device.c 56.8 KB
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/*
 *  drivers/s390/cio/device.c
 *  bus driver for ccw devices
 *
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 *    Copyright IBM Corp. 2002,2008
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 *    Author(s): Arnd Bergmann (arndb@de.ibm.com)
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 *		 Cornelia Huck (cornelia.huck@de.ibm.com)
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 *		 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>
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#include <linux/timer.h>
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#include <asm/ccwdev.h>
#include <asm/cio.h>
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#include <asm/param.h>		/* HZ */
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#include <asm/cmb.h>
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#include <asm/isc.h>
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#include "chp.h"
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#include "cio.h"
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#include "cio_debug.h"
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#include "css.h"
#include "device.h"
#include "ioasm.h"
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#include "io_sch.h"
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#include "blacklist.h"
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static struct timer_list recovery_timer;
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static DEFINE_SPINLOCK(recovery_lock);
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static int recovery_phase;
static const unsigned long recovery_delay[] = { 3, 30, 300 };

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/******************* 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;
}

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/* 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). */
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static int snprint_alias(char *buf, size_t size,
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			 struct ccw_device_id *id, const char *suffix)
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{
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	int len;
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	len = snprintf(buf, size, "ccw:t%04Xm%02X", id->cu_type, id->cu_model);
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	if (len > size)
		return len;
	buf += len;
	size -= len;
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	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);
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	return len;
}

/* Set up environment variables for ccw device uevent. Return 0 on success,
 * non-zero otherwise. */
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static int ccw_uevent(struct device *dev, struct kobj_uevent_env *env)
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{
	struct ccw_device *cdev = to_ccwdev(dev);
	struct ccw_device_id *id = &(cdev->id);
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	int ret;
	char modalias_buf[30];
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	/* CU_TYPE= */
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	ret = add_uevent_var(env, "CU_TYPE=%04X", id->cu_type);
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	if (ret)
		return ret;
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	/* CU_MODEL= */
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	ret = add_uevent_var(env, "CU_MODEL=%02X", id->cu_model);
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	if (ret)
		return ret;
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	/* The next two can be zero, that's ok for us */
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	/* DEV_TYPE= */
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	ret = add_uevent_var(env, "DEV_TYPE=%04X", id->dev_type);
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	if (ret)
		return ret;
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	/* DEV_MODEL= */
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	ret = add_uevent_var(env, "DEV_MODEL=%02X", id->dev_model);
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	if (ret)
		return ret;
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	/* MODALIAS=  */
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	snprint_alias(modalias_buf, sizeof(modalias_buf), id, "");
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	ret = add_uevent_var(env, "MODALIAS=%s", modalias_buf);
	return ret;
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}

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struct bus_type ccw_bus_type;
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static void io_subchannel_irq(struct subchannel *);
static int io_subchannel_probe(struct subchannel *);
static int io_subchannel_remove(struct subchannel *);
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static void io_subchannel_shutdown(struct subchannel *);
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static int io_subchannel_sch_event(struct subchannel *, int);
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static int io_subchannel_chp_event(struct subchannel *, struct chp_link *,
				   int);
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static struct css_device_id io_subchannel_ids[] = {
	{ .match_flags = 0x1, .type = SUBCHANNEL_TYPE_IO, },
	{ /* end of list */ },
};
MODULE_DEVICE_TABLE(css, io_subchannel_ids);

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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;
}

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

struct workqueue_struct *ccw_device_work;
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wait_queue_head_t ccw_device_init_wq;
atomic_t ccw_device_init_count;
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static void recovery_func(unsigned long data);

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static int __init
init_ccw_bus_type (void)
{
	int ret;

	init_waitqueue_head(&ccw_device_init_wq);
	atomic_set(&ccw_device_init_count, 0);
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	setup_timer(&recovery_timer, recovery_func, 0);
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	ccw_device_work = create_singlethread_workqueue("cio");
	if (!ccw_device_work)
		return -ENOMEM; /* FIXME: better errno ? */
	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;

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	ret = css_driver_register(&io_subchannel_driver);
	if (ret)
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		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 (slow_path_wq)
		destroy_workqueue(slow_path_wq);
	return ret;
}

static void __exit
cleanup_ccw_bus_type (void)
{
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	css_driver_unregister(&io_subchannel_driver);
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	bus_unregister(&ccw_bus_type);
	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
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chpids_show (struct device * dev, struct device_attribute *attr, char * buf)
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{
	struct subchannel *sch = to_subchannel(dev);
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	struct chsc_ssd_info *ssd = &sch->ssd_info;
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	ssize_t ret = 0;
	int chp;
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	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 ");
	}
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	ret += sprintf (buf+ret, "\n");
	return min((ssize_t)PAGE_SIZE, ret);
}

static ssize_t
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pimpampom_show (struct device * dev, struct device_attribute *attr, char * buf)
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{
	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
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devtype_show (struct device *dev, struct device_attribute *attr, char *buf)
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{
	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
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cutype_show (struct device *dev, struct device_attribute *attr, char *buf)
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{
	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);
}

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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);
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	int len;
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	len = snprint_alias(buf, PAGE_SIZE, id, "\n");
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	return len > PAGE_SIZE ? PAGE_SIZE : len;
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}

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

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

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

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

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static void ccw_device_remove_orphan_cb(struct work_struct *work)
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{
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	struct ccw_device_private *priv;
	struct ccw_device *cdev;
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	priv = container_of(work, struct ccw_device_private, kick_work);
	cdev = priv->cdev;
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	ccw_device_unregister(cdev);
	put_device(&cdev->dev);
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	/* Release cdev reference for workqueue processing. */
	put_device(&cdev->dev);
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}

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static void
ccw_device_remove_disconnected(struct ccw_device *cdev)
{
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	unsigned long flags;
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	/*
	 * Forced offline in disconnected state means
	 * 'throw away device'.
	 */
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	if (ccw_device_is_orphan(cdev)) {
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		/*
		 * Deregister ccw device.
		 * Unfortunately, we cannot do this directly from the
		 * attribute method.
		 */
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		/* Get cdev reference for workqueue processing. */
		if (!get_device(&cdev->dev))
			return;
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		spin_lock_irqsave(cdev->ccwlock, flags);
		cdev->private->state = DEV_STATE_NOT_OPER;
		spin_unlock_irqrestore(cdev->ccwlock, flags);
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		PREPARE_WORK(&cdev->private->kick_work,
				ccw_device_remove_orphan_cb);
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		queue_work(slow_path_wq, &cdev->private->kick_work);
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	} else
		/* Deregister subchannel, which will kill the ccw device. */
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		ccw_device_schedule_sch_unregister(cdev);
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}

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/**
 * 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)
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{
	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);
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	/* Wait until a final state or DISCONNECTED is reached */
	while (!dev_fsm_final_state(cdev) &&
	       cdev->private->state != DEV_STATE_DISCONNECTED) {
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		spin_unlock_irq(cdev->ccwlock);
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		wait_event(cdev->private->wait_q, (dev_fsm_final_state(cdev) ||
			   cdev->private->state == DEV_STATE_DISCONNECTED));
		spin_lock_irq(cdev->ccwlock);
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	}
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	ret = ccw_device_offline(cdev);
	if (ret)
		goto error;
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	spin_unlock_irq(cdev->ccwlock);
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	wait_event(cdev->private->wait_q, (dev_fsm_final_state(cdev) ||
		   cdev->private->state == DEV_STATE_DISCONNECTED));
	/* Give up reference from ccw_device_set_online(). */
	put_device(&cdev->dev);
	return 0;

error:
	CIO_MSG_EVENT(0, "ccw_device_offline returned %d, device 0.%x.%04x\n",
		      ret, cdev->private->dev_id.ssid,
		      cdev->private->dev_id.devno);
	cdev->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;
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}

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/**
 * 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)
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{
	int ret;
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	int ret2;
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	if (!cdev)
		return -ENODEV;
	if (cdev->online || !cdev->drv)
		return -EINVAL;
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	/* Hold on to an extra reference while device is online. */
	if (!get_device(&cdev->dev))
		return -ENODEV;
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	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 {
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		CIO_MSG_EVENT(0, "ccw_device_online returned %d, "
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			      "device 0.%x.%04x\n",
			      ret, cdev->private->dev_id.ssid,
			      cdev->private->dev_id.devno);
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		/* Give up online reference since onlining failed. */
		put_device(&cdev->dev);
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		return ret;
	}
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	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);
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		/* Give up online reference since onlining failed. */
		put_device(&cdev->dev);
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		return -ENODEV;
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	}
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	spin_unlock_irq(cdev->ccwlock);
	if (cdev->drv->set_online)
		ret = cdev->drv->set_online(cdev);
	if (ret)
		goto rollback;
	cdev->online = 1;
	return 0;

rollback:
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	spin_lock_irq(cdev->ccwlock);
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	/* 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;
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	spin_unlock_irq(cdev->ccwlock);
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	/* Give up online reference since onlining failed. */
	put_device(&cdev->dev);
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	return ret;
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}

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static int online_store_handle_offline(struct ccw_device *cdev)
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{
	if (cdev->private->state == DEV_STATE_DISCONNECTED)
		ccw_device_remove_disconnected(cdev);
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	else if (cdev->online && cdev->drv && cdev->drv->set_offline)
		return ccw_device_set_offline(cdev);
	return 0;
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}

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

	/* Do device recognition, if needed. */
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	if (cdev->private->state == DEV_STATE_BOXED) {
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		ret = ccw_device_recognition(cdev);
		if (ret) {
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			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);
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			return ret;
		}
		wait_event(cdev->private->wait_q,
			   cdev->private->flags.recog_done);
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		if (cdev->private->state != DEV_STATE_OFFLINE)
			/* recognition failed */
			return -EAGAIN;
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	}
	if (cdev->drv && cdev->drv->set_online)
		ccw_device_set_online(cdev);
	return 0;
}
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static int online_store_handle_online(struct ccw_device *cdev, int force)
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{
	int ret;

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

static ssize_t online_store (struct device *dev, struct device_attribute *attr,
			     const char *buf, size_t count)
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{
	struct ccw_device *cdev = to_ccwdev(dev);
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	int force, ret;
	unsigned long i;
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	if ((cdev->private->state != DEV_STATE_OFFLINE &&
	     cdev->private->state != DEV_STATE_ONLINE &&
	     cdev->private->state != DEV_STATE_BOXED &&
	     cdev->private->state != DEV_STATE_DISCONNECTED) ||
	    atomic_cmpxchg(&cdev->private->onoff, 0, 1) != 0)
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		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;
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		ret = 0;
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	} else {
		force = 0;
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		ret = strict_strtoul(buf, 16, &i);
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	}
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	if (ret)
		goto out;
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	switch (i) {
	case 0:
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		ret = online_store_handle_offline(cdev);
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		break;
	case 1:
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		ret = online_store_handle_online(cdev, force);
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		break;
	default:
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		ret = -EINVAL;
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	}
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out:
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	if (cdev->drv)
		module_put(cdev->drv->owner);
	atomic_set(&cdev->private->onoff, 0);
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	return (ret < 0) ? ret : count;
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}

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

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	if (ccw_device_is_orphan(cdev))
		return sprintf(buf, "no device\n");
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	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);
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static DEVICE_ATTR(modalias, 0444, modalias_show, NULL);
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static DEVICE_ATTR(online, 0644, online_show, online_store);
static DEVICE_ATTR(availability, 0444, available_show, NULL);

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

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

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

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static struct attribute_group *ccwdev_attr_groups[] = {
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	&ccwdev_attr_group,
	NULL,
};
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/* this is a simple abstraction for device_register that sets the
 * correct bus type and adds the bus specific files */
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static int ccw_device_register(struct ccw_device *cdev)
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{
	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;
}

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

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

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

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static struct ccw_device * get_disc_ccwdev_by_dev_id(struct ccw_dev_id *dev_id,
						     struct ccw_device *sibling)
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{
	struct device *dev;
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	struct match_data data;
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	data.dev_id = *dev_id;
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	data.sibling = sibling;
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	dev = bus_find_device(&ccw_bus_type, NULL, &data, match_devno);
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	return dev ? to_ccwdev(dev) : NULL;
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}

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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;
}

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void ccw_device_do_unbind_bind(struct work_struct *work)
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{
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	struct ccw_device_private *priv;
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	struct ccw_device *cdev;
	struct subchannel *sch;
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	int ret;
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	priv = container_of(work, struct ccw_device_private, kick_work);
	cdev = priv->cdev;
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	sch = to_subchannel(cdev->dev.parent);
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	if (test_bit(1, &cdev->private->registered)) {
		device_release_driver(&cdev->dev);
		ret = device_attach(&cdev->dev);
		WARN_ON(ret == -ENODEV);
	}
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}

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

	cdev = to_ccwdev(dev);
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	/* Release reference of parent subchannel. */
	put_device(cdev->dev.parent);
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	kfree(cdev->private);
	kfree(cdev);
}

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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;
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	INIT_WORK(&cdev->private->kick_work, NULL);
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	cdev->dev.groups = ccwdev_attr_groups;
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	/* Do first half of device_register. */
	device_initialize(&cdev->dev);
	if (!get_device(&sch->dev)) {
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		/* Release reference from device_initialize(). */
		put_device(&cdev->dev);
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		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);
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		if (ret)
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			cdev = ERR_PTR(ret);
	}
	return cdev;
}

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

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

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

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

static void sch_attach_orphaned_device(struct subchannel *sch,
				       struct ccw_device *cdev)
{
	int ret;
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	struct subchannel *pseudo_sch;
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	/* Get reference for new parent. */
	if (!get_device(&sch->dev))
		return;
	pseudo_sch = to_subchannel(cdev->dev.parent);
	/*
	 * Try to move the ccw device to its new subchannel.
	 * Note: device_move() changes cdev->dev.parent
	 */
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	ret = device_move(&cdev->dev, &sch->dev, DPM_ORDER_PARENT_BEFORE_DEV);
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	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);
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		/* Put reference for new parent. */
		put_device(&sch->dev);
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		return;
	}
	sch_attach_device(sch, cdev);
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	/* Put reference on pseudo subchannel. */
	put_device(&pseudo_sch->dev);
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}

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);
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	sch_set_cdev(sch, cdev);
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	spin_unlock_irq(sch->lock);
	/* Start recognition for the new ccw device. */
	if (io_subchannel_recog(cdev, sch)) {
		spin_lock_irq(sch->lock);
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		sch_set_cdev(sch, NULL);
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		spin_unlock_irq(sch->lock);
		css_sch_device_unregister(sch);
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		/* Put reference from io_subchannel_create_ccwdev(). */
		put_device(&sch->dev);
		/* Give up initial reference. */
		put_device(&cdev->dev);
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	}
}


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;

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	/* Increase refcount for pseudo subchannel. */
	get_device(&css->pseudo_subchannel->dev);
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	/*
	 * Move the orphaned ccw device to the orphanage so the replacing
	 * ccw device can take its place on the subchannel.
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	 * Note: device_move() changes cdev->dev.parent
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	 */
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	ret = device_move(&cdev->dev, &css->pseudo_subchannel->dev,
		DPM_ORDER_NONE);
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	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);
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		/* Decrease refcount for pseudo subchannel again. */
		put_device(&css->pseudo_subchannel->dev);
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		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);
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		/* Release reference from get_disc_ccwdev_by_dev_id() */
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		put_device(&replacing_cdev->dev);
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		/* Release reference of subchannel from old cdev. */
		put_device(&sch->dev);
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		return;
	}
	replacing_cdev = get_orphaned_ccwdev_by_dev_id(css, &dev_id);
	if (replacing_cdev) {
		sch_attach_orphaned_device(sch, replacing_cdev);
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		/* Release reference from get_orphaned_ccwdev_by_dev_id() */
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		put_device(&replacing_cdev->dev);
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		/* Release reference of subchannel from old cdev. */
		put_device(&sch->dev);
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		return;
	}
	sch_create_and_recog_new_device(sch);
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	/* Release reference of subchannel from old cdev. */
	put_device(&sch->dev);
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}

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

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	priv = container_of(work, struct ccw_device_private, kick_work);
	cdev = priv->cdev;
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	sch = to_subchannel(cdev->dev.parent);
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	/*
	 * 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;
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	css_update_ssd_info(sch);
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	/*
	 * 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.
	 */
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	if (device_is_registered(&cdev->dev)) {
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		if (!cdev->drv) {
			ret = device_reprobe(&cdev->dev);
			if (ret)
				/* We can't do much here. */
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				CIO_MSG_EVENT(0, "device_reprobe() returned"
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					      " %d for 0.%x.%04x\n", ret,
					      cdev->private->dev_id.ssid,
					      cdev->private->dev_id.devno);
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		}
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		goto out;
	}
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	/*
	 * Now we know this subchannel will stay, we can throw
	 * our delayed uevent.
	 */
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	dev_set_uevent_suppress(&sch->dev, 0);
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	kobject_uevent(&sch->dev.kobj, KOBJ_ADD);
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	/* make it known to the system */
	ret = ccw_device_register(cdev);
	if (ret) {
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		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);
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		spin_lock_irqsave(sch->lock, flags);
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		sch_set_cdev(sch, NULL);
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		spin_unlock_irqrestore(sch->lock, flags);
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		/* Release initial device reference. */
		put_device(&cdev->dev);
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		goto out_err;
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	}
out:
	cdev->private->flags.recog_done = 1;
	wake_up(&cdev->private->wait_q);
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out_err:
	/* Release reference for workqueue processing. */
	put_device(&cdev->dev);
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	if (atomic_dec_and_test(&ccw_device_init_count))
		wake_up(&ccw_device_init_wq);
}

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

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	priv = container_of(work, struct ccw_device_private, kick_work);
	cdev = priv->cdev;
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	/* Get subchannel reference for local processing. */
	if (!get_device(cdev->dev.parent))