/*
   * Driver for s390 eadm subchannels
   *
   * Copyright IBM Corp. 2012
   * Author(s): Sebastian Ott <sebott@linux.vnet.ibm.com>
   */

  #include <linux/kernel_stat.h>

  #include <linux/completion.h>

  #include <linux/workqueue.h>
  #include <linux/spinlock.h>
  #include <linux/device.h>
  #include <linux/module.h>
  #include <linux/timer.h>
  #include <linux/slab.h>
  #include <linux/list.h>
  
  #include <asm/css_chars.h>
  #include <asm/debug.h>
  #include <asm/isc.h>
  #include <asm/cio.h>
  #include <asm/scsw.h>
  #include <asm/eadm.h>
  
  #include "eadm_sch.h"
  #include "ioasm.h"
  #include "cio.h"
  #include "css.h"
  #include "orb.h"
  
  MODULE_DESCRIPTION("driver for s390 eadm subchannels");
  MODULE_LICENSE("GPL");
  
  #define EADM_TIMEOUT (5 * HZ)
  static DEFINE_SPINLOCK(list_lock);
  static LIST_HEAD(eadm_list);
  
  static debug_info_t *eadm_debug;
  
  #define EADM_LOG(imp, txt) do {					\
  		debug_text_event(eadm_debug, imp, txt);		\
  	} while (0)
  
  static void EADM_LOG_HEX(int level, void *data, int length)
  {

  	if (!debug_level_enabled(eadm_debug, level))

  		return;
  	while (length > 0) {
  		debug_event(eadm_debug, level, data, length);
  		length -= eadm_debug->buf_size;
  		data += eadm_debug->buf_size;
  	}
  }
  
  static void orb_init(union orb *orb)
  {
  	memset(orb, 0, sizeof(union orb));
  	orb->eadm.compat1 = 1;
  	orb->eadm.compat2 = 1;
  	orb->eadm.fmt = 1;
  	orb->eadm.x = 1;
  }
  
  static int eadm_subchannel_start(struct subchannel *sch, struct aob *aob)
  {
  	union orb *orb = &get_eadm_private(sch)->orb;
  	int cc;
  
  	orb_init(orb);
  	orb->eadm.aob = (u32)__pa(aob);
  	orb->eadm.intparm = (u32)(addr_t)sch;
  	orb->eadm.key = PAGE_DEFAULT_KEY >> 4;
  
  	EADM_LOG(6, "start");
  	EADM_LOG_HEX(6, &sch->schid, sizeof(sch->schid));
  
  	cc = ssch(sch->schid, orb);
  	switch (cc) {
  	case 0:
  		sch->schib.scsw.eadm.actl |= SCSW_ACTL_START_PEND;
  		break;
  	case 1:		/* status pending */
  	case 2:		/* busy */
  		return -EBUSY;
  	case 3:		/* not operational */
  		return -ENODEV;
  	}
  	return 0;
  }
  
  static int eadm_subchannel_clear(struct subchannel *sch)
  {
  	int cc;
  
  	cc = csch(sch->schid);
  	if (cc)
  		return -ENODEV;
  
  	sch->schib.scsw.eadm.actl |= SCSW_ACTL_CLEAR_PEND;
  	return 0;
  }
  
  static void eadm_subchannel_timeout(unsigned long data)
  {
  	struct subchannel *sch = (struct subchannel *) data;
  
  	spin_lock_irq(sch->lock);
  	EADM_LOG(1, "timeout");
  	EADM_LOG_HEX(1, &sch->schid, sizeof(sch->schid));
  	if (eadm_subchannel_clear(sch))
  		EADM_LOG(0, "clear failed");
  	spin_unlock_irq(sch->lock);
  }
  
  static void eadm_subchannel_set_timeout(struct subchannel *sch, int expires)
  {
  	struct eadm_private *private = get_eadm_private(sch);
  
  	if (expires == 0) {
  		del_timer(&private->timer);
  		return;
  	}
  	if (timer_pending(&private->timer)) {
  		if (mod_timer(&private->timer, jiffies + expires))
  			return;
  	}
  	private->timer.function = eadm_subchannel_timeout;
  	private->timer.data = (unsigned long) sch;
  	private->timer.expires = jiffies + expires;
  	add_timer(&private->timer);
  }
  
  static void eadm_subchannel_irq(struct subchannel *sch)
  {
  	struct eadm_private *private = get_eadm_private(sch);
  	struct eadm_scsw *scsw = &sch->schib.scsw.eadm;

  	struct irb *irb = this_cpu_ptr(&cio_irb);

  	int error = 0;
  
  	EADM_LOG(6, "irq");
  	EADM_LOG_HEX(6, irb, sizeof(*irb));

  	inc_irq_stat(IRQIO_ADM);

  	if ((scsw->stctl & (SCSW_STCTL_ALERT_STATUS | SCSW_STCTL_STATUS_PEND))
  	    && scsw->eswf == 1 && irb->esw.eadm.erw.r)
  		error = -EIO;
  
  	if (scsw->fctl & SCSW_FCTL_CLEAR_FUNC)
  		error = -ETIMEDOUT;
  
  	eadm_subchannel_set_timeout(sch, 0);
  
  	if (private->state != EADM_BUSY) {
  		EADM_LOG(1, "irq unsol");
  		EADM_LOG_HEX(1, irb, sizeof(*irb));
  		private->state = EADM_NOT_OPER;
  		css_sched_sch_todo(sch, SCH_TODO_EVAL);
  		return;
  	}
  	scm_irq_handler((struct aob *)(unsigned long)scsw->aob, error);
  	private->state = EADM_IDLE;

  
  	if (private->completion)
  		complete(private->completion);

  }
  
  static struct subchannel *eadm_get_idle_sch(void)
  {
  	struct eadm_private *private;
  	struct subchannel *sch;
  	unsigned long flags;
  
  	spin_lock_irqsave(&list_lock, flags);
  	list_for_each_entry(private, &eadm_list, head) {
  		sch = private->sch;
  		spin_lock(sch->lock);
  		if (private->state == EADM_IDLE) {
  			private->state = EADM_BUSY;
  			list_move_tail(&private->head, &eadm_list);
  			spin_unlock(sch->lock);
  			spin_unlock_irqrestore(&list_lock, flags);
  
  			return sch;
  		}
  		spin_unlock(sch->lock);
  	}
  	spin_unlock_irqrestore(&list_lock, flags);
  
  	return NULL;
  }

  int eadm_start_aob(struct aob *aob)

  {
  	struct eadm_private *private;
  	struct subchannel *sch;
  	unsigned long flags;
  	int ret;
  
  	sch = eadm_get_idle_sch();
  	if (!sch)
  		return -EBUSY;
  
  	spin_lock_irqsave(sch->lock, flags);
  	eadm_subchannel_set_timeout(sch, EADM_TIMEOUT);
  	ret = eadm_subchannel_start(sch, aob);
  	if (!ret)
  		goto out_unlock;
  
  	/* Handle start subchannel failure. */
  	eadm_subchannel_set_timeout(sch, 0);
  	private = get_eadm_private(sch);
  	private->state = EADM_NOT_OPER;
  	css_sched_sch_todo(sch, SCH_TODO_EVAL);
  
  out_unlock:
  	spin_unlock_irqrestore(sch->lock, flags);
  
  	return ret;
  }

  EXPORT_SYMBOL_GPL(eadm_start_aob);

  
  static int eadm_subchannel_probe(struct subchannel *sch)
  {
  	struct eadm_private *private;
  	int ret;
  
  	private = kzalloc(sizeof(*private), GFP_KERNEL | GFP_DMA);
  	if (!private)
  		return -ENOMEM;
  
  	INIT_LIST_HEAD(&private->head);
  	init_timer(&private->timer);
  
  	spin_lock_irq(sch->lock);
  	set_eadm_private(sch, private);
  	private->state = EADM_IDLE;
  	private->sch = sch;
  	sch->isc = EADM_SCH_ISC;
  	ret = cio_enable_subchannel(sch, (u32)(unsigned long)sch);
  	if (ret) {
  		set_eadm_private(sch, NULL);
  		spin_unlock_irq(sch->lock);
  		kfree(private);
  		goto out;
  	}
  	spin_unlock_irq(sch->lock);
  
  	spin_lock_irq(&list_lock);
  	list_add(&private->head, &eadm_list);
  	spin_unlock_irq(&list_lock);
  
  	if (dev_get_uevent_suppress(&sch->dev)) {
  		dev_set_uevent_suppress(&sch->dev, 0);
  		kobject_uevent(&sch->dev.kobj, KOBJ_ADD);
  	}
  out:
  	return ret;
  }
  
  static void eadm_quiesce(struct subchannel *sch)
  {

  	struct eadm_private *private = get_eadm_private(sch);
  	DECLARE_COMPLETION_ONSTACK(completion);

  	int ret;

  	spin_lock_irq(sch->lock);
  	if (private->state != EADM_BUSY)
  		goto disable;
  
  	if (eadm_subchannel_clear(sch))
  		goto disable;
  
  	private->completion = &completion;
  	spin_unlock_irq(sch->lock);
  
  	wait_for_completion_io(&completion);
  
  	spin_lock_irq(sch->lock);
  	private->completion = NULL;
  
  disable:
  	eadm_subchannel_set_timeout(sch, 0);

  	do {

  		ret = cio_disable_subchannel(sch);

  	} while (ret == -EBUSY);

  
  	spin_unlock_irq(sch->lock);

  }
  
  static int eadm_subchannel_remove(struct subchannel *sch)
  {
  	struct eadm_private *private = get_eadm_private(sch);
  
  	spin_lock_irq(&list_lock);
  	list_del(&private->head);
  	spin_unlock_irq(&list_lock);
  
  	eadm_quiesce(sch);
  
  	spin_lock_irq(sch->lock);
  	set_eadm_private(sch, NULL);
  	spin_unlock_irq(sch->lock);
  
  	kfree(private);
  
  	return 0;
  }
  
  static void eadm_subchannel_shutdown(struct subchannel *sch)
  {
  	eadm_quiesce(sch);
  }
  
  static int eadm_subchannel_freeze(struct subchannel *sch)
  {
  	return cio_disable_subchannel(sch);
  }
  
  static int eadm_subchannel_restore(struct subchannel *sch)
  {
  	return cio_enable_subchannel(sch, (u32)(unsigned long)sch);
  }
  
  /**
   * eadm_subchannel_sch_event - process subchannel event
   * @sch: subchannel
   * @process: non-zero if function is called in process context
   *
   * An unspecified event occurred for this subchannel. Adjust data according
   * to the current operational state of the subchannel. Return zero when the
   * event has been handled sufficiently or -EAGAIN when this function should
   * be called again in process context.
   */
  static int eadm_subchannel_sch_event(struct subchannel *sch, int process)
  {
  	struct eadm_private *private;
  	unsigned long flags;
  	int ret = 0;
  
  	spin_lock_irqsave(sch->lock, flags);
  	if (!device_is_registered(&sch->dev))
  		goto out_unlock;
  
  	if (work_pending(&sch->todo_work))
  		goto out_unlock;
  
  	if (cio_update_schib(sch)) {
  		css_sched_sch_todo(sch, SCH_TODO_UNREG);
  		goto out_unlock;
  	}
  	private = get_eadm_private(sch);
  	if (private->state == EADM_NOT_OPER)
  		private->state = EADM_IDLE;
  
  out_unlock:
  	spin_unlock_irqrestore(sch->lock, flags);
  
  	return ret;
  }
  
  static struct css_device_id eadm_subchannel_ids[] = {
  	{ .match_flags = 0x1, .type = SUBCHANNEL_TYPE_ADM, },
  	{ /* end of list */ },
  };
  MODULE_DEVICE_TABLE(css, eadm_subchannel_ids);
  
  static struct css_driver eadm_subchannel_driver = {
  	.drv = {
  		.name = "eadm_subchannel",
  		.owner = THIS_MODULE,
  	},
  	.subchannel_type = eadm_subchannel_ids,
  	.irq = eadm_subchannel_irq,
  	.probe = eadm_subchannel_probe,
  	.remove = eadm_subchannel_remove,
  	.shutdown = eadm_subchannel_shutdown,
  	.sch_event = eadm_subchannel_sch_event,
  	.freeze = eadm_subchannel_freeze,
  	.thaw = eadm_subchannel_restore,
  	.restore = eadm_subchannel_restore,
  };

  static int __init eadm_sch_init(void)
  {
  	int ret;
  
  	if (!css_general_characteristics.eadm)
  		return -ENXIO;
  
  	eadm_debug = debug_register("eadm_log", 16, 1, 16);
  	if (!eadm_debug)
  		return -ENOMEM;
  
  	debug_register_view(eadm_debug, &debug_hex_ascii_view);
  	debug_set_level(eadm_debug, 2);
  
  	isc_register(EADM_SCH_ISC);
  	ret = css_driver_register(&eadm_subchannel_driver);
  	if (ret)
  		goto cleanup;

  	return ret;
  
  cleanup:
  	isc_unregister(EADM_SCH_ISC);
  	debug_unregister(eadm_debug);
  	return ret;
  }
  
  static void __exit eadm_sch_exit(void)
  {

  	css_driver_unregister(&eadm_subchannel_driver);
  	isc_unregister(EADM_SCH_ISC);
  	debug_unregister(eadm_debug);
  }
  module_init(eadm_sch_init);
  module_exit(eadm_sch_exit);