* 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.
* 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)
{
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);
/* 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
}
/*
- * 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;
}
/*
* 'memmap_start' is the virtual address for the first "struct
* page" in this range of the vmemmap array. In the case of
- * CONFIG_SPARSE_VMEMMAP a page_to_pfn conversion is simple
+ * CONFIG_SPARSEMEM_VMEMMAP a page_to_pfn conversion is simple
* pointer arithmetic, so we can perform this to_vmem_altmap()
* conversion without concern for the initialization state of
* the struct page fields.
struct dev_pagemap *pgmap;
/*
- * Uncoditionally retrieve a dev_pagemap associated with the
+ * Unconditionally retrieve a dev_pagemap associated with the
* given physical address, this is only for use in the
* arch_{add|remove}_memory() for setting up and tearing down
* the memmap.