source: mainline/kernel/generic/src/ddi/irq.c@ 24abb85d

/*
 * 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 have 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 mode.  However, the
 * hash index is computed only from inr. Moreover, if mode is IRQ_HT_MODE_CLAIM,
 * the match is based also on the return value of the claim(). Otherwise the
 * the keys do not match.
 */

#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;

/**
 * Hash table operations for cases when we know that there will be collisions
 * between different keys.
 */
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,
};

/**
 * 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 size_t irq_lin_hash(sysarg_t *key);
static bool irq_lin_compare(sysarg_t *key, size_t keys, link_t *item);
static void irq_lin_remove(link_t *item);

static hash_table_operations_t irq_lin_ops = {
        .hash = irq_lin_hash,
        .compare = irq_lin_compare,
        .remove_callback = irq_lin_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 chains in the hash table.
 *
 */
void irq_init(size_t inrs, size_t chains)
{
        buckets = chains;
        last_inr = inrs - 1;

        /*
         * 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, sizeof(irq_t), 0);
        link_initialize(&irq->link);
        irq_spinlock_initialize(&irq->lock, "irq.lock");
        link_initialize(&irq->notif_cfg.link);
        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.
 *
 * This function computes hash index into the IRQ hash table for which there can
 * be collisions between different INRs.
 *
 * The mode is not used to compute the hash.
 *
 * @param key The first of the keys is inr and the second is mode.
 *
 * @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.
 *
 * 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 devices. So the explicit check for inr match
 * must be done.  Second, 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);
}

/** 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 mode.
 *
 * @return Index into the hash table.
 *
 */
size_t irq_lin_hash(sysarg_t key[])
{
        inr_t inr = (inr_t) key[IRQ_HT_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 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_lin_compare(sysarg_t key[], size_t keys, link_t *item)
{
        irq_t *irq = list_get_instance(item, irq_t, link);
        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->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_lin_remove(link_t *lnk)
{
        irq_t *irq __attribute__((unused))
            = hash_table_get_instance(lnk, irq_t, link);
        irq_spinlock_unlock(&irq->lock, false);
}

/** @}
 */