drivers/scsi/scsi_lib_dma.c

   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  */
  22 int 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 }
  36 EXPORT_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  */
  42 void 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 }
  51 EXPORT_SYMBOL(scsi_dma_unmap);