/*

   * Copyright IBM Corp. 2000, 2009

   * Author(s): Utz Bacher <utz.bacher@de.ibm.com>
   *	      Cornelia Huck <cornelia.huck@de.ibm.com>
   *	      Jan Glauber <jang@linux.vnet.ibm.com>
   */
  #include <linux/io.h>

  #include <linux/slab.h>

  #include <linux/kernel_stat.h>

  #include <linux/atomic.h>

  #include <asm/debug.h>
  #include <asm/qdio.h>
  #include <asm/airq.h>
  #include <asm/isc.h>
  
  #include "cio.h"
  #include "ioasm.h"
  #include "qdio.h"
  #include "qdio_debug.h"

  
  /*
   * Restriction: only 63 iqdio subchannels would have its own indicator,
   * after that, subsequent subchannels share one indicator
   */
  #define TIQDIO_NR_NONSHARED_IND		63
  #define TIQDIO_NR_INDICATORS		(TIQDIO_NR_NONSHARED_IND + 1)

  #define TIQDIO_SHARED_IND		63
  
  /* device state change indicators */
  struct indicator_t {
  	u32 ind;	/* u32 because of compare-and-swap performance */
  	atomic_t count; /* use count, 0 or 1 for non-shared indicators */
  };

  
  /* list of thin interrupt input queues */
  static LIST_HEAD(tiq_list);

  static DEFINE_MUTEX(tiq_list_lock);

  /* Adapter interrupt definitions */
  static void tiqdio_thinint_handler(struct airq_struct *airq);
  
  static struct airq_struct tiqdio_airq = {
  	.handler = tiqdio_thinint_handler,
  	.isc = QDIO_AIRQ_ISC,
  };

  static struct indicator_t *q_indicators;

  u64 last_ai_time;

  /* returns addr for the device state change indicator */
  static u32 *get_indicator(void)
  {
  	int i;
  
  	for (i = 0; i < TIQDIO_NR_NONSHARED_IND; i++)
  		if (!atomic_read(&q_indicators[i].count)) {
  			atomic_set(&q_indicators[i].count, 1);
  			return &q_indicators[i].ind;
  		}
  
  	/* use the shared indicator */
  	atomic_inc(&q_indicators[TIQDIO_SHARED_IND].count);
  	return &q_indicators[TIQDIO_SHARED_IND].ind;
  }
  
  static void put_indicator(u32 *addr)
  {
  	int i;
  
  	if (!addr)
  		return;
  	i = ((unsigned long)addr - (unsigned long)q_indicators) /
  		sizeof(struct indicator_t);
  	atomic_dec(&q_indicators[i].count);
  }
  
  void tiqdio_add_input_queues(struct qdio_irq *irq_ptr)
  {

  	mutex_lock(&tiq_list_lock);

  	list_add_rcu(&irq_ptr->input_qs[0]->entry, &tiq_list);

  	mutex_unlock(&tiq_list_lock);

  	xchg(irq_ptr->dsci, 1 << 7);

  }

  void tiqdio_remove_input_queues(struct qdio_irq *irq_ptr)
  {
  	struct qdio_q *q;

  	q = irq_ptr->input_qs[0];
  	/* if establish triggered an error */
  	if (!q || !q->entry.prev || !q->entry.next)
  		return;

  	mutex_lock(&tiq_list_lock);
  	list_del_rcu(&q->entry);
  	mutex_unlock(&tiq_list_lock);
  	synchronize_rcu();

  }

  static inline int has_multiple_inq_on_dsci(struct qdio_irq *irq_ptr)
  {
  	return irq_ptr->nr_input_qs > 1;
  }
  
  static inline int references_shared_dsci(struct qdio_irq *irq_ptr)
  {
  	return irq_ptr->dsci == &q_indicators[TIQDIO_SHARED_IND].ind;
  }
  
  static inline int shared_ind(struct qdio_irq *irq_ptr)
  {
  	return references_shared_dsci(irq_ptr) ||
  		has_multiple_inq_on_dsci(irq_ptr);
  }
  
  void clear_nonshared_ind(struct qdio_irq *irq_ptr)
  {
  	if (!is_thinint_irq(irq_ptr))
  		return;
  	if (shared_ind(irq_ptr))
  		return;
  	xchg(irq_ptr->dsci, 0);
  }
  
  int test_nonshared_ind(struct qdio_irq *irq_ptr)
  {
  	if (!is_thinint_irq(irq_ptr))
  		return 0;
  	if (shared_ind(irq_ptr))
  		return 0;
  	if (*irq_ptr->dsci)
  		return 1;
  	else
  		return 0;
  }

  static inline u32 clear_shared_ind(void)

  {

  	if (!atomic_read(&q_indicators[TIQDIO_SHARED_IND].count))
  		return 0;
  	return xchg(&q_indicators[TIQDIO_SHARED_IND].ind, 0);

  }

  static inline void tiqdio_call_inq_handlers(struct qdio_irq *irq)
  {
  	struct qdio_q *q;
  	int i;
  
  	for_each_input_queue(irq, q, i) {
  		if (!references_shared_dsci(irq) &&
  		    has_multiple_inq_on_dsci(irq))
  			xchg(q->irq_ptr->dsci, 0);
  
  		if (q->u.in.queue_start_poll) {
  			/* skip if polling is enabled or already in work */
  			if (test_and_set_bit(QDIO_QUEUE_IRQS_DISABLED,
  					     &q->u.in.queue_irq_state)) {
  				qperf_inc(q, int_discarded);
  				continue;
  			}
  
  			/* avoid dsci clear here, done after processing */
  			q->u.in.queue_start_poll(q->irq_ptr->cdev, q->nr,
  						 q->irq_ptr->int_parm);
  		} else {

  			if (!shared_ind(q->irq_ptr))

  				xchg(q->irq_ptr->dsci, 0);
  
  			/*
  			 * Call inbound processing but not directly
  			 * since that could starve other thinint queues.
  			 */
  			tasklet_schedule(&q->tasklet);
  		}
  	}
  }

  /**
   * tiqdio_thinint_handler - thin interrupt handler for qdio

   * @alsi: pointer to adapter local summary indicator
   * @data: NULL

   */

  static void tiqdio_thinint_handler(struct airq_struct *airq)

  {

  	u32 si_used = clear_shared_ind();

  	struct qdio_q *q;

  	last_ai_time = S390_lowcore.int_clock;

  	inc_irq_stat(IRQIO_QAI);

  	/* protect tiq_list entries, only changed in activate or shutdown */
  	rcu_read_lock();

  	/* check for work on all inbound thinint queues */

  	list_for_each_entry_rcu(q, &tiq_list, entry) {

  		struct qdio_irq *irq;

  		/* only process queues from changed sets */

  		irq = q->irq_ptr;
  		if (unlikely(references_shared_dsci(irq))) {

  			if (!si_used)
  				continue;

  		} else if (!*irq->dsci)

  			continue;

  		tiqdio_call_inq_handlers(irq);

  		qperf_inc(q, adapter_int);
  	}

  	rcu_read_unlock();

  }
  
  static int set_subchannel_ind(struct qdio_irq *irq_ptr, int reset)
  {

  	struct chsc_scssc_area *scssc = (void *)irq_ptr->chsc_page;
  	u64 summary_indicator_addr, subchannel_indicator_addr;

  	int rc;

  	if (reset) {

  		summary_indicator_addr = 0;
  		subchannel_indicator_addr = 0;

  	} else {

  		summary_indicator_addr = virt_to_phys(tiqdio_airq.lsi_ptr);

  		subchannel_indicator_addr = virt_to_phys(irq_ptr->dsci);

  	}

  	rc = chsc_sadc(irq_ptr->schid, scssc, summary_indicator_addr,
  		       subchannel_indicator_addr);

  	if (rc) {

  		DBF_ERROR("%4x SSI r:%4x", irq_ptr->schid.sch_no,

  			  scssc->response.code);
  		goto out;

  	}

  	DBF_EVENT("setscind");

  	DBF_HEX(&summary_indicator_addr, sizeof(summary_indicator_addr));
  	DBF_HEX(&subchannel_indicator_addr, sizeof(subchannel_indicator_addr));
  out:
  	return rc;

  }
  
  /* allocate non-shared indicators and shared indicator */
  int __init tiqdio_allocate_memory(void)
  {
  	q_indicators = kzalloc(sizeof(struct indicator_t) * TIQDIO_NR_INDICATORS,
  			     GFP_KERNEL);
  	if (!q_indicators)
  		return -ENOMEM;
  	return 0;
  }
  
  void tiqdio_free_memory(void)
  {
  	kfree(q_indicators);
  }
  
  int __init tiqdio_register_thinints(void)
  {

  	int rc;
  
  	rc = register_adapter_interrupt(&tiqdio_airq);
  	if (rc) {
  		DBF_EVENT("RTI:%x", rc);
  		return rc;

  	}
  	return 0;
  }
  
  int qdio_establish_thinint(struct qdio_irq *irq_ptr)
  {
  	if (!is_thinint_irq(irq_ptr))
  		return 0;

  	return set_subchannel_ind(irq_ptr, 0);
  }
  
  void qdio_setup_thinint(struct qdio_irq *irq_ptr)
  {
  	if (!is_thinint_irq(irq_ptr))
  		return;
  	irq_ptr->dsci = get_indicator();

  	DBF_HEX(&irq_ptr->dsci, sizeof(void *));

  }
  
  void qdio_shutdown_thinint(struct qdio_irq *irq_ptr)
  {
  	if (!is_thinint_irq(irq_ptr))
  		return;
  
  	/* reset adapter interrupt indicators */

  	set_subchannel_ind(irq_ptr, 1);

  	put_indicator(irq_ptr->dsci);

  }
  
  void __exit tiqdio_unregister_thinints(void)
  {

  	WARN_ON(!list_empty(&tiq_list));

  	unregister_adapter_interrupt(&tiqdio_airq);

  }