[SCSI] don't build scsi_dma_{map,unmap} for !HAS_DMA

With

 dma-mapping-prevent-dma-dependent-code-from-linking-on.patch

scsi fails to build on !HAS_DMA architectures:

drivers/built-in.o(.text+0x20af6): In function `scsi_dma_map':
: undefined reference to `dma_map_sg'
drivers/built-in.o(.text+0x20b5c): In function `scsi_dma_unmap':
: undefined reference to `dma_unmap_sg'

I split those functions out into a new file. Builds on s390 and i386.

Move scsi_dma_{map,unmap} into scsi_lib_dma.c which is only build if
HAS_DMA is set.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: James Bottomley <James.Bottomley@SteelEye.com>
Cc: Jeff Garzik <jeff@garzik.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/scsi/Kconfig b/drivers/scsi/Kconfig
index 874cfee29358..6ac3873e4d73 100644
--- a/drivers/scsi/Kconfig
+++ b/drivers/scsi/Kconfig
@@ -10,6 +10,7 @@ config RAID_ATTRS
 config SCSI
         tristate "SCSI device support"
         depends on BLOCK
+        select SCSI_DMA if HAS_DMA
         ---help---
           If you want to use a SCSI hard disk, SCSI tape drive, SCSI CD-ROM or
           any other SCSI device under Linux, say Y and make sure that you know
@@ -29,6 +30,10 @@ config SCSI
           However, do not compile this as a module if your root file system
           (the one containing the directory /) is located on a SCSI device.
 
+config SCSI_DMA
+        bool
+        default n
+
 config SCSI_TGT
         tristate "SCSI target support"
         depends on SCSI && EXPERIMENTAL