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dma-mapping: move dma_map_(un)single() to <linux/dma-mapping.h>

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The implementation of dma_map_single() and dma_unmap_single() is
exactly the same for all the architectures that support them.

Factor them out to <linux/dma-mapping.h>, and make all drivers to
include <linux/dma-mapping.h> instead of <asm/dma-mapping.h>.

If we need to differentiate them for some architectures, we can
move the generic definitions to <asm-generic/dma-mapping.h>.

Add some comments to the helpers. The concept is quite similar to
the DMA-API of Linux kernel. Drivers are agnostic about what is
going on behind the scene. Just call dma_map_single() before the
DMA, and dma_unmap_single() after it.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
This commit is contained in:
Masahiro Yamada
2020-02-14 16:40:19 +09:00
committed by Peng Fan
parent 950c596867
commit 9d86b89c59
17 changed files with 75 additions and 116 deletions
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63
include/linux/dma-mapping.h Normal file
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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_DMA_MAPPING_H
#define _LINUX_DMA_MAPPING_H
#include <linux/dma-direction.h>
#include <linux/types.h>
#include <asm/dma-mapping.h>
#include <cpu_func.h>
#define dma_mapping_error(x, y) 0
/**
* Map a buffer to make it available to the DMA device
*
* Linux-like DMA API that is intended to be used from drivers. This hides the
* underlying cache operation from drivers. Call this before starting the DMA
* transfer. In most of architectures in U-Boot, the virtual address matches to
* the physical address (but we have exceptions like sandbox). U-Boot does not
* support iommu at the driver level, so it also matches to the DMA address.
* Hence, this helper currently just performs the cache operation, then returns
* straight-mapped dma_address, which is intended to be set to the register of
* the DMA device.
*
* @vaddr: address of the buffer
* @len: length of the buffer
* @dir: the direction of DMA
*/
static inline dma_addr_t dma_map_single(void *vaddr, size_t len,
enum dma_data_direction dir)
{
unsigned long addr = (unsigned long)vaddr;
len = ALIGN(len, ARCH_DMA_MINALIGN);
if (dir == DMA_FROM_DEVICE)
invalidate_dcache_range(addr, addr + len);
else
flush_dcache_range(addr, addr + len);
return addr;
}
/**
* Unmap a buffer to make it available to CPU
*
* Linux-like DMA API that is intended to be used from drivers. This hides the
* underlying cache operation from drivers. Call this after finishin the DMA
* transfer.
*
* @addr: DMA address
* @len: length of the buffer
* @dir: the direction of DMA
*/
static inline void dma_unmap_single(dma_addr_t addr, size_t len,
enum dma_data_direction dir)
{
len = ALIGN(len, ARCH_DMA_MINALIGN);
if (dir != DMA_TO_DEVICE)
invalidate_dcache_range(addr, addr + len);
}
#endif