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
9static 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
21static 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
28static 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 */
69void *memremap(resource_size_t offset, size_t size, unsigned long flags)
70{
71 int is_ram = region_intersects(offset, size,
72 IORESOURCE_SYSTEM_RAM, desc: 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(phys_addr: 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}
118EXPORT_SYMBOL(memremap);
119
120void memunmap(void *addr)
121{
122 if (is_ioremap_addr(x: addr))
123 iounmap(addr: (void __iomem *) addr);
124}
125EXPORT_SYMBOL(memunmap);
126
127static void devm_memremap_release(struct device *dev, void *res)
128{
129 memunmap(*(void **)res);
130}
131
132static int devm_memremap_match(struct device *dev, void *res, void *match_data)
133{
134 return *(void **)res == match_data;
135}
136
137void *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(error: -ENOMEM);
146
147 addr = memremap(offset, size, flags);
148 if (addr) {
149 *ptr = addr;
150 devres_add(dev, res: ptr);
151 } else {
152 devres_free(res: ptr);
153 return ERR_PTR(error: -ENXIO);
154 }
155
156 return addr;
157}
158EXPORT_SYMBOL(devm_memremap);
159
160void devm_memunmap(struct device *dev, void *addr)
161{
162 WARN_ON(devres_release(dev, devm_memremap_release,
163 devm_memremap_match, addr));
164}
165EXPORT_SYMBOL(devm_memunmap);
166

source code of linux/kernel/iomem.c