The EP93xx has four chip selects that can be used for the SDRAM memory.
These chip selects are decoded to specify an address domain:
SDCS3 0x00000000-0x0fffffff with Boot Option ASDO=1
SDCS0 0xc0000000-0xcfffffff
SDCS1 0xd0000000-0xdfffffff
SDCS2 0xe0000000-x0efffffff
SDCS3 0xf0000000-0xffffffff with Boot Option ASDO=0
Because of the row/column/bank architecture of SDRAM, the mapping of
these memories into the processor's memory space is discontiguous.
Most ep93xx systems only use one of the chip selects. For these systems,
ARCH_HAS_HOLES_MEMORYMODEL has worked fine to handle the discontiguous
memory.
But, some of the TS-72xx boards use multiple chip selects. The TS-7300 in
particular uses SDCS3 (with ASDO=1) and SDCS2. On that system with
ARCH_HAS_HOLES_MEMORYMODEL the SDCS2 memory does not get handled correctly
and results in the system not booting.
Change the EP93xx to ARCH_SPARSEMEM_ENABLE. This handles the discontiguous
memory for all configurations.
This has been tested on the following ep93xx platforms:
EDB9307A with 64 MiB on SDCS0
Vision EP9307 with 64 MiB on SDCS0
TS-7300 with 64 MiB on SDCS3 (with ASDO=1) and 64 MiB on SDCS2
sim.one with 64 MiB on SDCS0
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Cc: Russell King <linux@armlinux.org.uk>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>