TX2's device tree

Hello, I would like to activate the SPI of TX2’s J21 header.
Spidev 3.0 is enabled on the /dev path, but does not appear when you check the waveform with the oscilloscope.
So I’m looking for a device tree file on TX2, but I can’t find it.
What should I do?

Thank you.

Have a reference to below link to check the pinmux setting.

Sorry, I can’t see the link.

Update the link in original comment.