powerpc: add support for csum_add()
authorLEROY Christophe <christophe.leroy@c-s.fr>
Tue, 19 May 2015 15:18:57 +0000 (17:18 +0200)
committerScott Wood <scottwood@freescale.com>
Sat, 8 Aug 2015 03:59:19 +0000 (22:59 -0500)
commit501c8de7b061d2dc0c21a0a79fee3eddf30af8dd
treee06b9dcf4206de9f6a00cce28fca21929a6373ec
parent92c985f1d76c228abe202cb3004f03c9b45860d1
powerpc: add support for csum_add()

The C version of csum_add() as defined in include/net/checksum.h gives
the following assembly in ppc32:
       0:       7c 04 1a 14     add     r0,r4,r3
       4:       7c 64 00 10     subfc   r3,r4,r0
       8:       7c 63 19 10     subfe   r3,r3,r3
       c:       7c 63 00 50     subf    r3,r3,r0
and the following in ppc64:
   0xc000000000001af8 <+0>: add     r3,r3,r4
   0xc000000000001afc <+4>: cmplw   cr7,r3,r4
   0xc000000000001b00 <+8>: mfcr    r4
   0xc000000000001b04 <+12>: rlwinm  r4,r4,29,31,31
   0xc000000000001b08 <+16>: add     r3,r4,r3
   0xc000000000001b0c <+20>: clrldi  r3,r3,32
   0xc000000000001b10 <+24>: blr

include/net/checksum.h also offers the possibility to define an arch
specific function.  This patch provides a specific csum_add() inline
function.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Scott Wood <scottwood@freescale.com>
arch/powerpc/include/asm/checksum.h