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/*

 * 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 redirector.

 *

 * This file provides means of connecting IRQs with particular

 * devices and logic for dispatching interrupts to IRQ handlers

 * defined by those devices.

 *

 * This code is designed to support:

 * - multiple devices sharing single IRQ

 * - multiple IRQs per signle device

 *

 *

 * Note about architectures.

 *

 * Some architectures has the term IRQ well defined. Examples

 * of such architectures include amd64, ia32 and mips32. Some

 * other architectures, such as sparc64, don't use the term

 * at all. In those cases, we boldly step forward and define what

 * an IRQ is.

 *

 * The implementation is generic enough and still allows the

 * architectures to use the hardware layout effectively.

 * For instance, on amd64 and ia32, where there is only 16

 * IRQs, the irq_hash_table can be optimized to a one-dimensional

 * array. Next, when it is known that the IRQ numbers (aka INR's)

 * are unique, the claim functions can always return IRQ_ACCEPT.

 */

#include <ddi/irq.h>

#include <adt/hash_table.h>

#include <arch/types.h>

#include <typedefs.h>

#include <synch/spinlock.h>

#include <atomic.h>

#include <arch.h>

/**

 * Spinlock protecting the hash table.

 * This lock must be taken only when interrupts are disabled.

 */

SPINLOCK_INITIALIZE(irq_hash_table_lock);

static hash_table_t irq_hash_table;

/**

 * Hash table operations for cases when we know that

 * there will be collisions between different keys.

 */

static index_t irq_ht_hash(unative_t *key);

static bool irq_ht_compare(unative_t *key, count_t keys, link_t *item);

static hash_table_operations_t irq_ht_ops = {

    .hash = irq_ht_hash,

    .compare = irq_ht_compare,

    .remove_callback = NULL     /* not used */

};

/**

 * Hash table operations for cases when we know that

 * there will be no collisions between different keys.

 * However, there might be still collisions among

 * elements with single key (sharing of one IRQ).

 */

static index_t irq_lin_hash(unative_t *key);

static bool irq_lin_compare(unative_t *key, count_t keys, link_t *item);

static hash_table_operations_t irq_lin_ops = {

    .hash = irq_lin_hash,

    .compare = irq_lin_compare,

    .remove_callback = NULL     /* not used */

};

/** Initialize IRQ subsystem.

 *

 * @param inrs Numbers of unique IRQ numbers or INRs.

 * @param chains Number of chains in the hash table.

 */

void irq_init(count_t inrs, count_t chains)

{

    /*

     * Be smart about the choice of the hash table operations.

     * In cases in which inrs equals the requested number of

     * chains (i.e. where there is no collision between

     * different keys), we can use optimized set of operations.

     */

    if (inrs == chains)

        hash_table_create(&irq_hash_table, chains, 1, &irq_lin_ops);

    else

        hash_table_create(&irq_hash_table, chains, 1, &irq_ht_ops);

}

/** Initialize one IRQ structure.

 *

 * @param irq Pointer to the IRQ structure to be initialized.

 *

 */

void irq_initialize(irq_t *irq)

{

    link_initialize(&irq->link);

    spinlock_initialize(&irq->lock, "irq.lock");

    irq->inr = -1;

    irq->devno = -1;

    irq->trigger = 0;

    irq->claim = NULL;

    irq->handler = NULL;

    irq->arg = NULL;

    irq->notif_answerbox = NULL;

    irq->code = NULL;

    atomic_set(&irq->counter, 0);

}

/** Register IRQ for device.

 *

 * The irq structure must be filled with information

 * about the interrupt source and with the claim()

 * function pointer and irq_handler() function pointer.

 *

 * @param irq IRQ structure belonging to a device.

 */

void irq_register(irq_t *irq)

{

    ipl_t ipl;

    ipl = interrupts_disable();

    spinlock_lock(&irq_hash_table_lock);

    hash_table_insert(&irq_hash_table, (void *) &irq->inr, &irq->link);

    spinlock_unlock(&irq_hash_table_lock);

    interrupts_restore(ipl);

}

/** Dispatch the IRQ.

 *

 * @param inr Interrupt number (aka inr or irq).

 *

 * @return IRQ structure of the respective device or NULL.

 */

irq_t *irq_dispatch(inr_t inr)

{

    ipl_t ipl;

    link_t *lnk;

    ipl = interrupts_disable();

    spinlock_lock(&irq_hash_table_lock);

    lnk = hash_table_find(&irq_hash_table, (void *) &inr);

    if (lnk) {

        irq_t *irq;

        irq = hash_table_get_instance(lnk, irq_t, link);

        spinlock_unlock(&irq_hash_table_lock);

        interrupts_restore(ipl);

        return irq;

    }

    spinlock_unlock(&irq_hash_table_lock);

    interrupts_restore(ipl);

    return NULL;   

}

/** Compute hash index for the key.

 *

 * This function computes hash index into

 * the IRQ hash table for which there

 * can be collisions between different

 * INRs.

 *

 * @param key Pointer to INR.

 *

 * @return Index into the hash table.

 */

index_t irq_ht_hash(unative_t *key)

{

    inr_t *inr = (inr_t *) key;

    return *inr % irq_hash_table.entries;

}

/** Compare hash table element with a key.

 *

 * As usually, we do sort of a hack here.

 * Even when the key matches the inr member,

 * we ask the device to either accept

 * or decline to service the interrupt.

 *

 * @param key Pointer to key (i.e. inr).

 * @param keys This is 1.

 * @param item The item to compare the key with.

 *

 * @return True on match or false otherwise.

 */

bool irq_ht_compare(unative_t *key, count_t keys, link_t *item)

{

    irq_t *irq = hash_table_get_instance(item, irq_t, link);

    inr_t *inr = (inr_t *) key;

    bool rv;

    spinlock_lock(&irq->lock);

    rv = ((irq->inr == *inr) && (irq->claim() == IRQ_ACCEPT));

    spinlock_unlock(&irq->lock);

    return rv;

}

/** Compute hash index for the key.

 *

 * This function computes hash index into

 * the IRQ hash table for which there

 * are no collisions between different

 * INRs.

 *

 * @param key INR.

 *

 * @return Index into the hash table.

 */

index_t irq_lin_hash(unative_t *key)

{

    inr_t *inr = (inr_t *) key;

    return *inr;

}

/** Compare hash table element with a key.

 *

 * As usually, we do sort of a hack here.

 * We don't compare the inr member with

 * the key because we know that there are

 * no collision between different keys.

 * We only ask the device to either accept

 * or decline to service the interrupt.

 *

 * @param key Pointer to key (i.e. inr).

 * @param keys This is 1.

 * @param item The item to compare the key with.

 *

 * @return True on match or false otherwise.

 */

bool irq_lin_compare(unative_t *key, count_t keys, link_t *item)

{

    irq_t *irq = list_get_instance(item, irq_t, link);

    bool rv;

    spinlock_lock(&irq->lock);

    rv = (irq->claim() == IRQ_ACCEPT);

    spinlock_unlock(&irq->lock);

    return rv;

}

/** @}

 */