forked from rubenslte/android_kernel_samsung_msm8226
Laura Abbott
2dcd9e61f7
When setting CMA up at a fixed region, it is possible for the address to be shared between multiple subsystems. If the address is placed dynamically, there is no mechanism to be able to get the start address of the region. Drivers may wish to do keep track of allocations relative to the start address so add an API to get the start region of a CMA address. Change-Id: If0730c64496c876d3143064d767b22b984c6dc84 Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
146 lines
4.0 KiB
C
146 lines
4.0 KiB
C
#ifndef __LINUX_CMA_H
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#define __LINUX_CMA_H
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/*
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* Contiguous Memory Allocator for DMA mapping framework
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* Copyright (c) 2010-2011 by Samsung Electronics.
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* Written by:
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* Marek Szyprowski <m.szyprowski@samsung.com>
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* Michal Nazarewicz <mina86@mina86.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License or (at your optional) any later version of the license.
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*/
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/*
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* Contiguous Memory Allocator
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*
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* The Contiguous Memory Allocator (CMA) makes it possible to
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* allocate big contiguous chunks of memory after the system has
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* booted.
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*
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* Why is it needed?
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*
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* Various devices on embedded systems have no scatter-getter and/or
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* IO map support and require contiguous blocks of memory to
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* operate. They include devices such as cameras, hardware video
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* coders, etc.
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*
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* Such devices often require big memory buffers (a full HD frame
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* is, for instance, more then 2 mega pixels large, i.e. more than 6
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* MB of memory), which makes mechanisms such as kmalloc() or
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* alloc_page() ineffective.
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*
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* At the same time, a solution where a big memory region is
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* reserved for a device is suboptimal since often more memory is
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* reserved then strictly required and, moreover, the memory is
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* inaccessible to page system even if device drivers don't use it.
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*
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* CMA tries to solve this issue by operating on memory regions
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* where only movable pages can be allocated from. This way, kernel
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* can use the memory for pagecache and when device driver requests
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* it, allocated pages can be migrated.
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*
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* Driver usage
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*
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* CMA should not be used by the device drivers directly. It is
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* only a helper framework for dma-mapping subsystem.
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*
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* For more information, see kernel-docs in drivers/base/dma-contiguous.c
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*/
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#ifdef __KERNEL__
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struct cma;
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struct page;
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struct device;
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#ifdef CONFIG_CMA
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/*
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* There is always at least global CMA area and a few optional device
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* private areas configured in kernel .config.
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*/
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#define MAX_CMA_AREAS (1 + CONFIG_CMA_AREAS)
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phys_addr_t cma_get_base(struct device *dev);
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extern struct cma *dma_contiguous_def_area;
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void dma_contiguous_reserve(phys_addr_t addr_limit);
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int dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t *res_base,
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phys_addr_t limit, const char *name);
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int dma_contiguous_add_device(struct device *dev, phys_addr_t base);
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/**
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* dma_declare_contiguous() - reserve area for contiguous memory handling
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* for particular device
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* @dev: Pointer to device structure.
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* @size: Size of the reserved memory.
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* @base: Start address of the reserved memory (optional, 0 for any).
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* @limit: End address of the reserved memory (optional, 0 for any).
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*
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* This function reserves memory for specified device. It should be
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* called by board specific code when early allocator (memblock or bootmem)
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* is still activate.
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*/
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static inline int dma_declare_contiguous(struct device *dev, phys_addr_t size,
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phys_addr_t base, phys_addr_t limit)
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{
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int ret;
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ret = dma_contiguous_reserve_area(size, &base, limit, NULL);
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if (ret == 0)
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ret = dma_contiguous_add_device(dev, base);
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return ret;
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}
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struct page *dma_alloc_from_contiguous(struct device *dev, int count,
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unsigned int order);
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bool dma_release_from_contiguous(struct device *dev, struct page *pages,
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int count);
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#else
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#define MAX_CMA_AREAS (0)
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static inline void dma_contiguous_reserve(phys_addr_t limit) { }
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static inline
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int dma_declare_contiguous(struct device *dev, phys_addr_t size,
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phys_addr_t base, phys_addr_t limit)
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{
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return -ENOSYS;
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}
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static inline
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struct page *dma_alloc_from_contiguous(struct device *dev, int count,
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unsigned int order)
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{
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return NULL;
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}
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static inline
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bool dma_release_from_contiguous(struct device *dev, struct page *pages,
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int count)
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{
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return false;
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}
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static inline phys_addr_t cma_get_base(struct device *dev)
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{
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return 0;
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}
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#endif
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#endif
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#endif
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