include/linux/pmem.h

   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  */
  29 static inline bool __arch_has_wmb_pmem(void)
  30 {
  31         return false;
  32 }
  33
  34 static inline void arch_wmb_pmem(void)
  35 {
  36         BUG();
  37 }
  38
  39 static inline void arch_memcpy_to_pmem(void __pmem *dst, const void *src,
  40                 size_t n)
  41 {
  42         BUG();
  43 }
  44
  45 static 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
  52 static 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  */
  63 static 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
  68 static 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  */
  82 static 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  */
  94 static 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
 100 static 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
 106 static 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  */
 126 static 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  */
 141 static 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  */
 158 static 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  */
 174 static 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__ */