video: implement framebuffer console

This patch realizes framebuffer console support for barebox. It
supports colors and enough escape sequences to show the barebox
console and editor properly.

fbconsole mini-HOWTO
====================

1. compile sandbox barebox with

    CONFIG_VIDEO=y
    CONFIG_FRAMEBUFFER_CONSOLE=y
    CONFIG_DRIVER_VIDEO_SDL=y

2. run barebox

3. test fbconsole

    fbconsole0.active=oe

Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 8 insertions, 0 deletions

diff --git a/Documentation/user/framebuffer.rst b/Documentation/user/framebuffer.rst
index 0065e7b42f..7d004fa1cf 100644
--- a/Documentation/user/framebuffer.rst
+++ b/Documentation/user/framebuffer.rst
@@ -41,3 +41,11 @@ A typical script to enable the framebuffer could look like this:
   # finally enable backlight
   gpio_direction_output 42 1
 
+Framebuffer console
+-------------------
+
+barebox has framebuffer console support which can be enabled with CONFIG_FRAMEBUFFER_CONSOLE.
+When registered each framebuffer device gets a corresponding fbconsole device. The console
+can be activated with ``fbconsolex.active=oe``. Depending on compile time options there are
+different fonts available. These can be selected with the fbconsolex.font variable. To get a
+list of fonts use ``devinfo fbconsolex``.