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

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

Changes in v4:
- Add an extra tab in the debug_cond() macro
- Handle casting uclass ID to lgo category (for clang)

Changes in v3: None
Changes in v2:
- Add a comment as to why CONFIG_LOG_MAX_LEVEL is not defined
- Drop MAINTAINERS entries for files not added by this patch
- Drop the use of 'continue' in the macro
- Fix LOG_SPL_MAX_LEVEL typo (should be SPL_LOG_MAX_LEVEL)
- Fix up bad use of #if CONFIG_VAL() - use #ifdef instead
- Line up log levels with Linux

 MAINTAINERS                       |   7 ++
 common/Kconfig                    |  56 +++++++++
 common/Makefile                   |   1 +
 common/log.c                      | 244 ++++++++++++++++++++++++++++++++++++++
 include/asm-generic/global_data.h |   5 +
 include/log.h                     | 242 +++++++++++++++++++++++++++++++++++++
 6 files changed, 555 insertions(+)
 create mode 100644 common/log.c

diff --git a/MAINTAINERS b/MAINTAINERS
index c024b41f13..7cda6896ea 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -310,6 +310,13 @@ S: Maintained
 T:     git git://git.denx.de/u-boot-i2c.git
 F:     drivers/i2c/
 
+LOGGING
+M:     Simon Glass <s...@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 <mon...@monstr.eu>
 S:     Maintained
diff --git a/common/Kconfig b/common/Kconfig
index c50d6ebb2a..9747443feb 100644
--- a/common/Kconfig
+++ b/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
diff --git a/common/Makefile b/common/Makefile
index cec506fe3e..f4b632761f 100644
--- a/common/Makefile
+++ b/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
diff --git a/common/log.c b/common/log.c
new file mode 100644
index 0000000000..8f36c79c26
--- /dev/null
+++ b/common/log.c
@@ -0,0 +1,244 @@
+/*
+ * Logging support
+ *
+ * Copyright (c) 2017 Google, Inc
+ * Written by Simon Glass <s...@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;
+}
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
-- 
2.15.0.531.g2ccb3012c9-goog

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