This adds a new node for reboot modes on LEGO MINDSTORMS EV3. The EV3's
bootloader looks for a magic number in the ARM local RAM and if found,
it will boot into a special firmware update mode where the flash memory
can be written via USB.
This has been testing working using the command:
# systemctl reboot loader
Signed-off-by: David Lechner <david@xxxxxxxxxxxxxx>
---
arch/arm/boot/dts/da850-lego-ev3.dts | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/arch/arm/boot/dts/da850-lego-ev3.dts b/arch/arm/boot/dts/da850-lego-ev3.dts
index e4bbf48..1cb2ff1 100644
--- a/arch/arm/boot/dts/da850-lego-ev3.dts
+++ b/arch/arm/boot/dts/da850-lego-ev3.dts
@@ -212,6 +212,23 @@
compatible = "gpio-backlight";
gpios = <&gpio 44 GPIO_ACTIVE_HIGH>;
};
+
+ /* ARM local RAM */
+ memory@ffff0000 {
+ compatible = "syscon", "simple-mfd";
+ reg = <0xffff0000 0x2000>; /* 8k */
+
+ /*
+ * The I2C bootloader looks for this magic value to either
+ * boot normally or boot into a firmware update mode.
+ */
+ reboot-mode {
+ compatible = "syscon-reboot-mode";
+ offset = <0x1ffc>;
+ mode-normal = <0x00000000>;
+ mode-loader = <0x5555aaaa>;
+ };
+ };
};
&cpu {
--
2.7.4
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