linux/kernel/iomem.c

/* 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)
{ … }
#endif

#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;
}
#endif

static void *try_ram_remap(resource_size_t offset, size_t size,
			   unsigned long flags)
{ … }

/**
 * memremap() - remap an iomem_resource as cacheable memory
 * @offset: iomem resource start address
 * @size: size of remap
 * @flags: any of MEMREMAP_WB, MEMREMAP_WT, MEMREMAP_WC,
 *		  MEMREMAP_ENC, MEMREMAP_DEC
 *
 * 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)
{ … }
EXPORT_SYMBOL(…);

void memunmap(void *addr)
{ … }
EXPORT_SYMBOL(…);

static void devm_memremap_release(struct device *dev, void *res)
{ … }

static int devm_memremap_match(struct device *dev, void *res, void *match_data)
{ … }

void *devm_memremap(struct device *dev, resource_size_t offset,
		size_t size, unsigned long flags)
{ … }
EXPORT_SYMBOL(…);

void devm_memunmap(struct device *dev, void *addr)
{ … }
EXPORT_SYMBOL(…);