drivers/acorn/scsi/queue.c

   1 /*
   2  *  linux/drivers/acorn/scsi/queue.c: queue handling primitives
   3  *
   4  *  Copyright (C) 1997-2000 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  *  Changelog:
  11  *   15-Sep-1997 RMK    Created.
  12  *   11-Oct-1997 RMK    Corrected problem with queue_remove_exclude
  13  *                      not updating internal linked list properly
  14  *                      (was causing commands to go missing).
  15  *   30-Aug-2000 RMK    Use Linux list handling and spinlocks
  16  */
  17 #include <linux/module.h>
  18 #include <linux/blk.h>
  19 #include <linux/kernel.h>
  20 #include <linux/string.h>
  21 #include <linux/slab.h>
  22 #include <linux/spinlock.h>
  23 #include <linux/list.h>
  24 #include <linux/init.h>
  25
  26 #include "../../scsi/scsi.h"
  27
  28 #define DEBUG
  29
  30 typedef struct queue_entry {
  31         struct list_head   list;
  32         Scsi_Cmnd          *SCpnt;
  33 #ifdef DEBUG
  34         unsigned long      magic;
  35 #endif
  36 } QE_t;
  37
  38 #ifdef DEBUG
  39 #define QUEUE_MAGIC_FREE        0xf7e1c9a3
  40 #define QUEUE_MAGIC_USED        0xf7e1cc33
  41
  42 #define SET_MAGIC(q,m)  ((q)->magic = (m))
  43 #define BAD_MAGIC(q,m)  ((q)->magic != (m))
  44 #else
  45 #define SET_MAGIC(q,m)  do { } while (0)
  46 #define BAD_MAGIC(q,m)  (0)
  47 #endif
  48
  49 #include "queue.h"
  50
  51 #define NR_QE   32
  52
  53 /*
  54  * Function: void queue_initialise (Queue_t *queue)
  55  * Purpose : initialise a queue
  56  * Params  : queue - queue to initialise
  57  */
  58 int queue_initialise (Queue_t *queue)
  59 {
  60         unsigned int nqueues = NR_QE;
  61         QE_t *q;
  62
  63         spin_lock_init(&queue->queue_lock);
  64         INIT_LIST_HEAD(&queue->head);
  65         INIT_LIST_HEAD(&queue->free);
  66
  67         /*
  68          * If life was easier, then SCpnt would have a
  69          * host-available list head, and we wouldn't
  70          * need to keep free lists or allocate this
  71          * memory.
  72          */
  73         queue->alloc = q = kmalloc(sizeof(QE_t) * nqueues, GFP_KERNEL);
  74         if (q) {
  75                 for (; nqueues; q++, nqueues--) {
  76                         SET_MAGIC(q, QUEUE_MAGIC_FREE);
  77                         q->SCpnt = NULL;
  78                         list_add(&q->list, &queue->free);
  79                 }
  80         }
  81
  82         return queue->alloc != NULL;
  83 }
  84
  85 /*
  86  * Function: void queue_free (Queue_t *queue)
  87  * Purpose : free a queue
  88  * Params  : queue - queue to free
  89  */
  90 void queue_free (Queue_t *queue)
  91 {
  92         if (!list_empty(&queue->head))
  93                 printk(KERN_WARNING "freeing non-empty queue %p\n", queue);
  94         if (queue->alloc)
  95                 kfree(queue->alloc);
  96 }
  97
  98
  99 /*
 100  * Function: int queue_add_cmd(Queue_t *queue, Scsi_Cmnd *SCpnt, int head)
 101  * Purpose : Add a new command onto a queue, adding REQUEST_SENSE to head.
 102  * Params  : queue - destination queue
 103  *           SCpnt - command to add
 104  *           head  - add command to head of queue
 105  * Returns : 0 on error, !0 on success
 106  */
 107 int __queue_add(Queue_t *queue, Scsi_Cmnd *SCpnt, int head)
 108 {
 109         unsigned long flags;
 110         struct list_head *l;
 111         QE_t *q;
 112         int ret = 0;
 113
 114         spin_lock_irqsave(&queue->queue_lock, flags);
 115         if (list_empty(&queue->free))
 116                 goto empty;
 117
 118         l = queue->free.next;
 119         list_del(l);
 120
 121         q = list_entry(l, QE_t, list);
 122         if (BAD_MAGIC(q, QUEUE_MAGIC_FREE))
 123                 BUG();
 124
 125         SET_MAGIC(q, QUEUE_MAGIC_USED);
 126         q->SCpnt = SCpnt;
 127
 128         if (head)
 129                 list_add(l, &queue->head);
 130         else
 131                 list_add_tail(l, &queue->head);
 132
 133         ret = 1;
 134 empty:
 135         spin_unlock_irqrestore(&queue->queue_lock, flags);
 136         return ret;
 137 }
 138
 139 static Scsi_Cmnd *__queue_remove(Queue_t *queue, struct list_head *ent)
 140 {
 141         QE_t *q;
 142
 143         /*
 144          * Move the entry from the "used" list onto the "free" list
 145          */
 146         list_del(ent);
 147         q = list_entry(ent, QE_t, list);
 148         if (BAD_MAGIC(q, QUEUE_MAGIC_USED))
 149                 BUG();
 150
 151         SET_MAGIC(q, QUEUE_MAGIC_FREE);
 152         list_add(ent, &queue->free);
 153
 154         return q->SCpnt;
 155 }
 156
 157 /*
 158  * Function: Scsi_Cmnd *queue_remove_exclude (queue, exclude)
 159  * Purpose : remove a SCSI command from a queue
 160  * Params  : queue   - queue to remove command from
 161  *           exclude - bit array of target&lun which is busy
 162  * Returns : Scsi_Cmnd if successful (and a reference), or NULL if no command available
 163  */
 164 Scsi_Cmnd *queue_remove_exclude(Queue_t *queue, unsigned long *exclude)
 165 {
 166         unsigned long flags;
 167         struct list_head *l;
 168         Scsi_Cmnd *SCpnt = NULL;
 169
 170         spin_lock_irqsave(&queue->queue_lock, flags);
 171         list_for_each(l, &queue->head) {
 172                 QE_t *q = list_entry(l, QE_t, list);
 173                 if (!test_bit(q->SCpnt->target * 8 + q->SCpnt->lun, exclude)) {
 174                         SCpnt = __queue_remove(queue, l);
 175                         break;
 176                 }
 177         }
 178         spin_unlock_irqrestore(&queue->queue_lock, flags);
 179
 180         return SCpnt;
 181 }
 182
 183 /*
 184  * Function: Scsi_Cmnd *queue_remove (queue)
 185  * Purpose : removes first SCSI command from a queue
 186  * Params  : queue   - queue to remove command from
 187  * Returns : Scsi_Cmnd if successful (and a reference), or NULL if no command available
 188  */
 189 Scsi_Cmnd *queue_remove(Queue_t *queue)
 190 {
 191         unsigned long flags;
 192         Scsi_Cmnd *SCpnt = NULL;
 193
 194         spin_lock_irqsave(&queue->queue_lock, flags);
 195         if (!list_empty(&queue->head))
 196                 SCpnt = __queue_remove(queue, queue->head.next);
 197         spin_unlock_irqrestore(&queue->queue_lock, flags);
 198
 199         return SCpnt;
 200 }
 201
 202 /*
 203  * Function: Scsi_Cmnd *queue_remove_tgtluntag (queue, target, lun, tag)
 204  * Purpose : remove a SCSI command from the queue for a specified target/lun/tag
 205  * Params  : queue  - queue to remove command from
 206  *           target - target that we want
 207  *           lun    - lun on device
 208  *           tag    - tag on device
 209  * Returns : Scsi_Cmnd if successful, or NULL if no command satisfies requirements
 210  */
 211 Scsi_Cmnd *queue_remove_tgtluntag (Queue_t *queue, int target, int lun, int tag)
 212 {
 213         unsigned long flags;
 214         struct list_head *l;
 215         Scsi_Cmnd *SCpnt = NULL;
 216
 217         spin_lock_irqsave(&queue->queue_lock, flags);
 218         list_for_each(l, &queue->head) {
 219                 QE_t *q = list_entry(l, QE_t, list);
 220                 if (q->SCpnt->target == target && q->SCpnt->lun == lun &&
 221                     q->SCpnt->tag == tag) {
 222                         SCpnt = __queue_remove(queue, l);
 223                         break;
 224                 }
 225         }
 226         spin_unlock_irqrestore(&queue->queue_lock, flags);
 227
 228         return SCpnt;
 229 }
 230
 231 /*
 232  * Function: queue_remove_all_target(queue, target)
 233  * Purpose : remove all SCSI commands from the queue for a specified target
 234  * Params  : queue  - queue to remove command from
 235  *           target - target device id
 236  * Returns : nothing
 237  */
 238 void queue_remove_all_target(Queue_t *queue, int target)
 239 {
 240         unsigned long flags;
 241         struct list_head *l;
 242
 243         spin_lock_irqsave(&queue->queue_lock, flags);
 244         list_for_each(l, &queue->head) {
 245                 QE_t *q = list_entry(l, QE_t, list);
 246                 if (q->SCpnt->target == target)
 247                         __queue_remove(queue, l);
 248         }
 249         spin_unlock_irqrestore(&queue->queue_lock, flags);
 250 }
 251
 252 /*
 253  * Function: int queue_probetgtlun (queue, target, lun)
 254  * Purpose : check to see if we have a command in the queue for the specified
 255  *           target/lun.
 256  * Params  : queue  - queue to look in
 257  *           target - target we want to probe
 258  *           lun    - lun on target
 259  * Returns : 0 if not found, != 0 if found
 260  */
 261 int queue_probetgtlun (Queue_t *queue, int target, int lun)
 262 {
 263         unsigned long flags;
 264         struct list_head *l;
 265         int found = 0;
 266
 267         spin_lock_irqsave(&queue->queue_lock, flags);
 268         list_for_each(l, &queue->head) {
 269                 QE_t *q = list_entry(l, QE_t, list);
 270                 if (q->SCpnt->target == target && q->SCpnt->lun == lun) {
 271                         found = 1;
 272                         break;
 273                 }
 274         }
 275         spin_unlock_irqrestore(&queue->queue_lock, flags);
 276
 277         return found;
 278 }
 279
 280 /*
 281  * Function: int queue_remove_cmd(Queue_t *queue, Scsi_Cmnd *SCpnt)
 282  * Purpose : remove a specific command from the queues
 283  * Params  : queue - queue to look in
 284  *           SCpnt - command to find
 285  * Returns : 0 if not found
 286  */
 287 int queue_remove_cmd(Queue_t *queue, Scsi_Cmnd *SCpnt)
 288 {
 289         unsigned long flags;
 290         struct list_head *l;
 291         int found = 0;
 292
 293         spin_lock_irqsave(&queue->queue_lock, flags);
 294         list_for_each(l, &queue->head) {
 295                 QE_t *q = list_entry(l, QE_t, list);
 296                 if (q->SCpnt == SCpnt) {
 297                         __queue_remove(queue, l);
 298                         found = 1;
 299                         break;
 300                 }
 301         }
 302         spin_unlock_irqrestore(&queue->queue_lock, flags);
 303
 304         return found;
 305 }
 306
 307 EXPORT_SYMBOL(queue_initialise);
 308 EXPORT_SYMBOL(queue_free);
 309 EXPORT_SYMBOL(__queue_add);
 310 EXPORT_SYMBOL(queue_remove);
 311 EXPORT_SYMBOL(queue_remove_exclude);
 312 EXPORT_SYMBOL(queue_remove_tgtluntag);
 313 EXPORT_SYMBOL(queue_remove_cmd);
 314 EXPORT_SYMBOL(queue_remove_all_target);
 315 EXPORT_SYMBOL(queue_probetgtlun);
 316
 317 MODULE_AUTHOR("Russell King");
 318 MODULE_DESCRIPTION("SCSI command queueing");
 319 MODULE_LICENSE("GPL");