Driver for the Intel Wireless Wimax Connection 2400m

   (C) 2008 Intel Corporation < [email protected] >

   This provides a driver for the Intel Wireless WiMAX Connection 2400m
   and a basic Linux kernel WiMAX stack.

1. Requirements

     * Linux installation with Linux kernel 2.6.22 or newer (if building
       from a separate tree)
     * Intel i2400m Echo Peak or Baxter Peak; this includes the Intel
       Wireless WiMAX/WiFi Link 5x50 series.
     * build tools:
          + Linux kernel development package for the target kernel; to
            build against your currently running kernel, you need to have
            the kernel development package corresponding to the running
            image installed (usually if your kernel is named
            linux-VERSION, the development package is called
            linux-dev-VERSION or linux-headers-VERSION).
          + GNU C Compiler, make

2. Compilation and installation

2.1. Compilation of the drivers included in the kernel

   Configure the kernel; to enable the WiMAX drivers select Drivers >
   Networking Drivers > WiMAX device support. Enable all of them as
   modules (easier).

   If USB or SDIO are not enabled in the kernel configuration, the options
   to build the i2400m USB or SDIO drivers will not show. Enable said
   subsystems and go back to the WiMAX menu to enable the drivers.

   Compile and install your kernel as usual.

2.2. Compilation of the drivers distributed as an standalone module

   To compile

$ cd source/directory
$ make

   Once built you can load and unload using the provided load.sh script;
   load.sh will load the modules, load.sh u will unload them.

   To install in the default kernel directories (and enable auto loading
   when the device is plugged):

$ make install
$ depmod -a

   If your kernel development files are located in a non standard
   directory or if you want to build for a kernel that is not the
   currently running one, set KDIR to the right location:

$ make KDIR=/path/to/kernel/dev/tree

   For more information, please contact [email protected].

3. Installing the firmware

   The firmware can be obtained from http://linuxwimax.org or might have
   been supplied with your hardware.

   It has to be installed in the target system:
     *
$ cp FIRMWAREFILE.sbcf /lib/firmware/i2400m-fw-BUSTYPE-1.3.sbcf

     * NOTE: if your firmware came in an .rpm or .deb file, just install
       it as normal, with the rpm (rpm -i FIRMWARE.rpm) or dpkg
       (dpkg -i FIRMWARE.deb) commands. No further action is needed.
     * BUSTYPE will be usb or sdio, depending on the hardware you have.
       Each hardware type comes with its own firmware and will not work
       with other types.

4. Design

   This package contains two major parts: a WiMAX kernel stack and a
   driver for the Intel i2400m.

   The WiMAX stack is designed to provide for common WiMAX control
   services to current and future WiMAX devices from any vendor; please
   see README.wimax for details.

   The i2400m kernel driver is broken up in two main parts: the bus
   generic driver and the bus-specific drivers. The bus generic driver
   forms the drivercore and contain no knowledge of the actual method we
   use to connect to the device. The bus specific drivers are just the
   glue to connect the bus-generic driver and the device. Currently only
   USB and SDIO are supported. See drivers/net/wimax/i2400m/i2400m.h for
   more information.

   The bus generic driver is logically broken up in two parts: OS-glue and
   hardware-glue. The OS-glue interfaces with Linux. The hardware-glue
   interfaces with the device on using an interface provided by the
   bus-specific driver. The reason for this breakup is to be able to
   easily reuse the hardware-glue to write drivers for other OSes; note
   the hardware glue part is written as a native Linux driver; no
   abstraction layers are used, so to port to another OS, the Linux kernel
   API calls should be replaced with the target OS's.

5. Usage

   To load the driver, follow the instructions in the install section;
   once the driver is loaded, plug in the device (unless it is permanently
   plugged in). The driver will enumerate the device, upload the firmware
   and output messages in the kernel log (dmesg, /var/log/messages or
   /var/log/kern.log) such as:

...
i2400m_usb 5-4:1.0: firmware interface version 8.0.0
i2400m_usb 5-4:1.0: WiMAX interface wmx0 (00:1d:e1:01:94:2c) ready

   At this point the device is ready to work.

   Current versions require the Intel WiMAX Network Service in userspace
   to make things work. See the network service's README for instructions
   on how to scan, connect and disconnect.

5.1. Module parameters

   Module parameters can be set at kernel or module load time or by
   echoing values:

$ echo VALUE > /sys/module/MODULENAME/parameters/PARAMETERNAME

   To make changes permanent, for example, for the i2400m module, you can
   also create a file named /etc/modprobe.d/i2400m containing:

options i2400m idle_mode_disabled=1

   To find which parameters are supported by a module, run:

$ modinfo path/to/module.ko

   During kernel bootup (if the driver is linked in the kernel), specify
   the following to the kernel command line:

i2400m.PARAMETER=VALUE

5.1.1. i2400m: idle_mode_disabled

   The i2400m module supports a parameter to disable idle mode. This
   parameter, once set, will take effect only when the device is
   reinitialized by the driver (eg: following a reset or a reconnect).

5.2. Debug operations: debugfs entries

   The driver will register debugfs entries that allow the user to tweak
   debug settings. There are three main container directories where
   entries are placed, which correspond to the three blocks a i2400m WiMAX
   driver has:
     * /sys/kernel/debug/wimax:DEVNAME/ for the generic WiMAX stack
       controls
     * /sys/kernel/debug/wimax:DEVNAME/i2400m for the i2400m generic
       driver controls
     * /sys/kernel/debug/wimax:DEVNAME/i2400m-usb (or -sdio) for the
       bus-specific i2400m-usb or i2400m-sdio controls).

   Of course, if debugfs is mounted in a directory other than
   /sys/kernel/debug, those paths will change.

5.2.1. Increasing debug output

   The files named *dl_* indicate knobs for controlling the debug output
   of different submodules:
     *
# find /sys/kernel/debug/wimax\:wmx0 -name \*dl_\*
/sys/kernel/debug/wimax:wmx0/i2400m-usb/dl_tx
/sys/kernel/debug/wimax:wmx0/i2400m-usb/dl_rx
/sys/kernel/debug/wimax:wmx0/i2400m-usb/dl_notif
/sys/kernel/debug/wimax:wmx0/i2400m-usb/dl_fw
/sys/kernel/debug/wimax:wmx0/i2400m-usb/dl_usb
/sys/kernel/debug/wimax:wmx0/i2400m/dl_tx
/sys/kernel/debug/wimax:wmx0/i2400m/dl_rx
/sys/kernel/debug/wimax:wmx0/i2400m/dl_rfkill
/sys/kernel/debug/wimax:wmx0/i2400m/dl_netdev
/sys/kernel/debug/wimax:wmx0/i2400m/dl_fw
/sys/kernel/debug/wimax:wmx0/i2400m/dl_debugfs
/sys/kernel/debug/wimax:wmx0/i2400m/dl_driver
/sys/kernel/debug/wimax:wmx0/i2400m/dl_control
/sys/kernel/debug/wimax:wmx0/wimax_dl_stack
/sys/kernel/debug/wimax:wmx0/wimax_dl_op_rfkill
/sys/kernel/debug/wimax:wmx0/wimax_dl_op_reset
/sys/kernel/debug/wimax:wmx0/wimax_dl_op_msg
/sys/kernel/debug/wimax:wmx0/wimax_dl_id_table
/sys/kernel/debug/wimax:wmx0/wimax_dl_debugfs

   By reading the file you can obtain the current value of said debug
   level; by writing to it, you can set it.

   To increase the debug level of, for example, the i2400m's generic TX
   engine, just write:

$ echo 3 > /sys/kernel/debug/wimax:wmx0/i2400m/dl_tx

   Increasing numbers yield increasing debug information; for details of
   what is printed and the available levels, check the source. The code
   uses 0 for disabled and increasing values until 8.

5.2.2. RX and TX statistics

   The i2400m/rx_stats and i2400m/tx_stats provide statistics about the
   data reception/delivery from the device:

$ cat /sys/kernel/debug/wimax:wmx0/i2400m/rx_stats
45 1 3 34 3104 48 480

   The numbers reported are
     * packets/RX-buffer: total, min, max
     * RX-buffers: total RX buffers received, accumulated RX buffer size
       in bytes, min size received, max size received

   Thus, to find the average buffer size received, divide accumulated
   RX-buffer / total RX-buffers.

   To clear the statistics back to 0, write anything to the rx_stats file:

$ echo 1 > /sys/kernel/debug/wimax:wmx0/i2400m_rx_stats

   Likewise for TX.

   Note the packets this debug file refers to are not network packet, but
   packets in the sense of the device-specific protocol for communication
   to the host. See drivers/net/wimax/i2400m/tx.c.

5.2.3. Tracing messages received from user space

   To echo messages received from user space into the trace pipe that the
   i2400m driver creates, set the debug file i2400m/trace_msg_from_user to
   1:
     *
$ echo 1 > /sys/kernel/debug/wimax:wmx0/i2400m/trace_msg_from_user

5.2.4. Performing a device reset

   By writing a 0, a 1 or a 2 to the file
   /sys/kernel/debug/wimax:wmx0/reset, the driver performs a warm (without
   disconnecting from the bus), cold (disconnecting from the bus) or bus
   (bus specific) reset on the device.

5.2.5. Asking the device to enter power saving mode

   By writing any value to the /sys/kernel/debug/wimax:wmx0 file, the
   device will attempt to enter power saving mode.

6. Troubleshooting

6.1. Driver complains about 'i2400m-fw-usb-1.2.sbcf: request failed'

   If upon connecting the device, the following is output in the kernel
   log:

i2400m_usb 5-4:1.0: fw i2400m-fw-usb-1.3.sbcf: request failed: -2

   This means that the driver cannot locate the firmware file named
   /lib/firmware/i2400m-fw-usb-1.2.sbcf. Check that the file is present in
   the right location.