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