memremap: fix highmem support

[karo-tx-linux.git] / kernel / memremap.c

diff --git a/kernel/memremap.c b/kernel/memremap.c
index 72b0c66628b6b3db589ad0cd6ed6533edb68a9ea..9d6b55587eaa59a25c38776e43aeff51ba682c40 100644 (file)
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -24,6 +24,16 @@ __weak void __iomem *ioremap_cache(resource_size_t offset, unsigned long size)
 }
 #endif
 
+static void *try_ram_remap(resource_size_t offset, size_t size)
+{
+       struct page *page = pfn_to_page(offset >> PAGE_SHIFT);
+
+       /* In the simple case just return the existing linear address */
+       if (!PageHighMem(page))
+               return __va(offset);
+       return NULL; /* fallback to ioremap_cache */
+}
+
 /**
  * memremap() - remap an iomem_resource as cacheable memory
  * @offset: iomem resource start address
@@ -66,8 +76,8 @@ void *memremap(resource_size_t offset, size_t size, unsigned long flags)
                 * the requested range is potentially in "System RAM"
                 */
                if (is_ram == REGION_INTERSECTS)
-                       addr = __va(offset);
-               else
+                       addr = try_ram_remap(offset, size);
+               if (!addr)
                        addr = ioremap_cache(offset, size);
        }