1 files changed, 52 insertions, 0 deletions
diff --git a/drivers/scsi/scsi_lib_dma.c b/drivers/scsi/scsi_lib_dma.c
new file mode 100644
index 000000000..572391527
--- /dev/null
+++ b/drivers/scsi/scsi_lib_dma.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * SCSI library functions depending on DMA
+ */
+
+#include <linux/blkdev.h>
+#include <linux/device.h>
+#include <linux/export.h>
+#include <linux/kernel.h>
+
+#include <scsi/scsi.h>
+#include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_host.h>
+
+/**
+ * scsi_dma_map - perform DMA mapping against command's sg lists
+ * @cmd:	scsi command
+ *
+ * Returns the number of sg lists actually used, zero if the sg lists
+ * is NULL, or -ENOMEM if the mapping failed.
+ */
+int scsi_dma_map(struct scsi_cmnd *cmd)
+{
+	int nseg = 0;
+
+	if (scsi_sg_count(cmd)) {
+		struct device *dev = cmd->device->host->dma_dev;
+
+		nseg = dma_map_sg(dev, scsi_sglist(cmd), scsi_sg_count(cmd),
+				  cmd->sc_data_direction);
+		if (unlikely(!nseg))
+			return -ENOMEM;
+	}
+	return nseg;
+}
+EXPORT_SYMBOL(scsi_dma_map);
+
+/**
+ * scsi_dma_unmap - unmap command's sg lists mapped by scsi_dma_map
+ * @cmd:	scsi command
+ */
+void scsi_dma_unmap(struct scsi_cmnd *cmd)
+{
+	if (scsi_sg_count(cmd)) {
+		struct device *dev = cmd->device->host->dma_dev;
+
+		dma_unmap_sg(dev, scsi_sglist(cmd), scsi_sg_count(cmd),
+			     cmd->sc_data_direction);
+	}
+}
+EXPORT_SYMBOL(scsi_dma_unmap);