v4.19.13 snapshot.
diff --git a/arch/sh/boot/compressed/cache.c b/arch/sh/boot/compressed/cache.c
new file mode 100644
index 0000000..31e04ff
--- /dev/null
+++ b/arch/sh/boot/compressed/cache.c
@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0
+int cache_control(unsigned int command)
+{
+	volatile unsigned int *p = (volatile unsigned int *) 0x80000000;
+	int i;
+
+	for (i = 0; i < (32 * 1024); i += 32) {
+		(void)*p;
+		p += (32 / sizeof(int));
+	}
+
+	return 0;
+}