[MIPS] Add basic SMARTMIPS ASE support

This patch adds trivial support for SMARTMIPS extension. This extension
is currently implemented by 4KS[CD] CPUs.

Basically it saves/restores ACX register, which is part of the SMARTMIPS
ASE, when needed. This patch does *not* add any support for Smartmips MMU
features.

Futhermore this patch does not add explicit support for 4KS[CD] CPUs since
they are respectively mips32 and mips32r2 compliant.  So with the current
processor configuration, a platform that has such CPUs needs to select
both configs:

	CPU_HAS_SMARTMIPS
	SYS_HAS_CPU_MIPS32_R[12]

This is due to the processor configuration which is mixing up all the
architecture variants and the processor types.

The drawback of this, is that we currently pass '-march=mips32' option to
gcc when building a kernel instead of '-march=4ksc' for 4KSC case. This
can lead to a kernel image a little bit bigger than required.

Signed-off-by: Franck Bui-Huu <fbuihuu@gmail.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/mips/Makefile b/arch/mips/Makefile
index c68b5d3e5d18..92bca6ad6ab1 100644
--- a/arch/mips/Makefile
+++ b/arch/mips/Makefile
@@ -103,6 +103,8 @@ predef-le += -DMIPSEL -D_MIPSEL -D__MIPSEL -D__MIPSEL__
 cflags-$(CONFIG_CPU_BIG_ENDIAN)         += $(shell $(CC) -dumpmachine |grep -q 'mips.*el-.*' && echo -EB $(undef-all) $(predef-be))
 cflags-$(CONFIG_CPU_LITTLE_ENDIAN)      += $(shell $(CC) -dumpmachine |grep -q 'mips.*el-.*' || echo -EL $(undef-all) $(predef-le))
 
+cflags-$(CONFIG_CPU_HAS_SMARTMIPS)      += $(call cc-option,-msmartmips)
+
 cflags-$(CONFIG_SB1XXX_CORELIS) += $(call cc-option,-mno-sched-prolog) \
                                    -fno-omit-frame-pointer