Linux kernel mirror (for testing)
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linux
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#ifndef __PMEM_H__
14#define __PMEM_H__
15
16#include <linux/io.h>
17
18#ifdef CONFIG_ARCH_HAS_PMEM_API
19#include <asm/cacheflush.h>
20#else
21static inline void arch_wmb_pmem(void)
22{
23 BUG();
24}
25
26static inline bool __arch_has_wmb_pmem(void)
27{
28 return false;
29}
30
31static inline void __pmem *arch_memremap_pmem(resource_size_t offset,
32 unsigned long size)
33{
34 return NULL;
35}
36
37static inline void arch_memcpy_to_pmem(void __pmem *dst, const void *src,
38 size_t n)
39{
40 BUG();
41}
42#endif
43
44/*
45 * Architectures that define ARCH_HAS_PMEM_API must provide
46 * implementations for arch_memremap_pmem(), arch_memcpy_to_pmem(),
47 * arch_wmb_pmem(), and __arch_has_wmb_pmem().
48 */
49
50static inline void memcpy_from_pmem(void *dst, void __pmem const *src, size_t size)
51{
52 memcpy(dst, (void __force const *) src, size);
53}
54
55static inline void memunmap_pmem(void __pmem *addr)
56{
57 iounmap((void __force __iomem *) addr);
58}
59
60/**
61 * arch_has_wmb_pmem - true if wmb_pmem() ensures durability
62 *
63 * For a given cpu implementation within an architecture it is possible
64 * that wmb_pmem() resolves to a nop. In the case this returns
65 * false, pmem api users are unable to ensure durability and may want to
66 * fall back to a different data consistency model, or otherwise notify
67 * the user.
68 */
69static inline bool arch_has_wmb_pmem(void)
70{
71 if (IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API))
72 return __arch_has_wmb_pmem();
73 return false;
74}
75
76static inline bool arch_has_pmem_api(void)
77{
78 return IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API) && arch_has_wmb_pmem();
79}
80
81/*
82 * These defaults seek to offer decent performance and minimize the
83 * window between i/o completion and writes being durable on media.
84 * However, it is undefined / architecture specific whether
85 * default_memremap_pmem + default_memcpy_to_pmem is sufficient for
86 * making data durable relative to i/o completion.
87 */
88static void default_memcpy_to_pmem(void __pmem *dst, const void *src,
89 size_t size)
90{
91 memcpy((void __force *) dst, src, size);
92}
93
94static void __pmem *default_memremap_pmem(resource_size_t offset,
95 unsigned long size)
96{
97 return (void __pmem __force *)ioremap_wt(offset, size);
98}
99
100/**
101 * memremap_pmem - map physical persistent memory for pmem api
102 * @offset: physical address of persistent memory
103 * @size: size of the mapping
104 *
105 * Establish a mapping of the architecture specific memory type expected
106 * by memcpy_to_pmem() and wmb_pmem(). For example, it may be
107 * the case that an uncacheable or writethrough mapping is sufficient,
108 * or a writeback mapping provided memcpy_to_pmem() and
109 * wmb_pmem() arrange for the data to be written through the
110 * cache to persistent media.
111 */
112static inline void __pmem *memremap_pmem(resource_size_t offset,
113 unsigned long size)
114{
115 if (arch_has_pmem_api())
116 return arch_memremap_pmem(offset, size);
117 return default_memremap_pmem(offset, size);
118}
119
120/**
121 * memcpy_to_pmem - copy data to persistent memory
122 * @dst: destination buffer for the copy
123 * @src: source buffer for the copy
124 * @n: length of the copy in bytes
125 *
126 * Perform a memory copy that results in the destination of the copy
127 * being effectively evicted from, or never written to, the processor
128 * cache hierarchy after the copy completes. After memcpy_to_pmem()
129 * data may still reside in cpu or platform buffers, so this operation
130 * must be followed by a wmb_pmem().
131 */
132static inline void memcpy_to_pmem(void __pmem *dst, const void *src, size_t n)
133{
134 if (arch_has_pmem_api())
135 arch_memcpy_to_pmem(dst, src, n);
136 else
137 default_memcpy_to_pmem(dst, src, n);
138}
139
140/**
141 * wmb_pmem - synchronize writes to persistent memory
142 *
143 * After a series of memcpy_to_pmem() operations this drains data from
144 * cpu write buffers and any platform (memory controller) buffers to
145 * ensure that written data is durable on persistent memory media.
146 */
147static inline void wmb_pmem(void)
148{
149 if (arch_has_pmem_api())
150 arch_wmb_pmem();
151}
152#endif /* __PMEM_H__ */