Below is one of our reference board’s DT it’s using the spi-slave mode.
And apologize for the early comment to use the spi-tegra114-slave.c, it’s should be the spi-tegra124-slave.c for the TX1, could you try to use the spi-tegra124-slave.c and I will confirm this information once I got the correct information.
spi@7000d400 {
status = "okay";
compatible = "nvidia,tegra124-spi-slave";
nvidia,clk-pin = "gpio_x5_aud_px5";
nvidia,gpio-slave-ready = <&gpio TEGRA_GPIO(K, 4) 0>; /*PK4*/
nvidia,gpio-slave-ready-active-high;
nvidia,rx-trigger-words = <0>;
};