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Linux/AM5728: SPI configuration

Eeshan Londhe
Prodigy 80 points
Part Number: AM5728
Other Parts Discussed in Thread: DRA742,

Tool/software: Linux

I am trying to enable spi on my am57xx-evm board. I have enabled through menuconfig the spidev support and can now see it under /sys/class/spidev. I have also modified my device tree file,

am57xx-evm-common.dtsi with the following:

mcspi4_pins: mcspi4_pins {
                pinctrl-single,pins = <
                        0x350 (PIN_OUTPUT | MUX_MODE2)
                        0x34C (PIN_OUTPUT | MUX_MODE2)
                        0x348 (PIN_INPUT | MUX_MODE2) 
                        0x344 (PIN_OUTPUT | MUX_MODE2)
                >;
        };

&mcspi4 {
        pinctrl-names = "default";
        pinctrl-0 = <&mcspi4_pins>;
        status = "okay";
        spidev@4 {
                  compatible = "linux, spidev";
                  spi-max-frequency = <48000000>;
                  reg = <0x0>;
                  status = "okay";
        };
};

However, I am still unable to see the spi device under /dev after rebuilding the kernel, dts files, and rebooting.

My suspicions are that:

- I may have placed these blocks of code in the wrong place in the device tree file ( or in the wrong dts file).

- And I am also not sure of what the hex values mean in the pinctrl.

I am following the instructions here to build the kernel files and dts files: http://processors.wiki.ti.com/index.php/Linux_Kernel_Users_Guide 

Please let me know of what I may be doing wrong. Thanks!

  • 0
    TI__Guru**** 393215 points
    The software team have been notified. They will respond here.

    One thing you should correct is to enable the input on the SPI clock signal. This is used for retiming of SPI receive data and SPI receive will not work otherwise.
  • 0 in reply to Biser Gatchev-XID
    TI__Guru 55345 points

    Hello Eeshan,

    Please, check this guide.
    The hex value in pinctrl is the offset address of that pin followed by mux mode and direction settings.

    Best regards,
    Kemal

  • 0 in reply to Kemal R. Shakir
    Prodigy 80 points
    Hello,
    Thanks for the clarification. my am57xx-evm.dts file is shown below exactly as how i have wrote it. Please let me know what may be wrong.

    #include "am57xx-evm-base.dts"
    #include "am57xx-evm-common-cam-mt9t111.dtsi"

    / {
    compatible = "ti,am5728-evm", "ti,am572x-beagle-x15", "ti,am5728", "ti,dra742", "ti,dra74", "ti,dra7";
    mcspi4_pins: mcspi4_pins {
    pinctrl-single,pins = <
    0x350 (PIN_OUTPUT_PULLUP | MUX_MODE2) /*mcasp5_axr1.spi4_cs0*/
    0x34C (PIN_OUTPUT_PULLUP | MUX_MODE2) /*mcasp5_axr0.spi4_d0*/
    0x348 (PIN_INPUT_PULLUP | MUX_MODE2) /*mcasp5_fsx.spi4_d1*/
    0x344 (PIN_INPUT_PULLUP | MUX_MODE2) /*mcasp5_aclkx.spi4_clk*/
    >;
    };

    };

    &mcspi4 {
    pinctrl-names = "default";
    pinctrl-0 = <&mcspi4_pins>;
    status = "okay";
    ti,pindir-d0-out-d1-in = <1>;
    spidev@0 {
    compatible = "rohm,dh2228fv";
    spi-max-frequency = <48000000>;
    reg = <0x0>;
    status = "okay";
    };
    };


    #include "am57xx-evm-cmem.dtsi"

    Please let me know if there is anything wrong here.