/*
   * finite state machine for device handling
   *
   *    Copyright IBM Corp. 2002, 2008
   *    Author(s): Cornelia Huck (cornelia.huck@de.ibm.com)
   *		 Martin Schwidefsky (schwidefsky@de.ibm.com)
   */
  
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/jiffies.h>
  #include <linux/string.h>
  
  #include <asm/ccwdev.h>
  #include <asm/cio.h>
  #include <asm/chpid.h>
  
  #include "cio.h"
  #include "cio_debug.h"
  #include "css.h"
  #include "device.h"
  #include "chsc.h"
  #include "ioasm.h"
  #include "chp.h"
  
  static int timeout_log_enabled;
  
  static int __init ccw_timeout_log_setup(char *unused)
  {
  	timeout_log_enabled = 1;
  	return 1;
  }
  
  __setup("ccw_timeout_log", ccw_timeout_log_setup);
  
  static void ccw_timeout_log(struct ccw_device *cdev)
  {
  	struct schib schib;
  	struct subchannel *sch;
  	struct io_subchannel_private *private;
  	union orb *orb;
  	int cc;
  
  	sch = to_subchannel(cdev->dev.parent);
  	private = to_io_private(sch);
  	orb = &private->orb;
  	cc = stsch_err(sch->schid, &schib);
  
  	printk(KERN_WARNING "cio: ccw device timeout occurred at %llx, "
  	       "device information:
  ", get_tod_clock());
  	printk(KERN_WARNING "cio: orb:
  ");
  	print_hex_dump(KERN_WARNING, "cio:  ", DUMP_PREFIX_NONE, 16, 1,
  		       orb, sizeof(*orb), 0);
  	printk(KERN_WARNING "cio: ccw device bus id: %s
  ",
  	       dev_name(&cdev->dev));
  	printk(KERN_WARNING "cio: subchannel bus id: %s
  ",
  	       dev_name(&sch->dev));
  	printk(KERN_WARNING "cio: subchannel lpm: %02x, opm: %02x, "
  	       "vpm: %02x
  ", sch->lpm, sch->opm, sch->vpm);
  
  	if (orb->tm.b) {
  		printk(KERN_WARNING "cio: orb indicates transport mode
  ");
  		printk(KERN_WARNING "cio: last tcw:
  ");
  		print_hex_dump(KERN_WARNING, "cio:  ", DUMP_PREFIX_NONE, 16, 1,
  			       (void *)(addr_t)orb->tm.tcw,
  			       sizeof(struct tcw), 0);
  	} else {
  		printk(KERN_WARNING "cio: orb indicates command mode
  ");
  		if ((void *)(addr_t)orb->cmd.cpa == &private->sense_ccw ||
  		    (void *)(addr_t)orb->cmd.cpa == cdev->private->iccws)
  			printk(KERN_WARNING "cio: last channel program "
  			       "(intern):
  ");
  		else
  			printk(KERN_WARNING "cio: last channel program:
  ");
  
  		print_hex_dump(KERN_WARNING, "cio:  ", DUMP_PREFIX_NONE, 16, 1,
  			       (void *)(addr_t)orb->cmd.cpa,
  			       sizeof(struct ccw1), 0);
  	}
  	printk(KERN_WARNING "cio: ccw device state: %d
  ",
  	       cdev->private->state);
  	printk(KERN_WARNING "cio: store subchannel returned: cc=%d
  ", cc);
  	printk(KERN_WARNING "cio: schib:
  ");
  	print_hex_dump(KERN_WARNING, "cio:  ", DUMP_PREFIX_NONE, 16, 1,
  		       &schib, sizeof(schib), 0);
  	printk(KERN_WARNING "cio: ccw device flags:
  ");
  	print_hex_dump(KERN_WARNING, "cio:  ", DUMP_PREFIX_NONE, 16, 1,
  		       &cdev->private->flags, sizeof(cdev->private->flags), 0);
  }
  
  /*
   * Timeout function. It just triggers a DEV_EVENT_TIMEOUT.
   */
  static void
  ccw_device_timeout(unsigned long data)
  {
  	struct ccw_device *cdev;
  
  	cdev = (struct ccw_device *) data;
  	spin_lock_irq(cdev->ccwlock);
  	if (timeout_log_enabled)
  		ccw_timeout_log(cdev);
  	dev_fsm_event(cdev, DEV_EVENT_TIMEOUT);
  	spin_unlock_irq(cdev->ccwlock);
  }
  
  /*
   * Set timeout
   */
  void
  ccw_device_set_timeout(struct ccw_device *cdev, int expires)
  {
  	if (expires == 0) {
  		del_timer(&cdev->private->timer);
  		return;
  	}
  	if (timer_pending(&cdev->private->timer)) {
  		if (mod_timer(&cdev->private->timer, jiffies + expires))
  			return;
  	}
  	cdev->private->timer.function = ccw_device_timeout;
  	cdev->private->timer.data = (unsigned long) cdev;
  	cdev->private->timer.expires = jiffies + expires;
  	add_timer(&cdev->private->timer);
  }
  
  /*
   * Cancel running i/o. This is called repeatedly since halt/clear are
   * asynchronous operations. We do one try with cio_cancel, two tries
   * with cio_halt, 255 tries with cio_clear. If everythings fails panic.
   * Returns 0 if device now idle, -ENODEV for device not operational and
   * -EBUSY if an interrupt is expected (either from halt/clear or from a
   * status pending).
   */
  int
  ccw_device_cancel_halt_clear(struct ccw_device *cdev)
  {
  	struct subchannel *sch;
  	int ret;
  
  	sch = to_subchannel(cdev->dev.parent);
  	if (cio_update_schib(sch))
  		return -ENODEV; 
  	if (!sch->schib.pmcw.ena)
  		/* Not operational -> done. */
  		return 0;
  	/* Stage 1: cancel io. */
  	if (!(scsw_actl(&sch->schib.scsw) & SCSW_ACTL_HALT_PEND) &&
  	    !(scsw_actl(&sch->schib.scsw) & SCSW_ACTL_CLEAR_PEND)) {
  		if (!scsw_is_tm(&sch->schib.scsw)) {
  			ret = cio_cancel(sch);
  			if (ret != -EINVAL)
  				return ret;
  		}
  		/* cancel io unsuccessful or not applicable (transport mode).
  		 * Continue with asynchronous instructions. */
  		cdev->private->iretry = 3;	/* 3 halt retries. */
  	}
  	if (!(scsw_actl(&sch->schib.scsw) & SCSW_ACTL_CLEAR_PEND)) {
  		/* Stage 2: halt io. */
  		if (cdev->private->iretry) {
  			cdev->private->iretry--;
  			ret = cio_halt(sch);
  			if (ret != -EBUSY)
  				return (ret == 0) ? -EBUSY : ret;
  		}
  		/* halt io unsuccessful. */
  		cdev->private->iretry = 255;	/* 255 clear retries. */
  	}
  	/* Stage 3: clear io. */
  	if (cdev->private->iretry) {
  		cdev->private->iretry--;
  		ret = cio_clear (sch);
  		return (ret == 0) ? -EBUSY : ret;
  	}
  	/* Function was unsuccessful */
  	CIO_MSG_EVENT(0, "0.%x.%04x: could not stop I/O
  ",
  		      cdev->private->dev_id.ssid, cdev->private->dev_id.devno);
  	return -EIO;
  }
  
  void ccw_device_update_sense_data(struct ccw_device *cdev)
  {
  	memset(&cdev->id, 0, sizeof(cdev->id));
  	cdev->id.cu_type   = cdev->private->senseid.cu_type;
  	cdev->id.cu_model  = cdev->private->senseid.cu_model;
  	cdev->id.dev_type  = cdev->private->senseid.dev_type;
  	cdev->id.dev_model = cdev->private->senseid.dev_model;
  }
  
  int ccw_device_test_sense_data(struct ccw_device *cdev)
  {
  	return cdev->id.cu_type == cdev->private->senseid.cu_type &&
  		cdev->id.cu_model == cdev->private->senseid.cu_model &&
  		cdev->id.dev_type == cdev->private->senseid.dev_type &&
  		cdev->id.dev_model == cdev->private->senseid.dev_model;
  }
  
  /*
   * The machine won't give us any notification by machine check if a chpid has
   * been varied online on the SE so we have to find out by magic (i. e. driving
   * the channel subsystem to device selection and updating our path masks).
   */
  static void
  __recover_lost_chpids(struct subchannel *sch, int old_lpm)
  {
  	int mask, i;
  	struct chp_id chpid;
  
  	chp_id_init(&chpid);
  	for (i = 0; i<8; i++) {
  		mask = 0x80 >> i;
  		if (!(sch->lpm & mask))
  			continue;
  		if (old_lpm & mask)
  			continue;
  		chpid.id = sch->schib.pmcw.chpid[i];
  		if (!chp_is_registered(chpid))
  			css_schedule_eval_all();
  	}
  }
  
  /*
   * Stop device recognition.
   */
  static void
  ccw_device_recog_done(struct ccw_device *cdev, int state)
  {
  	struct subchannel *sch;
  	int old_lpm;
  
  	sch = to_subchannel(cdev->dev.parent);
  
  	if (cio_disable_subchannel(sch))
  		state = DEV_STATE_NOT_OPER;
  	/*
  	 * Now that we tried recognition, we have performed device selection
  	 * through ssch() and the path information is up to date.
  	 */
  	old_lpm = sch->lpm;
  
  	/* Check since device may again have become not operational. */
  	if (cio_update_schib(sch))
  		state = DEV_STATE_NOT_OPER;
  	else
  		sch->lpm = sch->schib.pmcw.pam & sch->opm;
  
  	if (cdev->private->state == DEV_STATE_DISCONNECTED_SENSE_ID)
  		/* Force reprobe on all chpids. */
  		old_lpm = 0;
  	if (sch->lpm != old_lpm)
  		__recover_lost_chpids(sch, old_lpm);
  	if (cdev->private->state == DEV_STATE_DISCONNECTED_SENSE_ID &&
  	    (state == DEV_STATE_NOT_OPER || state == DEV_STATE_BOXED)) {
  		cdev->private->flags.recog_done = 1;
  		cdev->private->state = DEV_STATE_DISCONNECTED;
  		wake_up(&cdev->private->wait_q);
  		return;
  	}
  	if (cdev->private->flags.resuming) {
  		cdev->private->state = state;
  		cdev->private->flags.recog_done = 1;
  		wake_up(&cdev->private->wait_q);
  		return;
  	}
  	switch (state) {
  	case DEV_STATE_NOT_OPER:
  		break;
  	case DEV_STATE_OFFLINE:
  		if (!cdev->online) {
  			ccw_device_update_sense_data(cdev);
  			break;
  		}
  		cdev->private->state = DEV_STATE_OFFLINE;
  		cdev->private->flags.recog_done = 1;
  		if (ccw_device_test_sense_data(cdev)) {
  			cdev->private->flags.donotify = 1;
  			ccw_device_online(cdev);
  			wake_up(&cdev->private->wait_q);
  		} else {
  			ccw_device_update_sense_data(cdev);
  			ccw_device_sched_todo(cdev, CDEV_TODO_REBIND);
  		}
  		return;
  	case DEV_STATE_BOXED:
  		if (cdev->id.cu_type != 0) { /* device was recognized before */
  			cdev->private->flags.recog_done = 1;
  			cdev->private->state = DEV_STATE_BOXED;
  			wake_up(&cdev->private->wait_q);
  			return;
  		}
  		break;
  	}
  	cdev->private->state = state;
  	io_subchannel_recog_done(cdev);
  	wake_up(&cdev->private->wait_q);
  }
  
  /*
   * Function called from device_id.c after sense id has completed.
   */
  void
  ccw_device_sense_id_done(struct ccw_device *cdev, int err)
  {
  	switch (err) {
  	case 0:
  		ccw_device_recog_done(cdev, DEV_STATE_OFFLINE);
  		break;
  	case -ETIME:		/* Sense id stopped by timeout. */
  		ccw_device_recog_done(cdev, DEV_STATE_BOXED);
  		break;
  	default:
  		ccw_device_recog_done(cdev, DEV_STATE_NOT_OPER);
  		break;
  	}
  }
  
  /**
    * ccw_device_notify() - inform the device's driver about an event
    * @cdev: device for which an event occurred
    * @event: event that occurred
    *
    * Returns:
    *   -%EINVAL if the device is offline or has no driver.
    *   -%EOPNOTSUPP if the device's driver has no notifier registered.
    *   %NOTIFY_OK if the driver wants to keep the device.
    *   %NOTIFY_BAD if the driver doesn't want to keep the device.
    */
  int ccw_device_notify(struct ccw_device *cdev, int event)
  {
  	int ret = -EINVAL;
  
  	if (!cdev->drv)
  		goto out;
  	if (!cdev->online)
  		goto out;
  	CIO_MSG_EVENT(2, "notify called for 0.%x.%04x, event=%d
  ",
  		      cdev->private->dev_id.ssid, cdev->private->dev_id.devno,
  		      event);
  	if (!cdev->drv->notify) {
  		ret = -EOPNOTSUPP;
  		goto out;
  	}
  	if (cdev->drv->notify(cdev, event))
  		ret = NOTIFY_OK;
  	else
  		ret = NOTIFY_BAD;
  out:
  	return ret;
  }
  
  static void ccw_device_oper_notify(struct ccw_device *cdev)
  {
  	struct subchannel *sch = to_subchannel(cdev->dev.parent);
  
  	if (ccw_device_notify(cdev, CIO_OPER) == NOTIFY_OK) {
  		/* Reenable channel measurements, if needed. */
  		ccw_device_sched_todo(cdev, CDEV_TODO_ENABLE_CMF);
  		/* Save indication for new paths. */
  		cdev->private->path_new_mask = sch->vpm;
  		return;
  	}
  	/* Driver doesn't want device back. */
  	ccw_device_set_notoper(cdev);
  	ccw_device_sched_todo(cdev, CDEV_TODO_REBIND);
  }
  
  /*
   * Finished with online/offline processing.
   */
  static void
  ccw_device_done(struct ccw_device *cdev, int state)
  {
  	struct subchannel *sch;
  
  	sch = to_subchannel(cdev->dev.parent);
  
  	ccw_device_set_timeout(cdev, 0);
  
  	if (state != DEV_STATE_ONLINE)
  		cio_disable_subchannel(sch);
  
  	/* Reset device status. */
  	memset(&cdev->private->irb, 0, sizeof(struct irb));
  
  	cdev->private->state = state;
  
  	switch (state) {
  	case DEV_STATE_BOXED:
  		CIO_MSG_EVENT(0, "Boxed device %04x on subchannel %04x
  ",
  			      cdev->private->dev_id.devno, sch->schid.sch_no);
  		if (cdev->online &&
  		    ccw_device_notify(cdev, CIO_BOXED) != NOTIFY_OK)
  			ccw_device_sched_todo(cdev, CDEV_TODO_UNREG);
  		cdev->private->flags.donotify = 0;
  		break;
  	case DEV_STATE_NOT_OPER:
  		CIO_MSG_EVENT(0, "Device %04x gone on subchannel %04x
  ",
  			      cdev->private->dev_id.devno, sch->schid.sch_no);
  		if (ccw_device_notify(cdev, CIO_GONE) != NOTIFY_OK)
  			ccw_device_sched_todo(cdev, CDEV_TODO_UNREG);
  		else
  			ccw_device_set_disconnected(cdev);
  		cdev->private->flags.donotify = 0;
  		break;
  	case DEV_STATE_DISCONNECTED:
  		CIO_MSG_EVENT(0, "Disconnected device %04x on subchannel "
  			      "%04x
  ", cdev->private->dev_id.devno,
  			      sch->schid.sch_no);
  		if (ccw_device_notify(cdev, CIO_NO_PATH) != NOTIFY_OK) {
  			cdev->private->state = DEV_STATE_NOT_OPER;
  			ccw_device_sched_todo(cdev, CDEV_TODO_UNREG);
  		} else
  			ccw_device_set_disconnected(cdev);
  		cdev->private->flags.donotify = 0;
  		break;
  	default:
  		break;
  	}
  
  	if (cdev->private->flags.donotify) {
  		cdev->private->flags.donotify = 0;
  		ccw_device_oper_notify(cdev);
  	}
  	wake_up(&cdev->private->wait_q);
  }
  
  /*
   * Start device recognition.
   */
  void ccw_device_recognition(struct ccw_device *cdev)
  {
  	struct subchannel *sch = to_subchannel(cdev->dev.parent);
  
  	/*
  	 * We used to start here with a sense pgid to find out whether a device
  	 * is locked by someone else. Unfortunately, the sense pgid command
  	 * code has other meanings on devices predating the path grouping
  	 * algorithm, so we start with sense id and box the device after an
  	 * timeout (or if sense pgid during path verification detects the device
  	 * is locked, as may happen on newer devices).
  	 */
  	cdev->private->flags.recog_done = 0;
  	cdev->private->state = DEV_STATE_SENSE_ID;
  	if (cio_enable_subchannel(sch, (u32) (addr_t) sch)) {
  		ccw_device_recog_done(cdev, DEV_STATE_NOT_OPER);
  		return;
  	}
  	ccw_device_sense_id_start(cdev);
  }
  
  /*
   * Handle events for states that use the ccw request infrastructure.
   */
  static void ccw_device_request_event(struct ccw_device *cdev, enum dev_event e)
  {
  	switch (e) {
  	case DEV_EVENT_NOTOPER:
  		ccw_request_notoper(cdev);
  		break;
  	case DEV_EVENT_INTERRUPT:
  		ccw_request_handler(cdev);
  		break;
  	case DEV_EVENT_TIMEOUT:
  		ccw_request_timeout(cdev);
  		break;
  	default:
  		break;
  	}
  }
  
  static void ccw_device_report_path_events(struct ccw_device *cdev)
  {
  	struct subchannel *sch = to_subchannel(cdev->dev.parent);
  	int path_event[8];
  	int chp, mask;
  
  	for (chp = 0, mask = 0x80; chp < 8; chp++, mask >>= 1) {
  		path_event[chp] = PE_NONE;
  		if (mask & cdev->private->path_gone_mask & ~(sch->vpm))
  			path_event[chp] |= PE_PATH_GONE;
  		if (mask & cdev->private->path_new_mask & sch->vpm)
  			path_event[chp] |= PE_PATH_AVAILABLE;
  		if (mask & cdev->private->pgid_reset_mask & sch->vpm)
  			path_event[chp] |= PE_PATHGROUP_ESTABLISHED;
  	}
  	if (cdev->online && cdev->drv->path_event)
  		cdev->drv->path_event(cdev, path_event);
  }
  
  static void ccw_device_reset_path_events(struct ccw_device *cdev)
  {
  	cdev->private->path_gone_mask = 0;
  	cdev->private->path_new_mask = 0;
  	cdev->private->pgid_reset_mask = 0;
  }
  
  static void create_fake_irb(struct irb *irb, int type)
  {
  	memset(irb, 0, sizeof(*irb));
  	if (type == FAKE_CMD_IRB) {
  		struct cmd_scsw *scsw = &irb->scsw.cmd;
  		scsw->cc = 1;
  		scsw->fctl = SCSW_FCTL_START_FUNC;
  		scsw->actl = SCSW_ACTL_START_PEND;
  		scsw->stctl = SCSW_STCTL_STATUS_PEND;
  	} else if (type == FAKE_TM_IRB) {
  		struct tm_scsw *scsw = &irb->scsw.tm;
  		scsw->x = 1;
  		scsw->cc = 1;
  		scsw->fctl = SCSW_FCTL_START_FUNC;
  		scsw->actl = SCSW_ACTL_START_PEND;
  		scsw->stctl = SCSW_STCTL_STATUS_PEND;
  	}
  }
  
  void ccw_device_verify_done(struct ccw_device *cdev, int err)
  {
  	struct subchannel *sch;
  
  	sch = to_subchannel(cdev->dev.parent);
  	/* Update schib - pom may have changed. */
  	if (cio_update_schib(sch)) {
  		err = -ENODEV;
  		goto callback;
  	}
  	/* Update lpm with verified path mask. */
  	sch->lpm = sch->vpm;
  	/* Repeat path verification? */
  	if (cdev->private->flags.doverify) {
  		ccw_device_verify_start(cdev);
  		return;
  	}
  callback:
  	switch (err) {
  	case 0:
  		ccw_device_done(cdev, DEV_STATE_ONLINE);
  		/* Deliver fake irb to device driver, if needed. */
  		if (cdev->private->flags.fake_irb) {
  			create_fake_irb(&cdev->private->irb,
  					cdev->private->flags.fake_irb);
  			cdev->private->flags.fake_irb = 0;
  			if (cdev->handler)
  				cdev->handler(cdev, cdev->private->intparm,
  					      &cdev->private->irb);
  			memset(&cdev->private->irb, 0, sizeof(struct irb));
  		}
  		ccw_device_report_path_events(cdev);
  		break;
  	case -ETIME:
  	case -EUSERS:
  		/* Reset oper notify indication after verify error. */
  		cdev->private->flags.donotify = 0;
  		ccw_device_done(cdev, DEV_STATE_BOXED);
  		break;
  	case -EACCES:
  		/* Reset oper notify indication after verify error. */
  		cdev->private->flags.donotify = 0;
  		ccw_device_done(cdev, DEV_STATE_DISCONNECTED);
  		break;
  	default:
  		/* Reset oper notify indication after verify error. */
  		cdev->private->flags.donotify = 0;
  		ccw_device_done(cdev, DEV_STATE_NOT_OPER);
  		break;
  	}
  	ccw_device_reset_path_events(cdev);
  }
  
  /*
   * Get device online.
   */
  int
  ccw_device_online(struct ccw_device *cdev)
  {
  	struct subchannel *sch;
  	int ret;
  
  	if ((cdev->private->state != DEV_STATE_OFFLINE) &&
  	    (cdev->private->state != DEV_STATE_BOXED))
  		return -EINVAL;
  	sch = to_subchannel(cdev->dev.parent);
  	ret = cio_enable_subchannel(sch, (u32)(addr_t)sch);
  	if (ret != 0) {
  		/* Couldn't enable the subchannel for i/o. Sick device. */
  		if (ret == -ENODEV)
  			dev_fsm_event(cdev, DEV_EVENT_NOTOPER);
  		return ret;
  	}
  	/* Start initial path verification. */
  	cdev->private->state = DEV_STATE_VERIFY;
  	ccw_device_verify_start(cdev);
  	return 0;
  }
  
  void
  ccw_device_disband_done(struct ccw_device *cdev, int err)
  {
  	switch (err) {
  	case 0:
  		ccw_device_done(cdev, DEV_STATE_OFFLINE);
  		break;
  	case -ETIME:
  		ccw_device_done(cdev, DEV_STATE_BOXED);
  		break;
  	default:
  		cdev->private->flags.donotify = 0;
  		ccw_device_done(cdev, DEV_STATE_NOT_OPER);
  		break;
  	}
  }
  
  /*
   * Shutdown device.
   */
  int
  ccw_device_offline(struct ccw_device *cdev)
  {
  	struct subchannel *sch;
  
  	/* Allow ccw_device_offline while disconnected. */
  	if (cdev->private->state == DEV_STATE_DISCONNECTED ||
  	    cdev->private->state == DEV_STATE_NOT_OPER) {
  		cdev->private->flags.donotify = 0;
  		ccw_device_done(cdev, DEV_STATE_NOT_OPER);
  		return 0;
  	}
  	if (cdev->private->state == DEV_STATE_BOXED) {
  		ccw_device_done(cdev, DEV_STATE_BOXED);
  		return 0;
  	}
  	if (ccw_device_is_orphan(cdev)) {
  		ccw_device_done(cdev, DEV_STATE_OFFLINE);
  		return 0;
  	}
  	sch = to_subchannel(cdev->dev.parent);
  	if (cio_update_schib(sch))
  		return -ENODEV;
  	if (scsw_actl(&sch->schib.scsw) != 0)
  		return -EBUSY;
  	if (cdev->private->state != DEV_STATE_ONLINE)
  		return -EINVAL;
  	/* Are we doing path grouping? */
  	if (!cdev->private->flags.pgroup) {
  		/* No, set state offline immediately. */
  		ccw_device_done(cdev, DEV_STATE_OFFLINE);
  		return 0;
  	}
  	/* Start Set Path Group commands. */
  	cdev->private->state = DEV_STATE_DISBAND_PGID;
  	ccw_device_disband_start(cdev);
  	return 0;
  }
  
  /*
   * Handle not operational event in non-special state.
   */
  static void ccw_device_generic_notoper(struct ccw_device *cdev,
  				       enum dev_event dev_event)
  {
  	if (ccw_device_notify(cdev, CIO_GONE) != NOTIFY_OK)
  		ccw_device_sched_todo(cdev, CDEV_TODO_UNREG);
  	else
  		ccw_device_set_disconnected(cdev);
  }
  
  /*
   * Handle path verification event in offline state.
   */
  static void ccw_device_offline_verify(struct ccw_device *cdev,
  				      enum dev_event dev_event)
  {
  	struct subchannel *sch = to_subchannel(cdev->dev.parent);
  
  	css_schedule_eval(sch->schid);
  }
  
  /*
   * Handle path verification event.
   */
  static void
  ccw_device_online_verify(struct ccw_device *cdev, enum dev_event dev_event)
  {
  	struct subchannel *sch;
  
  	if (cdev->private->state == DEV_STATE_W4SENSE) {
  		cdev->private->flags.doverify = 1;
  		return;
  	}
  	sch = to_subchannel(cdev->dev.parent);
  	/*
  	 * Since we might not just be coming from an interrupt from the
  	 * subchannel we have to update the schib.
  	 */
  	if (cio_update_schib(sch)) {
  		ccw_device_verify_done(cdev, -ENODEV);
  		return;
  	}
  
  	if (scsw_actl(&sch->schib.scsw) != 0 ||
  	    (scsw_stctl(&sch->schib.scsw) & SCSW_STCTL_STATUS_PEND) ||
  	    (scsw_stctl(&cdev->private->irb.scsw) & SCSW_STCTL_STATUS_PEND)) {
  		/*
  		 * No final status yet or final status not yet delivered
  		 * to the device driver. Can't do path verification now,
  		 * delay until final status was delivered.
  		 */
  		cdev->private->flags.doverify = 1;
  		return;
  	}
  	/* Device is idle, we can do the path verification. */
  	cdev->private->state = DEV_STATE_VERIFY;
  	ccw_device_verify_start(cdev);
  }
  
  /*
   * Handle path verification event in boxed state.
   */
  static void ccw_device_boxed_verify(struct ccw_device *cdev,
  				    enum dev_event dev_event)
  {
  	struct subchannel *sch = to_subchannel(cdev->dev.parent);
  
  	if (cdev->online) {
  		if (cio_enable_subchannel(sch, (u32) (addr_t) sch))
  			ccw_device_done(cdev, DEV_STATE_NOT_OPER);
  		else
  			ccw_device_online_verify(cdev, dev_event);
  	} else
  		css_schedule_eval(sch->schid);
  }
  
  /*
   * Pass interrupt to device driver.
   */
  static int ccw_device_call_handler(struct ccw_device *cdev)
  {
  	unsigned int stctl;
  	int ending_status;
  
  	/*
  	 * we allow for the device action handler if .
  	 *  - we received ending status
  	 *  - the action handler requested to see all interrupts
  	 *  - we received an intermediate status
  	 *  - fast notification was requested (primary status)
  	 *  - unsolicited interrupts
  	 */
  	stctl = scsw_stctl(&cdev->private->irb.scsw);
  	ending_status = (stctl & SCSW_STCTL_SEC_STATUS) ||
  		(stctl == (SCSW_STCTL_ALERT_STATUS | SCSW_STCTL_STATUS_PEND)) ||
  		(stctl == SCSW_STCTL_STATUS_PEND);
  	if (!ending_status &&
  	    !cdev->private->options.repall &&
  	    !(stctl & SCSW_STCTL_INTER_STATUS) &&
  	    !(cdev->private->options.fast &&
  	      (stctl & SCSW_STCTL_PRIM_STATUS)))
  		return 0;
  
  	if (ending_status)
  		ccw_device_set_timeout(cdev, 0);
  
  	if (cdev->handler)
  		cdev->handler(cdev, cdev->private->intparm,
  			      &cdev->private->irb);
  
  	memset(&cdev->private->irb, 0, sizeof(struct irb));
  	return 1;
  }
  
  /*
   * Got an interrupt for a normal io (state online).
   */
  static void
  ccw_device_irq(struct ccw_device *cdev, enum dev_event dev_event)
  {
  	struct irb *irb;
  	int is_cmd;
  
  	irb = this_cpu_ptr(&cio_irb);
  	is_cmd = !scsw_is_tm(&irb->scsw);
  	/* Check for unsolicited interrupt. */
  	if (!scsw_is_solicited(&irb->scsw)) {
  		if (is_cmd && (irb->scsw.cmd.dstat & DEV_STAT_UNIT_CHECK) &&
  		    !irb->esw.esw0.erw.cons) {
  			/* Unit check but no sense data. Need basic sense. */
  			if (ccw_device_do_sense(cdev, irb) != 0)
  				goto call_handler_unsol;
  			memcpy(&cdev->private->irb, irb, sizeof(struct irb));
  			cdev->private->state = DEV_STATE_W4SENSE;
  			cdev->private->intparm = 0;
  			return;
  		}
  call_handler_unsol:
  		if (cdev->handler)
  			cdev->handler (cdev, 0, irb);
  		if (cdev->private->flags.doverify)
  			ccw_device_online_verify(cdev, 0);
  		return;
  	}
  	/* Accumulate status and find out if a basic sense is needed. */
  	ccw_device_accumulate_irb(cdev, irb);
  	if (is_cmd && cdev->private->flags.dosense) {
  		if (ccw_device_do_sense(cdev, irb) == 0) {
  			cdev->private->state = DEV_STATE_W4SENSE;
  		}
  		return;
  	}
  	/* Call the handler. */
  	if (ccw_device_call_handler(cdev) && cdev->private->flags.doverify)
  		/* Start delayed path verification. */
  		ccw_device_online_verify(cdev, 0);
  }
  
  /*
   * Got an timeout in online state.
   */
  static void
  ccw_device_online_timeout(struct ccw_device *cdev, enum dev_event dev_event)
  {
  	int ret;
  
  	ccw_device_set_timeout(cdev, 0);
  	cdev->private->iretry = 255;
  	ret = ccw_device_cancel_halt_clear(cdev);
  	if (ret == -EBUSY) {
  		ccw_device_set_timeout(cdev, 3*HZ);
  		cdev->private->state = DEV_STATE_TIMEOUT_KILL;
  		return;
  	}
  	if (ret)
  		dev_fsm_event(cdev, DEV_EVENT_NOTOPER);
  	else if (cdev->handler)
  		cdev->handler(cdev, cdev->private->intparm,
  			      ERR_PTR(-ETIMEDOUT));
  }
  
  /*
   * Got an interrupt for a basic sense.
   */
  static void
  ccw_device_w4sense(struct ccw_device *cdev, enum dev_event dev_event)
  {
  	struct irb *irb;
  
  	irb = this_cpu_ptr(&cio_irb);
  	/* Check for unsolicited interrupt. */
  	if (scsw_stctl(&irb->scsw) ==
  	    (SCSW_STCTL_STATUS_PEND | SCSW_STCTL_ALERT_STATUS)) {
  		if (scsw_cc(&irb->scsw) == 1)
  			/* Basic sense hasn't started. Try again. */
  			ccw_device_do_sense(cdev, irb);
  		else {
  			CIO_MSG_EVENT(0, "0.%x.%04x: unsolicited "
  				      "interrupt during w4sense...
  ",
  				      cdev->private->dev_id.ssid,
  				      cdev->private->dev_id.devno);
  			if (cdev->handler)
  				cdev->handler (cdev, 0, irb);
  		}
  		return;
  	}
  	/*
  	 * Check if a halt or clear has been issued in the meanwhile. If yes,
  	 * only deliver the halt/clear interrupt to the device driver as if it
  	 * had killed the original request.
  	 */
  	if (scsw_fctl(&irb->scsw) &
  	    (SCSW_FCTL_CLEAR_FUNC | SCSW_FCTL_HALT_FUNC)) {
  		cdev->private->flags.dosense = 0;
  		memset(&cdev->private->irb, 0, sizeof(struct irb));
  		ccw_device_accumulate_irb(cdev, irb);
  		goto call_handler;
  	}
  	/* Add basic sense info to irb. */
  	ccw_device_accumulate_basic_sense(cdev, irb);
  	if (cdev->private->flags.dosense) {
  		/* Another basic sense is needed. */
  		ccw_device_do_sense(cdev, irb);
  		return;
  	}
  call_handler:
  	cdev->private->state = DEV_STATE_ONLINE;
  	/* In case sensing interfered with setting the device online */
  	wake_up(&cdev->private->wait_q);
  	/* Call the handler. */
  	if (ccw_device_call_handler(cdev) && cdev->private->flags.doverify)
  		/* Start delayed path verification. */
  		ccw_device_online_verify(cdev, 0);
  }
  
  static void
  ccw_device_killing_irq(struct ccw_device *cdev, enum dev_event dev_event)
  {
  	ccw_device_set_timeout(cdev, 0);
  	/* Start delayed path verification. */
  	ccw_device_online_verify(cdev, 0);
  	/* OK, i/o is dead now. Call interrupt handler. */
  	if (cdev->handler)
  		cdev->handler(cdev, cdev->private->intparm,
  			      ERR_PTR(-EIO));
  }
  
  static void
  ccw_device_killing_timeout(struct ccw_device *cdev, enum dev_event dev_event)
  {
  	int ret;
  
  	ret = ccw_device_cancel_halt_clear(cdev);
  	if (ret == -EBUSY) {
  		ccw_device_set_timeout(cdev, 3*HZ);
  		return;
  	}
  	/* Start delayed path verification. */
  	ccw_device_online_verify(cdev, 0);
  	if (cdev->handler)
  		cdev->handler(cdev, cdev->private->intparm,
  			      ERR_PTR(-EIO));
  }
  
  void ccw_device_kill_io(struct ccw_device *cdev)
  {
  	int ret;
  
  	cdev->private->iretry = 255;
  	ret = ccw_device_cancel_halt_clear(cdev);
  	if (ret == -EBUSY) {
  		ccw_device_set_timeout(cdev, 3*HZ);
  		cdev->private->state = DEV_STATE_TIMEOUT_KILL;
  		return;
  	}
  	/* Start delayed path verification. */
  	ccw_device_online_verify(cdev, 0);
  	if (cdev->handler)
  		cdev->handler(cdev, cdev->private->intparm,
  			      ERR_PTR(-EIO));
  }
  
  static void
  ccw_device_delay_verify(struct ccw_device *cdev, enum dev_event dev_event)
  {
  	/* Start verification after current task finished. */
  	cdev->private->flags.doverify = 1;
  }
  
  static void
  ccw_device_start_id(struct ccw_device *cdev, enum dev_event dev_event)
  {
  	struct subchannel *sch;
  
  	sch = to_subchannel(cdev->dev.parent);
  	if (cio_enable_subchannel(sch, (u32)(addr_t)sch) != 0)
  		/* Couldn't enable the subchannel for i/o. Sick device. */
  		return;
  	cdev->private->state = DEV_STATE_DISCONNECTED_SENSE_ID;
  	ccw_device_sense_id_start(cdev);
  }
  
  void ccw_device_trigger_reprobe(struct ccw_device *cdev)
  {
  	struct subchannel *sch;
  
  	if (cdev->private->state != DEV_STATE_DISCONNECTED)
  		return;
  
  	sch = to_subchannel(cdev->dev.parent);
  	/* Update some values. */
  	if (cio_update_schib(sch))
  		return;
  	/*
  	 * The pim, pam, pom values may not be accurate, but they are the best
  	 * we have before performing device selection :/
  	 */
  	sch->lpm = sch->schib.pmcw.pam & sch->opm;
  	/*
  	 * Use the initial configuration since we can't be shure that the old
  	 * paths are valid.
  	 */
  	io_subchannel_init_config(sch);
  	if (cio_commit_config(sch))
  		return;
  
  	/* We should also udate ssd info, but this has to wait. */
  	/* Check if this is another device which appeared on the same sch. */
  	if (sch->schib.pmcw.dev != cdev->private->dev_id.devno)
  		css_schedule_eval(sch->schid);
  	else
  		ccw_device_start_id(cdev, 0);
  }
  
  static void ccw_device_disabled_irq(struct ccw_device *cdev,
  				    enum dev_event dev_event)
  {
  	struct subchannel *sch;
  
  	sch = to_subchannel(cdev->dev.parent);
  	/*
  	 * An interrupt in a disabled state means a previous disable was not
  	 * successful - should not happen, but we try to disable again.
  	 */
  	cio_disable_subchannel(sch);
  }
  
  static void
  ccw_device_change_cmfstate(struct ccw_device *cdev, enum dev_event dev_event)
  {
  	retry_set_schib(cdev);
  	cdev->private->state = DEV_STATE_ONLINE;
  	dev_fsm_event(cdev, dev_event);
  }
  
  static void ccw_device_update_cmfblock(struct ccw_device *cdev,
  				       enum dev_event dev_event)
  {
  	cmf_retry_copy_block(cdev);
  	cdev->private->state = DEV_STATE_ONLINE;
  	dev_fsm_event(cdev, dev_event);
  }
  
  static void
  ccw_device_quiesce_done(struct ccw_device *cdev, enum dev_event dev_event)
  {
  	ccw_device_set_timeout(cdev, 0);
  	cdev->private->state = DEV_STATE_NOT_OPER;
  	wake_up(&cdev->private->wait_q);
  }
  
  static void
  ccw_device_quiesce_timeout(struct ccw_device *cdev, enum dev_event dev_event)
  {
  	int ret;
  
  	ret = ccw_device_cancel_halt_clear(cdev);
  	if (ret == -EBUSY) {
  		ccw_device_set_timeout(cdev, HZ/10);
  	} else {
  		cdev->private->state = DEV_STATE_NOT_OPER;
  		wake_up(&cdev->private->wait_q);
  	}
  }
  
  /*
   * No operation action. This is used e.g. to ignore a timeout event in
   * state offline.
   */
  static void
  ccw_device_nop(struct ccw_device *cdev, enum dev_event dev_event)
  {
  }
  
  /*
   * device statemachine
   */
  fsm_func_t *dev_jumptable[NR_DEV_STATES][NR_DEV_EVENTS] = {
  	[DEV_STATE_NOT_OPER] = {
  		[DEV_EVENT_NOTOPER]	= ccw_device_nop,
  		[DEV_EVENT_INTERRUPT]	= ccw_device_disabled_irq,
  		[DEV_EVENT_TIMEOUT]	= ccw_device_nop,
  		[DEV_EVENT_VERIFY]	= ccw_device_nop,
  	},
  	[DEV_STATE_SENSE_PGID] = {
  		[DEV_EVENT_NOTOPER]	= ccw_device_request_event,
  		[DEV_EVENT_INTERRUPT]	= ccw_device_request_event,
  		[DEV_EVENT_TIMEOUT]	= ccw_device_request_event,
  		[DEV_EVENT_VERIFY]	= ccw_device_nop,
  	},
  	[DEV_STATE_SENSE_ID] = {
  		[DEV_EVENT_NOTOPER]	= ccw_device_request_event,
  		[DEV_EVENT_INTERRUPT]	= ccw_device_request_event,
  		[DEV_EVENT_TIMEOUT]	= ccw_device_request_event,
  		[DEV_EVENT_VERIFY]	= ccw_device_nop,
  	},
  	[DEV_STATE_OFFLINE] = {
  		[DEV_EVENT_NOTOPER]	= ccw_device_generic_notoper,
  		[DEV_EVENT_INTERRUPT]	= ccw_device_disabled_irq,
  		[DEV_EVENT_TIMEOUT]	= ccw_device_nop,
  		[DEV_EVENT_VERIFY]	= ccw_device_offline_verify,
  	},
  	[DEV_STATE_VERIFY] = {
  		[DEV_EVENT_NOTOPER]	= ccw_device_request_event,
  		[DEV_EVENT_INTERRUPT]	= ccw_device_request_event,
  		[DEV_EVENT_TIMEOUT]	= ccw_device_request_event,
  		[DEV_EVENT_VERIFY]	= ccw_device_delay_verify,
  	},
  	[DEV_STATE_ONLINE] = {
  		[DEV_EVENT_NOTOPER]	= ccw_device_generic_notoper,
  		[DEV_EVENT_INTERRUPT]	= ccw_device_irq,
  		[DEV_EVENT_TIMEOUT]	= ccw_device_online_timeout,
  		[DEV_EVENT_VERIFY]	= ccw_device_online_verify,
  	},
  	[DEV_STATE_W4SENSE] = {
  		[DEV_EVENT_NOTOPER]	= ccw_device_generic_notoper,
  		[DEV_EVENT_INTERRUPT]	= ccw_device_w4sense,
  		[DEV_EVENT_TIMEOUT]	= ccw_device_nop,
  		[DEV_EVENT_VERIFY]	= ccw_device_online_verify,
  	},
  	[DEV_STATE_DISBAND_PGID] = {
  		[DEV_EVENT_NOTOPER]	= ccw_device_request_event,
  		[DEV_EVENT_INTERRUPT]	= ccw_device_request_event,
  		[DEV_EVENT_TIMEOUT]	= ccw_device_request_event,
  		[DEV_EVENT_VERIFY]	= ccw_device_nop,
  	},
  	[DEV_STATE_BOXED] = {
  		[DEV_EVENT_NOTOPER]	= ccw_device_generic_notoper,
  		[DEV_EVENT_INTERRUPT]	= ccw_device_nop,
  		[DEV_EVENT_TIMEOUT]	= ccw_device_nop,
  		[DEV_EVENT_VERIFY]	= ccw_device_boxed_verify,
  	},
  	/* states to wait for i/o completion before doing something */
  	[DEV_STATE_TIMEOUT_KILL] = {
  		[DEV_EVENT_NOTOPER]	= ccw_device_generic_notoper,
  		[DEV_EVENT_INTERRUPT]	= ccw_device_killing_irq,
  		[DEV_EVENT_TIMEOUT]	= ccw_device_killing_timeout,
  		[DEV_EVENT_VERIFY]	= ccw_device_nop, //FIXME
  	},
  	[DEV_STATE_QUIESCE] = {
  		[DEV_EVENT_NOTOPER]	= ccw_device_quiesce_done,
  		[DEV_EVENT_INTERRUPT]	= ccw_device_quiesce_done,
  		[DEV_EVENT_TIMEOUT]	= ccw_device_quiesce_timeout,
  		[DEV_EVENT_VERIFY]	= ccw_device_nop,
  	},
  	/* special states for devices gone not operational */
  	[DEV_STATE_DISCONNECTED] = {
  		[DEV_EVENT_NOTOPER]	= ccw_device_nop,
  		[DEV_EVENT_INTERRUPT]	= ccw_device_start_id,
  		[DEV_EVENT_TIMEOUT]	= ccw_device_nop,
  		[DEV_EVENT_VERIFY]	= ccw_device_start_id,
  	},
  	[DEV_STATE_DISCONNECTED_SENSE_ID] = {
  		[DEV_EVENT_NOTOPER]	= ccw_device_request_event,
  		[DEV_EVENT_INTERRUPT]	= ccw_device_request_event,
  		[DEV_EVENT_TIMEOUT]	= ccw_device_request_event,
  		[DEV_EVENT_VERIFY]	= ccw_device_nop,
  	},
  	[DEV_STATE_CMFCHANGE] = {
  		[DEV_EVENT_NOTOPER]	= ccw_device_change_cmfstate,
  		[DEV_EVENT_INTERRUPT]	= ccw_device_change_cmfstate,
  		[DEV_EVENT_TIMEOUT]	= ccw_device_change_cmfstate,
  		[DEV_EVENT_VERIFY]	= ccw_device_change_cmfstate,
  	},
  	[DEV_STATE_CMFUPDATE] = {
  		[DEV_EVENT_NOTOPER]	= ccw_device_update_cmfblock,
  		[DEV_EVENT_INTERRUPT]	= ccw_device_update_cmfblock,
  		[DEV_EVENT_TIMEOUT]	= ccw_device_update_cmfblock,
  		[DEV_EVENT_VERIFY]	= ccw_device_update_cmfblock,
  	},
  	[DEV_STATE_STEAL_LOCK] = {
  		[DEV_EVENT_NOTOPER]	= ccw_device_request_event,
  		[DEV_EVENT_INTERRUPT]	= ccw_device_request_event,
  		[DEV_EVENT_TIMEOUT]	= ccw_device_request_event,
  		[DEV_EVENT_VERIFY]	= ccw_device_nop,
  	},
  };
  
  EXPORT_SYMBOL_GPL(ccw_device_set_timeout);