[PATCH v3 2/6] coccinelle: misc: Add field_modify script

[Luo Jie]

This script finds and suggests conversions of opencoded field
modify patterns with the wrapper FIELD_MODIFY() API defined in
include/linux/bitfield.h for better readability.

Signed-off-by: Luo Jie <quic_luoj at quicinc.com>
---
 scripts/coccinelle/misc/field_modify.cocci | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/scripts/coccinelle/misc/field_modify.cocci b/scripts/coccinelle/misc/field_modify.cocci
new file mode 100644
index 000000000000..9022c1b23291
--- /dev/null
+++ b/scripts/coccinelle/misc/field_modify.cocci
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0-only
+///
+/// Replaced below code with the wrapper FIELD_MODIFY(MASK, &reg, val)
+/// - reg &= ~MASK;
+/// - reg |= FIELD_PREP(MASK, val);
+//
+// Confidence: High
+// Author: Luo Jie <quic_luoj at quicinc.com>
+// Copyright (C) 2025 Qualcomm Innovation Center, Inc.
+// URL: https://coccinelle.gitlabpages.inria.fr/website
+// Keywords: FIELD_PREP, FIELD_MODIFY
+// Options: --include-headers
+
+virtual patch
+
+ at depends on patch@
+identifier reg, val;
+constant mask;
+symbol FIELD_PREP, FIELD_MODIFY;
+@@
+
+- reg &= ~mask;
+- reg |= FIELD_PREP(mask, val);
++ FIELD_MODIFY(mask, &reg, val);

-- 
2.34.1