AM623: PRU Support

Hello Kevin,

If we reference the AM62x datasheet, section "Device Comparision", we see that all AM62x part numbers can have a PRUSS on them. There is no difference between AM623 and AM625. What IS different is the feature value of G (no PRU) vs C (contains PRU subsystem).

Reference the AM62x datasheet, Device Comparison > PRUSS > NOTE (3): 
PRU Subsystem (PRUSS) is available when selecting an orderable part number that includes a Features code of C. Refer to Device
Naming Convention for definition of feature codes.

In Device Naming Convention, reference "Features" and "Package Designator"

So if the features entry is G, then there is no PRUSS.

Let's check for PRU references in the Linux devicetrees:

ti-processor-sdk-linux-am62xx-evm-09.00.00.03/board-support/ti-linux-kernel/arch/arm64/boot/dts/ti$ grep -r --include=k3-am62* pru
k3-am62-lp-sk.dts:&pruss {
k3-am62-main.dtsi:      pruss: pruss@30040000 {
k3-am62-main.dtsi:              compatible = "ti,am625-pruss";
k3-am62-main.dtsi:              pruss_mem: memories@0 {
k3-am62-main.dtsi:              pruss_cfg: cfg@26000 {
k3-am62-main.dtsi:                      compatible = "ti,pruss-cfg", "syscon";
k3-am62-main.dtsi:                              pruss_coreclk_mux: coreclk-mux@3c {
k3-am62-main.dtsi:                                      clocks = <&k3_clks 81 0>,  /* pruss_core_clk */
k3-am62-main.dtsi:                                               <&k3_clks 81 20>; /* pruss_iclk */
k3-am62-main.dtsi:                                      assigned-clocks = <&pruss_coreclk_mux>;
k3-am62-main.dtsi:                              pruss_iepclk_mux: iepclk-mux@30 {
k3-am62-main.dtsi:                                      clocks = <&k3_clks 81 3>,       /* pruss_iep_clk */
k3-am62-main.dtsi:                                               <&pruss_coreclk_mux>;  /* pruss_coreclk_mux */
k3-am62-main.dtsi:                                      assigned-clocks = <&pruss_iepclk_mux>;
k3-am62-main.dtsi:                                      assigned-clock-parents = <&pruss_coreclk_mux>;
k3-am62-main.dtsi:              pruss_intc: interrupt-controller@20000 {
k3-am62-main.dtsi:                      compatible = "ti,pruss-intc";
k3-am62-main.dtsi:              pru0: pru@34000 {
k3-am62-main.dtsi:                      compatible = "ti,am625-pru";
k3-am62-main.dtsi:                      firmware-name = "am62x-pru0-fw";
k3-am62-main.dtsi:                      interrupt-parent = <&pruss_intc>;
k3-am62-main.dtsi:              pru1: pru@38000 {
k3-am62-main.dtsi:                      compatible = "ti,am625-pru";
k3-am62-main.dtsi:                      firmware-name = "am62x-pru1-fw";
k3-am62-main.dtsi:                      interrupt-parent = <&pruss_intc>;
k3-am625.dtsi: * TRM: https://www.ti.com/lit/pdf/spruiv7
k3-am62a7.dtsi: * TRM: https://www.ti.com/lit/zip/spruj16

And if we look at the reference file k3-am62-lp-sk.dts, we see this important note:

/*
 * All SoC variants with the AMC package have no PRU.
 * Attempting to access the PRU on these devices will
 * result in a crash at kernel bootup.
 *
 * For now, we do not have any code that can figure out
 * the absence of the PRU by reading any SoC registers,
 * so for now disable the PRU here in the board DTS file.
 */
&pruss {
        status = "disabled";
};

And if I check the datasheet, it does seem like all AMC packages have a feature entry of G. So that comment makes sense.

Your part number has a feature code of C, so it should have a PRU subsystem. Please verify that your Linux devicetree is properly enabling the PRU subsystem.

Regards,

Nick