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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 dispatcher.

 *

 * 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 single device

 * - multiple instances of the same 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.

 *

 *

 * Note about the irq_hash_table.

 *

 * The hash table is configured to use two keys: inr and devno.

 * However, the hash index is computed only from inr. Moreover,

 * if devno is -1, the match is based on the return value of

 * the claim() function instead of on devno.

 */

#include <ddi/irq.h>

#include <adt/hash_table.h>

#include <mm/slab.h>

#include <arch/types.h>

#include <synch/spinlock.h>

#include <memstr.h>

#include <arch.h>

#define KEY_INR		0

#define KEY_DEVNO	1

/**

 * Spinlock protecting the kernel IRQ hash table.

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

 */

SPINLOCK_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.

 */

SPINLOCK_INITIALIZE(irq_uspace_hash_table_lock);

/** The uspace IRQ hash table. */

hash_table_t irq_uspace_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 */

};

/** Number of buckets in either of the hash tables. */

static count_t buckets;

/** 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)

{

	buckets = 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_uspace_hash_table, chains, 2,

		    &irq_lin_ops);

		hash_table_create(&irq_kernel_hash_table, chains, 2,

		    &irq_lin_ops);

	} else {

		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, 0, sizeof(irq_t));

	link_initialize(&irq->link);

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

	link_initialize(&irq->notif_cfg.link);

	irq->inr = -1;

	irq->devno = -1;

}

/** 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.

 * @return		True on success, false on failure.

 */

void irq_register(irq_t *irq)

{

	ipl_t ipl;

	unative_t key[] = {

		(unative_t) irq->inr,

		(unative_t) irq->devno

	};

	ipl = interrupts_disable();

	spinlock_lock(&irq_kernel_hash_table_lock);

	spinlock_lock(&irq->lock);

	hash_table_insert(&irq_kernel_hash_table, key, &irq->link);

	spinlock_unlock(&irq->lock);	

	spinlock_unlock(&irq_kernel_hash_table_lock);

	interrupts_restore(ipl);

}

/** 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 or NULL.

 */

irq_t *irq_dispatch_and_lock(inr_t inr)

{

	link_t *lnk;

	unative_t key[] = {

		(unative_t) inr,

		(unative_t) -1		/* search will use claim() instead of devno */

	};

	/*

	 * Try uspace handlers first.

	 */

	spinlock_lock(&irq_uspace_hash_table_lock);

	lnk = hash_table_find(&irq_uspace_hash_table, key);

	if (lnk) {

		irq_t *irq;

		irq = hash_table_get_instance(lnk, irq_t, link);

		spinlock_unlock(&irq_uspace_hash_table_lock);

		return irq;

	}

	spinlock_unlock(&irq_uspace_hash_table_lock);

	/*

	 * Fallback to kernel handlers.

	 */

	spinlock_lock(&irq_kernel_hash_table_lock);

	lnk = hash_table_find(&irq_kernel_hash_table, key);

	if (lnk) {

		irq_t *irq;

		irq = hash_table_get_instance(lnk, irq_t, link);

		spinlock_unlock(&irq_kernel_hash_table_lock);

		return irq;

	}

	spinlock_unlock(&irq_kernel_hash_table_lock);

	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.

 *

 * The devno is not used to compute the hash.

 *

 * @param key The first of the keys is inr and the second is devno or -1.

 *

 * @return Index into the hash table.

 */

index_t irq_ht_hash(unative_t key[])

{

	inr_t inr = (inr_t) key[KEY_INR];

	return inr % buckets;

}

/** Compare hash table element with a key.

 *

 * There are two things to note about this function.

 * First, it is used for the more complex architecture setup

 * in which there are way too many interrupt numbers (i.e. inr's)

 * to arrange the hash table so that collisions occur only

 * among same inrs of different devnos. So the explicit check

 * for inr match must be done.

 * Second, if devno is -1, the second key (i.e. devno) is not

 * used for the match and the result of the claim() function

 * is used instead.

 *

 * This function assumes interrupts are already disabled.

 *

 * @param key Keys (i.e. inr and devno).

 * @param keys This is 2.

 * @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[KEY_INR];

	devno_t devno = (devno_t) key[KEY_DEVNO];

	bool rv;

	spinlock_lock(&irq->lock);

	if (devno == -1) {

		/* Invoked by irq_dispatch_and_lock(). */

		rv = ((irq->inr == inr) &&

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

	} else {

		/* Invoked by irq_find_and_lock(). */

		rv = ((irq->inr == inr) && (irq->devno == devno));

	}

	/* unlock only on non-match */

	if (!rv)

		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 The first of the keys is inr and the second is devno or -1.

 *

 * @return Index into the hash table.

 */

index_t irq_lin_hash(unative_t key[])

{

	inr_t inr = (inr_t) key[KEY_INR];

	return inr;

}

/** Compare hash table element with a key.

 *

 * There are two things to note about this function.

 * First, it is used for the less complex architecture setup

 * in which there are not too many interrupt numbers (i.e. inr's)

 * to arrange the hash table so that collisions occur only

 * among same inrs of different devnos. So the explicit check

 * for inr match is not done.

 * Second, if devno is -1, the second key (i.e. devno) is not

 * used for the match and the result of the claim() function

 * is used instead.

 *

 * This function assumes interrupts are already disabled.

 *

 * @param key Keys (i.e. inr and devno).

 * @param keys This is 2.

 * @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);

	devno_t devno = (devno_t) key[KEY_DEVNO];

	bool rv;

	spinlock_lock(&irq->lock);

	if (devno == -1) {

		/* Invoked by irq_dispatch_and_lock() */

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

	} else {

		/* Invoked by irq_find_and_lock() */

		rv = (irq->devno == devno);

	}

	/* unlock only on non-match */

	if (!rv)

		spinlock_unlock(&irq->lock);

	return rv;

}

/** @}

 */