arch/*/: remove CONFIG_VIRT_TO_BUS

All architecture-independent users of virt_to_bus() and bus_to_virt()
have been fixed to use the dma mapping interfaces or have been
removed now.  This means the definitions on most architectures, and the
CONFIG_VIRT_TO_BUS symbol are now obsolete and can be removed.

The only exceptions to this are a few network and scsi drivers for m68k
Amiga and VME machines and ppc32 Macintosh. These drivers work correctly
with the old interfaces and are probably not worth changing.

On alpha and parisc, virt_to_bus() were still used in asm/floppy.h.
alpha can use isa_virt_to_bus() like x86 does, and parisc can just
open-code the virt_to_phys() here, as this is architecture specific
code.

I tried updating the bus-virt-phys-mapping.rst documentation, which
started as an email from Linus to explain some details of the Linux-2.0
driver interfaces. The bits about virt_to_bus() were declared obsolete
backin 2000, and the rest is not all that relevant any more, so in the
end I just decided to remove the file completely.

Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Acked-by: Helge Deller <deller@gmx.de> # parisc
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 0 insertions, 1 deletions

diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index 7d0d26b5b3f5..97fce7386b00 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -17,7 +17,6 @@ config ALPHA
 	select HAVE_PERF_EVENTS
 	select NEED_DMA_MAP_STATE
 	select NEED_SG_DMA_LENGTH
-	select VIRT_TO_BUS
 	select GENERIC_IRQ_PROBE
 	select GENERIC_PCI_IOMAP
 	select AUTO_IRQ_AFFINITY if SMP