Change slew rate on SPI signals

I want to slow down the slew rate of the SPI1 clock and data lines. According to the Tegra datasheet, these default to being the fastest setting, but can be changed via the APB_MISC_GP_SPI1_SCK_CFGPADCTRL_0 register. I do not see a way to change that setting in the device tree. How can I access those settings?
Thanks!

If you want to configure the speed you can configure by the transfer structure.
You can reference to spidev_test utility for the -s parameter to configure the speed.

I can already change the SPI clock frequency, if that’s what you refer to by “speed”. I am looking for how to configure the slew rate.