\n",
                        PORTNAME(ap),
                        data2,
                        SATA_PFMT_PM_FEA);
        }

        /*
         * Turn on async notification if we support and the PM supports it.
         * This allows the PM to forward async notification events to us and
         * it will also generate an event for target 15 for hot-plug events
         * (or is supposed to anyway).
         */
        if ((ap->ap_sc->sc_cap & AHCI_REG_CAP_SSNTF) &&
            (data1 & SATA_PMFEA_ASYNCNOTIFY)) {
                u_int32_t serr_bits = AHCI_PREG_SERR_DIAG_N |
                                      AHCI_PREG_SERR_DIAG_X;
                data2 |= SATA_PMFEA_ASYNCNOTIFY;
                if (ahci_pm_write(ap, 15, SATA_PMREG_FEAEN, data2)) {
                        kprintf("%s: Port multiplier: AsyncNotify cannot be "
                                "enabled\n", PORTNAME(ap));
                } else if (ahci_pm_write(ap, 15, SATA_PMREG_EEENA, serr_bits)) {
                        kprintf("%s: Port mulltiplier: AsyncNotify unable "
                                "to enable error info bits\n", PORTNAME(ap));
                } else {
                        kprintf("%s: Port multiplier: AsyncNotify enabled\n",
                                PORTNAME(ap));
                }
        }

        return (0);
err:
        kprintf("%s: Port multiplier cannot be identified\n", PORTNAME(ap));
        return (EIO);
}

/*
 * Do a COMRESET sequence on the target behind a port multiplier.
 *
 * If hard is 2 we also cycle the phy on the target.
 *
 * This must be done prior to any softreset or probe attempts on
 * targets behind the port multiplier.
 *
 * Returns 0 on success or an error.
 */
int
ahci_pm_hardreset(struct ahci_port *ap, int target, int hard)
{
        struct ata_port *at;
        u_int32_t data;
        int loop;
        int error = EIO;

        at = &ap->ap_ata[target];

        /*
         * Turn off power management and kill the phy on the target
         * if requested.  Hold state for 10ms.
         */
        data = AHCI_PREG_SCTL_IPM_DISABLED;
        if (hard == 2)
                data |= AHCI_PREG_SCTL_DET_DISABLE;
        if (ahci_pm_write(ap, target, SATA_PMREG_SERR, -1))
                goto err;
        if (ahci_pm_write(ap, target, SATA_PMREG_SCTL, data))
                goto err;
        ahci_os_sleep(10);

        /*
         * Start transmitting COMRESET.  COMRESET must be sent for at
         * least 1ms.
         */
        at->at_probe = ATA_PROBE_FAILED;
        at->at_type = ATA_PORT_T_NONE;
        data = AHCI_PREG_SCTL_IPM_DISABLED | AHCI_PREG_SCTL_DET_INIT;
        if (AhciForceGen1 & (1 << ap->ap_num)) {
                kprintf("%s.%d: Force 1.5GBits\n", PORTNAME(ap), target);
                data |= AHCI_PREG_SCTL_SPD_GEN1;
        } else {
                data |= AHCI_PREG_SCTL_SPD_ANY;
        }
        if (ahci_pm_write(ap, target, SATA_PMREG_SCTL, data))
                goto err;

        /*
         * It takes about 100ms for the DET logic to settle down,
         * from trial and error testing.  If this is too short
         * the softreset code will fail.
         */
        ahci_os_sleep(100);

        if (ahci_pm_phy_status(ap, target, &data)) {
                kprintf("%s: (A)Cannot clear phy status\n",
                        ATANAME(ap ,at));
        }

        /*
         * Flush any status, then clear DET to initiate negotiation.
         */
        ahci_pm_write(ap, target, SATA_PMREG_SERR, -1);
        data = AHCI_PREG_SCTL_IPM_DISABLED | AHCI_PREG_SCTL_DET_NONE;
        if (ahci_pm_write(ap, target, SATA_PMREG_SCTL, data))
                goto err;

        /*
         * Try to determine if there is a device on the port.
         *
         * Give the device 3/10 second to at least be detected.
         * If we fail clear any pending status since we may have
         * cycled the phy and probably caused another PRCS interrupt.
         */
        for (loop = 3; loop; --loop) {
                if (ahci_pm_read(ap, target, SATA_PMREG_SSTS, &data))
                        goto err;
                if (data & AHCI_PREG_SSTS_DET)
                        break;
                ahci_os_sleep(100);
        }
        if (loop == 0) {
                kprintf("%s.%d: Port appears to be unplugged\n",
                        PORTNAME(ap), target);
                error = ENODEV;
                goto err;
        }

        /*
         * There is something on the port.  Give the device 3 seconds
         * to fully negotiate.
         */
        for (loop = 30; loop; --loop) {
                if (ahci_pm_read(ap, target, SATA_PMREG_SSTS, &data))
                        goto err;
                if ((data & AHCI_PREG_SSTS_DET) == AHCI_PREG_SSTS_DET_DEV)
                        break;
                ahci_os_sleep(100);
        }

        /*
         * Device not detected
         */
        if (loop == 0) {
                kprintf("%s: Device may be powered down\n",
                        PORTNAME(ap));
                error = ENODEV;
                goto err;
        }

        /*
         * Device detected
         */
        kprintf("%s.%d: Device detected data=%08x\n",
                PORTNAME(ap), target, data);
        /*
         * Clear SERR on the target so we get a new NOTIFY event if a hot-plug
         * or hot-unplug occurs.
         */
        ahci_os_sleep(100);

        error = 0;
err:
        at->at_probe = error ? ATA_PROBE_FAILED : ATA_PROBE_NEED_SOFT_RESET;
        return (error);
}

/*
 * AHCI soft reset through port multiplier.
 *
 * This function keeps port communications intact and attempts to generate
 * a reset to the connected device using device commands.  Unlike
 * hard-port operations we can't do fancy stop/starts or stuff like
 * that without messing up other commands that might be running or
 * queued.
 */
int
ahci_pm_softreset(struct ahci_port *ap, int target)
{
        struct ata_port         *at;
        struct ahci_ccb         *ccb;
        struct ahci_cmd_hdr     *cmd_slot;
        u_int8_t                *fis;
        int                     count;
        int                     error;
        u_int32_t               data;
        int                     tried_longer;

        error = EIO;
        at = &ap->ap_ata[target];

        DPRINTF(AHCI_D_VERBOSE, "%s: soft reset\n", PORTNAME(ap));

        count = 2;
        tried_longer = 0;
retry:
        /*
         * Try to clear the phy so we get a good signature, otherwise
         * the PM may not latch a new signature.
         *
         * NOTE: This cannot be safely done between the first and second
         *       softreset FISs.  It's now or never.
         */
#if 1
        if (ahci_pm_phy_status(ap, target, &data)) {
                kprintf("%s: (B)Cannot clear phy status\n",
                        ATANAME(ap ,at));
        }
        ahci_pm_write(ap, target, SATA_PMREG_SERR, -1);
#endif

        /*
         * Prep first D2H command with SRST feature & clear busy/reset flags
         *
         * It is unclear which other fields in the FIS are used.  Just zero
         * everything.
         *
         * When soft-resetting a port behind a multiplier at will be
         * non-NULL, assigning it to the ccb prevents the port interrupt
         * from hard-resetting the port if a problem crops up.
         */
        ccb = ahci_get_err_ccb(ap);
        ccb->ccb_xa.flags = ATA_F_POLL | ATA_F_EXCLUSIVE | ATA_F_AUTOSENSE;
        ccb->ccb_xa.complete = ahci_pm_dummy_done;
        ccb->ccb_xa.at = at;

        fis = ccb->ccb_cmd_table->cfis;
        bzero(fis, sizeof(ccb->ccb_cmd_table->cfis));
        fis[0] = ATA_FIS_TYPE_H2D;
        fis[1] = at->at_target;
        fis[15] = ATA_FIS_CONTROL_SRST|ATA_FIS_CONTROL_4BIT;

        cmd_slot = ccb->ccb_cmd_hdr;
        cmd_slot->prdtl = 0;
        cmd_slot->flags = htole16(5);   /* FIS length: 5 DWORDS */
        cmd_slot->flags |= htole16(AHCI_CMD_LIST_FLAG_C); /* Clear busy on OK */
        cmd_slot->flags |= htole16(AHCI_CMD_LIST_FLAG_R); /* Reset */
        cmd_slot->flags |= htole16(at->at_target <<
                                   AHCI_CMD_LIST_FLAG_PMP_SHIFT);

        ccb->ccb_xa.state = ATA_S_PENDING;

        /*
         * XXX hack to ignore IFS errors which can occur during the target
         *     device's reset.
         *
         *     If an IFS error occurs the target is probably powering up,
         *     so we try for a longer period of time.
         */
        ap->ap_flags |= AP_F_IGNORE_IFS;
        ap->ap_flags &= ~(AP_F_IFS_IGNORED | AP_F_IFS_OCCURED);

        if (ahci_poll(ccb, 1000, ahci_ata_cmd_timeout) != ATA_S_COMPLETE) {
                kprintf("%s: (PM) First FIS failed\n", ATANAME(ap, at));
                if (ap->ap_flags & AP_F_IFS_OCCURED) {
                        if (tried_longer == 0)
                                count += 4;
                        ++tried_longer;
                }
                ahci_put_err_ccb(ccb);
                if (--count)
                        goto retry;
                goto err;
        }

        /*
         * WARNING!  SENSITIVE TIME PERIOD!  WARNING!
         *
         * The first and second FISes are supposed to be back-to-back,
         * I think the idea is to get the second sent and then after
         * the device resets it will send a signature.  Do not delay
         * here and most definitely do not issue any commands to other
         * targets!
         */

        /*
         * Prep second D2H command to read status and complete reset sequence
         * AHCI 10.4.1 and "Serial ATA Revision 2.6".  I can't find the ATA
         * Rev 2.6 and it is unclear how the second FIS should be set up
         * from the AHCI document.
         *
         * Give the device 3ms before sending the second FIS.
         *
         * It is unclear which other fields in the FIS are used.  Just zero
         * everything.
         */
        bzero(fis, sizeof(ccb->ccb_cmd_table->cfis));
        fis[0] = ATA_FIS_TYPE_H2D;
        fis[1] = at->at_target;
        fis[15] = ATA_FIS_CONTROL_4BIT;

        cmd_slot->prdtl = 0;
        cmd_slot->flags = htole16(5);   /* FIS length: 5 DWORDS */
        cmd_slot->flags |= htole16(at->at_target <<
                                   AHCI_CMD_LIST_FLAG_PMP_SHIFT);

        ccb->ccb_xa.state = ATA_S_PENDING;
        ccb->ccb_xa.flags = ATA_F_POLL | ATA_F_EXCLUSIVE | ATA_F_AUTOSENSE;

        if (ahci_poll(ccb, 1000, ahci_ata_cmd_timeout) != ATA_S_COMPLETE) {
                kprintf("%s: (PM) Second FIS failed\n", ATANAME(ap, at));
                ahci_put_err_ccb(ccb);
#if 1
                if (--count)
                        goto retry;
#endif
                goto err;
        }

        ahci_put_err_ccb(ccb);
        ahci_os_sleep(100);
        ahci_pm_write(ap, target, SATA_PMREG_SERR, -1);
        if (ahci_pm_phy_status(ap, target, &data)) {
                kprintf("%s: (C)Cannot clear phy status\n",
                        ATANAME(ap ,at));
        }
        ahci_pm_write(ap, target, SATA_PMREG_SERR, -1);

        /*
         * Do it again, even if we think we got a good result
         */
        if (--count) {
                fis[15] = 0;
                goto retry;
        }

        /*
         * If the softreset is trying to clear a BSY condition after a
         * normal portreset we assign the port type.
         *
         * If the softreset is being run first as part of the ccb error
         * processing code then report if the device signature changed
         * unexpectedly.
         */
        if (at->at_type == ATA_PORT_T_NONE) {
                at->at_type = ahci_port_signature_detect(ap, at);
        } else {
                if (ahci_port_signature_detect(ap, at) != at->at_type) {
                        kprintf("%s: device signature unexpectedly "
                                "changed\n", ATANAME(ap, at));
                        error = EBUSY; /* XXX */
                }
        }
        error = 0;

        /*
         * Who knows what kind of mess occured.  We have exclusive access
         * to the port so try to clean up potential problems.
         */
        ahci_os_sleep(100);
err:
        /*
         * Clear error status so we can detect removal.
         */
        if (ahci_pm_write(ap, target, SATA_PMREG_SERR, -1)) {
                kprintf("%s: ahci_pm_softreset unable to clear SERR\n",
                        ATANAME(ap, at));
                ap->ap_flags &= ~AP_F_IGNORE_IFS;
        }
/*      ahci_pwrite(ap, AHCI_PREG_SERR, -1);*/

        at->at_probe = error ? ATA_PROBE_FAILED : ATA_PROBE_NEED_IDENT;
        return (error);
}


/*
 * Return the phy status for a target behind a port multiplier and
 * reset SATA_PMREG_SERR.
 *
 * Returned bits follow AHCI_PREG_SSTS bits.  The AHCI_PREG_SSTS_SPD
 * bits can be used to determine the link speed and will be 0 if there
 * is no link.
 *
 * 0 is returned if any communications error occurs.
 */
int
ahci_pm_phy_status(struct ahci_port *ap, int target, u_int32_t *datap)
{
        int error;

        error = ahci_pm_read(ap, target, SATA_PMREG_SSTS, datap);
        if (error == 0)
                error = ahci_pm_write(ap, target, SATA_PMREG_SERR, -1);
        if (error)
                *datap = 0;
        return(error);
}

int
ahci_pm_set_feature(struct ahci_port *ap, int feature, int enable)
{
        struct ata_xfer *xa;
        int error;

        xa = ahci_ata_get_xfer(ap, &ap->ap_ata[15]);

        xa->fis->type = ATA_FIS_TYPE_H2D;
        xa->fis->flags = ATA_H2D_FLAGS_CMD | 15;
        xa->fis->command = enable ? ATA_C_SATA_FEATURE_ENA :
                                    ATA_C_SATA_FEATURE_DIS;
        xa->fis->sector_count = feature;
        xa->fis->control = ATA_FIS_CONTROL_4BIT;

        xa->complete = ahci_pm_dummy_done;
        xa->datalen = 0;
        xa->flags = ATA_F_POLL;
        xa->timeout = 1000;

        if (ahci_ata_cmd(xa) == ATA_S_COMPLETE)
                error = 0;
        else
                error = EIO;
        ahci_ata_put_xfer(xa);
        return(error);
}

/*
 * Check that a target is still good.
 */
void
ahci_pm_check_good(struct ahci_port *ap, int target)
{
        struct ata_port *at;
        u_int32_t data;

        /*
         * It looks like we might have to read the EINFO register
         * to allow the PM to generate a new event.
         */
        if (ahci_pm_read(ap, 15, SATA_PMREG_EINFO, &data)) {
                kprintf("%s: Port multiplier EINFO could not be read\n",
                        PORTNAME(ap));
        }

        if (ahci_pm_write(ap, target, SATA_PMREG_SERR, -1)) {
                kprintf("%s: Port multiplier: SERR could not be cleared\n",
                        PORTNAME(ap));
        }

        if (target == CAM_TARGET_WILDCARD || target >= ap->ap_pmcount)
                return;
        at = &ap->ap_ata[target];

        /*
         * If the device needs an init or hard reset also make sure the
         * PHY is turned on.
         */
        if (at->at_probe <= ATA_PROBE_NEED_HARD_RESET) {
                /*kprintf("%s DOHARD\n", ATANAME(ap, at));*/
                ahci_pm_hardreset(ap, target, 1);
        }

        /*
         * Read the detect status
         */
        if (ahci_pm_read(ap, target, SATA_PMREG_SSTS, &data)) {
                kprintf("%s: Unable to access PM SSTS register target %d\n",
                        PORTNAME(ap), target);
                return;
        }
        if ((data & AHCI_PREG_SSTS_DET) != AHCI_PREG_SSTS_DET_DEV) {
                /*kprintf("%s: DETECT %08x\n", ATANAME(ap, at), data);*/
                if (at->at_probe != ATA_PROBE_FAILED) {
                        at->at_probe = ATA_PROBE_FAILED;
                        at->at_type = ATA_PORT_T_NONE;
                        at->at_features |= ATA_PORT_F_RESCAN;
                        kprintf("%s: HOTPLUG (PM) - Device removed\n",
                                ATANAME(ap, at));
                }
        } else {
                if (at->at_probe == ATA_PROBE_FAILED) {
                        at->at_probe = ATA_PROBE_NEED_HARD_RESET;
                        at->at_features |= ATA_PORT_F_RESCAN;
                        kprintf("%s: HOTPLUG (PM) - Device inserted\n",
                                ATANAME(ap, at));
                }
        }
}

/*
 * Read a PM register
 */
int
ahci_pm_read(struct ahci_port *ap, int target, int which, u_int32_t *datap)
{
        struct ata_xfer *xa;
        int error;

        xa = ahci_ata_get_xfer(ap, &ap->ap_ata[15]);

        xa->fis->type = ATA_FIS_TYPE_H2D;
        xa->fis->flags = ATA_H2D_FLAGS_CMD | 15;
        xa->fis->command = ATA_C_READ_PM;
        xa->fis->features = which;
        xa->fis->device = target | ATA_H2D_DEVICE_LBA;
        xa->fis->control = ATA_FIS_CONTROL_4BIT;

        xa->complete = ahci_pm_dummy_done;
        xa->datalen = 0;
        xa->flags = ATA_F_POLL | ATA_F_AUTOSENSE;
        xa->timeout = 1000;

        if (ahci_ata_cmd(xa) == ATA_S_COMPLETE) {
                *datap = xa->rfis.sector_count | (xa->rfis.lba_low << 8) |
                       (xa->rfis.lba_mid << 16) | (xa->rfis.lba_high << 24);
                error = 0;
        } else {
                kprintf("%s.%d pm_read SCA[%d] failed\n",
                        PORTNAME(ap), target, which);
                *datap = 0;
                error = EIO;
        }
        ahci_ata_put_xfer(xa);
        return (error);
}

/*
 * Write a PM register
 */
int
ahci_pm_write(struct ahci_port *ap, int target, int which, u_int32_t data)
{
        struct ata_xfer *xa;
        int error;

        xa = ahci_ata_get_xfer(ap, &ap->ap_ata[15]);

        xa->fis->type = ATA_FIS_TYPE_H2D;
        xa->fis->flags = ATA_H2D_FLAGS_CMD | 15;
        xa->fis->command = ATA_C_WRITE_PM;
        xa->fis->features = which;
        xa->fis->device = target | ATA_H2D_DEVICE_LBA;
        xa->fis->sector_count = (u_int8_t)data;
        xa->fis->lba_low = (u_int8_t)(data >> 8);
        xa->fis->lba_mid = (u_int8_t)(data >> 16);
        xa->fis->lba_high = (u_int8_t)(data >> 24);
        xa->fis->control = ATA_FIS_CONTROL_4BIT;

        xa->complete = ahci_pm_dummy_done;
        xa->datalen = 0;
        xa->flags = ATA_F_POLL;
        xa->timeout = 1000;

        if (ahci_ata_cmd(xa) == ATA_S_COMPLETE)
                error = 0;
        else
                error = EIO;
        ahci_ata_put_xfer(xa);
        return(error);
}

/*
 * Dummy done callback for xa.
 */
static void
ahci_pm_dummy_done(struct ata_xfer *xa)
{
}