dt: dt-extract-compatibles: Don't follow symlinks when walking tree

The iglob function, which we use to find C source files in the kernel
tree, always follows symbolic links. This can cause unintentional
recursions whenever a symbolic link points to a parent directory. A
common scenario is building the kernel with the output set to a
directory inside the kernel tree, which will contain such a symlink.

Instead of using the iglob function, use os.walk to traverse the
directory tree, which by default doesn't follow symbolic links. fnmatch
is then used to match the glob on the filename, as well as ignore hidden
files (which were ignored by default with iglob).

This approach runs just as fast as using iglob.

Fixes: b6acf8073517 ("dt: Add a check for undocumented compatible strings in kernel")
Reported-by: Aishwarya TCV <aishwarya.tcv@arm.com>
Closes: https://lore.kernel.org/all/e90cb52f-d55b-d3ba-3933-6cc7b43fcfbc@arm.com
Signed-off-by: "Nícolas F. R. A. Prado" <nfraprado@collabora.com>
Link: https://lore.kernel.org/r/20231107225624.9811-1-nfraprado@collabora.com
Signed-off-by: Rob Herring <robh@kernel.org>

dt: dt-extract-compatibles: Add flag for driver matching compatibles

Add a new flag, '--driver-match', to the dt-extract-compatibles script
that causes it to only print out compatibles that are expected to match
a driver. This output can then be used by tests to detect device probe
failures.

In order to filter the compatibles down to only ones that will match to
a driver, the following is considered:
- A compatible needs to show up in a driver's of_match_table for it to
be matched to a driver
- Compatibles that are used in both of_match_table and OF_DECLARE type
macros can't be expected to match to a driver and so are ignored.
One exception is CLK_OF_DECLARE_DRIVER, since it indicates that a
driver will also later probe, so compatibles in this macro are not
ignored.

Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Link: https://lore.kernel.org/r/20230828211424.2964562-3-nfraprado@collabora.com
Signed-off-by: Rob Herring <robh@kernel.org>

dt: dt-extract-compatibles: Handle cfile arguments in generator function

Move the handling of the cfile arguments to a separate generator
function to avoid redundancy.

Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Link: https://lore.kernel.org/r/20230828211424.2964562-2-nfraprado@collabora.com
Signed-off-by: Rob Herring <robh@kernel.org>

dt: dt-check-compatible: Find struct of_device_id instances with compiler annotations

The regex search for declarations of struct of_device_id was missing
cases that had a compiler annotation such as "__maybe_unused". Improve
the regex to allow for these. Use '\S' instead of specific characters to
shorten the regex. That also finds some more compatibles using '.'
characters.

Unfortunately, these changes add ~400 more compatibles without a
schema.

Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230804190130.1936566-1-robh@kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>

dt: Add a check for undocumented compatible strings in kernel

Add a make target, dt_compatible_check, to extract compatible strings
from kernel sources and check if they are documented by a schema.
At least version v2022.08 of dtschema with dt-check-compatible is
required.

This check can also be run manually on specific files or directories:

scripts/dtc/dt-extract-compatibles drivers/clk/ | \
xargs dt-check-compatible -v -s Documentation/devicetree/bindings/processed-schema.json

Currently, there are about 3800 undocumented compatible strings. Most of
these are cases where the binding is not yet converted (given there
are 1900 .txt binding files remaining).

Link: https://lore.kernel.org/all/20220916012510.2718170-1-robh@kernel.org/
Signed-off-by: Rob Herring <robh@kernel.org>