blob: dc2120776e1c3dc2c5b80d621a6e10abffbec6a7 [file] [log] [blame]
/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/device.h>
#include <linux/types.h>
#include <linux/io.h>
#include <linux/mm.h>
#include <linux/ioremap.h>
#ifndef arch_memremap_wb
static void *arch_memremap_wb(resource_size_t offset, unsigned long size)
#ifdef ioremap_cache
return (__force void *)ioremap_cache(offset, size);
return (__force void *)ioremap(offset, size);
#ifndef arch_memremap_can_ram_remap
static bool arch_memremap_can_ram_remap(resource_size_t offset, size_t size,
unsigned long flags)
return true;
static void *try_ram_remap(resource_size_t offset, size_t size,
unsigned long flags)
unsigned long pfn = PHYS_PFN(offset);
/* In the simple case just return the existing linear address */
if (pfn_valid(pfn) && !PageHighMem(pfn_to_page(pfn)) &&
arch_memremap_can_ram_remap(offset, size, flags))
return __va(offset);
return NULL; /* fallback to arch_memremap_wb */
* memremap() - remap an iomem_resource as cacheable memory
* @offset: iomem resource start address
* @size: size of remap
* 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. 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.
* Moreover, if MEMREMAP_WB is specified and the requested remap region is RAM
* memremap() will bypass establishing a new mapping and instead return
* a pointer into the direct map.
* MEMREMAP_WT - establish a mapping whereby writes either bypass the
* 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)
int is_ram = region_intersects(offset, size,
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);
return NULL;
/* Try all mapping types requested until one returns non-NULL */
if (flags & MEMREMAP_WB) {
* MEMREMAP_WB is special in that it can be satisfied
* from the direct map. Some archs depend on the
* capability of memremap() to autodetect cases where
* the requested range is potentially in System RAM.
if (is_ram == REGION_INTERSECTS)
addr = try_ram_remap(offset, size, flags);
if (!addr)
addr = arch_memremap_wb(offset, size);
* 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 != MEMREMAP_WB) {
WARN_ONCE(1, "memremap attempted on ram %pa size: %#lx\n",
&offset, (unsigned long) size);
return NULL;
if (!addr && (flags & MEMREMAP_WT))
addr = ioremap_wt(offset, size);
if (!addr && (flags & MEMREMAP_WC))
addr = ioremap_wc(offset, size);
return addr;
void memunmap(void *addr)
if (is_ioremap_addr(addr))
iounmap((void __iomem *) addr);
static void devm_memremap_release(struct device *dev, void *res)
memunmap(*(void **)res);
static int devm_memremap_match(struct device *dev, void *res, void *match_data)
return *(void **)res == match_data;
void *devm_memremap(struct device *dev, resource_size_t offset,
size_t size, unsigned long flags)
void **ptr, *addr;
ptr = devres_alloc_node(devm_memremap_release, sizeof(*ptr), GFP_KERNEL,
if (!ptr)
return ERR_PTR(-ENOMEM);
addr = memremap(offset, size, flags);
if (addr) {
*ptr = addr;
devres_add(dev, ptr);
} else {
return ERR_PTR(-ENXIO);
return addr;
void devm_memunmap(struct device *dev, void *addr)
WARN_ON(devres_release(dev, devm_memremap_release,
devm_memremap_match, addr));