Merge branch 'topic/hwdep-cleanup' into topic/hdsp

[linux-2.6-omap-h63xx.git] / arch / x86 / include / asm / pgtable.h

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 83e69f4a37f03bafb39869169d6286210c7c95df..06bbcbd66e9c508285020b65c6d411afd2bfe59b 100644 (file)
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -341,6 +341,25 @@ static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
 
 #define canon_pgprot(p) __pgprot(pgprot_val(p) & __supported_pte_mask)
 
+static inline int is_new_memtype_allowed(unsigned long flags,
+                                               unsigned long new_flags)
+{
+       /*
+        * Certain new memtypes are not allowed with certain
+        * requested memtype:
+        * - request is uncached, return cannot be write-back
+        * - request is write-combine, return cannot be write-back
+        */
+       if ((flags == _PAGE_CACHE_UC_MINUS &&
+            new_flags == _PAGE_CACHE_WB) ||
+           (flags == _PAGE_CACHE_WC &&
+            new_flags == _PAGE_CACHE_WB)) {
+               return 0;
+       }
+
+       return 1;
+}
+
 #ifndef __ASSEMBLY__
 /* Indicate that x86 has its own track and untrack pfn vma functions */
 #define __HAVE_PFNMAP_TRACKING