Sphinx 3 builds fail due to doc/develop/logging.rst producing duplicate
labels.

Include logging.h only once in the API section and use cross-references for
the enums log_level_t and log_category_t.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

This updates logging documentation with some examples of the new commands
added in the previous commits. It also removes some items from the to-do
list which have been implemented.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

The functions in log.h are already mostly documented, so add them to the
generated documentation.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

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@gmx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>

Fix up the documentation which was lost in a merge conflict in the
conversion to RST.

Fixes: 52d3df7fefe ("log: Allow LOG_DEBUG to always enable log output")

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

Convert README.log to reStructuredText and add it to the generated HTML
documentation.

Assign doc/develop/logging.rst to the maintainer of LOGGING.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>