[PATCH] LICENSES: Explicitly allow SPDX-FileCopyrightText

[Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>]

Sources already have SPDX-FileCopyrightText (~40 instances) and more
appear on the mailing list, so document that it is allowed.  On the
other hand SPDX defines several other tags like SPDX-FileType, so add
checkpatch rule to narrow desired tags only to two of them - license and
copyright.  That way no new tags would sneak in to the kernel unnoticed.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>

---

Other way would be to remove SPDX-FileCopyrightText from existing files
and disallow this, but one way or another we should be explicit about
it.  Otherwise people will be sending more of these and each maintainer
would need to make their own call.
---
 Documentation/process/license-rules.rst | 2 ++
 scripts/checkpatch.pl                   | 9 +++++++++
 2 files changed, 11 insertions(+)

diff --git a/Documentation/process/license-rules.rst b/Documentation/process/license-rules.rst
index 59a7832df7d0..8d7c0214f283 100644
--- a/Documentation/process/license-rules.rst
+++ b/Documentation/process/license-rules.rst
@@ -66,6 +66,8 @@ License identifier syntax
    '#!PATH_TO_INTERPRETER' in the first line.  For those scripts the SPDX
    identifier goes into the second line.
 
+   Identifier line can be followed by another one with SPDX-FileCopyrightText.
+
 |
 
 2. Style:
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 362a8d1cd327..98261ee97e2b 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -3844,6 +3844,15 @@ sub process {
 			     "Misplaced SPDX-License-Identifier tag - use line $checklicenseline instead\n" . $herecurr);
 		}
 
+# check for unused SPDX file tags
+		if ($rawline =~ /\bSPDX-.*:/ &&
+		    $rawline !~ /\bSPDX-License-Identifier:/ &&
+		    $rawline !~ /\bSPDX-FileCopyrightText:/) {
+			WARN("SPDX_LICENSE_TAG",
+			     "Unsupported SPDX tag\n" . $herecurr);
+		}
+
+
 # line length limit (with some exclusions)
 #
 # There are a few types of lines that may extend beyond $max_line_length:
-- 
2.51.0