X-Git-Url: http://git.cascardo.info/?a=blobdiff_plain;f=include%2Flinux%2Fio.h;h=e2c8419278c192fd8002ae0b470ea2421dc51a57;hb=c636e176d8e5afe2f3b3e3f1de33ec13f1cee308;hp=32403b5716e5b8c4a5eb21bfad1f2e4bf7604501;hpb=79e24da00b1137031245f3341828e4215b1b5b59;p=cascardo%2Flinux.git

diff --git a/include/linux/io.h b/include/linux/io.h
index 32403b5716e5..82ef36eac8a1 100644
--- a/include/linux/io.h
+++ b/include/linux/io.h
@@ -135,9 +135,32 @@ enum {
 	/* See memremap() kernel-doc for usage description... */
 	MEMREMAP_WB = 1 << 0,
 	MEMREMAP_WT = 1 << 1,
+	MEMREMAP_WC = 1 << 2,
 };
 
 void *memremap(resource_size_t offset, size_t size, unsigned long flags);
 void memunmap(void *addr);
 
+/*
+ * On x86 PAT systems we have memory tracking that keeps track of
+ * the allowed mappings on memory ranges. This tracking works for
+ * all the in-kernel mapping APIs (ioremap*), but where the user
+ * wishes to map a range from a physical device into user memory
+ * the tracking won't be updated. This API is to be used by
+ * drivers which remap physical device pages into userspace,
+ * and wants to make sure they are mapped WC and not UC.
+ */
+#ifndef arch_io_reserve_memtype_wc
+static inline int arch_io_reserve_memtype_wc(resource_size_t base,
+					     resource_size_t size)
+{
+	return 0;
+}
+
+static inline void arch_io_free_memtype_wc(resource_size_t base,
+					   resource_size_t size)
+{
+}
+#endif
+
 #endif /* _LINUX_IO_H */