x86: PAT add ioremap_wc() interface
Introduce ioremap_wc for wc remap.
(generic wrapper is in a later patch)
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 0cdb7f1..51cd395 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -97,6 +97,9 @@
default:
err = _set_memory_uc(vaddr, nrpages);
break;
+ case _PAGE_CACHE_WC:
+ err = _set_memory_wc(vaddr, nrpages);
+ break;
case _PAGE_CACHE_WB:
err = _set_memory_wb(vaddr, nrpages);
break;
@@ -166,8 +169,13 @@
* Do not fallback to certain memory types with certain
* requested type:
* - request is uncached, return cannot be write-back
+ * - request is uncached, return cannot be write-combine
+ * - request is write-combine, return cannot be write-back
*/
if ((prot_val == _PAGE_CACHE_UC &&
+ (new_prot_val == _PAGE_CACHE_WB ||
+ new_prot_val == _PAGE_CACHE_WC)) ||
+ (prot_val == _PAGE_CACHE_WC &&
new_prot_val == _PAGE_CACHE_WB)) {
free_memtype(phys_addr, phys_addr + size);
return NULL;
@@ -180,6 +188,9 @@
default:
prot = PAGE_KERNEL_NOCACHE;
break;
+ case _PAGE_CACHE_WC:
+ prot = PAGE_KERNEL_WC;
+ break;
case _PAGE_CACHE_WB:
prot = PAGE_KERNEL;
break;
@@ -235,6 +246,25 @@
}
EXPORT_SYMBOL(ioremap_nocache);
+/**
+ * ioremap_wc - map memory into CPU space write combined
+ * @offset: bus address of the memory
+ * @size: size of the resource to map
+ *
+ * This version of ioremap ensures that the memory is marked write combining.
+ * Write combining allows faster writes to some hardware devices.
+ *
+ * Must be freed with iounmap.
+ */
+void __iomem *ioremap_wc(unsigned long phys_addr, unsigned long size)
+{
+ if (pat_wc_enabled)
+ return __ioremap(phys_addr, size, _PAGE_CACHE_WC);
+ else
+ return ioremap_nocache(phys_addr, size);
+}
+EXPORT_SYMBOL(ioremap_wc);
+
void __iomem *ioremap_cache(resource_size_t phys_addr, unsigned long size)
{
return __ioremap(phys_addr, size, _PAGE_CACHE_WB);
