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 + q->SCpnt->device->lun, exclude)) {
171			SCpnt = __queue_remove(queue, l);
172			break;
173		}
174	}
175	spin_unlock_irqrestore(&queue->queue_lock, flags);
176
177	return SCpnt;
178}
179
180/*
181 * Function: struct scsi_cmnd *queue_remove (queue)
182 * Purpose : removes first SCSI command from a queue
183 * Params  : queue   - queue to remove command from
184 * Returns : struct scsi_cmnd if successful (and a reference), or NULL if no command available
185 */
186struct scsi_cmnd *queue_remove(Queue_t *queue)
187{
188	unsigned long flags;
189	struct scsi_cmnd *SCpnt = NULL;
190
191	spin_lock_irqsave(&queue->queue_lock, flags);
192	if (!list_empty(&queue->head))
193		SCpnt = __queue_remove(queue, queue->head.next);
194	spin_unlock_irqrestore(&queue->queue_lock, flags);
195
196	return SCpnt;
197}
198
199/*
200 * Function: struct scsi_cmnd *queue_remove_tgtluntag (queue, target, lun, tag)
201 * Purpose : remove a SCSI command from the queue for a specified target/lun/tag
202 * Params  : queue  - queue to remove command from
203 *	     target - target that we want
204 *	     lun    - lun on device
205 *	     tag    - tag on device
206 * Returns : struct scsi_cmnd if successful, or NULL if no command satisfies requirements
207 */
208struct scsi_cmnd *queue_remove_tgtluntag(Queue_t *queue, int target, int lun,
209					 int tag)
210{
211	unsigned long flags;
212	struct list_head *l;
213	struct scsi_cmnd *SCpnt = NULL;
214
215	spin_lock_irqsave(&queue->queue_lock, flags);
216	list_for_each(l, &queue->head) {
217		QE_t *q = list_entry(l, QE_t, list);
218		if (q->SCpnt->device->id == target && q->SCpnt->device->lun == lun &&
219		    q->SCpnt->tag == tag) {
220			SCpnt = __queue_remove(queue, l);
221			break;
222		}
223	}
224	spin_unlock_irqrestore(&queue->queue_lock, flags);
225
226	return SCpnt;
227}
228
229/*
230 * Function: queue_remove_all_target(queue, target)
231 * Purpose : remove all SCSI commands from the queue for a specified target
232 * Params  : queue  - queue to remove command from
233 *           target - target device id
234 * Returns : nothing
235 */
236void queue_remove_all_target(Queue_t *queue, int target)
237{
238	unsigned long flags;
239	struct list_head *l;
240
241	spin_lock_irqsave(&queue->queue_lock, flags);
242	list_for_each(l, &queue->head) {
243		QE_t *q = list_entry(l, QE_t, list);
244		if (q->SCpnt->device->id == target)
245			__queue_remove(queue, l);
246	}
247	spin_unlock_irqrestore(&queue->queue_lock, flags);
248}
249
250/*
251 * Function: int queue_probetgtlun (queue, target, lun)
252 * Purpose : check to see if we have a command in the queue for the specified
253 *	     target/lun.
254 * Params  : queue  - queue to look in
255 *	     target - target we want to probe
256 *	     lun    - lun on target
257 * Returns : 0 if not found, != 0 if found
258 */
259int queue_probetgtlun (Queue_t *queue, int target, int lun)
260{
261	unsigned long flags;
262	struct list_head *l;
263	int found = 0;
264
265	spin_lock_irqsave(&queue->queue_lock, flags);
266	list_for_each(l, &queue->head) {
267		QE_t *q = list_entry(l, QE_t, list);
268		if (q->SCpnt->device->id == target && q->SCpnt->device->lun == lun) {
269			found = 1;
270			break;
271		}
272	}
273	spin_unlock_irqrestore(&queue->queue_lock, flags);
274
275	return found;
276}
277
278/*
279 * Function: int queue_remove_cmd(Queue_t *queue, struct scsi_cmnd *SCpnt)
280 * Purpose : remove a specific command from the queues
281 * Params  : queue - queue to look in
282 *	     SCpnt - command to find
283 * Returns : 0 if not found
284 */
285int queue_remove_cmd(Queue_t *queue, struct scsi_cmnd *SCpnt)
286{
287	unsigned long flags;
288	struct list_head *l;
289	int found = 0;
290
291	spin_lock_irqsave(&queue->queue_lock, flags);
292	list_for_each(l, &queue->head) {
293		QE_t *q = list_entry(l, QE_t, list);
294		if (q->SCpnt == SCpnt) {
295			__queue_remove(queue, l);
296			found = 1;
297			break;
298		}
299	}
300	spin_unlock_irqrestore(&queue->queue_lock, flags);
301
302	return found;
303}
304
305EXPORT_SYMBOL(queue_initialise);
306EXPORT_SYMBOL(queue_free);
307EXPORT_SYMBOL(__queue_add);
308EXPORT_SYMBOL(queue_remove);
309EXPORT_SYMBOL(queue_remove_exclude);
310EXPORT_SYMBOL(queue_remove_tgtluntag);
311EXPORT_SYMBOL(queue_remove_cmd);
312EXPORT_SYMBOL(queue_remove_all_target);
313EXPORT_SYMBOL(queue_probetgtlun);
314
315MODULE_AUTHOR("Russell King");
316MODULE_DESCRIPTION("SCSI command queueing");
317MODULE_LICENSE("GPL");
318