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-rw-r--r--kernel/memremap.c13
1 files changed, 11 insertions, 2 deletions
diff --git a/kernel/memremap.c b/kernel/memremap.c
index e5e685e6ff2a..a6d382312e6f 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -41,11 +41,13 @@ static void *try_ram_remap(resource_size_t offset, size_t size)
* memremap() - remap an iomem_resource as cacheable memory
* @offset: iomem resource start address
* @size: size of remap
- * @flags: either MEMREMAP_WB or MEMREMAP_WT
+ * @flags: any of MEMREMAP_WB, MEMREMAP_WT and MEMREMAP_WC
*
* memremap() is "ioremap" for cases where it is known that the resource
* being mapped does not have i/o side effects and the __iomem
- * annotation is not applicable.
+ * annotation is not applicable. In the case of multiple flags, the different
+ * mapping types will be attempted in the order listed below until one of
+ * them succeeds.
*
* MEMREMAP_WB - matches the default mapping for System RAM on
* the architecture. This is usually a read-allocate write-back cache.
@@ -57,6 +59,10 @@ static void *try_ram_remap(resource_size_t offset, size_t size)
* cache or are written through to memory and never exist in a
* cache-dirty state with respect to program visibility. Attempts to
* map System RAM with this mapping type will fail.
+ *
+ * MEMREMAP_WC - establish a writecombine mapping, whereby writes may
+ * be coalesced together (e.g. in the CPU's write buffers), but is otherwise
+ * uncached. Attempts to map System RAM with this mapping type will fail.
*/
void *memremap(resource_size_t offset, size_t size, unsigned long flags)
{
@@ -102,6 +108,9 @@ void *memremap(resource_size_t offset, size_t size, unsigned long flags)
if (!addr && (flags & MEMREMAP_WT))
addr = ioremap_wt(offset, size);
+ if (!addr && (flags & MEMREMAP_WC))
+ addr = ioremap_wc(offset, size);
+
return addr;
}
EXPORT_SYMBOL(memremap);