LXR linux/kernel/iomem.c

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#include <linux/device.h>
   3#include <linux/types.h>
   4#include <linux/io.h>
   5#include <linux/mm.h>
   6
   7#ifndef ioremap_cache
   8/* temporary while we convert existing ioremap_cache users to memremap */
   9__weak void __iomem *ioremap_cache(resource_size_t offset, unsigned long size)
  10{
  11        return ioremap(offset, size);
  12}
  13#endif
  14
  15#ifndef arch_memremap_wb
  16static void *arch_memremap_wb(resource_size_t offset, unsigned long size)
  17{
  18        return (__force void *)ioremap_cache(offset, size);
  19}
  20#endif
  21
  22#ifndef arch_memremap_can_ram_remap
  23static bool arch_memremap_can_ram_remap(resource_size_t offset, size_t size,
  24                                        unsigned long flags)
  25{
  26        return true;
  27}
  28#endif
  29
  30static void *try_ram_remap(resource_size_t offset, size_t size,
  31                           unsigned long flags)
  32{
  33        unsigned long pfn = PHYS_PFN(offset);
  34
  35        /* In the simple case just return the existing linear address */
  36        if (pfn_valid(pfn) && !PageHighMem(pfn_to_page(pfn)) &&
  37            arch_memremap_can_ram_remap(offset, size, flags))
  38                return __va(offset);
  39
  40        return NULL; /* fallback to arch_memremap_wb */
  41}
  42
  43/**
  44 * memremap() - remap an iomem_resource as cacheable memory
  45 * @offset: iomem resource start address
  46 * @size: size of remap
  47 * @flags: any of MEMREMAP_WB, MEMREMAP_WT, MEMREMAP_WC,
  48 *                MEMREMAP_ENC, MEMREMAP_DEC
  49 *
  50 * memremap() is "ioremap" for cases where it is known that the resource
  51 * being mapped does not have i/o side effects and the __iomem
  52 * annotation is not applicable. In the case of multiple flags, the different
  53 * mapping types will be attempted in the order listed below until one of
  54 * them succeeds.
  55 *
  56 * MEMREMAP_WB - matches the default mapping for System RAM on
  57 * the architecture.  This is usually a read-allocate write-back cache.
  58 * Morever, if MEMREMAP_WB is specified and the requested remap region is RAM
  59 * memremap() will bypass establishing a new mapping and instead return
  60 * a pointer into the direct map.
  61 *
  62 * MEMREMAP_WT - establish a mapping whereby writes either bypass the
  63 * cache or are written through to memory and never exist in a
  64 * cache-dirty state with respect to program visibility.  Attempts to
  65 * map System RAM with this mapping type will fail.
  66 *
  67 * MEMREMAP_WC - establish a writecombine mapping, whereby writes may
  68 * be coalesced together (e.g. in the CPU's write buffers), but is otherwise
  69 * uncached. Attempts to map System RAM with this mapping type will fail.
  70 */
  71void *memremap(resource_size_t offset, size_t size, unsigned long flags)
  72{
  73        int is_ram = region_intersects(offset, size,
  74                                       IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
  75        void *addr = NULL;
  76
  77        if (!flags)
  78                return NULL;
  79
  80        if (is_ram == REGION_MIXED) {
  81                WARN_ONCE(1, "memremap attempted on mixed range %pa size: %#lx\n",
  82                                &offset, (unsigned long) size);
  83                return NULL;
  84        }
  85
  86        /* Try all mapping types requested until one returns non-NULL */
  87        if (flags & MEMREMAP_WB) {
  88                /*
  89                 * MEMREMAP_WB is special in that it can be satisifed
  90                 * from the direct map.  Some archs depend on the
  91                 * capability of memremap() to autodetect cases where
  92                 * the requested range is potentially in System RAM.
  93                 */
  94                if (is_ram == REGION_INTERSECTS)
  95                        addr = try_ram_remap(offset, size, flags);
  96                if (!addr)
  97                        addr = arch_memremap_wb(offset, size);
  98        }
  99
 100        /*
 101         * If we don't have a mapping yet and other request flags are
 102         * present then we will be attempting to establish a new virtual
 103         * address mapping.  Enforce that this mapping is not aliasing
 104         * System RAM.
 105         */
 106        if (!addr && is_ram == REGION_INTERSECTS && flags != MEMREMAP_WB) {
 107                WARN_ONCE(1, "memremap attempted on ram %pa size: %#lx\n",
 108                                &offset, (unsigned long) size);
 109                return NULL;
 110        }
 111
 112        if (!addr && (flags & MEMREMAP_WT))
 113                addr = ioremap_wt(offset, size);
 114
 115        if (!addr && (flags & MEMREMAP_WC))
 116                addr = ioremap_wc(offset, size);
 117
 118        return addr;
 119}
 120EXPORT_SYMBOL(memremap);
 121
 122void memunmap(void *addr)
 123{
 124        if (is_vmalloc_addr(addr))
 125                iounmap((void __iomem *) addr);
 126}
 127EXPORT_SYMBOL(memunmap);
 128
 129static void devm_memremap_release(struct device *dev, void *res)
 130{
 131        memunmap(*(void **)res);
 132}
 133
 134static int devm_memremap_match(struct device *dev, void *res, void *match_data)
 135{
 136        return *(void **)res == match_data;
 137}
 138
 139void *devm_memremap(struct device *dev, resource_size_t offset,
 140                size_t size, unsigned long flags)
 141{
 142        void **ptr, *addr;
 143
 144        ptr = devres_alloc_node(devm_memremap_release, sizeof(*ptr), GFP_KERNEL,
 145                        dev_to_node(dev));
 146        if (!ptr)
 147                return ERR_PTR(-ENOMEM);
 148
 149        addr = memremap(offset, size, flags);
 150        if (addr) {
 151                *ptr = addr;
 152                devres_add(dev, ptr);
 153        } else {
 154                devres_free(ptr);
 155                return ERR_PTR(-ENXIO);
 156        }
 157
 158        return addr;
 159}
 160EXPORT_SYMBOL(devm_memremap);
 161
 162void devm_memunmap(struct device *dev, void *addr)
 163{
 164        WARN_ON(devres_release(dev, devm_memremap_release,
 165                                devm_memremap_match, addr));
 166}
 167EXPORT_SYMBOL(devm_memunmap);
 168