spl: Add support for logging in SPL and TPL

It is sometimes useful to log information in SPL and TPL. Add support for
this.

Reviewed-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Simon Glass <sjg@chromium.org>

common/Kconfig

@@ -299,6 +299,10 @@ config SPL_LOGLEVEL
 	int
 	default LOGLEVEL
 
+config TPL_LOGLEVEL
+	int
+	default LOGLEVEL
+
 config SILENT_CONSOLE
 	bool "Support a silent console"
 	help
@@ -505,6 +509,24 @@ config SPL_LOG_MAX_LEVEL
 	    6 - detail
 	    7 - debug
 
+config TPL_LOG_MAX_LEVEL
+	int "Maximum log level to record in TPL"
+	depends on TPL_LOG
+	default 3
+	help
+	  This selects the maximum log level that will be recorded. Any value
+	  higher than this will be ignored. If possible log statements below
+	  this level will be discarded at build time. Levels:
+
+	    0 - panic
+	    1 - critical
+	    2 - error
+	    3 - warning
+	    4 - note
+	    5 - info
+	    6 - detail
+	    7 - debug
+
 config LOG_CONSOLE
 	bool "Allow log output to the console"
 	depends on LOG
@@ -515,9 +537,19 @@ config LOG_CONSOLE
 	  log message is shown - other details like level, category, file and
 	  line number are omitted.
 
-config LOG_SPL_CONSOLE
+config SPL_LOG_CONSOLE
 	bool "Allow log output to the console in SPL"
-	depends on LOG_SPL
+	depends on SPL_LOG
+	default y
+	help
+	  Enables a log driver which writes log records to the console.
+	  Generally the console is the serial port or LCD display. Only the
+	  log message is shown - other details like level, category, file and
+	  line number are omitted.
+
+config TPL_LOG_CONSOLE
+	bool "Allow log output to the console in SPL"
+	depends on TPL_LOG
 	default y
 	help
 	  Enables a log driver which writes log records to the console.

common/Makefile

@@ -122,8 +122,8 @@ obj-y += cli.o
 obj-$(CONFIG_FSL_DDR_INTERACTIVE) += cli_simple.o cli_readline.o
 obj-$(CONFIG_DFU_OVER_USB) += dfu.o
 obj-y += command.o
-obj-$(CONFIG_$(SPL_)LOG) += log.o
-obj-$(CONFIG_$(SPL_)LOG_CONSOLE) += log_console.o
+obj-$(CONFIG_$(SPL_TPL_)LOG) += log.o
+obj-$(CONFIG_$(SPL_TPL_)LOG_CONSOLE) += log_console.o
 obj-y += s_record.o
 obj-$(CONFIG_CMD_LOADB) += xyzModem.o
 obj-$(CONFIG_$(SPL_TPL_)YMODEM_SUPPORT) += xyzModem.o

common/spl/spl.c

@@ -336,6 +336,13 @@ static int spl_common_init(bool setup_malloc)
 		return ret;
 	}
 	bootstage_mark_name(BOOTSTAGE_ID_START_SPL, "spl");
+#if CONFIG_IS_ENABLED(LOG)
+	ret = log_init();
+	if (ret) {
+		debug("%s: Failed to set up logging\n", __func__);
+		return ret;
+	}
+#endif
 	if (CONFIG_IS_ENABLED(OF_CONTROL) && !CONFIG_IS_ENABLED(OF_PLATDATA)) {
 		ret = fdtdec_setup();
 		if (ret) {

include/log.h

@@ -108,6 +108,8 @@ int _log(enum log_category_t cat, enum log_level_t level, const char *file,
 #define log_io(_fmt...)
 #endif
 
+#if CONFIG_IS_ENABLED(LOG)
+
 /* Emit a log record if the level is less that the maximum */
 #define log(_cat, _level, _fmt, _args...) ({ \
 	int _l = _level; \
@@ -116,6 +118,9 @@ int _log(enum log_category_t cat, enum log_level_t level, const char *file,
 		      __func__, \
 		      pr_fmt(_fmt), ##_args); \
 	})
+#else
+#define log(_cat, _level, _fmt, _args...)
+#endif
 
 #ifdef DEBUG
 #define _DEBUG	1
@@ -175,7 +180,16 @@ void __assert_fail(const char *assertion, const char *file, unsigned int line,
 	({ if (!(x) && _DEBUG) \
 		__assert_fail(#x, __FILE__, __LINE__, __func__); })
 
-#ifdef CONFIG_LOG_ERROR_RETURN
+#if CONFIG_IS_ENABLED(LOG) && defined(CONFIG_LOG_ERROR_RETURN)
+/*
+ * Log an error return value, possibly with a message. Usage:
+ *
+ *	return log_ret(fred_call());
+ *
+ * or:
+ *
+ *	return log_msg_ret("fred failed", fred_call());
+ */
 #define log_ret(_ret) ({ \
 	int __ret = (_ret); \
 	if (__ret < 0) \
@@ -190,8 +204,9 @@ void __assert_fail(const char *assertion, const char *file, unsigned int line,
 	__ret; \
 	})
 #else
+/* Non-logging versions of the above which just return the error code */
 #define log_ret(_ret) (_ret)
-#define log_msg_ret(_msg, _ret) (_ret)
+#define log_msg_ret(_msg, _ret) ((void)(_msg), _ret)
 #endif
 
 /**