kernel/memremap.c

   1 /*
   2  * Copyright(c) 2015 Intel Corporation. All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of version 2 of the GNU General Public License as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  */
  13 #include <linux/device.h>
  14 #include <linux/types.h>
  15 #include <linux/io.h>
  16 #include <linux/mm.h>
  17 #include <linux/memory_hotplug.h>
  18
  19 #ifndef ioremap_cache
  20 /* temporary while we convert existing ioremap_cache users to memremap */
  21 __weak void __iomem *ioremap_cache(resource_size_t offset, unsigned long size)
  22 {
  23         return ioremap(offset, size);
  24 }
  25 #endif
  26
  27 static void *try_ram_remap(resource_size_t offset, size_t size)
  28 {
  29         struct page *page = pfn_to_page(offset >> PAGE_SHIFT);
  30
  31         /* In the simple case just return the existing linear address */
  32         if (!PageHighMem(page))
  33                 return __va(offset);
  34         return NULL; /* fallback to ioremap_cache */
  35 }
  36
  37 /**
  38  * memremap() - remap an iomem_resource as cacheable memory
  39  * @offset: iomem resource start address
  40  * @size: size of remap
  41  * @flags: either MEMREMAP_WB or MEMREMAP_WT
  42  *
  43  * memremap() is "ioremap" for cases where it is known that the resource
  44  * being mapped does not have i/o side effects and the __iomem
  45  * annotation is not applicable.
  46  *
  47  * MEMREMAP_WB - matches the default mapping for "System RAM" on
  48  * the architecture.  This is usually a read-allocate write-back cache.
  49  * Morever, if MEMREMAP_WB is specified and the requested remap region is RAM
  50  * memremap() will bypass establishing a new mapping and instead return
  51  * a pointer into the direct map.
  52  *
  53  * MEMREMAP_WT - establish a mapping whereby writes either bypass the
  54  * cache or are written through to memory and never exist in a
  55  * cache-dirty state with respect to program visibility.  Attempts to
  56  * map "System RAM" with this mapping type will fail.
  57  */
  58 void *memremap(resource_size_t offset, size_t size, unsigned long flags)
  59 {
  60         int is_ram = region_intersects(offset, size, "System RAM");
  61         void *addr = NULL;
  62
  63         if (is_ram == REGION_MIXED) {
  64                 WARN_ONCE(1, "memremap attempted on mixed range %pa size: %#lx\n",
  65                                 &offset, (unsigned long) size);
  66                 return NULL;
  67         }
  68
  69         /* Try all mapping types requested until one returns non-NULL */
  70         if (flags & MEMREMAP_WB) {
  71                 flags &= ~MEMREMAP_WB;
  72                 /*
  73                  * MEMREMAP_WB is special in that it can be satisifed
  74                  * from the direct map.  Some archs depend on the
  75                  * capability of memremap() to autodetect cases where
  76                  * the requested range is potentially in "System RAM"
  77                  */
  78                 if (is_ram == REGION_INTERSECTS)
  79                         addr = try_ram_remap(offset, size);
  80                 if (!addr)
  81                         addr = ioremap_cache(offset, size);
  82         }
  83
  84         /*
  85          * If we don't have a mapping yet and more request flags are
  86          * pending then we will be attempting to establish a new virtual
  87          * address mapping.  Enforce that this mapping is not aliasing
  88          * "System RAM"
  89          */
  90         if (!addr && is_ram == REGION_INTERSECTS && flags) {
  91                 WARN_ONCE(1, "memremap attempted on ram %pa size: %#lx\n",
  92                                 &offset, (unsigned long) size);
  93                 return NULL;
  94         }
  95
  96         if (!addr && (flags & MEMREMAP_WT)) {
  97                 flags &= ~MEMREMAP_WT;
  98                 addr = ioremap_wt(offset, size);
  99         }
 100
 101         return addr;
 102 }
 103 EXPORT_SYMBOL(memremap);
 104
 105 void memunmap(void *addr)
 106 {
 107         if (is_vmalloc_addr(addr))
 108                 iounmap((void __iomem *) addr);
 109 }
 110 EXPORT_SYMBOL(memunmap);
 111
 112 static void devm_memremap_release(struct device *dev, void *res)
 113 {
 114         memunmap(*(void **)res);
 115 }
 116
 117 static int devm_memremap_match(struct device *dev, void *res, void *match_data)
 118 {
 119         return *(void **)res == match_data;
 120 }
 121
 122 void *devm_memremap(struct device *dev, resource_size_t offset,
 123                 size_t size, unsigned long flags)
 124 {
 125         void **ptr, *addr;
 126
 127         ptr = devres_alloc_node(devm_memremap_release, sizeof(*ptr), GFP_KERNEL,
 128                         dev_to_node(dev));
 129         if (!ptr)
 130                 return ERR_PTR(-ENOMEM);
 131
 132         addr = memremap(offset, size, flags);
 133         if (addr) {
 134                 *ptr = addr;
 135                 devres_add(dev, ptr);
 136         } else {
 137                 devres_free(ptr);
 138                 return ERR_PTR(-ENXIO);
 139         }
 140
 141         return addr;
 142 }
 143 EXPORT_SYMBOL(devm_memremap);
 144
 145 void devm_memunmap(struct device *dev, void *addr)
 146 {
 147         WARN_ON(devres_release(dev, devm_memremap_release,
 148                                 devm_memremap_match, addr));
 149 }
 150 EXPORT_SYMBOL(devm_memunmap);
 151
 152 #ifdef CONFIG_ZONE_DEVICE
 153 struct page_map {
 154         struct resource res;
 155 };
 156
 157 static void devm_memremap_pages_release(struct device *dev, void *res)
 158 {
 159         struct page_map *page_map = res;
 160
 161         /* pages are dead and unused, undo the arch mapping */
 162         mem_hotplug_begin();
 163         arch_remove_memory(page_map->res.start, resource_size(&page_map->res));
 164         mem_hotplug_done();
 165 }
 166
 167 void *devm_memremap_pages(struct device *dev, struct resource *res)
 168 {
 169         int is_ram = region_intersects(res->start, resource_size(res),
 170                         "System RAM");
 171         struct page_map *page_map;
 172         int error, nid;
 173
 174         if (is_ram == REGION_MIXED) {
 175                 WARN_ONCE(1, "%s attempted on mixed region %pr\n",
 176                                 __func__, res);
 177                 return ERR_PTR(-ENXIO);
 178         }
 179
 180         if (is_ram == REGION_INTERSECTS)
 181                 return __va(res->start);
 182
 183         page_map = devres_alloc_node(devm_memremap_pages_release,
 184                         sizeof(*page_map), GFP_KERNEL, dev_to_node(dev));
 185         if (!page_map)
 186                 return ERR_PTR(-ENOMEM);
 187
 188         memcpy(&page_map->res, res, sizeof(*res));
 189
 190         nid = dev_to_node(dev);
 191         if (nid < 0)
 192                 nid = numa_mem_id();
 193
 194         mem_hotplug_begin();
 195         error = arch_add_memory(nid, res->start, resource_size(res), true);
 196         mem_hotplug_done();
 197         if (error) {
 198                 devres_free(page_map);
 199                 return ERR_PTR(error);
 200         }
 201
 202         devres_add(dev, page_map);
 203         return __va(res->start);
 204 }
 205 EXPORT_SYMBOL(devm_memremap_pages);
 206 #endif /* CONFIG_ZONE_DEVICE */