mips: Add MIPS Release 5 support

There are five MIPS32/64 architecture releases currently available:
from 1 to 6 except fourth one, which was intentionally skipped.
Three of them can be called as major: 1st, 2nd and 6th, that not only
have some system level alterations, but also introduced significant
core/ISA level updates. The rest of the MIPS architecture releases are
minor.

Even though they don't have as much ISA/system/core level changes
as the major ones with respect to the previous releases, they still
provide a set of updates (I'd say they were intended to be the
intermediate releases before a major one) that might be useful for the
kernel and user-level code, when activated by the kernel or compiler.
In particular the following features were introduced or ended up being
available at/after MIPS32/64 Release 5 architecture:
+ the last release of the misaligned memory access instructions,
+ virtualisation - VZ ASE - is optional component of the arch,
+ SIMD - MSA ASE - is optional component of the arch,
+ DSP ASE is optional component of the arch,
+ CP0.Status.FR=1 for CP1.FIR.F64=1 (pure 64-bit FPU general registers)
  must be available if FPU is implemented,
+ CP1.FIR.Has2008 support is required so CP1.FCSR.{ABS2008,NAN2008} bits
  are available.
+ UFR/UNFR aliases to access CP0.Status.FR from user-space by means of
  ctc1/cfc1 instructions (enabled by CP0.Config5.UFR),
+ CP0.COnfig5.LLB=1 and eretnc instruction are implemented to without
  accidentally clearing LL-bit when returning from an interrupt,
  exception, or error trap,
+ XPA feature together with extended versions of CPx registers is
  introduced, which needs to have mfhc0/mthc0 instructions available.

So due to these changes GNU GCC provides an extended instructions set
support for MIPS32/64 Release 5 by default like eretnc/mfhc0/mthc0. Even
though the architecture alteration isn't that big, it still worth to be
taken into account by the kernel software. Finally we can't deny that
some optimization/limitations might be found in future and implemented
on some level in kernel or compiler. In this case having even
intermediate MIPS architecture releases support would be more than
useful.

So the most of the changes provided by this commit can be split into
either compile- or runtime configs related. The compile-time related
changes are caused by adding the new CONFIG_CPU_MIPS32_R5/CONFIG_CPU_MIPSR5
configs and concern the code activating MIPSR2 or MIPSR6 already
implemented features (like eretnc/LLbit, mthc0/mfhc0). In addition
CPU_HAS_MSA can be now freely enabled for MIPS32/64 release 5 based
platforms as this is done for CPU_MIPS32_R6 CPUs. The runtime changes
concerns the features which are handled with respect to the MIPS ISA
revision detected at run-time by means of CP0.Config.{AT,AR} bits. Alas
these fields can be used to detect either r1 or r2 or r6 releases.
But since we know which CPUs in fact support the R5 arch, we can manually
set MIPS_CPU_ISA_M32R5/MIPS_CPU_ISA_M64R5 bit of c->isa_level and then
use cpu_has_mips32r5/cpu_has_mips64r5 where it's appropriate.

Since XPA/EVA provide too complex alterationss and to have them used with
MIPS32 Release 2 charged kernels (for compatibility with current platform
configs) they are left to be setup as a separate kernel configs.

Co-developed-by: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
Signed-off-by: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Paul Burton <paulburton@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: devicetree@vger.kernel.org
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

1 files changed, 51 insertions, 5 deletions

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index b2ff77f8366f..9dc173ff7293 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -1516,6 +1516,21 @@ config CPU_MIPS32_R2
 	  specific type of processor in your system, choose those that one
 	  otherwise CPU_MIPS32_R1 is a safe bet for any MIPS32 system.
 
+config CPU_MIPS32_R5
+	bool "MIPS32 Release 5"
+	depends on SYS_HAS_CPU_MIPS32_R5
+	select CPU_HAS_PREFETCH
+	select CPU_SUPPORTS_32BIT_KERNEL
+	select CPU_SUPPORTS_HIGHMEM
+	select CPU_SUPPORTS_MSA
+	select HAVE_KVM
+	select MIPS_O32_FP64_SUPPORT
+	help
+	  Choose this option to build a kernel for release 5 or later of the
+	  MIPS32 architecture.  New MIPS processors, starting with the Warrior
+	  family, are based on a MIPS32r5 processor. If you own an older
+	  processor, you probably need to select MIPS32r1 or MIPS32r2 instead.
+
 config CPU_MIPS32_R6
 	bool "MIPS32 Release 6"
 	depends on SYS_HAS_CPU_MIPS32_R6
@@ -1568,6 +1583,23 @@ config CPU_MIPS64_R2
 	  specific type of processor in your system, choose those that one
 	  otherwise CPU_MIPS64_R1 is a safe bet for any MIPS64 system.
 
+config CPU_MIPS64_R5
+	bool "MIPS64 Release 5"
+	depends on SYS_HAS_CPU_MIPS64_R5
+	select CPU_HAS_PREFETCH
+	select CPU_SUPPORTS_32BIT_KERNEL
+	select CPU_SUPPORTS_64BIT_KERNEL
+	select CPU_SUPPORTS_HIGHMEM
+	select CPU_SUPPORTS_HUGEPAGES
+	select CPU_SUPPORTS_MSA
+	select MIPS_O32_FP64_SUPPORT if 32BIT || MIPS32_O32
+	select HAVE_KVM
+	help
+	  Choose this option to build a kernel for release 5 or later of the
+	  MIPS64 architecture.  This is a intermediate MIPS architecture
+	  release partly implementing release 6 features. Though there is no
+	  any hardware known to be based on this release.
+
 config CPU_MIPS64_R6
 	bool "MIPS64 Release 6"
 	depends on SYS_HAS_CPU_MIPS64_R6
@@ -1762,7 +1794,7 @@ endchoice
 config CPU_MIPS32_3_5_FEATURES
 	bool "MIPS32 Release 3.5 Features"
 	depends on SYS_HAS_CPU_MIPS32_R3_5
-	depends on CPU_MIPS32_R2 || CPU_MIPS32_R6
+	depends on CPU_MIPS32_R2 || CPU_MIPS32_R5 || CPU_MIPS32_R6
 	help
 	  Choose this option to build a kernel for release 2 or later of the
 	  MIPS32 architecture including features from the 3.5 release such as
@@ -1782,7 +1814,7 @@ config CPU_MIPS32_3_5_EVA
 config CPU_MIPS32_R5_FEATURES
 	bool "MIPS32 Release 5 Features"
 	depends on SYS_HAS_CPU_MIPS32_R5
-	depends on CPU_MIPS32_R2
+	depends on CPU_MIPS32_R2 || CPU_MIPS32_R5
 	help
 	  Choose this option to build a kernel for release 2 or later of the
 	  MIPS32 architecture including features from release 5 such as
@@ -2020,11 +2052,13 @@ endmenu
 #
 config CPU_MIPS32
 	bool
-	default y if CPU_MIPS32_R1 || CPU_MIPS32_R2 || CPU_MIPS32_R6
+	default y if CPU_MIPS32_R1 || CPU_MIPS32_R2 || CPU_MIPS32_R5 || \
+		     CPU_MIPS32_R6
 
 config CPU_MIPS64
 	bool
-	default y if CPU_MIPS64_R1 || CPU_MIPS64_R2 || CPU_MIPS64_R6
+	default y if CPU_MIPS64_R1 || CPU_MIPS64_R2 || CPU_MIPS64_R5 || \
+		     CPU_MIPS64_R6
 
 #
 # These indicate the revision of the architecture
@@ -2040,6 +2074,13 @@ config CPU_MIPSR2
 	select CPU_HAS_DIEI if !CPU_DIEI_BROKEN
 	select MIPS_SPRAM
 
+config CPU_MIPSR5
+	bool
+	default y if CPU_MIPS32_R5 || CPU_MIPS64_R5
+	select CPU_HAS_RIXI
+	select CPU_HAS_DIEI if !CPU_DIEI_BROKEN
+	select MIPS_SPRAM
+
 config CPU_MIPSR6
 	bool
 	default y if CPU_MIPS32_R6 || CPU_MIPS64_R6
@@ -2054,6 +2095,7 @@ config TARGET_ISA_REV
 	int
 	default 1 if CPU_MIPSR1
 	default 2 if CPU_MIPSR2
+	default 5 if CPU_MIPSR5
 	default 6 if CPU_MIPSR6
 	default 0
 	help
@@ -2643,7 +2685,11 @@ config NEED_PER_CPU_EMBED_FIRST_CHUNK
 
 config RELOCATABLE
 	bool "Relocatable kernel"
-	depends on SYS_SUPPORTS_RELOCATABLE && (CPU_MIPS32_R2 || CPU_MIPS64_R2 || CPU_MIPS32_R6 || CPU_MIPS64_R6 || CAVIUM_OCTEON_SOC)
+	depends on SYS_SUPPORTS_RELOCATABLE
+	depends on CPU_MIPS32_R2 || CPU_MIPS64_R2 || \
+		   CPU_MIPS32_R5 || CPU_MIPS64_R5 || \
+		   CPU_MIPS32_R6 || CPU_MIPS64_R6 || \
+		   CAVIUM_OCTEON_SOC
 	help
 	  This builds a kernel image that retains relocation information
 	  so it can be loaded someplace besides the default 1MB.