m68k/mac/iop.c

30  * 990610 (jmt) - Finished the message passing framework and it seems to work.
33  *		  IOP. The trick now is figuring out the message formats.
65  * The host talks to the IOPs using a rather simple message-passing scheme via
69  * an incoming and an outgoing message queue with a depth of one.
71  * A message is 32 bytes plus a state byte for the channel (MSG_IDLE, MSG_NEW,
72  * MSG_RCVD, MSG_COMPLETE). To send a message you copy the message into the
75  * receives the message and then to MSG_COMPLETE when the message processing
80  * To receive message from the IOP the same procedure is used except the roles
81  * are reversed. That is, the IOP puts message in the channel with a state of
82  * MSG_NEW, and the host receives the message and move its state to MSG_RCVD
93  * Since each channel handles only one message we have to implement a small
96  * The handler for a message is called when the message state goes to
99  * For receiving message we maintain a list of handler functions to call when
100  * a message is received on that IOP/channel combination. The handlers are
101  * called much like an interrupt handler and are passed a copy of the message
102  * from the IOP. The message state will be in MSG_RCVD while the handler runs;
104  * finished; this function moves the message state to MSG_COMPLETE and signals
106  * message processing to a bottom-half handler if the processing will take
157  * IOP message queues
323  * Complete reception of a message, which just means copying the reply
351  * Actually put a message into a send channel buffer
359 	iop_pr_debug("iop_num %d chan %d message %*ph\n",
360 		     msg->iop_num, msg->channel, IOP_MSG_LEN, msg->message);
365 		iop_writeb(iop, offset, msg->message[i]);
374  * Handle sending a message on a channel that
405  * Handle reception of a message on a channel that has
424 		msg->message[i] = iop_readb(iop, offset);
426 	iop_pr_debug("iop_num %d chan %d message %*ph\n",
427 		     iop_num, chan, IOP_MSG_LEN, msg->message);
432 	/* the message ourselves to avoid possible stalls.         */
443  * Send a message
445  * The message is placed at the end of the send queue. Afterwards if the
446  * channel is idle we force an immediate send of the next message in the
468 	memcpy(msg->message, msg_data, msg_len);
551 		/* INT0 indicates state change on an outgoing message channel */