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-rw-r--r--include/asm-generic/io.h21
1 files changed, 20 insertions, 1 deletions
diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index c6af40ce03be..76d456c516a1 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -942,7 +942,9 @@ static inline void *phys_to_virt(unsigned long address)
*
* 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.
+ * are not implemented we fall back to plain ioremap. Conversely, ioremap_np()
+ * can provide stricter non-posted write semantics if the architecture
+ * implements them.
*/
#ifndef CONFIG_MMU
#ifndef ioremap
@@ -995,6 +997,23 @@ static inline void __iomem *ioremap_uc(phys_addr_t offset, size_t size)
}
#endif
+/*
+ * ioremap_np needs an explicit architecture implementation, as it
+ * requests stronger semantics than regular ioremap(). Portable drivers
+ * should instead use one of the higher-level abstractions, like
+ * devm_ioremap_resource(), to choose the correct variant for any given
+ * device and bus. Portable drivers with a good reason to want non-posted
+ * write semantics should always provide an ioremap() fallback in case
+ * ioremap_np() is not available.
+ */
+#ifndef ioremap_np
+#define ioremap_np ioremap_np
+static inline void __iomem *ioremap_np(phys_addr_t offset, size_t size)
+{
+ return NULL;
+}
+#endif
+
#ifdef CONFIG_HAS_IOPORT_MAP
#ifndef CONFIG_GENERIC_IOMAP
#ifndef ioport_map