[PATCH] Braille screen reader documentation

[Samuel Thibault <samuel.thibault@ens-lyon.org>]

Document the console=brl option and the usage of the braille screen
reader.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>

--- linux-2.6.24.1-orig/Documentation/kernel-parameters.txt	2008-01-25 09:31:45.000000000 +0100
+++ linux-2.6.24.1-perso/Documentation/kernel-parameters.txt	2008-02-23 13:21:27.000000000 +0100
@@ -463,6 +463,11 @@
 			switching to the matching ttyS device later.  The
 			options are the same as for ttyS, above.
 
+                If the device connected to the port is not a TTY but a braille
+                device, prepend "brl," before the device type, for instance
+			console=brl,ttyS0
+		For now, only VisioBraille is supported.
+
 	earlycon=	[KNL] Output early console device and options.
 		uart[8250],io,<addr>[,options]
 		uart[8250],mmio,<addr>[,options]
--- linux-2.6.24.1-orig/Documentation/braille-console.txt	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.24.1-perso/Documentation/braille-console.txt	2008-02-23 13:20:31.000000000 +0100
@@ -0,0 +1,34 @@
+                       Linux Braille Console
+
+To get early boot messages on a braille device (before userspace screen
+readers can start), you first need to compile the support for the usual serial
+console (see serial-console.txt), and for braille device (in Device Drivers -
+Accessibility).
+
+Then you need to specify a console=brl, option on the kernel command line, the
+format is:
+
+	console=brl,serial_options...
+
+where serial_options... are the same as described in serial-console.txt
+
+So for instance you can use console=brl,ttyS0 if the braille device is connected
+to the first serial port, and console=brl,ttyS0,115200 to override the baud rate
+to 115200, etc.
+
+By default, the braille device will just show the last kernel message (console
+mode).  To review previous messages, press the Insert key to switch to the VT
+review mode.  In review mode, the arrow keys permit to browse in the VT content,
+page up/down keys go at the top/bottom of the screen, and the home key goes back
+to the cursor, hence providing very basic screen reviewing facility.
+
+Sound feedback can be obtained by adding the braille_console.sound=1 kernel
+parameter.
+
+For simplicity, only one braille console can be enabled, other uses of
+console=brl,... will be discarded.  Also note that it does not interfere with
+the console selection mecanism described in serial-console.txt
+
+For now, only the VisioBraille device is supported.
+
+Samuel Thibault <samuel.thibault@ens-lyon.org>