1 /*
2  *  linux/drivers/acorn/scsi/msgqueue.c
3  *
4  *  Copyright (C) 1997-1998 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  *  message queue handling
11  */
12 #include <linux/module.h>
13 #include <linux/kernel.h>
14 #include <linux/stddef.h>
15 #include <linux/init.h>
16 
17 #include "msgqueue.h"
18 
19 /*
20  * Function: struct msgqueue_entry *mqe_alloc(MsgQueue_t *msgq)
21  * Purpose : Allocate a message queue entry
22  * Params  : msgq - message queue to claim entry for
23  * Returns : message queue entry or NULL.
24  */
mqe_alloc(MsgQueue_t * msgq)25 static struct msgqueue_entry *mqe_alloc(MsgQueue_t *msgq)
26 {
27 	struct msgqueue_entry *mq;
28 
29 	if ((mq = msgq->free) != NULL)
30 		msgq->free = mq->next;
31 
32 	return mq;
33 }
34 
35 /*
36  * Function: void mqe_free(MsgQueue_t *msgq, struct msgqueue_entry *mq)
37  * Purpose : free a message queue entry
38  * Params  : msgq - message queue to free entry from
39  *	     mq   - message queue entry to free
40  */
mqe_free(MsgQueue_t * msgq,struct msgqueue_entry * mq)41 static void mqe_free(MsgQueue_t *msgq, struct msgqueue_entry *mq)
42 {
43 	if (mq) {
44 		mq->next = msgq->free;
45 		msgq->free = mq;
46 	}
47 }
48 
49 /*
50  * Function: void msgqueue_initialise(MsgQueue_t *msgq)
51  * Purpose : initialise a message queue
52  * Params  : msgq - queue to initialise
53  */
msgqueue_initialise(MsgQueue_t * msgq)54 void msgqueue_initialise(MsgQueue_t *msgq)
55 {
56 	int i;
57 
58 	msgq->qe = NULL;
59 	msgq->free = &msgq->entries[0];
60 
61 	for (i = 0; i < NR_MESSAGES; i++)
62 		msgq->entries[i].next = &msgq->entries[i + 1];
63 
64 	msgq->entries[NR_MESSAGES - 1].next = NULL;
65 }
66 
67 
68 /*
69  * Function: void msgqueue_free(MsgQueue_t *msgq)
70  * Purpose : free a queue
71  * Params  : msgq - queue to free
72  */
msgqueue_free(MsgQueue_t * msgq)73 void msgqueue_free(MsgQueue_t *msgq)
74 {
75 }
76 
77 /*
78  * Function: int msgqueue_msglength(MsgQueue_t *msgq)
79  * Purpose : calculate the total length of all messages on the message queue
80  * Params  : msgq - queue to examine
81  * Returns : number of bytes of messages in queue
82  */
msgqueue_msglength(MsgQueue_t * msgq)83 int msgqueue_msglength(MsgQueue_t *msgq)
84 {
85 	struct msgqueue_entry *mq = msgq->qe;
86 	int length = 0;
87 
88 	for (mq = msgq->qe; mq; mq = mq->next)
89 		length += mq->msg.length;
90 
91 	return length;
92 }
93 
94 /*
95  * Function: struct message *msgqueue_getmsg(MsgQueue_t *msgq, int msgno)
96  * Purpose : return a message
97  * Params  : msgq   - queue to obtain message from
98  *	   : msgno  - message number
99  * Returns : pointer to message string, or NULL
100  */
msgqueue_getmsg(MsgQueue_t * msgq,int msgno)101 struct message *msgqueue_getmsg(MsgQueue_t *msgq, int msgno)
102 {
103 	struct msgqueue_entry *mq;
104 
105 	for (mq = msgq->qe; mq && msgno; mq = mq->next, msgno--);
106 
107 	return mq ? &mq->msg : NULL;
108 }
109 
110 /*
111  * Function: int msgqueue_addmsg(MsgQueue_t *msgq, int length, ...)
112  * Purpose : add a message onto a message queue
113  * Params  : msgq   - queue to add message on
114  *	     length - length of message
115  *	     ...    - message bytes
116  * Returns : != 0 if successful
117  */
msgqueue_addmsg(MsgQueue_t * msgq,int length,...)118 int msgqueue_addmsg(MsgQueue_t *msgq, int length, ...)
119 {
120 	struct msgqueue_entry *mq = mqe_alloc(msgq);
121 	va_list ap;
122 
123 	if (mq) {
124 		struct msgqueue_entry **mqp;
125 		int i;
126 
127 		va_start(ap, length);
128 		for (i = 0; i < length; i++)
129 			mq->msg.msg[i] = va_arg(ap, unsigned int);
130 		va_end(ap);
131 
132 		mq->msg.length = length;
133 		mq->msg.fifo = 0;
134 		mq->next = NULL;
135 
136 		mqp = &msgq->qe;
137 		while (*mqp)
138 			mqp = &(*mqp)->next;
139 
140 		*mqp = mq;
141 	}
142 
143 	return mq != NULL;
144 }
145 
146 /*
147  * Function: void msgqueue_flush(MsgQueue_t *msgq)
148  * Purpose : flush all messages from message queue
149  * Params  : msgq - queue to flush
150  */
msgqueue_flush(MsgQueue_t * msgq)151 void msgqueue_flush(MsgQueue_t *msgq)
152 {
153 	struct msgqueue_entry *mq, *mqnext;
154 
155 	for (mq = msgq->qe; mq; mq = mqnext) {
156 		mqnext = mq->next;
157 		mqe_free(msgq, mq);
158 	}
159 	msgq->qe = NULL;
160 }
161 
162 EXPORT_SYMBOL(msgqueue_initialise);
163 EXPORT_SYMBOL(msgqueue_free);
164 EXPORT_SYMBOL(msgqueue_msglength);
165 EXPORT_SYMBOL(msgqueue_getmsg);
166 EXPORT_SYMBOL(msgqueue_addmsg);
167 EXPORT_SYMBOL(msgqueue_flush);
168 
169 MODULE_AUTHOR("Russell King");
170 MODULE_DESCRIPTION("SCSI message queue handling");
171 MODULE_LICENSE("GPL");
172