default or selected kernelversion does not have config value CONFIG_JS_RTC.
Result is shown for kernelversion 6.8.2

Enhanced Real Time Clock Support

modulename: js-rtc.ko

configname: CONFIG_JS_RTC

Linux Kernel Configuration
└─>Device Drivers
└─>Character devices
└─>Enhanced Real Time Clock Support
In linux kernel since version 2.6.24 (release Date: 2008-01-24)  
If you say Y here and create a character special file /dev/rtc with
major number 10 and minor number 135 using mknod ("man mknod"), you
will get access to the real time clock (or hardware clock) built
into your computer.

Every PC has such a clock built in. It can be used to generate
signals from as low as 1Hz up to 8192Hz, and can also be used
as a 24 hour alarm. It reports status information via the file
/proc/driver/rtc and its behaviour is set by various ioctls on

If you think you have a use for such a device (such as periodic data
sampling), then say Y here, and read Documentation/rtc.txt
for details.

To compile this driver as a module, choose M here: the
module will be called js-rtc.

source code: