linux-kernel - [PATCH 3/9] bitmap: Use FIELD_PREP() in expansion of FIELD_PREP

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Message-Id: <20251208224250.536159-4-david.laight.linux@gmail.com>
Date: Mon,  8 Dec 2025 22:42:44 +0000
From: david.laight.linux@...il.com
To: Yury Norov <yury.norov@...il.com>,
	Rasmus Villemoes <linux@...musvillemoes.dk>,
	linux-kernel@...r.kernel.org,
	linux-usb@...r.kernel.org,
	Geert Uytterhoeven <geert+renesas@...der.be>
Cc: David Laight <david.laight.linux@...il.com>
Subject: [PATCH 3/9] bitmap: Use FIELD_PREP() in expansion of FIELD_PREP_WM16()

From: David Laight <david.laight.linux@...il.com>

Instead of directly expanding __BF_FIELD_CHECK() (which really ought
not be used outside bitfield) and open-coding the generation of the
masked value, just call FIELD_PREP() and add an extra check for
the mask being at most 16 bits.

Signed-off-by: David Laight <david.laight.linux@...il.com>
---
 include/linux/hw_bitfield.h | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/include/linux/hw_bitfield.h b/include/linux/hw_bitfield.h
index df202e167ce4..d7f21b60449b 100644
--- a/include/linux/hw_bitfield.h
+++ b/include/linux/hw_bitfield.h
@@ -23,15 +23,14 @@
  * register, a bit in the lower half is only updated if the corresponding bit
  * in the upper half is high.
  */
-#define FIELD_PREP_WM16(_mask, _val)					     \
-	({								     \
-		typeof(_val) __val = _val;				     \
-		typeof(_mask) __mask = _mask;				     \
-		__BF_FIELD_CHECK(__mask, ((u16)0U), __val,		     \
-				 "HWORD_UPDATE: ");			     \
-		(((typeof(__mask))(__val) << __bf_shf(__mask)) & (__mask)) | \
-		((__mask) << 16);					     \
-	})
+#define FIELD_PREP_WM16(mask, val)				\
+({								\
+	__auto_type _mask = mask;				\
+	u32 _val = FIELD_PREP(_mask, val);			\
+	BUILD_BUG_ON_MSG(_mask > 0xffffu,			\
+			 "FIELD_PREP_WM16: mask too large");	\
+	_val | (_mask << 16);					\
+})
 
 /**
  * FIELD_PREP_WM16_CONST() - prepare a constant bitfield element with a mask in
-- 
2.39.5