Fix race between proc_get_inode() and remove_proc_entry()

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / s390 / cio / device_fsm.c

/*
 * drivers/s390/cio/device_fsm.c
 * finite state machine for device handling
 *
 *    Copyright (C) 2002 IBM Deutschland Entwicklung GmbH,
 *                       IBM Corporation
 *    Author(s): Cornelia Huck (cornelia.huck@de.ibm.com)
 *               Martin Schwidefsky (schwidefsky@de.ibm.com)
 */

#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"

int
device_is_online(struct subchannel *sch)
{
        struct ccw_device *cdev;

        if (!sch->dev.driver_data)
                return 0;
        cdev = sch->dev.driver_data;
        return (cdev->private->state == DEV_STATE_ONLINE);
}

int
device_is_disconnected(struct subchannel *sch)
{
        struct ccw_device *cdev;

        if (!sch->dev.driver_data)
                return 0;
        cdev = sch->dev.driver_data;
        return (cdev->private->state == DEV_STATE_DISCONNECTED ||
                cdev->private->state == DEV_STATE_DISCONNECTED_SENSE_ID);
}

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

        if (!sch->dev.driver_data)
                return;
        cdev = sch->dev.driver_data;
        ccw_device_set_timeout(cdev, 0);
        cdev->private->flags.fake_irb = 0;
        cdev->private->state = DEV_STATE_DISCONNECTED;
}

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

        cdev = sch->dev.driver_data;
        if (!cdev)
                return;
        cdev->private->flags.intretry = 1;
}

int device_trigger_verify(struct subchannel *sch)
{
        struct ccw_device *cdev;

        cdev = sch->dev.driver_data;
        if (!cdev || !cdev->online)
                return -EINVAL;
        dev_fsm_event(cdev, DEV_EVENT_VERIFY);
        return 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);
        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);
}

/* Kill any pending timers after machine check. */
void
device_kill_pending_timer(struct subchannel *sch)
{
        struct ccw_device *cdev;

        if (!sch->dev.driver_data)
                return;
        cdev = sch->dev.driver_data;
        ccw_device_set_timeout(cdev, 0);
}

/*
 * 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);
        ret = stsch(sch->schid, &sch->schib);
        if (ret || !sch->schib.pmcw.dnv)
                return -ENODEV; 
        if (!sch->schib.pmcw.ena)
                /* Not operational -> done. */
                return 0;
        /* Stage 1: cancel io. */
        if (!(sch->schib.scsw.actl & SCSW_ACTL_HALT_PEND) &&
            !(sch->schib.scsw.actl & SCSW_ACTL_CLEAR_PEND)) {
                ret = cio_cancel(sch);
                if (ret != -EINVAL)
                        return ret;
                /* cancel io unsuccessful. From now on it is asynchronous. */
                cdev->private->iretry = 3;      /* 3 halt retries. */
        }
        if (!(sch->schib.scsw.actl & 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;
        }
        panic("Can't stop i/o on subchannel.\n");
}

static int
ccw_device_handle_oper(struct ccw_device *cdev)
{
        struct subchannel *sch;

        sch = to_subchannel(cdev->dev.parent);
        cdev->private->flags.recog_done = 1;
        /*
         * Check if cu type and device type still match. If
         * not, it is certainly another device and we have to
         * de- and re-register.
         */
        if (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) {
                PREPARE_WORK(&cdev->private->kick_work,
                             ccw_device_do_unreg_rereg);
                queue_work(ccw_device_work, &cdev->private->kick_work);
                return 0;
        }
        cdev->private->flags.donotify = 1;
        return 1;
}

/*
 * 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 notify, old_lpm, same_dev;

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

        ccw_device_set_timeout(cdev, 0);
        cio_disable_subchannel(sch);
        /*
         * Now that we tried recognition, we have performed device selection
         * through ssch() and the path information is up to date.
         */
        old_lpm = sch->lpm;
        stsch(sch->schid, &sch->schib);
        sch->lpm = sch->schib.pmcw.pam & sch->opm;
        /* Check since device may again have become not operational. */
        if (!sch->schib.pmcw.dnv)
                state = DEV_STATE_NOT_OPER;
        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) {
                if (state == DEV_STATE_NOT_OPER) {
                        cdev->private->flags.recog_done = 1;
                        cdev->private->state = DEV_STATE_DISCONNECTED;
                        return;
                }
                /* Boxed devices don't need extra treatment. */
        }
        notify = 0;
        same_dev = 0; /* Keep the compiler quiet... */
        switch (state) {
        case DEV_STATE_NOT_OPER:
                CIO_DEBUG(KERN_WARNING, 2,
                          "SenseID : unknown device %04x on subchannel "
                          "0.%x.%04x\n", cdev->private->dev_id.devno,
                          sch->schid.ssid, sch->schid.sch_no);
                break;
        case DEV_STATE_OFFLINE:
                if (cdev->private->state == DEV_STATE_DISCONNECTED_SENSE_ID) {
                        same_dev = ccw_device_handle_oper(cdev);
                        notify = 1;
                }
                /* fill out sense information */
                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;
                if (notify) {
                        cdev->private->state = DEV_STATE_OFFLINE;
                        if (same_dev) {
                                /* Get device online again. */
                                ccw_device_online(cdev);
                                wake_up(&cdev->private->wait_q);
                        }
                        return;
                }
                /* Issue device info message. */
                CIO_DEBUG(KERN_INFO, 2, "SenseID : device 0.%x.%04x reports: "
                          "CU  Type/Mod = %04X/%02X, Dev Type/Mod = "
                          "%04X/%02X\n",
                          cdev->private->dev_id.ssid,
                          cdev->private->dev_id.devno,
                          cdev->id.cu_type, cdev->id.cu_model,
                          cdev->id.dev_type, cdev->id.dev_model);
                break;
        case DEV_STATE_BOXED:
                CIO_DEBUG(KERN_WARNING, 2,
                          "SenseID : boxed device %04x on subchannel "
                          "0.%x.%04x\n", cdev->private->dev_id.devno,
                          sch->schid.ssid, sch->schid.sch_no);
                break;
        }
        cdev->private->state = state;
        io_subchannel_recog_done(cdev);
        if (state != DEV_STATE_NOT_OPER)
                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;
        }
}

static void
ccw_device_oper_notify(struct work_struct *work)
{
        struct ccw_device_private *priv;
        struct ccw_device *cdev;
        struct subchannel *sch;
        int ret;
        unsigned long flags;

        priv = container_of(work, struct ccw_device_private, kick_work);
        cdev = priv->cdev;
        spin_lock_irqsave(cdev->ccwlock, flags);
        sch = to_subchannel(cdev->dev.parent);
        if (sch->driver && sch->driver->notify) {
                spin_unlock_irqrestore(cdev->ccwlock, flags);
                ret = sch->driver->notify(&sch->dev, CIO_OPER);
                spin_lock_irqsave(cdev->ccwlock, flags);
        } else
                ret = 0;
        if (ret) {
                /* Reenable channel measurements, if needed. */
                spin_unlock_irqrestore(cdev->ccwlock, flags);
                cmf_reenable(cdev);
                spin_lock_irqsave(cdev->ccwlock, flags);
                wake_up(&cdev->private->wait_q);
        }
        spin_unlock_irqrestore(cdev->ccwlock, flags);
        if (!ret)
                /* Driver doesn't want device back. */
                ccw_device_do_unreg_rereg(work);
}

/*
 * 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;


        if (state == DEV_STATE_BOXED)
                CIO_DEBUG(KERN_WARNING, 2,
                          "Boxed device %04x on subchannel %04x\n",
                          cdev->private->dev_id.devno, sch->schid.sch_no);

        if (cdev->private->flags.donotify) {
                cdev->private->flags.donotify = 0;
                PREPARE_WORK(&cdev->private->kick_work, ccw_device_oper_notify);
                queue_work(ccw_device_notify_work, &cdev->private->kick_work);
        }
        wake_up(&cdev->private->wait_q);

        if (css_init_done && state != DEV_STATE_ONLINE)
                put_device (&cdev->dev);
}

static int cmp_pgid(struct pgid *p1, struct pgid *p2)
{
        char *c1;
        char *c2;

        c1 = (char *)p1;
        c2 = (char *)p2;

        return memcmp(c1 + 1, c2 + 1, sizeof(struct pgid) - 1);
}

static void __ccw_device_get_common_pgid(struct ccw_device *cdev)
{
        int i;
        int last;

        last = 0;
        for (i = 0; i < 8; i++) {
                if (cdev->private->pgid[i].inf.ps.state1 == SNID_STATE1_RESET)
                        /* No PGID yet */
                        continue;
                if (cdev->private->pgid[last].inf.ps.state1 ==
                    SNID_STATE1_RESET) {
                        /* First non-zero PGID */
                        last = i;
                        continue;
                }
                if (cmp_pgid(&cdev->private->pgid[i],
                             &cdev->private->pgid[last]) == 0)
                        /* Non-conflicting PGIDs */
                        continue;

                /* PGID mismatch, can't pathgroup. */
                CIO_MSG_EVENT(0, "SNID - pgid mismatch for device "
                              "0.%x.%04x, can't pathgroup\n",
                              cdev->private->dev_id.ssid,
                              cdev->private->dev_id.devno);
                cdev->private->options.pgroup = 0;
                return;
        }
        if (cdev->private->pgid[last].inf.ps.state1 ==
            SNID_STATE1_RESET)
                /* No previous pgid found */
                memcpy(&cdev->private->pgid[0], &css[0]->global_pgid,
                       sizeof(struct pgid));
        else
                /* Use existing pgid */
                memcpy(&cdev->private->pgid[0], &cdev->private->pgid[last],
                       sizeof(struct pgid));
}

/*
 * Function called from device_pgid.c after sense path ground has completed.
 */
void
ccw_device_sense_pgid_done(struct ccw_device *cdev, int err)
{
        struct subchannel *sch;

        sch = to_subchannel(cdev->dev.parent);
        switch (err) {
        case -EOPNOTSUPP: /* path grouping not supported, use nop instead. */
                cdev->private->options.pgroup = 0;
                break;
        case 0: /* success */
        case -EACCES: /* partial success, some paths not operational */
                /* Check if all pgids are equal or 0. */
                __ccw_device_get_common_pgid(cdev);
                break;
        case -ETIME:            /* Sense path group id stopped by timeout. */
        case -EUSERS:           /* device is reserved for someone else. */
                ccw_device_done(cdev, DEV_STATE_BOXED);
                return;
        default:
                ccw_device_done(cdev, DEV_STATE_NOT_OPER);
                return;
        }
        /* Start Path Group verification. */
        cdev->private->state = DEV_STATE_VERIFY;
        cdev->private->flags.doverify = 0;
        ccw_device_verify_start(cdev);
}

/*
 * Start device recognition.
 */
int
ccw_device_recognition(struct ccw_device *cdev)
{
        struct subchannel *sch;
        int ret;

        if ((cdev->private->state != DEV_STATE_NOT_OPER) &&
            (cdev->private->state != DEV_STATE_BOXED))
                return -EINVAL;
        sch = to_subchannel(cdev->dev.parent);
        ret = cio_enable_subchannel(sch, sch->schib.pmcw.isc);
        if (ret != 0)
                /* Couldn't enable the subchannel for i/o. Sick device. */
                return ret;

        /* After 60s the device recognition is considered to have failed. */
        ccw_device_set_timeout(cdev, 60*HZ);

        /*
         * 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;
        ccw_device_sense_id_start(cdev);
        return 0;
}

/*
 * Handle timeout in device recognition.
 */
static void
ccw_device_recog_timeout(struct ccw_device *cdev, enum dev_event dev_event)
{
        int ret;

        ret = ccw_device_cancel_halt_clear(cdev);
        switch (ret) {
        case 0:
                ccw_device_recog_done(cdev, DEV_STATE_BOXED);
                break;
        case -ENODEV:
                ccw_device_recog_done(cdev, DEV_STATE_NOT_OPER);
                break;
        default:
                ccw_device_set_timeout(cdev, 3*HZ);
        }
}


static void
ccw_device_nopath_notify(struct work_struct *work)
{
        struct ccw_device_private *priv;
        struct ccw_device *cdev;
        struct subchannel *sch;
        int ret;
        unsigned long flags;

        priv = container_of(work, struct ccw_device_private, kick_work);
        cdev = priv->cdev;
        spin_lock_irqsave(cdev->ccwlock, flags);
        sch = to_subchannel(cdev->dev.parent);
        /* Extra sanity. */
        if (sch->lpm)
                goto out_unlock;
        if (sch->driver && sch->driver->notify) {
                spin_unlock_irqrestore(cdev->ccwlock, flags);
                ret = sch->driver->notify(&sch->dev, CIO_NO_PATH);
                spin_lock_irqsave(cdev->ccwlock, flags);
        } else
                ret = 0;
        if (!ret) {
                if (get_device(&sch->dev)) {
                        /* Driver doesn't want to keep device. */
                        cio_disable_subchannel(sch);
                        if (get_device(&cdev->dev)) {
                                PREPARE_WORK(&cdev->private->kick_work,
                                             ccw_device_call_sch_unregister);
                                queue_work(ccw_device_work,
                                           &cdev->private->kick_work);
                        } else
                                put_device(&sch->dev);
                }
        } else {
                cio_disable_subchannel(sch);
                ccw_device_set_timeout(cdev, 0);
                cdev->private->flags.fake_irb = 0;
                cdev->private->state = DEV_STATE_DISCONNECTED;
                wake_up(&cdev->private->wait_q);
        }
out_unlock:
        spin_unlock_irqrestore(cdev->ccwlock, flags);
}

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. */
        stsch(sch->schid, &sch->schib);
        /* Update lpm with verified path mask. */
        sch->lpm = sch->vpm;
        /* Repeat path verification? */
        if (cdev->private->flags.doverify) {
                cdev->private->flags.doverify = 0;
                ccw_device_verify_start(cdev);
                return;
        }
        switch (err) {
        case -EOPNOTSUPP: /* path grouping not supported, just set online. */
                cdev->private->options.pgroup = 0;
        case 0:
                ccw_device_done(cdev, DEV_STATE_ONLINE);
                /* Deliver fake irb to device driver, if needed. */
                if (cdev->private->flags.fake_irb) {
                        memset(&cdev->private->irb, 0, sizeof(struct irb));
                        cdev->private->irb.scsw.cc = 1;
                        cdev->private->irb.scsw.fctl = SCSW_FCTL_START_FUNC;
                        cdev->private->irb.scsw.actl = SCSW_ACTL_START_PEND;
                        cdev->private->irb.scsw.stctl = SCSW_STCTL_STATUS_PEND;
                        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));
                }
                break;
        case -ETIME:
                /* Reset oper notify indication after verify error. */
                cdev->private->flags.donotify = 0;
                ccw_device_done(cdev, DEV_STATE_BOXED);
                break;
        default:
                /* Reset oper notify indication after verify error. */
                cdev->private->flags.donotify = 0;
                if (cdev->online) {
                        PREPARE_WORK(&cdev->private->kick_work,
                                     ccw_device_nopath_notify);
                        queue_work(ccw_device_notify_work,
                                   &cdev->private->kick_work);
                } else
                        ccw_device_done(cdev, DEV_STATE_NOT_OPER);
                break;
        }
}

/*
 * 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);
        if (css_init_done && !get_device(&cdev->dev))
                return -ENODEV;
        ret = cio_enable_subchannel(sch, sch->schib.pmcw.isc);
        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;
        }
        /* Do we want to do path grouping? */
        if (!cdev->private->options.pgroup) {
                /* Start initial path verification. */
                cdev->private->state = DEV_STATE_VERIFY;
                cdev->private->flags.doverify = 0;
                ccw_device_verify_start(cdev);
                return 0;
        }
        /* Do a SensePGID first. */
        cdev->private->state = DEV_STATE_SENSE_PGID;
        ccw_device_sense_pgid_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:
                ccw_device_done(cdev, DEV_STATE_NOT_OPER);
                break;
        }
}

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

        if (ccw_device_is_orphan(cdev)) {
                ccw_device_done(cdev, DEV_STATE_OFFLINE);
                return 0;
        }
        sch = to_subchannel(cdev->dev.parent);
        if (stsch(sch->schid, &sch->schib) || !sch->schib.pmcw.dnv)
                return -ENODEV;
        if (cdev->private->state != DEV_STATE_ONLINE) {
                if (sch->schib.scsw.actl != 0)
                        return -EBUSY;
                return -EINVAL;
        }
        if (sch->schib.scsw.actl != 0)
                return -EBUSY;
        /* Are we doing path grouping? */
        if (!cdev->private->options.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 timeout in device online/offline process.
 */
static void
ccw_device_onoff_timeout(struct ccw_device *cdev, enum dev_event dev_event)
{
        int ret;

        ret = ccw_device_cancel_halt_clear(cdev);
        switch (ret) {
        case 0:
                ccw_device_done(cdev, DEV_STATE_BOXED);
                break;
        case -ENODEV:
                ccw_device_done(cdev, DEV_STATE_NOT_OPER);
                break;
        default:
                ccw_device_set_timeout(cdev, 3*HZ);
        }
}

/*
 * Handle not oper event in device recognition.
 */
static void
ccw_device_recog_notoper(struct ccw_device *cdev, enum dev_event dev_event)
{
        ccw_device_recog_done(cdev, DEV_STATE_NOT_OPER);
}

/*
 * Handle not operational event while offline.
 */
static void
ccw_device_offline_notoper(struct ccw_device *cdev, enum dev_event dev_event)
{
        struct subchannel *sch;

        cdev->private->state = DEV_STATE_NOT_OPER;
        sch = to_subchannel(cdev->dev.parent);
        if (get_device(&cdev->dev)) {
                PREPARE_WORK(&cdev->private->kick_work,
                             ccw_device_call_sch_unregister);
                queue_work(ccw_device_work, &cdev->private->kick_work);
        }
        wake_up(&cdev->private->wait_q);
}

/*
 * Handle not operational event while online.
 */
static void
ccw_device_online_notoper(struct ccw_device *cdev, enum dev_event dev_event)
{
        struct subchannel *sch;
        int ret;

        sch = to_subchannel(cdev->dev.parent);
        if (sch->driver->notify) {
                spin_unlock_irq(cdev->ccwlock);
                ret = sch->driver->notify(&sch->dev,
                                          sch->lpm ? CIO_GONE : CIO_NO_PATH);
                spin_lock_irq(cdev->ccwlock);
        } else
                ret = 0;
        if (ret) {
                ccw_device_set_timeout(cdev, 0);
                cdev->private->flags.fake_irb = 0;
                cdev->private->state = DEV_STATE_DISCONNECTED;
                wake_up(&cdev->private->wait_q);
                return;
        }
        cdev->private->state = DEV_STATE_NOT_OPER;
        cio_disable_subchannel(sch);
        if (sch->schib.scsw.actl != 0) {
                // FIXME: not-oper indication to device driver ?
                ccw_device_call_handler(cdev);
        }
        if (get_device(&cdev->dev)) {
                PREPARE_WORK(&cdev->private->kick_work,
                             ccw_device_call_sch_unregister);
                queue_work(ccw_device_work, &cdev->private->kick_work);
        }
        wake_up(&cdev->private->wait_q);
}

/*
 * 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.
         */
        stsch(sch->schid, &sch->schib);

        if (sch->schib.scsw.actl != 0 ||
            (sch->schib.scsw.stctl & SCSW_STCTL_STATUS_PEND) ||
            (cdev->private->irb.scsw.stctl & SCSW_STCTL_STATUS_PEND)) {
                /*
                 * No final status yet or final status not yet delivered
                 * to the device driver. Can't do path verfication 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;
        cdev->private->flags.doverify = 0;
        ccw_device_verify_start(cdev);
}

/*
 * 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;

        irb = (struct irb *) __LC_IRB;
        /* Check for unsolicited interrupt. */
        if ((irb->scsw.stctl ==
                        (SCSW_STCTL_STATUS_PEND | SCSW_STCTL_ALERT_STATUS))
            && (!irb->scsw.cc)) {
                if ((irb->scsw.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 (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);
        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 == -ENODEV) {
                struct subchannel *sch;

                sch = to_subchannel(cdev->dev.parent);
                if (!sch->lpm) {
                        PREPARE_WORK(&cdev->private->kick_work,
                                     ccw_device_nopath_notify);
                        queue_work(ccw_device_notify_work,
                                   &cdev->private->kick_work);
                } else
                        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 *) __LC_IRB;
        /* Check for unsolicited interrupt. */
        if (irb->scsw.stctl ==
                        (SCSW_STCTL_STATUS_PEND | SCSW_STCTL_ALERT_STATUS)) {
                if (irb->scsw.cc == 1)
                        /* Basic sense hasn't started. Try again. */
                        ccw_device_do_sense(cdev, irb);
                else {
                        printk(KERN_INFO "Huh? %s(%s): unsolicited "
                               "interrupt...\n",
                               __FUNCTION__, cdev->dev.bus_id);
                        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 (irb->scsw.fctl & (SCSW_FCTL_CLEAR_FUNC | SCSW_FCTL_HALT_FUNC)) {
                /* Retry Basic Sense if requested. */
                if (cdev->private->flags.intretry) {
                        cdev->private->flags.intretry = 0;
                        ccw_device_do_sense(cdev, irb);
                        return;
                }
                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;
        /* 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_clear_verify(struct ccw_device *cdev, enum dev_event dev_event)
{
        struct irb *irb;

        irb = (struct irb *) __LC_IRB;
        /* Accumulate status. We don't do basic sense. */
        ccw_device_accumulate_irb(cdev, irb);
        /* Remember to clear irb to avoid residuals. */
        memset(&cdev->private->irb, 0, sizeof(struct irb));
        /* Try to start delayed device verification. */
        ccw_device_online_verify(cdev, 0);
        /* Note: Don't call handler for cio initiated clear! */
}

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

        sch = to_subchannel(cdev->dev.parent);
        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 device_kill_io(struct subchannel *sch)
{
        int ret;
        struct ccw_device *cdev;

        cdev = sch->dev.driver_data;
        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_stlck_done(struct ccw_device *cdev, enum dev_event dev_event)
{
        struct irb *irb;

        switch (dev_event) {
        case DEV_EVENT_INTERRUPT:
                irb = (struct irb *) __LC_IRB;
                /* Check for unsolicited interrupt. */
                if ((irb->scsw.stctl ==
                     (SCSW_STCTL_STATUS_PEND | SCSW_STCTL_ALERT_STATUS)) &&
                    (!irb->scsw.cc))
                        /* FIXME: we should restart stlck here, but this
                         * is extremely unlikely ... */
                        goto out_wakeup;

                ccw_device_accumulate_irb(cdev, irb);
                /* We don't care about basic sense etc. */
                break;
        default: /* timeout */
                break;
        }
out_wakeup:
        wake_up(&cdev->private->wait_q);
}

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, sch->schib.pmcw.isc) != 0)
                /* Couldn't enable the subchannel for i/o. Sick device. */
                return;

        /* After 60s the device recognition is considered to have failed. */
        ccw_device_set_timeout(cdev, 60*HZ);

        cdev->private->state = DEV_STATE_DISCONNECTED_SENSE_ID;
        ccw_device_sense_id_start(cdev);
}

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

        if (!sch->dev.driver_data)
                return;
        cdev = sch->dev.driver_data;
        if (cdev->private->state != DEV_STATE_DISCONNECTED)
                return;

        /* Update some values. */
        if (stsch(sch->schid, &sch->schib))
                return;
        if (!sch->schib.pmcw.dnv)
                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;
        /* Re-set some bits in the pmcw that were lost. */
        sch->schib.pmcw.isc = 3;
        sch->schib.pmcw.csense = 1;
        sch->schib.pmcw.ena = 0;
        if ((sch->lpm & (sch->lpm - 1)) != 0)
                sch->schib.pmcw.mp = 1;
        sch->schib.pmcw.intparm = (__u32)(unsigned long)sch;
        /* 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) {
                PREPARE_WORK(&cdev->private->kick_work,
                             ccw_device_move_to_orphanage);
                queue_work(ccw_device_work, &cdev->private->kick_work);
        } else
                ccw_device_start_id(cdev, 0);
}

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

        sch = to_subchannel(cdev->dev.parent);
        /*
         * An interrupt in state offline means a previous disable was not
         * successful. Try 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);
        if (dev_event == DEV_EVENT_NOTOPER)
                cdev->private->state = DEV_STATE_NOT_OPER;
        else
                cdev->private->state = DEV_STATE_OFFLINE;
        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);
        switch (ret) {
        case 0:
                cdev->private->state = DEV_STATE_OFFLINE;
                wake_up(&cdev->private->wait_q);
                break;
        case -ENODEV:
                cdev->private->state = DEV_STATE_NOT_OPER;
                wake_up(&cdev->private->wait_q);
                break;
        default:
                ccw_device_set_timeout(cdev, HZ/10);
        }
}

/*
 * 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)
{
}

/*
 * Bug operation action. 
 */
static void
ccw_device_bug(struct ccw_device *cdev, enum dev_event dev_event)
{
        printk(KERN_EMERG "dev_jumptable[%i][%i] == NULL\n",
               cdev->private->state, dev_event);
        BUG();
}

/*
 * 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_bug,
                [DEV_EVENT_TIMEOUT]     = ccw_device_nop,
                [DEV_EVENT_VERIFY]      = ccw_device_nop,
        },
        [DEV_STATE_SENSE_PGID] = {
                [DEV_EVENT_NOTOPER]     = ccw_device_online_notoper,
                [DEV_EVENT_INTERRUPT]   = ccw_device_sense_pgid_irq,
                [DEV_EVENT_TIMEOUT]     = ccw_device_onoff_timeout,
                [DEV_EVENT_VERIFY]      = ccw_device_nop,
        },
        [DEV_STATE_SENSE_ID] = {
                [DEV_EVENT_NOTOPER]     = ccw_device_recog_notoper,
                [DEV_EVENT_INTERRUPT]   = ccw_device_sense_id_irq,
                [DEV_EVENT_TIMEOUT]     = ccw_device_recog_timeout,
                [DEV_EVENT_VERIFY]      = ccw_device_nop,
        },
        [DEV_STATE_OFFLINE] = {
                [DEV_EVENT_NOTOPER]     = ccw_device_offline_notoper,
                [DEV_EVENT_INTERRUPT]   = ccw_device_offline_irq,
                [DEV_EVENT_TIMEOUT]     = ccw_device_nop,
                [DEV_EVENT_VERIFY]      = ccw_device_nop,
        },
        [DEV_STATE_VERIFY] = {
                [DEV_EVENT_NOTOPER]     = ccw_device_online_notoper,
                [DEV_EVENT_INTERRUPT]   = ccw_device_verify_irq,
                [DEV_EVENT_TIMEOUT]     = ccw_device_onoff_timeout,
                [DEV_EVENT_VERIFY]      = ccw_device_delay_verify,
        },
        [DEV_STATE_ONLINE] = {
                [DEV_EVENT_NOTOPER]     = ccw_device_online_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_online_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_online_notoper,
                [DEV_EVENT_INTERRUPT]   = ccw_device_disband_irq,
                [DEV_EVENT_TIMEOUT]     = ccw_device_onoff_timeout,
                [DEV_EVENT_VERIFY]      = ccw_device_nop,
        },
        [DEV_STATE_BOXED] = {
                [DEV_EVENT_NOTOPER]     = ccw_device_offline_notoper,
                [DEV_EVENT_INTERRUPT]   = ccw_device_stlck_done,
                [DEV_EVENT_TIMEOUT]     = ccw_device_stlck_done,
                [DEV_EVENT_VERIFY]      = ccw_device_nop,
        },
        /* states to wait for i/o completion before doing something */
        [DEV_STATE_CLEAR_VERIFY] = {
                [DEV_EVENT_NOTOPER]     = ccw_device_online_notoper,
                [DEV_EVENT_INTERRUPT]   = ccw_device_clear_verify,
                [DEV_EVENT_TIMEOUT]     = ccw_device_nop,
                [DEV_EVENT_VERIFY]      = ccw_device_nop,
        },
        [DEV_STATE_TIMEOUT_KILL] = {
                [DEV_EVENT_NOTOPER]     = ccw_device_online_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_bug,
                [DEV_EVENT_VERIFY]      = ccw_device_start_id,
        },
        [DEV_STATE_DISCONNECTED_SENSE_ID] = {
                [DEV_EVENT_NOTOPER]     = ccw_device_recog_notoper,
                [DEV_EVENT_INTERRUPT]   = ccw_device_sense_id_irq,
                [DEV_EVENT_TIMEOUT]     = ccw_device_recog_timeout,
                [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,
        },
};

/*
 * io_subchannel_irq is called for "real" interrupts or for status
 * pending conditions on msch.
 */
void
io_subchannel_irq (struct device *pdev)
{
        struct ccw_device *cdev;

        cdev = to_subchannel(pdev)->dev.driver_data;

        CIO_TRACE_EVENT (3, "IRQ");
        CIO_TRACE_EVENT (3, pdev->bus_id);
        if (cdev)
                dev_fsm_event(cdev, DEV_EVENT_INTERRUPT);
}

EXPORT_SYMBOL_GPL(ccw_device_set_timeout);