log: Add an implementation of logging

Add the logging header file and implementation with some configuration
options to control it.

Signed-off-by: Simon Glass <sjg@chromium.org>

2 files changed, 247 insertions, 0 deletions

diff --git a/include/asm-generic/global_data.h b/include/asm-generic/global_data.h
index 79197acfa4..77755dbb06 100644
--- a/include/asm-generic/global_data.h
+++ b/include/asm-generic/global_data.h
@@ -114,6 +114,11 @@ typedef struct global_data {
 	struct bootstage_data *bootstage;	/* Bootstage information */
 	struct bootstage_data *new_bootstage;	/* Relocated bootstage info */
 #endif
+#ifdef CONFIG_LOG
+	int log_drop_count;		/* Number of dropped log messages */
+	int default_log_level;		/* For devices with no filters */
+	struct list_head log_head;	/* List of struct log_device */
+#endif
 } gd_t;
 #endif
 
diff --git a/include/log.h b/include/log.h
index 08ad44cf49..1e9124c3f8 100644
--- a/include/log.h
+++ b/include/log.h
@@ -10,6 +10,94 @@
 #ifndef __LOG_H
 #define __LOG_H
 
+#include <dm/uclass-id.h>
+#include <linux/list.h>
+
+/** Log levels supported, ranging from most to least important */
+enum log_level_t {
+	LOGL_EMERG = 0,		/*U-Boot is unstable */
+	LOGL_ALERT,		/* Action must be taken immediately */
+	LOGL_CRIT,		/* Critical conditions */
+	LOGL_ERR,		/* Error that prevents something from working */
+	LOGL_WARNING,		/* Warning may prevent optimial operation */
+	LOGL_NOTICE,		/* Normal but significant condition, printf() */
+	LOGL_INFO,		/* General information message */
+	LOGL_DEBUG,		/* Basic debug-level message */
+	LOGL_DEBUG_CONTENT,	/* Debug message showing full message content */
+	LOGL_DEBUG_IO,		/* Debug message showing hardware I/O access */
+
+	LOGL_COUNT,
+	LOGL_FIRST = LOGL_EMERG,
+	LOGL_MAX = LOGL_DEBUG,
+};
+
+/**
+ * Log categories supported. Most of these correspond to uclasses (i.e.
+ * enum uclass_id) but there are also some more generic categories
+ */
+enum log_category_t {
+	LOGC_FIRST = 0,	/* First part mirrors UCLASS_... */
+
+	LOGC_NONE = UCLASS_COUNT,
+	LOGC_ARCH,
+	LOGC_BOARD,
+	LOGC_CORE,
+	LOGC_DT,
+
+	LOGC_COUNT,
+	LOGC_END,
+};
+
+/* Helper to cast a uclass ID to a log category */
+static inline int log_uc_cat(enum uclass_id id)
+{
+	return (enum log_category_t)id;
+}
+
+/**
+ * _log() - Internal function to emit a new log record
+ *
+ * @cat: Category of log record (indicating which subsystem generated it)
+ * @level: Level of log record (indicating its severity)
+ * @file: File name of file where log record was generated
+ * @line: Line number in file where log record was generated
+ * @func: Function where log record was generated
+ * @fmt: printf() format string for log record
+ * @...: Optional parameters, according to the format string @fmt
+ * @return 0 if log record was emitted, -ve on error
+ */
+int _log(enum log_category_t cat, enum log_level_t level, const char *file,
+	 int line, const char *func, const char *fmt, ...);
+
+/* Define this at the top of a file to add a prefix to debug messages */
+#ifndef pr_fmt
+#define pr_fmt(fmt) fmt
+#endif
+
+/* Use a default category if this file does not supply one */
+#ifndef LOG_CATEGORY
+#define LOG_CATEGORY LOGC_NONE
+#endif
+
+/*
+ * This header may be including when CONFIG_LOG is disabled, in which case
+ * CONFIG_LOG_MAX_LEVEL is not defined. Add a check for this.
+ */
+#if CONFIG_IS_ENABLED(LOG)
+#define _LOG_MAX_LEVEL CONFIG_VAL(LOG_MAX_LEVEL)
+#else
+#define _LOG_MAX_LEVEL LOGL_INFO
+#endif
+
+/* Emit a log record if the level is less that the maximum */
+#define log(_cat, _level, _fmt, _args...) ({ \
+	int _l = _level; \
+	if (_l <= _LOG_MAX_LEVEL) \
+		_log((enum log_category_t)(_cat), _l, __FILE__, __LINE__, \
+		      __func__, \
+		      pr_fmt(_fmt), ##_args); \
+	})
+
 #ifdef DEBUG
 #define _DEBUG	1
 #else
@@ -22,6 +110,16 @@
 #define _SPL_BUILD	0
 #endif
 
+#if !_DEBUG && CONFIG_IS_ENABLED(LOG)
+
+#define debug_cond(cond, fmt, args...)			\
+	do {						\
+		if (1)					\
+			log(LOG_CATEGORY, LOGL_DEBUG, fmt, ##args); \
+	} while (0)
+
+#else /* _DEBUG */
+
 /*
  * Output a debug text when condition "cond" is met. The "cond" should be
  * computed by a preprocessor in the best case, allowing for the best
@@ -33,6 +131,8 @@
 			printf(pr_fmt(fmt), ##args);	\
 	} while (0)
 
+#endif /* _DEBUG */
+
 /* Show a message if DEBUG is defined in a file */
 #define debug(fmt, args...)			\
 	debug_cond(_DEBUG, fmt, ##args)
@@ -56,4 +156,146 @@ void __assert_fail(const char *assertion, const char *file, unsigned int line,
 	({ if (!(x) && _DEBUG) \
 		__assert_fail(#x, __FILE__, __LINE__, __func__); })
 
+/**
+ * struct log_rec - a single log record
+ *
+ * Holds information about a single record in the log
+ *
+ * Members marked as 'not allocated' are stored as pointers and the caller is
+ * responsible for making sure that the data pointed to is not overwritten.
+ * Memebers marked as 'allocated' are allocated (e.g. via strdup()) by the log
+ * system.
+ *
+ * @cat: Category, representing a uclass or part of U-Boot
+ * @level: Severity level, less severe is higher
+ * @file: Name of file where the log record was generated (not allocated)
+ * @line: Line number where the log record was generated
+ * @func: Function where the log record was generated (not allocated)
+ * @msg: Log message (allocated)
+ */
+struct log_rec {
+	enum log_category_t cat;
+	enum log_level_t level;
+	const char *file;
+	int line;
+	const char *func;
+	const char *msg;
+};
+
+struct log_device;
+
+/**
+ * struct log_driver - a driver which accepts and processes log records
+ *
+ * @name: Name of driver
+ */
+struct log_driver {
+	const char *name;
+	/**
+	 * emit() - emit a log record
+	 *
+	 * Called by the log system to pass a log record to a particular driver
+	 * for processing. The filter is checked before calling this function.
+	 */
+	int (*emit)(struct log_device *ldev, struct log_rec *rec);
+};
+
+/**
+ * struct log_device - an instance of a log driver
+ *
+ * Since drivers are set up at build-time we need to have a separate device for
+ * the run-time aspects of drivers (currently just a list of filters to apply
+ * to records send to this device).
+ *
+ * @next_filter_num: Seqence number of next filter filter added (0=no filters
+ *	yet). This increments with each new filter on the device, but never
+ *	decrements
+ * @drv: Pointer to driver for this device
+ * @filter_head: List of filters for this device
+ * @sibling_node: Next device in the list of all devices
+ */
+struct log_device {
+	int next_filter_num;
+	struct log_driver *drv;
+	struct list_head filter_head;
+	struct list_head sibling_node;
+};
+
+enum {
+	LOGF_MAX_CATEGORIES = 5,	/* maximum categories per filter */
+};
+
+enum log_filter_flags {
+	LOGFF_HAS_CAT		= 1 << 0,	/* Filter has a category list */
+};
+
+/**
+ * struct log_filter - criterial to filter out log messages
+ *
+ * @filter_num: Sequence number of this filter.  This is returned when adding a
+ *	new filter, and must be provided when removing a previously added
+ *	filter.
+ * @flags: Flags for this filter (LOGFF_...)
+ * @cat_list: List of categories to allow (terminated by LOGC_none). If empty
+ *	then all categories are permitted. Up to LOGF_MAX_CATEGORIES entries
+ *	can be provided
+ * @max_level: Maximum log level to allow
+ * @file_list: List of files to allow, separated by comma. If NULL then all
+ *	files are permitted
+ * @sibling_node: Next filter in the list of filters for this log device
+ */
+struct log_filter {
+	int filter_num;
+	int flags;
+	enum log_category_t cat_list[LOGF_MAX_CATEGORIES];
+	enum log_level_t max_level;
+	const char *file_list;
+	struct list_head sibling_node;
+};
+
+#define LOG_DRIVER(_name) \
+	ll_entry_declare(struct log_driver, _name, log_driver)
+
+/**
+ * log_add_filter() - Add a new filter to a log device
+ *
+ * @drv_name: Driver name to add the filter to (since each driver only has a
+ *	single device)
+ * @cat_list: List of categories to allow (terminated by LOGC_none). If empty
+ *	then all categories are permitted. Up to LOGF_MAX_CATEGORIES entries
+ *	can be provided
+ * @max_level: Maximum log level to allow
+ * @file_list: List of files to allow, separated by comma. If NULL then all
+ *	files are permitted
+ * @return the sequence number of the new filter (>=0) if the filter was added,
+ *	or a -ve value on error
+ */
+int log_add_filter(const char *drv_name, enum log_category_t cat_list[],
+		   enum log_level_t max_level, const char *file_list);
+
+/**
+ * log_remove_filter() - Remove a filter from a log device
+ *
+ * @drv_name: Driver name to remove the filter from (since each driver only has
+ *	a single device)
+ * @filter_num: Filter number to remove (as returned by log_add_filter())
+ * @return 0 if the filter was removed, -ENOENT if either the driver or the
+ *	filter number was not found
+ */
+int log_remove_filter(const char *drv_name, int filter_num);
+
+#if CONFIG_IS_ENABLED(LOG)
+/**
+ * log_init() - Set up the log system ready for use
+ *
+ * @return 0 if OK, -ENOMEM if out of memory
+ */
+int log_init(void);
+#else
+static inline int log_init(void)
+{
+	return 0;
+}
+#endif
+
 #endif