board: asus: transformer: add ASUS Transformer Pad TF701T support
The ASUS Transformer Pad TF701T is an Android tablet computer made by
ASUS, successor to the ASUS Transformer Pad Infinity. The tablet includes
a Tegra 4 T114 processor clocked at 1.9 GHz, and an upgraded 2560×1600
pixel resolution screen, increasing the pixel density to 300 PPI and
a mobile dock. Transformers (t114) board derives from Nvidia Macallan
development board.
Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
diff --git a/doc/board/asus/index.rst b/doc/board/asus/index.rst
index 2cac04c..a9ba7a5 100644
--- a/doc/board/asus/index.rst
+++ b/doc/board/asus/index.rst
@@ -9,3 +9,4 @@
grouper
transformer_t20
transformer_t30
+ transformer_t114
diff --git a/doc/board/asus/transformer_t114.rst b/doc/board/asus/transformer_t114.rst
new file mode 100644
index 0000000..3e42b5d
--- /dev/null
+++ b/doc/board/asus/transformer_t114.rst
@@ -0,0 +1,74 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+U-Boot for the ASUS Transformer device family
+=============================================
+
+Quick Start
+-----------
+
+- Build U-Boot
+- Boot U-Boot by loading it into RAM (coldboot)
+- Chainloading U-Boot from the vendor bootloader
+- Boot
+
+Build U-Boot
+------------
+
+U-Boot can be built in two forms: U-Boot with SPL, which is used for booting
+by loading directly into RAM and U-Boot without SPL, which can be flashed
+and chainloaded from the vendor bootloader.
+
+To build U-Boot with SPL proseed:
+
+.. code-block:: bash
+
+ $ export CROSS_COMPILE=arm-none-eabi-
+ $ make tf701t_defconfig
+ $ make
+
+After the build succeeds, you will obtain the final ``u-boot-dtb-tegra.bin``
+file, ready for cold booting by loading into RAM.
+
+To build U-Boot without SPL adjust tf701t_defconfig:
+
+.. code-block::
+
+ CONFIG_TEXT_BASE=0x80A00000
+ CONFIG_SKIP_LOWLEVEL_INIT=y
+ # CONFIG_OF_BOARD_SETUP is not set
+ CONFIG_TEGRA_SUPPORT_NON_SECURE=y
+
+After the build succeeds, you will obtain the final ``u-boot-dtb.bin`` file,
+ready for booting with fastboot boot or which can be further processed into
+a flashable boot.img.
+
+Boot U-Boot by loading it into RAM (coldboot)
+---------------------------------------------
+
+Done fairly simply by using fusee-tools (using run_bootloader.sh) and placing
+``u-boot-dtb-tegra.bin`` generated on the previous step into fusee-tools dir.
+This method requires constant access to the host PC or payloader and can fully
+eliminate influence of the vendor bootloader onto the boot process.
+
+.. code-block:: bash
+
+ $ ./run_bootloader.sh -s T114 -t ./bct/tf701t.bct
+
+Chainloading U-Boot from the vendor bootloader
+----------------------------------------------
+
+``u-boot-dtb.bin`` has to be further packed into Android boot image form,
+where ``u-boot-dtb.bin`` acts as kernel, while dtb and ramdisk parts should
+not be included. Then the generated boot image can be flashed into the /boot
+partition of the tablet using vendor bootloader's fastboot and will act as
+the bootloader of the last stage.
+
+Boot
+----
+In both cases after U-Boot obtains control it performs search of extlinux.conf
+first on the dock USB device is available, then on MicroSD card if available
+and lastly on eMMC. If none of the devices above are present, then the device
+is turned off.
+
+If during boot of U-Boot Volume Down button is pressed, the device will enter
+U-Boot bootmenu.