Samsung S3C2440A - Manual (Page 265)

S3C2440A RISC MICROPROCESSOR I/O PORTS
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GPGDAT Bit Description
GPG[15:0] [15:0] When the port is configured as an input port, the corresponding bit is the pin state.
When the port is configured as an output port, the pin state is the same as the
corresponding bit.
When the port is configured as functional pin, the undefined value will be read.
GPGUP Bit Description
GPG[15:0] [15:0] 0: the pull up function attached to to the corresponding port pin is enabled.
1: the pull up function is disabled.