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/* SPDX-License-Identifier: GPL-2.0-or-later */
#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>
*/
/*
* 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 kernel/dma/contiguous.c
*/
#ifdef __KERNEL__
#include <linux/device.h>
#include <linux/mm.h>
struct cma;
struct page;
#ifdef CONFIG_DMA_CMA
extern struct cma *dma_contiguous_default_area;
static inline struct cma *dev_get_cma_area(struct device *dev)
{
if (dev && dev->cma_area)
return dev->cma_area;
return dma_contiguous_default_area;
}
static inline void dev_set_cma_area(struct device *dev, struct cma *cma)
{
if (dev)
dev->cma_area = cma;
}
static inline void dma_contiguous_set_default(struct cma *cma)
{
dma_contiguous_default_area = cma;
}
void dma_contiguous_reserve(phys_addr_t addr_limit);
int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
phys_addr_t limit, struct cma **res_cma,
bool fixed);
struct page *dma_alloc_from_contiguous(struct device *dev, size_t count,
unsigned int order, bool no_warn);
bool dma_release_from_contiguous(struct device *dev, struct page *pages,
int count);
struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp);
void dma_free_contiguous(struct device *dev, struct page *page, size_t size);
#else
static inline struct cma *dev_get_cma_area(struct device *dev)
{
return NULL;
}
static inline void dev_set_cma_area(struct device *dev, struct cma *cma) { }
static inline void dma_contiguous_set_default(struct cma *cma) { }
static inline void dma_contiguous_reserve(phys_addr_t limit) { }
static inline int dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
phys_addr_t limit, struct cma **res_cma,
bool fixed)
{
return -ENOSYS;
}
static inline
struct page *dma_alloc_from_contiguous(struct device *dev, size_t count,
unsigned int order, bool no_warn)
{
return NULL;
}
static inline
bool dma_release_from_contiguous(struct device *dev, struct page *pages,
int count)
{
return false;
}
/* Use fallback alloc() and free() when CONFIG_DMA_CMA=n */
static inline struct page *dma_alloc_contiguous(struct device *dev, size_t size,
gfp_t gfp)
{
return NULL;
}
static inline void dma_free_contiguous(struct device *dev, struct page *page,
size_t size)
{
__free_pages(page, get_order(size));
}
#endif
#ifdef CONFIG_DMA_PERNUMA_CMA
void dma_pernuma_cma_reserve(void);
#else
static inline void dma_pernuma_cma_reserve(void) { }
#endif
#endif
#endif
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