qemu: Add support for Trusted Board Boot

This patch adds support for TBB to qemu. An RSA ROT keypair is generated at
build time and is included into BL1/BL2. The key and content certificates
are read over semihosting.

Fixes ARM-software/tf-issues#526

Signed-off-by: Michalis Pappas <mpappas@fastmail.fm>
diff --git a/plat/qemu/qemu_trusted_boot.c b/plat/qemu/qemu_trusted_boot.c
new file mode 100644
index 0000000..7d8fed2
--- /dev/null
+++ b/plat/qemu/qemu_trusted_boot.c
@@ -0,0 +1,31 @@
+/*
+ * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <platform.h>
+
+extern char qemu_rotpk_hash[], qemu_rotpk_hash_end[];
+
+int plat_get_rotpk_info(void *cookie, void **key_ptr, unsigned int *key_len,
+			unsigned int *flags)
+{
+	*key_ptr = qemu_rotpk_hash;
+	*key_len = qemu_rotpk_hash_end - qemu_rotpk_hash;
+	*flags = ROTPK_IS_HASH;
+
+	return 0;
+}
+
+int plat_get_nv_ctr(void *cookie, unsigned int *nv_ctr)
+{
+	*nv_ctr = 0;
+
+	return 0;
+}
+
+int plat_set_nv_ctr(void *cookie, unsigned int nv_ctr)
+{
+	return 1;
+}