logging: add frontend calls in log_core

Call frontend instead of processing if CONFIG_LOG_FRONTEND is enabled.

Signed-off-by: Marcin Szymczyk <Marcin.Szymczyk@nordicsemi.no>

subsys/logging/Kconfig

@@ -14,6 +14,7 @@ if LOG
 
 config LOG_RUNTIME_FILTERING
 	bool "Enable runtime reconfiguration of the logger"
+	depends on !LOG_FRONTEND
 	help
 	  Allow runtime configuration of maximal, independent severity
 	  level for instance.
@@ -68,6 +69,7 @@ config LOG_MAX_LEVEL
 	  - 4 DEBUG, maximal level set to LOG_LEVEL_DBG
 
 menu "Prepend log message with function name"
+	depends on !LOG_FRONTEND
 
 config LOG_FUNC_NAME_PREFIX_ERR
 	bool "Error messages prepended"
@@ -223,6 +225,14 @@ config LOG_CMDS
 	depends on SHELL
 	default y if SHELL
 
+config LOG_FRONTEND
+	bool "Enable frontend"
+	default n
+	select LOG_IMMEDIATE
+	help
+	  When enabled, logs are redirected to a custom frontend instead
+	  of being processed by the logger.
+
 config LOG_BACKEND_UART
 	bool "Enable UART backend"
 	depends on UART_CONSOLE

subsys/logging/log_core.c

@@ -14,6 +14,7 @@
 #include <assert.h>
 #include <sys/atomic.h>
 #include <ctype.h>
+#include <logging/log_frontend.h>
 
 LOG_MODULE_REGISTER(log);
 
@@ -217,24 +218,32 @@ static inline void msg_finalize(struct log_msg *msg,
 
 void log_0(const char *str, struct log_msg_ids src_level)
 {
+	if (IS_ENABLED(CONFIG_LOG_FRONTEND)) {
+		log_frontend_0(str, src_level);
+	} else {
 		struct log_msg *msg = log_msg_create_0(str);
 
 		if (msg == NULL) {
 			return;
 		}
 		msg_finalize(msg, src_level);
+	}
 }
 
 void log_1(const char *str,
 	   log_arg_t arg0,
 	   struct log_msg_ids src_level)
 {
+	if (IS_ENABLED(CONFIG_LOG_FRONTEND)) {
+		log_frontend_1(str, arg0, src_level);
+	} else {
 		struct log_msg *msg = log_msg_create_1(str, arg0);
 
 		if (msg == NULL) {
 			return;
 		}
 		msg_finalize(msg, src_level);
+	}
 }
 
 void log_2(const char *str,
@@ -242,6 +251,9 @@ void log_2(const char *str,
 	   log_arg_t arg1,
 	   struct log_msg_ids src_level)
 {
+	if (IS_ENABLED(CONFIG_LOG_FRONTEND)) {
+		log_frontend_2(str, arg0, arg1, src_level);
+	} else {
 		struct log_msg *msg = log_msg_create_2(str, arg0, arg1);
 
 		if (msg == NULL) {
@@ -249,6 +261,7 @@ void log_2(const char *str,
 		}
 
 		msg_finalize(msg, src_level);
+	}
 }
 
 void log_3(const char *str,
@@ -257,6 +270,9 @@ void log_3(const char *str,
 	   log_arg_t arg2,
 	   struct log_msg_ids src_level)
 {
+	if (IS_ENABLED(CONFIG_LOG_FRONTEND)) {
+		log_frontend_3(str, arg0, arg1, arg2, src_level);
+	} else {
 		struct log_msg *msg = log_msg_create_3(str, arg0, arg1, arg2);
 
 		if (msg == NULL) {
@@ -264,6 +280,7 @@ void log_3(const char *str,
 		}
 
 		msg_finalize(msg, src_level);
+	}
 }
 
 void log_n(const char *str,
@@ -271,6 +288,9 @@ void log_n(const char *str,
 	   u32_t narg,
 	   struct log_msg_ids src_level)
 {
+	if (IS_ENABLED(CONFIG_LOG_FRONTEND)) {
+		log_frontend_n(str, args, narg, src_level);
+	} else {
 		struct log_msg *msg = log_msg_create_n(str, args, narg);
 
 		if (msg == NULL) {
@@ -278,6 +298,7 @@ void log_n(const char *str,
 		}
 
 		msg_finalize(msg, src_level);
+	}
 }
 
 void log_hexdump(const char *str,
@@ -285,6 +306,9 @@ void log_hexdump(const char *str,
 		 u32_t length,
 		 struct log_msg_ids src_level)
 {
+	if (IS_ENABLED(CONFIG_LOG_FRONTEND)) {
+		log_frontend_hexdump(str, data, length, src_level);
+	} else {
 		struct log_msg *msg = log_msg_hexdump_create(str, data, length);
 
 		if (msg == NULL) {
@@ -292,6 +316,7 @@ void log_hexdump(const char *str,
 		}
 
 		msg_finalize(msg, src_level);
+	}
 }
 
 int log_printk(const char *fmt, va_list ap)
@@ -350,7 +375,8 @@ static u32_t count_args(const char *fmt)
 
 void log_generic(struct log_msg_ids src_level, const char *fmt, va_list ap)
 {
-	if (IS_ENABLED(CONFIG_LOG_IMMEDIATE)) {
+	if (IS_ENABLED(CONFIG_LOG_IMMEDIATE) &&
+	    (!IS_ENABLED(CONFIG_LOG_FRONTEND))) {
 		struct log_backend const *backend;
 		u32_t timestamp = timestamp_func();
 
@@ -388,6 +414,9 @@ void log_string_sync(struct log_msg_ids src_level, const char *fmt, ...)
 void log_hexdump_sync(struct log_msg_ids src_level, const char *metadata,
 		      const u8_t *data, u32_t len)
 {
+	if (IS_ENABLED(CONFIG_LOG_FRONTEND)) {
+		log_frontend_hexdump(metadata, data, len, src_level);
+	} else {
 		struct log_backend const *backend;
 		u32_t timestamp = timestamp_func();
 
@@ -400,6 +429,7 @@ void log_hexdump_sync(struct log_msg_ids src_level, const char *metadata,
 							data, len);
 			}
 		}
+	}
 }
 
 static u32_t timestamp_get(void)
@@ -455,6 +485,10 @@ void log_init(void)
 	assert(log_backend_count_get() < LOG_FILTERS_NUM_OF_SLOTS);
 	int i;
 
+	if (IS_ENABLED(CONFIG_LOG_FRONTEND)) {
+		log_frontend_init();
+	}
+
 	if (atomic_inc(&initialized) != 0) {
 		return;
 	}