examples: add initial examples for RFC

Add hello_world and random(generate UUID) examples

Reviewed-by: Etienne Carriere <etienne.carriere@linaro.org>
Reviewed-by: Jerome Forissier <jerome.forissier@linaro.org>
Signed-off-by: Igor Opaniuk <igor.opaniuk@linaro.org>
diff --git a/random/host/main.c b/random/host/main.c
new file mode 100644
index 0000000..5ad9de0
--- /dev/null
+++ b/random/host/main.c
@@ -0,0 +1,112 @@
+/*
+ * Copyright (c) 2016, Linaro Limited
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <err.h>
+#include <stdio.h>
+#include <string.h>
+
+/* OP-TEE TEE client API (built by optee_client) */
+#include <tee_client_api.h>
+
+/* To the the UUID (found the the TA's h-file(s)) */
+#include <random_example_ta.h>
+
+int main(int argc, char *argv[])
+{
+	TEEC_Result res;
+	TEEC_Context ctx;
+	TEEC_Session sess;
+	TEEC_Operation op = { 0 };
+	TEEC_UUID uuid = TA_RANDOM_EXAMPLE_UUID;
+	uint8_t random_uuid[16] = { 0 };
+	uint32_t err_origin;
+
+	/* Initialize a context connecting us to the TEE */
+	res = TEEC_InitializeContext(NULL, &ctx);
+	if (res != TEEC_SUCCESS)
+		errx(1, "TEEC_InitializeContext failed with code 0x%x", res);
+
+	/*
+	 * Open a session to the Random example TA, the TA will print "hello
+	 * world!" in the log when the session is created.
+	 */
+	res = TEEC_OpenSession(&ctx, &sess, &uuid,
+			       TEEC_LOGIN_PUBLIC, NULL, NULL, &err_origin);
+	if (res != TEEC_SUCCESS)
+		errx(1, "TEEC_Opensession failed with code 0x%x origin 0x%x",
+			res, err_origin);
+
+	/*
+	 * Execute a function in the TA by invoking it, in this case
+	 * we're incrementing a number.
+	 *
+	 * The value of command ID part and how the parameters are
+	 * interpreted is part of the interface provided by the TA.
+	 */
+
+	/* Clear the TEEC_Operation struct */
+	memset(&op, 0, sizeof(op));
+
+	/*
+	 * Prepare the argument. Pass a value in the first parameter,
+	 * the remaining three parameters are unused.
+	 */
+	op.paramTypes = TEEC_PARAM_TYPES(TEEC_MEMREF_TEMP_OUTPUT, TEEC_NONE,
+					 TEEC_NONE, TEEC_NONE);
+	op.params[0].tmpref.buffer = random_uuid;
+	op.params[0].tmpref.size = sizeof(random_uuid);
+
+	/*
+	 * TA_EXAMPLE_RANDOM_GENERATE is the actual function in the TA to be
+	 * called.
+	 */
+	printf("Invoking TA to generate random UUID... \n");
+	res = TEEC_InvokeCommand(&sess, TA_EXAMPLE_RANDOM_GENERATE, &op,
+				 &err_origin);
+	if (res != TEEC_SUCCESS)
+		errx(1, "TEEC_InvokeCommand failed with code 0x%x origin 0x%x",
+			res, err_origin);
+
+	printf("TA generated UUID value = 0x");
+	for (int i = 0; i < 16; i++)
+		printf("%x", random_uuid[i]);
+	printf("\n");
+
+	/*
+	 * We're done with the TA, close the session and
+	 * destroy the context.
+	 *
+	 * The TA will print "Goodbye!" in the log when the
+	 * session is closed.
+	 */
+
+	TEEC_CloseSession(&sess);
+
+	TEEC_FinalizeContext(&ctx);
+
+	return 0;
+}