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/*
* Copyright(c) 2015 Intel Corporation. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of version 2 of the GNU General Public License as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*/
#ifndef __PMEM_H__
#define __PMEM_H__
#include <linux/io.h>
#include <linux/uio.h>
#ifdef CONFIG_ARCH_HAS_PMEM_API
#define ARCH_MEMREMAP_PMEM MEMREMAP_WB
#include <asm/pmem.h>
#else
#define ARCH_MEMREMAP_PMEM MEMREMAP_WT
/*
* These are simply here to enable compilation, all call sites gate
* calling these symbols with arch_has_pmem_api() and redirect to the
* implementation in asm/pmem.h.
*/
static inline bool __arch_has_wmb_pmem(void)
{
return false;
}
static inline void arch_wmb_pmem(void)
{
BUG();
}
static inline void arch_memcpy_to_pmem(void __pmem *dst, const void *src,
size_t n)
{
BUG();
}
static inline size_t arch_copy_from_iter_pmem(void __pmem *addr, size_t bytes,
struct iov_iter *i)
{
BUG();
return 0;
}
static inline void arch_clear_pmem(void __pmem *addr, size_t size)
{
BUG();
}
#endif
/*
* Architectures that define ARCH_HAS_PMEM_API must provide
* implementations for arch_memcpy_to_pmem(), arch_wmb_pmem(),
* arch_copy_from_iter_pmem(), arch_clear_pmem() and arch_has_wmb_pmem().
*/
static inline void memcpy_from_pmem(void *dst, void __pmem const *src, size_t size)
{
memcpy(dst, (void __force const *) src, size);
}
static inline bool arch_has_pmem_api(void)
{
return IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API);
}
/**
* arch_has_wmb_pmem - true if wmb_pmem() ensures durability
*
* For a given cpu implementation within an architecture it is possible
* that wmb_pmem() resolves to a nop. In the case this returns
* false, pmem api users are unable to ensure durability and may want to
* fall back to a different data consistency model, or otherwise notify
* the user.
*/
static inline bool arch_has_wmb_pmem(void)
{
return arch_has_pmem_api() && __arch_has_wmb_pmem();
}
/*
* These defaults seek to offer decent performance and minimize the
* window between i/o completion and writes being durable on media.
* However, it is undefined / architecture specific whether
* ARCH_MEMREMAP_PMEM + default_memcpy_to_pmem is sufficient for
* making data durable relative to i/o completion.
*/
static inline void default_memcpy_to_pmem(void __pmem *dst, const void *src,
size_t size)
{
memcpy((void __force *) dst, src, size);
}
static inline size_t default_copy_from_iter_pmem(void __pmem *addr,
size_t bytes, struct iov_iter *i)
{
return copy_from_iter_nocache((void __force *)addr, bytes, i);
}
static inline void default_clear_pmem(void __pmem *addr, size_t size)
{
if (size == PAGE_SIZE && ((unsigned long)addr & ~PAGE_MASK) == 0)
clear_page((void __force *)addr);
else
memset((void __force *)addr, 0, size);
}
/**
* memcpy_to_pmem - copy data to persistent memory
* @dst: destination buffer for the copy
* @src: source buffer for the copy
* @n: length of the copy in bytes
*
* Perform a memory copy that results in the destination of the copy
* being effectively evicted from, or never written to, the processor
* cache hierarchy after the copy completes. After memcpy_to_pmem()
* data may still reside in cpu or platform buffers, so this operation
* must be followed by a wmb_pmem().
*/
static inline void memcpy_to_pmem(void __pmem *dst, const void *src, size_t n)
{
if (arch_has_pmem_api())
arch_memcpy_to_pmem(dst, src, n);
else
default_memcpy_to_pmem(dst, src, n);
}
/**
* wmb_pmem - synchronize writes to persistent memory
*
* After a series of memcpy_to_pmem() operations this drains data from
* cpu write buffers and any platform (memory controller) buffers to
* ensure that written data is durable on persistent memory media.
*/
static inline void wmb_pmem(void)
{
if (arch_has_wmb_pmem())
arch_wmb_pmem();
else
wmb();
}
/**
* copy_from_iter_pmem - copy data from an iterator to PMEM
* @addr: PMEM destination address
* @bytes: number of bytes to copy
* @i: iterator with source data
*
* Copy data from the iterator 'i' to the PMEM buffer starting at 'addr'.
* This function requires explicit ordering with a wmb_pmem() call.
*/
static inline size_t copy_from_iter_pmem(void __pmem *addr, size_t bytes,
struct iov_iter *i)
{
if (arch_has_pmem_api())
return arch_copy_from_iter_pmem(addr, bytes, i);
return default_copy_from_iter_pmem(addr, bytes, i);
}
/**
* clear_pmem - zero a PMEM memory range
* @addr: virtual start address
* @size: number of bytes to zero
*
* Write zeros into the memory range starting at 'addr' for 'size' bytes.
* This function requires explicit ordering with a wmb_pmem() call.
*/
static inline void clear_pmem(void __pmem *addr, size_t size)
{
if (arch_has_pmem_api())
arch_clear_pmem(addr, size);
else
default_clear_pmem(addr, size);
}
#endif /* __PMEM_H__ */
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