ARM: tegra20: implement BCT patching

This function allows updating bootloader from u-boot
on production devices without need in host PC.

Be aware! It works only with re-crypt BCT.

Tested-by: Robert Eckelmann <longnoserob@gmail.com> # ASUS TF101 T20
Signed-off-by: Ramin Khonsari <raminterex@yahoo.com>
Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
Signed-off-by: Tom <twarren@nvidia.com>

doc/usage/cmd/ebtupdate.rst

@@ -0,0 +1,69 @@
+.. SPDX-License-Identifier: GPL-2.0+:
+
+ebtupdate command
+=============
+
+Synopsis
+--------
+
+::
+
+    ebtupdate [<bct> [<ebt>] [<size>]]
+
+Description
+-----------
+
+The "ebtupdate" command is used to self-update bootloader on Tegra 2 and Tegra 3
+production devices which were processed using re-cryption.
+
+The "ebtupdate" performs encryption of new bootloader and decryption, patching
+and re-encryption of BCT "in situ". After BCT and bootloader can be written in
+their respective places.
+
+bct
+    address of BCT block pre-loaded into RAM.
+
+ebt
+    address of the bootloader pre-loaded into RAM.
+
+size
+    size of the pre-loaded bootloader.
+
+Example
+-------
+
+This is the boot log of a LG Optimus Vu:
+
+::
+
+    => mmc dev 0 1
+    switch to partitions #1, OK
+    mmc0(part 1) is current device
+    => mmc read $kernel_addr_r 0 $boot_block_size
+    MMC read: dev # 0, block # 0, count 4096 ... 4096 blocks read: OK
+    => load mmc 0:1 $ramdisk_addr_r $bootloader_file
+    684783 bytes read in 44 ms (14.8 MiB/s)
+    => size mmc 0:1 $bootloader_file
+    => ebtupdate $kernel_addr_r $ramdisk_addr_r $filesize
+    => mmc dev 0 1
+    switch to partitions #1, OK
+    mmc0(part 1) is current device
+    => mmc write $kernel_addr_r 0 $boot_block_size
+    MMC write: dev # 0, block # 0, count 4096 ... 4096 blocks written: OK
+    => mmc dev 0 2
+    switch to partitions #2, OK
+    mmc0(part 2) is current device
+    => mmc write $ramdisk_addr_r 0 $boot_block_size
+    MMC write: dev # 0, block # 0, count 4096 ... 4096 blocks written: OK
+
+Configuration
+-------------
+
+The ebtupdate command is only available if CONFIG_CMD_EBTUPDATE=y and
+only on Tegra 2 and Tegra 3 configurations.
+
+Return value
+------------
+
+The return value $? is set to 0 (true) if everything went successfully. If an
+error occurs, the return value $? is set to 1 (false).