Documentation: Add Topton N100 (X2F)

Document the board and how to flash coreboot.

Change-Id: Id585b064054b338ea8cead6edb6c5153030b9cde
Signed-off-by: Alicja Michalska <alicja.michalska@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/85680
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nicholas Chin <nic.c3.14@gmail.com>

Documentation/mainboard/index.md

@@ -408,6 +408,13 @@ Serval Workstation 13 <system76/serw13.md>
 Beaglebone Black <ti/beaglebone-black.md>
 ```
 
+## Topton
+```{toctree}
+:maxdepth: 1
+
+X2F-N100 <topton/adl/x2f-n100.md>
+```
+
 ## UP
 
 ```{toctree}

Documentation/mainboard/topton/adl/x2f-n100.md

@@ -0,0 +1,101 @@
+# Topton N100 (X2F)2 Firewall Appliance
+
+This page describes how to run coreboot on the Topton N100.
+
+```{eval-rst}
++---------------+---------------------------------+----------------------+
+| Binary file   | Apply                           | Required / Optional  |
++===============+=================================+======================+
+| IFD           | Intel Flash Descriptor          | Required (see below) |
++---------------+---------------------------------+----------------------+
+| ME            | Intel Management Engine         | Required (see below) |
++---------------+---------------------------------+----------------------+
+| FSP-M & FSP-S | Intel Firmware Support Package  | Required             |
++---------------+---------------------------------+----------------------+
+```
+
+## Flashing coreboot
+
+**WARNING:** There are multiple devices from the same vendor with
+similar name, using different board layout, capabilities and EC/SuperIO.
+
+Likewise, there are other vendors selling their devices with
+the same mainboard. According to the sticker on the box: `H30W-N100-226`.
+
+Please **DO NOT cross-flash firmware on "similar-looking" device**.
+Doing so **may kill your device**. You have been warned :)
+
+### Internally
+
+Vendor of this motherboard hasn't locked any flash regions, resulting
+in [flashprog] having full access to the SPI chip.
+Assuming that user had booted Linux with `iomem=relaxed`, they can:
+- Flash coreboot from stock firmware
+- Flash stock firmware from coreboot
+- Update coreboot build to a newer version
+
+	Without opening the case and connecting the SPI flasher.
+
+Please note that for AlderLake-N platform you will need to use
+[flashprog] v1.3.0 or newer.
+
+[flashrom] is broken due to regressions, which results in
+failed flashes, bricking the device.
+
+[flashprog] is a better maintained fork of [flashrom], which
+works flawlessly.
+
+You can skip extracting `SI_BIOS` and `SI_ME` regions from your ROM
+and flash coreboot to `SI_BIOS` region by issuing the following command:
+`flashprog -p internal --ifd -i SI_BIOS -w ./build/coreboot.rom`
+
+### Externally
+
+SPI chip on this mainboard is located near the SoC, on the other side
+of the board (upper-right corner).
+Please note that SPI voltage on this board is standard 3.3V, despite
+using mobile SoC.
+Vendor populated this board with Winbond W25Q128JV chip in SOIC-8 package.
+
+## Functionality
+
+### Tested and working
+
+- All USB ports (including mPCIe)
+- All NICs (4x Intel I226-V 2.5GbE)
+- All display outputs (HDMI, DisplayPort)
+- M.2 NVME (PCIe x2 electrically)
+- mPCIe WiFi
+- SATA port
+- Intel PTT (fTPM 2.0)
+- PC Speaker (goes beep-boop)
+- Serial console on the front of the device (RS232 in RJ45 form-factor),
+"Cisco-style"
+- PCIe passtrough (NICs to VMs, such as OpenWrt using libvirt)
+
+- Payload: EDK2, LinuxBoot
+- OS: Alpine Linux, Windows 11
+
+### Untested, broken
+
+- 5G modem on special M.2-like connector (lack hardware for it).
+- Suspend in Windows 11
+(might work, but Windows has been tested from USB drive).
+
+## Specification
+```{eval-rst}
++--------+-------------------------------+
+| SoC    | Intel AlderLake N100 (IoT)    |
++--------+-------------------------------+
+| Memory | DDR5 SO-DIMM (single-channel) |
++--------+-------------------------------+
+| EC     | ITE IT8625E                   |
++--------+-------------------------------+
+| SPI    | Winbond W25Q128 (16MiB 3.3V)  |
++--------+-------------------------------+
+| NIC    | 4x Intel I226-V (2.5GbE)      |
++--------+-------------------------------+
+```
+
+[flashprog]: https://flashprog.org/wiki/Flashprog
+[flashrom]: https://flashrom.org/Flashrom