[PATCH RFC 1/2] bitops: introduce BITS_MASK macro

[srinivas.kandagatla]

From: Srinivas Kandagatla <srinivas.kandagatla@xxxxxx>

This patch introduces BITS_MASK macro which creates a mask for a given
lsb and msb bit locations. The usage of masks spread over mutiple bits
is becoming very common for example with regmap_update_bits kind of
apis. Having a common macro for this makes much sense and is clean and
readable way to encode the mask rather than having an hex number for a
mask.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxx>
---
 include/linux/bitops.h |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index a3b6b82..3ddce97 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -5,6 +5,7 @@
 #ifdef	__KERNEL__
 #define BIT(nr)			(1UL << (nr))
 #define BIT_MASK(nr)		(1UL << ((nr) % BITS_PER_LONG))
+#define BITS_MASK(lsb, msb)	((BIT(msb - lsb + 1) - 1) << lsb)
 #define BIT_WORD(nr)		((nr) / BITS_PER_LONG)
 #define BITS_PER_BYTE		8
 #define BITS_TO_LONGS(nr)	DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
-- 
1.7.6.5

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