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 
7 #ifndef ioremap_cache
8 /* temporary while we convert existing ioremap_cache users to memremap */
ioremap_cache(resource_size_t offset,unsigned long size)9 __weak void __iomem *ioremap_cache(resource_size_t offset, unsigned long size)
10 {
11 	return ioremap(offset, size);
12 }
13 #endif
14 
15 #ifndef arch_memremap_wb
arch_memremap_wb(resource_size_t offset,unsigned long size)16 static void *arch_memremap_wb(resource_size_t offset, unsigned long size)
17 {
18 	return (__force void *)ioremap_cache(offset, size);
19 }
20 #endif
21 
22 #ifndef arch_memremap_can_ram_remap
arch_memremap_can_ram_remap(resource_size_t offset,size_t size,unsigned long flags)23 static bool arch_memremap_can_ram_remap(resource_size_t offset, size_t size,
24 					unsigned long flags)
25 {
26 	return true;
27 }
28 #endif
29 
try_ram_remap(resource_size_t offset,size_t size,unsigned long flags)30 static void *try_ram_remap(resource_size_t offset, size_t size,
31 			   unsigned long flags)
32 {
33 	unsigned long pfn = PHYS_PFN(offset);
34 
35 	/* In the simple case just return the existing linear address */
36 	if (pfn_valid(pfn) && !PageHighMem(pfn_to_page(pfn)) &&
37 	    arch_memremap_can_ram_remap(offset, size, flags))
38 		return __va(offset);
39 
40 	return NULL; /* fallback to arch_memremap_wb */
41 }
42 
43 /**
44  * memremap() - remap an iomem_resource as cacheable memory
45  * @offset: iomem resource start address
46  * @size: size of remap
47  * @flags: any of MEMREMAP_WB, MEMREMAP_WT, MEMREMAP_WC,
48  *		  MEMREMAP_ENC, MEMREMAP_DEC
49  *
50  * memremap() is "ioremap" for cases where it is known that the resource
51  * being mapped does not have i/o side effects and the __iomem
52  * annotation is not applicable. In the case of multiple flags, the different
53  * mapping types will be attempted in the order listed below until one of
54  * them succeeds.
55  *
56  * MEMREMAP_WB - matches the default mapping for System RAM on
57  * the architecture.  This is usually a read-allocate write-back cache.
58  * Moreover, if MEMREMAP_WB is specified and the requested remap region is RAM
59  * memremap() will bypass establishing a new mapping and instead return
60  * a pointer into the direct map.
61  *
62  * MEMREMAP_WT - establish a mapping whereby writes either bypass the
63  * cache or are written through to memory and never exist in a
64  * cache-dirty state with respect to program visibility.  Attempts to
65  * map System RAM with this mapping type will fail.
66  *
67  * MEMREMAP_WC - establish a writecombine mapping, whereby writes may
68  * be coalesced together (e.g. in the CPU's write buffers), but is otherwise
69  * uncached. Attempts to map System RAM with this mapping type will fail.
70  */
memremap(resource_size_t offset,size_t size,unsigned long flags)71 void *memremap(resource_size_t offset, size_t size, unsigned long flags)
72 {
73 	int is_ram = region_intersects(offset, size,
74 				       IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
75 	void *addr = NULL;
76 
77 	if (!flags)
78 		return NULL;
79 
80 	if (is_ram == REGION_MIXED) {
81 		WARN_ONCE(1, "memremap attempted on mixed range %pa size: %#lx\n",
82 				&offset, (unsigned long) size);
83 		return NULL;
84 	}
85 
86 	/* Try all mapping types requested until one returns non-NULL */
87 	if (flags & MEMREMAP_WB) {
88 		/*
89 		 * MEMREMAP_WB is special in that it can be satisfied
90 		 * from the direct map.  Some archs depend on the
91 		 * capability of memremap() to autodetect cases where
92 		 * the requested range is potentially in System RAM.
93 		 */
94 		if (is_ram == REGION_INTERSECTS)
95 			addr = try_ram_remap(offset, size, flags);
96 		if (!addr)
97 			addr = arch_memremap_wb(offset, size);
98 	}
99 
100 	/*
101 	 * If we don't have a mapping yet and other request flags are
102 	 * present then we will be attempting to establish a new virtual
103 	 * address mapping.  Enforce that this mapping is not aliasing
104 	 * System RAM.
105 	 */
106 	if (!addr && is_ram == REGION_INTERSECTS && flags != MEMREMAP_WB) {
107 		WARN_ONCE(1, "memremap attempted on ram %pa size: %#lx\n",
108 				&offset, (unsigned long) size);
109 		return NULL;
110 	}
111 
112 	if (!addr && (flags & MEMREMAP_WT))
113 		addr = ioremap_wt(offset, size);
114 
115 	if (!addr && (flags & MEMREMAP_WC))
116 		addr = ioremap_wc(offset, size);
117 
118 	return addr;
119 }
120 EXPORT_SYMBOL(memremap);
121 
memunmap(void * addr)122 void memunmap(void *addr)
123 {
124 	if (is_ioremap_addr(addr))
125 		iounmap((void __iomem *) addr);
126 }
127 EXPORT_SYMBOL(memunmap);
128 
devm_memremap_release(struct device * dev,void * res)129 static void devm_memremap_release(struct device *dev, void *res)
130 {
131 	memunmap(*(void **)res);
132 }
133 
devm_memremap_match(struct device * dev,void * res,void * match_data)134 static int devm_memremap_match(struct device *dev, void *res, void *match_data)
135 {
136 	return *(void **)res == match_data;
137 }
138 
devm_memremap(struct device * dev,resource_size_t offset,size_t size,unsigned long flags)139 void *devm_memremap(struct device *dev, resource_size_t offset,
140 		size_t size, unsigned long flags)
141 {
142 	void **ptr, *addr;
143 
144 	ptr = devres_alloc_node(devm_memremap_release, sizeof(*ptr), GFP_KERNEL,
145 			dev_to_node(dev));
146 	if (!ptr)
147 		return ERR_PTR(-ENOMEM);
148 
149 	addr = memremap(offset, size, flags);
150 	if (addr) {
151 		*ptr = addr;
152 		devres_add(dev, ptr);
153 	} else {
154 		devres_free(ptr);
155 		return ERR_PTR(-ENXIO);
156 	}
157 
158 	return addr;
159 }
160 EXPORT_SYMBOL(devm_memremap);
161 
devm_memunmap(struct device * dev,void * addr)162 void devm_memunmap(struct device *dev, void *addr)
163 {
164 	WARN_ON(devres_release(dev, devm_memremap_release,
165 				devm_memremap_match, addr));
166 }
167 EXPORT_SYMBOL(devm_memunmap);
168