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83d290c56f
When U-Boot started using SPDX tags we were among the early adopters and there weren't a lot of other examples to borrow from. So we picked the area of the file that usually had a full license text and replaced it with an appropriate SPDX-License-Identifier: entry. Since then, the Linux Kernel has adopted SPDX tags and they place it as the very first line in a file (except where shebangs are used, then it's second line) and with slightly different comment styles than us. In part due to community overlap, in part due to better tag visibility and in part for other minor reasons, switch over to that style. This commit changes all instances where we have a single declared license in the tag as both the before and after are identical in tag contents. There's also a few places where I found we did not have a tag and have introduced one. Signed-off-by: Tom Rini <trini@konsulko.com>
116 lines
4.3 KiB
C
116 lines
4.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0+ */
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/*
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* Copyright (c) 2015 Google, Inc
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*/
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#ifndef __ALIGNMEM_H
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#define __ALIGNMEM_H
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/*
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* ARCH_DMA_MINALIGN is defined in asm/cache.h for each architecture. It
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* is used to align DMA buffers.
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*/
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#ifndef __ASSEMBLY__
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#include <asm/cache.h>
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#include <malloc.h>
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/*
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* The ALLOC_CACHE_ALIGN_BUFFER macro is used to allocate a buffer on the
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* stack that meets the minimum architecture alignment requirements for DMA.
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* Such a buffer is useful for DMA operations where flushing and invalidating
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* the cache before and after a read and/or write operation is required for
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* correct operations.
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*
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* When called the macro creates an array on the stack that is sized such
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* that:
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*
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* 1) The beginning of the array can be advanced enough to be aligned.
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*
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* 2) The size of the aligned portion of the array is a multiple of the minimum
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* architecture alignment required for DMA.
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*
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* 3) The aligned portion contains enough space for the original number of
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* elements requested.
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*
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* The macro then creates a pointer to the aligned portion of this array and
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* assigns to the pointer the address of the first element in the aligned
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* portion of the array.
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*
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* Calling the macro as:
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*
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* ALLOC_CACHE_ALIGN_BUFFER(uint32_t, buffer, 1024);
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*
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* Will result in something similar to saying:
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*
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* uint32_t buffer[1024];
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*
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* The following differences exist:
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*
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* 1) The resulting buffer is guaranteed to be aligned to the value of
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* ARCH_DMA_MINALIGN.
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*
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* 2) The buffer variable created by the macro is a pointer to the specified
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* type, and NOT an array of the specified type. This can be very important
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* if you want the address of the buffer, which you probably do, to pass it
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* to the DMA hardware. The value of &buffer is different in the two cases.
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* In the macro case it will be the address of the pointer, not the address
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* of the space reserved for the buffer. However, in the second case it
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* would be the address of the buffer. So if you are replacing hard coded
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* stack buffers with this macro you need to make sure you remove the & from
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* the locations where you are taking the address of the buffer.
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*
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* Note that the size parameter is the number of array elements to allocate,
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* not the number of bytes.
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*
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* This macro can not be used outside of function scope, or for the creation
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* of a function scoped static buffer. It can not be used to create a cache
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* line aligned global buffer.
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*/
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#define PAD_COUNT(s, pad) (((s) - 1) / (pad) + 1)
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#define PAD_SIZE(s, pad) (PAD_COUNT(s, pad) * pad)
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#define ALLOC_ALIGN_BUFFER_PAD(type, name, size, align, pad) \
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char __##name[ROUND(PAD_SIZE((size) * sizeof(type), pad), align) \
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+ (align - 1)]; \
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\
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type *name = (type *)ALIGN((uintptr_t)__##name, align)
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#define ALLOC_ALIGN_BUFFER(type, name, size, align) \
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ALLOC_ALIGN_BUFFER_PAD(type, name, size, align, 1)
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#define ALLOC_CACHE_ALIGN_BUFFER_PAD(type, name, size, pad) \
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ALLOC_ALIGN_BUFFER_PAD(type, name, size, ARCH_DMA_MINALIGN, pad)
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#define ALLOC_CACHE_ALIGN_BUFFER(type, name, size) \
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ALLOC_ALIGN_BUFFER(type, name, size, ARCH_DMA_MINALIGN)
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/*
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* DEFINE_CACHE_ALIGN_BUFFER() is similar to ALLOC_CACHE_ALIGN_BUFFER, but it's
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* purpose is to allow allocating aligned buffers outside of function scope.
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* Usage of this macro shall be avoided or used with extreme care!
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*/
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#define DEFINE_ALIGN_BUFFER(type, name, size, align) \
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static char __##name[ALIGN(size * sizeof(type), align)] \
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__aligned(align); \
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\
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static type *name = (type *)__##name
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#define DEFINE_CACHE_ALIGN_BUFFER(type, name, size) \
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DEFINE_ALIGN_BUFFER(type, name, size, ARCH_DMA_MINALIGN)
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/**
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* malloc_cache_aligned() - allocate a memory region aligned to cache line size
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*
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* This allocates memory at a cache-line boundary. The amount allocated may
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* be larger than requested as it is rounded up to the nearest multiple of the
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* cache-line size. This ensured that subsequent cache operations on this
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* memory (flush, invalidate) will not affect subsequently allocated regions.
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*
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* @size: Minimum number of bytes to allocate
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*
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* @return pointer to new memory region, or NULL if there is no more memory
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* available.
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*/
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static inline void *malloc_cache_aligned(size_t size)
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{
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return memalign(ARCH_DMA_MINALIGN, ALIGN(size, ARCH_DMA_MINALIGN));
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}
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#endif
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#endif /* __ALIGNMEM_H */
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