MIPS: Detect the MSA ASE

This patch adds support for probing the MSAP bit within the Config3
register in order to detect the presence of the MSA ASE. Presence of the
ASE will be indicated in /proc/cpuinfo. The value of the MSA
implementation register will be displayed at boot to aid debugging and
verification of a correct setup, as is done for the FPU.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6430/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index e5e6aad..f627739 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -1208,6 +1208,7 @@
 	select CPU_HAS_PREFETCH
 	select CPU_SUPPORTS_32BIT_KERNEL
 	select CPU_SUPPORTS_HIGHMEM
+	select CPU_SUPPORTS_MSA
 	select HAVE_KVM
 	help
 	  Choose this option to build a kernel for release 2 or later of the
@@ -1243,6 +1244,7 @@
 	select CPU_SUPPORTS_64BIT_KERNEL
 	select CPU_SUPPORTS_HIGHMEM
 	select CPU_SUPPORTS_HUGEPAGES
+	select CPU_SUPPORTS_MSA
 	help
 	  Choose this option to build a kernel for release 2 or later of the
 	  MIPS64 architecture.  Many modern embedded systems with a 64-bit
@@ -2081,6 +2083,20 @@
 	  When this option is enabled the kernel will be built using the
 	  microMIPS ISA
 
+config CPU_HAS_MSA
+	bool "Support for the MIPS SIMD Architecture"
+	depends on CPU_SUPPORTS_MSA
+	default y
+	help
+	  MIPS SIMD Architecture (MSA) introduces 128 bit wide vector registers
+	  and a set of SIMD instructions to operate on them. When this option
+	  is enabled the kernel will support detection of the MSA ASE. If you
+	  know that your kernel will only be running on CPUs which do not
+	  support MSA then you may wish to say N here to reduce the size of
+	  your kernel.
+
+	  If unsure, say Y.
+
 config CPU_HAS_WB
 	bool
 
@@ -2146,6 +2162,9 @@
 config SYS_SUPPORTS_MICROMIPS
 	bool
 
+config CPU_SUPPORTS_MSA
+	bool
+
 config ARCH_FLATMEM_ENABLE
 	def_bool y
 	depends on !NUMA && !CPU_LOONGSON2