diff options
Diffstat (limited to 'kernel/memremap.c')
| -rw-r--r-- | kernel/memremap.c | 27 |
1 files changed, 18 insertions, 9 deletions
diff --git a/kernel/memremap.c b/kernel/memremap.c index 584febd13e2e..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) { @@ -64,6 +70,9 @@ void *memremap(resource_size_t offset, size_t size, unsigned long flags) IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE); void *addr = NULL; + if (!flags) + return NULL; + if (is_ram == REGION_MIXED) { WARN_ONCE(1, "memremap attempted on mixed range %pa size: %#lx\n", &offset, (unsigned long) size); @@ -72,7 +81,6 @@ void *memremap(resource_size_t offset, size_t size, unsigned long flags) /* Try all mapping types requested until one returns non-NULL */ if (flags & MEMREMAP_WB) { - flags &= ~MEMREMAP_WB; /* * MEMREMAP_WB is special in that it can be satisifed * from the direct map. Some archs depend on the @@ -86,21 +94,22 @@ void *memremap(resource_size_t offset, size_t size, unsigned long flags) } /* - * If we don't have a mapping yet and more request flags are - * pending then we will be attempting to establish a new virtual + * If we don't have a mapping yet and other request flags are + * present then we will be attempting to establish a new virtual * address mapping. Enforce that this mapping is not aliasing * System RAM. */ - if (!addr && is_ram == REGION_INTERSECTS && flags) { + if (!addr && is_ram == REGION_INTERSECTS && flags != MEMREMAP_WB) { WARN_ONCE(1, "memremap attempted on ram %pa size: %#lx\n", &offset, (unsigned long) size); return NULL; } - if (!addr && (flags & MEMREMAP_WT)) { - flags &= ~MEMREMAP_WT; + if (!addr && (flags & MEMREMAP_WT)) addr = ioremap_wt(offset, size); - } + + if (!addr && (flags & MEMREMAP_WC)) + addr = ioremap_wc(offset, size); return addr; } |