diff options
| -rw-r--r-- | include/linux/io.h | 1 | ||||
| -rw-r--r-- | kernel/memremap.c | 13 |
2 files changed, 12 insertions, 2 deletions
diff --git a/include/linux/io.h b/include/linux/io.h index 32403b5716e5..e2c8419278c1 100644 --- a/include/linux/io.h +++ b/include/linux/io.h @@ -135,6 +135,7 @@ enum { /* See memremap() kernel-doc for usage description... */ MEMREMAP_WB = 1 << 0, MEMREMAP_WT = 1 << 1, + MEMREMAP_WC = 1 << 2, }; void *memremap(resource_size_t offset, size_t size, unsigned long flags); 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); |