include/linux/dma-mapping.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_DMA_MAPPING_H
   3 #define _LINUX_DMA_MAPPING_H
   4
   5 #include <asm/cache.h>
   6 #include <linux/dma-direction.h>
   7 #include <linux/types.h>
   8 #include <asm/dma-mapping.h>
   9 #include <cpu_func.h>
  10
  11 #define dma_mapping_error(x, y) 0
  12
  13 /**
  14  * Map a buffer to make it available to the DMA device
  15  *
  16  * Linux-like DMA API that is intended to be used from drivers. This hides the
  17  * underlying cache operation from drivers. Call this before starting the DMA
  18  * transfer. In most of architectures in U-Boot, the virtual address matches to
  19  * the physical address (but we have exceptions like sandbox). U-Boot does not
  20  * support iommu at the driver level, so it also matches to the DMA address.
  21  * Hence, this helper currently just performs the cache operation, then returns
  22  * straight-mapped dma_address, which is intended to be set to the register of
  23  * the DMA device.
  24  *
  25  * @vaddr: address of the buffer
  26  * @len: length of the buffer
  27  * @dir: the direction of DMA
  28  */
  29 static inline dma_addr_t dma_map_single(void *vaddr, size_t len,
  30                                         enum dma_data_direction dir)
  31 {
  32         unsigned long addr = (unsigned long)vaddr;
  33
  34         len = ALIGN(len, ARCH_DMA_MINALIGN);
  35
  36         if (dir == DMA_FROM_DEVICE)
  37                 invalidate_dcache_range(addr, addr + len);
  38         else
  39                 flush_dcache_range(addr, addr + len);
  40
  41         return addr;
  42 }
  43
  44 /**
  45  * Unmap a buffer to make it available to CPU
  46  *
  47  * Linux-like DMA API that is intended to be used from drivers. This hides the
  48  * underlying cache operation from drivers. Call this after finishin the DMA
  49  * transfer.
  50  *
  51  * @addr: DMA address
  52  * @len: length of the buffer
  53  * @dir: the direction of DMA
  54  */
  55 static inline void dma_unmap_single(dma_addr_t addr, size_t len,
  56                                     enum dma_data_direction dir)
  57 {
  58         len = ALIGN(len, ARCH_DMA_MINALIGN);
  59
  60         if (dir != DMA_TO_DEVICE)
  61                 invalidate_dcache_range(addr, addr + len);
  62 }
  63
  64 #endif