greybus: loopback: define loopback functions symbolically

Add some symbols to indicate what kind of "function" the
loopback thread is supposed to be performing--the type of
traffic it generates over its connection.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/loopback.c

@@ -55,6 +55,12 @@ struct gb_loopback {
 #define	GB_LOOPBACK_TYPE_PING				0x02
 #define	GB_LOOPBACK_TYPE_TRANSFER			0x03
 
+/* Current function (type of traffic generated by the loopback thread) */
+#define GB_LOOPBACK_FN_NONE				0x00
+#define GB_LOOPBACK_FN_PING				0x01
+#define GB_LOOPBACK_FN_XFER				0x02
+#define GB_LOOPBACK_FN_COUNT				0x03
+
 #define GB_LOOPBACK_MS_WAIT_MAX				1000
 #define GB_LOOPBACK_SIZE_MAX				SZ_4K
 
@@ -124,8 +130,8 @@ static void gb_loopback_check_attr(struct gb_loopback *gb)
 {
 	if (gb->ms_wait > GB_LOOPBACK_MS_WAIT_MAX)
 		gb->ms_wait = GB_LOOPBACK_MS_WAIT_MAX;
-	if (gb->type > 2)
-		gb->type = 0;
+	if (gb->type >= GB_LOOPBACK_FN_COUNT)
+		gb->type = GB_LOOPBACK_FN_NONE;
 	if (gb->size > GB_LOOPBACK_SIZE_MAX)
 		gb->size = GB_LOOPBACK_SIZE_MAX;
 	gb->error = 0;
@@ -310,13 +316,13 @@ static int gb_loopback_fn(void *data)
 	struct gb_loopback *gb = (struct gb_loopback *)data;
 
 	while (!kthread_should_stop()) {
-		if (gb->type == 0) {
+		if (gb->type == GB_LOOPBACK_FN_NONE) {
 			msleep(1000);
 			continue;
 		}
-		if (gb->type == 1)
+		if (gb->type == GB_LOOPBACK_FN_PING)
 			error = gb_loopback_ping(gb, &tlat);
-		if (gb->type == 2)
+		else if (gb->type == GB_LOOPBACK_FN_XFER)
 			error = gb_loopback_transfer(gb, &tlat, gb->size);
 		if (error)
 			gb->error++;