1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  linux/drivers/acorn/scsi/msgqueue.c
4  *
5  *  Copyright (C) 1997-1998 Russell King
6  *
7  *  message queue handling
8  */
9 #include <linux/module.h>
10 #include <linux/kernel.h>
11 #include <linux/stddef.h>
12 #include <linux/init.h>
13 
14 #include "msgqueue.h"
15 
16 /*
17  * Function: struct msgqueue_entry *mqe_alloc(MsgQueue_t *msgq)
18  * Purpose : Allocate a message queue entry
19  * Params  : msgq - message queue to claim entry for
20  * Returns : message queue entry or NULL.
21  */
mqe_alloc(MsgQueue_t * msgq)22 static struct msgqueue_entry *mqe_alloc(MsgQueue_t *msgq)
23 {
24 	struct msgqueue_entry *mq;
25 
26 	if ((mq = msgq->free) != NULL)
27 		msgq->free = mq->next;
28 
29 	return mq;
30 }
31 
32 /*
33  * Function: void mqe_free(MsgQueue_t *msgq, struct msgqueue_entry *mq)
34  * Purpose : free a message queue entry
35  * Params  : msgq - message queue to free entry from
36  *	     mq   - message queue entry to free
37  */
mqe_free(MsgQueue_t * msgq,struct msgqueue_entry * mq)38 static void mqe_free(MsgQueue_t *msgq, struct msgqueue_entry *mq)
39 {
40 	if (mq) {
41 		mq->next = msgq->free;
42 		msgq->free = mq;
43 	}
44 }
45 
46 /*
47  * Function: void msgqueue_initialise(MsgQueue_t *msgq)
48  * Purpose : initialise a message queue
49  * Params  : msgq - queue to initialise
50  */
msgqueue_initialise(MsgQueue_t * msgq)51 void msgqueue_initialise(MsgQueue_t *msgq)
52 {
53 	int i;
54 
55 	msgq->qe = NULL;
56 	msgq->free = &msgq->entries[0];
57 
58 	for (i = 0; i < NR_MESSAGES; i++)
59 		msgq->entries[i].next = &msgq->entries[i + 1];
60 
61 	msgq->entries[NR_MESSAGES - 1].next = NULL;
62 }
63 
64 
65 /*
66  * Function: void msgqueue_free(MsgQueue_t *msgq)
67  * Purpose : free a queue
68  * Params  : msgq - queue to free
69  */
msgqueue_free(MsgQueue_t * msgq)70 void msgqueue_free(MsgQueue_t *msgq)
71 {
72 }
73 
74 /*
75  * Function: int msgqueue_msglength(MsgQueue_t *msgq)
76  * Purpose : calculate the total length of all messages on the message queue
77  * Params  : msgq - queue to examine
78  * Returns : number of bytes of messages in queue
79  */
msgqueue_msglength(MsgQueue_t * msgq)80 int msgqueue_msglength(MsgQueue_t *msgq)
81 {
82 	struct msgqueue_entry *mq = msgq->qe;
83 	int length = 0;
84 
85 	for (mq = msgq->qe; mq; mq = mq->next)
86 		length += mq->msg.length;
87 
88 	return length;
89 }
90 
91 /*
92  * Function: struct message *msgqueue_getmsg(MsgQueue_t *msgq, int msgno)
93  * Purpose : return a message
94  * Params  : msgq   - queue to obtain message from
95  *	   : msgno  - message number
96  * Returns : pointer to message string, or NULL
97  */
msgqueue_getmsg(MsgQueue_t * msgq,int msgno)98 struct message *msgqueue_getmsg(MsgQueue_t *msgq, int msgno)
99 {
100 	struct msgqueue_entry *mq;
101 
102 	for (mq = msgq->qe; mq && msgno; mq = mq->next, msgno--);
103 
104 	return mq ? &mq->msg : NULL;
105 }
106 
107 /*
108  * Function: int msgqueue_addmsg(MsgQueue_t *msgq, int length, ...)
109  * Purpose : add a message onto a message queue
110  * Params  : msgq   - queue to add message on
111  *	     length - length of message
112  *	     ...    - message bytes
113  * Returns : != 0 if successful
114  */
msgqueue_addmsg(MsgQueue_t * msgq,int length,...)115 int msgqueue_addmsg(MsgQueue_t *msgq, int length, ...)
116 {
117 	struct msgqueue_entry *mq = mqe_alloc(msgq);
118 	va_list ap;
119 
120 	if (mq) {
121 		struct msgqueue_entry **mqp;
122 		int i;
123 
124 		va_start(ap, length);
125 		for (i = 0; i < length; i++)
126 			mq->msg.msg[i] = va_arg(ap, unsigned int);
127 		va_end(ap);
128 
129 		mq->msg.length = length;
130 		mq->msg.fifo = 0;
131 		mq->next = NULL;
132 
133 		mqp = &msgq->qe;
134 		while (*mqp)
135 			mqp = &(*mqp)->next;
136 
137 		*mqp = mq;
138 	}
139 
140 	return mq != NULL;
141 }
142 
143 /*
144  * Function: void msgqueue_flush(MsgQueue_t *msgq)
145  * Purpose : flush all messages from message queue
146  * Params  : msgq - queue to flush
147  */
msgqueue_flush(MsgQueue_t * msgq)148 void msgqueue_flush(MsgQueue_t *msgq)
149 {
150 	struct msgqueue_entry *mq, *mqnext;
151 
152 	for (mq = msgq->qe; mq; mq = mqnext) {
153 		mqnext = mq->next;
154 		mqe_free(msgq, mq);
155 	}
156 	msgq->qe = NULL;
157 }
158 
159 EXPORT_SYMBOL(msgqueue_initialise);
160 EXPORT_SYMBOL(msgqueue_free);
161 EXPORT_SYMBOL(msgqueue_msglength);
162 EXPORT_SYMBOL(msgqueue_getmsg);
163 EXPORT_SYMBOL(msgqueue_addmsg);
164 EXPORT_SYMBOL(msgqueue_flush);
165 
166 MODULE_AUTHOR("Russell King");
167 MODULE_DESCRIPTION("SCSI message queue handling");
168 MODULE_LICENSE("GPL");
169