docs: update marvell howto

Signed-off-by: Boris Glimcher <36732377+glimchb@users.noreply.github.com>

hardware/dh3/README.md

@@ -45,3 +45,47 @@ Run telegraf container:
 ```bash
 sudo docker run -d --restart=always --network=host -v ./telegraf.d/telegraf.conf:/etc/telegraf/telegraf.conf docker.io/library/telegraf:1.29
 ```
+
+## Marvell
+
+lspci
+
+```bash
+root@dh3:~# lspci | grep Cavium
+0003:01:00.0 Network controller: Cavium, Inc. Device b900
+```
+
+usb
+
+```bash
+root@dh3:~# lsusb | grep CP2105
+Bus 002 Device 005: ID 10c4:ea70 Silicon Labs CP2105 Dual UART Bridge
+```
+
+uart over usb
+
+```bash
+root@dh3:~# ls -l  /dev/ttyUSB*
+crw-rw---- 1 root dialout 188, 0 May 30 14:26 /dev/ttyUSB0
+crw-rw---- 1 root dialout 188, 1 May 28 02:14 /dev/ttyUSB1
+```
+
+CPU version
+
+```bash
+root@dh3:~# minicom -D /dev/ttyUSB0
+
+root@ubuntu-server:~# head -n 2 /etc/os-release
+NAME="Ubuntu"
+VERSION="20.04 LTS (Focal Fossa)"
+```
+
+IMC version
+
+```bash
+root@dh3:~# minicom -D /dev/ttyUSB0
+
+uart:~$ version
+Version 1.05
+Built at 2023-09-27T15:19:47 Wednesday local time against board cn103_pcie_crb
+```