CONFIG_GPIO_TXX9 is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

CONFIG_GPIO_TXX9 (not configurable)

modulename: gpio_txx9.ko

configname: CONFIG_GPIO_TXX9

Linux Kernel Configuration
└─>GPIO_TXX9
In linux kernel since version 2.6.26 (release Date: 2008-07-13)  
source code:
arch/mips/kernel/gpio_txx9.c
selects
CONFIG_GPIOLIB