mb/system76/cml-u: Add Darter Pro 6 as a variant

Change-Id: I9ba7d2af3c9c298fda2b2997d52546cc2f702a82
Signed-off-by: Jeremy Soller <jeremy@system76.com>
Signed-off-by: Tim Crawford <tcrawford@system76.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52063
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

Documentation/mainboard/index.md

@@ -180,6 +180,7 @@ The boards in this section are not real mainboards, but emulators.
 
 ## System76
 
+- [Darter Pro 6](system76/darp6.md)
 - [Darter Pro 7](system76/darp7.md)
 - [Galago Pro 4](system76/galp4.md)
 - [Galago Pro 5](system76/galp5.md)

Documentation/mainboard/system76/darp6.md

@@ -0,0 +1,63 @@
+# System76 Darter Pro 6 (darp6)
+
+## Specs
+
+- CPU
+  - Intel Core i7-10510U
+  - Intel Core i5-10210U
+- EC
+  - ITE IT8587E running [System76 EC](https://github.com/system76/ec)
+- Graphics
+  - Intel UHD Graphics 620
+  - eDP 15.6" 1920x1080@60Hz LCD (LG LP156WFC-SPD3)
+- Memory
+  - Up to 64GB (2x32GB) dual-channel DDR4 SO-DIMMs @ 2666 MHz
+- Networking
+  - Gigabit Ethernet
+  - M.2 PCIe/CNVi WiFi/Bluetooth
+    - Intel Wi-Fi 6 AX200/AX201
+    - or Intel Wireless-AC 9560
+- Power
+  - 65W (19V, 3.42A) AC barrel adapter
+    - Chicony A12-065N2A, using a C5 power cord
+  - 54.5Wh 4-cell Lithium-Ion battery
+- Sound
+  - Realtek ALC293 codec
+  - Internal speakers and microphone
+  - Combined 3.5mm headphone and microphone jack
+  - Combined 3.5mm microphone and S/PDIF jack
+  - HDMI, Mini DisplayPort, USB-C DisplayPort audio
+- Storage
+  - 1x M.2 PCIe NVMe or SATA SSD
+  - SD card reader
+- USB
+  - 1x USB Type-C with Thunderbolt 3
+  - 2x USB 3.0 Type-A
+  - 1x USB 2.0 Type-A
+- Dimensions
+  - 1.98cm x 36.04cm x 24.46cm, 1.6kg
+
+
+## Flashing coreboot
+
+```eval_rst
++---------------------+-----------------+
+| Type                | Value           |
++=====================+=================+
+| Socketed flash      | no              |
++---------------------+-----------------+
+| Vendor              | GigaDevice      |
++---------------------+-----------------+
+| Model               | GD25B127D       |
++---------------------+-----------------+
+| Size                | 16 MiB          |
++---------------------+-----------------+
+| Package             | SOIC-8          |
++---------------------+-----------------+
+| Internal flashing   | yes             |
++---------------------+-----------------+
+| External flashing   | yes             |
++---------------------+-----------------+
+```
+
+The flash chip (U26) is right of the DIMM slots.