Realtek USB SD/MMC Card Interface Driver

modulename: rtsx_usb_sdmmc.ko

configname: CONFIG_MMC_REALTEK_USB

Linux Kernel Configuration
└─>Device Drivers
└─>MMC/SD/SDIO card support
└─>Realtek USB SD/MMC Card Interface Driver
In linux kernel since version 3.16 (release Date: 2014-08-03)  
Say Y here to include driver code to support SD/MMC card interface
of Realtek RTS5129/39 series card reader

source code:
drivers/mmc/host/rtsx_usb_sdmmc.c