Configuration of spi slave in device tree files for IMX8 board

[s233199]

Hello, I am writing an SPI SLAVE driver for an imx8qmlpddr4arm2 board with Yocto. I have problems adding the slave entry on the dts file. In particular, when I test the code, my slave keeps waiting for ever to receive something, even if the other board sends data.

My code:

fsl-imx8qm.dtsi:

    lpspi0: lpspi@5a000000 {
        compatible = "fsl,imx7ulp-spi";
        reg = <0x0 0x5a000000 0x0 0x10000>;
        interrupts = <GIC_SPI 216 IRQ_TYPE_LEVEL_HIGH>;
        interrupt-parent = <&gic>;
        clocks = <&clk IMX8QM_SPI0_CLK>,
             <&clk IMX8QM_SPI0_IPG_CLK>;
        clock-names = "per", "ipg";
        
        
        power-domains = <&pd_dma_lpspi0>;
        status = "disabled";
    };

fsl-imx8qm-lpddr4arm2.dts

        pinctrl_lpspi0: lpspi0grp {
            fsl,pins = <
                SC_P_SPI0_SCK_DMA_SPI0_SCK        0x0600004c
                SC_P_SPI0_SDO_DMA_SPI0_SDO        0x0600004c
                SC_P_SPI0_SDI_DMA_SPI0_SDI        0x0600004c
            >;
        };

        pinctrl_lpspi0_cs: lpspi0cs {
            fsl,pins = <
                SC_P_SPI0_CS1_DMA_SPI0_CS1        0x21
            >;
        };

&lpspi0 {
    pinctrl-names = "default";
    pinctrl-0 = <&pinctrl_lpspi0 &pinctrl_lpspi0_cs>;
    status = "okay";
    spi-slave;

    slave {
        compatible = "linux,spislave";
    };
};

Is correct to set the cs pin as DMA or it is better to set it as GPIO? What is the difference?

And the number 0x21, do I need to change something? I am reading the manual but I cannot understend what I have to modify. Can I use 0x0600004c as the other signals? I have not found anything on the web that could help me.

Thank you in advance a lot!

Erica

[igorpadykov · Accepted solution]

Hi Erica

example of i.MX8QM lpspi dts can be found on

fsl-imx8qm-lpddr4-arm2-lpspi.dts\freescale\dts\boot\arm64\arch - linux-imx - i.MX Linux kernel 

spi-fsl-lpspi.txt\spi\bindings\devicetree\Documentation - linux-imx - i.MX Linux kernel 

linux lpspidriver:  linux/drivers/spi/spi-fsl-lpspi.c

spi-fsl-lpspi.c\spi\drivers - linux-imx - i.MX Linux kernel 

For pad configuration (number 0x21,0x0600004c) one can look at documentation in SCFW Porting Kit

and fsl,imx8qm-pinctrl.txt\pinctrl\bindings\devicetree\Documentation - linux-imx - i.MX Linux kernel 

Best regards
igor
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