diff --git a/contrib/itmdump.c b/contrib/itmdump.c
index 71f6e0670..896389416 100644
--- a/contrib/itmdump.c
+++ b/contrib/itmdump.c
@@ -44,6 +44,7 @@
 #include <string.h>
 #include <unistd.h>
 
+unsigned int dump_swit;
 
 /* Example ITM trace word (0xWWXXYYZZ) parsing for task events, sent
  * on port 31 (Reserved for "the" RTOS in CMSIS v1.30)
@@ -59,6 +60,9 @@ static void show_task(int port, unsigned data)
 	unsigned code = data >> 16;
 	char buf[16];
 
+	if (dump_swit)
+		return;
+
 	switch (code) {
 	case 0:
 		strcpy(buf, "run");
@@ -87,6 +91,9 @@ static void show_reserved(FILE *f, char *label, int c)
 {
 	unsigned i;
 
+	if (dump_swit)
+		return;
+
 	printf("%s - %#02x", label, c);
 
 	for (i = 0; (c & 0x80) && i < 4; i++) {
@@ -144,6 +151,9 @@ static void show_hard(FILE *f, int c)
 	unsigned value;
 	char *label;
 
+	if (dump_swit)
+		return;
+
 	printf("DWT - ");
 
 	if (!read_varlen(f, c, &value))
@@ -243,10 +253,21 @@ static void show_swit(FILE *f, int c)
 	unsigned value = 0;
 	unsigned i;
 
-	printf("SWIT %u - ", port);
+	if (port + 1 == dump_swit) {
+		if (!read_varlen(f, c, &value))
+			return;
+		printf("%c", value);
+		return;
+	}
 
 	if (!read_varlen(f, c, &value))
 		return;
+
+	if (dump_swit)
+		return;
+
+	printf("SWIT %u - ", port);
+
 	printf("%#08x", value);
 
 	for (i = 0; i < sizeof(format) / sizeof(format[0]); i++) {
@@ -267,6 +288,9 @@ static void show_timestamp(FILE *f, int c)
 	char *label = "";
 	bool delayed = false;
 
+	if (dump_swit)
+		return;
+
 	printf("TIMESTAMP - ");
 
 	/* Format 2: header only */
@@ -285,7 +309,7 @@ static void show_timestamp(FILE *f, int c)
 	}
 
 	/* Format 1:  one to four bytes of data too */
-	switch (c) {
+	switch (c >> 4) {
 	default:
 		label = ", reserved control\n";
 		break;
@@ -348,7 +372,7 @@ int main(int argc, char **argv)
 	int c;
 
 	/* parse arguments */
-	while ((c = getopt(argc, argv, "f:")) != EOF) {
+	while ((c = getopt(argc, argv, "f:d:")) != EOF) {
 		switch (c) {
 		case 'f':
 			/* e.g. from UART connected to /dev/ttyUSB0 */
@@ -358,6 +382,9 @@ int main(int argc, char **argv)
 				return 1;
 			}
 			break;
+		case 'd':
+			dump_swit = atoi(optarg);
+			break;
 		default:
 			fprintf(stderr, "usage: %s [-f input]",
 				basename(argv[0]));