linux/drivers/scsi/scsi_lib_dma.c
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   1/*
   2 * SCSI library functions depending on DMA
   3 */
   4
   5#include <linux/blkdev.h>
   6#include <linux/device.h>
   7#include <linux/export.h>
   8#include <linux/kernel.h>
   9
  10#include <scsi/scsi.h>
  11#include <scsi/scsi_cmnd.h>
  12#include <scsi/scsi_device.h>
  13#include <scsi/scsi_host.h>
  14
  15/**
  16 * scsi_dma_map - perform DMA mapping against command's sg lists
  17 * @cmd:        scsi command
  18 *
  19 * Returns the number of sg lists actually used, zero if the sg lists
  20 * is NULL, or -ENOMEM if the mapping failed.
  21 */
  22int scsi_dma_map(struct scsi_cmnd *cmd)
  23{
  24        int nseg = 0;
  25
  26        if (scsi_sg_count(cmd)) {
  27                struct device *dev = cmd->device->host->dma_dev;
  28
  29                nseg = dma_map_sg(dev, scsi_sglist(cmd), scsi_sg_count(cmd),
  30                                  cmd->sc_data_direction);
  31                if (unlikely(!nseg))
  32                        return -ENOMEM;
  33        }
  34        return nseg;
  35}
  36EXPORT_SYMBOL(scsi_dma_map);
  37
  38/**
  39 * scsi_dma_unmap - unmap command's sg lists mapped by scsi_dma_map
  40 * @cmd:        scsi command
  41 */
  42void scsi_dma_unmap(struct scsi_cmnd *cmd)
  43{
  44        if (scsi_sg_count(cmd)) {
  45                struct device *dev = cmd->device->host->dma_dev;
  46
  47                dma_unmap_sg(dev, scsi_sglist(cmd), scsi_sg_count(cmd),
  48                             cmd->sc_data_direction);
  49        }
  50}
  51EXPORT_SYMBOL(scsi_dma_unmap);
  52
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