GPIO input error : Set gpio mode failed, missing file or invalid permissions.

gupta_niks · March 20, 2019, 12:07pm

I’m using Adafruit_BBIO python library for GPIO Input. Cape Universal.dtb is disabled.
Output works fine but INput throws the error. ValueError: Set gpio mode failed, missing file or invalid permissions.
Below is dts for the gpio input

/dts-v1/;

/ {
compatible = “ti,beaglebone”, “ti,beaglebone-black”;
part-number = “gpiotest-00A0”;
version = “00A0”;

fragment@0 {
target = <0xffffffff>;

overlay {

gpiotest_Pins {
pinctrl-single,pins = <0x2c 0x37 0x8c 0x37 0x20 0x37 0xcc 0x37 0xc8 0x37>;
linux,phandle = <0x1>;
phandle = <0x1>;
};
};
};

fragment@1 {
target = <0xffffffff>;

overlay {

helper {
compatible = “bone-pinmux-helper”;
pinctrl-names = “default”;
pinctrl-0 = <0x1>;
status = “okay”;
};
};
};

fixups {
am33xx_pinmux = “/fragment@0:target:0”;
ocp = “/fragment@1:target:0”;
};

local_fixups {

fragment@1 {

overlay {

helper {
pinctrl-0 = <0x0>;
};
};
};
};
};

Please suggest the issue and help with the solution.
Thank You.

Dennis_Lee_Bieber · March 20, 2019, 4:55pm

On Wed, 20 Mar 2019 05:07:32 -0700 (PDT), gupta niks
<gupta.nikhil0126@gmail.com> declaimed the
following:

I'm using Adafruit_BBIO python library for GPIO Input. Cape Universal.dtb
is disabled.
Output works fine but INput throws the error. *ValueError: Set gpio mode
failed, missing file or invalid permissions.*
Below is dts for the gpio input

The library (based upon source) relies upon using sysfs access to the
pins. I would presume (I don't read device trees; they are mysteries to me)
cape-universal creates all the needed entries for all sysfs manipulation.
If your custom DT doesn't provide the same, anything could happen.

github.com

adafruit/adafruit-beaglebone-io-python/blob/master/source/py_gpio.c

/*
Copyright (c) 2013 Adafruit

Original RPi.GPIO Author Ben Croston
Modified for BBIO Author Justin Cooper

This file incorporates work covered by the following copyright and
permission notice, all modified code adopts the original license:

Copyright (c) 2013 Ben Croston

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
of the Software, and to permit persons to whom the Software is furnished to do
so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

This file has been truncated. show original

line 117 through 151 (the actual error is one of the calls in 142/144/146
-- but note the other operations that may be needed)

github.com

adafruit/adafruit-beaglebone-io-python/blob/master/source/c_pinmux.c

#include <stdio.h>
#include <string.h>
#include <syslog.h>

#include "c_pinmux.h"
#include "common.h"


BBIO_err set_pin_mode(const char *key, const char *mode)
{
	// char ocp_dir[] defined in common.h
	char path[100]; // "/sys/devices/platform/ocp/ocp:P#_##_pinmux/state"
	char pinmux_dir[20]; // "ocp:P#_##_pinmux"
	char pin[6]; //"P#_##"
	FILE *f = NULL;

	// pin mode can not be set for the built-in USRn LEDs
	if (strncmp(key, "USR", 3) == 0) {
		return BBIO_OK;
	}

This file has been truncated. show original

is the actual code for setting the mode, and expects something in
/sys/devices/platform/ocp/<something_pinmux>/state
into which the mode is written.