sh: Add kmap_coherent()/kunmap_coherent() interface for SH-4.

This wires up kmap_coherent() and kunmap_coherent() on SH-4, and
moves away from the p3map_mutex and reserved P3 space, opting to
use fixmaps for colouring instead.

The copy_user_page()/clear_user_page() implementations are moved
to this, which fixes the nasty blowups with spinlock debugging
as a result of having some of these calls nested under the page
table lock.

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

include/asm-sh/fixmap.h

@@ -46,6 +46,9 @@
  * fix-mapped?
  */
 enum fixed_addresses {
+#define FIX_N_COLOURS 16
+	FIX_CMAP_BEGIN,
+	FIX_CMAP_END = FIX_CMAP_BEGIN + FIX_N_COLOURS,
 #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,
@@ -53,8 +56,8 @@ enum fixed_addresses {
 	__end_of_fixed_addresses
 };
 
-extern void __set_fixmap (enum fixed_addresses idx,
-					unsigned long phys, pgprot_t flags);
+extern void __set_fixmap(enum fixed_addresses idx,
+			 unsigned long phys, pgprot_t flags);
 
 #define set_fixmap(idx, phys) \
 		__set_fixmap(idx, phys, PAGE_KERNEL)
@@ -106,5 +109,4 @@ static inline unsigned long virt_to_fix(const unsigned long vaddr)
 	BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
 	return __virt_to_fix(vaddr);
 }
-
 #endif