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-rw-r--r--arch/x86/include/asm/io.h6
-rw-r--r--arch/x86/mm/pat.c14
-rw-r--r--include/linux/io.h22
3 files changed, 42 insertions, 0 deletions
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index de25aad07853..d34bd370074b 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -351,4 +351,10 @@ extern void arch_phys_wc_del(int handle);
#define arch_phys_wc_add arch_phys_wc_add
#endif
+#ifdef CONFIG_X86_PAT
+extern int arch_io_reserve_memtype_wc(resource_size_t start, resource_size_t size);
+extern void arch_io_free_memtype_wc(resource_size_t start, resource_size_t size);
+#define arch_io_reserve_memtype_wc arch_io_reserve_memtype_wc
+#endif
+
#endif /* _ASM_X86_IO_H */
diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 170cc4ff057b..83e701f160a9 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -730,6 +730,20 @@ void io_free_memtype(resource_size_t start, resource_size_t end)
free_memtype(start, end);
}
+int arch_io_reserve_memtype_wc(resource_size_t start, resource_size_t size)
+{
+ enum page_cache_mode type = _PAGE_CACHE_MODE_WC;
+
+ return io_reserve_memtype(start, start + size, &type);
+}
+EXPORT_SYMBOL(arch_io_reserve_memtype_wc);
+
+void arch_io_free_memtype_wc(resource_size_t start, resource_size_t size)
+{
+ io_free_memtype(start, start + size);
+}
+EXPORT_SYMBOL(arch_io_free_memtype_wc);
+
pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
unsigned long size, pgprot_t vma_prot)
{
diff --git a/include/linux/io.h b/include/linux/io.h
index e2c8419278c1..82ef36eac8a1 100644
--- a/include/linux/io.h
+++ b/include/linux/io.h
@@ -141,4 +141,26 @@ enum {
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 */