/*
 * Copyright (c) 2006 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup genericddi
 * @{
 */
/**
 * @file
 * @brief IRQ dispatcher
 *
 * This file provides means of connecting IRQs with respective device drivers
 * and logic for dispatching interrupts to IRQ handlers defined by those
 * drivers.
 */

#include <ddi/irq.h>
#include <adt/hash_table.h>
#include <mm/slab.h>
#include <typedefs.h>
#include <synch/spinlock.h>
#include <console/console.h>
#include <interrupt.h>
#include <mem.h>
#include <arch.h>

/** Spinlock protecting the kernel IRQ hash table
 *
 * This lock must be taken only when interrupts are disabled.
 *
 */
IRQ_SPINLOCK_STATIC_INITIALIZE(irq_kernel_hash_table_lock);

/** The kernel IRQ hash table. */
static hash_table_t irq_kernel_hash_table;

/** Spinlock protecting the uspace IRQ hash table
 *
 * This lock must be taken only when interrupts are disabled.
 *
 */
IRQ_SPINLOCK_INITIALIZE(irq_uspace_hash_table_lock);

/** The uspace IRQ hash table */
hash_table_t irq_uspace_hash_table;

static size_t irq_ht_hash(sysarg_t *key);
static bool irq_ht_compare(sysarg_t *key, size_t keys, link_t *item);
static void irq_ht_remove(link_t *item);

static hash_table_operations_t irq_ht_ops = {
	.hash = irq_ht_hash,
	.compare = irq_ht_compare,
	.remove_callback = irq_ht_remove,
};

/** Number of buckets in either of the hash tables */
static size_t buckets;

/** Last valid INR */
inr_t last_inr = 0;

/** Initialize IRQ subsystem
 *
 * @param inrs    Numbers of unique IRQ numbers or INRs.
 * @param chains  Number of buckets in the hash table.
 *
 */
void irq_init(size_t inrs, size_t chains)
{
	buckets = chains;
	last_inr = inrs - 1;

	hash_table_create(&irq_uspace_hash_table, chains, 2, &irq_ht_ops);
	hash_table_create(&irq_kernel_hash_table, chains, 2, &irq_ht_ops);
}

/** Initialize one IRQ structure
 *
 * @param irq  Pointer to the IRQ structure to be initialized.
 *
 */
void irq_initialize(irq_t *irq)
{
	memsetb(irq, sizeof(irq_t), 0);
	link_initialize(&irq->link);
	irq_spinlock_initialize(&irq->lock, "irq.lock");
	irq->inr = -1;
	
	irq_initialize_arch(irq);
}

/** Register IRQ for device
 *
 * The irq structure must be filled with information about the interrupt source
 * and with the claim() function pointer and handler() function pointer.
 *
 * @param irq  IRQ structure belonging to a device.
 *
 */
void irq_register(irq_t *irq)
{
	sysarg_t key[] = {
		[IRQ_HT_KEY_INR] = (sysarg_t) irq->inr,
		[IRQ_HT_KEY_MODE] = (sysarg_t) IRQ_HT_MODE_NO_CLAIM 
	};
	
	irq_spinlock_lock(&irq_kernel_hash_table_lock, true);
	irq_spinlock_lock(&irq->lock, false);
	hash_table_insert(&irq_kernel_hash_table, key, &irq->link);
	irq_spinlock_unlock(&irq->lock, false);
	irq_spinlock_unlock(&irq_kernel_hash_table_lock, true);
}

/** Search and lock the uspace IRQ hash table */
static irq_t *irq_dispatch_and_lock_uspace(inr_t inr)
{
	link_t *lnk;
	sysarg_t key[] = {
		[IRQ_HT_KEY_INR] = (sysarg_t) inr,
		[IRQ_HT_KEY_MODE] = (sysarg_t) IRQ_HT_MODE_CLAIM
	};
	
	irq_spinlock_lock(&irq_uspace_hash_table_lock, false);
	lnk = hash_table_find(&irq_uspace_hash_table, key);
	if (lnk) {
		irq_t *irq = hash_table_get_instance(lnk, irq_t, link);
		irq_spinlock_unlock(&irq_uspace_hash_table_lock, false);
		return irq;
	}
	irq_spinlock_unlock(&irq_uspace_hash_table_lock, false);
	
	return NULL;
}

/** Search and lock the kernel IRQ hash table */
static irq_t *irq_dispatch_and_lock_kernel(inr_t inr)
{
	link_t *lnk;
	sysarg_t key[] = {
		[IRQ_HT_KEY_INR] = (sysarg_t) inr,
		[IRQ_HT_KEY_MODE] = (sysarg_t) IRQ_HT_MODE_CLAIM
	};
	
	irq_spinlock_lock(&irq_kernel_hash_table_lock, false);
	lnk = hash_table_find(&irq_kernel_hash_table, key);
	if (lnk) {
		irq_t *irq = hash_table_get_instance(lnk, irq_t, link);
		irq_spinlock_unlock(&irq_kernel_hash_table_lock, false);
		return irq;
	}
	irq_spinlock_unlock(&irq_kernel_hash_table_lock, false);
	
	return NULL;
}

/** Dispatch the IRQ
 *
 * We assume this function is only called from interrupt context (i.e. that
 * interrupts are disabled prior to this call).
 *
 * This function attempts to lookup a fitting IRQ structure. In case of success,
 * return with interrupts disabled and holding the respective structure.
 *
 * @param inr  Interrupt number (aka inr or irq).
 *
 * @return IRQ structure of the respective device
 * @return NULL if no IRQ structure found
 *
 */
irq_t *irq_dispatch_and_lock(inr_t inr)
{
	/*
	 * If the kernel console override is on, then try first the kernel
	 * handlers and eventually fall back to uspace handlers.
	 *
	 * In the usual case the uspace handlers have precedence.
	 */
	
	if (console_override) {
		irq_t *irq = irq_dispatch_and_lock_kernel(inr);
		if (irq)
			return irq;
		
		return irq_dispatch_and_lock_uspace(inr);
	}
	
	irq_t *irq = irq_dispatch_and_lock_uspace(inr);
	if (irq)
		return irq;
	
	return irq_dispatch_and_lock_kernel(inr);
}

/** Compute hash index for the key
 *
 * @param key  The first of the keys is inr and the second is mode. Only inr is
 *             used to compute the hash.
 *
 * @return Index into the hash table.
 *
 */
size_t irq_ht_hash(sysarg_t key[])
{
	inr_t inr = (inr_t) key[IRQ_HT_KEY_INR];
	return inr % buckets;
}

/** Compare hash table element with a key
 *
 * If mode is IRQ_HT_MODE_CLAIM, the result of the claim() function is used for
 * the match. Otherwise the key does not match.
 *
 * This function assumes interrupts are already disabled.
 *
 * @param key   Keys (i.e. inr and mode).
 * @param keys  This is 2. 
 * @param item  The item to compare the key with.
 *
 * @return True on match
 * @return False on no match
 *
 */
bool irq_ht_compare(sysarg_t key[], size_t keys, link_t *item)
{
	irq_t *irq = hash_table_get_instance(item, irq_t, link);
	inr_t inr = (inr_t) key[IRQ_HT_KEY_INR];
	irq_ht_mode_t mode = (irq_ht_mode_t) key[IRQ_HT_KEY_MODE];
	
	bool rv;
	
	irq_spinlock_lock(&irq->lock, false);
	if (mode == IRQ_HT_MODE_CLAIM) {
		/* Invoked by irq_dispatch_and_lock(). */
		rv = ((irq->inr == inr) && (irq->claim(irq) == IRQ_ACCEPT));
	} else {
		/* Invoked by irq_find_and_lock(). */
		rv = false;
	}
	
	/* unlock only on non-match */
	if (!rv)
		irq_spinlock_unlock(&irq->lock, false);
	
	return rv;
}

/** Unlock IRQ structure after hash_table_remove()
 *
 * @param lnk  Link in the removed and locked IRQ structure.
 */
void irq_ht_remove(link_t *lnk)
{
	irq_t *irq __attribute__((unused))
	    = hash_table_get_instance(lnk, irq_t, link);
	irq_spinlock_unlock(&irq->lock, false);
}

/** @}
 */