[PATCH 1/2] log: allow for message continuation

[Heinrich Schuchardt]

Some drivers use macro pr_cont() for continuing a message sent via printk.
Hence if we want to convert printk messaging to using the logging system,
we must support continuation of log messages too.

As pr_cont() does not provide a message level we need a means of
remembering the last log level.

With the patch a pseudo log level LOGL_CONT as well as a pseudo log
category LOGC_CONT are introduced. Using these results in the application
of the same log level and category as in the previous log message.

Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
---
 common/log.c            | 23 ++++++++++++++++++-----
 doc/develop/logging.rst |  6 ++++++
 include/log.h           |  2 ++
 3 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/common/log.c b/common/log.c
index 9a5f100da3..bafc09f263 100644
--- a/common/log.c
+++ b/common/log.c
@@ -183,10 +183,12 @@ static bool log_passes_filters(struct log_device *ldev, struct log_rec *rec)
  * 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
+ * filters which block the record.
  *
- * @rec: Log record to dispatch
- * @return 0 (meaning success)
+ * All log messages created while processing log record @rec are ignored.
+ *
+ * @rec:	log record to dispatch
+ * Return:	0 msg sent, 1 msg not sent while already dispatching another msg
  */
 static int log_dispatch(struct log_rec *rec)
 {
@@ -199,7 +201,7 @@ static int log_dispatch(struct log_rec *rec)
 	 * as this might result in infinite recursion.
 	 */
 	if (processing_msg)
-		return 0;
+		return 1;

 	/* Emit message */
 	processing_msg = 1;
@@ -214,10 +216,18 @@ static int log_dispatch(struct log_rec *rec)
 int _log(enum log_category_t cat, enum log_level_t level, const char *file,
 	 int line, const char *func, const char *fmt, ...)
 {
+	static enum log_category_t logc_prev = LOGC_NONE;
+	static enum log_level_t logl_prev = LOGL_INFO;
 	char buf[CONFIG_SYS_CBSIZE];
 	struct log_rec rec;
 	va_list args;

+	/* Check for message continuation */
+	if (cat == LOGC_CONT)
+		cat = logc_prev;
+	if (level == LOGL_CONT)
+		level = logl_prev;
+
 	rec.cat = cat;
 	rec.level = level;
 	rec.file = file;
@@ -232,7 +242,10 @@ int _log(enum log_category_t cat, enum log_level_t level, const char *file,
 			gd->log_drop_count++;
 		return -ENOSYS;
 	}
-	log_dispatch(&rec);
+	if (!log_dispatch(&rec)) {
+		logc_prev = cat;
+		logl_prev = level;
+	}

 	return 0;
 }
diff --git a/doc/develop/logging.rst b/doc/develop/logging.rst
index 7ce8482ab6..c36f6bbbe4 100644
--- a/doc/develop/logging.rst
+++ b/doc/develop/logging.rst
@@ -38,6 +38,9 @@ There are a number logging levels available, in increasing order of verbosity:
 * LOGL_DEBUG_CONTENT - Debug message showing full message content
 * LOGL_DEBUG_IO - Debug message showing hardware I/O access

+To continue a log message in a separate call of function log() use
+
+* LOGL_CONT - Use same log level as in previous call

 Logging category
 ----------------
@@ -56,6 +59,9 @@ The following main categories are defined:
 * LOGC_DT - Related to device tree control
 * LOGC_EFI - Related to EFI implementation

+To continue a log message in a separate call of function log() use
+
+* LOGC_CONT - Use same category as in previous call

 Enabling logging
 ----------------
diff --git a/include/log.h b/include/log.h
index 2859ce1f2e..567cd32d34 100644
--- a/include/log.h
+++ b/include/log.h
@@ -35,6 +35,7 @@ enum log_level_t {

 	LOGL_FIRST = LOGL_EMERG,
 	LOGL_MAX = LOGL_DEBUG_IO,
+	LOGL_CONT = -1,		/* Use same log level as in previous call */
 };

 /**
@@ -60,6 +61,7 @@ enum log_category_t {

 	LOGC_COUNT,	/* Number of log categories */
 	LOGC_END,	/* Sentinel value for a list of log categories */
+	LOGC_CONT = -1,	/* Use same category as in previous call */
 };

 /* Helper to cast a uclass ID to a log category */
--
2.28.0