1 files changed, 36 insertions, 53 deletions

diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index d02806513670..325fc98cc9ff 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -922,39 +922,17 @@ static inline void *phys_to_virt(unsigned long address)
 /**
  * DOC: ioremap() and ioremap_*() variants
  *
- * If you have an IOMMU your architecture is expected to have both ioremap()
- * and iounmap() implemented otherwise the asm-generic helpers will provide a
- * direct mapping.
+ * Architectures with an MMU are expected to provide ioremap() and iounmap()
+ * themselves or rely on GENERIC_IOREMAP.  For NOMMU architectures we provide
+ * a default nop-op implementation that expect that the physical address used
+ * for MMIO are already marked as uncached, and can be used as kernel virtual
+ * addresses.
  *
- * There are ioremap_*() call variants, if you have no IOMMU we naturally will
- * default to direct mapping for all of them, you can override these defaults.
- * If you have an IOMMU you are highly encouraged to provide your own
- * ioremap variant implementation as there currently is no safe architecture
- * agnostic default. To avoid possible improper behaviour default asm-generic
- * ioremap_*() variants all return NULL when an IOMMU is available. If you've
- * defined your own ioremap_*() variant you must then declare your own
- * ioremap_*() variant as defined to itself to avoid the default NULL return.
+ * ioremap_wc() and ioremap_wt() can provide more relaxed caching attributes
+ * for specific drivers if the architecture choses to implement them.  If they
+ * are not implemented we fall back to plain ioremap.
  */
-
-#ifdef CONFIG_MMU
-
-#ifndef ioremap_uc
-#define ioremap_uc ioremap_uc
-static inline void __iomem *ioremap_uc(phys_addr_t offset, size_t size)
-{
-	return NULL;
-}
-#endif
-
-#else /* !CONFIG_MMU */
-
-/*
- * Change "struct page" to physical address.
- *
- * This implementation is for the no-MMU case only... if you have an MMU
- * you'll need to provide your own definitions.
- */
-
+#ifndef CONFIG_MMU
 #ifndef ioremap
 #define ioremap ioremap
 static inline void __iomem *ioremap(phys_addr_t offset, size_t size)
@@ -965,42 +943,47 @@ static inline void __iomem *ioremap(phys_addr_t offset, size_t size)
 
 #ifndef iounmap
 #define iounmap iounmap
-
 static inline void iounmap(void __iomem *addr)
 {
 }
 #endif
-#endif /* CONFIG_MMU */
-#ifndef ioremap_nocache
-void __iomem *ioremap(phys_addr_t phys_addr, size_t size);
-#define ioremap_nocache ioremap_nocache
-static inline void __iomem *ioremap_nocache(phys_addr_t offset, size_t size)
-{
-	return ioremap(offset, size);
-}
-#endif
+#elif defined(CONFIG_GENERIC_IOREMAP)
+#include <asm/pgtable.h>
 
-#ifndef ioremap_uc
-#define ioremap_uc ioremap_uc
-static inline void __iomem *ioremap_uc(phys_addr_t offset, size_t size)
+void __iomem *ioremap_prot(phys_addr_t addr, size_t size, unsigned long prot);
+void iounmap(volatile void __iomem *addr);
+
+static inline void __iomem *ioremap(phys_addr_t addr, size_t size)
 {
-	return ioremap_nocache(offset, size);
+	/* _PAGE_IOREMAP needs to be supplied by the architecture */
+	return ioremap_prot(addr, size, _PAGE_IOREMAP);
 }
+#endif /* !CONFIG_MMU || CONFIG_GENERIC_IOREMAP */
+
+#ifndef ioremap_nocache
+#define ioremap_nocache ioremap
 #endif
 
 #ifndef ioremap_wc
-#define ioremap_wc ioremap_wc
-static inline void __iomem *ioremap_wc(phys_addr_t offset, size_t size)
-{
-	return ioremap_nocache(offset, size);
-}
+#define ioremap_wc ioremap
 #endif
 
 #ifndef ioremap_wt
-#define ioremap_wt ioremap_wt
-static inline void __iomem *ioremap_wt(phys_addr_t offset, size_t size)
+#define ioremap_wt ioremap
+#endif
+
+/*
+ * ioremap_uc is special in that we do require an explicit architecture
+ * implementation.  In general you do not want to use this function in a
+ * driver and use plain ioremap, which is uncached by default.  Similarly
+ * architectures should not implement it unless they have a very good
+ * reason.
+ */
+#ifndef ioremap_uc
+#define ioremap_uc ioremap_uc
+static inline void __iomem *ioremap_uc(phys_addr_t offset, size_t size)
 {
-	return ioremap_nocache(offset, size);
+	return NULL;
 }
 #endif