powerpc: Use CONFIG_ARCH_HAS_FAST_MULTIPLIER

I ran some tests to compare hash_64 using shifts and multiplies.
The results:

POWER6:	~2x slower
POWER7: ~2x faster
POWER8: ~2x faster

Now we have a proper config option, select
CONFIG_ARCH_HAS_FAST_MULTIPLIER on POWER7 and POWER8.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 26703be24cf9..35ae7ec392ec 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -116,10 +116,12 @@ config POWER6_CPU
 config POWER7_CPU
         bool "POWER7"
         depends on PPC_BOOK3S_64
+        select ARCH_HAS_FAST_MULTIPLIER
 
 config POWER8_CPU
         bool "POWER8"
         depends on PPC_BOOK3S_64
+        select ARCH_HAS_FAST_MULTIPLIER
 
 config E5500_CPU
         bool "Freescale e5500"