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b842f8c639
The fake "comedi_test" device currently has two subdevices: an analog input subdevice, and an analog output subdevice. To make it a bit more useful for testing, add a third subdevice for digital I/O. The new DIO subdevice has 32 channels with each channel individually programmable as an input or an output. To add a bit of interaction, channels 0 to 15 are wired to channels 16 to 31 (0 to 16, 1 to 17, etc.), and the state of each wire can be read back on both of the channels connected to it. The outputs are modelled as NPN open collector outputs with a pull-up resistor on the wire, so the state of each wire (and the value read back from each channel connected to it) will be logic level 1 unless either channel is configured as an output at logic level 0. Signed-off-by: Ian Abbott <abbotti@mev.co.uk> Link: https://patch.msgid.link/20251210124455.69131-1-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>