There is 'qca_mux_ctl' utility that can configure GPIO pinmux settings. It is included in default 8devices firmware image. Config is saved in /etc/qca_mux_conf.json file and applied by running qca_mux_ctl command.
/etc/qca_mux_conf.json
{
"mux_list": [
{"gpio" : 21, "signal_direction": "IN", "gpio_direction" : "IN","signal": "UART1_RD"},
{"gpio" : 22, "signal_direction": "OUT", "gpio_direction" : "OUT","signal": "UART1_TD"}
],
"functions": [
]
}
Serial port is available at /dev/ttyATH0
Quick test: echo AAAA > /dev/ttyATH0
Terminal:
opkg update opkg install picocom picocom -b 115200 /dev/ttyATH0
/etc/qca_mux_conf.json
{
"mux_list": [
{"gpio" : 21, "signal_direction": "IN", "gpio_direction" : "OUT","signal": "I2C_DATA"},
{"gpio" : 21, "signal_direction": "OUT", "gpio_direction" : "OUT","signal": "I2C_DATA"},
{"gpio" : 22, "signal_direction": "OUT", "gpio_direction" : "OUT","signal": "I2C_CLK"}
],
"functions": [
]
}