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#ifndef __LINUX_CMA_H
#define __LINUX_CMA_H
/*
* Contiguous Memory Allocator for DMA mapping framework
* Copyright (c) 2010-2011 by Samsung Electronics.
* Written by:
* Marek Szyprowski <m.szyprowski@samsung.com>
* Michal Nazarewicz <mina86@mina86.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License or (at your optional) any later version of the license.
*/
/*
* Contiguous Memory Allocator
*
* The Contiguous Memory Allocator (CMA) makes it possible to
* allocate big contiguous chunks of memory after the system has
* booted.
*
* Why is it needed?
*
* Various devices on embedded systems have no scatter-getter and/or
* IO map support and require contiguous blocks of memory to
* operate. They include devices such as cameras, hardware video
* coders, etc.
*
* Such devices often require big memory buffers (a full HD frame
* is, for instance, more then 2 mega pixels large, i.e. more than 6
* MB of memory), which makes mechanisms such as kmalloc() or
* alloc_page() ineffective.
*
* At the same time, a solution where a big memory region is
* reserved for a device is suboptimal since often more memory is
* reserved then strictly required and, moreover, the memory is
* inaccessible to page system even if device drivers don't use it.
*
* CMA tries to solve this issue by operating on memory regions
* where only movable pages can be allocated from. This way, kernel
* can use the memory for pagecache and when device driver requests
* it, allocated pages can be migrated.
*
* Driver usage
*
* CMA should not be used by the device drivers directly. It is
* only a helper framework for dma-mapping subsystem.
*
* For more information, see kernel-docs in drivers/base/dma-contiguous.c
*/
#ifdef __KERNEL__
struct cma;
struct page;
struct device;
#ifdef CONFIG_CMA
/*
* There is always at least global CMA area and a few optional device
* private areas configured in kernel .config.
*/
#define MAX_CMA_AREAS (1 + CONFIG_CMA_AREAS)
extern struct cma *dma_contiguous_default_area;
void dma_contiguous_reserve(phys_addr_t addr_limit);
int dma_declare_contiguous(struct device *dev, phys_addr_t size,
phys_addr_t base, phys_addr_t limit);
struct page *dma_alloc_from_contiguous(struct device *dev, int count,
unsigned int order);
bool dma_release_from_contiguous(struct device *dev, struct page *pages,
int count);
#else
#define MAX_CMA_AREAS (0)
static inline void dma_contiguous_reserve(phys_addr_t limit) { }
static inline
int dma_declare_contiguous(struct device *dev, phys_addr_t size,
phys_addr_t base, phys_addr_t limit)
{
return -ENOSYS;
}
static inline
struct page *dma_alloc_from_contiguous(struct device *dev, int count,
unsigned int order)
{
return NULL;
}
static inline
bool dma_release_from_contiguous(struct device *dev, struct page *pages,
int count)
{
return false;
}
#endif
#endif
#endif
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