--- a/target-utils/simagent/spenh.c	Sat Mar 13 22:17:39 2021 +0000
+++ b/target-utils/simagent/spenh.c	Sat Mar 13 22:41:33 2021 +0000
@@ -3,8 +3,43 @@
 #include "types.h"
 #include "simregs.h"
 
+extern int sim_if_state;
 extern u16 conf1_reg;
 
+const u8 pts_for_spenh[4] = {0xFF, 0x10, 0x94, 0x7B};
+
+void
+cmd_spenh()
+{
+	int rc;
+	unsigned count;
+
+	if (sim_if_state != 2) {
+		printf("ERROR: SIM interface is not up\n");
+		return;
+	}
+	if (conf1_reg & SIM_CONF1_ETU) {
+		printf("ERROR: speed enhancement is already on\n");
+		return;
+	}
+	rc = flush_rx_fifo();
+	if (rc < 0)
+		return;
+	rc = send_to_sim(pts_for_spenh, 4);
+	if (rc < 0)
+		return;
+	for (count = 0; count < 4; count++) {
+		rc = rx_sim_byte_hl();
+		if (rc < 0)
+			return;
+		if (rc != pts_for_spenh[count]) {
+			printf("ERROR: PTS response does not match request\n");
+			return;
+		}
+	}
+	SIMREGS.conf1 = conf1_reg |= SIM_CONF1_ETU;
+}
+
 void
 cmd_set_spenh(argbulk)
 	char *argbulk;