checkpatch: add --kconfig-prefix

Kconfig allows to customize the CONFIG_ prefix via the $CONFIG_
environment variable.  Out-of-tree projects may therefore use Kconfig with
a different prefix, or they may use a custom configuration tool which does
not use the CONFIG_ prefix at all.  Such projects may still want to adhere
to the Linux kernel coding style and run checkpatch.pl.

One example is OP-TEE [1] which does not use Kconfig but does have
configuration options prefixed with CFG_.  It also mostly follows the
kernel coding style and therefore being able to use checkpatch is quite
valuable.

To make this possible, add the --kconfig-prefix command line option.

[1] https://github.com/OP-TEE/optee_osSigned-off-by: Jerome Forissier <jerome@forissier.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Joe Perches <joe@perches.com>
Link: http://lkml.kernel.org/r/20200818081732.800449-1-jerome@forissier.orgSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -65,6 +65,7 @@ my $allow_c99_comments = 1; # Can be overridden by --ignore C99_COMMENT_TOLERANC
 # git output parsing needs US English output, so first set backtick child process LANGUAGE
 my $git_command ='export LANGUAGE=en_US.UTF-8; git';
 my $tabsize = 8;
+my ${CONFIG_} = "CONFIG_";
 
 sub help {
 	my ($exitcode) = @_;
@@ -127,6 +128,8 @@ Options:
   --typedefsfile             Read additional types from this file
   --color[=WHEN]             Use colors 'always', 'never', or only when output
                              is a terminal ('auto'). Default is 'auto'.
+  --kconfig-prefix=WORD      use WORD as a prefix for Kconfig symbols (default
+                             ${CONFIG_})
   -h, --help, --version      display this help and exit
 
 When FILE is - read standard input.
@@ -235,6 +238,7 @@ GetOptions(
 	'color=s'	=> \$color,
 	'no-color'	=> \$color,	#keep old behaviors of -nocolor
 	'nocolor'	=> \$color,	#keep old behaviors of -nocolor
+	'kconfig-prefix=s'	=> \${CONFIG_},
 	'h|help'	=> \$help,
 	'version'	=> \$help
 ) or help(1);
@@ -6524,16 +6528,16 @@ sub process {
 		}
 
 # check for IS_ENABLED() without CONFIG_<FOO> ($rawline for comments too)
-		if ($rawline =~ /\bIS_ENABLED\s*\(\s*(\w+)\s*\)/ && $1 !~ /^CONFIG_/) {
+		if ($rawline =~ /\bIS_ENABLED\s*\(\s*(\w+)\s*\)/ && $1 !~ /^${CONFIG_}/) {
 			WARN("IS_ENABLED_CONFIG",
-			     "IS_ENABLED($1) is normally used as IS_ENABLED(CONFIG_$1)\n" . $herecurr);
+			     "IS_ENABLED($1) is normally used as IS_ENABLED(${CONFIG_}$1)\n" . $herecurr);
 		}
 
 # check for #if defined CONFIG_<FOO> || defined CONFIG_<FOO>_MODULE
-		if ($line =~ /^\+\s*#\s*if\s+defined(?:\s*\(?\s*|\s+)(CONFIG_[A-Z_]+)\s*\)?\s*\|\|\s*defined(?:\s*\(?\s*|\s+)\1_MODULE\s*\)?\s*$/) {
+		if ($line =~ /^\+\s*#\s*if\s+defined(?:\s*\(?\s*|\s+)(${CONFIG_}[A-Z_]+)\s*\)?\s*\|\|\s*defined(?:\s*\(?\s*|\s+)\1_MODULE\s*\)?\s*$/) {
 			my $config = $1;
 			if (WARN("PREFER_IS_ENABLED",
-				 "Prefer IS_ENABLED(<FOO>) to CONFIG_<FOO> || CONFIG_<FOO>_MODULE\n" . $herecurr) &&
+				 "Prefer IS_ENABLED(<FOO>) to ${CONFIG_}<FOO> || ${CONFIG_}<FOO>_MODULE\n" . $herecurr) &&
 			    $fix) {
 				$fixed[$fixlinenr] = "\+#if IS_ENABLED($config)";
 			}