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device.c

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

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

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

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

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

      if (!ids)
            return 0;

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

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

      return 1;
}

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

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

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

      return len;
}

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

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

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

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

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

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

struct bus_type ccw_bus_type;

static int io_subchannel_probe (struct subchannel *);
static int io_subchannel_remove (struct subchannel *);
static int io_subchannel_notify(struct device *, int);
static void io_subchannel_verify(struct device *);
static void io_subchannel_ioterm(struct device *);
static void io_subchannel_shutdown(struct subchannel *);

static struct css_driver io_subchannel_driver = {
      .subchannel_type = SUBCHANNEL_TYPE_IO,
      .drv = {
            .name = "io_subchannel",
            .bus  = &css_bus_type,
      },
      .irq = io_subchannel_irq,
      .notify = io_subchannel_notify,
      .verify = io_subchannel_verify,
      .termination = io_subchannel_ioterm,
      .probe = io_subchannel_probe,
      .remove = io_subchannel_remove,
      .shutdown = io_subchannel_shutdown,
};

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

static int __init
init_ccw_bus_type (void)
{
      int ret;

      init_waitqueue_head(&ccw_device_init_wq);
      atomic_set(&ccw_device_init_count, 0);

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

      if ((ret = driver_register(&io_subchannel_driver.drv)))
            goto out_err;

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

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

subsys_initcall(init_ccw_bus_type);
module_exit(cleanup_ccw_bus_type);

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

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

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

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

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

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

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

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

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

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

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

      return len > PAGE_SIZE ? PAGE_SIZE : len;
}

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

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

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

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

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

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

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

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

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

      /*
       * Forced offline in disconnected state means
       * 'throw away device'.
       */
      if (ccw_device_is_orphan(cdev)) {
            /*
             * Deregister ccw device.
             * Unfortunately, we cannot do this directly from the
             * attribute method.
             */
            spin_lock_irqsave(cdev->ccwlock, flags);
            cdev->private->state = DEV_STATE_NOT_OPER;
            spin_unlock_irqrestore(cdev->ccwlock, flags);
            rc = device_schedule_callback(&cdev->dev,
                                    ccw_device_remove_orphan_cb);
            if (rc)
                  CIO_MSG_EVENT(2, "Couldn't unregister orphan "
                              "0.%x.%04x\n",
                              cdev->private->dev_id.ssid,
                              cdev->private->dev_id.devno);
            return;
      }
      /* Deregister subchannel, which will kill the ccw device. */
      rc = device_schedule_callback(cdev->dev.parent,
                              ccw_device_remove_sch_cb);
      if (rc)
            CIO_MSG_EVENT(2, "Couldn't unregister disconnected device "
                        "0.%x.%04x\n",
                        cdev->private->dev_id.ssid,
                        cdev->private->dev_id.devno);
}

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

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

      if (cdev->drv->set_offline) {
            ret = cdev->drv->set_offline(cdev);
            if (ret != 0)
                  return ret;
      }
      cdev->online = 0;
      spin_lock_irq(cdev->ccwlock);
      ret = ccw_device_offline(cdev);
      if (ret == -ENODEV) {
            if (cdev->private->state != DEV_STATE_NOT_OPER) {
                  cdev->private->state = DEV_STATE_OFFLINE;
                  dev_fsm_event(cdev, DEV_EVENT_NOTOPER);
            }
            spin_unlock_irq(cdev->ccwlock);
            return ret;
      }
      spin_unlock_irq(cdev->ccwlock);
      if (ret == 0)
            wait_event(cdev->private->wait_q, dev_fsm_final_state(cdev));
      else {
            CIO_MSG_EVENT(2, "ccw_device_offline returned %d, "
                        "device 0.%x.%04x\n",
                        ret, cdev->private->dev_id.ssid,
                        cdev->private->dev_id.devno);
            cdev->online = 1;
      }
      return ret;
}

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

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

      spin_lock_irq(cdev->ccwlock);
      ret = ccw_device_online(cdev);
      spin_unlock_irq(cdev->ccwlock);
      if (ret == 0)
            wait_event(cdev->private->wait_q, dev_fsm_final_state(cdev));
      else {
            CIO_MSG_EVENT(2, "ccw_device_online returned %d, "
                        "device 0.%x.%04x\n",
                        ret, cdev->private->dev_id.ssid,
                        cdev->private->dev_id.devno);
            return ret;
      }
      if (cdev->private->state != DEV_STATE_ONLINE)
            return -ENODEV;
      if (!cdev->drv->set_online || cdev->drv->set_online(cdev) == 0) {
            cdev->online = 1;
            return 0;
      }
      spin_lock_irq(cdev->ccwlock);
      ret = ccw_device_offline(cdev);
      spin_unlock_irq(cdev->ccwlock);
      if (ret == 0)
            wait_event(cdev->private->wait_q, dev_fsm_final_state(cdev));
      else
            CIO_MSG_EVENT(2, "ccw_device_offline returned %d, "
                        "device 0.%x.%04x\n",
                        ret, cdev->private->dev_id.ssid,
                        cdev->private->dev_id.devno);
      return (ret == 0) ? -ENODEV : ret;
}

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

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

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

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

}

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

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

      if (cdev->drv && !try_module_get(cdev->drv->owner)) {
            atomic_set(&cdev->private->onoff, 0);
            return -EINVAL;
      }
      if (!strncmp(buf, "force\n", count)) {
            force = 1;
            i = 1;
      } else {
            force = 0;
            i = simple_strtoul(buf, &tmp, 16);
      }

      switch (i) {
      case 0:
            online_store_handle_offline(cdev);
            break;
      case 1:
            online_store_handle_online(cdev, force);
            break;
      default:
            count = -EINVAL;
      }
      if (cdev->drv)
            module_put(cdev->drv->owner);
      atomic_set(&cdev->private->onoff, 0);
      return 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 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);
extern struct device_attribute dev_attr_cmb_enable;
static DEVICE_ATTR(availability, 0444, available_show, NULL);

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

static struct attribute_group subch_attr_group = {
      .attrs = subch_attrs,
};

struct attribute_group *subch_attr_groups[] = {
      &subch_attr_group,
      NULL,
};

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

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

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

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

      dev->bus = &ccw_bus_type;

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

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

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

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

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

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

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

      return dev ? to_ccwdev(dev) : NULL;
}

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

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

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

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

      return dev ? to_ccwdev(dev) : NULL;
}

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

      other_sch = to_subchannel(get_device(cdev->dev.parent));
      ret = device_move(&cdev->dev, &sch->dev);
      if (ret) {
            CIO_MSG_EVENT(2, "Moving disconnected device 0.%x.%04x failed "
                        "(ret=%d)!\n", cdev->private->dev_id.ssid,
                        cdev->private->dev_id.devno, ret);
            put_device(&other_sch->dev);
            return;
      }
      other_sch->dev.driver_data = NULL;
      /* No need to keep a subchannel without ccw device around. */
      css_sch_device_unregister(other_sch);
      put_device(&other_sch->dev);
      sch_attach_device(sch, cdev);
}

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

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

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

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


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

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

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

/*
 * Register recognized device.
 */
static void
io_subchannel_register(struct work_struct *work)
{
      struct ccw_device_private *priv;
      struct ccw_device *cdev;
      struct subchannel *sch;
      int ret;
      unsigned long flags;

      priv = container_of(work, struct ccw_device_private, kick_work);
      cdev = priv->cdev;
      sch = to_subchannel(cdev->dev.parent);
      css_update_ssd_info(sch);
      /*
       * io_subchannel_register() will also be called after device
       * recognition has been done for a boxed device (which will already
       * be registered). We need to reprobe since we may now have sense id
       * information.
       */
      if (klist_node_attached(&cdev->dev.knode_parent)) {
            if (!cdev->drv) {
                  ret = device_reprobe(&cdev->dev);
                  if (ret)
                        /* We can't do much here. */
                        CIO_MSG_EVENT(2, "device_reprobe() returned"
                                    " %d for 0.%x.%04x\n", ret,
                                    cdev->private->dev_id.ssid,
                                    cdev->private->dev_id.devno);
            }
            goto out;
      }
      /*
       * Now we know this subchannel will stay, we can throw
       * our delayed uevent.
       */
      sch->dev.uevent_suppress = 0;
      kobject_uevent(&sch->dev.kobj, KOBJ_ADD);
      /* make it known to the system */
      ret = ccw_device_register(cdev);
      if (ret) {
            CIO_MSG_EVENT(0, "Could not register ccw dev 0.%x.%04x: %d\n",
                        cdev->private->dev_id.ssid,
                        cdev->private->dev_id.devno, ret);
            put_device(&cdev->dev);
            spin_lock_irqsave(sch->lock, flags);
            sch->dev.driver_data = NULL;
            spin_unlock_irqrestore(sch->lock, flags);
            kfree (cdev->private);
            kfree (cdev);
            put_device(&sch->dev);
            if (atomic_dec_and_test(&ccw_device_init_count))
                  wake_up(&ccw_device_init_wq);
            return;
      }
      put_device(&cdev->dev);
out:
      cdev->private->flags.recog_done = 1;
      put_device(&sch->dev);
      wake_up(&cdev->private->wait_q);
      if (atomic_dec_and_test(&ccw_device_init_count))
            wake_up(&ccw_device_init_wq);
}

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

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

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

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

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

      sch->dev.driver_data = cdev;
      sch->driver = &io_subchannel_driver;
      cdev->ccwlock = sch->lock;

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

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

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

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

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

      priv = container_of(work, struct ccw_device_private, kick_work);
      sch = priv->sch;
      cdev = priv->cdev;
      former_parent = ccw_device_is_orphan(cdev) ?
            NULL : to_subchannel(get_device(cdev->dev.parent));
      mutex_lock(&sch->reg_mutex);
      /* Try to move the ccw device to its new subchannel. */
      rc = device_move(&cdev->dev, &sch->dev);
      mutex_unlock(&sch->reg_mutex);
      if (rc) {
            CIO_MSG_EVENT(2, "Moving device 0.%x.%04x to subchannel "
                        "0.%x.%04x failed (ret=%d)!\n",
                        cdev->private->dev_id.ssid,
                        cdev->private->dev_id.devno, sch->schid.ssid,
                        sch->schid.sch_no, rc);
            css_sch_device_unregister(sch);
            goto out;
      }
      if (former_parent) {
            spin_lock_irq(former_parent->lock);
            former_parent->dev.driver_data = NULL;
            spin_unlock_irq(former_parent->lock);
            css_sch_device_unregister(former_parent);
            /* Reset intparm to zeroes. */
            former_parent->schib.pmcw.intparm = 0;
            cio_modify(former_parent);
      }
      sch_attach_device(sch, cdev);
out:
      if (former_parent)
            put_device(&former_parent->dev);
      put_device(&cdev->dev);
}

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

      if (sch->dev.driver_data) {
            /*
             * This subchannel already has an associated ccw_device.
             * Register it and exit. This happens for all early
             * device, e.g. the console.
             */
            cdev = sch->dev.driver_data;
            cdev->dev.groups = ccwdev_attr_groups;
            device_initialize(&cdev->dev);
            ccw_device_register(cdev);
            /*
             * Check if the device is already online. If it is
             * the reference count needs to be corrected
             * (see ccw_device_online and css_init_done for the
             * ugly details).
             */
            if (cdev->private->state != DEV_STATE_NOT_OPER &&
                cdev->private->state != DEV_STATE_OFFLINE &&
                cdev->private->state != DEV_STATE_BOXED)
                  get_device(&cdev->dev);
            return 0;
      }
      /*
       * First check if a fitting device may be found amongst the
       * disconnected devices or in the orphanage.
       */
      dev_id.devno = sch->schib.pmcw.dev;
      dev_id.ssid = sch->schid.ssid;
      cdev = get_disc_ccwdev_by_dev_id(&dev_id, NULL);
      if (!cdev)
            cdev = get_orphaned_ccwdev_by_dev_id(to_css(sch->dev.parent),
                                         &dev_id);
      if (cdev) {
            /*
             * Schedule moving the device until when we have a registered
             * subchannel to move to and succeed the probe. We can
             * unregister later again, when the probe is through.
             */
            cdev->private->sch = sch;
            PREPARE_WORK(&cdev->private->kick_work,
                       ccw_device_move_to_sch);
            queue_work(slow_path_wq, &cdev->private->kick_work);
            return 0;
      }
      cdev = io_subchannel_create_ccwdev(sch);
      if (IS_ERR(cdev))
            return PTR_ERR(cdev);

      rc = io_subchannel_recog(cdev, sch);
      if (rc) {
            spin_lock_irqsave(sch->lock, flags);
            sch->dev.driver_data = NULL;
            spin_unlock_irqrestore(sch->lock, flags);
            if (cdev->dev.release)
                  cdev->dev.release(&cdev->dev);
      }

      return rc;
}

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

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

static int
io_subchannel_notify(struct device *dev, int event)
{
      struct ccw_device *cdev;

      cdev = dev->driver_data;
      if (!cdev)
            return 0;
      if (!cdev->drv)
            return 0;
      if (!cdev->online)
            return 0;
      return cdev->drv->notify ? cdev->drv->notify(cdev, event) : 0;
}

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

      cdev = dev->driver_data;
      if (cdev)
            dev_fsm_event(cdev, DEV_EVENT_VERIFY);
}

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

      cdev = dev->driver_data;
      if (!cdev)
            return;
      /* Internal I/O will be retried by the interrupt handler. */
      if (cdev->private->flags.intretry)
            return;
      cdev->private->state = DEV_STATE_CLEAR_VERIFY;
      if (cdev->handler)
            cdev->handler(cdev, cdev->private->intparm,
                        ERR_PTR(-EIO));
}

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

      cdev = sch->dev.driver_data;

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

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

static DEFINE_SPINLOCK(ccw_console_lock);

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

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

      /* Initialize the ccw_device structure. */
      cdev->dev.parent= &sch->dev;
      rc = io_subchannel_recog(cdev, sch);
      if (rc)
            return rc;

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

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

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

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

      bus_id = id;

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


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

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

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

      return dev ? to_ccwdev(dev) : NULL;
}

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

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

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

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

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

      return 0;
}

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

      if (cdrv->remove)
            cdrv->remove(cdev);
      if (cdev->online) {
            cdev->online = 0;
            spin_lock_irq(cdev->ccwlock);
            ret = ccw_device_offline(cdev);
            spin_unlock_irq(cdev->ccwlock);
            if (ret == 0)
                  wait_event(cdev->private->wait_q,
                           dev_fsm_final_state(cdev));
            else
                  //FIXME: we can't fail!
                  CIO_MSG_EVENT(2, "ccw_device_offline returned %d, "
                              "device 0.%x.%04x\n",
                              ret, cdev->private->dev_id.ssid,
                              cdev->private->dev_id.devno);
      }
      ccw_device_set_timeout(cdev, 0);
      cdev->drv = NULL;
      return 0;
}

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

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

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

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

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

      return driver_register(drv);
}

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

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

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

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

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