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>

MAINTAINERS

@@ -310,6 +310,13 @@ S:	Maintained
 T:	git git://git.denx.de/u-boot-i2c.git
 F:	drivers/i2c/
 
+LOGGING
+M:	Simon Glass <sjg@chromium.org>
+S:	Maintained
+T:	git git://git.denx.de/u-boot.git
+F:	common/log.c
+F:	cmd/log.c
+
 MICROBLAZE
 M:	Michal Simek <monstr@monstr.eu>
 S:	Maintained

common/Kconfig

@@ -420,6 +420,62 @@ config SYS_STDIO_DEREGISTER
 
 endmenu
 
+menu "Logging"
+
+config LOG
+	bool "Enable logging support"
+	help
+	  This enables support for logging of status and debug messages. These
+	  can be displayed on the console, recorded in a memory buffer, or
+	  discarded if not needed. Logging supports various categories and
+	  levels of severity.
+
+config SPL_LOG
+	bool "Enable logging support in SPL"
+	help
+	  This enables support for logging of status and debug messages. These
+	  can be displayed on the console, recorded in a memory buffer, or
+	  discarded if not needed. Logging supports various categories and
+	  levels of severity.
+
+config LOG_MAX_LEVEL
+	int "Maximum log level to record"
+	depends on LOG
+	default 5
+	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 SPL_LOG_MAX_LEVEL
+	int "Maximum log level to record in SPL"
+	depends on SPL_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
+
+endmenu
+
 config DEFAULT_FDT_FILE
 	string "Default fdt file"
 	help

common/Makefile

@@ -128,5 +128,6 @@ obj-y += cli.o
 obj-$(CONFIG_FSL_DDR_INTERACTIVE) += cli_simple.o cli_readline.o
 obj-$(CONFIG_CMD_DFU) += dfu.o
 obj-y += command.o
+obj-$(CONFIG_$(SPL_)LOG) += log.o
 obj-y += s_record.o
 obj-y += xyzModem.o

common/log.c

@@ -0,0 +1,244 @@
+/*
+ * Logging support
+ *
+ * Copyright (c) 2017 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <log.h>
+#include <malloc.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+static struct log_device *log_device_find_by_name(const char *drv_name)
+{
+	struct log_device *ldev;
+
+	list_for_each_entry(ldev, &gd->log_head, sibling_node) {
+		if (!strcmp(drv_name, ldev->drv->name))
+			return ldev;
+	}
+
+	return NULL;
+}
+
+/**
+ * log_has_cat() - check if a log category exists within a list
+ *
+ * @cat_list: List of categories to check, at most LOGF_MAX_CATEGORIES entries
+ *	long, terminated by LC_END if fewer
+ * @cat: Category to search for
+ * @return true if @cat is in @cat_list, else false
+ */
+static bool log_has_cat(enum log_category_t cat_list[], enum log_category_t cat)
+{
+	int i;
+
+	for (i = 0; i < LOGF_MAX_CATEGORIES && cat_list[i] != LOGC_END; i++) {
+		if (cat_list[i] == cat)
+			return true;
+	}
+
+	return false;
+}
+
+/**
+ * log_has_file() - check if a file is with a list
+ *
+ * @file_list: List of files to check, separated by comma
+ * @file: File to check for. This string is matched against the end of each
+ *	file in the list, i.e. ignoring any preceding path. The list is
+ *	intended to consist of relative pathnames, e.g. common/main.c,cmd/log.c
+ * @return true if @file is in @file_list, else false
+ */
+static bool log_has_file(const char *file_list, const char *file)
+{
+	int file_len = strlen(file);
+	const char *s, *p;
+	int substr_len;
+
+	for (s = file_list; *s; s = p + (*p != '\0')) {
+		p = strchrnul(s, ',');
+		substr_len = p - s;
+		if (file_len >= substr_len &&
+		    !strncmp(file + file_len - substr_len, s, substr_len))
+			return true;
+	}
+
+	return false;
+}
+
+/**
+ * log_passes_filters() - check if a log record passes the filters for a device
+ *
+ * @ldev: Log device to check
+ * @rec: Log record to check
+ * @return true if @rec is not blocked by the filters in @ldev, false if it is
+ */
+static bool log_passes_filters(struct log_device *ldev, struct log_rec *rec)
+{
+	struct log_filter *filt;
+
+	/* If there are no filters, filter on the default log level */
+	if (list_empty(&ldev->filter_head)) {
+		if (rec->level > gd->default_log_level)
+			return false;
+		return true;
+	}
+
+	list_for_each_entry(filt, &ldev->filter_head, sibling_node) {
+		if (rec->level > filt->max_level)
+			continue;
+		if ((filt->flags & LOGFF_HAS_CAT) &&
+		    !log_has_cat(filt->cat_list, rec->cat))
+			continue;
+		if (filt->file_list &&
+		    !log_has_file(filt->file_list, rec->file))
+			continue;
+		return true;
+	}
+
+	return false;
+}
+
+/**
+ * log_dispatch() - Send a log record to all log devices for processing
+ *
+ * The log record is sent to each log device in turn, skipping those which have
+ * filters which block the record
+ *
+ * @rec: Log record to dispatch
+ * @return 0 (meaning success)
+ */
+static int log_dispatch(struct log_rec *rec)
+{
+	struct log_device *ldev;
+
+	list_for_each_entry(ldev, &gd->log_head, sibling_node) {
+		if (log_passes_filters(ldev, rec))
+			ldev->drv->emit(ldev, rec);
+	}
+
+	return 0;
+}
+
+int _log(enum log_category_t cat, enum log_level_t level, const char *file,
+	 int line, const char *func, const char *fmt, ...)
+{
+	char buf[CONFIG_SYS_CBSIZE];
+	struct log_rec rec;
+	va_list args;
+
+	rec.cat = cat;
+	rec.level = level;
+	rec.file = file;
+	rec.line = line;
+	rec.func = func;
+	va_start(args, fmt);
+	vsnprintf(buf, sizeof(buf), fmt, args);
+	va_end(args);
+	rec.msg = buf;
+	if (!gd || !(gd->flags & GD_FLG_LOG_READY)) {
+		if (gd)
+			gd->log_drop_count++;
+		return -ENOSYS;
+	}
+	log_dispatch(&rec);
+
+	return 0;
+}
+
+int log_add_filter(const char *drv_name, enum log_category_t cat_list[],
+		   enum log_level_t max_level, const char *file_list)
+{
+	struct log_filter *filt;
+	struct log_device *ldev;
+	int i;
+
+	ldev = log_device_find_by_name(drv_name);
+	if (!ldev)
+		return -ENOENT;
+	filt = (struct log_filter *)calloc(1, sizeof(*filt));
+	if (!filt)
+		return -ENOMEM;
+
+	if (cat_list) {
+		filt->flags |= LOGFF_HAS_CAT;
+		for (i = 0; ; i++) {
+			if (i == ARRAY_SIZE(filt->cat_list))
+				return -ENOSPC;
+			filt->cat_list[i] = cat_list[i];
+			if (cat_list[i] == LOGC_END)
+				break;
+		}
+	}
+	filt->max_level = max_level;
+	if (file_list) {
+		filt->file_list = strdup(file_list);
+		if (!filt->file_list)
+			goto nomem;
+	}
+	filt->filter_num = ldev->next_filter_num++;
+	list_add_tail(&filt->sibling_node, &ldev->filter_head);
+
+	return filt->filter_num;
+
+nomem:
+	free(filt);
+	return -ENOMEM;
+}
+
+int log_remove_filter(const char *drv_name, int filter_num)
+{
+	struct log_filter *filt;
+	struct log_device *ldev;
+
+	ldev = log_device_find_by_name(drv_name);
+	if (!ldev)
+		return -ENOENT;
+
+	list_for_each_entry(filt, &ldev->filter_head, sibling_node) {
+		if (filt->filter_num == filter_num) {
+			list_del(&filt->sibling_node);
+			free(filt);
+
+			return 0;
+		}
+	}
+
+	return -ENOENT;
+}
+
+int log_init(void)
+{
+	struct log_driver *drv = ll_entry_start(struct log_driver, log_driver);
+	const int count = ll_entry_count(struct log_driver, log_driver);
+	struct log_driver *end = drv + count;
+
+	/*
+	 * We cannot add runtime data to the driver since it is likely stored
+	 * in rodata. Instead, set up a 'device' corresponding to each driver.
+	 * We only support having a single device.
+	 */
+	INIT_LIST_HEAD((struct list_head *)&gd->log_head);
+	while (drv < end) {
+		struct log_device *ldev;
+
+		ldev = calloc(1, sizeof(*ldev));
+		if (!ldev) {
+			debug("%s: Cannot allocate memory\n", __func__);
+			return -ENOMEM;
+		}
+		INIT_LIST_HEAD(&ldev->filter_head);
+		ldev->drv = drv;
+		list_add_tail(&ldev->sibling_node,
+			      (struct list_head *)&gd->log_head);
+		drv++;
+	}
+	gd->default_log_level = LOGL_INFO;
+
+	return 0;
+}

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
 

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