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This adds some sysfs entries to provide userspace control of the
four-element LED "lightbar" on the Chromebook Pixel. This only instantiates
the lightbar controls if the device actually exists.
To prevent DoS attacks, this interface is limited to 20 accesses/second,
although that rate can be adjusted by a privileged user.
On Chromebooks without a lightbar, this should have no effect. On the
Chromebook Pixel, you should be able to do things like this:
$ cd /sys/devices/virtual/chromeos/cros_ec/lightbar
$ echo 0x80 > brightness
$ echo 255 > brightness
$
$ cat sequence
S0
$ echo konami > sequence
$ cat sequence
KONAMI
$
$ cat sequence
S0
And
$ cd /sys/devices/virtual/chromeos/cros_ec/lightbar
$ echo stop > sequence
$ echo "4 255 255 255" > led_rgb
$ echo "0 255 0 0 1 0 255 0 2 0 0 255 3 255 255 0" > led_rgb
$ echo run > sequence
Test the DoS prevention with this:
$ cd /sys/devices/virtual/chromeos/cros_ec/lightbar
$ echo 500 > interval_msec
$ time (cat version version version version version version version)
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-by: Olof Johansson <olofj@chromium.org>
Tested-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: Benson Leung <bleung@chromium.org>
Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Tested-by: Gwendal Grignou <gwendal@chromium.org>
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
Signed-off-by: Olof Johansson <olof@lixom.net>
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| chrome | ||
| goldfish | ||
| olpc | ||
| x86 | ||
| Kconfig | ||
| Makefile | ||