1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * SCSI library functions depending on DMA
4  */
5 
6 #include <linux/blkdev.h>
7 #include <linux/device.h>
8 #include <linux/export.h>
9 #include <linux/kernel.h>
10 
11 #include <scsi/scsi.h>
12 #include <scsi/scsi_cmnd.h>
13 #include <scsi/scsi_device.h>
14 #include <scsi/scsi_host.h>
15 
16 /**
17  * scsi_dma_map - perform DMA mapping against command's sg lists
18  * @cmd:	scsi command
19  *
20  * Returns the number of sg lists actually used, zero if the sg lists
21  * is NULL, or -ENOMEM if the mapping failed.
22  */
scsi_dma_map(struct scsi_cmnd * cmd)23 int scsi_dma_map(struct scsi_cmnd *cmd)
24 {
25 	int nseg = 0;
26 
27 	if (scsi_sg_count(cmd)) {
28 		struct device *dev = cmd->device->host->dma_dev;
29 
30 		nseg = dma_map_sg(dev, scsi_sglist(cmd), scsi_sg_count(cmd),
31 				  cmd->sc_data_direction);
32 		if (unlikely(!nseg))
33 			return -ENOMEM;
34 	}
35 	return nseg;
36 }
37 EXPORT_SYMBOL(scsi_dma_map);
38 
39 /**
40  * scsi_dma_unmap - unmap command's sg lists mapped by scsi_dma_map
41  * @cmd:	scsi command
42  */
scsi_dma_unmap(struct scsi_cmnd * cmd)43 void scsi_dma_unmap(struct scsi_cmnd *cmd)
44 {
45 	if (scsi_sg_count(cmd)) {
46 		struct device *dev = cmd->device->host->dma_dev;
47 
48 		dma_unmap_sg(dev, scsi_sglist(cmd), scsi_sg_count(cmd),
49 			     cmd->sc_data_direction);
50 	}
51 }
52 EXPORT_SYMBOL(scsi_dma_unmap);
53