cti-serial

Driver, utilities and configuration for Connect Tech Xtreme 104 serial cards.

The cti_serial_core driver module is identical to version 143 from Connect Tech.

The driver creates device files, called /dev/ttyCTI*. Also see below about the cti-serial.service which creates device files with the old naming convention: /dev/ttyS*.

This repository contains a debian directory for creating a native debian package, and a build_dpkg.sh script to build it, typically in a container.

Supported Serial Cards

The cti-serial package has been tested for the Connect Tech Xtreme 104 Isolated serial card.

This is a PC/104 card, not PCI. With slight modifications it should work for other Connect Tech cards, but modifications (simplifications) for PCI will be more significant.

Contents of cti-serial package

Kernel modules

• cti_serial_core.ko

Executable binaries on /usr/bin

• arb_setbaud
• setmodem
• set485

Configuration files

• /etc/modules-load.d/cti-serial.conf: enables loading the cti_serial_core module at boot

• /etc/modprobe.d/cti-serial.conf: options for cti_serial_core

  • nr_uarts: the number of ports on the CTI card. 12 for the Xtreme/104 Isolated card.

• /etc/serial.conf: created or modified by the postinst script of cti-serial

  The postinst script for this package does the following:

  1. If /etc/serial.conf doesn't exist, it is copied from /var/lib/setserial/autoserial.conf
  2. Adds setserial entries for /dev/ttyCTI* files to /etc/serial.conf.

setserial services in Ubuntu

There are two setserial services in Ubuntu bionic (and maybe other distributions):

• setserial.service

The setserial.service invokes /etc/init.d/setserial. If /etc/serial.conf exists, then this script does nothing, otherwise it runs setserial on the entries in /var/lib/setserial/autoserial.conf.

• etc-setserial.service

The etc-setserial.service invokes /etc/init.d/etc-setserial, which runs setserial on the entires in /etc/serial.conf.

So after cti-serial is installed, /etc/serial.conf should exist and contain entries for the on-board serial ports (/dev/ttyS[0-3] on Vortex) and for the CTI ports (/dev/ttyCTI[0-11]) (assuming 12 ports). These entries will then be read by /etc/init.d/etc-setserial.

cti-serial.service

• /lib/systemd/system/cti-serial.service
• /lib/systemd/cti-serial-service.sh, script run by cti-serial.service

/lib/systemd/cti-serial-service.sh creates /dev/ttyS[4-15] which can be used instead of /dev/ttyCTI[0-11].

Number of UARTs

The Connect Tech Xtreme 104 Isolated card has 12 UARTs. So in /etc/modprobe.d/cti-serial.conf nr_uarts is set to 12. In cti-serial/driver/8205_core.c, nr_uarts defaults to 16. It doesn't hurt to leave it at 16, except that unnecessary files /dev/ttyCTI12- ttyCTI15 are created, which might mislead some users to think they are functional.

The number of UARTs on the motherboard is a kernel configuration parameter:

grep "CONFIG_SERIAL_8250_.*UARTS" /boot/config-4.15.18-vortex86dx3 

On the Vortex, with 4 UARTs on the motherboard, but CONFIG_SERIAL_8250_RUNTIME_UARTS=32, then 32 /dev/ttyS* ports are created when the 8250 serial driver is loaded, even though devices 4-31 are not functional.

To avoid conflict between the /dev/ttyS device files created by the 8250 serial driver, and the files created for backward compatiblity by cti-serial.service, the cti-serial package alters the GRUB boot line, GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub to set 8250.nr_uarts=4. Then the 8250 driver will only create device files /dev/ttyS0-ttyS3 when it is loaded.

Building cti-serial package

KERNEL_DIR

To build the cti_serial_core module, make needs to be able to find the Linux kernel headers matching the kernel version of the target system.

The headers are typically found in /usr/src, in a directory such as linux-headers-4.15.18-vortex86dx3.

To build On Debian you need to install a linux-headers package corresponding to the kernel of the target system.

For example, the header package for a Vortex DX3 running Ubuntu bionic, kernel 4.15.18:

apt-get install linux-headers-4.15.18-vortex86dx3

Assuming builds are only done in containers, not on a Vortex, the linux-headers package only needs to be installed in the container image.

The Makefile will set KERNEL_DIR to the first directory that is found on /usr/src. If there are more than one, you should move or uninstall the extra ones, or hand edit the Makefile and set the value of KERNEL_DIR. This can also be done if the headers are in some other directory than /usr/src:

KERNEL_DIR := /my/location/linux-headers-4.15.18-vortex86dx3 

Building in a Debian container

The nidas-devel package contains a start_podman script in /opt/nidas/bin which can be used to run docker/podman images for building software.

1. Clone the cti-serial repository:

    git clone https://github.com/NCAR/cti-serial.git
    cd cti-serial
   

2. Run a podman image interactively. An interactive session may be necessary if you're installing the package and the gpg-agent needs to prompt for the password to the <[email protected]> signing key.

   start_podman bionic

   1. The Ubuntu bionic image on docker.io/ncar contains the linux-headers-4.15.18-vortex86dx3 package.

      If you need to install a different header package for the target system:

       apt-get update 
       apt-get install linux-headers-x.y.z
      

   2. Edit the Makefile if you need to override the default search for KERNEL_DIR on /usr/src:

       vi /root/current/Makefile
      

   3. Build the package, which will be placed in the parent directory (/root in this example):

       cd /root/current
       ./build_dpkg.sh i386
      

   4. Add the -I option to install the package with reprepo to the EOL debian repository on /net/ftp

       ./build_dpkg.sh i386 -I bionic
      

3. To build the package non-interacively

    start_podman bionic /root/current/build_dpkg.sh i386 -I bionic