[S390] cio: Rework css driver.

[linux-2.6/verdex.git] / drivers / s390 / cio / device.c

/*
 *  drivers/s390/cio/device.c
 *  bus driver for ccw devices
 *
 *    Copyright IBM Corp. 2002,2008
 *    Author(s): Arnd Bergmann (arndb@de.ibm.com)
 *               Cornelia Huck (cornelia.huck@de.ibm.com)
 *               Martin Schwidefsky (schwidefsky@de.ibm.com)
 */
#include <linux/module.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/device.h>
#include <linux/workqueue.h>
#include <linux/timer.h>

#include <asm/ccwdev.h>
#include <asm/cio.h>
#include <asm/param.h>          /* HZ */
#include <asm/cmb.h>

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

static struct timer_list recovery_timer;
static DEFINE_SPINLOCK(recovery_lock);
static int recovery_phase;
static const unsigned long recovery_delay[] = { 3, 30, 300 };

/******************* bus type handling ***********************/

/* The Linux driver model distinguishes between a bus type and
 * the bus itself. Of course we only have one channel
 * subsystem driver and one channel system per machine, but
 * we still use the abstraction. T.R. says it's a good idea. */
static int
ccw_bus_match (struct device * dev, struct device_driver * drv)
{
        struct ccw_device *cdev = to_ccwdev(dev);
        struct ccw_driver *cdrv = to_ccwdrv(drv);
        const struct ccw_device_id *ids = cdrv->ids, *found;

        if (!ids)
                return 0;

        found = ccw_device_id_match(ids, &cdev->id);
        if (!found)
                return 0;

        cdev->id.driver_info = found->driver_info;

        return 1;
}

/* Store modalias string delimited by prefix/suffix string into buffer with
 * specified size. Return length of resulting string (excluding trailing '\0')
 * even if string doesn't fit buffer (snprintf semantics). */
static int snprint_alias(char *buf, size_t size,
                         struct ccw_device_id *id, const char *suffix)
{
        int len;

        len = snprintf(buf, size, "ccw:t%04Xm%02X", id->cu_type, id->cu_model);
        if (len > size)
                return len;
        buf += len;
        size -= len;

        if (id->dev_type != 0)
                len += snprintf(buf, size, "dt%04Xdm%02X%s", id->dev_type,
                                id->dev_model, suffix);
        else
                len += snprintf(buf, size, "dtdm%s", suffix);

        return len;
}

/* Set up environment variables for ccw device uevent. Return 0 on success,
 * non-zero otherwise. */
static int ccw_uevent(struct device *dev, struct kobj_uevent_env *env)
{
        struct ccw_device *cdev = to_ccwdev(dev);
        struct ccw_device_id *id = &(cdev->id);
        int ret;
        char modalias_buf[30];

        /* CU_TYPE= */
        ret = add_uevent_var(env, "CU_TYPE=%04X", id->cu_type);
        if (ret)
                return ret;

        /* CU_MODEL= */
        ret = add_uevent_var(env, "CU_MODEL=%02X", id->cu_model);
        if (ret)
                return ret;

        /* The next two can be zero, that's ok for us */
        /* DEV_TYPE= */
        ret = add_uevent_var(env, "DEV_TYPE=%04X", id->dev_type);
        if (ret)
                return ret;

        /* DEV_MODEL= */
        ret = add_uevent_var(env, "DEV_MODEL=%02X", id->dev_model);
        if (ret)
                return ret;

        /* MODALIAS=  */
        snprint_alias(modalias_buf, sizeof(modalias_buf), id, "");
        ret = add_uevent_var(env, "MODALIAS=%s", modalias_buf);
        return ret;
}

struct bus_type ccw_bus_type;

static void io_subchannel_irq(struct subchannel *);
static int io_subchannel_probe(struct subchannel *);
static int io_subchannel_remove(struct subchannel *);
static void io_subchannel_shutdown(struct subchannel *);
static int io_subchannel_sch_event(struct subchannel *, int);
static int io_subchannel_chp_event(struct subchannel *, void *, int);

static struct css_driver io_subchannel_driver = {
        .owner = THIS_MODULE,
        .subchannel_type = SUBCHANNEL_TYPE_IO,
        .name = "io_subchannel",
        .irq = io_subchannel_irq,
        .sch_event = io_subchannel_sch_event,
        .chp_event = io_subchannel_chp_event,
        .probe = io_subchannel_probe,
        .remove = io_subchannel_remove,
        .shutdown = io_subchannel_shutdown,
};

struct workqueue_struct *ccw_device_work;
struct workqueue_struct *ccw_device_notify_work;
wait_queue_head_t ccw_device_init_wq;
atomic_t ccw_device_init_count;

static void recovery_func(unsigned long data);

static int __init
init_ccw_bus_type (void)
{
        int ret;

        init_waitqueue_head(&ccw_device_init_wq);
        atomic_set(&ccw_device_init_count, 0);
        setup_timer(&recovery_timer, recovery_func, 0);

        ccw_device_work = create_singlethread_workqueue("cio");
        if (!ccw_device_work)
                return -ENOMEM; /* FIXME: better errno ? */
        ccw_device_notify_work = create_singlethread_workqueue("cio_notify");
        if (!ccw_device_notify_work) {
                ret = -ENOMEM; /* FIXME: better errno ? */
                goto out_err;
        }
        slow_path_wq = create_singlethread_workqueue("kslowcrw");
        if (!slow_path_wq) {
                ret = -ENOMEM; /* FIXME: better errno ? */
                goto out_err;
        }
        if ((ret = bus_register (&ccw_bus_type)))
                goto out_err;

        ret = css_driver_register(&io_subchannel_driver);
        if (ret)
                goto out_err;

        wait_event(ccw_device_init_wq,
                   atomic_read(&ccw_device_init_count) == 0);
        flush_workqueue(ccw_device_work);
        return 0;
out_err:
        if (ccw_device_work)
                destroy_workqueue(ccw_device_work);
        if (ccw_device_notify_work)
                destroy_workqueue(ccw_device_notify_work);
        if (slow_path_wq)
                destroy_workqueue(slow_path_wq);
        return ret;
}

static void __exit
cleanup_ccw_bus_type (void)
{
        css_driver_unregister(&io_subchannel_driver);
        bus_unregister(&ccw_bus_type);
        destroy_workqueue(ccw_device_notify_work);
        destroy_workqueue(ccw_device_work);
}

subsys_initcall(init_ccw_bus_type);
module_exit(cleanup_ccw_bus_type);

/************************ device handling **************************/

/*
 * A ccw_device has some interfaces in sysfs in addition to the
 * standard ones.
 * The following entries are designed to export the information which
 * resided in 2.4 in /proc/subchannels. Subchannel and device number
 * are obvious, so they don't have an entry :)
 * TODO: Split chpids and pimpampom up? Where is "in use" in the tree?
 */
static ssize_t
chpids_show (struct device * dev, struct device_attribute *attr, char * buf)
{
        struct subchannel *sch = to_subchannel(dev);
        struct chsc_ssd_info *ssd = &sch->ssd_info;
        ssize_t ret = 0;
        int chp;
        int mask;

        for (chp = 0; chp < 8; chp++) {
                mask = 0x80 >> chp;
                if (ssd->path_mask & mask)
                        ret += sprintf(buf + ret, "%02x ", ssd->chpid[chp].id);
                else
                        ret += sprintf(buf + ret, "00 ");
        }
        ret += sprintf (buf+ret, "\n");
        return min((ssize_t)PAGE_SIZE, ret);
}

static ssize_t
pimpampom_show (struct device * dev, struct device_attribute *attr, char * buf)
{
        struct subchannel *sch = to_subchannel(dev);
        struct pmcw *pmcw = &sch->schib.pmcw;

        return sprintf (buf, "%02x %02x %02x\n",
                        pmcw->pim, pmcw->pam, pmcw->pom);
}

static ssize_t
devtype_show (struct device *dev, struct device_attribute *attr, char *buf)
{
        struct ccw_device *cdev = to_ccwdev(dev);
        struct ccw_device_id *id = &(cdev->id);

        if (id->dev_type != 0)
                return sprintf(buf, "%04x/%02x\n",
                                id->dev_type, id->dev_model);
        else
                return sprintf(buf, "n/a\n");
}

static ssize_t
cutype_show (struct device *dev, struct device_attribute *attr, char *buf)
{
        struct ccw_device *cdev = to_ccwdev(dev);
        struct ccw_device_id *id = &(cdev->id);

        return sprintf(buf, "%04x/%02x\n",
                       id->cu_type, id->cu_model);
}

static ssize_t
modalias_show (struct device *dev, struct device_attribute *attr, char *buf)
{
        struct ccw_device *cdev = to_ccwdev(dev);
        struct ccw_device_id *id = &(cdev->id);
        int len;

        len = snprint_alias(buf, PAGE_SIZE, id, "\n");

        return len > PAGE_SIZE ? PAGE_SIZE : len;
}

static ssize_t
online_show (struct device *dev, struct device_attribute *attr, char *buf)
{
        struct ccw_device *cdev = to_ccwdev(dev);

        return sprintf(buf, cdev->online ? "1\n" : "0\n");
}

int ccw_device_is_orphan(struct ccw_device *cdev)
{
        return sch_is_pseudo_sch(to_subchannel(cdev->dev.parent));
}

static void ccw_device_unregister(struct ccw_device *cdev)
{
        if (test_and_clear_bit(1, &cdev->private->registered))
                device_del(&cdev->dev);
}

static void ccw_device_remove_orphan_cb(struct device *dev)
{
        struct ccw_device *cdev = to_ccwdev(dev);

        ccw_device_unregister(cdev);
        put_device(&cdev->dev);
}

static void ccw_device_remove_sch_cb(struct device *dev)
{
        struct subchannel *sch;

        sch = to_subchannel(dev);
        css_sch_device_unregister(sch);
        /* Reset intparm to zeroes. */
        sch->schib.pmcw.intparm = 0;
        cio_modify(sch);
        put_device(&sch->dev);
}

static void
ccw_device_remove_disconnected(struct ccw_device *cdev)
{
        unsigned long flags;
        int rc;

        /*
         * Forced offline in disconnected state means
         * 'throw away device'.
         */
        if (ccw_device_is_orphan(cdev)) {
                /*
                 * Deregister ccw device.
                 * Unfortunately, we cannot do this directly from the
                 * attribute method.
                 */
                spin_lock_irqsave(cdev->ccwlock, flags);
                cdev->private->state = DEV_STATE_NOT_OPER;
                spin_unlock_irqrestore(cdev->ccwlock, flags);
                rc = device_schedule_callback(&cdev->dev,
                                              ccw_device_remove_orphan_cb);
                if (rc)
                        CIO_MSG_EVENT(0, "Couldn't unregister orphan "
                                      "0.%x.%04x\n",
                                      cdev->private->dev_id.ssid,
                                      cdev->private->dev_id.devno);
                return;
        }
        /* Deregister subchannel, which will kill the ccw device. */
        rc = device_schedule_callback(cdev->dev.parent,
                                      ccw_device_remove_sch_cb);
        if (rc)
                CIO_MSG_EVENT(0, "Couldn't unregister disconnected device "
                              "0.%x.%04x\n",
                              cdev->private->dev_id.ssid,
                              cdev->private->dev_id.devno);
}

/**
 * ccw_device_set_offline() - disable a ccw device for I/O
 * @cdev: target ccw device
 *
 * This function calls the driver's set_offline() function for @cdev, if
 * given, and then disables @cdev.
 * Returns:
 *   %0 on success and a negative error value on failure.
 * Context:
 *  enabled, ccw device lock not held
 */
int ccw_device_set_offline(struct ccw_device *cdev)
{
        int ret;

        if (!cdev)
                return -ENODEV;
        if (!cdev->online || !cdev->drv)
                return -EINVAL;

        if (cdev->drv->set_offline) {
                ret = cdev->drv->set_offline(cdev);
                if (ret != 0)
                        return ret;
        }
        cdev->online = 0;
        spin_lock_irq(cdev->ccwlock);
        ret = ccw_device_offline(cdev);
        if (ret == -ENODEV) {
                if (cdev->private->state != DEV_STATE_NOT_OPER) {
                        cdev->private->state = DEV_STATE_OFFLINE;
                        dev_fsm_event(cdev, DEV_EVENT_NOTOPER);
                }
                spin_unlock_irq(cdev->ccwlock);
                return ret;
        }
        spin_unlock_irq(cdev->ccwlock);
        if (ret == 0)
                wait_event(cdev->private->wait_q, dev_fsm_final_state(cdev));
        else {
                CIO_MSG_EVENT(0, "ccw_device_offline returned %d, "
                              "device 0.%x.%04x\n",
                              ret, cdev->private->dev_id.ssid,
                              cdev->private->dev_id.devno);
                cdev->online = 1;
        }
        return ret;
}

/**
 * ccw_device_set_online() - enable a ccw device for I/O
 * @cdev: target ccw device
 *
 * This function first enables @cdev and then calls the driver's set_online()
 * function for @cdev, if given. If set_online() returns an error, @cdev is
 * disabled again.
 * Returns:
 *   %0 on success and a negative error value on failure.
 * Context:
 *  enabled, ccw device lock not held
 */
int ccw_device_set_online(struct ccw_device *cdev)
{
        int ret;

        if (!cdev)
                return -ENODEV;
        if (cdev->online || !cdev->drv)
                return -EINVAL;

        spin_lock_irq(cdev->ccwlock);
        ret = ccw_device_online(cdev);
        spin_unlock_irq(cdev->ccwlock);
        if (ret == 0)
                wait_event(cdev->private->wait_q, dev_fsm_final_state(cdev));
        else {
                CIO_MSG_EVENT(0, "ccw_device_online returned %d, "
                              "device 0.%x.%04x\n",
                              ret, cdev->private->dev_id.ssid,
                              cdev->private->dev_id.devno);
                return ret;
        }
        if (cdev->private->state != DEV_STATE_ONLINE)
                return -ENODEV;
        if (!cdev->drv->set_online || cdev->drv->set_online(cdev) == 0) {
                cdev->online = 1;
                return 0;
        }
        spin_lock_irq(cdev->ccwlock);
        ret = ccw_device_offline(cdev);
        spin_unlock_irq(cdev->ccwlock);
        if (ret == 0)
                wait_event(cdev->private->wait_q, dev_fsm_final_state(cdev));
        else
                CIO_MSG_EVENT(0, "ccw_device_offline returned %d, "
                              "device 0.%x.%04x\n",
                              ret, cdev->private->dev_id.ssid,
                              cdev->private->dev_id.devno);
        return (ret == 0) ? -ENODEV : ret;
}

static void online_store_handle_offline(struct ccw_device *cdev)
{
        if (cdev->private->state == DEV_STATE_DISCONNECTED)
                ccw_device_remove_disconnected(cdev);
        else if (cdev->drv && cdev->drv->set_offline)
                ccw_device_set_offline(cdev);
}

static int online_store_recog_and_online(struct ccw_device *cdev)
{
        int ret;

        /* Do device recognition, if needed. */
        if (cdev->id.cu_type == 0) {
                ret = ccw_device_recognition(cdev);
                if (ret) {
                        CIO_MSG_EVENT(0, "Couldn't start recognition "
                                      "for device 0.%x.%04x (ret=%d)\n",
                                      cdev->private->dev_id.ssid,
                                      cdev->private->dev_id.devno, ret);
                        return ret;
                }
                wait_event(cdev->private->wait_q,
                           cdev->private->flags.recog_done);
        }
        if (cdev->drv && cdev->drv->set_online)
                ccw_device_set_online(cdev);
        return 0;
}
static void online_store_handle_online(struct ccw_device *cdev, int force)
{
        int ret;

        ret = online_store_recog_and_online(cdev);
        if (ret)
                return;
        if (force && cdev->private->state == DEV_STATE_BOXED) {
                ret = ccw_device_stlck(cdev);
                if (ret) {
                        dev_warn(&cdev->dev,
                                 "ccw_device_stlck returned %d!\n", ret);
                        return;
                }
                if (cdev->id.cu_type == 0)
                        cdev->private->state = DEV_STATE_NOT_OPER;
                online_store_recog_and_online(cdev);
        }

}

static ssize_t online_store (struct device *dev, struct device_attribute *attr,
                             const char *buf, size_t count)
{
        struct ccw_device *cdev = to_ccwdev(dev);
        int force, ret;
        unsigned long i;

        if (atomic_cmpxchg(&cdev->private->onoff, 0, 1) != 0)
                return -EAGAIN;

        if (cdev->drv && !try_module_get(cdev->drv->owner)) {
                atomic_set(&cdev->private->onoff, 0);
                return -EINVAL;
        }
        if (!strncmp(buf, "force\n", count)) {
                force = 1;
                i = 1;
                ret = 0;
        } else {
                force = 0;
                ret = strict_strtoul(buf, 16, &i);
        }
        if (ret)
                goto out;
        switch (i) {
        case 0:
                online_store_handle_offline(cdev);
                ret = count;
                break;
        case 1:
                online_store_handle_online(cdev, force);
                ret = count;
                break;
        default:
                ret = -EINVAL;
        }
out:
        if (cdev->drv)
                module_put(cdev->drv->owner);
        atomic_set(&cdev->private->onoff, 0);
        return ret;
}

static ssize_t
available_show (struct device *dev, struct device_attribute *attr, char *buf)
{
        struct ccw_device *cdev = to_ccwdev(dev);
        struct subchannel *sch;

        if (ccw_device_is_orphan(cdev))
                return sprintf(buf, "no device\n");
        switch (cdev->private->state) {
        case DEV_STATE_BOXED:
                return sprintf(buf, "boxed\n");
        case DEV_STATE_DISCONNECTED:
        case DEV_STATE_DISCONNECTED_SENSE_ID:
        case DEV_STATE_NOT_OPER:
                sch = to_subchannel(dev->parent);
                if (!sch->lpm)
                        return sprintf(buf, "no path\n");
                else
                        return sprintf(buf, "no device\n");
        default:
                /* All other states considered fine. */
                return sprintf(buf, "good\n");
        }
}

static DEVICE_ATTR(chpids, 0444, chpids_show, NULL);
static DEVICE_ATTR(pimpampom, 0444, pimpampom_show, NULL);
static DEVICE_ATTR(devtype, 0444, devtype_show, NULL);
static DEVICE_ATTR(cutype, 0444, cutype_show, NULL);
static DEVICE_ATTR(modalias, 0444, modalias_show, NULL);
static DEVICE_ATTR(online, 0644, online_show, online_store);
static DEVICE_ATTR(availability, 0444, available_show, NULL);

static struct attribute *io_subchannel_attrs[] = {
        &dev_attr_chpids.attr,
        &dev_attr_pimpampom.attr,
        NULL,
};

static struct attribute_group io_subchannel_attr_group = {
        .attrs = io_subchannel_attrs,
};

static struct attribute * ccwdev_attrs[] = {
        &dev_attr_devtype.attr,
        &dev_attr_cutype.attr,
        &dev_attr_modalias.attr,
        &dev_attr_online.attr,
        &dev_attr_cmb_enable.attr,
        &dev_attr_availability.attr,
        NULL,
};

static struct attribute_group ccwdev_attr_group = {
        .attrs = ccwdev_attrs,
};

static struct attribute_group *ccwdev_attr_groups[] = {
        &ccwdev_attr_group,
        NULL,
};

/* this is a simple abstraction for device_register that sets the
 * correct bus type and adds the bus specific files */
static int ccw_device_register(struct ccw_device *cdev)
{
        struct device *dev = &cdev->dev;
        int ret;

        dev->bus = &ccw_bus_type;

        if ((ret = device_add(dev)))
                return ret;

        set_bit(1, &cdev->private->registered);
        return ret;
}

struct match_data {
        struct ccw_dev_id dev_id;
        struct ccw_device * sibling;
};

static int
match_devno(struct device * dev, void * data)
{
        struct match_data * d = data;
        struct ccw_device * cdev;

        cdev = to_ccwdev(dev);
        if ((cdev->private->state == DEV_STATE_DISCONNECTED) &&
            !ccw_device_is_orphan(cdev) &&
            ccw_dev_id_is_equal(&cdev->private->dev_id, &d->dev_id) &&
            (cdev != d->sibling))
                return 1;
        return 0;
}

static struct ccw_device * get_disc_ccwdev_by_dev_id(struct ccw_dev_id *dev_id,
                                                     struct ccw_device *sibling)
{
        struct device *dev;
        struct match_data data;

        data.dev_id = *dev_id;
        data.sibling = sibling;
        dev = bus_find_device(&ccw_bus_type, NULL, &data, match_devno);

        return dev ? to_ccwdev(dev) : NULL;
}

static int match_orphan(struct device *dev, void *data)
{
        struct ccw_dev_id *dev_id;
        struct ccw_device *cdev;

        dev_id = data;
        cdev = to_ccwdev(dev);
        return ccw_dev_id_is_equal(&cdev->private->dev_id, dev_id);
}

static struct ccw_device *
get_orphaned_ccwdev_by_dev_id(struct channel_subsystem *css,
                              struct ccw_dev_id *dev_id)
{
        struct device *dev;

        dev = device_find_child(&css->pseudo_subchannel->dev, dev_id,
                                match_orphan);

        return dev ? to_ccwdev(dev) : NULL;
}

static void
ccw_device_add_changed(struct work_struct *work)
{
        struct ccw_device_private *priv;
        struct ccw_device *cdev;

        priv = container_of(work, struct ccw_device_private, kick_work);
        cdev = priv->cdev;
        if (device_add(&cdev->dev)) {
                put_device(&cdev->dev);
                return;
        }
        set_bit(1, &cdev->private->registered);
}

void ccw_device_do_unreg_rereg(struct work_struct *work)
{
        struct ccw_device_private *priv;
        struct ccw_device *cdev;
        struct subchannel *sch;

        priv = container_of(work, struct ccw_device_private, kick_work);
        cdev = priv->cdev;
        sch = to_subchannel(cdev->dev.parent);

        ccw_device_unregister(cdev);
        PREPARE_WORK(&cdev->private->kick_work,
                     ccw_device_add_changed);
        queue_work(ccw_device_work, &cdev->private->kick_work);
}

static void
ccw_device_release(struct device *dev)
{
        struct ccw_device *cdev;

        cdev = to_ccwdev(dev);
        kfree(cdev->private);
        kfree(cdev);
}

static struct ccw_device * io_subchannel_allocate_dev(struct subchannel *sch)
{
        struct ccw_device *cdev;

        cdev  = kzalloc(sizeof(*cdev), GFP_KERNEL);
        if (cdev) {
                cdev->private = kzalloc(sizeof(struct ccw_device_private),
                                        GFP_KERNEL | GFP_DMA);
                if (cdev->private)
                        return cdev;
        }
        kfree(cdev);
        return ERR_PTR(-ENOMEM);
}

static int io_subchannel_initialize_dev(struct subchannel *sch,
                                        struct ccw_device *cdev)
{
        cdev->private->cdev = cdev;
        atomic_set(&cdev->private->onoff, 0);
        cdev->dev.parent = &sch->dev;
        cdev->dev.release = ccw_device_release;
        INIT_WORK(&cdev->private->kick_work, NULL);
        cdev->dev.groups = ccwdev_attr_groups;
        /* Do first half of device_register. */
        device_initialize(&cdev->dev);
        if (!get_device(&sch->dev)) {
                if (cdev->dev.release)
                        cdev->dev.release(&cdev->dev);
                return -ENODEV;
        }
        return 0;
}

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

        cdev = io_subchannel_allocate_dev(sch);
        if (!IS_ERR(cdev)) {
                ret = io_subchannel_initialize_dev(sch, cdev);
                if (ret) {
                        kfree(cdev);
                        cdev = ERR_PTR(ret);
                }
        }
        return cdev;
}

static int io_subchannel_recog(struct ccw_device *, struct subchannel *);

static void sch_attach_device(struct subchannel *sch,
                              struct ccw_device *cdev)
{
        css_update_ssd_info(sch);
        spin_lock_irq(sch->lock);
        sch_set_cdev(sch, cdev);
        cdev->private->schid = sch->schid;
        cdev->ccwlock = sch->lock;
        ccw_device_trigger_reprobe(cdev);
        spin_unlock_irq(sch->lock);
}

static void sch_attach_disconnected_device(struct subchannel *sch,
                                           struct ccw_device *cdev)
{
        struct subchannel *other_sch;
        int ret;

        other_sch = to_subchannel(get_device(cdev->dev.parent));
        ret = device_move(&cdev->dev, &sch->dev);
        if (ret) {
                CIO_MSG_EVENT(0, "Moving disconnected device 0.%x.%04x failed "
                              "(ret=%d)!\n", cdev->private->dev_id.ssid,
                              cdev->private->dev_id.devno, ret);
                put_device(&other_sch->dev);
                return;
        }
        sch_set_cdev(other_sch, NULL);
        /* No need to keep a subchannel without ccw device around. */
        css_sch_device_unregister(other_sch);
        put_device(&other_sch->dev);
        sch_attach_device(sch, cdev);
}

static void sch_attach_orphaned_device(struct subchannel *sch,
                                       struct ccw_device *cdev)
{
        int ret;

        /* Try to move the ccw device to its new subchannel. */
        ret = device_move(&cdev->dev, &sch->dev);
        if (ret) {
                CIO_MSG_EVENT(0, "Moving device 0.%x.%04x from orphanage "
                              "failed (ret=%d)!\n",
                              cdev->private->dev_id.ssid,
                              cdev->private->dev_id.devno, ret);
                return;
        }
        sch_attach_device(sch, cdev);
}

static void sch_create_and_recog_new_device(struct subchannel *sch)
{
        struct ccw_device *cdev;

        /* Need to allocate a new ccw device. */
        cdev = io_subchannel_create_ccwdev(sch);
        if (IS_ERR(cdev)) {
                /* OK, we did everything we could... */
                css_sch_device_unregister(sch);
                return;
        }
        spin_lock_irq(sch->lock);
        sch_set_cdev(sch, cdev);
        spin_unlock_irq(sch->lock);
        /* Start recognition for the new ccw device. */
        if (io_subchannel_recog(cdev, sch)) {
                spin_lock_irq(sch->lock);
                sch_set_cdev(sch, NULL);
                spin_unlock_irq(sch->lock);
                if (cdev->dev.release)
                        cdev->dev.release(&cdev->dev);
                css_sch_device_unregister(sch);
        }
}


void ccw_device_move_to_orphanage(struct work_struct *work)
{
        struct ccw_device_private *priv;
        struct ccw_device *cdev;
        struct ccw_device *replacing_cdev;
        struct subchannel *sch;
        int ret;
        struct channel_subsystem *css;
        struct ccw_dev_id dev_id;

        priv = container_of(work, struct ccw_device_private, kick_work);
        cdev = priv->cdev;
        sch = to_subchannel(cdev->dev.parent);
        css = to_css(sch->dev.parent);
        dev_id.devno = sch->schib.pmcw.dev;
        dev_id.ssid = sch->schid.ssid;

        /*
         * Move the orphaned ccw device to the orphanage so the replacing
         * ccw device can take its place on the subchannel.
         */
        ret = device_move(&cdev->dev, &css->pseudo_subchannel->dev);
        if (ret) {
                CIO_MSG_EVENT(0, "Moving device 0.%x.%04x to orphanage failed "
                              "(ret=%d)!\n", cdev->private->dev_id.ssid,
                              cdev->private->dev_id.devno, ret);
                return;
        }
        cdev->ccwlock = css->pseudo_subchannel->lock;
        /*
         * Search for the replacing ccw device
         * - among the disconnected devices
         * - in the orphanage
         */
        replacing_cdev = get_disc_ccwdev_by_dev_id(&dev_id, cdev);
        if (replacing_cdev) {
                sch_attach_disconnected_device(sch, replacing_cdev);
                return;
        }
        replacing_cdev = get_orphaned_ccwdev_by_dev_id(css, &dev_id);
        if (replacing_cdev) {
                sch_attach_orphaned_device(sch, replacing_cdev);
                return;
        }
        sch_create_and_recog_new_device(sch);
}

/*
 * Register recognized device.
 */
static void
io_subchannel_register(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;
        sch = to_subchannel(cdev->dev.parent);
        css_update_ssd_info(sch);
        /*
         * io_subchannel_register() will also be called after device
         * recognition has been done for a boxed device (which will already
         * be registered). We need to reprobe since we may now have sense id
         * information.
         */
        if (klist_node_attached(&cdev->dev.knode_parent)) {
                if (!cdev->drv) {
                        ret = device_reprobe(&cdev->dev);
                        if (ret)
                                /* We can't do much here. */
                                CIO_MSG_EVENT(0, "device_reprobe() returned"
                                              " %d for 0.%x.%04x\n", ret,
                                              cdev->private->dev_id.ssid,
                                              cdev->private->dev_id.devno);
                }
                goto out;
        }
        /*
         * Now we know this subchannel will stay, we can throw
         * our delayed uevent.
         */
        sch->dev.uevent_suppress = 0;
        kobject_uevent(&sch->dev.kobj, KOBJ_ADD);
        /* make it known to the system */
        ret = ccw_device_register(cdev);
        if (ret) {
                CIO_MSG_EVENT(0, "Could not register ccw dev 0.%x.%04x: %d\n",
                              cdev->private->dev_id.ssid,
                              cdev->private->dev_id.devno, ret);
                put_device(&cdev->dev);
                spin_lock_irqsave(sch->lock, flags);
                sch_set_cdev(sch, NULL);
                spin_unlock_irqrestore(sch->lock, flags);
                kfree (cdev->private);
                kfree (cdev);
                put_device(&sch->dev);
                if (atomic_dec_and_test(&ccw_device_init_count))
                        wake_up(&ccw_device_init_wq);
                return;
        }
        put_device(&cdev->dev);
out:
        cdev->private->flags.recog_done = 1;
        put_device(&sch->dev);
        wake_up(&cdev->private->wait_q);
        if (atomic_dec_and_test(&ccw_device_init_count))
                wake_up(&ccw_device_init_wq);
}

static void ccw_device_call_sch_unregister(struct work_struct *work)
{
        struct ccw_device_private *priv;
        struct ccw_device *cdev;
        struct subchannel *sch;

        priv = container_of(work, struct ccw_device_private, kick_work);
        cdev = priv->cdev;
        sch = to_subchannel(cdev->dev.parent);
        css_sch_device_unregister(sch);
        /* Reset intparm to zeroes. */
        sch->schib.pmcw.intparm = 0;
        cio_modify(sch);
        put_device(&cdev->dev);
        put_device(&sch->dev);
}

/*
 * subchannel recognition done. Called from the state machine.
 */
void
io_subchannel_recog_done(struct ccw_device *cdev)
{
        struct subchannel *sch;

        if (css_init_done == 0) {
                cdev->private->flags.recog_done = 1;
                return;
        }
        switch (cdev->private->state) {
        case DEV_STATE_NOT_OPER:
                cdev->private->flags.recog_done = 1;
                /* Remove device found not operational. */
                if (!get_device(&cdev->dev))
                        break;
                sch = to_subchannel(cdev->dev.parent);
                PREPARE_WORK(&cdev->private->kick_work,
                             ccw_device_call_sch_unregister);
                queue_work(slow_path_wq, &cdev->private->kick_work);
                if (atomic_dec_and_test(&ccw_device_init_count))
                        wake_up(&ccw_device_init_wq);
                break;
        case DEV_STATE_BOXED:
                /* Device did not respond in time. */
        case DEV_STATE_OFFLINE:
                /* 
                 * We can't register the device in interrupt context so
                 * we schedule a work item.
                 */
                if (!get_device(&cdev->dev))
                        break;
                PREPARE_WORK(&cdev->private->kick_work,
                             io_subchannel_register);
                queue_work(slow_path_wq, &cdev->private->kick_work);
                break;
        }
}

static int
io_subchannel_recog(struct ccw_device *cdev, struct subchannel *sch)
{
        int rc;
        struct ccw_device_private *priv;

        sch_set_cdev(sch, cdev);
        cdev->ccwlock = sch->lock;

        /* Init private data. */
        priv = cdev->private;
        priv->dev_id.devno = sch->schib.pmcw.dev;
        priv->dev_id.ssid = sch->schid.ssid;
        priv->schid = sch->schid;
        priv->state = DEV_STATE_NOT_OPER;
        INIT_LIST_HEAD(&priv->cmb_list);
        init_waitqueue_head(&priv->wait_q);
        init_timer(&priv->timer);

        /* Set an initial name for the device. */
        snprintf (cdev->dev.bus_id, BUS_ID_SIZE, "0.%x.%04x",
                  sch->schid.ssid, sch->schib.pmcw.dev);

        /* Increase counter of devices currently in recognition. */
        atomic_inc(&ccw_device_init_count);

        /* Start async. device sensing. */
        spin_lock_irq(sch->lock);
        rc = ccw_device_recognition(cdev);
        spin_unlock_irq(sch->lock);
        if (rc) {
                if (atomic_dec_and_test(&ccw_device_init_count))
                        wake_up(&ccw_device_init_wq);
        }
        return rc;
}

static void ccw_device_move_to_sch(struct work_struct *work)
{
        struct ccw_device_private *priv;
        int rc;
        struct subchannel *sch;
        struct ccw_device *cdev;
        struct subchannel *former_parent;

        priv = container_of(work, struct ccw_device_private, kick_work);
        sch = priv->sch;
        cdev = priv->cdev;
        former_parent = ccw_device_is_orphan(cdev) ?
                NULL : to_subchannel(get_device(cdev->dev.parent));
        mutex_lock(&sch->reg_mutex);
        /* Try to move the ccw device to its new subchannel. */
        rc = device_move(&cdev->dev, &sch->dev);
        mutex_unlock(&sch->reg_mutex);
        if (rc) {
                CIO_MSG_EVENT(0, "Moving device 0.%x.%04x to subchannel "
                              "0.%x.%04x failed (ret=%d)!\n",
                              cdev->private->dev_id.ssid,
                              cdev->private->dev_id.devno, sch->schid.ssid,
                              sch->schid.sch_no, rc);
                css_sch_device_unregister(sch);
                goto out;
        }
        if (former_parent) {
                spin_lock_irq(former_parent->lock);
                sch_set_cdev(former_parent, NULL);
                spin_unlock_irq(former_parent->lock);
                css_sch_device_unregister(former_parent);
                /* Reset intparm to zeroes. */
                former_parent->schib.pmcw.intparm = 0;
                cio_modify(former_parent);
        }
        sch_attach_device(sch, cdev);
out:
        if (former_parent)
                put_device(&former_parent->dev);
        put_device(&cdev->dev);
}

static void io_subchannel_irq(struct subchannel *sch)
{
        struct ccw_device *cdev;

        cdev = sch_get_cdev(sch);

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

static void io_subchannel_init_fields(struct subchannel *sch)
{
        if (cio_is_console(sch->schid))
                sch->opm = 0xff;
        else
                sch->opm = chp_get_sch_opm(sch);
        sch->lpm = sch->schib.pmcw.pam & sch->opm;
        sch->isc = cio_is_console(sch->schid) ? 1 : 3;

        CIO_MSG_EVENT(6, "Detected device %04x on subchannel 0.%x.%04X"
                      " - PIM = %02X, PAM = %02X, POM = %02X\n",
                      sch->schib.pmcw.dev, sch->schid.ssid,
                      sch->schid.sch_no, sch->schib.pmcw.pim,
                      sch->schib.pmcw.pam, sch->schib.pmcw.pom);
        /* Initially set up some fields in the pmcw. */
        sch->schib.pmcw.ena = 0;
        sch->schib.pmcw.csense = 1;     /* concurrent sense */
        if ((sch->lpm & (sch->lpm - 1)) != 0)
                sch->schib.pmcw.mp = 1; /* multipath mode */
        /* clean up possible residual cmf stuff */
        sch->schib.pmcw.mme = 0;
        sch->schib.pmcw.mbfc = 0;
        sch->schib.pmcw.mbi = 0;
        sch->schib.mba = 0;
}

static int io_subchannel_probe(struct subchannel *sch)
{
        struct ccw_device *cdev;
        int rc;
        unsigned long flags;
        struct ccw_dev_id dev_id;

        cdev = sch_get_cdev(sch);
        if (cdev) {
                rc = sysfs_create_group(&sch->dev.kobj,
                                        &io_subchannel_attr_group);
                if (rc)
                        CIO_MSG_EVENT(0, "Failed to create io subchannel "
                                      "attributes for subchannel "
                                      "0.%x.%04x (rc=%d)\n",
                                      sch->schid.ssid, sch->schid.sch_no, rc);
                /*
                 * This subchannel already has an associated ccw_device.
                 * Throw the delayed uevent for the subchannel, register
                 * the ccw_device and exit. This happens for all early
                 * devices, e.g. the console.
                 */
                sch->dev.uevent_suppress = 0;
                kobject_uevent(&sch->dev.kobj, KOBJ_ADD);
                cdev->dev.groups = ccwdev_attr_groups;
                device_initialize(&cdev->dev);
                ccw_device_register(cdev);
                /*
                 * Check if the device is already online. If it is
                 * the reference count needs to be corrected
                 * (see ccw_device_online and css_init_done for the
                 * ugly details).
                 */
                if (cdev->private->state != DEV_STATE_NOT_OPER &&
                    cdev->private->state != DEV_STATE_OFFLINE &&
                    cdev->private->state != DEV_STATE_BOXED)
                        get_device(&cdev->dev);
                return 0;
        }
        io_subchannel_init_fields(sch);
        /*
         * First check if a fitting device may be found amongst the
         * disconnected devices or in the orphanage.
         */
        dev_id.devno = sch->schib.pmcw.dev;
        dev_id.ssid = sch->schid.ssid;
        rc = sysfs_create_group(&sch->dev.kobj,
                                &io_subchannel_attr_group);
        if (rc)
                return rc;
        /* Allocate I/O subchannel private data. */
        sch->private = kzalloc(sizeof(struct io_subchannel_private),
                               GFP_KERNEL | GFP_DMA);
        if (!sch->private) {
                rc = -ENOMEM;
                goto out_err;
        }
        cdev = get_disc_ccwdev_by_dev_id(&dev_id, NULL);
        if (!cdev)
                cdev = get_orphaned_ccwdev_by_dev_id(to_css(sch->dev.parent),
                                                     &dev_id);
        if (cdev) {
                /*
                 * Schedule moving the device until when we have a registered
                 * subchannel to move to and succeed the probe. We can
                 * unregister later again, when the probe is through.
                 */
                cdev->private->sch = sch;
                PREPARE_WORK(&cdev->private->kick_work,
                             ccw_device_move_to_sch);
                queue_work(slow_path_wq, &cdev->private->kick_work);
                return 0;
        }
        cdev = io_subchannel_create_ccwdev(sch);
        if (IS_ERR(cdev)) {
                rc = PTR_ERR(cdev);
                goto out_err;
        }
        rc = io_subchannel_recog(cdev, sch);
        if (rc) {
                spin_lock_irqsave(sch->lock, flags);
                sch_set_cdev(sch, NULL);
                spin_unlock_irqrestore(sch->lock, flags);
                if (cdev->dev.release)
                        cdev->dev.release(&cdev->dev);
                goto out_err;
        }
        return 0;
out_err:
        kfree(sch->private);
        sysfs_remove_group(&sch->dev.kobj, &io_subchannel_attr_group);
        return rc;
}

static int
io_subchannel_remove (struct subchannel *sch)
{
        struct ccw_device *cdev;
        unsigned long flags;

        cdev = sch_get_cdev(sch);
        if (!cdev)
                return 0;
        /* Set ccw device to not operational and drop reference. */
        spin_lock_irqsave(cdev->ccwlock, flags);
        sch_set_cdev(sch, NULL);
        cdev->private->state = DEV_STATE_NOT_OPER;
        spin_unlock_irqrestore(cdev->ccwlock, flags);
        ccw_device_unregister(cdev);
        put_device(&cdev->dev);
        kfree(sch->private);
        sysfs_remove_group(&sch->dev.kobj, &io_subchannel_attr_group);
        return 0;
}

static int io_subchannel_notify(struct subchannel *sch, int event)
{
        struct ccw_device *cdev;

        cdev = sch_get_cdev(sch);
        if (!cdev)
                return 0;
        return ccw_device_notify(cdev, event);
}

static void io_subchannel_verify(struct subchannel *sch)
{
        struct ccw_device *cdev;

        cdev = sch_get_cdev(sch);
        if (cdev)
                dev_fsm_event(cdev, DEV_EVENT_VERIFY);
}

static int check_for_io_on_path(struct subchannel *sch, int mask)
{
        int cc;

        cc = stsch(sch->schid, &sch->schib);
        if (cc)
                return 0;
        if (sch->schib.scsw.actl && sch->schib.pmcw.lpum == mask)
                return 1;
        return 0;
}

static void terminate_internal_io(struct subchannel *sch,
                                  struct ccw_device *cdev)
{
        if (cio_clear(sch)) {
                /* Recheck device in case clear failed. */
                sch->lpm = 0;
                if (cdev->online)
                        dev_fsm_event(cdev, DEV_EVENT_VERIFY);
                else
                        css_schedule_eval(sch->schid);
                return;
        }
        cdev->private->state = DEV_STATE_CLEAR_VERIFY;
        /* Request retry of internal operation. */
        cdev->private->flags.intretry = 1;
        /* Call handler. */
        if (cdev->handler)
                cdev->handler(cdev, cdev->private->intparm,
                              ERR_PTR(-EIO));
}

static void io_subchannel_terminate_path(struct subchannel *sch, u8 mask)
{
        struct ccw_device *cdev;

        cdev = sch_get_cdev(sch);
        if (!cdev)
                return;
        if (check_for_io_on_path(sch, mask)) {
                if (cdev->private->state == DEV_STATE_ONLINE)
                        ccw_device_kill_io(cdev);
                else {
                        terminate_internal_io(sch, cdev);
                        /* Re-start path verification. */
                        dev_fsm_event(cdev, DEV_EVENT_VERIFY);
                }
        } else
                /* trigger path verification. */
                dev_fsm_event(cdev, DEV_EVENT_VERIFY);

}

static int io_subchannel_chp_event(struct subchannel *sch, void *data,
                                   int event)
{
        int mask;
        struct res_acc_data *res_data;

        res_data = data;
        mask = chp_ssd_get_mask(&sch->ssd_info, res_data);
        if (!mask)
                return 0;
        switch (event) {
        case CHP_VARY_OFF:
                sch->opm &= ~mask;
                sch->lpm &= ~mask;
                io_subchannel_terminate_path(sch, mask);
                break;
        case CHP_VARY_ON:
                sch->opm |= mask;
                sch->lpm |= mask;
                io_subchannel_verify(sch);
                break;
        case CHP_OFFLINE:
                if (stsch(sch->schid, &sch->schib))
                        return -ENXIO;
                if (!css_sch_is_valid(&sch->schib))
                        return -ENODEV;
                io_subchannel_terminate_path(sch, mask);
                break;
        case CHP_ONLINE:
                if (stsch(sch->schid, &sch->schib))
                        return -ENXIO;
                sch->lpm |= mask & sch->opm;
                io_subchannel_verify(sch);
                break;
        }
        return 0;
}

static void
io_subchannel_shutdown(struct subchannel *sch)
{
        struct ccw_device *cdev;
        int ret;

        cdev = sch_get_cdev(sch);

        if (cio_is_console(sch->schid))
                return;
        if (!sch->schib.pmcw.ena)
                /* Nothing to do. */
                return;
        ret = cio_disable_subchannel(sch);
        if (ret != -EBUSY)
                /* Subchannel is disabled, we're done. */
                return;
        cdev->private->state = DEV_STATE_QUIESCE;
        if (cdev->handler)
                cdev->handler(cdev, cdev->private->intparm,
                              ERR_PTR(-EIO));
        ret = ccw_device_cancel_halt_clear(cdev);
        if (ret == -EBUSY) {
                ccw_device_set_timeout(cdev, HZ/10);
                wait_event(cdev->private->wait_q, dev_fsm_final_state(cdev));
        }
        cio_disable_subchannel(sch);
}

static int io_subchannel_get_status(struct subchannel *sch)
{
        struct schib schib;

        if (stsch(sch->schid, &schib) || !schib.pmcw.dnv)
                return CIO_GONE;
        if (sch->schib.pmcw.dnv && (schib.pmcw.dev != sch->schib.pmcw.dev))
                return CIO_REVALIDATE;
        if (!sch->lpm)
                return CIO_NO_PATH;
        return CIO_OPER;
}

static int device_is_disconnected(struct ccw_device *cdev)
{
        if (!cdev)
                return 0;
        return (cdev->private->state == DEV_STATE_DISCONNECTED ||
                cdev->private->state == DEV_STATE_DISCONNECTED_SENSE_ID);
}

static int recovery_check(struct device *dev, void *data)
{
        struct ccw_device *cdev = to_ccwdev(dev);
        int *redo = data;

        spin_lock_irq(cdev->ccwlock);
        switch (cdev->private->state) {
        case DEV_STATE_DISCONNECTED:
                CIO_MSG_EVENT(3, "recovery: trigger 0.%x.%04x\n",
                              cdev->private->dev_id.ssid,
                              cdev->private->dev_id.devno);
                dev_fsm_event(cdev, DEV_EVENT_VERIFY);
                *redo = 1;
                break;
        case DEV_STATE_DISCONNECTED_SENSE_ID:
                *redo = 1;
                break;
        }
        spin_unlock_irq(cdev->ccwlock);

        return 0;
}

static void recovery_work_func(struct work_struct *unused)
{
        int redo = 0;

        bus_for_each_dev(&ccw_bus_type, NULL, &redo, recovery_check);
        if (redo) {
                spin_lock_irq(&recovery_lock);
                if (!timer_pending(&recovery_timer)) {
                        if (recovery_phase < ARRAY_SIZE(recovery_delay) - 1)
                                recovery_phase++;
                        mod_timer(&recovery_timer, jiffies +
                                  recovery_delay[recovery_phase] * HZ);
                }
                spin_unlock_irq(&recovery_lock);
        } else
                CIO_MSG_EVENT(4, "recovery: end\n");
}

static DECLARE_WORK(recovery_work, recovery_work_func);

static void recovery_func(unsigned long data)
{
        /*
         * We can't do our recovery in softirq context and it's not
         * performance critical, so we schedule it.
         */
        schedule_work(&recovery_work);
}

static void ccw_device_schedule_recovery(void)
{
        unsigned long flags;

        CIO_MSG_EVENT(4, "recovery: schedule\n");
        spin_lock_irqsave(&recovery_lock, flags);
        if (!timer_pending(&recovery_timer) || (recovery_phase != 0)) {
                recovery_phase = 0;
                mod_timer(&recovery_timer, jiffies + recovery_delay[0] * HZ);
        }
        spin_unlock_irqrestore(&recovery_lock, flags);
}

static void device_set_disconnected(struct ccw_device *cdev)
{
        if (!cdev)
                return;
        ccw_device_set_timeout(cdev, 0);
        cdev->private->flags.fake_irb = 0;
        cdev->private->state = DEV_STATE_DISCONNECTED;
        if (cdev->online)
                ccw_device_schedule_recovery();
}

static int io_subchannel_sch_event(struct subchannel *sch, int slow)
{
        int event, ret, disc;
        unsigned long flags;
        enum { NONE, UNREGISTER, UNREGISTER_PROBE, REPROBE } action;
        struct ccw_device *cdev;

        spin_lock_irqsave(sch->lock, flags);
        cdev = sch_get_cdev(sch);
        disc = device_is_disconnected(cdev);
        if (disc && slow) {
                /* Disconnected devices are evaluated directly only.*/
                spin_unlock_irqrestore(sch->lock, flags);
                return 0;
        }
        /* No interrupt after machine check - kill pending timers. */
        if (cdev)
                ccw_device_set_timeout(cdev, 0);
        if (!disc && !slow) {
                /* Non-disconnected devices are evaluated on the slow path. */
                spin_unlock_irqrestore(sch->lock, flags);
                return -EAGAIN;
        }
        event = io_subchannel_get_status(sch);
        CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, %s, %s path.\n",
                      sch->schid.ssid, sch->schid.sch_no, event,
                      disc ? "disconnected" : "normal",
                      slow ? "slow" : "fast");
        /* Analyze subchannel status. */
        action = NONE;
        switch (event) {
        case CIO_NO_PATH:
                if (disc) {
                        /* Check if paths have become available. */
                        action = REPROBE;
                        break;
                }
                /* fall through */
        case CIO_GONE:
                /* Prevent unwanted effects when opening lock. */
                cio_disable_subchannel(sch);
                device_set_disconnected(cdev);
                /* Ask driver what to do with device. */
                action = UNREGISTER;
                spin_unlock_irqrestore(sch->lock, flags);
                ret = io_subchannel_notify(sch, event);
                spin_lock_irqsave(sch->lock, flags);
                if (ret)
                        action = NONE;
                break;
        case CIO_REVALIDATE:
                /* Device will be removed, so no notify necessary. */
                if (disc)
                        /* Reprobe because immediate unregister might block. */
                        action = REPROBE;
                else
                        action = UNREGISTER_PROBE;
                break;
        case CIO_OPER:
                if (disc)
                        /* Get device operational again. */
                        action = REPROBE;
                break;
        }
        /* Perform action. */
        ret = 0;
        switch (action) {
        case UNREGISTER:
        case UNREGISTER_PROBE:
                /* Unregister device (will use subchannel lock). */
                spin_unlock_irqrestore(sch->lock, flags);
                css_sch_device_unregister(sch);
                spin_lock_irqsave(sch->lock, flags);

                /* Reset intparm to zeroes. */
                sch->schib.pmcw.intparm = 0;
                cio_modify(sch);
                break;
        case REPROBE:
                ccw_device_trigger_reprobe(cdev);
                break;
        default:
                break;
        }
        spin_unlock_irqrestore(sch->lock, flags);
        /* Probe if necessary. */
        if (action == UNREGISTER_PROBE)
                ret = css_probe_device(sch->schid);

        return ret;
}

#ifdef CONFIG_CCW_CONSOLE
static struct ccw_device console_cdev;
static struct ccw_device_private console_private;
static int console_cdev_in_use;

static DEFINE_SPINLOCK(ccw_console_lock);

spinlock_t * cio_get_console_lock(void)
{
        return &ccw_console_lock;
}

static int ccw_device_console_enable(struct ccw_device *cdev,
                                     struct subchannel *sch)
{
        int rc;

        /* Attach subchannel private data. */
        sch->private = cio_get_console_priv();
        memset(sch->private, 0, sizeof(struct io_subchannel_private));
        io_subchannel_init_fields(sch);
        sch->driver = &io_subchannel_driver;
        /* Initialize the ccw_device structure. */
        cdev->dev.parent= &sch->dev;
        rc = io_subchannel_recog(cdev, sch);
        if (rc)
                return rc;

        /* Now wait for the async. recognition to come to an end. */
        spin_lock_irq(cdev->ccwlock);
        while (!dev_fsm_final_state(cdev))
                wait_cons_dev();
        rc = -EIO;
        if (cdev->private->state != DEV_STATE_OFFLINE)
                goto out_unlock;
        ccw_device_online(cdev);
        while (!dev_fsm_final_state(cdev))
                wait_cons_dev();
        if (cdev->private->state != DEV_STATE_ONLINE)
                goto out_unlock;
        rc = 0;
out_unlock:
        spin_unlock_irq(cdev->ccwlock);
        return 0;
}

struct ccw_device *
ccw_device_probe_console(void)
{
        struct subchannel *sch;
        int ret;

        if (xchg(&console_cdev_in_use, 1) != 0)
                return ERR_PTR(-EBUSY);
        sch = cio_probe_console();
        if (IS_ERR(sch)) {
                console_cdev_in_use = 0;
                return (void *) sch;
        }
        memset(&console_cdev, 0, sizeof(struct ccw_device));
        memset(&console_private, 0, sizeof(struct ccw_device_private));
        console_cdev.private = &console_private;
        console_private.cdev = &console_cdev;
        ret = ccw_device_console_enable(&console_cdev, sch);
        if (ret) {
                cio_release_console();
                console_cdev_in_use = 0;
                return ERR_PTR(ret);
        }
        console_cdev.online = 1;
        return &console_cdev;
}
#endif

/*
 * get ccw_device matching the busid, but only if owned by cdrv
 */
static int
__ccwdev_check_busid(struct device *dev, void *id)
{
        char *bus_id;

        bus_id = id;

        return (strncmp(bus_id, dev->bus_id, BUS_ID_SIZE) == 0);
}


/**
 * get_ccwdev_by_busid() - obtain device from a bus id
 * @cdrv: driver the device is owned by
 * @bus_id: bus id of the device to be searched
 *
 * This function searches all devices owned by @cdrv for a device with a bus
 * id matching @bus_id.
 * Returns:
 *  If a match is found, its reference count of the found device is increased
 *  and it is returned; else %NULL is returned.
 */
struct ccw_device *get_ccwdev_by_busid(struct ccw_driver *cdrv,
                                       const char *bus_id)
{
        struct device *dev;
        struct device_driver *drv;

        drv = get_driver(&cdrv->driver);
        if (!drv)
                return NULL;

        dev = driver_find_device(drv, NULL, (void *)bus_id,
                                 __ccwdev_check_busid);
        put_driver(drv);

        return dev ? to_ccwdev(dev) : NULL;
}

/************************** device driver handling ************************/

/* This is the implementation of the ccw_driver class. The probe, remove
 * and release methods are initially very similar to the device_driver
 * implementations, with the difference that they have ccw_device
 * arguments.
 *
 * A ccw driver also contains the information that is needed for
 * device matching.
 */
static int
ccw_device_probe (struct device *dev)
{
        struct ccw_device *cdev = to_ccwdev(dev);
        struct ccw_driver *cdrv = to_ccwdrv(dev->driver);
        int ret;

        cdev->drv = cdrv; /* to let the driver call _set_online */

        ret = cdrv->probe ? cdrv->probe(cdev) : -ENODEV;

        if (ret) {
                cdev->drv = NULL;
                return ret;
        }

        return 0;
}

static int
ccw_device_remove (struct device *dev)
{
        struct ccw_device *cdev = to_ccwdev(dev);
        struct ccw_driver *cdrv = cdev->drv;
        int ret;

        if (cdrv->remove)
                cdrv->remove(cdev);
        if (cdev->online) {
                cdev->online = 0;
                spin_lock_irq(cdev->ccwlock);
                ret = ccw_device_offline(cdev);
                spin_unlock_irq(cdev->ccwlock);
                if (ret == 0)
                        wait_event(cdev->private->wait_q,
                                   dev_fsm_final_state(cdev));
                else
                        CIO_MSG_EVENT(0, "ccw_device_offline returned %d, "
                                      "device 0.%x.%04x\n",
                                      ret, cdev->private->dev_id.ssid,
                                      cdev->private->dev_id.devno);
        }
        ccw_device_set_timeout(cdev, 0);
        cdev->drv = NULL;
        return 0;
}

static void ccw_device_shutdown(struct device *dev)
{
        struct ccw_device *cdev;

        cdev = to_ccwdev(dev);
        if (cdev->drv && cdev->drv->shutdown)
                cdev->drv->shutdown(cdev);
        disable_cmf(cdev);
}

struct bus_type ccw_bus_type = {
        .name   = "ccw",
        .match  = ccw_bus_match,
        .uevent = ccw_uevent,
        .probe  = ccw_device_probe,
        .remove = ccw_device_remove,
        .shutdown = ccw_device_shutdown,
};

/**
 * ccw_driver_register() - register a ccw driver
 * @cdriver: driver to be registered
 *
 * This function is mainly a wrapper around driver_register().
 * Returns:
 *   %0 on success and a negative error value on failure.
 */
int ccw_driver_register(struct ccw_driver *cdriver)
{
        struct device_driver *drv = &cdriver->driver;

        drv->bus = &ccw_bus_type;
        drv->name = cdriver->name;
        drv->owner = cdriver->owner;

        return driver_register(drv);
}

/**
 * ccw_driver_unregister() - deregister a ccw driver
 * @cdriver: driver to be deregistered
 *
 * This function is mainly a wrapper around driver_unregister().
 */
void ccw_driver_unregister(struct ccw_driver *cdriver)
{
        driver_unregister(&cdriver->driver);
}

/* Helper func for qdio. */
struct subchannel_id
ccw_device_get_subchannel_id(struct ccw_device *cdev)
{
        struct subchannel *sch;

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

MODULE_LICENSE("GPL");
EXPORT_SYMBOL(ccw_device_set_online);
EXPORT_SYMBOL(ccw_device_set_offline);
EXPORT_SYMBOL(ccw_driver_register);
EXPORT_SYMBOL(ccw_driver_unregister);
EXPORT_SYMBOL(get_ccwdev_by_busid);
EXPORT_SYMBOL(ccw_bus_type);
EXPORT_SYMBOL(ccw_device_work);
EXPORT_SYMBOL(ccw_device_notify_work);
EXPORT_SYMBOL_GPL(ccw_device_get_subchannel_id);