Re: [PATCH v6 02/17] powerpc/vas: Move GET_FIELD/SET_FIELD to vas.h
From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2017-08-14 07:26:09
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lkml
Sukadev Bhattiprolu [off-list ref] writes:
Move the GET_FIELD and SET_FIELD macros to vas.h as VAS and other users of VAS, including NX-842 can use those macros. There is a lot of related code between the VAS/NX kernel drivers and skiboot. For consistency switch the order of parameters in SET_FIELD to match the order in skiboot. Signed-off-by: Sukadev Bhattiprolu <redacted> Reviewed-by: Dan Streetman <redacted>
quoted hunk ↗ jump to hunk
diff --git a/arch/powerpc/include/uapi/asm/vas.h b/arch/powerpc/include/uapi/asm/vas.h index ddfe046..21249f5 100644 --- a/arch/powerpc/include/uapi/asm/vas.h +++ b/arch/powerpc/include/uapi/asm/vas.h@@ -22,4 +22,12 @@ #define VAS_THRESH_FIFO_GT_QTR_FULL 2 #define VAS_THRESH_FIFO_GT_EIGHTH_FULL 3 +/* + * Get/Set bit fields + */ +#define GET_FIELD(m, v) (((v) & (m)) >> MASK_LSH(m)) +#define MASK_LSH(m) (__builtin_ffsl(m) - 1) +#define SET_FIELD(m, v, val) \ + (((v) & ~(m)) | ((((typeof(v))(val)) << MASK_LSH(m)) & (m)))
This has no business being in a uapi header for VAS. Put it in asm/vas.h if you must. Personally I really dislike these sort of macros because they completely obscure what the final value should end up being, and it's the final value you'll see when you're debugging it.
+ ccw = SET_FIELD(CCW_CT, ccw, nx842_ct); + ccw = SET_FIELD(CCW_CI_842, ccw, 0); /* use 0 for hw auto-selection */ + ccw = SET_FIELD(CCW_FC_842, ccw, fc);
eg. that could also be written:
ccw = (nx842_ct << 16) | (fc & 7);
cheers