asm-generic: add NEED_SG_DMA_LENGTH to define sg_dma_len()

There are only two ways to define sg_dma_len(); use sg->dma_length or
sg->length.  This patch introduces NEED_SG_DMA_LENGTH that enables
architectures to choose sg->dma_length or sg->length.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index e0c619c55b4e..5bdc143b1228 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -109,6 +109,9 @@ config SBUS
 config NEED_DMA_MAP_STATE
        def_bool (X86_64 || DMAR || DMA_API_DEBUG)
 
+config NEED_SG_DMA_LENGTH
+        def_bool X86_64
+
 config GENERIC_ISA_DMA
         def_bool y