wimax: documentation for the stack

wimax documentation

Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

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+   Linux kernel WiMAX stack
+
+   (C) 2008 Intel Corporation < linux-wimax@intel.com >
+
+   This provides a basic Linux kernel WiMAX stack to provide a common
+   control API for WiMAX devices, usable from kernel and user space.
+
+1. Design
+
+   The WiMAX stack is designed to provide for common WiMAX control
+   services to current and future WiMAX devices from any vendor.
+
+   Because currently there is only one and we don't know what would be the
+   common services, the APIs it currently provides are very minimal.
+   However, it is done in such a way that it is easily extensible to
+   accommodate future requirements.
+
+   The stack works by embedding a struct wimax_dev in your device's
+   control structures. This provides a set of callbacks that the WiMAX
+   stack will call in order to implement control operations requested by
+   the user. As well, the stack provides API functions that the driver
+   calls to notify about changes of state in the device.
+
+   The stack exports the API calls needed to control the device to user
+   space using generic netlink as a marshalling mechanism. You can access
+   them using your own code or use the wrappers provided for your
+   convenience in libwimax (in the wimax-tools package).
+
+   For detailed information on the stack, please see
+   include/linux/wimax.h.
+
+2. Usage
+
+   For usage in a driver (registration, API, etc) please refer to the
+   instructions in the header file include/linux/wimax.h.
+
+   When a device is registered with the WiMAX stack, a set of debugfs
+   files will appear in /sys/kernel/debug/wimax:wmxX can tweak for
+   control.
+
+2.1. Obtaining debug information: debugfs entries
+
+   The WiMAX stack is compiled, by default, with debug messages that can
+   be used to diagnose issues. By default, said messages are disabled.
+
+   The drivers will register debugfs entries that allow the user to tweak
+   debug settings.
+
+   Each driver, when registering with the stack, will cause a debugfs
+   directory named wimax:DEVICENAME to be created; optionally, it might
+   create more subentries below it.
+
+2.1.1. Increasing debug output
+
+   The files named *dl_* indicate knobs for controlling the debug output
+   of different submodules of the WiMAX stack:
+     *
+# find /sys/kernel/debug/wimax\:wmx0 -name \*dl_\*
+/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
+/sys/kernel/debug/wimax:wmx0/.... # other driver specific files
+
+       NOTE: Of course, if debugfs is mounted in a directory other than
+       /sys/kernel/debug, those paths will change.
+
+   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 id-table submodule,
+   just write:
+
+$ echo 3 > /sys/kernel/debug/wimax:wmx0/wimax_dl_id_table
+
+   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.