COMX drivers for the 2.2 kernel Originally written by: Tivadar Szemethy, Currently maintained by: Gergely Madarasz Last change: 21/06/1999. INTRODUCTION This document describes the software drivers and their use for the COMX line of synchronous serial adapters for Linux version 2.2.0 and above. The cards are produced and sold by ITC-Pro Ltd. Budapest, Hungary For further info contact or http://www.itc.hu (mostly in Hungarian). The firmware files and software are available from ftp://ftp.itc.hu Currently, the drivers support the following cards and protocols: COMX (2x64 kbps intelligent board) CMX (1x256 + 1x128 kbps intelligent board) HiCOMX (2x2Mbps intelligent board) LoCOMX (1x512 kbps passive board) MixCOM (1x512 or 2x512kbps passive board with a hardware watchdog an optional BRI interface and optional flashROM (1-32M)) At the moment of writing this document, the (Cisco)-HDLC, LAPB, SyncPPP and Frame Relay (DTE, rfc1294 IP encapsulation with partially implemented Q933a LMI) protocols are available as link-level protocol. X.25 support is being worked on. USAGE Load the comx.o module and the hardware-specific and protocol-specific modules you'll need into the running kernel using the insmod utility. This creates the /proc/comx directory. See the example scripts in the 'etc' directory. /proc INTERFACE INTRO The COMX driver set has a new type of user interface based on the /proc filesystem which eliminates the need for external user-land software doing IOCTL calls. Each network interface or device (i.e. those ones you configure with 'ifconfig' and 'route' etc.) has a corresponding directory under /proc/comx. You can dynamically create a new interface by saying 'mkdir /proc/comx/comx0' (or you can name it whatever you want up to 8 characters long, comx[n] is just a convention). Generally the files contained in these directories are text files, which can be viewed by 'cat filename' and you can write a string to such a file by saying 'echo _string_ >filename'. This is very similar to the sysctl interface. Don't use a text editor to edit these files, always use 'echo' (or 'cat' where appropriate). When you've created the comx[n] directory, two files are created automagically in it: 'boardtype' and 'protocol'. You have to fill in these files correctly for your board and protocol you intend to use (see the board and protocol descriptions in this file below or the example scripts in the 'etc' directory). After filling in these files, other files will appear in the directory for setting the various hardware- and protocol-related informations (for example irq and io addresses, keepalive values etc.) These files are set to default values upon creation, so you don't necessarily have to change all of them. When you're ready with filling in the files in the comx[n] directory, you can configure the corresponding network interface with the standard network configuration utilities. If you're unable to bring the interfaces up, look up the various kernel log files on your system, and consult the messages for a probable reason. EXAMPLE To create the interface 'comx0' which is the first channel of a COMX card: insmod comx # insmod comx-hw-comx ; insmod comx-proto-hdlc (these are usually autoloaded if you use the kernel module loader) mkdir /proc/comx/comx0 echo comx >/proc/comx/comx0/boardtype echo 0x360 >/proc/comx/comx0/io <- jumper-selectable I/O port echo 0x0a >/proc/comx/comx0/irq <- jumper-selectable IRQ line echo 0xd000 >/proc/comx/comx0/memaddr <- software-configurable memory address. COMX uses 64 KB, and this can be: 0xa000, 0xb000, 0xc000, 0xd000, 0xe000. Avoid conflicts with other hardware. cat /proc/comx/comx0/firmware <- the firmware for the card echo HDLC >/proc/comx/comx0/protocol <- the data-link protocol echo 10 >/proc/comx/comx0/keepalive <- the keepalive for the protocol ifconfig comx0 1.2.3.4 pointopoint 5.6.7.8 netmask 255.255.255.255 <- finally configure it with ifconfig Check its status: cat /proc/comx/comx0/status If you want to use the second channel of this board: mkdir /proc/comx/comx1 echo comx >/proc/comx/comx1/boardtype echo 0x360 >/proc/comx/comx1/io echo 10 >/proc/comx/comx1/irq echo 0xd000 >/proc/comx/comx1/memaddr echo 1 >/proc/comx/comx1/channel <- channels are numbered as 0 (default) and 1 Now, check if the driver recognized that you're going to use the other channel of the same adapter: cat /proc/comx/comx0/twin comx1 cat /proc/comx/comx1/twin comx0 You don't have to load the firmware twice, if you use both channels of an adapter, just write it into the channel 0's /proc firmware file. Default values: io 0x360 for COMX, 0x320 (HICOMX), irq 10, memaddr 0xd0000 THE LOCOMX HARDWARE DRIVER The LoCOMX driver doesn't require firmware, and it doesn't use memory either, but it uses DMA channels 1 and 3. You can set the clock rate (if enabled by jumpers on the board) by writing the kbps value into the file named 'clock'. Set it to 'external' (it is the default) if you have external clock source. (Note: currently the LoCOMX driver does not support the internal clock) THE COMX, CMX AND HICOMX DRIVERS On the HICOMX, COMX and CMX, you have to load the firmware (it is different for the three cards!). All these adapters can share the same memory address (we usually use 0xd0000). On the CMX you can set the internal clock rate (if enabled by jumpers on the small adapter boards) by writing the kbps value into the 'clock' file. You have to do this before initializing the card. If you use both HICOMX and CMX/COMX cards, initialize the HICOMX first. The I/O address of the HICOMX board is not configurable by any method available to the user: it is hardwired to 0x320, and if you have to change it, consult ITC-Pro Ltd. THE MIXCOM DRIVER The MixCOM board doesn't require firmware, the driver communicates with it through I/O ports. You can have three of these cards in one machine. THE HDLC LINE PROTOCOL DRIVER There's only one configurable parameter with this protocol: the 'keepalive' value. You can set this in seconds or set to 'off'. Agree with the administrator of your peer router on this setting. The default is 10 (seconds). EXAMPLE (setting up hw parameters, see above) echo hdlc >/proc/comx/comx0/protocol echo 10 >/proc/comx/comx0/keepalive <- not necessary, 10 is the default ifconfig comx0 1.2.3.4 pointopoint 5.6.7.8 netmask 255.255.255.255 THE PPP LINE PROTOCOL DRIVER To use this driver, you have to have ppp-2.3.4, and have a modified version of pppd (this pppd will work as async pppd to, the modifiactions merely relax some restricions in order to be able to use non-async lines too. If configured, this driver can use Van Jacobson TCP header compression (you'll need the slhc.o module for this). Additionaly to use this protocol, enable async ppp in your kernel config, and create the comx device special files in /dev. They're character special files with major 88, and their names must be the same as their network interface counterparts (i.e /dev/comx0 with minor 0 corresponds interface comx0 and so on). EXAMPLE (setting up hw parameters, see above) echo ppp >/proc/comx/comx0/protocol ifconfig comx0 up pppd comx0 1.2.3.4:5.6.7.8 persist <- with this option pppd won't exit when the line goes down THE LAPB LINE PROTOCOL DRIVER For this, you'll need to configure LAPB support (See 'LAPB Data Link Driver' in 'Network options' section) into your kernel (thanks to Jonathan Naylor for his excellent implementation). comxlapb.o provides the following files in the appropriate directory (the default values in parens): t1 (5), t2 (1), n2 (20), mode (DTE, STD) and window (7). Agree with the administrator of your peer router on these settings (most people use defaults, but you have to know if you are DTE or DCE). EXAMPLE (setting up hw parameters, see above) echo lapb >/proc/comx/comx0/protocol echo dce >/proc/comx/comx0/mode <- DCE interface in this example ifconfig comx0 1.2.3.4 pointopoint 5.6.7.8 netmask 255.255.255.255 THE FRAME RELAY PROTOCOL DRIVER You DON'T need any other frame relay related modules from the kernel to use COMX-Frame Relay. This protocol is a bit more complicated than the others, because it allows to use 'subinterfaces' or DLCIs within one physical device. First you have to create the 'master' device (the actual physical interface) as you would do for other protocols. Specify 'frad' as protocol type. Now you can bring this interface up by saying 'ifconfig comx0 up' (or whatever you've named the interface). Do not assign any IP address to this interface and do not set any routes through it. Then, set up your DLCIs the following way: create a comx interface for each DLCI you intend to use (with mkdir), and write 'dlci' to the 'boardtype' file, and 'ietf-ip' to the 'protocol' file. Currently, the only supported encapsulation type is this (also called as RFC1294/1490 IP encapsulation). Write the DLCI number to the 'dlci' file, and write the name of the physical COMX device to the file called 'master'. Now you can assign an IP address to this interface and set routes using it. See the example file for further info and example config script. Notes: this driver implements a DTE interface with partially implemented Q933a LMI. You can find an extensively commented example in the 'etc' directory. FURTHER /proc FILES boardtype: Type of the hardware. Valid values are: 'comx', 'hicomx', 'locomx', 'cmx'. protocol: Data-link protocol on this channel. Can be: HDLC, LAPB, PPP, FRAD status: You can read the channel's actual status from the 'status' file, for example 'cat /proc/comx/comx3/status'. lineup_delay: Interpreted in seconds (default is 1). Used to avoid line jitter: the system will consider the line status 'UP' only if it is up for at least this number of seconds. debug: You can set various debug options through this file. Valid options are: 'comx_events', 'comx_tx', 'comx_rx', 'hw_events', 'hw_tx', 'hw_rx'. You can enable a debug options by writing its name prepended by a '+' into the debug file, for example 'echo +comx_rx >comx0/debug'. Disabling an option happens similarly, use the '-' prefix (e.g. 'echo -hw_rx >debug'). Debug results can be read from the debug file, for example: tail -f /proc/comx/comx2/debug