[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>

4 files changed, 58 insertions, 41 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
diff --git a/drivers/scsi/Makefile b/drivers/scsi/Makefile
index cbc2e2ba5412..0f8689557158 100644
--- a/drivers/scsi/Makefile
+++ b/drivers/scsi/Makefile
@@ -148,9 +148,9 @@ obj-$(CONFIG_SCSI_DEBUG)	+= scsi_debug.o
 obj-$(CONFIG_SCSI_WAIT_SCAN)    += scsi_wait_scan.o
 
 scsi_mod-y                      += scsi.o hosts.o scsi_ioctl.o constants.o \
-                                   scsicam.o scsi_error.o scsi_lib.o \
-                                   scsi_scan.o scsi_sysfs.o \
-                                   scsi_devinfo.o
+                                   scsicam.o scsi_error.o scsi_lib.o
+scsi_mod-$(CONFIG_SCSI_DMA)     += scsi_lib_dma.o
+scsi_mod-y                      += scsi_scan.o scsi_sysfs.o scsi_devinfo.o
 scsi_mod-$(CONFIG_SCSI_NETLINK) += scsi_netlink.o
 scsi_mod-$(CONFIG_SYSCTL)       += scsi_sysctl.o
 scsi_mod-$(CONFIG_SCSI_PROC_FS) += scsi_proc.o
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 70454b4e8485..1f5a07bf2a75 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -2290,41 +2290,3 @@ 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);
diff --git a/drivers/scsi/scsi_lib_dma.c b/drivers/scsi/scsi_lib_dma.c
new file mode 100644
index 000000000000..ac6855cd2657
--- /dev/null
+++ b/drivers/scsi/scsi_lib_dma.c
@@ -0,0 +1,50 @@
+/*
+ * SCSI library functions depending on DMA
+ */
+
+#include <linux/blkdev.h>
+#include <linux/device.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->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);