How to set to spi slave mode

Robotics & Edge Computing Jetson & Embedded Systems Jetson Xavier NX
11

Below is suggest.

Have connected -> SPI1_MOSI<-->SPI3_MISO, SPI1_CLK<-->SPI3_CLK, SP1_CS0 <--> SPI3_CS0  and SPI1_CS1->SPI3_CS1.

SPI1 has to be configured as Master and SPI3 has to be configured as slave in the dt and pinmux settings have to be updated. 
SPI1 DT:    
spi@3210000 {
        status = "okay";
        compatible = "nvidia,tegra186-spi";
        spi@0 {
            compatible = "spidev";
            reg = <0>;
            spi-max-frequency = <65000000>;
            controller-data {
                nvidia,enable-hw-based-cs;
            };
        };
    };

SPI3 DT
    spi@3230000 {
        status = "okay";
        compatible = "nvidia,tegra186-spi-slave";
        spi@0 {
            compatible = "spidev";
            reg = <0>;
            spi-max-frequency = <65000000>;
            controller-data {
                nvidia,enable-hw-based-cs;
            };
        };
     };

PINMUX settings are listed below for SPI1 and SP13 for loopback. (Note: SPI1 and SP3 have an internal loopback connection for Xavier)

SPI_1 pinmux settings:
PADCTL_UART_SPI1_MISO_0  (0x0243d020) =  0x440;
PADCTL_UART_SPI1_MOSI_0 (0x0243d058) =  0x440;
PADCTL_UART_SPI1_SCK_0 (0x0243d040) =  0x440;
PADCTL_UART_SPI1_CS0_0 (0x0243d010) =  0x448;
PADCTL_UART_SPI1_CS1_0 (0x0243d050) =  0x448;

SPI_3 pinmux settings:
PADCTL_UART_SPI3_MISO_0  (0x0243d008) =  0x440;
PADCTL_UART_SPI3_MOSI_0 (0x0243d060) =  0x440;
PADCTL_UART_SPI3_SCK_0 (0x0243d048) =  0x444;
PADCTL_UART_SPI3_CS0_0 (0x0243d018) =  0x448;
PADCTL_UART_SPI3_CS1_0 (0x0243d028) =  0x448;