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
  57 static inline void arch_wb_cache_pmem(void __pmem *addr, size_t size)
  58 {
  59         BUG();
  60 }
  61 #endif
  62
  63 /*
  64  * Architectures that define ARCH_HAS_PMEM_API must provide
  65  * implementations for arch_memcpy_to_pmem(), arch_wmb_pmem(),
  66  * arch_copy_from_iter_pmem(), arch_clear_pmem(), arch_wb_cache_pmem()
  67  * and arch_has_wmb_pmem().
  68  */
  69 static inline void memcpy_from_pmem(void *dst, void __pmem const *src, size_t size)
  70 {
  71         memcpy(dst, (void __force const *) src, size);
  72 }
  73
  74 static inline bool arch_has_pmem_api(void)
  75 {
  76         return IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API);
  77 }
  78
  79 /**
  80  * arch_has_wmb_pmem - true if wmb_pmem() ensures durability
  81  *
  82  * For a given cpu implementation within an architecture it is possible
  83  * that wmb_pmem() resolves to a nop.  In the case this returns
  84  * false, pmem api users are unable to ensure durability and may want to
  85  * fall back to a different data consistency model, or otherwise notify
  86  * the user.
  87  */
  88 static inline bool arch_has_wmb_pmem(void)
  89 {
  90         return arch_has_pmem_api() && __arch_has_wmb_pmem();
  91 }
  92
  93 /*
  94  * These defaults seek to offer decent performance and minimize the
  95  * window between i/o completion and writes being durable on media.
  96  * However, it is undefined / architecture specific whether
  97  * ARCH_MEMREMAP_PMEM + default_memcpy_to_pmem is sufficient for
  98  * making data durable relative to i/o completion.
  99  */
 100 static inline void default_memcpy_to_pmem(void __pmem *dst, const void *src,
 101                 size_t size)
 102 {
 103         memcpy((void __force *) dst, src, size);
 104 }
 105
 106 static inline size_t default_copy_from_iter_pmem(void __pmem *addr,
 107                 size_t bytes, struct iov_iter *i)
 108 {
 109         return copy_from_iter_nocache((void __force *)addr, bytes, i);
 110 }
 111
 112 static inline void default_clear_pmem(void __pmem *addr, size_t size)
 113 {
 114         if (size == PAGE_SIZE && ((unsigned long)addr & ~PAGE_MASK) == 0)
 115                 clear_page((void __force *)addr);
 116         else
 117                 memset((void __force *)addr, 0, 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  */
 132 static 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  */
 147 static inline void wmb_pmem(void)
 148 {
 149         if (arch_has_wmb_pmem())
 150                 arch_wmb_pmem();
 151         else
 152                 wmb();
 153 }
 154
 155 /**
 156  * copy_from_iter_pmem - copy data from an iterator to PMEM
 157  * @addr:       PMEM destination address
 158  * @bytes:      number of bytes to copy
 159  * @i:          iterator with source data
 160  *
 161  * Copy data from the iterator 'i' to the PMEM buffer starting at 'addr'.
 162  * This function requires explicit ordering with a wmb_pmem() call.
 163  */
 164 static inline size_t copy_from_iter_pmem(void __pmem *addr, size_t bytes,
 165                 struct iov_iter *i)
 166 {
 167         if (arch_has_pmem_api())
 168                 return arch_copy_from_iter_pmem(addr, bytes, i);
 169         return default_copy_from_iter_pmem(addr, bytes, i);
 170 }
 171
 172 /**
 173  * clear_pmem - zero a PMEM memory range
 174  * @addr:       virtual start address
 175  * @size:       number of bytes to zero
 176  *
 177  * Write zeros into the memory range starting at 'addr' for 'size' bytes.
 178  * This function requires explicit ordering with a wmb_pmem() call.
 179  */
 180 static inline void clear_pmem(void __pmem *addr, size_t size)
 181 {
 182         if (arch_has_pmem_api())
 183                 arch_clear_pmem(addr, size);
 184         else
 185                 default_clear_pmem(addr, size);
 186 }
 187
 188 /**
 189  * wb_cache_pmem - write back processor cache for PMEM memory range
 190  * @addr:       virtual start address
 191  * @size:       number of bytes to write back
 192  *
 193  * Write back the processor cache range starting at 'addr' for 'size' bytes.
 194  * This function requires explicit ordering with a wmb_pmem() call.
 195  */
 196 static inline void wb_cache_pmem(void __pmem *addr, size_t size)
 197 {
 198         if (arch_has_pmem_api())
 199                 arch_wb_cache_pmem(addr, size);
 200 }
 201 #endif /* __PMEM_H__ */