hotp: Initial commit for HMAC-OTP (RFC4226)

Add host application and a new TA that are capable of generating HMAC
based One Time Passwords according to the RFC4226 specification [1].

[1] https://www.ietf.org/rfc/rfc4226.txt

Signed-off-by: Joakim Bech <joakim.bech@linaro.org>
Tested-by: Joakim Bech <joakim.bech@linaro.org> (QEMU v7)
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>
diff --git a/hotp/host/Makefile b/hotp/host/Makefile
new file mode 100644
index 0000000..ce7065f
--- /dev/null
+++ b/hotp/host/Makefile
@@ -0,0 +1,25 @@
+CC      = $(CROSS_COMPILE)gcc
+LD      = $(CROSS_COMPILE)ld
+AR      = $(CROSS_COMPILE)ar
+NM      = $(CROSS_COMPILE)nm
+OBJCOPY = $(CROSS_COMPILE)objcopy
+OBJDUMP = $(CROSS_COMPILE)objdump
+READELF = $(CROSS_COMPILE)readelf
+
+OBJS = main.o
+
+CFLAGS += -Wall -I../ta/include -I./include
+CFLAGS += -I$(TEEC_EXPORT)/include
+LDADD += -lteec -L$(TEEC_EXPORT)/lib
+
+BINARY = optee_example_hotp
+
+.PHONY: all
+all: $(BINARY)
+
+$(BINARY): $(OBJS)
+	$(CC) -o $@ $< $(LDADD)
+
+.PHONY: clean
+clean:
+	rm -f $(OBJS) $(BINARY)