// SPDX-License-Identifier: GPL-1.0+
/*
 *  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)
 */

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

#include <linux/export.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/delay.h>
#include <linux/timer.h>
#include <linux/kernel_stat.h>
#include <linux/sched/signal.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 };

static atomic_t ccw_device_init_count = ATOMIC_INIT(0);
static DECLARE_WAIT_QUEUE_HEAD(ccw_device_init_wq);
static struct bus_type ccw_bus_type;

/******************* 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 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(struct timer_list *unused);

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

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;

        timer_setup(&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 **************************/

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 *);

/**
 * 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)
{
        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;
        }
        spin_lock_irq(cdev->ccwlock);
        sch = to_subchannel(cdev->dev.parent);
        cdev->online = 0;
        /* 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_warn("%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_warn("%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;
}

/**
 * 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;
        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_warn("%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_warn("%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;

        spin_lock_irq(cdev->ccwlock);
        cdev->online = 1;
        spin_unlock_irq(cdev->ccwlock);
        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;
        }
        /* Prevent conflict between pending work and on-/offline processing.*/
        if (work_pending(&cdev->private->todo_work)) {
                ret = -EAGAIN;
                goto out;
        }
        if (!strncmp(buf, "force\n", count)) {
                force = 1;
                i = 1;
                ret = 0;
        } else {
                force = 0;
                ret = kstrtoul(buf, 16, &i);
        }
        if (ret)
                goto out;

        device_lock(dev);
        switch (i) {
        case 0:
                ret = online_store_handle_offline(cdev);
                break;
        case 1:
                ret = online_store_handle_online(cdev, force);
                break;
        default:
                ret = -EINVAL;
        }
        device_unlock(dev);

out:
        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_warn("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 ssize_t vpm_show(struct device *dev, struct device_attribute *attr,
                        char *buf)
{
        struct subchannel *sch = to_subchannel(dev);

        return sprintf(buf, "%02x\n", sch->vpm);
}

static DEVICE_ATTR_RO(devtype);
static DEVICE_ATTR_RO(cutype);
static DEVICE_ATTR_RO(modalias);
static DEVICE_ATTR_RW(online);
static DEVICE_ATTR(availability, 0444, available_show, NULL);
static DEVICE_ATTR(logging, 0200, NULL, initiate_logging);
static DEVICE_ATTR_RO(vpm);

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

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

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

static int ccw_device_add(struct ccw_device *cdev)
{
        struct device *dev = &cdev->dev;

        dev->bus = &ccw_bus_type;
        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);
}

/**
 * get_ccwdev_by_dev_id() - obtain device from a ccw device id
 * @dev_id: id of the device to be searched
 *
 * This function searches all devices attached to the ccw bus for a device
 * matching @dev_id.
 * Returns:
 *  If a device is found its reference count is increased and returned;
 *  else %NULL is returned.
 */
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)
{
        struct ccw_device_private *priv = cdev->private;
        int ret;

        priv->cdev = cdev;
        priv->int_class = IRQIO_CIO;
        priv->state = DEV_STATE_NOT_OPER;
        priv->dev_id.devno = sch->schib.pmcw.dev;
        priv->dev_id.ssid = sch->schid.ssid;

        INIT_WORK(&priv->todo_work, ccw_device_todo);
        INIT_LIST_HEAD(&priv->cmb_list);
        init_waitqueue_head(&priv->wait_q);
        timer_setup(&priv->timer, ccw_device_timeout, 0);

        atomic_set(&priv->onoff, 0);
        cdev->ccwlock = sch->lock;
        cdev->dev.parent = &sch->dev;
        cdev->dev.release = ccw_device_release;
        cdev->dev.groups = ccwdev_attr_groups;
        /* Do first half of device_register. */
        device_initialize(&cdev->dev);
        ret = dev_set_name(&cdev->dev, "0.%x.%04x", cdev->private->dev_id.ssid,
                           cdev->private->dev_id.devno);
        if (ret)
                goto out_put;
        if (!get_device(&sch->dev)) {
                ret = -ENODEV;
                goto out_put;
        }
        priv->flags.initialized = 1;
        spin_lock_irq(sch->lock);
        sch_set_cdev(sch, cdev);
        spin_unlock_irq(sch->lock);
        return 0;

out_put:
        /* Release reference from device_initialize(). */
        put_device(&cdev->dev);
        return ret;
}

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

        /* Start async. device sensing. */
        spin_lock_irq(sch->lock);
        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->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
                inc_irq_stat(IRQIO_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);
                rc = ccw_device_add(cdev);
                if (rc) {
                        /* Release online reference. */
                        put_device(&cdev->dev);
                        goto out_schedule;
                }
                if (atomic_dec_and_test(&ccw_device_init_count))
                        wake_up(&ccw_device_init_wq);
                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;

        ccw_device_unregister(cdev);
        spin_lock_irq(sch->lock);
        sch_set_cdev(sch, NULL);
        set_io_private(sch, NULL);
        spin_unlock_irq(sch->lock);
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);
        struct subchannel *sch;
        int *redo = data;

        spin_lock_irq(cdev->ccwlock);
        switch (cdev->private->state) {
        case DEV_STATE_ONLINE:
                sch = to_subchannel(cdev->dev.parent);
                if ((sch->schib.pmcw.pam & sch->opm) == sch->vpm)
                        break;
                /* fall through */
        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(3, "recovery: end\n");
}

static DECLARE_WORK(recovery_work, recovery_work_func);

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

void ccw_device_schedule_recovery(void)
{
        unsigned long flags;

        CIO_MSG_EVENT(3, "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;
}

/**
 * ccw_purge_blacklisted - purge unused, blacklisted devices
 *
 * Unregister all ccw devices that are offline and on the blacklist.
 */
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;
}

/**
 * io_subchannel_sch_event - process subchannel event
 * @sch: subchannel
 * @process: non-zero if function is called in process context
 *
 * An unspecified event occurred for this subchannel. Adjust data according
 * to the current operational state of the subchannel and device. Return
 * zero when the event has been handled sufficiently or -EAGAIN when this
 * function should be called again in process context.
 */
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;
}

static void ccw_device_set_int_class(struct ccw_device *cdev)
{
        struct ccw_driver *cdrv = cdev->drv;

        /* 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 = IRQIO_CIO;
}

#ifdef CONFIG_CCW_CONSOLE
int __init ccw_device_enable_console(struct ccw_device *cdev)
{
        struct subchannel *sch = to_subchannel(cdev->dev.parent);
        int rc;

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

        io_subchannel_init_fields(sch);
        rc = cio_commit_config(sch);
        if (rc)
                return rc;
        sch->driver = &io_subchannel_driver;
        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))
                ccw_device_wait_idle(cdev);

        /* Hold on to an extra reference while device is online. */
        get_device(&cdev->dev);
        rc = ccw_device_online(cdev);
        if (rc)
                goto out_unlock;

        while (!dev_fsm_final_state(cdev))
                ccw_device_wait_idle(cdev);

        if (cdev->private->state == DEV_STATE_ONLINE)
                cdev->online = 1;
        else
                rc = -EIO;
out_unlock:
        spin_unlock_irq(cdev->ccwlock);
        if (rc) /* Give up online reference since onlining failed. */
                put_device(&cdev->dev);
        return rc;
}

struct ccw_device * __init ccw_device_create_console(struct ccw_driver *drv)
{
        struct io_subchannel_private *io_priv;
        struct ccw_device *cdev;
        struct subchannel *sch;

        sch = cio_probe_console();
        if (IS_ERR(sch))
                return ERR_CAST(sch);

        io_priv = kzalloc(sizeof(*io_priv), GFP_KERNEL | GFP_DMA);
        if (!io_priv) {
                put_device(&sch->dev);
                return ERR_PTR(-ENOMEM);
        }
        set_io_private(sch, io_priv);
        cdev = io_subchannel_create_ccwdev(sch);
        if (IS_ERR(cdev)) {
                put_device(&sch->dev);
                kfree(io_priv);
                return cdev;
        }
        cdev->drv = drv;
        ccw_device_set_int_class(cdev);
        return cdev;
}

void __init ccw_device_destroy_console(struct ccw_device *cdev)
{
        struct subchannel *sch = to_subchannel(cdev->dev.parent);
        struct io_subchannel_private *io_priv = to_io_private(sch);

        set_io_private(sch, NULL);
        put_device(&sch->dev);
        put_device(&cdev->dev);
        kfree(io_priv);
}

/**
 * ccw_device_wait_idle() - busy wait for device to become idle
 * @cdev: ccw device
 *
 * Poll until activity control is zero, that is, no function or data
 * transfer is pending/active.
 * Called with device lock being held.
 */
void ccw_device_wait_idle(struct ccw_device *cdev)
{
        struct subchannel *sch = to_subchannel(cdev->dev.parent);

        while (1) {
                cio_tsch(sch);
                if (sch->schib.scsw.cmd.actl == 0)
                        break;
                udelay_simple(100);
        }
}

static int ccw_device_pm_restore(struct device *dev);

int ccw_device_force_console(struct ccw_device *cdev)
{
        return ccw_device_pm_restore(&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);
}


/**
 * 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;

        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 */
        ccw_device_set_int_class(cdev);
        ret = cdrv->probe ? cdrv->probe(cdev) : -ENODEV;
        if (ret) {
                cdev->drv = NULL;
                cdev->private->int_class = IRQIO_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;
        struct subchannel *sch;
        int ret;

        if (cdrv->remove)
                cdrv->remove(cdev);

        spin_lock_irq(cdev->ccwlock);
        if (cdev->online) {
                cdev->online = 0;
                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);
                spin_lock_irq(cdev->ccwlock);
        }
        ccw_device_set_timeout(cdev, 0);
        cdev->drv = NULL;
        cdev->private->int_class = IRQIO_CIO;
        sch = to_subchannel(cdev->dev.parent);
        spin_unlock_irq(cdev->ccwlock);
        io_subchannel_quiesce(sch);
        __disable_cmf(cdev);

        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,
};

/**
 * 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;

        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);
}

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);
}

/**
 * ccw_device_sched_todo - schedule ccw device operation
 * @cdev: ccw device
 * @todo: todo
 *
 * Schedule the operation identified by @todo to be performed on the slow path
 * workqueue. Do nothing if another operation with higher priority is already
 * scheduled. Needs to be called with ccwdev lock held.
 */
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);
        }
}

/**
 * ccw_device_siosl() - initiate logging
 * @cdev: ccw device
 *
 * This function is used to invoke model-dependent logging within the channel
 * subsystem.
 */
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);

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);