MIPS: Add support for XPA.

Add support for extended physical addressing (XPA) so that
32-bit platforms can access equal to or greater than 40 bits
of physical addresses.

NOTE:
      1) XPA and EVA are not the same and cannot be used
         simultaneously.
      2) If you configure your kernel for XPA, the PTEs
         and all address sizes become 64-bit.
      3) Your platform MUST have working HIGHMEM support.

Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9355/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 35 insertions, 0 deletions

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index c7a16904cd03..69a3b0fab926 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -377,6 +377,7 @@ config MIPS_MALTA
         select SYS_HAS_CPU_MIPS32_R1
         select SYS_HAS_CPU_MIPS32_R2
         select SYS_HAS_CPU_MIPS32_R3_5
+        select SYS_HAS_CPU_MIPS32_R5
         select SYS_HAS_CPU_MIPS32_R6
         select SYS_HAS_CPU_MIPS64_R1
         select SYS_HAS_CPU_MIPS64_R2
@@ -386,6 +387,7 @@ config MIPS_MALTA
         select SYS_SUPPORTS_32BIT_KERNEL
         select SYS_SUPPORTS_64BIT_KERNEL
         select SYS_SUPPORTS_BIG_ENDIAN
+        select SYS_SUPPORTS_HIGHMEM
         select SYS_SUPPORTS_LITTLE_ENDIAN
         select SYS_SUPPORTS_MICROMIPS
         select SYS_SUPPORTS_MIPS_CMP
@@ -1596,6 +1598,33 @@ config CPU_MIPS32_3_5_EVA
           One of its primary benefits is an increase in the maximum size
           of lowmem (up to 3GB). If unsure, say 'N' here.
 
+config CPU_MIPS32_R5_FEATURES
+        bool "MIPS32 Release 5 Features"
+        depends on SYS_HAS_CPU_MIPS32_R5
+        depends on CPU_MIPS32_R2
+        help
+          Choose this option to build a kernel for release 2 or later of the
+          MIPS32 architecture including features from release 5 such as
+          support for Extended Physical Addressing (XPA).
+
+config CPU_MIPS32_R5_XPA
+        bool "Extended Physical Addressing (XPA)"
+        depends on CPU_MIPS32_R5_FEATURES
+        depends on !EVA
+        depends on !PAGE_SIZE_4KB
+        depends on SYS_SUPPORTS_HIGHMEM
+        select XPA
+        select HIGHMEM
+        select ARCH_PHYS_ADDR_T_64BIT
+        default n
+        help
+          Choose this option if you want to enable the Extended Physical
+          Addressing (XPA) on your MIPS32 core (such as P5600 series). The
+          benefit is to increase physical addressing equal to or greater
+          than 40 bits. Note that this has the side effect of turning on
+          64-bit addressing which in turn makes the PTEs 64-bit in size.
+          If unsure, say 'N' here.
+
 if CPU_LOONGSON2F
 config CPU_NOP_WORKAROUNDS
         bool
@@ -1699,6 +1728,9 @@ config SYS_HAS_CPU_MIPS32_R2
 config SYS_HAS_CPU_MIPS32_R3_5
         bool
 
+config SYS_HAS_CPU_MIPS32_R5
+        bool
+
 config SYS_HAS_CPU_MIPS32_R6
         bool
 
@@ -1836,6 +1868,9 @@ config CPU_MIPSR6
 config EVA
         bool
 
+config XPA
+        bool
+
 config SYS_SUPPORTS_32BIT_KERNEL
         bool
 config SYS_SUPPORTS_64BIT_KERNEL