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