.. SPDX-License-Identifier: GPL-2.0+
Summary
=======
The Kontron SMARC-sAL28 board is a TSN-enabled dual-core ARM A72
processor module with an on-chip 6-port TSN switch and a 3D GPU.
Quickstart
==========
Compile U-Boot
--------------
Configure and compile the binary::
$ make kontron_sl28_defconfig
$ CROSS_COMPILE=aarch64-linux-gnu make
Copy u-boot.rom to a TFTP server.
Install the bootloader on the board
-----------------------------------
Please note, this bootloader doesn't support the builtin watchdog (yet),
therefore you have to disable it, see below. Otherwise you'll end up in
the failsafe bootloader on every reset::
> tftp path/to/u-boot.rom
> sf probe 0
> sf update $fileaddr 0x210000 $filesize
The board is fully failsafe, you can't break anything. But because you've
disabled the builtin watchdog you might have to manually enter failsafe
mode by asserting the ``FORCE_RECOV#`` line during board reset.
Disable the builtin watchdog
----------------------------
- boot into the failsafe bootloader, either by asserting the
``FORCE_RECOV#`` line or if you still have the original bootloader
installed you can use the command::
> wdt dev cpld_watchdog@4a; wdt expire 1
- in the failsafe bootloader use the "sl28 nvm" command to disable
the automatic start of the builtin watchdog::
> sl28 nvm 0008
- power-cycle the board
Useful I2C tricks
=================
The board has a board management controller which is not supported in
u-boot (yet). But you can use the i2c command to access it.
- reset into failsafe bootloader::
> i2c mw 4a 5.1 0; i2c mw 4a 6.1 6b; i2c mw 4a 4.1 42
- read board management controller version::
> i2c md 4a 3.1 1
Non-volatile Board Configuration Bits
=====================================
The board has 16 configuration bits which are stored in the CPLD and are
non-volatile. These can be changed by the `sl28 nvm` command.
=== ===============================================================
Bit Description
=== ===============================================================
0 Power-on inhibit
1 Enable eMMC boot
2 Enable watchdog by default
3 Disable failsafe watchdog by default
4 Clock generator selection bit 0
5 Clock generator selection bit 1
6 Disable CPU SerDes clock #2 and PCIe-A clock output
7 Disable PCIe-B and PCIe-C clock output
8 Keep onboard PHYs in reset
9 Keep USB hub in reset
10 Keep eDP-to-LVDS converter in reset
11 Enable I2C stuck recovery on I2C PM and I2C GP busses
12 Enable automatic onboard PHY H/W reset
13 reserved
14 Used by the RCW to determine boot source
15 Used by the RCW to determine boot source
=== ===============================================================
Please note, that if the board is in failsafe mode, the bits will have the
factory defaults, ie. all bits are off.
Power-On Inhibit
----------------
If this is set, the board doesn't automatically turn on when power is
applied. Instead, the user has to either toggle the ``PWR_BTN#`` line or
use any other wake-up source such as RTC alarm or Wake-on-LAN.
eMMC Boot
---------
If this is set, the RCW will be fetched from the on-board eMMC at offset
1MiB. For further details, have a look at the `Reset Configuration Word
Documentation`_.
Watchdog
--------
By default, the CPLD watchdog is enabled in failsafe mode. Using bits 2 and
3, the user can change its mode or disable it altogether.
===== ===== ===============================
Bit 2 Bit 3 Description
===== ===== ===============================
0 0 Watchdog enabled, failsafe mode
0 1 Watchdog disabled
1 0 Watchdog enabled, failsafe mode
1 1 Watchdog enabled, normal mode
===== ===== ===============================
Clock Generator Select
----------------------
The board is prepared to supply different SerDes clock speeds. But for now,
only setting 0 is supported, otherwise the CPU will hang because the PLL
will not lock.
Clock Output Disable And Keep Devices In Reset
----------------------------------------------
To safe power, the user might disable different devices and clock output of
the board. It is not supported to disable the "CPU SerDes clock #2" for
now, otherwise the CPU will hang because the PLL will not lock.
Automatic reset of the onboard PHYs
-----------------------------------
By default, there is no hardware reset of the onboard PHY. This is because
for Wake-on-LAN, some registers have to retain their values. If you don't
use the WOL feature and a soft reset of the PHY is not enough you can
enable the hardware reset. The onboard PHY hardware reset follows the
power-on reset.
Further documentation
=====================
- `Vendor Documentation`_
- `Reset Configuration Word Documentation`_
.. _Reset Configuration Word Documentation: https://raw.githubusercontent.com/kontron/rcw-smarc-sal28/master/README.md
.. _Vendor Documentation: https://raw.githubusercontent.com/kontron/u-boot-smarc-sal28/master/board/kontron/sl28/README.md