sh: Preliminary support for SH-X2 MMU.

This adds some preliminary support for the SH-X2 MMU, used by
newer SH-4A parts (particularly SH7785).

This MMU implements a 'compat' mode with SH-X MMUs and an
'extended' mode for SH-X2 extended features. Extended features
include additional page sizes (8kB, 4MB, 64MB), as well as the
addition of page execute permissions.

The extended mode attributes are placed in a second data array,
which requires us to switch to 64-bit PTEs when in X2 mode.

With the addition of the exec perms, we also overhaul the mmap
prots somewhat, now that it's possible to handle them more
intelligently.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 47 insertions, 2 deletions

diff --git a/arch/sh/mm/Kconfig b/arch/sh/mm/Kconfig
index 27463e26a7b8..88e9663fc9fc 100644
--- a/arch/sh/mm/Kconfig
+++ b/arch/sh/mm/Kconfig
@@ -235,13 +235,22 @@ config MEMORY_SIZE
 
 config 32BIT
         bool "Support 32-bit physical addressing through PMB"
-        depends on CPU_SH4A && MMU
+        depends on CPU_SH4A && MMU && (!X2TLB || BROKEN)
         default y
         help
           If you say Y here, physical addressing will be extended to
           32-bits through the SH-4A PMB. If this is not set, legacy
           29-bit physical addressing will be used.
 
+config X2TLB
+        bool "Enable extended TLB mode"
+        depends on CPU_SUBTYPE_SH7785 && MMU && EXPERIMENTAL
+        help
+          Selecting this option will enable the extended mode of the SH-X2
+          TLB. For legacy SH-X behaviour and interoperability, say N. For
+          all of the fun new features and a willingless to submit bug reports,
+          say Y.
+
 config VSYSCALL
         bool "Support vsyscall page"
         depends on MMU
@@ -256,16 +265,52 @@ config VSYSCALL
           (the default value) say Y.
 
 choice
+        prompt "Kernel page size"
+        default PAGE_SIZE_4KB
+
+config PAGE_SIZE_4KB
+        bool "4kB"
+        help
+          This is the default page size used by all SuperH CPUs.
+
+config PAGE_SIZE_8KB
+        bool "8kB"
+        depends on EXPERIMENTAL && X2TLB
+        help
+          This enables 8kB pages as supported by SH-X2 and later MMUs.
+
+config PAGE_SIZE_64KB
+        bool "64kB"
+        depends on EXPERIMENTAL && CPU_SH4
+        help
+          This enables support for 64kB pages, possible on all SH-4
+          CPUs and later. Highly experimental, not recommended.
+
+endchoice
+
+choice
         prompt "HugeTLB page size"
         depends on HUGETLB_PAGE && CPU_SH4 && MMU
         default HUGETLB_PAGE_SIZE_64K
 
 config HUGETLB_PAGE_SIZE_64K
-        bool "64K"
+        bool "64kB"
+
+config HUGETLB_PAGE_SIZE_256K
+        bool "256kB"
+        depends on X2TLB
 
 config HUGETLB_PAGE_SIZE_1MB
         bool "1MB"
 
+config HUGETLB_PAGE_SIZE_4MB
+        bool "4MB"
+        depends on X2TLB
+
+config HUGETLB_PAGE_SIZE_64MB
+        bool "64MB"
+        depends on X2TLB
+
 endchoice
 
 source "mm/Kconfig"