sh: Preparation for uncached jumps through PMB.

Presently most of the 29-bit physical parts do P1/P2 segmentation
with a 1:1 cached/uncached mapping, jumping between the two to
control the caching behaviour. This provides the basic infrastructure
to maintain this behaviour on 32-bit physical parts that don't map
P1/P2 at all, using a shiny new linker section and corresponding
fixmap entry.

Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

5 files changed, 27 insertions, 20 deletions

diff --git a/include/asm-sh/fixmap.h b/include/asm-sh/fixmap.h
index 09463cd9bbb9..721fcc4d5e98 100644
--- a/include/asm-sh/fixmap.h
+++ b/include/asm-sh/fixmap.h
@@ -49,6 +49,7 @@ enum fixed_addresses {
 #define FIX_N_COLOURS 16
         FIX_CMAP_BEGIN,
         FIX_CMAP_END = FIX_CMAP_BEGIN + FIX_N_COLOURS,
+        FIX_UNCACHED,
 #ifdef CONFIG_HIGHMEM
         FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */
         FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
diff --git a/include/asm-sh/sections.h b/include/asm-sh/sections.h
index bd9cbc967c2a..8f8f4ad400df 100644
--- a/include/asm-sh/sections.h
+++ b/include/asm-sh/sections.h
@@ -4,6 +4,7 @@
 #include <asm-generic/sections.h>
 
 extern long __machvec_start, __machvec_end;
+extern char __uncached_start, __uncached_end;
 extern char _ebss[];
 
 #endif /* __ASM_SH_SECTIONS_H */
diff --git a/include/asm-sh/system.h b/include/asm-sh/system.h
index 969f3d4afe2a..9bda8d063ecf 100644
--- a/include/asm-sh/system.h
+++ b/include/asm-sh/system.h
@@ -144,6 +144,8 @@ extern unsigned int instruction_size(unsigned int insn);
 #define instruction_size(insn)  (4)
 #endif
 
+extern unsigned long cached_to_uncached;
+
 /* XXX
  * disable hlt during certain critical i/o operations
  */
diff --git a/include/asm-sh/system_32.h b/include/asm-sh/system_32.h
index ad37e8d5f31e..e918bacd5ecf 100644
--- a/include/asm-sh/system_32.h
+++ b/include/asm-sh/system_32.h
@@ -58,29 +58,31 @@ do {								\
         last = __last;                                          \
 } while (0)
 
+#define __uses_jump_to_uncached __attribute__ ((__section__ (".uncached.text")))
+
 /*
- * Jump to P2 area.
- * When handling TLB or caches, we need to do it from P2 area.
+ * Jump to uncached area.
+ * When handling TLB or caches, we need to do it from an uncached area.
  */
-#define jump_to_P2()                    \
-do {                                    \
-        unsigned long __dummy;          \
-        __asm__ __volatile__(           \
-                "mov.l  1f, %0\n\t"     \
-                "or     %1, %0\n\t"     \
-                "jmp    @%0\n\t"        \
-                " nop\n\t"              \
-                ".balign 4\n"           \
-                "1:     .long 2f\n"     \
-                "2:"                    \
-                : "=&r" (__dummy)       \
-                : "r" (0x20000000));    \
+#define jump_to_uncached()                      \
+do {                                            \
+        unsigned long __dummy;                  \
+                                                \
+        __asm__ __volatile__(                   \
+                "mova   1f, %0\n\t"             \
+                "add    %1, %0\n\t"             \
+                "jmp    @%0\n\t"                \
+                " nop\n\t"                      \
+                ".balign 4\n"                   \
+                "1:"                            \
+                : "=&z" (__dummy)               \
+                : "r" (cached_to_uncached));    \
 } while (0)
 
 /*
- * Back to P1 area.
+ * Back to cached area.
  */
-#define back_to_P1()                                    \
+#define back_to_cached()                                \
 do {                                                    \
         unsigned long __dummy;                          \
         ctrl_barrier();                                 \
diff --git a/include/asm-sh/system_64.h b/include/asm-sh/system_64.h
index 0e466e991f7d..943acf5ea07c 100644
--- a/include/asm-sh/system_64.h
+++ b/include/asm-sh/system_64.h
@@ -32,8 +32,9 @@ do {								\
                               &next->thread);                   \
 } while (0)
 
-/* No segmentation.. */
-#define jump_to_P2()    do { } while (0)
-#define back_to_P1()    do { } while (0)
+#define __uses_jump_to_uncached
+
+#define jump_to_uncached()      do { } while (0)
+#define back_to_cached()        do { } while (0)
 
 #endif /* __ASM_SH_SYSTEM_64_H */