Syntax for dts file error. Trying to make an overlay for connecting to PRU R30 register

[Charles Kerr]

I can't find my old post, so I apologize for any repeat post.

I am trying to allocate two pins (P8_12,P8_46) to PRU0 and PRU1.   So effectively mode 6 and mode 5.  I want to exclusively use these by the pru(s).  Still trying to understand this device tree overlay, but I found an example one and modified it. It gives a syntax error when ti toy to compile it (dtc).  After beating my head against the wall, I am hoping a second set of eyes will be helpful.  Any help one can give on the syntax error (and if the dts file won't accomplish what the desire for these pins).

/*

    * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/

    *

    * This program is free software; you can redistribute it and/or modify

    * it under the terms of the GNU General Purpose License Version 2 as

    * published by the Free Software Foundation

    *

    * Original from: github.com/jadonk/validation-scripts/blob/master/test-capemgr/

    *

    * Modified by Derek Molloy for the example on www.derekmolloy.ie

    * that maps GPIO pins for the example

    */

    /dts-v1/;

    /plugin/;

    /{

        compatible = "ti,beaglebone", "ti,beaglebone-black";

        part-number = "DIYBLIGHTS";

        version = "00A0";

        exclusive-use = "P8.12,P8.46"

        fragment@0 {

            target = <&am33xx_pinmux>;

            __overlay__ {

                pinctrl_test: DM_GPIO_Test_Pins {

                    pinctrl-single,pins = <

                        0x003 0x06  /* P8_12 GPIO:44 $PINS:12 MODE 6 -pru0 R30_14 */

                        0x0A4 0x05  /* P8_46 GPIO:71 $PINS:41 MODE 5 - pru1 R30_1 */

                    >;

                };

            };

        };

        fragment@1 {

            target = <&ocp>;

            __overlay__ {

                test_helper: helper {

                    compatible = "bone-pinmux-helper";

                    pinctrl-names = "default";

                    pinctrl-0 = <&pinctrl_test>;

                    status = "okay";

                };

            };

        };

    };

Again, thanks ahead for any hep one can offer!

Charles

[TJF]

Hi Charles!

Drop all that device tree stuff. Instead use the elegant way for pinmuxing: libpruio. Side effects: faster booting time, smaller memory footprint.

Find example code for pinmuxing, downloading and running PRU firmware at

http://users.freebasic-portal.de/tjf/Projekte/libpruio/doc/html/pruss__toggle_8c_source.html

In your case the following code will do the trick (note: single source, pinmuxing in your program code)

if (io->setPin(io, P8_12, 6)) {

        printf("P8_12 configuration failed (%s)\n", io->Errr); break;}

if (io->setPin(io, P8_46, 5)) {

        printf("P8_46 configuration failed (%s)\n", io->Errr); break;}

Regards

[kerrb...@gmail.com]

Ok, so I got it working, so will post in case others face the same issue.  First, the syntax issue was a missing ";" after the exclusive use tag.  Also, I had some references using the wrong labels.  What wold be great if a write up on the current use and sections of the device tree for the beaglebone black.  Right now one must be knowledgeable in all things (PRU assembly, mapping memory to a arm program to read/write, tools to build the PRU, how to activate it, and finally device tree).  Although I know the basic concept of the device tree, known what to put for the sections (PRUSS, am355x, etc) and the keywords are still very much a mystery.  Hard to be knowledgable in all things and keep it a hobby).  Luckily I didn't have to disable items (although the next project I will).  Anyway, this file appears to have worked:

   /dts-v1/;

    /plugin/;

    /{

        compatible = "ti,beaglebone", "ti,beaglebone-black";

        part-number = "DIYBLIGHTS";

        version = "00A0";

        exclusive-use = "P8.12,P8.46";

        fragment@0 {

            target = <&am33xx_pinmux>;

            __overlay__ {

                diyblights: pinmux_pru_pru_pins {

                    pinctrl-single,pins = <

                        0x30 0x06  /* P8_12 GPIO:44 $PINS:12 MODE 6 -pru0 R30_14 */

                        0xA4 0x05  /* P8_46 GPIO:71 $PINS:41 MODE 5 - pru1 R30_1 */

                    >;

                };

            };

        };

        fragment@1 {

            target = <&ocp>;

            __overlay__ {

                test_helper: helper {

                    compatible = "bone-pinmux-helper";

                    pinctrl-names = "default";

                    pinctrl-0 = <&diyblights>;

                    status = "okay";

                };

            };

        };

    };