comedi: das16: Add sanity checks for I/O base address

The "das16" driver uses an admin-supplied configuration option
(`it->options[0]`) to configure the I/O port base address of a various
DAS16 compatible boards.  It currently allows any base address to be
configured but the hardware only supports base addresses (configured by
an on-board DIP switch) in the range 0 to 0x3f0 on 16- or 32-byte
boundaries.  Some of the boards have an 8255 chip at offset 0x10 and
require the board to be configured on a 32-byte boundary unless some
on-board jumpers are set to limit the board to decoding only the first
0x10 registers, disabling access to the 8255.  Some other boards place
the 8255 chip (and some other registers) at offset 0x400 from the base
address, decoding 0x10 registers at the base address and 0x8 registers
at the base address plus 0x400.

Add a sanity check to ensure the device is not configured at an
unsupported base address.  If the device has the 8255 chip at offset
0x10, and is being configured with the base address at an odd 16-byte
boundary, limit the size of the region to 0x10 and disable the 8255
subdevice.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://patch.msgid.link/20260130170416.49994-14-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

0 files changed, 0 insertions, 0 deletions