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/*

 *  linux/drivers/acorn/scsi/queue.c: queue handling primitives

 *

 *  Copyright (C) 1997-2000 Russell King

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 *  Changelog:

 *   15-Sep-1997 RMK    Created.

 *   11-Oct-1997 RMK    Corrected problem with queue_remove_exclude

 *                      not updating internal linked list properly

 *                      (was causing commands to go missing).

 *   30-Aug-2000 RMK    Use Linux list handling and spinlocks

 */

#include <linux/module.h>

#include <linux/blk.h>

#include <linux/kernel.h>

#include <linux/string.h>

#include <linux/slab.h>

#include <linux/spinlock.h>

#include <linux/list.h>

#include <linux/init.h>

#include "../../scsi/scsi.h"

#define DEBUG

typedef struct queue_entry {

        struct list_head   list;

        Scsi_Cmnd          *SCpnt;

#ifdef DEBUG

        unsigned long      magic;

#endif

} QE_t;

#ifdef DEBUG

#define QUEUE_MAGIC_FREE        0xf7e1c9a3

#define QUEUE_MAGIC_USED        0xf7e1cc33

#define SET_MAGIC(q,m)  ((q)->magic = (m))

#define BAD_MAGIC(q,m)  ((q)->magic != (m))

#else

#define SET_MAGIC(q,m)  do { } while (0)

#define BAD_MAGIC(q,m)  (0)

#endif

#include "queue.h"

#define NR_QE   32

/*

 * Function: void queue_initialise (Queue_t *queue)

 * Purpose : initialise a queue

 * Params  : queue - queue to initialise

 */

int queue_initialise (Queue_t *queue)

{

        unsigned int nqueues = NR_QE;

        QE_t *q;

        spin_lock_init(&queue->queue_lock);

        INIT_LIST_HEAD(&queue->head);

        INIT_LIST_HEAD(&queue->free);

        /*

         * If life was easier, then SCpnt would have a

         * host-available list head, and we wouldn't

         * need to keep free lists or allocate this

         * memory.

         */

        queue->alloc = q = kmalloc(sizeof(QE_t) * nqueues, GFP_KERNEL);

        if (q) {

                for (; nqueues; q++, nqueues--) {

                        SET_MAGIC(q, QUEUE_MAGIC_FREE);

                        q->SCpnt = NULL;

                        list_add(&q->list, &queue->free);

                }

        }

        return queue->alloc != NULL;

}

/*

 * Function: void queue_free (Queue_t *queue)

 * Purpose : free a queue

 * Params  : queue - queue to free

 */

void queue_free (Queue_t *queue)

{

        if (!list_empty(&queue->head))

                printk(KERN_WARNING "freeing non-empty queue %p\n", queue);

        if (queue->alloc)

                kfree(queue->alloc);

}

/*

 * Function: int queue_add_cmd(Queue_t *queue, Scsi_Cmnd *SCpnt, int head)

 * Purpose : Add a new command onto a queue, adding REQUEST_SENSE to head.

 * Params  : queue - destination queue

 *           SCpnt - command to add

 *           head  - add command to head of queue

 * Returns : 0 on error, !0 on success

 */

int __queue_add(Queue_t *queue, Scsi_Cmnd *SCpnt, int head)

{

        unsigned long flags;

        struct list_head *l;

        QE_t *q;

        int ret = 0;

        spin_lock_irqsave(&queue->queue_lock, flags);

        if (list_empty(&queue->free))

                goto empty;

        l = queue->free.next;

        list_del(l);

        q = list_entry(l, QE_t, list);

        if (BAD_MAGIC(q, QUEUE_MAGIC_FREE))

                BUG();

        SET_MAGIC(q, QUEUE_MAGIC_USED);

        q->SCpnt = SCpnt;

        if (head)

                list_add(l, &queue->head);

        else

                list_add_tail(l, &queue->head);

        ret = 1;

empty:

        spin_unlock_irqrestore(&queue->queue_lock, flags);

        return ret;

}

static Scsi_Cmnd *__queue_remove(Queue_t *queue, struct list_head *ent)

{

        QE_t *q;

        /*

         * Move the entry from the "used" list onto the "free" list

         */

        list_del(ent);

        q = list_entry(ent, QE_t, list);

        if (BAD_MAGIC(q, QUEUE_MAGIC_USED))

                BUG();

        SET_MAGIC(q, QUEUE_MAGIC_FREE);

        list_add(ent, &queue->free);

        return q->SCpnt;

}

/*

 * Function: Scsi_Cmnd *queue_remove_exclude (queue, exclude)

 * Purpose : remove a SCSI command from a queue

 * Params  : queue   - queue to remove command from

 *           exclude - bit array of target&lun which is busy

 * Returns : Scsi_Cmnd if successful (and a reference), or NULL if no command available

 */

Scsi_Cmnd *queue_remove_exclude(Queue_t *queue, void *exclude)

{

        unsigned long flags;

        struct list_head *l;

        Scsi_Cmnd *SCpnt = NULL;

        spin_lock_irqsave(&queue->queue_lock, flags);

        list_for_each(l, &queue->head) {

                QE_t *q = list_entry(l, QE_t, list);

                if (!test_bit(q->SCpnt->target * 8 + q->SCpnt->lun, exclude)) {

                        SCpnt = __queue_remove(queue, l);

                        break;

                }

        }

        spin_unlock_irqrestore(&queue->queue_lock, flags);

        return SCpnt;

}

/*

 * Function: Scsi_Cmnd *queue_remove (queue)

 * Purpose : removes first SCSI command from a queue

 * Params  : queue   - queue to remove command from

 * Returns : Scsi_Cmnd if successful (and a reference), or NULL if no command available

 */

Scsi_Cmnd *queue_remove(Queue_t *queue)

{

        unsigned long flags;

        Scsi_Cmnd *SCpnt = NULL;

        spin_lock_irqsave(&queue->queue_lock, flags);

        if (!list_empty(&queue->head))

                SCpnt = __queue_remove(queue, queue->head.next);

        spin_unlock_irqrestore(&queue->queue_lock, flags);

        return SCpnt;

}

/*

 * Function: Scsi_Cmnd *queue_remove_tgtluntag (queue, target, lun, tag)

 * Purpose : remove a SCSI command from the queue for a specified target/lun/tag

 * Params  : queue  - queue to remove command from

 *           target - target that we want

 *           lun    - lun on device

 *           tag    - tag on device

 * Returns : Scsi_Cmnd if successful, or NULL if no command satisfies requirements

 */

Scsi_Cmnd *queue_remove_tgtluntag (Queue_t *queue, int target, int lun, int tag)

{

        unsigned long flags;

        struct list_head *l;

        Scsi_Cmnd *SCpnt = NULL;

        spin_lock_irqsave(&queue->queue_lock, flags);

        list_for_each(l, &queue->head) {

                QE_t *q = list_entry(l, QE_t, list);

                if (q->SCpnt->target == target && q->SCpnt->lun == lun &&

                    q->SCpnt->tag == tag) {

                        SCpnt = __queue_remove(queue, l);

                        break;

                }

        }

        spin_unlock_irqrestore(&queue->queue_lock, flags);

        return SCpnt;

}

/*

 * Function: queue_remove_all_target(queue, target)

 * Purpose : remove all SCSI commands from the queue for a specified target

 * Params  : queue  - queue to remove command from

 *           target - target device id

 * Returns : nothing

 */

void queue_remove_all_target(Queue_t *queue, int target)

{

        unsigned long flags;

        struct list_head *l;

        spin_lock_irqsave(&queue->queue_lock, flags);

        list_for_each(l, &queue->head) {

                QE_t *q = list_entry(l, QE_t, list);

                if (q->SCpnt->target == target)

                        __queue_remove(queue, l);

        }

        spin_unlock_irqrestore(&queue->queue_lock, flags);

}

/*

 * Function: int queue_probetgtlun (queue, target, lun)

 * Purpose : check to see if we have a command in the queue for the specified

 *           target/lun.

 * Params  : queue  - queue to look in

 *           target - target we want to probe

 *           lun    - lun on target

 * Returns : 0 if not found, != 0 if found

 */

int queue_probetgtlun (Queue_t *queue, int target, int lun)

{

        unsigned long flags;

        struct list_head *l;

        int found = 0;

        spin_lock_irqsave(&queue->queue_lock, flags);

        list_for_each(l, &queue->head) {

                QE_t *q = list_entry(l, QE_t, list);

                if (q->SCpnt->target == target && q->SCpnt->lun == lun) {

                        found = 1;

                        break;

                }

        }

        spin_unlock_irqrestore(&queue->queue_lock, flags);

        return found;

}

/*

 * Function: int queue_remove_cmd(Queue_t *queue, Scsi_Cmnd *SCpnt)

 * Purpose : remove a specific command from the queues

 * Params  : queue - queue to look in

 *           SCpnt - command to find

 * Returns : 0 if not found

 */

int queue_remove_cmd(Queue_t *queue, Scsi_Cmnd *SCpnt)

{

        unsigned long flags;

        struct list_head *l;

        int found = 0;

        spin_lock_irqsave(&queue->queue_lock, flags);

        list_for_each(l, &queue->head) {

                QE_t *q = list_entry(l, QE_t, list);

                if (q->SCpnt == SCpnt) {

                        __queue_remove(queue, l);

                        found = 1;

                        break;

                }

        }

        spin_unlock_irqrestore(&queue->queue_lock, flags);

        return found;

}

EXPORT_SYMBOL(queue_initialise);

EXPORT_SYMBOL(queue_free);

EXPORT_SYMBOL(__queue_add);

EXPORT_SYMBOL(queue_remove);

EXPORT_SYMBOL(queue_remove_exclude);

EXPORT_SYMBOL(queue_remove_tgtluntag);

EXPORT_SYMBOL(queue_remove_cmd);

EXPORT_SYMBOL(queue_remove_all_target);

EXPORT_SYMBOL(queue_probetgtlun);

MODULE_AUTHOR("Russell King");

MODULE_DESCRIPTION("SCSI command queueing");

MODULE_LICENSE("GPL");