CONFIG_SOC_TX4939 is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

CONFIG_SOC_TX4939 (not configurable)

modulename: setup_tx4939.ko

and/or

pci-tx4939.ko

configname: CONFIG_SOC_TX4939

Linux Kernel Configuration
└─>SOC_TX4939
In linux kernel since version 2.6.28 (release Date: 2008-12-24)  
source code:
/arch/mips/txx9/generic/

is selected by
CONFIG_BLK_DEV_IDE_TX4939

is depended by
CONFIG_TOSHIBA_RBTX4939