[Review] drivers: Implement semihosting based console driver for log

Add #ifdef guard for semihosting_console_init() to avoid potential link
error when CFG_SEMIHOSTING_CONSOLE is not enabled.

Add checking on CFG_SEMIHOSTING_CONSOLE_FILE.

Signed-off-by: Alvin Chang <alvinga@andestech.com>

core/include/drivers/semihosting_console.h

@@ -5,6 +5,7 @@
 #ifndef __DRIVERS_SEMIHOSTING_CONSOLE_H
 #define __DRIVERS_SEMIHOSTING_CONSOLE_H
 
+#ifdef CFG_SEMIHOSTING_CONSOLE
 /*
  * Initialize console which uses architecture-specific semihosting mechanism.
  * If @file_path is not NULL, OP-TEE OS will try to output log to that file,
@@ -13,5 +14,10 @@
  * semihosting host debug console.
  */
 void semihosting_console_init(const char *file_path);
+#else
+static inline void semihosting_console_init(const char *file_path __unused)
+{
+}
+#endif
 
 #endif /* __DRIVERS_SEMIHOSTING_CONSOLE_H */

mk/config.mk

@@ -1166,12 +1166,15 @@ CFG_SEMIHOSTING ?= n
 
 # Enable the semihosting console driver which inputs/outputs the characters
 # from/to the file or debug terminal on the semihosting host computer.
-#   - Specify CFG_SEMIHOSTING_CONSOLE_FILE="{your_log_file}" to output the
-#     characters to that file. Output to "optee.log" by default.
-#   - Specify CFG_SEMIHOSTING_CONSOLE_FILE=NULL to output the characters to the
-#     semihosting host terminal.
+# - Specify CFG_SEMIHOSTING_CONSOLE_FILE="{your_log_file}" to output the
+#   characters to that file. Output to "optee.log" by default.
+# - Specify CFG_SEMIHOSTING_CONSOLE_FILE=NULL to output the characters to the
+#   semihosting host terminal.
 CFG_SEMIHOSTING_CONSOLE ?= n
 ifeq ($(CFG_SEMIHOSTING_CONSOLE),y)
 $(call force,CFG_SEMIHOSTING,y)
 endif
 CFG_SEMIHOSTING_CONSOLE_FILE ?= "optee.log"
+ifeq ($(CFG_SEMIHOSTING_CONSOLE_FILE),)
+$(error CFG_SEMIHOSTING_CONSOLE_FILE cannot be empty)
+endif