/*
   * Support for virtual IRQ subgroups.
   *
   * Copyright (C) 2010  Paul Mundt
   *
   * This file is subject to the terms and conditions of the GNU General Public
   * License.  See the file "COPYING" in the main directory of this archive
   * for more details.
   */
  #define pr_fmt(fmt) "intc: " fmt
  
  #include <linux/slab.h>
  #include <linux/irq.h>
  #include <linux/list.h>
  #include <linux/radix-tree.h>
  #include <linux/spinlock.h>
  #include <linux/export.h>
  #include "internals.h"
  
  static struct intc_map_entry intc_irq_xlate[INTC_NR_IRQS];
  
  struct intc_virq_list {
  	unsigned int irq;
  	struct intc_virq_list *next;
  };
  
  #define for_each_virq(entry, head) \
  	for (entry = head; entry; entry = entry->next)
  
  /*
   * Tags for the radix tree
   */
  #define INTC_TAG_VIRQ_NEEDS_ALLOC	0
  
  void intc_irq_xlate_set(unsigned int irq, intc_enum id, struct intc_desc_int *d)
  {
  	unsigned long flags;
  
  	raw_spin_lock_irqsave(&intc_big_lock, flags);
  	intc_irq_xlate[irq].enum_id = id;
  	intc_irq_xlate[irq].desc = d;
  	raw_spin_unlock_irqrestore(&intc_big_lock, flags);
  }
  
  struct intc_map_entry *intc_irq_xlate_get(unsigned int irq)
  {
  	return intc_irq_xlate + irq;
  }
  
  int intc_irq_lookup(const char *chipname, intc_enum enum_id)
  {
  	struct intc_map_entry *ptr;
  	struct intc_desc_int *d;
  	int irq = -1;
  
  	list_for_each_entry(d, &intc_list, list) {
  		int tagged;
  
  		if (strcmp(d->chip.name, chipname) != 0)
  			continue;
  
  		/*
  		 * Catch early lookups for subgroup VIRQs that have not
  		 * yet been allocated an IRQ. This already includes a
  		 * fast-path out if the tree is untagged, so there is no
  		 * need to explicitly test the root tree.
  		 */
  		tagged = radix_tree_tag_get(&d->tree, enum_id,
  					    INTC_TAG_VIRQ_NEEDS_ALLOC);
  		if (unlikely(tagged))
  			break;
  
  		ptr = radix_tree_lookup(&d->tree, enum_id);
  		if (ptr) {
  			irq = ptr - intc_irq_xlate;
  			break;
  		}
  	}
  
  	return irq;
  }
  EXPORT_SYMBOL_GPL(intc_irq_lookup);
  
  static int add_virq_to_pirq(unsigned int irq, unsigned int virq)
  {
  	struct intc_virq_list *entry;
  	struct intc_virq_list **last = NULL;
  
  	/* scan for duplicates */
  	for_each_virq(entry, irq_get_handler_data(irq)) {
  		if (entry->irq == virq)
  			return 0;
  		last = &entry->next;
  	}
  
  	entry = kzalloc(sizeof(struct intc_virq_list), GFP_ATOMIC);
  	if (!entry) {
  		pr_err("can't allocate VIRQ mapping for %d
  ", virq);
  		return -ENOMEM;
  	}
  
  	entry->irq = virq;
  
  	if (last)
  		*last = entry;
  	else
  		irq_set_handler_data(irq, entry);
  
  	return 0;
  }
  
  static void intc_virq_handler(struct irq_desc *desc)
  {
  	unsigned int irq = irq_desc_get_irq(desc);
  	struct irq_data *data = irq_desc_get_irq_data(desc);
  	struct irq_chip *chip = irq_data_get_irq_chip(data);
  	struct intc_virq_list *entry, *vlist = irq_data_get_irq_handler_data(data);
  	struct intc_desc_int *d = get_intc_desc(irq);
  
  	chip->irq_mask_ack(data);
  
  	for_each_virq(entry, vlist) {
  		unsigned long addr, handle;
  		struct irq_desc *vdesc = irq_to_desc(entry->irq);
  
  		if (vdesc) {
  			handle = (unsigned long)irq_desc_get_handler_data(vdesc);
  			addr = INTC_REG(d, _INTC_ADDR_E(handle), 0);
  			if (intc_reg_fns[_INTC_FN(handle)](addr, handle, 0))
  				generic_handle_irq_desc(vdesc);
  		}
  	}
  
  	chip->irq_unmask(data);
  }
  
  static unsigned long __init intc_subgroup_data(struct intc_subgroup *subgroup,
  					       struct intc_desc_int *d,
  					       unsigned int index)
  {
  	unsigned int fn = REG_FN_TEST_BASE + (subgroup->reg_width >> 3) - 1;
  
  	return _INTC_MK(fn, MODE_ENABLE_REG, intc_get_reg(d, subgroup->reg),
  			0, 1, (subgroup->reg_width - 1) - index);
  }
  
  static void __init intc_subgroup_init_one(struct intc_desc *desc,
  					  struct intc_desc_int *d,
  					  struct intc_subgroup *subgroup)
  {
  	struct intc_map_entry *mapped;
  	unsigned int pirq;
  	unsigned long flags;
  	int i;
  
  	mapped = radix_tree_lookup(&d->tree, subgroup->parent_id);
  	if (!mapped) {
  		WARN_ON(1);
  		return;
  	}
  
  	pirq = mapped - intc_irq_xlate;
  
  	raw_spin_lock_irqsave(&d->lock, flags);
  
  	for (i = 0; i < ARRAY_SIZE(subgroup->enum_ids); i++) {
  		struct intc_subgroup_entry *entry;
  		int err;
  
  		if (!subgroup->enum_ids[i])
  			continue;
  
  		entry = kmalloc(sizeof(*entry), GFP_NOWAIT);
  		if (!entry)
  			break;
  
  		entry->pirq = pirq;
  		entry->enum_id = subgroup->enum_ids[i];
  		entry->handle = intc_subgroup_data(subgroup, d, i);
  
  		err = radix_tree_insert(&d->tree, entry->enum_id, entry);
  		if (unlikely(err < 0))
  			break;
  
  		radix_tree_tag_set(&d->tree, entry->enum_id,
  				   INTC_TAG_VIRQ_NEEDS_ALLOC);
  	}
  
  	raw_spin_unlock_irqrestore(&d->lock, flags);
  }
  
  void __init intc_subgroup_init(struct intc_desc *desc, struct intc_desc_int *d)
  {
  	int i;
  
  	if (!desc->hw.subgroups)
  		return;
  
  	for (i = 0; i < desc->hw.nr_subgroups; i++)
  		intc_subgroup_init_one(desc, d, desc->hw.subgroups + i);
  }
  
  static void __init intc_subgroup_map(struct intc_desc_int *d)
  {
  	struct intc_subgroup_entry *entries[32];
  	unsigned long flags;
  	unsigned int nr_found;
  	int i;
  
  	raw_spin_lock_irqsave(&d->lock, flags);
  
  restart:
  	nr_found = radix_tree_gang_lookup_tag_slot(&d->tree,
  			(void ***)entries, 0, ARRAY_SIZE(entries),
  			INTC_TAG_VIRQ_NEEDS_ALLOC);
  
  	for (i = 0; i < nr_found; i++) {
  		struct intc_subgroup_entry *entry;
  		int irq;
  
  		entry = radix_tree_deref_slot((void **)entries[i]);
  		if (unlikely(!entry))
  			continue;
  		if (radix_tree_deref_retry(entry))
  			goto restart;
  
  		irq = irq_alloc_desc(numa_node_id());
  		if (unlikely(irq < 0)) {
  			pr_err("no more free IRQs, bailing..
  ");
  			break;
  		}
  
  		activate_irq(irq);
  
  		pr_info("Setting up a chained VIRQ from %d -> %d
  ",
  			irq, entry->pirq);
  
  		intc_irq_xlate_set(irq, entry->enum_id, d);
  
  		irq_set_chip_and_handler_name(irq, irq_get_chip(entry->pirq),
  					      handle_simple_irq, "virq");
  		irq_set_chip_data(irq, irq_get_chip_data(entry->pirq));
  
  		irq_set_handler_data(irq, (void *)entry->handle);
  
  		/*
  		 * Set the virtual IRQ as non-threadable.
  		 */
  		irq_set_nothread(irq);
  
  		/* Set handler data before installing the handler */
  		add_virq_to_pirq(entry->pirq, irq);
  		irq_set_chained_handler(entry->pirq, intc_virq_handler);
  
  		radix_tree_tag_clear(&d->tree, entry->enum_id,
  				     INTC_TAG_VIRQ_NEEDS_ALLOC);
  		radix_tree_replace_slot((void **)entries[i],
  					&intc_irq_xlate[irq]);
  	}
  
  	raw_spin_unlock_irqrestore(&d->lock, flags);
  }
  
  void __init intc_finalize(void)
  {
  	struct intc_desc_int *d;
  
  	list_for_each_entry(d, &intc_list, list)
  		if (radix_tree_tagged(&d->tree, INTC_TAG_VIRQ_NEEDS_ALLOC))
  			intc_subgroup_map(d);
  }