nios2: Add new architecture

This commit adds very basic support to build for the Nios II
architecture. Toolchain support is still missing and instead
we need to use an external custom toolchain.

Notice that this architecture had been previously removed in
Buildroot 2010.05-rc1 release (as explained in the CHANGES file)
and this commit adds it back.

Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

arch/Config.in

@@ -124,6 +124,13 @@ config BR2_mips64el
 	  http://www.mips.com/
 	  http://en.wikipedia.org/wiki/MIPS_Technologies
 
+config BR2_nios2
+	bool "Nios II"
+	help
+	  Nios II is a soft core processor from Altera Corporation.
+	  http://www.altera.com/
+	  http://en.wikipedia.org/wiki/Nios_II
+
 config BR2_powerpc
 	bool "PowerPC"
 	help
@@ -305,6 +312,10 @@ if BR2_mips || BR2_mips64 || BR2_mipsel || BR2_mips64el
 source "arch/Config.in.mips"
 endif
 
+if BR2_nios2
+source "arch/Config.in.nios2"
+endif
+
 if BR2_powerpc
 source "arch/Config.in.powerpc"
 endif

arch/Config.in.nios2

@@ -0,0 +1,5 @@
+config BR2_ARCH
+	default "nios2"
+
+config BR2_ENDIAN
+	default "LITTLE"

toolchain/Config.in

@@ -25,7 +25,7 @@ choice
 
 config BR2_TOOLCHAIN_BUILDROOT
 	bool "Buildroot toolchain"
-	depends on !BR2_microblaze && !BR2_aarch64
+	depends on !BR2_microblaze && !BR2_aarch64 && !BR2_nios2
 	select BR2_TOOLCHAIN_HAS_SHADOW_PASSWORDS
 
 config BR2_TOOLCHAIN_EXTERNAL
@@ -38,7 +38,8 @@ config BR2_TOOLCHAIN_EXTERNAL
 config BR2_TOOLCHAIN_CTNG
 	bool "Crosstool-NG toolchain"
 	depends on BR2_DEPRECATED
-	depends on !BR2_microblaze && !BR2_aarch64 && !BR2_xtensa && !BR2_arc
+	depends on !BR2_microblaze && !BR2_aarch64 && !BR2_xtensa && \
+		   !BR2_arc && !BR2_nios2
 	select BR2_TOOLCHAIN_HAS_SHADOW_PASSWORDS
 	help
 	  Say 'y' if you want to generate the toolchain with crosstool-NG