[PATCH] checkpatch: check proper licensing of Devicetree bindings

[Lubomir Rintel]

According to Devicetree maintainers (see Link: below), the Devicetree
binding documents are preferrably licensed (GPL-2.0-only OR
BSD-2-Clause).

Let's check that. The actual check is a bit more relaxed, to allow more
liberal but compatible licensing (e.g. GPL-2.0-or-later OR
BSD-2-Clause).

Link: https://lore.kernel.org/lkml/20200108142132.GA4830@bogus/
Signed-off-by: Lubomir Rintel <lkundrak@xxxxx>

---
Changes since v1:
- Downgrade severity to CHECK when running against existing files [Joe
  Perches]
- Add --fix support [Joe Perches]
Both changes are taken from here: https://lore.kernel.org/lkml/39042657067088e4ca960f630a7d222fc48f947a.camel@xxxxxxxxxxx/
---
 scripts/checkpatch.pl | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index e2976c3fe5ff8..642e897f46e5c 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -3111,6 +3111,17 @@ sub process {
 						WARN("SPDX_LICENSE_TAG",
 						     "'$spdx_license' is not supported in LICENSES/...\n" . $herecurr);
 					}
+					if ($realfile =~ m@^Documentation/devicetree/bindings/@ &&
+					    not $spdx_license =~ /GPL-2\.0.*BSD-2-Clause/) {
+						my $msg_level = \&WARN;
+						$msg_level = \&CHK if ($file);
+						if (&{$msg_level}("SPDX_LICENSE_TAG",
+
+								  "DT binding documents should be licensed (GPL-2.0-only OR BSD-2-Clause)\n" . $herecurr) &&
+						    $fix) {
+							$fixed[$fixlinenr] =~ s/SPDX-License-Identifier: .*/SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)/;
+						}
+					}
 				}
 			}
 		}
-- 
2.25.1