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authorFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>2007-05-26 14:04:03 +0900
committerJames Bottomley <jejb@mulgrave.il.steeleye.com>2007-05-26 16:29:59 -0500
commit824d7b570b4dec49e868c251d670941b02a1e489 (patch)
tree1590c87323c9f9235945ba03627fd1ce0b731a1f /drivers/scsi
parent9ef3e4a4527e1f65b8776287c6d4fd1fca5ba98f (diff)
[SCSI] scsi_lib: add scatter/gather data buffer accessors
This adds a set of accessors for the scsi data buffer. This is in preparation for chaining sg lists and bidirectional requests (and possibly, the mid-layer dma mapping). Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Diffstat (limited to 'drivers/scsi')
-rw-r--r--drivers/scsi/scsi_lib.c38
1 files changed, 38 insertions, 0 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 1f5a07bf2a7..70454b4e848 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -2290,3 +2290,41 @@ void scsi_kunmap_atomic_sg(void *virt)
kunmap_atomic(virt, KM_BIO_SRC_IRQ);
}
EXPORT_SYMBOL(scsi_kunmap_atomic_sg);
+
+/**
+ * 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->shost_gendev.parent;
+
+ 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->shost_gendev.parent;
+
+ dma_unmap_sg(dev, scsi_sglist(cmd), scsi_sg_count(cmd),
+ cmd->sc_data_direction);
+ }
+}
+EXPORT_SYMBOL(scsi_dma_unmap);