x86-32: Introduce CONFIG_X86_DEV_DMA_OPS

32-bit x86 systems may need their own DMA operations, so add
a new config option, which is turned on for 64-bit systems. This
patch has no functional effect but it paves the way for supporting
the STA2x11 I/O Hub and possibly other chips.

Signed-off-by: Alessandro Rubini <rubini@gnudd.com>
Link: http://lkml.kernel.org/r/f79fcc1a2e17ef942e1b798b92aac43a80202532.1333560789.git.rubini@gnudd.com
Acked-by: Giancarlo Asnaghi <giancarlo.asnaghi@st.com>
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 1d14cc6..07b412a 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -12,6 +12,7 @@
 
 config X86_64
 	def_bool 64BIT
+	select X86_DEV_DMA_OPS
 
 ### Arch settings
 config X86
@@ -2215,6 +2216,10 @@
 	bool
 	select STOP_MACHINE if SMP
 
+config X86_DEV_DMA_OPS
+	bool
+	depends on X86_64
+
 source "net/Kconfig"
 
 source "drivers/Kconfig"