device.c

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/*
 *  bus driver for ccw devices
 *
 *    Copyright IBM Corp. 2002, 2008
 *    Author(s): Arnd Bergmann ([email protected])
 *       Cornelia Huck ([email protected])
 *       Martin Schwidefsky ([email protected])
 */

#define KMSG_COMPONENT "cio"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#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 <linux/kernel_stat.h>

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

#include "chp.h"
#include "cio.h"
#include "cio_debug.h"
#include "css.h"
#include "device.h"
#include "ioasm.h"
#include "io_sch.h"
#include "blacklist.h"
#include "chsc.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;
}

static 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 *, struct chp_link *,
                   int);
static void recovery_func(unsigned long data);
wait_queue_head_t ccw_device_init_wq;
atomic_t ccw_device_init_count;

static struct css_device_id io_subchannel_ids[] = {
    { .match_flags = 0x1, .type = SUBCHANNEL_TYPE_IO, },
    { /* end of list */ },
};
MODULE_DEVICE_TABLE(css, io_subchannel_ids);

static int io_subchannel_prepare(struct subchannel *sch)
{
    struct ccw_device *cdev;
    /*
     * Don't allow suspend while a ccw device registration
     * is still outstanding.
     */
    cdev = sch_get_cdev(sch);
    if (cdev && !device_is_registered(&cdev->dev))
        return -EAGAIN;
    return 0;
}

static int io_subchannel_settle(void)
{
    int ret;

    ret = wait_event_interruptible(ccw_device_init_wq,
                atomic_read(&ccw_device_init_count) == 0);
    if (ret)
        return -EINTR;
    flush_workqueue(cio_work_q);
    return 0;
}

static struct css_driver io_subchannel_driver = {
    .drv = {
        .owner = THIS_MODULE,
        .name = "io_subchannel",
    },
    .subchannel_type = io_subchannel_ids,
    .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,
    .prepare = io_subchannel_prepare,
    .settle = io_subchannel_settle,
};

int __init io_subchannel_init(void)
{
    int ret;

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

    ret = bus_register(&ccw_bus_type);
    if (ret)
        return ret;
    ret = css_driver_register(&io_subchannel_driver);
    if (ret)
        bus_unregister(&ccw_bus_type);

    return ret;
}


/************************ 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 (device_is_registered(&cdev->dev)) {
        /* Undo device_add(). */
        device_del(&cdev->dev);
    }
    if (cdev->private->flags.initialized) {
        cdev->private->flags.initialized = 0;
        /* Release reference from device_initialize(). */
        put_device(&cdev->dev);
    }
}

static void io_subchannel_quiesce(struct subchannel *);

int ccw_device_set_offline(struct ccw_device *cdev)
{
    struct subchannel *sch;
    int ret, state;

    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);
    sch = to_subchannel(cdev->dev.parent);
    /* Wait until a final state or DISCONNECTED is reached */
    while (!dev_fsm_final_state(cdev) &&
           cdev->private->state != DEV_STATE_DISCONNECTED) {
        spin_unlock_irq(cdev->ccwlock);
        wait_event(cdev->private->wait_q, (dev_fsm_final_state(cdev) ||
               cdev->private->state == DEV_STATE_DISCONNECTED));
        spin_lock_irq(cdev->ccwlock);
    }
    do {
        ret = ccw_device_offline(cdev);
        if (!ret)
            break;
        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);
        if (ret != -EBUSY)
            goto error;
        state = cdev->private->state;
        spin_unlock_irq(cdev->ccwlock);
        io_subchannel_quiesce(sch);
        spin_lock_irq(cdev->ccwlock);
        cdev->private->state = state;
    } while (ret == -EBUSY);
    spin_unlock_irq(cdev->ccwlock);
    wait_event(cdev->private->wait_q, (dev_fsm_final_state(cdev) ||
           cdev->private->state == DEV_STATE_DISCONNECTED));
    /* Inform the user if set offline failed. */
    if (cdev->private->state == DEV_STATE_BOXED) {
        pr_warning("%s: The device entered boxed state while "
               "being set offline\n", dev_name(&cdev->dev));
    } else if (cdev->private->state == DEV_STATE_NOT_OPER) {
        pr_warning("%s: The device stopped operating while "
               "being set offline\n", dev_name(&cdev->dev));
    }
    /* Give up reference from ccw_device_set_online(). */
    put_device(&cdev->dev);
    return 0;

error:
    cdev->private->state = DEV_STATE_OFFLINE;
    dev_fsm_event(cdev, DEV_EVENT_NOTOPER);
    spin_unlock_irq(cdev->ccwlock);
    /* Give up reference from ccw_device_set_online(). */
    put_device(&cdev->dev);
    return -ENODEV;
}

int ccw_device_set_online(struct ccw_device *cdev)
{
    int ret;
    int ret2;

    if (!cdev)
        return -ENODEV;
    if (cdev->online || !cdev->drv)
        return -EINVAL;
    /* Hold on to an extra reference while device is online. */
    if (!get_device(&cdev->dev))
        return -ENODEV;

    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);
        /* Give up online reference since onlining failed. */
        put_device(&cdev->dev);
        return ret;
    }
    spin_lock_irq(cdev->ccwlock);
    /* Check if online processing was successful */
    if ((cdev->private->state != DEV_STATE_ONLINE) &&
        (cdev->private->state != DEV_STATE_W4SENSE)) {
        spin_unlock_irq(cdev->ccwlock);
        /* Inform the user that set online failed. */
        if (cdev->private->state == DEV_STATE_BOXED) {
            pr_warning("%s: Setting the device online failed "
                   "because it is boxed\n",
                   dev_name(&cdev->dev));
        } else if (cdev->private->state == DEV_STATE_NOT_OPER) {
            pr_warning("%s: Setting the device online failed "
                   "because it is not operational\n",
                   dev_name(&cdev->dev));
        }
        /* Give up online reference since onlining failed. */
        put_device(&cdev->dev);
        return -ENODEV;
    }
    spin_unlock_irq(cdev->ccwlock);
    if (cdev->drv->set_online)
        ret = cdev->drv->set_online(cdev);
    if (ret)
        goto rollback;
    cdev->online = 1;
    return 0;

rollback:
    spin_lock_irq(cdev->ccwlock);
    /* Wait until a final state or DISCONNECTED is reached */
    while (!dev_fsm_final_state(cdev) &&
           cdev->private->state != DEV_STATE_DISCONNECTED) {
        spin_unlock_irq(cdev->ccwlock);
        wait_event(cdev->private->wait_q, (dev_fsm_final_state(cdev) ||
               cdev->private->state == DEV_STATE_DISCONNECTED));
        spin_lock_irq(cdev->ccwlock);
    }
    ret2 = ccw_device_offline(cdev);
    if (ret2)
        goto error;
    spin_unlock_irq(cdev->ccwlock);
    wait_event(cdev->private->wait_q, (dev_fsm_final_state(cdev) ||
           cdev->private->state == DEV_STATE_DISCONNECTED));
    /* Give up online reference since onlining failed. */
    put_device(&cdev->dev);
    return ret;

error:
    CIO_MSG_EVENT(0, "rollback ccw_device_offline returned %d, "
              "device 0.%x.%04x\n",
              ret2, cdev->private->dev_id.ssid,
              cdev->private->dev_id.devno);
    cdev->private->state = DEV_STATE_OFFLINE;
    spin_unlock_irq(cdev->ccwlock);
    /* Give up online reference since onlining failed. */
    put_device(&cdev->dev);
    return ret;
}

static int online_store_handle_offline(struct ccw_device *cdev)
{
    if (cdev->private->state == DEV_STATE_DISCONNECTED) {
        spin_lock_irq(cdev->ccwlock);
        ccw_device_sched_todo(cdev, CDEV_TODO_UNREG_EVAL);
        spin_unlock_irq(cdev->ccwlock);
        return 0;
    }
    if (cdev->drv && cdev->drv->set_offline)
        return ccw_device_set_offline(cdev);
    return -EINVAL;
}

static int online_store_recog_and_online(struct ccw_device *cdev)
{
    /* Do device recognition, if needed. */
    if (cdev->private->state == DEV_STATE_BOXED) {
        spin_lock_irq(cdev->ccwlock);
        ccw_device_recognition(cdev);
        spin_unlock_irq(cdev->ccwlock);
        wait_event(cdev->private->wait_q,
               cdev->private->flags.recog_done);
        if (cdev->private->state != DEV_STATE_OFFLINE)
            /* recognition failed */
            return -EAGAIN;
    }
    if (cdev->drv && cdev->drv->set_online)
        return ccw_device_set_online(cdev);
    return -EINVAL;
}

static int online_store_handle_online(struct ccw_device *cdev, int force)
{
    int ret;

    ret = online_store_recog_and_online(cdev);
    if (ret && !force)
        return ret;
    if (force && cdev->private->state == DEV_STATE_BOXED) {
        ret = ccw_device_stlck(cdev);
        if (ret)
            return ret;
        if (cdev->id.cu_type == 0)
            cdev->private->state = DEV_STATE_NOT_OPER;
        ret = online_store_recog_and_online(cdev);
        if (ret)
            return ret;
    }
    return 0;
}

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;

    /* Prevent conflict between multiple on-/offline processing requests. */
    if (atomic_cmpxchg(&cdev->private->onoff, 0, 1) != 0)
        return -EAGAIN;
    /* Prevent conflict between internal I/Os and on-/offline processing. */
    if (!dev_fsm_final_state(cdev) &&
        cdev->private->state != DEV_STATE_DISCONNECTED) {
        ret = -EAGAIN;
        goto out_onoff;
    }
    /* Prevent conflict between pending work and on-/offline processing.*/
    if (work_pending(&cdev->private->todo_work)) {
        ret = -EAGAIN;
        goto out_onoff;
    }

    if (cdev->drv && !try_module_get(cdev->drv->driver.owner)) {
        ret = -EINVAL;
        goto out_onoff;
    }
    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:
        ret = online_store_handle_offline(cdev);
        break;
    case 1:
        ret = online_store_handle_online(cdev, force);
        break;
    default:
        ret = -EINVAL;
    }
out:
    if (cdev->drv)
        module_put(cdev->drv->driver.owner);
out_onoff:
    atomic_set(&cdev->private->onoff, 0);
    return (ret < 0) ? ret : count;
}

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 ssize_t
initiate_logging(struct device *dev, struct device_attribute *attr,
         const char *buf, size_t count)
{
    struct subchannel *sch = to_subchannel(dev);
    int rc;

    rc = chsc_siosl(sch->schid);
    if (rc < 0) {
        pr_warning("Logging for subchannel 0.%x.%04x failed with "
               "errno=%d\n",
               sch->schid.ssid, sch->schid.sch_no, rc);
        return rc;
    }
    pr_notice("Logging for subchannel 0.%x.%04x was triggered\n",
          sch->schid.ssid, sch->schid.sch_no);
    return count;
}

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 DEVICE_ATTR(logging, 0200, NULL, initiate_logging);

static struct attribute *io_subchannel_attrs[] = {
    &dev_attr_chpids.attr,
    &dev_attr_pimpampom.attr,
    &dev_attr_logging.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 const 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;
    ret = dev_set_name(&cdev->dev, "0.%x.%04x", cdev->private->dev_id.ssid,
               cdev->private->dev_id.devno);
    if (ret)
        return ret;
    return device_add(dev);
}

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

    return ccw_dev_id_is_equal(&cdev->private->dev_id, dev_id);
}

struct ccw_device *get_ccwdev_by_dev_id(struct ccw_dev_id *dev_id)
{
    struct device *dev;

    dev = bus_find_device(&ccw_bus_type, NULL, dev_id, match_dev_id);

    return dev ? to_ccwdev(dev) : NULL;
}
EXPORT_SYMBOL_GPL(get_ccwdev_by_dev_id);

static void ccw_device_do_unbind_bind(struct ccw_device *cdev)
{
    int ret;

    if (device_is_registered(&cdev->dev)) {
        device_release_driver(&cdev->dev);
        ret = device_attach(&cdev->dev);
        WARN_ON(ret == -ENODEV);
    }
}

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

    cdev = to_ccwdev(dev);
    /* Release reference of parent subchannel. */
    put_device(cdev->dev.parent);
    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 void ccw_device_todo(struct work_struct *work);

static int io_subchannel_initialize_dev(struct subchannel *sch,
                    struct ccw_device *cdev)
{
    cdev->private->cdev = cdev;
    cdev->private->int_class = IOINT_CIO;
    atomic_set(&cdev->private->onoff, 0);
    cdev->dev.parent = &sch->dev;
    cdev->dev.release = ccw_device_release;
    INIT_WORK(&cdev->private->todo_work, ccw_device_todo);
    cdev->dev.groups = ccwdev_attr_groups;
    /* Do first half of device_register. */
    device_initialize(&cdev->dev);
    if (!get_device(&sch->dev)) {
        /* Release reference from device_initialize(). */
        put_device(&cdev->dev);
        return -ENODEV;
    }
    cdev->private->flags.initialized = 1;
    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)
            cdev = ERR_PTR(ret);
    }
    return cdev;
}

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

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;
    }
    /* Start recognition for the new ccw device. */
    io_subchannel_recog(cdev, sch);
}

/*
 * Register recognized device.
 */
static void io_subchannel_register(struct ccw_device *cdev)
{
    struct subchannel *sch;
    int ret, adjust_init_count = 1;
    unsigned long flags;

    sch = to_subchannel(cdev->dev.parent);
    /*
     * Check if subchannel is still registered. It may have become
     * unregistered if a machine check hit us after finishing
     * device recognition but before the register work could be
     * queued.
     */
    if (!device_is_registered(&sch->dev))
        goto out_err;
    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 (device_is_registered(&cdev->dev)) {
        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);
        }
        adjust_init_count = 0;
        goto out;
    }
    /*
     * Now we know this subchannel will stay, we can throw
     * our delayed uevent.
     */
    dev_set_uevent_suppress(&sch->dev, 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);
        spin_lock_irqsave(sch->lock, flags);
        sch_set_cdev(sch, NULL);
        spin_unlock_irqrestore(sch->lock, flags);
        /* Release initial device reference. */
        put_device(&cdev->dev);
        goto out_err;
    }
out:
    cdev->private->flags.recog_done = 1;
    wake_up(&cdev->private->wait_q);
out_err:
    if (adjust_init_count && atomic_dec_and_test(&ccw_device_init_count))
        wake_up(&ccw_device_init_wq);
}

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

    /* Get subchannel reference for local processing. */
    if (!get_device(cdev->dev.parent))
        return;
    sch = to_subchannel(cdev->dev.parent);
    css_sch_device_unregister(sch);
    /* Release subchannel reference for local processing. */
    put_device(&sch->dev);
}

/*
 * subchannel recognition done. Called from the state machine.
 */
void
io_subchannel_recog_done(struct ccw_device *cdev)
{
    if (css_init_done == 0) {
        cdev->private->flags.recog_done = 1;
        return;
    }
    switch (cdev->private->state) {
    case DEV_STATE_BOXED:
        /* Device did not respond in time. */
    case DEV_STATE_NOT_OPER:
        cdev->private->flags.recog_done = 1;
        /* Remove device found not operational. */
        ccw_device_sched_todo(cdev, CDEV_TODO_UNREG);
        if (atomic_dec_and_test(&ccw_device_init_count))
            wake_up(&ccw_device_init_wq);
        break;
    case DEV_STATE_OFFLINE:
        /* 
         * We can't register the device in interrupt context so
         * we schedule a work item.
         */
        ccw_device_sched_todo(cdev, CDEV_TODO_REGISTER);
        break;
    }
}

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

    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);

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

    /* Start async. device sensing. */
    spin_lock_irq(sch->lock);
    sch_set_cdev(sch, cdev);
    ccw_device_recognition(cdev);
    spin_unlock_irq(sch->lock);
}

static int ccw_device_move_to_sch(struct ccw_device *cdev,
                  struct subchannel *sch)
{
    struct subchannel *old_sch;
    int rc, old_enabled = 0;

    old_sch = to_subchannel(cdev->dev.parent);
    /* Obtain child reference for new parent. */
    if (!get_device(&sch->dev))
        return -ENODEV;

    if (!sch_is_pseudo_sch(old_sch)) {
        spin_lock_irq(old_sch->lock);
        old_enabled = old_sch->schib.pmcw.ena;
        rc = 0;
        if (old_enabled)
            rc = cio_disable_subchannel(old_sch);
        spin_unlock_irq(old_sch->lock);
        if (rc == -EBUSY) {
            /* Release child reference for new parent. */
            put_device(&sch->dev);
            return rc;
        }
    }

    mutex_lock(&sch->reg_mutex);
    rc = device_move(&cdev->dev, &sch->dev, DPM_ORDER_PARENT_BEFORE_DEV);
    mutex_unlock(&sch->reg_mutex);
    if (rc) {
        CIO_MSG_EVENT(0, "device_move(0.%x.%04x,0.%x.%04x)=%d\n",
                  cdev->private->dev_id.ssid,
                  cdev->private->dev_id.devno, sch->schid.ssid,
                  sch->schib.pmcw.dev, rc);
        if (old_enabled) {
            /* Try to reenable the old subchannel. */
            spin_lock_irq(old_sch->lock);
            cio_enable_subchannel(old_sch, (u32)(addr_t)old_sch);
            spin_unlock_irq(old_sch->lock);
        }
        /* Release child reference for new parent. */
        put_device(&sch->dev);
        return rc;
    }
    /* Clean up old subchannel. */
    if (!sch_is_pseudo_sch(old_sch)) {
        spin_lock_irq(old_sch->lock);
        sch_set_cdev(old_sch, NULL);
        spin_unlock_irq(old_sch->lock);
        css_schedule_eval(old_sch->schid);
    }
    /* Release child reference for old parent. */
    put_device(&old_sch->dev);
    /* Initialize new subchannel. */
    spin_lock_irq(sch->lock);
    cdev->private->schid = sch->schid;
    cdev->ccwlock = sch->lock;
    if (!sch_is_pseudo_sch(sch))
        sch_set_cdev(sch, cdev);
    spin_unlock_irq(sch->lock);
    if (!sch_is_pseudo_sch(sch))
        css_update_ssd_info(sch);
    return 0;
}

static int ccw_device_move_to_orph(struct ccw_device *cdev)
{
    struct subchannel *sch = to_subchannel(cdev->dev.parent);
    struct channel_subsystem *css = to_css(sch->dev.parent);

    return ccw_device_move_to_sch(cdev, css->pseudo_subchannel);
}

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

    cdev = sch_get_cdev(sch);

    CIO_TRACE_EVENT(6, "IRQ");
    CIO_TRACE_EVENT(6, dev_name(&sch->dev));
    if (cdev)
        dev_fsm_event(cdev, DEV_EVENT_INTERRUPT);
    else
        kstat_cpu(smp_processor_id()).irqs[IOINT_CIO]++;
}

void io_subchannel_init_config(struct subchannel *sch)
{
    memset(&sch->config, 0, sizeof(sch->config));
    sch->config.csense = 1;
}

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) ? CONSOLE_ISC : IO_SCH_ISC;

    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);

    io_subchannel_init_config(sch);
}

/*
 * Note: We always return 0 so that we bind to the device even on error.
 * This is needed so that our remove function is called on unregister.
 */
static int io_subchannel_probe(struct subchannel *sch)
{
    struct io_subchannel_private *io_priv;
    struct ccw_device *cdev;
    int rc;

    if (cio_is_console(sch->schid)) {
        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);
        /*
         * The console subchannel already has an associated ccw_device.
         * Throw the delayed uevent for the subchannel, register
         * the ccw_device and exit.
         */
        dev_set_uevent_suppress(&sch->dev, 0);
        kobject_uevent(&sch->dev.kobj, KOBJ_ADD);
        cdev = sch_get_cdev(sch);
        cdev->dev.groups = ccwdev_attr_groups;
        device_initialize(&cdev->dev);
        cdev->private->flags.initialized = 1;
        ccw_device_register(cdev);
        /*
         * Check if the device is already online. If it is
         * the reference count needs to be corrected since we
         * didn't obtain a reference in ccw_device_set_online.
         */
        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);
    rc = cio_commit_config(sch);
    if (rc)
        goto out_schedule;
    rc = sysfs_create_group(&sch->dev.kobj,
                &io_subchannel_attr_group);
    if (rc)
        goto out_schedule;
    /* Allocate I/O subchannel private data. */
    io_priv = kzalloc(sizeof(*io_priv), GFP_KERNEL | GFP_DMA);
    if (!io_priv)
        goto out_schedule;

    set_io_private(sch, io_priv);
    css_schedule_eval(sch->schid);
    return 0;

out_schedule:
    spin_lock_irq(sch->lock);
    css_sched_sch_todo(sch, SCH_TODO_UNREG);
    spin_unlock_irq(sch->lock);
    return 0;
}

static int
io_subchannel_remove (struct subchannel *sch)
{
    struct io_subchannel_private *io_priv = to_io_private(sch);
    struct ccw_device *cdev;

    cdev = sch_get_cdev(sch);
    if (!cdev)
        goto out_free;
    io_subchannel_quiesce(sch);
    /* Set ccw device to not operational and drop reference. */
    spin_lock_irq(cdev->ccwlock);
    sch_set_cdev(sch, NULL);
    set_io_private(sch, NULL);
    cdev->private->state = DEV_STATE_NOT_OPER;
    spin_unlock_irq(cdev->ccwlock);
    ccw_device_unregister(cdev);
out_free:
    kfree(io_priv);
    sysfs_remove_group(&sch->dev.kobj, &io_subchannel_attr_group);
    return 0;
}

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

    cdev = sch_get_cdev(sch);
    if (!cdev)
        return;
    if (cio_update_schib(sch))
        goto err;
    /* Check for I/O on path. */
    if (scsw_actl(&sch->schib.scsw) == 0 || sch->schib.pmcw.lpum != mask)
        goto out;
    if (cdev->private->state == DEV_STATE_ONLINE) {
        ccw_device_kill_io(cdev);
        goto out;
    }
    if (cio_clear(sch))
        goto err;
out:
    /* Trigger path verification. */
    dev_fsm_event(cdev, DEV_EVENT_VERIFY);
    return;

err:
    dev_fsm_event(cdev, DEV_EVENT_NOTOPER);
}

static int io_subchannel_chp_event(struct subchannel *sch,
                   struct chp_link *link, int event)
{
    struct ccw_device *cdev = sch_get_cdev(sch);
    int mask;

    mask = chp_ssd_get_mask(&sch->ssd_info, link);
    if (!mask)
        return 0;
    switch (event) {
    case CHP_VARY_OFF:
        sch->opm &= ~mask;
        sch->lpm &= ~mask;
        if (cdev)
            cdev->private->path_gone_mask |= mask;
        io_subchannel_terminate_path(sch, mask);
        break;
    case CHP_VARY_ON:
        sch->opm |= mask;
        sch->lpm |= mask;
        if (cdev)
            cdev->private->path_new_mask |= mask;
        io_subchannel_verify(sch);
        break;
    case CHP_OFFLINE:
        if (cio_update_schib(sch))
            return -ENODEV;
        if (cdev)
            cdev->private->path_gone_mask |= mask;
        io_subchannel_terminate_path(sch, mask);
        break;
    case CHP_ONLINE:
        if (cio_update_schib(sch))
            return -ENODEV;
        sch->lpm |= mask & sch->opm;
        if (cdev)
            cdev->private->path_new_mask |= mask;
        io_subchannel_verify(sch);
        break;
    }
    return 0;
}

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

    spin_lock_irq(sch->lock);
    cdev = sch_get_cdev(sch);
    if (cio_is_console(sch->schid))
        goto out_unlock;
    if (!sch->schib.pmcw.ena)
        goto out_unlock;
    ret = cio_disable_subchannel(sch);
    if (ret != -EBUSY)
        goto out_unlock;
    if (cdev->handler)
        cdev->handler(cdev, cdev->private->intparm, ERR_PTR(-EIO));
    while (ret == -EBUSY) {
        cdev->private->state = DEV_STATE_QUIESCE;
        cdev->private->iretry = 255;
        ret = ccw_device_cancel_halt_clear(cdev);
        if (ret == -EBUSY) {
            ccw_device_set_timeout(cdev, HZ/10);
            spin_unlock_irq(sch->lock);
            wait_event(cdev->private->wait_q,
                   cdev->private->state != DEV_STATE_QUIESCE);
            spin_lock_irq(sch->lock);
        }
        ret = cio_disable_subchannel(sch);
    }
out_unlock:
    spin_unlock_irq(sch->lock);
}

static void io_subchannel_shutdown(struct subchannel *sch)
{
    io_subchannel_quiesce(sch);
}

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 int purge_fn(struct device *dev, void *data)
{
    struct ccw_device *cdev = to_ccwdev(dev);
    struct ccw_dev_id *id = &cdev->private->dev_id;

    spin_lock_irq(cdev->ccwlock);
    if (is_blacklisted(id->ssid, id->devno) &&
        (cdev->private->state == DEV_STATE_OFFLINE) &&
        (atomic_cmpxchg(&cdev->private->onoff, 0, 1) == 0)) {
        CIO_MSG_EVENT(3, "ccw: purging 0.%x.%04x\n", id->ssid,
                  id->devno);
        ccw_device_sched_todo(cdev, CDEV_TODO_UNREG);
        atomic_set(&cdev->private->onoff, 0);
    }
    spin_unlock_irq(cdev->ccwlock);
    /* Abort loop in case of pending signal. */
    if (signal_pending(current))
        return -EINTR;

    return 0;
}

int ccw_purge_blacklisted(void)
{
    CIO_MSG_EVENT(2, "ccw: purging blacklisted devices\n");
    bus_for_each_dev(&ccw_bus_type, NULL, NULL, purge_fn);
    return 0;
}

void ccw_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();
}

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

    CIO_TRACE_EVENT(2, "notoper");
    CIO_TRACE_EVENT(2, dev_name(&sch->dev));
    ccw_device_set_timeout(cdev, 0);
    cio_disable_subchannel(sch);
    cdev->private->state = DEV_STATE_NOT_OPER;
}

enum io_sch_action {
    IO_SCH_UNREG,
    IO_SCH_ORPH_UNREG,
    IO_SCH_ATTACH,
    IO_SCH_UNREG_ATTACH,
    IO_SCH_ORPH_ATTACH,
    IO_SCH_REPROBE,
    IO_SCH_VERIFY,
    IO_SCH_DISC,
    IO_SCH_NOP,
};

static enum io_sch_action sch_get_action(struct subchannel *sch)
{
    struct ccw_device *cdev;

    cdev = sch_get_cdev(sch);
    if (cio_update_schib(sch)) {
        /* Not operational. */
        if (!cdev)
            return IO_SCH_UNREG;
        if (ccw_device_notify(cdev, CIO_GONE) != NOTIFY_OK)
            return IO_SCH_UNREG;
        return IO_SCH_ORPH_UNREG;
    }
    /* Operational. */
    if (!cdev)
        return IO_SCH_ATTACH;
    if (sch->schib.pmcw.dev != cdev->private->dev_id.devno) {
        if (ccw_device_notify(cdev, CIO_GONE) != NOTIFY_OK)
            return IO_SCH_UNREG_ATTACH;
        return IO_SCH_ORPH_ATTACH;
    }
    if ((sch->schib.pmcw.pam & sch->opm) == 0) {
        if (ccw_device_notify(cdev, CIO_NO_PATH) != NOTIFY_OK)
            return IO_SCH_UNREG;
        return IO_SCH_DISC;
    }
    if (device_is_disconnected(cdev))
        return IO_SCH_REPROBE;
    if (cdev->online && !cdev->private->flags.resuming)
        return IO_SCH_VERIFY;
    if (cdev->private->state == DEV_STATE_NOT_OPER)
        return IO_SCH_UNREG_ATTACH;
    return IO_SCH_NOP;
}

static int io_subchannel_sch_event(struct subchannel *sch, int process)
{
    unsigned long flags;
    struct ccw_device *cdev;
    struct ccw_dev_id dev_id;
    enum io_sch_action action;
    int rc = -EAGAIN;

    spin_lock_irqsave(sch->lock, flags);
    if (!device_is_registered(&sch->dev))
        goto out_unlock;
    if (work_pending(&sch->todo_work))
        goto out_unlock;
    cdev = sch_get_cdev(sch);
    if (cdev && work_pending(&cdev->private->todo_work))
        goto out_unlock;
    action = sch_get_action(sch);
    CIO_MSG_EVENT(2, "event: sch 0.%x.%04x, process=%d, action=%d\n",
              sch->schid.ssid, sch->schid.sch_no, process,
              action);
    /* Perform immediate actions while holding the lock. */
    switch (action) {
    case IO_SCH_REPROBE:
        /* Trigger device recognition. */
        ccw_device_trigger_reprobe(cdev);
        rc = 0;
        goto out_unlock;
    case IO_SCH_VERIFY:
        /* Trigger path verification. */
        io_subchannel_verify(sch);
        rc = 0;
        goto out_unlock;
    case IO_SCH_DISC:
        ccw_device_set_disconnected(cdev);
        rc = 0;
        goto out_unlock;
    case IO_SCH_ORPH_UNREG:
    case IO_SCH_ORPH_ATTACH:
        ccw_device_set_disconnected(cdev);
        break;
    case IO_SCH_UNREG_ATTACH:
    case IO_SCH_UNREG:
        if (!cdev)
            break;
        if (cdev->private->state == DEV_STATE_SENSE_ID) {
            /*
             * Note: delayed work triggered by this event
             * and repeated calls to sch_event are synchronized
             * by the above check for work_pending(cdev).
             */
            dev_fsm_event(cdev, DEV_EVENT_NOTOPER);
        } else
            ccw_device_set_notoper(cdev);
        break;
    case IO_SCH_NOP:
        rc = 0;
        goto out_unlock;
    default:
        break;
    }
    spin_unlock_irqrestore(sch->lock, flags);
    /* All other actions require process context. */
    if (!process)
        goto out;
    /* Handle attached ccw device. */
    switch (action) {
    case IO_SCH_ORPH_UNREG:
    case IO_SCH_ORPH_ATTACH:
        /* Move ccw device to orphanage. */
        rc = ccw_device_move_to_orph(cdev);
        if (rc)
            goto out;
        break;
    case IO_SCH_UNREG_ATTACH:
        spin_lock_irqsave(sch->lock, flags);
        if (cdev->private->flags.resuming) {
            /* Device will be handled later. */
            rc = 0;
            goto out_unlock;
        }
        sch_set_cdev(sch, NULL);
        spin_unlock_irqrestore(sch->lock, flags);
        /* Unregister ccw device. */
        ccw_device_unregister(cdev);
        break;
    default:
        break;
    }
    /* Handle subchannel. */
    switch (action) {
    case IO_SCH_ORPH_UNREG:
    case IO_SCH_UNREG:
        if (!cdev || !cdev->private->flags.resuming)
            css_sch_device_unregister(sch);
        break;
    case IO_SCH_ORPH_ATTACH:
    case IO_SCH_UNREG_ATTACH:
    case IO_SCH_ATTACH:
        dev_id.ssid = sch->schid.ssid;
        dev_id.devno = sch->schib.pmcw.dev;
        cdev = get_ccwdev_by_dev_id(&dev_id);
        if (!cdev) {
            sch_create_and_recog_new_device(sch);
            break;
        }
        rc = ccw_device_move_to_sch(cdev, sch);
        if (rc) {
            /* Release reference from get_ccwdev_by_dev_id() */
            put_device(&cdev->dev);
            goto out;
        }
        spin_lock_irqsave(sch->lock, flags);
        ccw_device_trigger_reprobe(cdev);
        spin_unlock_irqrestore(sch->lock, flags);
        /* Release reference from get_ccwdev_by_dev_id() */
        put_device(&cdev->dev);
        break;
    default:
        break;
    }
    return 0;

out_unlock:
    spin_unlock_irqrestore(sch->lock, flags);
out:
    return rc;
}

#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)
{
    struct io_subchannel_private *io_priv = cio_get_console_priv();
    int rc;

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

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;
    console_private.int_class = IOINT_CIO;
    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;
}

static int ccw_device_pm_restore(struct device *dev);

int ccw_device_force_console(void)
{
    if (!console_cdev_in_use)
        return -ENODEV;
    return ccw_device_pm_restore(&console_cdev.dev);
}
EXPORT_SYMBOL_GPL(ccw_device_force_console);
#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 (strcmp(bus_id, dev_name(dev)) == 0);
}


struct ccw_device *get_ccwdev_by_busid(struct ccw_driver *cdrv,
                       const char *bus_id)
{
    struct device *dev;

    dev = driver_find_device(&cdrv->driver, NULL, (void *)bus_id,
                 __ccwdev_check_busid);

    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 */
    /* Note: we interpret class 0 in this context as an uninitialized
     * field since it translates to a non-I/O interrupt class. */
    if (cdrv->int_class != 0)
        cdev->private->int_class = cdrv->int_class;
    else
        cdev->private->int_class = IOINT_CIO;

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

    if (ret) {
        cdev->drv = NULL;
        cdev->private->int_class = IOINT_CIO;
        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);
        /* Give up reference obtained in ccw_device_set_online(). */
        put_device(&cdev->dev);
    }
    ccw_device_set_timeout(cdev, 0);
    cdev->drv = NULL;
    cdev->private->int_class = IOINT_CIO;
    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);
}

static int ccw_device_pm_prepare(struct device *dev)
{
    struct ccw_device *cdev = to_ccwdev(dev);

    if (work_pending(&cdev->private->todo_work))
        return -EAGAIN;
    /* Fail while device is being set online/offline. */
    if (atomic_read(&cdev->private->onoff))
        return -EAGAIN;

    if (cdev->online && cdev->drv && cdev->drv->prepare)
        return cdev->drv->prepare(cdev);

    return 0;
}

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

    if (cdev->online && cdev->drv && cdev->drv->complete)
        cdev->drv->complete(cdev);
}

static int ccw_device_pm_freeze(struct device *dev)
{
    struct ccw_device *cdev = to_ccwdev(dev);
    struct subchannel *sch = to_subchannel(cdev->dev.parent);
    int ret, cm_enabled;

    /* Fail suspend while device is in transistional state. */
    if (!dev_fsm_final_state(cdev))
        return -EAGAIN;
    if (!cdev->online)
        return 0;
    if (cdev->drv && cdev->drv->freeze) {
        ret = cdev->drv->freeze(cdev);
        if (ret)
            return ret;
    }

    spin_lock_irq(sch->lock);
    cm_enabled = cdev->private->cmb != NULL;
    spin_unlock_irq(sch->lock);
    if (cm_enabled) {
        /* Don't have the css write on memory. */
        ret = ccw_set_cmf(cdev, 0);
        if (ret)
            return ret;
    }
    /* From here on, disallow device driver I/O. */
    spin_lock_irq(sch->lock);
    ret = cio_disable_subchannel(sch);
    spin_unlock_irq(sch->lock);

    return ret;
}

static int ccw_device_pm_thaw(struct device *dev)
{
    struct ccw_device *cdev = to_ccwdev(dev);
    struct subchannel *sch = to_subchannel(cdev->dev.parent);
    int ret, cm_enabled;

    if (!cdev->online)
        return 0;

    spin_lock_irq(sch->lock);
    /* Allow device driver I/O again. */
    ret = cio_enable_subchannel(sch, (u32)(addr_t)sch);
    cm_enabled = cdev->private->cmb != NULL;
    spin_unlock_irq(sch->lock);
    if (ret)
        return ret;

    if (cm_enabled) {
        ret = ccw_set_cmf(cdev, 1);
        if (ret)
            return ret;
    }

    if (cdev->drv && cdev->drv->thaw)
        ret = cdev->drv->thaw(cdev);

    return ret;
}

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

    spin_lock_irq(sch->lock);
    if (cio_is_console(sch->schid)) {
        cio_enable_subchannel(sch, (u32)(addr_t)sch);
        goto out_unlock;
    }
    /*
     * While we were sleeping, devices may have gone or become
     * available again. Kick re-detection.
     */
    cdev->private->flags.resuming = 1;
    cdev->private->path_new_mask = LPM_ANYPATH;
    css_sched_sch_todo(sch, SCH_TODO_EVAL);
    spin_unlock_irq(sch->lock);
    css_wait_for_slow_path();

    /* cdev may have been moved to a different subchannel. */
    sch = to_subchannel(cdev->dev.parent);
    spin_lock_irq(sch->lock);
    if (cdev->private->state != DEV_STATE_ONLINE &&
        cdev->private->state != DEV_STATE_OFFLINE)
        goto out_unlock;

    ccw_device_recognition(cdev);
    spin_unlock_irq(sch->lock);
    wait_event(cdev->private->wait_q, dev_fsm_final_state(cdev) ||
           cdev->private->state == DEV_STATE_DISCONNECTED);
    spin_lock_irq(sch->lock);

out_unlock:
    cdev->private->flags.resuming = 0;
    spin_unlock_irq(sch->lock);
}

static int resume_handle_boxed(struct ccw_device *cdev)
{
    cdev->private->state = DEV_STATE_BOXED;
    if (ccw_device_notify(cdev, CIO_BOXED) == NOTIFY_OK)
        return 0;
    ccw_device_sched_todo(cdev, CDEV_TODO_UNREG);
    return -ENODEV;
}

static int resume_handle_disc(struct ccw_device *cdev)
{
    cdev->private->state = DEV_STATE_DISCONNECTED;
    if (ccw_device_notify(cdev, CIO_GONE) == NOTIFY_OK)
        return 0;
    ccw_device_sched_todo(cdev, CDEV_TODO_UNREG);
    return -ENODEV;
}

static int ccw_device_pm_restore(struct device *dev)
{
    struct ccw_device *cdev = to_ccwdev(dev);
    struct subchannel *sch;
    int ret = 0;

    __ccw_device_pm_restore(cdev);
    sch = to_subchannel(cdev->dev.parent);
    spin_lock_irq(sch->lock);
    if (cio_is_console(sch->schid))
        goto out_restore;

    /* check recognition results */
    switch (cdev->private->state) {
    case DEV_STATE_OFFLINE:
    case DEV_STATE_ONLINE:
        cdev->private->flags.donotify = 0;
        break;
    case DEV_STATE_BOXED:
        ret = resume_handle_boxed(cdev);
        if (ret)
            goto out_unlock;
        goto out_restore;
    default:
        ret = resume_handle_disc(cdev);
        if (ret)
            goto out_unlock;
        goto out_restore;
    }
    /* check if the device type has changed */
    if (!ccw_device_test_sense_data(cdev)) {
        ccw_device_update_sense_data(cdev);
        ccw_device_sched_todo(cdev, CDEV_TODO_REBIND);
        ret = -ENODEV;
        goto out_unlock;
    }
    if (!cdev->online)
        goto out_unlock;

    if (ccw_device_online(cdev)) {
        ret = resume_handle_disc(cdev);
        if (ret)
            goto out_unlock;
        goto out_restore;
    }
    spin_unlock_irq(sch->lock);
    wait_event(cdev->private->wait_q, dev_fsm_final_state(cdev));
    spin_lock_irq(sch->lock);

    if (ccw_device_notify(cdev, CIO_OPER) == NOTIFY_BAD) {
        ccw_device_sched_todo(cdev, CDEV_TODO_UNREG);
        ret = -ENODEV;
        goto out_unlock;
    }

    /* reenable cmf, if needed */
    if (cdev->private->cmb) {
        spin_unlock_irq(sch->lock);
        ret = ccw_set_cmf(cdev, 1);
        spin_lock_irq(sch->lock);
        if (ret) {
            CIO_MSG_EVENT(2, "resume: cdev 0.%x.%04x: cmf failed "
                      "(rc=%d)\n", cdev->private->dev_id.ssid,
                      cdev->private->dev_id.devno, ret);
            ret = 0;
        }
    }

out_restore:
    spin_unlock_irq(sch->lock);
    if (cdev->online && cdev->drv && cdev->drv->restore)
        ret = cdev->drv->restore(cdev);
    return ret;

out_unlock:
    spin_unlock_irq(sch->lock);
    return ret;
}

static const struct dev_pm_ops ccw_pm_ops = {
    .prepare = ccw_device_pm_prepare,
    .complete = ccw_device_pm_complete,
    .freeze = ccw_device_pm_freeze,
    .thaw = ccw_device_pm_thaw,
    .restore = ccw_device_pm_restore,
};

static 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,
    .pm = &ccw_pm_ops,
};

int ccw_driver_register(struct ccw_driver *cdriver)
{
    struct device_driver *drv = &cdriver->driver;

    drv->bus = &ccw_bus_type;

    return driver_register(drv);
}

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;
}

static void ccw_device_todo(struct work_struct *work)
{
    struct ccw_device_private *priv;
    struct ccw_device *cdev;
    struct subchannel *sch;
    enum cdev_todo todo;

    priv = container_of(work, struct ccw_device_private, todo_work);
    cdev = priv->cdev;
    sch = to_subchannel(cdev->dev.parent);
    /* Find out todo. */
    spin_lock_irq(cdev->ccwlock);
    todo = priv->todo;
    priv->todo = CDEV_TODO_NOTHING;
    CIO_MSG_EVENT(4, "cdev_todo: cdev=0.%x.%04x todo=%d\n",
              priv->dev_id.ssid, priv->dev_id.devno, todo);
    spin_unlock_irq(cdev->ccwlock);
    /* Perform todo. */
    switch (todo) {
    case CDEV_TODO_ENABLE_CMF:
        cmf_reenable(cdev);
        break;
    case CDEV_TODO_REBIND:
        ccw_device_do_unbind_bind(cdev);
        break;
    case CDEV_TODO_REGISTER:
        io_subchannel_register(cdev);
        break;
    case CDEV_TODO_UNREG_EVAL:
        if (!sch_is_pseudo_sch(sch))
            css_schedule_eval(sch->schid);
        /* fall-through */
    case CDEV_TODO_UNREG:
        if (sch_is_pseudo_sch(sch))
            ccw_device_unregister(cdev);
        else
            ccw_device_call_sch_unregister(cdev);
        break;
    default:
        break;
    }
    /* Release workqueue ref. */
    put_device(&cdev->dev);
}

void ccw_device_sched_todo(struct ccw_device *cdev, enum cdev_todo todo)
{
    CIO_MSG_EVENT(4, "cdev_todo: sched cdev=0.%x.%04x todo=%d\n",
              cdev->private->dev_id.ssid, cdev->private->dev_id.devno,
              todo);
    if (cdev->private->todo >= todo)
        return;
    cdev->private->todo = todo;
    /* Get workqueue ref. */
    if (!get_device(&cdev->dev))
        return;
    if (!queue_work(cio_work_q, &cdev->private->todo_work)) {
        /* Already queued, release workqueue ref. */
        put_device(&cdev->dev);
    }
}

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

    return chsc_siosl(sch->schid);
}
EXPORT_SYMBOL_GPL(ccw_device_siosl);

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_GPL(ccw_device_get_subchannel_id);