device_fsm.c

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/*
 * finite state machine for device handling
 *
 *    Copyright IBM Corp. 2002, 2008
 *    Author(s): Cornelia Huck ([email protected])
 *       Martin Schwidefsky ([email protected])
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/string.h>

#include <asm/ccwdev.h>
#include <asm/cio.h>
#include <asm/chpid.h>

#include "cio.h"
#include "cio_debug.h"
#include "css.h"
#include "device.h"
#include "chsc.h"
#include "ioasm.h"
#include "chp.h"

static int timeout_log_enabled;

static int __init ccw_timeout_log_setup(char *unused)
{
    timeout_log_enabled = 1;
    return 1;
}

__setup("ccw_timeout_log", ccw_timeout_log_setup);

static void ccw_timeout_log(struct ccw_device *cdev)
{
    struct schib schib;
    struct subchannel *sch;
    struct io_subchannel_private *private;
    union orb *orb;
    int cc;

    sch = to_subchannel(cdev->dev.parent);
    private = to_io_private(sch);
    orb = &private->orb;
    cc = stsch_err(sch->schid, &schib);

    printk(KERN_WARNING "cio: ccw device timeout occurred at %llx, "
           "device information:\n", get_clock());
    printk(KERN_WARNING "cio: orb:\n");
    print_hex_dump(KERN_WARNING, "cio:  ", DUMP_PREFIX_NONE, 16, 1,
               orb, sizeof(*orb), 0);
    printk(KERN_WARNING "cio: ccw device bus id: %s\n",
           dev_name(&cdev->dev));
    printk(KERN_WARNING "cio: subchannel bus id: %s\n",
           dev_name(&sch->dev));
    printk(KERN_WARNING "cio: subchannel lpm: %02x, opm: %02x, "
           "vpm: %02x\n", sch->lpm, sch->opm, sch->vpm);

    if (orb->tm.b) {
        printk(KERN_WARNING "cio: orb indicates transport mode\n");
        printk(KERN_WARNING "cio: last tcw:\n");
        print_hex_dump(KERN_WARNING, "cio:  ", DUMP_PREFIX_NONE, 16, 1,
                   (void *)(addr_t)orb->tm.tcw,
                   sizeof(struct tcw), 0);
    } else {
        printk(KERN_WARNING "cio: orb indicates command mode\n");
        if ((void *)(addr_t)orb->cmd.cpa == &private->sense_ccw ||
            (void *)(addr_t)orb->cmd.cpa == cdev->private->iccws)
            printk(KERN_WARNING "cio: last channel program "
                   "(intern):\n");
        else
            printk(KERN_WARNING "cio: last channel program:\n");

        print_hex_dump(KERN_WARNING, "cio:  ", DUMP_PREFIX_NONE, 16, 1,
                   (void *)(addr_t)orb->cmd.cpa,
                   sizeof(struct ccw1), 0);
    }
    printk(KERN_WARNING "cio: ccw device state: %d\n",
           cdev->private->state);
    printk(KERN_WARNING "cio: store subchannel returned: cc=%d\n", cc);
    printk(KERN_WARNING "cio: schib:\n");
    print_hex_dump(KERN_WARNING, "cio:  ", DUMP_PREFIX_NONE, 16, 1,
               &schib, sizeof(schib), 0);
    printk(KERN_WARNING "cio: ccw device flags:\n");
    print_hex_dump(KERN_WARNING, "cio:  ", DUMP_PREFIX_NONE, 16, 1,
               &cdev->private->flags, sizeof(cdev->private->flags), 0);
}

/*
 * Timeout function. It just triggers a DEV_EVENT_TIMEOUT.
 */
static void
ccw_device_timeout(unsigned long data)
{
    struct ccw_device *cdev;

    cdev = (struct ccw_device *) data;
    spin_lock_irq(cdev->ccwlock);
    if (timeout_log_enabled)
        ccw_timeout_log(cdev);
    dev_fsm_event(cdev, DEV_EVENT_TIMEOUT);
    spin_unlock_irq(cdev->ccwlock);
}

/*
 * Set timeout
 */
void
ccw_device_set_timeout(struct ccw_device *cdev, int expires)
{
    if (expires == 0) {
        del_timer(&cdev->private->timer);
        return;
    }
    if (timer_pending(&cdev->private->timer)) {
        if (mod_timer(&cdev->private->timer, jiffies + expires))
            return;
    }
    cdev->private->timer.function = ccw_device_timeout;
    cdev->private->timer.data = (unsigned long) cdev;
    cdev->private->timer.expires = jiffies + expires;
    add_timer(&cdev->private->timer);
}

/*
 * Cancel running i/o. This is called repeatedly since halt/clear are
 * asynchronous operations. We do one try with cio_cancel, two tries
 * with cio_halt, 255 tries with cio_clear. If everythings fails panic.
 * Returns 0 if device now idle, -ENODEV for device not operational and
 * -EBUSY if an interrupt is expected (either from halt/clear or from a
 * status pending).
 */
int
ccw_device_cancel_halt_clear(struct ccw_device *cdev)
{
    struct subchannel *sch;
    int ret;

    sch = to_subchannel(cdev->dev.parent);
    if (cio_update_schib(sch))
        return -ENODEV; 
    if (!sch->schib.pmcw.ena)
        /* Not operational -> done. */
        return 0;
    /* Stage 1: cancel io. */
    if (!(scsw_actl(&sch->schib.scsw) & SCSW_ACTL_HALT_PEND) &&
        !(scsw_actl(&sch->schib.scsw) & SCSW_ACTL_CLEAR_PEND)) {
        if (!scsw_is_tm(&sch->schib.scsw)) {
            ret = cio_cancel(sch);
            if (ret != -EINVAL)
                return ret;
        }
        /* cancel io unsuccessful or not applicable (transport mode).
         * Continue with asynchronous instructions. */
        cdev->private->iretry = 3;  /* 3 halt retries. */
    }
    if (!(scsw_actl(&sch->schib.scsw) & SCSW_ACTL_CLEAR_PEND)) {
        /* Stage 2: halt io. */
        if (cdev->private->iretry) {
            cdev->private->iretry--;
            ret = cio_halt(sch);
            if (ret != -EBUSY)
                return (ret == 0) ? -EBUSY : ret;
        }
        /* halt io unsuccessful. */
        cdev->private->iretry = 255;    /* 255 clear retries. */
    }
    /* Stage 3: clear io. */
    if (cdev->private->iretry) {
        cdev->private->iretry--;
        ret = cio_clear (sch);
        return (ret == 0) ? -EBUSY : ret;
    }
    /* Function was unsuccessful */
    CIO_MSG_EVENT(0, "0.%x.%04x: could not stop I/O\n",
              cdev->private->dev_id.ssid, cdev->private->dev_id.devno);
    return -EIO;
}

void ccw_device_update_sense_data(struct ccw_device *cdev)
{
    memset(&cdev->id, 0, sizeof(cdev->id));
    cdev->id.cu_type   = cdev->private->senseid.cu_type;
    cdev->id.cu_model  = cdev->private->senseid.cu_model;
    cdev->id.dev_type  = cdev->private->senseid.dev_type;
    cdev->id.dev_model = cdev->private->senseid.dev_model;
}

int ccw_device_test_sense_data(struct ccw_device *cdev)
{
    return cdev->id.cu_type == cdev->private->senseid.cu_type &&
        cdev->id.cu_model == cdev->private->senseid.cu_model &&
        cdev->id.dev_type == cdev->private->senseid.dev_type &&
        cdev->id.dev_model == cdev->private->senseid.dev_model;
}

/*
 * The machine won't give us any notification by machine check if a chpid has
 * been varied online on the SE so we have to find out by magic (i. e. driving
 * the channel subsystem to device selection and updating our path masks).
 */
static void
__recover_lost_chpids(struct subchannel *sch, int old_lpm)
{
    int mask, i;
    struct chp_id chpid;

    chp_id_init(&chpid);
    for (i = 0; i<8; i++) {
        mask = 0x80 >> i;
        if (!(sch->lpm & mask))
            continue;
        if (old_lpm & mask)
            continue;
        chpid.id = sch->schib.pmcw.chpid[i];
        if (!chp_is_registered(chpid))
            css_schedule_eval_all();
    }
}

/*
 * Stop device recognition.
 */
static void
ccw_device_recog_done(struct ccw_device *cdev, int state)
{
    struct subchannel *sch;
    int old_lpm;

    sch = to_subchannel(cdev->dev.parent);

    if (cio_disable_subchannel(sch))
        state = DEV_STATE_NOT_OPER;
    /*
     * Now that we tried recognition, we have performed device selection
     * through ssch() and the path information is up to date.
     */
    old_lpm = sch->lpm;

    /* Check since device may again have become not operational. */
    if (cio_update_schib(sch))
        state = DEV_STATE_NOT_OPER;
    else
        sch->lpm = sch->schib.pmcw.pam & sch->opm;

    if (cdev->private->state == DEV_STATE_DISCONNECTED_SENSE_ID)
        /* Force reprobe on all chpids. */
        old_lpm = 0;
    if (sch->lpm != old_lpm)
        __recover_lost_chpids(sch, old_lpm);
    if (cdev->private->state == DEV_STATE_DISCONNECTED_SENSE_ID &&
        (state == DEV_STATE_NOT_OPER || state == DEV_STATE_BOXED)) {
        cdev->private->flags.recog_done = 1;
        cdev->private->state = DEV_STATE_DISCONNECTED;
        wake_up(&cdev->private->wait_q);
        return;
    }
    if (cdev->private->flags.resuming) {
        cdev->private->state = state;
        cdev->private->flags.recog_done = 1;
        wake_up(&cdev->private->wait_q);
        return;
    }
    switch (state) {
    case DEV_STATE_NOT_OPER:
        break;
    case DEV_STATE_OFFLINE:
        if (!cdev->online) {
            ccw_device_update_sense_data(cdev);
            break;
        }
        cdev->private->state = DEV_STATE_OFFLINE;
        cdev->private->flags.recog_done = 1;
        if (ccw_device_test_sense_data(cdev)) {
            cdev->private->flags.donotify = 1;
            ccw_device_online(cdev);
            wake_up(&cdev->private->wait_q);
        } else {
            ccw_device_update_sense_data(cdev);
            ccw_device_sched_todo(cdev, CDEV_TODO_REBIND);
        }
        return;
    case DEV_STATE_BOXED:
        if (cdev->id.cu_type != 0) { /* device was recognized before */
            cdev->private->flags.recog_done = 1;
            cdev->private->state = DEV_STATE_BOXED;
            wake_up(&cdev->private->wait_q);
            return;
        }
        break;
    }
    cdev->private->state = state;
    io_subchannel_recog_done(cdev);
    wake_up(&cdev->private->wait_q);
}

/*
 * Function called from device_id.c after sense id has completed.
 */
void
ccw_device_sense_id_done(struct ccw_device *cdev, int err)
{
    switch (err) {
    case 0:
        ccw_device_recog_done(cdev, DEV_STATE_OFFLINE);
        break;
    case -ETIME:        /* Sense id stopped by timeout. */
        ccw_device_recog_done(cdev, DEV_STATE_BOXED);
        break;
    default:
        ccw_device_recog_done(cdev, DEV_STATE_NOT_OPER);
        break;
    }
}

int ccw_device_notify(struct ccw_device *cdev, int event)
{
    int ret = -EINVAL;

    if (!cdev->drv)
        goto out;
    if (!cdev->online)
        goto out;
    CIO_MSG_EVENT(2, "notify called for 0.%x.%04x, event=%d\n",
              cdev->private->dev_id.ssid, cdev->private->dev_id.devno,
              event);
    if (!cdev->drv->notify) {
        ret = -EOPNOTSUPP;
        goto out;
    }
    if (cdev->drv->notify(cdev, event))
        ret = NOTIFY_OK;
    else
        ret = NOTIFY_BAD;
out:
    return ret;
}

static void ccw_device_oper_notify(struct ccw_device *cdev)
{
    struct subchannel *sch = to_subchannel(cdev->dev.parent);

    if (ccw_device_notify(cdev, CIO_OPER) == NOTIFY_OK) {
        /* Reenable channel measurements, if needed. */
        ccw_device_sched_todo(cdev, CDEV_TODO_ENABLE_CMF);
        /* Save indication for new paths. */
        cdev->private->path_new_mask = sch->vpm;
        return;
    }
    /* Driver doesn't want device back. */
    ccw_device_set_notoper(cdev);
    ccw_device_sched_todo(cdev, CDEV_TODO_REBIND);
}

/*
 * Finished with online/offline processing.
 */
static void
ccw_device_done(struct ccw_device *cdev, int state)
{
    struct subchannel *sch;

    sch = to_subchannel(cdev->dev.parent);

    ccw_device_set_timeout(cdev, 0);

    if (state != DEV_STATE_ONLINE)
        cio_disable_subchannel(sch);

    /* Reset device status. */
    memset(&cdev->private->irb, 0, sizeof(struct irb));

    cdev->private->state = state;

    switch (state) {
    case DEV_STATE_BOXED:
        CIO_MSG_EVENT(0, "Boxed device %04x on subchannel %04x\n",
                  cdev->private->dev_id.devno, sch->schid.sch_no);
        if (cdev->online &&
            ccw_device_notify(cdev, CIO_BOXED) != NOTIFY_OK)
            ccw_device_sched_todo(cdev, CDEV_TODO_UNREG);
        cdev->private->flags.donotify = 0;
        break;
    case DEV_STATE_NOT_OPER:
        CIO_MSG_EVENT(0, "Device %04x gone on subchannel %04x\n",
                  cdev->private->dev_id.devno, sch->schid.sch_no);
        if (ccw_device_notify(cdev, CIO_GONE) != NOTIFY_OK)
            ccw_device_sched_todo(cdev, CDEV_TODO_UNREG);
        else
            ccw_device_set_disconnected(cdev);
        cdev->private->flags.donotify = 0;
        break;
    case DEV_STATE_DISCONNECTED:
        CIO_MSG_EVENT(0, "Disconnected device %04x on subchannel "
                  "%04x\n", cdev->private->dev_id.devno,
                  sch->schid.sch_no);
        if (ccw_device_notify(cdev, CIO_NO_PATH) != NOTIFY_OK) {
            cdev->private->state = DEV_STATE_NOT_OPER;
            ccw_device_sched_todo(cdev, CDEV_TODO_UNREG);
        } else
            ccw_device_set_disconnected(cdev);
        cdev->private->flags.donotify = 0;
        break;
    default:
        break;
    }

    if (cdev->private->flags.donotify) {
        cdev->private->flags.donotify = 0;
        ccw_device_oper_notify(cdev);
    }
    wake_up(&cdev->private->wait_q);
}

/*
 * Start device recognition.
 */
void ccw_device_recognition(struct ccw_device *cdev)
{
    struct subchannel *sch = to_subchannel(cdev->dev.parent);

    /*
     * We used to start here with a sense pgid to find out whether a device
     * is locked by someone else. Unfortunately, the sense pgid command
     * code has other meanings on devices predating the path grouping
     * algorithm, so we start with sense id and box the device after an
     * timeout (or if sense pgid during path verification detects the device
     * is locked, as may happen on newer devices).
     */
    cdev->private->flags.recog_done = 0;
    cdev->private->state = DEV_STATE_SENSE_ID;
    if (cio_enable_subchannel(sch, (u32) (addr_t) sch)) {
        ccw_device_recog_done(cdev, DEV_STATE_NOT_OPER);
        return;
    }
    ccw_device_sense_id_start(cdev);
}

/*
 * Handle events for states that use the ccw request infrastructure.
 */
static void ccw_device_request_event(struct ccw_device *cdev, enum dev_event e)
{
    switch (e) {
    case DEV_EVENT_NOTOPER:
        ccw_request_notoper(cdev);
        break;
    case DEV_EVENT_INTERRUPT:
        ccw_request_handler(cdev);
        break;
    case DEV_EVENT_TIMEOUT:
        ccw_request_timeout(cdev);
        break;
    default:
        break;
    }
}

static void ccw_device_report_path_events(struct ccw_device *cdev)
{
    struct subchannel *sch = to_subchannel(cdev->dev.parent);
    int path_event[8];
    int chp, mask;

    for (chp = 0, mask = 0x80; chp < 8; chp++, mask >>= 1) {
        path_event[chp] = PE_NONE;
        if (mask & cdev->private->path_gone_mask & ~(sch->vpm))
            path_event[chp] |= PE_PATH_GONE;
        if (mask & cdev->private->path_new_mask & sch->vpm)
            path_event[chp] |= PE_PATH_AVAILABLE;
        if (mask & cdev->private->pgid_reset_mask & sch->vpm)
            path_event[chp] |= PE_PATHGROUP_ESTABLISHED;
    }
    if (cdev->online && cdev->drv->path_event)
        cdev->drv->path_event(cdev, path_event);
}

static void ccw_device_reset_path_events(struct ccw_device *cdev)
{
    cdev->private->path_gone_mask = 0;
    cdev->private->path_new_mask = 0;
    cdev->private->pgid_reset_mask = 0;
}

static void create_fake_irb(struct irb *irb, int type)
{
    memset(irb, 0, sizeof(*irb));
    if (type == FAKE_CMD_IRB) {
        struct cmd_scsw *scsw = &irb->scsw.cmd;
        scsw->cc = 1;
        scsw->fctl = SCSW_FCTL_START_FUNC;
        scsw->actl = SCSW_ACTL_START_PEND;
        scsw->stctl = SCSW_STCTL_STATUS_PEND;
    } else if (type == FAKE_TM_IRB) {
        struct tm_scsw *scsw = &irb->scsw.tm;
        scsw->x = 1;
        scsw->cc = 1;
        scsw->fctl = SCSW_FCTL_START_FUNC;
        scsw->actl = SCSW_ACTL_START_PEND;
        scsw->stctl = SCSW_STCTL_STATUS_PEND;
    }
}

void ccw_device_verify_done(struct ccw_device *cdev, int err)
{
    struct subchannel *sch;

    sch = to_subchannel(cdev->dev.parent);
    /* Update schib - pom may have changed. */
    if (cio_update_schib(sch)) {
        err = -ENODEV;
        goto callback;
    }
    /* Update lpm with verified path mask. */
    sch->lpm = sch->vpm;
    /* Repeat path verification? */
    if (cdev->private->flags.doverify) {
        ccw_device_verify_start(cdev);
        return;
    }
callback:
    switch (err) {
    case 0:
        ccw_device_done(cdev, DEV_STATE_ONLINE);
        /* Deliver fake irb to device driver, if needed. */
        if (cdev->private->flags.fake_irb) {
            create_fake_irb(&cdev->private->irb,
                    cdev->private->flags.fake_irb);
            cdev->private->flags.fake_irb = 0;
            if (cdev->handler)
                cdev->handler(cdev, cdev->private->intparm,
                          &cdev->private->irb);
            memset(&cdev->private->irb, 0, sizeof(struct irb));
        }
        ccw_device_report_path_events(cdev);
        break;
    case -ETIME:
    case -EUSERS:
        /* Reset oper notify indication after verify error. */
        cdev->private->flags.donotify = 0;
        ccw_device_done(cdev, DEV_STATE_BOXED);
        break;
    case -EACCES:
        /* Reset oper notify indication after verify error. */
        cdev->private->flags.donotify = 0;
        ccw_device_done(cdev, DEV_STATE_DISCONNECTED);
        break;
    default:
        /* Reset oper notify indication after verify error. */
        cdev->private->flags.donotify = 0;
        ccw_device_done(cdev, DEV_STATE_NOT_OPER);
        break;
    }
    ccw_device_reset_path_events(cdev);
}

/*
 * Get device online.
 */
int
ccw_device_online(struct ccw_device *cdev)
{
    struct subchannel *sch;
    int ret;

    if ((cdev->private->state != DEV_STATE_OFFLINE) &&
        (cdev->private->state != DEV_STATE_BOXED))
        return -EINVAL;
    sch = to_subchannel(cdev->dev.parent);
    ret = cio_enable_subchannel(sch, (u32)(addr_t)sch);
    if (ret != 0) {
        /* Couldn't enable the subchannel for i/o. Sick device. */
        if (ret == -ENODEV)
            dev_fsm_event(cdev, DEV_EVENT_NOTOPER);
        return ret;
    }
    /* Start initial path verification. */
    cdev->private->state = DEV_STATE_VERIFY;
    ccw_device_verify_start(cdev);
    return 0;
}

void
ccw_device_disband_done(struct ccw_device *cdev, int err)
{
    switch (err) {
    case 0:
        ccw_device_done(cdev, DEV_STATE_OFFLINE);
        break;
    case -ETIME:
        ccw_device_done(cdev, DEV_STATE_BOXED);
        break;
    default:
        cdev->private->flags.donotify = 0;
        ccw_device_done(cdev, DEV_STATE_NOT_OPER);
        break;
    }
}

/*
 * Shutdown device.
 */
int
ccw_device_offline(struct ccw_device *cdev)
{
    struct subchannel *sch;

    /* Allow ccw_device_offline while disconnected. */
    if (cdev->private->state == DEV_STATE_DISCONNECTED ||
        cdev->private->state == DEV_STATE_NOT_OPER) {
        cdev->private->flags.donotify = 0;
        ccw_device_done(cdev, DEV_STATE_NOT_OPER);
        return 0;
    }
    if (cdev->private->state == DEV_STATE_BOXED) {
        ccw_device_done(cdev, DEV_STATE_BOXED);
        return 0;
    }
    if (ccw_device_is_orphan(cdev)) {
        ccw_device_done(cdev, DEV_STATE_OFFLINE);
        return 0;
    }
    sch = to_subchannel(cdev->dev.parent);
    if (cio_update_schib(sch))
        return -ENODEV;
    if (scsw_actl(&sch->schib.scsw) != 0)
        return -EBUSY;
    if (cdev->private->state != DEV_STATE_ONLINE)
        return -EINVAL;
    /* Are we doing path grouping? */
    if (!cdev->private->flags.pgroup) {
        /* No, set state offline immediately. */
        ccw_device_done(cdev, DEV_STATE_OFFLINE);
        return 0;
    }
    /* Start Set Path Group commands. */
    cdev->private->state = DEV_STATE_DISBAND_PGID;
    ccw_device_disband_start(cdev);
    return 0;
}

/*
 * Handle not operational event in non-special state.
 */
static void ccw_device_generic_notoper(struct ccw_device *cdev,
                       enum dev_event dev_event)
{
    if (ccw_device_notify(cdev, CIO_GONE) != NOTIFY_OK)
        ccw_device_sched_todo(cdev, CDEV_TODO_UNREG);
    else
        ccw_device_set_disconnected(cdev);
}

/*
 * Handle path verification event in offline state.
 */
static void ccw_device_offline_verify(struct ccw_device *cdev,
                      enum dev_event dev_event)
{
    struct subchannel *sch = to_subchannel(cdev->dev.parent);

    css_schedule_eval(sch->schid);
}

/*
 * Handle path verification event.
 */
static void
ccw_device_online_verify(struct ccw_device *cdev, enum dev_event dev_event)
{
    struct subchannel *sch;

    if (cdev->private->state == DEV_STATE_W4SENSE) {
        cdev->private->flags.doverify = 1;
        return;
    }
    sch = to_subchannel(cdev->dev.parent);
    /*
     * Since we might not just be coming from an interrupt from the
     * subchannel we have to update the schib.
     */
    if (cio_update_schib(sch)) {
        ccw_device_verify_done(cdev, -ENODEV);
        return;
    }

    if (scsw_actl(&sch->schib.scsw) != 0 ||
        (scsw_stctl(&sch->schib.scsw) & SCSW_STCTL_STATUS_PEND) ||
        (scsw_stctl(&cdev->private->irb.scsw) & SCSW_STCTL_STATUS_PEND)) {
        /*
         * No final status yet or final status not yet delivered
         * to the device driver. Can't do path verification now,
         * delay until final status was delivered.
         */
        cdev->private->flags.doverify = 1;
        return;
    }
    /* Device is idle, we can do the path verification. */
    cdev->private->state = DEV_STATE_VERIFY;
    ccw_device_verify_start(cdev);
}

/*
 * Handle path verification event in boxed state.
 */
static void ccw_device_boxed_verify(struct ccw_device *cdev,
                    enum dev_event dev_event)
{
    struct subchannel *sch = to_subchannel(cdev->dev.parent);

    if (cdev->online) {
        if (cio_enable_subchannel(sch, (u32) (addr_t) sch))
            ccw_device_done(cdev, DEV_STATE_NOT_OPER);
        else
            ccw_device_online_verify(cdev, dev_event);
    } else
        css_schedule_eval(sch->schid);
}

/*
 * Got an interrupt for a normal io (state online).
 */
static void
ccw_device_irq(struct ccw_device *cdev, enum dev_event dev_event)
{
    struct irb *irb;
    int is_cmd;

    irb = (struct irb *)&S390_lowcore.irb;
    is_cmd = !scsw_is_tm(&irb->scsw);
    /* Check for unsolicited interrupt. */
    if (!scsw_is_solicited(&irb->scsw)) {
        if (is_cmd && (irb->scsw.cmd.dstat & DEV_STAT_UNIT_CHECK) &&
            !irb->esw.esw0.erw.cons) {
            /* Unit check but no sense data. Need basic sense. */
            if (ccw_device_do_sense(cdev, irb) != 0)
                goto call_handler_unsol;
            memcpy(&cdev->private->irb, irb, sizeof(struct irb));
            cdev->private->state = DEV_STATE_W4SENSE;
            cdev->private->intparm = 0;
            return;
        }
call_handler_unsol:
        if (cdev->handler)
            cdev->handler (cdev, 0, irb);
        if (cdev->private->flags.doverify)
            ccw_device_online_verify(cdev, 0);
        return;
    }
    /* Accumulate status and find out if a basic sense is needed. */
    ccw_device_accumulate_irb(cdev, irb);
    if (is_cmd && cdev->private->flags.dosense) {
        if (ccw_device_do_sense(cdev, irb) == 0) {
            cdev->private->state = DEV_STATE_W4SENSE;
        }
        return;
    }
    /* Call the handler. */
    if (ccw_device_call_handler(cdev) && cdev->private->flags.doverify)
        /* Start delayed path verification. */
        ccw_device_online_verify(cdev, 0);
}

/*
 * Got an timeout in online state.
 */
static void
ccw_device_online_timeout(struct ccw_device *cdev, enum dev_event dev_event)
{
    int ret;

    ccw_device_set_timeout(cdev, 0);
    cdev->private->iretry = 255;
    ret = ccw_device_cancel_halt_clear(cdev);
    if (ret == -EBUSY) {
        ccw_device_set_timeout(cdev, 3*HZ);
        cdev->private->state = DEV_STATE_TIMEOUT_KILL;
        return;
    }
    if (ret)
        dev_fsm_event(cdev, DEV_EVENT_NOTOPER);
    else if (cdev->handler)
        cdev->handler(cdev, cdev->private->intparm,
                  ERR_PTR(-ETIMEDOUT));
}

/*
 * Got an interrupt for a basic sense.
 */
static void
ccw_device_w4sense(struct ccw_device *cdev, enum dev_event dev_event)
{
    struct irb *irb;

    irb = (struct irb *)&S390_lowcore.irb;
    /* Check for unsolicited interrupt. */
    if (scsw_stctl(&irb->scsw) ==
        (SCSW_STCTL_STATUS_PEND | SCSW_STCTL_ALERT_STATUS)) {
        if (scsw_cc(&irb->scsw) == 1)
            /* Basic sense hasn't started. Try again. */
            ccw_device_do_sense(cdev, irb);
        else {
            CIO_MSG_EVENT(0, "0.%x.%04x: unsolicited "
                      "interrupt during w4sense...\n",
                      cdev->private->dev_id.ssid,
                      cdev->private->dev_id.devno);
            if (cdev->handler)
                cdev->handler (cdev, 0, irb);
        }
        return;
    }
    /*
     * Check if a halt or clear has been issued in the meanwhile. If yes,
     * only deliver the halt/clear interrupt to the device driver as if it
     * had killed the original request.
     */
    if (scsw_fctl(&irb->scsw) &
        (SCSW_FCTL_CLEAR_FUNC | SCSW_FCTL_HALT_FUNC)) {
        cdev->private->flags.dosense = 0;
        memset(&cdev->private->irb, 0, sizeof(struct irb));
        ccw_device_accumulate_irb(cdev, irb);
        goto call_handler;
    }
    /* Add basic sense info to irb. */
    ccw_device_accumulate_basic_sense(cdev, irb);
    if (cdev->private->flags.dosense) {
        /* Another basic sense is needed. */
        ccw_device_do_sense(cdev, irb);
        return;
    }
call_handler:
    cdev->private->state = DEV_STATE_ONLINE;
    /* In case sensing interfered with setting the device online */
    wake_up(&cdev->private->wait_q);
    /* Call the handler. */
    if (ccw_device_call_handler(cdev) && cdev->private->flags.doverify)
        /* Start delayed path verification. */
        ccw_device_online_verify(cdev, 0);
}

static void
ccw_device_killing_irq(struct ccw_device *cdev, enum dev_event dev_event)
{
    ccw_device_set_timeout(cdev, 0);
    /* Start delayed path verification. */
    ccw_device_online_verify(cdev, 0);
    /* OK, i/o is dead now. Call interrupt handler. */
    if (cdev->handler)
        cdev->handler(cdev, cdev->private->intparm,
                  ERR_PTR(-EIO));
}

static void
ccw_device_killing_timeout(struct ccw_device *cdev, enum dev_event dev_event)
{
    int ret;

    ret = ccw_device_cancel_halt_clear(cdev);
    if (ret == -EBUSY) {
        ccw_device_set_timeout(cdev, 3*HZ);
        return;
    }
    /* Start delayed path verification. */
    ccw_device_online_verify(cdev, 0);
    if (cdev->handler)
        cdev->handler(cdev, cdev->private->intparm,
                  ERR_PTR(-EIO));
}

void ccw_device_kill_io(struct ccw_device *cdev)
{
    int ret;

    cdev->private->iretry = 255;
    ret = ccw_device_cancel_halt_clear(cdev);
    if (ret == -EBUSY) {
        ccw_device_set_timeout(cdev, 3*HZ);
        cdev->private->state = DEV_STATE_TIMEOUT_KILL;
        return;
    }
    /* Start delayed path verification. */
    ccw_device_online_verify(cdev, 0);
    if (cdev->handler)
        cdev->handler(cdev, cdev->private->intparm,
                  ERR_PTR(-EIO));
}

static void
ccw_device_delay_verify(struct ccw_device *cdev, enum dev_event dev_event)
{
    /* Start verification after current task finished. */
    cdev->private->flags.doverify = 1;
}

static void
ccw_device_start_id(struct ccw_device *cdev, enum dev_event dev_event)
{
    struct subchannel *sch;

    sch = to_subchannel(cdev->dev.parent);
    if (cio_enable_subchannel(sch, (u32)(addr_t)sch) != 0)
        /* Couldn't enable the subchannel for i/o. Sick device. */
        return;
    cdev->private->state = DEV_STATE_DISCONNECTED_SENSE_ID;
    ccw_device_sense_id_start(cdev);
}

void ccw_device_trigger_reprobe(struct ccw_device *cdev)
{
    struct subchannel *sch;

    if (cdev->private->state != DEV_STATE_DISCONNECTED)
        return;

    sch = to_subchannel(cdev->dev.parent);
    /* Update some values. */
    if (cio_update_schib(sch))
        return;
    /*
     * The pim, pam, pom values may not be accurate, but they are the best
     * we have before performing device selection :/
     */
    sch->lpm = sch->schib.pmcw.pam & sch->opm;
    /*
     * Use the initial configuration since we can't be shure that the old
     * paths are valid.
     */
    io_subchannel_init_config(sch);
    if (cio_commit_config(sch))
        return;

    /* We should also udate ssd info, but this has to wait. */
    /* Check if this is another device which appeared on the same sch. */
    if (sch->schib.pmcw.dev != cdev->private->dev_id.devno)
        css_schedule_eval(sch->schid);
    else
        ccw_device_start_id(cdev, 0);
}

static void ccw_device_disabled_irq(struct ccw_device *cdev,
                    enum dev_event dev_event)
{
    struct subchannel *sch;

    sch = to_subchannel(cdev->dev.parent);
    /*
     * An interrupt in a disabled state means a previous disable was not
     * successful - should not happen, but we try to disable again.
     */
    cio_disable_subchannel(sch);
}

static void
ccw_device_change_cmfstate(struct ccw_device *cdev, enum dev_event dev_event)
{
    retry_set_schib(cdev);
    cdev->private->state = DEV_STATE_ONLINE;
    dev_fsm_event(cdev, dev_event);
}

static void ccw_device_update_cmfblock(struct ccw_device *cdev,
                       enum dev_event dev_event)
{
    cmf_retry_copy_block(cdev);
    cdev->private->state = DEV_STATE_ONLINE;
    dev_fsm_event(cdev, dev_event);
}

static void
ccw_device_quiesce_done(struct ccw_device *cdev, enum dev_event dev_event)
{
    ccw_device_set_timeout(cdev, 0);
    cdev->private->state = DEV_STATE_NOT_OPER;
    wake_up(&cdev->private->wait_q);
}

static void
ccw_device_quiesce_timeout(struct ccw_device *cdev, enum dev_event dev_event)
{
    int ret;

    ret = ccw_device_cancel_halt_clear(cdev);
    if (ret == -EBUSY) {
        ccw_device_set_timeout(cdev, HZ/10);
    } else {
        cdev->private->state = DEV_STATE_NOT_OPER;
        wake_up(&cdev->private->wait_q);
    }
}

/*
 * No operation action. This is used e.g. to ignore a timeout event in
 * state offline.
 */
static void
ccw_device_nop(struct ccw_device *cdev, enum dev_event dev_event)
{
}

/*
 * device statemachine
 */
fsm_func_t *dev_jumptable[NR_DEV_STATES][NR_DEV_EVENTS] = {
    [DEV_STATE_NOT_OPER] = {
        [DEV_EVENT_NOTOPER] = ccw_device_nop,
        [DEV_EVENT_INTERRUPT]   = ccw_device_disabled_irq,
        [DEV_EVENT_TIMEOUT] = ccw_device_nop,
        [DEV_EVENT_VERIFY]  = ccw_device_nop,
    },
    [DEV_STATE_SENSE_PGID] = {
        [DEV_EVENT_NOTOPER] = ccw_device_request_event,
        [DEV_EVENT_INTERRUPT]   = ccw_device_request_event,
        [DEV_EVENT_TIMEOUT] = ccw_device_request_event,
        [DEV_EVENT_VERIFY]  = ccw_device_nop,
    },
    [DEV_STATE_SENSE_ID] = {
        [DEV_EVENT_NOTOPER] = ccw_device_request_event,
        [DEV_EVENT_INTERRUPT]   = ccw_device_request_event,
        [DEV_EVENT_TIMEOUT] = ccw_device_request_event,
        [DEV_EVENT_VERIFY]  = ccw_device_nop,
    },
    [DEV_STATE_OFFLINE] = {
        [DEV_EVENT_NOTOPER] = ccw_device_generic_notoper,
        [DEV_EVENT_INTERRUPT]   = ccw_device_disabled_irq,
        [DEV_EVENT_TIMEOUT] = ccw_device_nop,
        [DEV_EVENT_VERIFY]  = ccw_device_offline_verify,
    },
    [DEV_STATE_VERIFY] = {
        [DEV_EVENT_NOTOPER] = ccw_device_request_event,
        [DEV_EVENT_INTERRUPT]   = ccw_device_request_event,
        [DEV_EVENT_TIMEOUT] = ccw_device_request_event,
        [DEV_EVENT_VERIFY]  = ccw_device_delay_verify,
    },
    [DEV_STATE_ONLINE] = {
        [DEV_EVENT_NOTOPER] = ccw_device_generic_notoper,
        [DEV_EVENT_INTERRUPT]   = ccw_device_irq,
        [DEV_EVENT_TIMEOUT] = ccw_device_online_timeout,
        [DEV_EVENT_VERIFY]  = ccw_device_online_verify,
    },
    [DEV_STATE_W4SENSE] = {
        [DEV_EVENT_NOTOPER] = ccw_device_generic_notoper,
        [DEV_EVENT_INTERRUPT]   = ccw_device_w4sense,
        [DEV_EVENT_TIMEOUT] = ccw_device_nop,
        [DEV_EVENT_VERIFY]  = ccw_device_online_verify,
    },
    [DEV_STATE_DISBAND_PGID] = {
        [DEV_EVENT_NOTOPER] = ccw_device_request_event,
        [DEV_EVENT_INTERRUPT]   = ccw_device_request_event,
        [DEV_EVENT_TIMEOUT] = ccw_device_request_event,
        [DEV_EVENT_VERIFY]  = ccw_device_nop,
    },
    [DEV_STATE_BOXED] = {
        [DEV_EVENT_NOTOPER] = ccw_device_generic_notoper,
        [DEV_EVENT_INTERRUPT]   = ccw_device_nop,
        [DEV_EVENT_TIMEOUT] = ccw_device_nop,
        [DEV_EVENT_VERIFY]  = ccw_device_boxed_verify,
    },
    /* states to wait for i/o completion before doing something */
    [DEV_STATE_TIMEOUT_KILL] = {
        [DEV_EVENT_NOTOPER] = ccw_device_generic_notoper,
        [DEV_EVENT_INTERRUPT]   = ccw_device_killing_irq,
        [DEV_EVENT_TIMEOUT] = ccw_device_killing_timeout,
        [DEV_EVENT_VERIFY]  = ccw_device_nop, //FIXME
    },
    [DEV_STATE_QUIESCE] = {
        [DEV_EVENT_NOTOPER] = ccw_device_quiesce_done,
        [DEV_EVENT_INTERRUPT]   = ccw_device_quiesce_done,
        [DEV_EVENT_TIMEOUT] = ccw_device_quiesce_timeout,
        [DEV_EVENT_VERIFY]  = ccw_device_nop,
    },
    /* special states for devices gone not operational */
    [DEV_STATE_DISCONNECTED] = {
        [DEV_EVENT_NOTOPER] = ccw_device_nop,
        [DEV_EVENT_INTERRUPT]   = ccw_device_start_id,
        [DEV_EVENT_TIMEOUT] = ccw_device_nop,
        [DEV_EVENT_VERIFY]  = ccw_device_start_id,
    },
    [DEV_STATE_DISCONNECTED_SENSE_ID] = {
        [DEV_EVENT_NOTOPER] = ccw_device_request_event,
        [DEV_EVENT_INTERRUPT]   = ccw_device_request_event,
        [DEV_EVENT_TIMEOUT] = ccw_device_request_event,
        [DEV_EVENT_VERIFY]  = ccw_device_nop,
    },
    [DEV_STATE_CMFCHANGE] = {
        [DEV_EVENT_NOTOPER] = ccw_device_change_cmfstate,
        [DEV_EVENT_INTERRUPT]   = ccw_device_change_cmfstate,
        [DEV_EVENT_TIMEOUT] = ccw_device_change_cmfstate,
        [DEV_EVENT_VERIFY]  = ccw_device_change_cmfstate,
    },
    [DEV_STATE_CMFUPDATE] = {
        [DEV_EVENT_NOTOPER] = ccw_device_update_cmfblock,
        [DEV_EVENT_INTERRUPT]   = ccw_device_update_cmfblock,
        [DEV_EVENT_TIMEOUT] = ccw_device_update_cmfblock,
        [DEV_EVENT_VERIFY]  = ccw_device_update_cmfblock,
    },
    [DEV_STATE_STEAL_LOCK] = {
        [DEV_EVENT_NOTOPER] = ccw_device_request_event,
        [DEV_EVENT_INTERRUPT]   = ccw_device_request_event,
        [DEV_EVENT_TIMEOUT] = ccw_device_request_event,
        [DEV_EVENT_VERIFY]  = ccw_device_nop,
    },
};

EXPORT_SYMBOL_GPL(ccw_device_set_timeout);