1 files changed, 42 insertions, 2 deletions
diff --git a/arch/x86/mm/iomap_32.c b/arch/x86/mm/iomap_32.c
index 6c2b1af16926..d5e28424622c 100644
--- a/arch/x86/mm/iomap_32.c
+++ b/arch/x86/mm/iomap_32.c
@@ -21,13 +21,13 @@
 #include <linux/module.h>
 
 #ifdef CONFIG_X86_PAE
-int
+static int
 is_io_mapping_possible(resource_size_t base, unsigned long size)
 {
 	return 1;
 }
 #else
-int
+static int
 is_io_mapping_possible(resource_size_t base, unsigned long size)
 {
 	/* There is no way to map greater than 1 << 32 address without PAE */
@@ -38,6 +38,46 @@ is_io_mapping_possible(resource_size_t base, unsigned long size)
 }
 #endif
 
+int
+reserve_io_memtype_wc(u64 base, unsigned long size, pgprot_t *prot)
+{
+	unsigned long ret_flag;
+
+	if (!is_io_mapping_possible(base, size))
+		goto out_err;
+
+	if (!pat_enabled) {
+		*prot = pgprot_noncached(PAGE_KERNEL);
+		return 0;
+	}
+
+	if (reserve_memtype(base, base + size, _PAGE_CACHE_WC, &ret_flag))
+		goto out_err;
+
+	if (ret_flag == _PAGE_CACHE_WB)
+		goto out_free;
+
+	if (kernel_map_sync_memtype(base, size, ret_flag))
+		goto out_free;
+
+	*prot = __pgprot(__PAGE_KERNEL | ret_flag);
+	return 0;
+
+out_free:
+	free_memtype(base, base + size);
+out_err:
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(reserve_io_memtype_wc);
+
+void
+free_io_memtype(u64 base, unsigned long size)
+{
+	if (pat_enabled)
+		free_memtype(base, base + size);
+}
+EXPORT_SYMBOL_GPL(free_io_memtype);
+
 /* Map 'pfn' using fixed map 'type' and protections 'prot'
  */
 void *