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bits: introduce fixed-type BIT_U*()

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Implement fixed-type BIT_U*() to help drivers add stricter checks,
like it was done for GENMASK_U*().

Signed-off-by: Lucas De Marchi <[email protected]>
Acked-by: Jani Nikula <[email protected]>
Co-developed-by: Vincent Mailhol <[email protected]>
Signed-off-by: Vincent Mailhol <[email protected]>
Reviewed-by: Andy Shevchenko <[email protected]>
Signed-off-by: Yury Norov <[email protected]>
This commit is contained in:
Lucas De Marchi authored and Yury Norov committed 2025-04-29 15:58:38 -04:00
1 parent 19408200c0
commit 5b572e8a9f
1 file changed
+19 -1
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include/linux/bits.h
+19 -1
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@@ -24,7 +24,7 @@
/*
* Missing asm support
*
* GENMASK_U*() depend on BITS_PER_TYPE() which relies on sizeof(),
* GENMASK_U*() and BIT_U*() depend on BITS_PER_TYPE() which relies on sizeof(),
* something not available in asm. Nevertheless, fixed width integers is a C
* concept. Assembly code can rely on the long and long long versions instead.
*/
@@ -55,6 +55,24 @@
#define GENMASK_U32(h, l) GENMASK_TYPE(u32, h, l)
#define GENMASK_U64(h, l) GENMASK_TYPE(u64, h, l)
/*
* Fixed-type variants of BIT(), with additional checks like GENMASK_TYPE(). The
* following examples generate compiler warnings due to -Wshift-count-overflow:
*
* - BIT_U8(8)
* - BIT_U32(-1)
* - BIT_U32(40)
*/
#define BIT_INPUT_CHECK(type, nr) \
BUILD_BUG_ON_ZERO(const_true((nr) >= BITS_PER_TYPE(type)))
#define BIT_TYPE(type, nr) ((type)(BIT_INPUT_CHECK(type, nr) + BIT_ULL(nr)))
#define BIT_U8(nr) BIT_TYPE(u8, nr)
#define BIT_U16(nr) BIT_TYPE(u16, nr)
#define BIT_U32(nr) BIT_TYPE(u32, nr)
#define BIT_U64(nr) BIT_TYPE(u64, nr)
#else /* defined(__ASSEMBLY__) */
/*