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 /**
  28  * memremap() - remap an iomem_resource as cacheable memory
  29  * @offset: iomem resource start address
  30  * @size: size of remap
  31  * @flags: either MEMREMAP_WB or MEMREMAP_WT
  32  *
  33  * memremap() is "ioremap" for cases where it is known that the resource
  34  * being mapped does not have i/o side effects and the __iomem
  35  * annotation is not applicable.
  36  *
  37  * MEMREMAP_WB - matches the default mapping for "System RAM" on
  38  * the architecture.  This is usually a read-allocate write-back cache.
  39  * Morever, if MEMREMAP_WB is specified and the requested remap region is RAM
  40  * memremap() will bypass establishing a new mapping and instead return
  41  * a pointer into the direct map.
  42  *
  43  * MEMREMAP_WT - establish a mapping whereby writes either bypass the
  44  * cache or are written through to memory and never exist in a
  45  * cache-dirty state with respect to program visibility.  Attempts to
  46  * map "System RAM" with this mapping type will fail.
  47  */
  48 void *memremap(resource_size_t offset, size_t size, unsigned long flags)
  49 {
  50         int is_ram = region_intersects(offset, size, "System RAM");
  51         void *addr = NULL;
  52
  53         if (is_ram == REGION_MIXED) {
  54                 WARN_ONCE(1, "memremap attempted on mixed range %pa size: %#lx\n",
  55                                 &offset, (unsigned long) size);
  56                 return NULL;
  57         }
  58
  59         /* Try all mapping types requested until one returns non-NULL */
  60         if (flags & MEMREMAP_WB) {
  61                 flags &= ~MEMREMAP_WB;
  62                 /*
  63                  * MEMREMAP_WB is special in that it can be satisifed
  64                  * from the direct map.  Some archs depend on the
  65                  * capability of memremap() to autodetect cases where
  66                  * the requested range is potentially in "System RAM"
  67                  */
  68                 if (is_ram == REGION_INTERSECTS)
  69                         addr = __va(offset);
  70                 else
  71                         addr = ioremap_cache(offset, size);
  72         }
  73
  74         /*
  75          * If we don't have a mapping yet and more request flags are
  76          * pending then we will be attempting to establish a new virtual
  77          * address mapping.  Enforce that this mapping is not aliasing
  78          * "System RAM"
  79          */
  80         if (!addr && is_ram == REGION_INTERSECTS && flags) {
  81                 WARN_ONCE(1, "memremap attempted on ram %pa size: %#lx\n",
  82                                 &offset, (unsigned long) size);
  83                 return NULL;
  84         }
  85
  86         if (!addr && (flags & MEMREMAP_WT)) {
  87                 flags &= ~MEMREMAP_WT;
  88                 addr = ioremap_wt(offset, size);
  89         }
  90
  91         return addr;
  92 }
  93 EXPORT_SYMBOL(memremap);
  94
  95 void memunmap(void *addr)
  96 {
  97         if (is_vmalloc_addr(addr))
  98                 iounmap((void __iomem *) addr);
  99 }
 100 EXPORT_SYMBOL(memunmap);
 101
 102 static void devm_memremap_release(struct device *dev, void *res)
 103 {
 104         memunmap(res);
 105 }
 106
 107 static int devm_memremap_match(struct device *dev, void *res, void *match_data)
 108 {
 109         return *(void **)res == match_data;
 110 }
 111
 112 void *devm_memremap(struct device *dev, resource_size_t offset,
 113                 size_t size, unsigned long flags)
 114 {
 115         void **ptr, *addr;
 116
 117         ptr = devres_alloc(devm_memremap_release, sizeof(*ptr), GFP_KERNEL);
 118         if (!ptr)
 119                 return NULL;
 120
 121         addr = memremap(offset, size, flags);
 122         if (addr) {
 123                 *ptr = addr;
 124                 devres_add(dev, ptr);
 125         } else
 126                 devres_free(ptr);
 127
 128         return addr;
 129 }
 130 EXPORT_SYMBOL(devm_memremap);
 131
 132 void devm_memunmap(struct device *dev, void *addr)
 133 {
 134         WARN_ON(devres_destroy(dev, devm_memremap_release, devm_memremap_match,
 135                                addr));
 136         memunmap(addr);
 137 }
 138 EXPORT_SYMBOL(devm_memunmap);
 139
 140 #ifdef CONFIG_ZONE_DEVICE
 141 struct page_map {
 142         struct resource res;
 143 };
 144
 145 static void devm_memremap_pages_release(struct device *dev, void *res)
 146 {
 147         struct page_map *page_map = res;
 148
 149         /* pages are dead and unused, undo the arch mapping */
 150         arch_remove_memory(page_map->res.start, resource_size(&page_map->res));
 151 }
 152
 153 void *devm_memremap_pages(struct device *dev, struct resource *res)
 154 {
 155         int is_ram = region_intersects(res->start, resource_size(res),
 156                         "System RAM");
 157         struct page_map *page_map;
 158         int error, nid;
 159
 160         if (is_ram == REGION_MIXED) {
 161                 WARN_ONCE(1, "%s attempted on mixed region %pr\n",
 162                                 __func__, res);
 163                 return ERR_PTR(-ENXIO);
 164         }
 165
 166         if (is_ram == REGION_INTERSECTS)
 167                 return __va(res->start);
 168
 169         page_map = devres_alloc(devm_memremap_pages_release,
 170                         sizeof(*page_map), GFP_KERNEL);
 171         if (!page_map)
 172                 return ERR_PTR(-ENOMEM);
 173
 174         memcpy(&page_map->res, res, sizeof(*res));
 175
 176         nid = dev_to_node(dev);
 177         if (nid < 0)
 178                 nid = 0;
 179
 180         error = arch_add_memory(nid, res->start, resource_size(res), true);
 181         if (error) {
 182                 devres_free(page_map);
 183                 return ERR_PTR(error);
 184         }
 185
 186         devres_add(dev, page_map);
 187         return __va(res->start);
 188 }
 189 EXPORT_SYMBOL(devm_memremap_pages);
 190 #endif /* CONFIG_ZONE_DEVICE */