[TriEmbed] Is that ttyUSB0 or ttyUSB1 this time?

[Pete Soper]

My memory was off: was using symlinks. The script below after === did 
the work. After --- are my udev rules. This all ran on Ubuntu (probably 
16.04).

Many little local files having meaningful labels. File names with the 
file contents to the right of the name:

DM01L0P2 SW-GW-CELL
DM01L2BU GW-USB2
DM01LZ2F SW-GW-WIFI
DO00W275 GW-USB4
DO00WYOK GW-USB0
DO00WYOT GW-USB3
DO01TY7B GW-USB1
L2000G0A X-SP1___
L20900F01 X-SP2___
X-NC____ DEB-NC-SERIAL
X-NE____ DEB-NE-SERIAL
X-NW____ DEB-NW-SERIAL
X-SWCELL DEB-SW-CELL-SERIAL
X-SWWIFI DEB-SW-WIFI-SERIAL

--------------------------------------------

SUBSYSTEMS=="usb", ATTRS{serial}=="DO00WYOK", ATTRS{product}=="FT230X 
Basic UART", ATTRS{idProduct}=="6015", ATTRS{idVendor}=="0403", 
MODE="0666", GROUP:=dialout", SYMLINK="GW0" # GW-USB0
SUBSYSTEMS=="usb", ATTRS{serial}=="DO01TY7B", ATTRS{product}=="FT230X 
Basic UART", ATTRS{idProduct}=="6015", ATTRS{idVendor}=="0403", 
MODE="0666", GROUP:=dialout", SYMLINK="GW0" # GW-USB1
SUBSYSTEMS=="usb", ATTRS{serial}=="DM01L2BU", ATTRS{product}=="FT230X 
Basic UART", ATTRS{idProduct}=="6015", ATTRS{idVendor}=="0403", 
MODE="0666", GROUP:=dialout", SYMLINK="GW1" # GW-USB2
SUBSYSTEMS=="usb", ATTRS{serial}=="DO00WYOT", ATTRS{product}=="FT230X 
Basic UART", ATTRS{idProduct}=="6015", ATTRS{idVendor}=="0403", 
MODE="0666", GROUP:=dialout", SYMLINK="GW0" # GW-USB3
SUBSYSTEMS=="usb", ATTRS{serial}=="DM01L0P2", ATTRS{product}=="FT230X 
Basic UART", ATTRS{idProduct}=="6015", ATTRS{idVendor}=="0403", 
MODE="0666", GROUP:=dialout", SYMLINK="DM01L0P2" # SW-GW-USB0
SUBSYSTEMS=="usb", ATTRS{serial}=="DM01LZ2F", ATTRS{product}=="FT230X 
Basic UART", ATTRS{idProduct}=="6015", ATTRS{idVendor}=="0403", 
MODE="0666", GROUP:="dialout", SYMLINK="DM01LZ2F" # SW-GW-USB1
SUBSYSTEMS=="usb", ATTRS{serial}=="DM01LZ2F", ATTRS{product}=="FT230X 
Basic UART", ATTRS{idProduct}=="bef3", ATTRS{idVendor}=="0451", 
MODE="0666", GROUP:="dialout", SYMLINK="DM01LZ2F" # SW-GW-USB1

===================

#!/bin/sh

# This script creates symbolic links in /dev with meaningful names to actual
# devices that are highly volatile as USB connections change over time. It's
# in two pieces: A general mechanism that works for simple serial USB
# devices like FTDI chips followed by a specialized mechanism for 
handling one
# of TI's standard debug probes.

# Make symbolic links (with "dialout" group for terminal emulator 
access) for
# USB devices. For each USB serial string value a meaningful name stored in
# a file of the same name in the command's directory is used to create the
# symbolic link. Tested with X64 Ubuntu 18.04.

# This depends on udev rules such as this one:

#SUBSYSTEMS=="usb", ATTRS{serial}=="DM01LZ2F", ATTRS{product}=="FT230X 
Basic UAR
T", ATTRS{idProduct}=="6015", ATTRS{idVendor}=="0403", MODE="0666", 
GROUP="dialo
ut", SYMLINK="DM01LZ2F" # SW-PD-USB1

# By convention the comment shows the symlink that will be created in 
/dev to
# access the device matched. There must be a file in the same directory 
as this
# command named "DM01LZ2F" containing the string "SW-PD-USB1" for this 
example.

# Also find all the symlinks in /dev/serial/by-id that have an assigned 
XDS110
# serial string we know about (a second list of names that have to be files
# in the directory containing this command). For these the second serial
# device assigned by the TI udev rules is linked to from the name 
contained in
# the label file. The second of the two devices supports debug I/O via JTDI
# and JTDO pins in the target chip (that can be driven by a real or emulated
# UART.

# Apex Proto Factory March, 2019 MIT license

FILEPATH=`dirname $0`

# Traverse the list of unique USB serial attribute values to be matched
# This works for vanilla USB serial devices such as those with FTDI chips

for id in DO00W275 DO00WYOT DO00WYOK DM01L2BU DO01TY7B DM01L0P2 DM01LZ2F 
; do

   # Fetch the symlink name

   label=`cat $FILEPATH/$id`

   if [ -h /dev/$id ] ; then

     devname=`ls -l /dev/serial/by-id/*$id* | sed -e"s at .*tty\(.*\)@\1@"`

     # It's quite likely the symlink exists already, so blow it away if so

     sudo rm -f /dev/$label

     # Create the link and assign it to the dialup group

     sudo ln -s /dev/tty$devname /dev/$label
     sudo chgrp -h dialout /dev/$label
     echo "ID: $id DEV: /dev/$label"

   fi # // matching symlink in /dev

done # traversing serial ids

# Now traverse all the TI XDS110 debugger serial strings that might be
# in /dev/serial/by-id

for id in L2000F01  X-NC____ X-NE____ X-NW____ X-SWCELL X-SWWIFI ; do

   ls /dev/serial/by-id/*$id* >/dev/null 2>&1

   if [ $? -ne 2 ] ; then

     # There is a symlink in by-id with the current id being handled

     # For TI XDS110 devices there are two serial devices: ACMn and ACMn+1
     # We want to ignore ACMn and only make a symlink to ACMn+1 for access
     # to the exported serial connection to the target (via JTDI/JTDO). 
So use
     # a flag to ignore the first entry. We're banking on the ls to offer
     # ACMn lexically ahead of ACMn+1. If its random this will just get 
harder.

     seenfirst=0

     ls /dev/serial/by-id/*$id* | while read f ; do

       if [ $seenfirst -eq 0 ] ; then

         seenfirst=1
         continue  # go to next loop iteration

       else

         # Found the second device of the pair. Fetch the symlink name and
         # remove any stale instance

         label=`cat $FILEPATH/$id`
         sudo rm -f /dev/$label

         # Now add the link and assign it to the dialup group
         path=`readlink -f "$f"`

         sudo ln -s $path /dev/$label
         sudo chgrp -h dialout /dev/$label
         echo "ID: $id DEV: /dev/$label"

       fi # first or second device of pair

     done # traversing serial device pair

   fi # symlink pair found in by-id

done # traversing XDS110 serial ids

On 2/19/21 6:33 PM, Michael Monaghan via TriEmbed wrote:
> Pete,
>
> Do you have an example?  I've never tried hard links.
>