At present some of the log categories are missing comments. Add them.

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

Add logging to aid debugging features in these drivers. Also drop some
code in sandbox_spi_xfer() which is not used.

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

At present to output a log message you need something like:

   log(UCLASS_SPI, LOCL_INFO, "message1");
   log(UCLASS_SPI, LOCL_INFO, "message2");

but many files use the same category throughout. Also it is helpful to
shorten the length of log names, providing helpers for common logging
levels. Add some macros so that it is possible to do:

   (top of file, before #includes)
   #define LOG_CATEGORY UCLASS_SPI

   (later in the file)
   log_info("message1");
   log_debug("message2");
   log_err("message3");

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

This macro should have two parameters, not one. Fix it so that it
correctly resolves to _ret when logging is disabled.

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

It is sometimes useful to show a message when logging an error return
value, perhaps to add a few details about the problem. Add a function to
support this.

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

This allows access to an element after the end of the array. Fix it.

Reported-by: Coverity (CID: 173279)
Signed-off-by: Simon Glass <sjg@chromium.org>

When U-Boot started using SPDX tags we were among the early adopters and
there weren't a lot of other examples to borrow from.  So we picked the
area of the file that usually had a full license text and replaced it
with an appropriate SPDX-License-Identifier: entry.  Since then, the
Linux Kernel has adopted SPDX tags and they place it as the very first
line in a file (except where shebangs are used, then it's second line)
and with slightly different comment styles than us.

In part due to community overlap, in part due to better tag visibility
and in part for other minor reasons, switch over to that style.

This commit changes all instances where we have a single declared
license in the tag as both the before and after are identical in tag
contents.  There's also a few places where I found we did not have a tag
and have introduced one.

Signed-off-by: Tom Rini <trini@konsulko.com>

According to the documentation the EFI log category is called LOGC_EFI.
All other categories start with LOGC_. So let's fix it.

Fixes: 1973b381a1b3 ("log: add category LOGC_EFI")
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Alexander Graf <agraf@suse.de>

The EFI implementation does not fit into any of the existing categories.

Provide LOGC_EFI so that EFI related message can be filtered.

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

When functions return an error it propagates up the stack to the point
where it is reported. Often the error code provides enough information
about the root cause of the error that this is obvious what went wrong.

However in some cases the error may be hard to trace. For example if a
driver uses several devices to perform an operation, it may not be
obvious which one failed.

Add a log_ret() macro to help with this. This can be used to wrap any
error-return value. The logging system will then output a log record when
the original error is generated, making it easy to trace the call stack
of the error.

This macro can significantly impact code size, so its use is controlled
by a Kconfig option, which is enabled for sandbox.

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