// 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);