greybus: update svc_msg_header fields and users to match spec

The Greybus spec has been updated to clarify some of the original
intent of the SVC message definition. The svc_msg_header was:

struct svc_msg_header {
	__u8 function;
	__u8 message_type;
...
}

and is now

struct svc_msg_header {
	__u8 function_id;
	__u8 message_type;
...
}

to match the spec. The function_id carries enum svc_function_id values
and message_type is now clarified to be a session layer level field
that is simply "data" or "error".

Change all references of function type to function id. For now, don't
parse the message_type field but add the two allowable svc_msg_type enums.
Signed-off-by: Matt Porter <mporter@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/staging/greybus/ap.c

@@ -29,7 +29,7 @@ struct ap_msg {
 
 static struct workqueue_struct *ap_workqueue;
 
-static struct svc_msg *svc_msg_alloc(enum svc_function_type type)
+static struct svc_msg *svc_msg_alloc(enum svc_function_id id)
 {
 	struct svc_msg *svc_msg;
 
@@ -37,8 +37,8 @@ static struct svc_msg *svc_msg_alloc(enum svc_function_type type)
 	if (!svc_msg)
 		return NULL;
 
-	// FIXME - verify we are only sending message types we should be
-	svc_msg->header.type = type;
+	// FIXME - verify we are only sending function IDs we should be
+	svc_msg->header.function_id = id;
 	return svc_msg;
 }
 
@@ -187,7 +187,7 @@ static void ap_process_event(struct work_struct *work)
 	}
 
 	/* Look at the message to figure out what to do with it */
-	switch (svc_msg->header.type) {
+	switch (svc_msg->header.function_id) {
 	case SVC_FUNCTION_HANDSHAKE:
 		svc_handshake(&svc_msg->handshake, hd);
 		break;
@@ -210,8 +210,8 @@ static void ap_process_event(struct work_struct *work)
 		svc_suspend(&svc_msg->suspend, hd);
 		break;
 	default:
-		dev_err(hd->parent, "received invalid SVC message type %d\n",
-			svc_msg->header.type);
+		dev_err(hd->parent, "received invalid SVC function ID %d\n",
+			svc_msg->header.function_id);
 	}
 
 	/* clean the message up */

drivers/staging/greybus/svc_msg.h

@@ -12,7 +12,7 @@
 
 #pragma pack(push, 1)
 
-enum svc_function_type {
+enum svc_function_id {
 	SVC_FUNCTION_HANDSHAKE			= 0x00,
 	SVC_FUNCTION_UNIPRO_NETWORK_MANAGEMENT	= 0x01,
 	SVC_FUNCTION_HOTPLUG			= 0x02,
@@ -22,9 +22,14 @@ enum svc_function_type {
 	SVC_FUNCTION_SUSPEND			= 0x06,
 };
 
+enum svc_msg_type {
+	SVC_MSG_DATA				= 0x00,
+	SVC_MSG_ERROR				= 0xff,
+};
+
 struct svc_msg_header {
-	__u8	function;
-	__u8	type;		/* enum svc_function_type */
+	__u8	function_id;	/* enum svc_function_id */
+	__u8	message_type;
 	__u8	version_major;
 	__u8	version_minor;
 	__le16	payload_length;