--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/target-utils/pln-ppb-test/mode_entry.c	Sat Dec 02 23:50:07 2023 +0000
@@ -0,0 +1,32 @@
+/*
+ * mode-entry and mode-exit commands
+ */
+
+#include <sys/types.h>
+#include "types.h"
+
+void
+cmd_mode_entry(argbulk)
+	char *argbulk;
+{
+	char *argv[3];
+	u_long addr, mode;
+
+	if (parse_args(argbulk, 2, 2, argv, 0) < 0)
+		return;
+	if (parse_hexarg(argv[0], 8, &addr) < 0) {
+		printf("ERROR: arg1 must be a valid 32-bit hex address\n");
+		return;
+	}
+	if (addr & 0xFFFF) {
+		printf("ERROR: address is not on 64 KiB boundary\n");
+		return;
+	}
+	if (parse_hexarg(argv[1], 4, &mode) < 0) {
+		printf("ERROR: arg2 must be a valid 16-bit hex value\n");
+		return;
+	}
+	*(volatile u16 *)(addr + 0xAAA) = 0xAA;
+	*(volatile u16 *)(addr + 0x554) = 0x55;
+	*(volatile u16 *)(addr + 0xAAA) = mode;
+}