AT91SAM9x

modulename: rtc-at91sam9.ko

configname: CONFIG_RTC_DRV_AT91SAM9

Linux Kernel Configuration
└─>Device Drivers
└─>Real Time Clock
└─>AT91SAM9x
In linux kernel since version 2.6.25 (release Date: 2008-04-16)  
RTC driver for the Atmel AT91SAM9x internal RTT (Real Time Timer).
These timers are powered by the backup power supply (such as a
small coin cell battery), but do not need to be used as RTCs.

(On AT91SAM9rl chips you probably want to use the dedicated RTC
module and leave the RTT available for other uses.)

source code: