USB: cxacru: add Documentation file
The sysfs attributes for exposing cxacru statistics/status information with
possible values is now explained in Documentation/networking/cxacru.txt
including information on the writable adsl_state attribute's commands and a
sample of the kernel log format.
Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
Cc: Duncan Sands <duncan.sands@math.u-psud.fr>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/Documentation/networking/cxacru.txt b/Documentation/networking/cxacru.txt
new file mode 100644
index 0000000..b074681
--- /dev/null
+++ b/Documentation/networking/cxacru.txt
@@ -0,0 +1,84 @@
+Firmware is required for this device: http://accessrunner.sourceforge.net/
+
+While it is capable of managing/maintaining the ADSL connection without the
+module loaded, the device will sometimes stop responding after unloading the
+driver and it is necessary to unplug/remove power to the device to fix this.
+
+Detected devices will appear as ATM devices named "cxacru". In /sys/class/atm/
+these are directories named cxacruN where N is the device number. A symlink
+named device points to the USB interface device's directory which contains
+several sysfs attribute files for retrieving device statistics:
+
+* adsl_controller_version
+
+* adsl_headend
+* adsl_headend_environment
+ Information about the remote headend.
+
+* downstream_attenuation (dB)
+* downstream_bits_per_frame
+* downstream_rate (kbps)
+* downstream_snr_margin (dB)
+ Downstream stats.
+
+* upstream_attenuation (dB)
+* upstream_bits_per_frame
+* upstream_rate (kbps)
+* upstream_snr_margin (dB)
+* transmitter_power (dBm/Hz)
+ Upstream stats.
+
+* downstream_crc_errors
+* downstream_fec_errors
+* downstream_hec_errors
+* upstream_crc_errors
+* upstream_fec_errors
+* upstream_hec_errors
+ Error counts.
+
+* line_startable
+ Indicates that ADSL support on the device
+ is/can be enabled, see adsl_start.
+
+* line_status
+ "initialising"
+ "down"
+ "attempting to activate"
+ "training"
+ "channel analysis"
+ "exchange"
+ "waiting"
+ "up"
+
+ Changes between "down" and "attempting to activate"
+ if there is no signal.
+
+* link_status
+ "not connected"
+ "connected"
+ "lost"
+
+* mac_address
+
+* modulation
+ "ANSI T1.413"
+ "ITU-T G.992.1 (G.DMT)"
+ "ITU-T G.992.2 (G.LITE)"
+
+* startup_attempts
+ Count of total attempts to initialise ADSL.
+
+To enable/disable ADSL, the following can be written to the adsl_state file:
+ "start"
+ "stop
+ "restart" (stops, waits 1.5s, then starts)
+ "poll" (used to resume status polling if it was disabled due to failure)
+
+Changes in adsl/line state are reported via kernel log messages:
+ [4942145.150704] ATM dev 0: ADSL state: running
+ [4942243.663766] ATM dev 0: ADSL line: down
+ [4942249.665075] ATM dev 0: ADSL line: attempting to activate
+ [4942253.654954] ATM dev 0: ADSL line: training
+ [4942255.666387] ATM dev 0: ADSL line: channel analysis
+ [4942259.656262] ATM dev 0: ADSL line: exchange
+ [2635357.696901] ATM dev 0: ADSL line: up (8128 kb/s down | 832 kb/s up)