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#include <linux/uio.h>
18
19#ifdef CONFIG_ARCH_HAS_PMEM_API
20#define ARCH_MEMREMAP_PMEM MEMREMAP_WB
21#include <asm/pmem.h>
22#else
23#define ARCH_MEMREMAP_PMEM MEMREMAP_WT
24/*
25 * These are simply here to enable compilation, all call sites gate
26 * calling these symbols with arch_has_pmem_api() and redirect to the
27 * implementation in asm/pmem.h.
28 */
29static inline bool __arch_has_wmb_pmem(void)
30{
31	return false;
32}
33
34static inline void arch_wmb_pmem(void)
35{
36	BUG();
37}
38
39static inline void arch_memcpy_to_pmem(void __pmem *dst, const void *src,
40		size_t n)
41{
42	BUG();
43}
44
45static inline size_t arch_copy_from_iter_pmem(void __pmem *addr, size_t bytes,
46		struct iov_iter *i)
47{
48	BUG();
49	return 0;
50}
51
52static inline void arch_clear_pmem(void __pmem *addr, size_t size)
53{
54	BUG();
55}
56#endif
57
58/*
59 * Architectures that define ARCH_HAS_PMEM_API must provide
60 * implementations for arch_memcpy_to_pmem(), arch_wmb_pmem(),
61 * arch_copy_from_iter_pmem(), arch_clear_pmem() and arch_has_wmb_pmem().
62 */
63static inline void memcpy_from_pmem(void *dst, void __pmem const *src, size_t size)
64{
65	memcpy(dst, (void __force const *) src, size);
66}
67
68static inline bool arch_has_pmem_api(void)
69{
70	return IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API);
71}
72
73/**
74 * arch_has_wmb_pmem - true if wmb_pmem() ensures durability
75 *
76 * For a given cpu implementation within an architecture it is possible
77 * that wmb_pmem() resolves to a nop.  In the case this returns
78 * false, pmem api users are unable to ensure durability and may want to
79 * fall back to a different data consistency model, or otherwise notify
80 * the user.
81 */
82static inline bool arch_has_wmb_pmem(void)
83{
84	return arch_has_pmem_api() && __arch_has_wmb_pmem();
85}
86
87/*
88 * These defaults seek to offer decent performance and minimize the
89 * window between i/o completion and writes being durable on media.
90 * However, it is undefined / architecture specific whether
91 * ARCH_MEMREMAP_PMEM + default_memcpy_to_pmem is sufficient for
92 * making data durable relative to i/o completion.
93 */
94static inline void default_memcpy_to_pmem(void __pmem *dst, const void *src,
95		size_t size)
96{
97	memcpy((void __force *) dst, src, size);
98}
99
100static inline size_t default_copy_from_iter_pmem(void __pmem *addr,
101		size_t bytes, struct iov_iter *i)
102{
103	return copy_from_iter_nocache((void __force *)addr, bytes, i);
104}
105
106static inline void default_clear_pmem(void __pmem *addr, size_t size)
107{
108	if (size == PAGE_SIZE && ((unsigned long)addr & ~PAGE_MASK) == 0)
109		clear_page((void __force *)addr);
110	else
111		memset((void __force *)addr, 0, size);
112}
113
114/**
115 * memcpy_to_pmem - copy data to persistent memory
116 * @dst: destination buffer for the copy
117 * @src: source buffer for the copy
118 * @n: length of the copy in bytes
119 *
120 * Perform a memory copy that results in the destination of the copy
121 * being effectively evicted from, or never written to, the processor
122 * cache hierarchy after the copy completes.  After memcpy_to_pmem()
123 * data may still reside in cpu or platform buffers, so this operation
124 * must be followed by a wmb_pmem().
125 */
126static inline void memcpy_to_pmem(void __pmem *dst, const void *src, size_t n)
127{
128	if (arch_has_pmem_api())
129		arch_memcpy_to_pmem(dst, src, n);
130	else
131		default_memcpy_to_pmem(dst, src, n);
132}
133
134/**
135 * wmb_pmem - synchronize writes to persistent memory
136 *
137 * After a series of memcpy_to_pmem() operations this drains data from
138 * cpu write buffers and any platform (memory controller) buffers to
139 * ensure that written data is durable on persistent memory media.
140 */
141static inline void wmb_pmem(void)
142{
143	if (arch_has_wmb_pmem())
144		arch_wmb_pmem();
145	else
146		wmb();
147}
148
149/**
150 * copy_from_iter_pmem - copy data from an iterator to PMEM
151 * @addr:	PMEM destination address
152 * @bytes:	number of bytes to copy
153 * @i:		iterator with source data
154 *
155 * Copy data from the iterator 'i' to the PMEM buffer starting at 'addr'.
156 * This function requires explicit ordering with a wmb_pmem() call.
157 */
158static inline size_t copy_from_iter_pmem(void __pmem *addr, size_t bytes,
159		struct iov_iter *i)
160{
161	if (arch_has_pmem_api())
162		return arch_copy_from_iter_pmem(addr, bytes, i);
163	return default_copy_from_iter_pmem(addr, bytes, i);
164}
165
166/**
167 * clear_pmem - zero a PMEM memory range
168 * @addr:	virtual start address
169 * @size:	number of bytes to zero
170 *
171 * Write zeros into the memory range starting at 'addr' for 'size' bytes.
172 * This function requires explicit ordering with a wmb_pmem() call.
173 */
174static inline void clear_pmem(void __pmem *addr, size_t size)
175{
176	if (arch_has_pmem_api())
177		arch_clear_pmem(addr, size);
178	else
179		default_clear_pmem(addr, size);
180}
181#endif /* __PMEM_H__ */
182