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Wolfram Sang
c320592f3f
bitops: add generic parity calculation for u8
There are multiple open coded implementations for getting the parity of a byte in the kernel, even using different approaches. Take the pretty efficient version from SPD5118 driver and make it generally available by putting it into the bitops header. As long as there is just one parity calculation helper, the creation of a distinct 'parity.h' header was discarded. Also, the usage of hweight8() for architectures having a popcnt instruction is postponed until a use case within hot paths is desired. The motivation for this patch is the frequent use of odd parity in the I3C specification and to simplify drivers there. Changes compared to the original SPD5118 version are the addition of kernel documentation, switching the return type from bool to int, and renaming the argument of the function. Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Tested-by: Guenter Roeck <linux@roeck-us.net> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be> Acked-by: Yury Norov <yury.norov@gmail.com> Reviewed-by: Kuan-Wei Chiu <visitorckw@gmail.com> Tested-by: Kuan-Wei Chiu <visitorckw@gmail.com> Link: https://lore.kernel.org/r/20250107090204.6593-2-wsa+renesas@sang-engineering.com Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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