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
  16 static 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
  23 static 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
  30 static 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  * Moreover, 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  */
  71 void *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 satisfied
  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 }
 120 EXPORT_SYMBOL(memremap);
 121
 122 void memunmap(void *addr)
 123 {
 124         if (is_ioremap_addr(addr))
 125                 iounmap((void __iomem *) addr);
 126 }
 127 EXPORT_SYMBOL(memunmap);
 128
 129 static void devm_memremap_release(struct device *dev, void *res)
 130 {
 131         memunmap(*(void **)res);
 132 }
 133
 134 static int devm_memremap_match(struct device *dev, void *res, void *match_data)
 135 {
 136         return *(void **)res == match_data;
 137 }
 138
 139 void *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 }
 160 EXPORT_SYMBOL(devm_memremap);
 161
 162 void devm_memunmap(struct device *dev, void *addr)
 163 {
 164         WARN_ON(devres_release(dev, devm_memremap_release,
 165                                 devm_memremap_match, addr));
 166 }
 167 EXPORT_SYMBOL(devm_memunmap);