.. SPDX-License-Identifier: GPL-2.0+

U-Boot for the Samsung N1 device family
=======================================

``DISCLAMER!`` Moving your Samsung Galaxy R (GT-I9103) or Samsung Captivate Glide
(SGH-i927) to use U-Boot assumes replacement of the sboot. Vendor android firmwares
will no longer be able to run on the device. This replacement IS reversible.

Quick Start
-----------

- Build U-Boot
- Boot

Build U-Boot
------------

Device support is implemented by applying config fragment to a generic board
defconfig. Generic board defconfig is suitable for Samsung Galaxy R (GT-I9103)
while Samsung Captivate Glide (SGH-i927) support is provided by applying
``bose.config`` fragment.

.. code-block:: bash

    $ export CROSS_COMPILE=arm-none-eabi-
    $ make n1_defconfig bose.config # For Captivate Glide
    $ make

After the build succeeds, you will obtain the final ``u-boot-dtb-tegra.bin``
image, ready for further processing.

Boot
----

Currently, U-Boot can be preloaded into RAM via the NvFlash. To enter
RCM protocol use ``home`` and ``volume up`` for Galaxy R and ``volume down``
and ``volume up`` Captivate Glide key combination plus plugging usb in.
The host PC should recognize an APX device.

Built U-Boot ``u-boot-dtb-tegra.bin`` can be loaded from fusee-tools
directory with

.. code-block:: bash

    $ ./utils/nvflash_t20 --setbct --bct ./bct/i927.bct --configfile ./utils/flash.cfg --bl u-boot-dtb-tegra.bin --sbk (in form of 0xABCDABCD 4 times) --sync # For Captivate Glide

To boot Linux, U-Boot will look for an ``extlinux.conf`` on MicroSD and then on
eMMC. Additionally, if the Volume Down button is pressed while loading, the
device will enter bootmenu. Bootmenu contains entries to mount MicroSD and eMMC
as mass storage, fastboot, reboot, reboot RCM and poweroff.