FYI I have just released v1.3.5 of the diozero Java library that includes support for Rockchip RK3399 SoCs - i.e. the Rock 4 family. I have done all my testing on a recently acquired Rock 4C+.
This implementation includes support for high-speed memory mapped GPIO control as well as input event detection using gpio chardev.
I hope some of you find this useful. Please reach out via GitHub if you have any questions, comments or feedback.
Output from running the GpioReadAll utility application:
$ sudo java -cp diozero-sampleapps-1.3.5.jar com.diozero.sampleapps.GpioReadAll
Header: Default
+-----+----------+------+---+--------+----------+--------+---+------+----------+-----+
+ GP# + Name + Mode + V + gpiod + Physical + gpiod + V + Mode + Name + GP# +
+-----+----------+------+---+--------+----------+--------+---+------+----------+-----+
| | 3v3 | | | | 1 || 2 | | | | 5v | |
| 71 | GPIO2_A7 | In | 1 | 2:7 | 3 || 4 | | | | 5v | |
| 72 | GPIO2_B0 | In | 1 | 2:8 | 5 || 6 | | | | GND | |
| 75 | GPIO2_B3 | In | 1 | 2:11 | 7 || 8 | 4:20 | 1 | UART | TXD2 | 148 |
| | GND | | | | 9 || 10 | 4:19 | 1 | UART | RXD2 | 147 |
| 146 | PWM0 | In | 0 | 4:18 | 11 || 12 | 4:3 | 1 | In | GPIO4_A3 | 131 |
| 150 | PWM1 | In | 0 | 4:22 | 13 || 14 | | | | GND | |
| 149 | GPIO4_C5 | In | 0 | 4:21 | 15 || 16 | 4:26 | 0 | In | GPIO4_D2 | 154 |
| | 3v3 | | | | 17 || 18 | 4:28 | 0 | In | GPIO4_D4 | 156 |
| 40 | SPI1_TX | SPI | 0 | 1:8 | 19 || 20 | | | | GND | |
| 39 | SPI1_RX | SPI | 1 | 1:7 | 21 || 22 | 4:29 | 0 | In | GPIO4_D5 | 157 |
| 41 | SPI1_CLK | SPI | 0 | 1:9 | 23 || 24 | 1:10 | 1 | SPI | SPI1_CS0 | 42 |
| | GND | | | | 25 || 26 | | | In | ADC_IN0 | 0 |
| 64 | GPIO2_A0 | In | 1 | 2:0 | 27 || 28 | 2:1 | 1 | In | GPIO2_A1 | 65 |
| 74 | GPIO2_B2 | In | 1 | 2:10 | 29 || 30 | | | | GND | |
| 73 | GPIO2_B1 | In | 1 | 2:9 | 31 || 32 | 3:0 | 1 | In | GPIO3_C0 | 112 |
| 76 | GPIO2_B4 | In | 1 | 2:12 | 33 || 34 | | | | GND | |
| 133 | GPIO4_A5 | In | 1 | 4:5 | 35 || 36 | 4:4 | 1 | In | GPIO4_A4 | 132 |
| 158 | GPIO4_D6 | In | 0 | 4:30 | 37 || 38 | 4:6 | 1 | In | GPIO4_A6 | 134 |
| | GND | | | | 39 || 40 | 4:7 | 1 | In | GPIO4_A7 | 135 |
+-----+----------+------+---+--------+----------+--------+---+------+----------+-----+