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