drivers/scsi/arm/msgqueue.c

   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  */
  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  */
  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  */
  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  */
  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  */
  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  */
  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  */
 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  */
 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");