Programmatically load device tree overlay in Go

[Frank Davidson]

Hi,

I am having a hard time understanding the nature of the "echo cape-bone-iio > /sys/devices/bone_capemgr.*/slots"

I have written the following program in Go:

package bbbdevtreeovly

import (

// "io"

// "bytes"

// "fmt"

"io/ioutil"

"log"

"os"

// "os/exec"

// "strings"

"path/filepath"

)

const (

slotsDir string = `/sys/devices/` // Find BBB's slots

)

func Load_dto(dtoFileName string, dtoFilePath string) (err error) {

log.SetPrefix(`BBB Device Tree Overlay: `)

slotFiles := make([]os.FileInfo, 100)

slotFiles, err = ioutil.ReadDir(slotsDir)

var i int

for i = 0; i < len(slotFiles); i++ {

found, _ := filepath.Match(`bone_capemgr.*`, slotFiles[i].Name())

if found {

break

}

}

log.Println("This is the new program...", "\n")

slotsLoc := filepath.Join(slotsDir, slotFiles[i].Name(), `slots`)

log.Println("DTO File: ", dtoFileName, "\n")

slots, err := os.Open(slotsLoc)

if err != nil {

log.Println(err)

return err

}

defer slots.Close()

log.Println("Slots location: ", slots.Name(), "\n")

slots.Write([]byte(dtoFileName))

// slots.Write([]byte("cape_bone_iio"))

return nil

}

/*

 *

 */

package main

import (

"davidsonff/fmserve/bbbdevtreeovly"

"fmt"

)

func main() {

err := bbbdevtreeovly.Load_dto("cape-bone-iio", "/lib/firmware/")

if err != nil {

panic(err)

}

fmt.Println("Success!")

}

The result is no error and no change in the system:

root@beaglebone:~# ./fmserve

BBB Device Tree Overlay: 2013/12/15 19:25:15 This is the new program...

BBB Device Tree Overlay: 2013/12/15 19:25:15 DTO File:  cape-bone-iio

BBB Device Tree Overlay: 2013/12/15 19:25:15 Slots location:  /sys/devices/bone_capemgr.9/slots

Success!

root@beaglebone:~# cat /sys/devices/bone_capemgr.9/slots

 0: 54:PF---

 1: 55:PF---

 2: 56:PF---

 3: 57:PF---

 4: ff:P-O-L Bone-LT-eMMC-2G,00A0,Texas Instrument,BB-BONE-EMMC-2G

 5: ff:P-O-L Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI

It seems to me that the $SLOTS "file" is not a normal file and that I am not understanding it properly.

I've seen posts on loading this at boot in a script file, but nothing about changing it programmatically... Any help would be appreciated!

Thanks,

Frank

[Thorsten von Eicken]

Do you perhaps need a newline terminator for the line you're writing to the slots "file"?

[Frank Davidson]

Thanks, Thorsten, but that didn't see to help, unfortunately... It doesn't generate any errors, it just doesn't actually load the dto... Any other ideas?

Frank

[Thorsten von Eicken]

What does dmesg say? That's where you'd find any error messages.

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