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/blkdev.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.h"
27
28#define DEBUG
29
30typedef struct queue_entry {
31	struct list_head   list;
32	struct 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 */
58int 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 */
90void queue_free (Queue_t *queue)
91{
92	if (!list_empty(&queue->head))
93		printk(KERN_WARNING "freeing non-empty queue %p\n", queue);
94	kfree(queue->alloc);
95}
96
97
98/*
99 * Function: int __queue_add(Queue_t *queue, struct scsi_cmnd *SCpnt, int head)
100 * Purpose : Add a new command onto a queue, adding REQUEST_SENSE to head.
101 * Params  : queue - destination queue
102 *	     SCpnt - command to add
103 *	     head  - add command to head of queue
104 * Returns : 0 on error, !0 on success
105 */
106int __queue_add(Queue_t *queue, struct scsi_cmnd *SCpnt, int head)
107{
108	unsigned long flags;
109	struct list_head *l;
110	QE_t *q;
111	int ret = 0;
112
113	spin_lock_irqsave(&queue->queue_lock, flags);
114	if (list_empty(&queue->free))
115		goto empty;
116
117	l = queue->free.next;
118	list_del(l);
119
120	q = list_entry(l, QE_t, list);
121	BUG_ON(BAD_MAGIC(q, QUEUE_MAGIC_FREE));
122
123	SET_MAGIC(q, QUEUE_MAGIC_USED);
124	q->SCpnt = SCpnt;
125
126	if (head)
127		list_add(l, &queue->head);
128	else
129		list_add_tail(l, &queue->head);
130
131	ret = 1;
132empty:
133	spin_unlock_irqrestore(&queue->queue_lock, flags);
134	return ret;
135}
136
137static struct scsi_cmnd *__queue_remove(Queue_t *queue, struct list_head *ent)
138{
139	QE_t *q;
140
141	/*
142	 * Move the entry from the "used" list onto the "free" list
143	 */
144	list_del(ent);
145	q = list_entry(ent, QE_t, list);
146	BUG_ON(BAD_MAGIC(q, QUEUE_MAGIC_USED));
147
148	SET_MAGIC(q, QUEUE_MAGIC_FREE);
149	list_add(ent, &queue->free);
150
151	return q->SCpnt;
152}
153
154/*
155 * Function: struct scsi_cmnd *queue_remove_exclude (queue, exclude)
156 * Purpose : remove a SCSI command from a queue
157 * Params  : queue   - queue to remove command from
158 *	     exclude - bit array of target&lun which is busy
159 * Returns : struct scsi_cmnd if successful (and a reference), or NULL if no command available
160 */
161struct scsi_cmnd *queue_remove_exclude(Queue_t *queue, unsigned long *exclude)
162{
163	unsigned long flags;
164	struct list_head *l;
165	struct scsi_cmnd *SCpnt = NULL;
166
167	spin_lock_irqsave(&queue->queue_lock, flags);
168	list_for_each(l, &queue->head) {
169		QE_t *q = list_entry(l, QE_t, list);
170		if (!test_bit(q->SCpnt->device->id * 8 +
171			      (u8)(q->SCpnt->device->lun & 0x7), exclude)) {
172			SCpnt = __queue_remove(queue, l);
173			break;
174		}
175	}
176	spin_unlock_irqrestore(&queue->queue_lock, flags);
177
178	return SCpnt;
179}
180
181/*
182 * Function: struct scsi_cmnd *queue_remove (queue)
183 * Purpose : removes first SCSI command from a queue
184 * Params  : queue   - queue to remove command from
185 * Returns : struct scsi_cmnd if successful (and a reference), or NULL if no command available
186 */
187struct scsi_cmnd *queue_remove(Queue_t *queue)
188{
189	unsigned long flags;
190	struct scsi_cmnd *SCpnt = NULL;
191
192	spin_lock_irqsave(&queue->queue_lock, flags);
193	if (!list_empty(&queue->head))
194		SCpnt = __queue_remove(queue, queue->head.next);
195	spin_unlock_irqrestore(&queue->queue_lock, flags);
196
197	return SCpnt;
198}
199
200/*
201 * Function: struct scsi_cmnd *queue_remove_tgtluntag (queue, target, lun, tag)
202 * Purpose : remove a SCSI command from the queue for a specified target/lun/tag
203 * Params  : queue  - queue to remove command from
204 *	     target - target that we want
205 *	     lun    - lun on device
206 *	     tag    - tag on device
207 * Returns : struct scsi_cmnd if successful, or NULL if no command satisfies requirements
208 */
209struct scsi_cmnd *queue_remove_tgtluntag(Queue_t *queue, int target, int lun,
210					 int tag)
211{
212	unsigned long flags;
213	struct list_head *l;
214	struct scsi_cmnd *SCpnt = NULL;
215
216	spin_lock_irqsave(&queue->queue_lock, flags);
217	list_for_each(l, &queue->head) {
218		QE_t *q = list_entry(l, QE_t, list);
219		if (q->SCpnt->device->id == target && q->SCpnt->device->lun == lun &&
220		    q->SCpnt->tag == tag) {
221			SCpnt = __queue_remove(queue, l);
222			break;
223		}
224	}
225	spin_unlock_irqrestore(&queue->queue_lock, flags);
226
227	return SCpnt;
228}
229
230/*
231 * Function: queue_remove_all_target(queue, target)
232 * Purpose : remove all SCSI commands from the queue for a specified target
233 * Params  : queue  - queue to remove command from
234 *           target - target device id
235 * Returns : nothing
236 */
237void queue_remove_all_target(Queue_t *queue, int target)
238{
239	unsigned long flags;
240	struct list_head *l;
241
242	spin_lock_irqsave(&queue->queue_lock, flags);
243	list_for_each(l, &queue->head) {
244		QE_t *q = list_entry(l, QE_t, list);
245		if (q->SCpnt->device->id == target)
246			__queue_remove(queue, l);
247	}
248	spin_unlock_irqrestore(&queue->queue_lock, flags);
249}
250
251/*
252 * Function: int queue_probetgtlun (queue, target, lun)
253 * Purpose : check to see if we have a command in the queue for the specified
254 *	     target/lun.
255 * Params  : queue  - queue to look in
256 *	     target - target we want to probe
257 *	     lun    - lun on target
258 * Returns : 0 if not found, != 0 if found
259 */
260int queue_probetgtlun (Queue_t *queue, int target, int lun)
261{
262	unsigned long flags;
263	struct list_head *l;
264	int found = 0;
265
266	spin_lock_irqsave(&queue->queue_lock, flags);
267	list_for_each(l, &queue->head) {
268		QE_t *q = list_entry(l, QE_t, list);
269		if (q->SCpnt->device->id == target && q->SCpnt->device->lun == lun) {
270			found = 1;
271			break;
272		}
273	}
274	spin_unlock_irqrestore(&queue->queue_lock, flags);
275
276	return found;
277}
278
279/*
280 * Function: int queue_remove_cmd(Queue_t *queue, struct scsi_cmnd *SCpnt)
281 * Purpose : remove a specific command from the queues
282 * Params  : queue - queue to look in
283 *	     SCpnt - command to find
284 * Returns : 0 if not found
285 */
286int queue_remove_cmd(Queue_t *queue, struct scsi_cmnd *SCpnt)
287{
288	unsigned long flags;
289	struct list_head *l;
290	int found = 0;
291
292	spin_lock_irqsave(&queue->queue_lock, flags);
293	list_for_each(l, &queue->head) {
294		QE_t *q = list_entry(l, QE_t, list);
295		if (q->SCpnt == SCpnt) {
296			__queue_remove(queue, l);
297			found = 1;
298			break;
299		}
300	}
301	spin_unlock_irqrestore(&queue->queue_lock, flags);
302
303	return found;
304}
305
306EXPORT_SYMBOL(queue_initialise);
307EXPORT_SYMBOL(queue_free);
308EXPORT_SYMBOL(__queue_add);
309EXPORT_SYMBOL(queue_remove);
310EXPORT_SYMBOL(queue_remove_exclude);
311EXPORT_SYMBOL(queue_remove_tgtluntag);
312EXPORT_SYMBOL(queue_remove_cmd);
313EXPORT_SYMBOL(queue_remove_all_target);
314EXPORT_SYMBOL(queue_probetgtlun);
315
316MODULE_AUTHOR("Russell King");
317MODULE_DESCRIPTION("SCSI command queueing");
318MODULE_LICENSE("GPL");
319