GPIOs¶
There are two different GPIO controllers that you might interact with on the Ten64 board:
-
The SoC GPIO controller, mainly for the control header (has both GPIO and GIC IRQs) and some status LEDs.
Note: SoC GPIOs may have limitations on current source/sink, different min/max voltages depending on the voltage domain, or lack ESD protection.
-
The PCA/TCA9534 GPIO expander (U39), used for control I/Os in its vicinity (SFP, LTE), as well as some with special requirements (HD activity LED).
See Control Header for how to access the named GPIO_ pins.
Table of GPIOs¶
| GPIO Controller | IC Pin | Linux GPIO number (>6.2, earlier) |
Default Direction | Purpose | Meaning of ‘0’ | Meaning of ‘1' | Notes |
|---|---|---|---|---|---|---|---|
| TCA9539 (U39) | 0 | 640 368 | Input | Lower SFP+ TXFAULT | No transmitter fault | Transmitter Fault | Has pull up. When using SFP managed mode, the Phylink system will control these GPIOs |
| TCA9539 (U39) | 1 | 641 369 | Output | Lower SFP+ TXDISABLE | SFP+ transmitter disabled | SFP+ transmitter enabled | Has pull up – if the pin is not driven as output it goes to 1, this pin may not be effective with direct connect (DAC) cables |
| TCA9539 (U39) | 2 | 642 370 | Input | Lower SFP+ PRESENT | Lower SFP present | Lower SFP not present | |
| TCA9539 (U39) | 3 | 643 371 | Input | Lower SFP+ LOS | Lower SFP lost signal | Lower SFP has signal | |
| TCA9539 (U39) | 4 | 644 372 | Input | Upper SFP+ TXFAULT | No transmitter fault | Transmitter Fault | Has pull up |
| TCA9539 (U39) | 5 | 645 373 | Output | Upper SFP+ TXDISABLE | SFP+ transmitter disabled | SFP+ transmitter enabled | Has pull up – if the pin is not driven as output it goes to 1, this pin may not be effective with direct connect (DAC) cables |
| TCA9539 (U39) | 6 | 646 374 | Input | Upper SFP+ PRESENT | Upper SFP present | Upper SFP not present | |
| TCA9539 (U39) | 7 | 647 375 | Input | Upper SFP+ LOS | Upper SFP lost signal | Upper SFP has signal | |
| TCA9539 (U39) | 8 | 648 376 | Output | Cellular Modem (M.2/B) RESET | |||
| TCA9539 (U39) | 9 | 649 377 | Output | Cellular Modem (M.2/B) POWER OFF | |||
| TCA9539 (U39) | 10 | 650 378 | Output | Cellular Modem (M.2/B) DISABLE | |||
| TCA9539 (U39) | 11 | 651 379 | Output | Cellular Modem (M.2/B) GNSS | |||
| TCA9539 (U39) | 12 | 652 380 | Output | I/O Panel "ADMIN" LED+ | LED off | LED on | Both 380 and 381 need to be set up as outputs. On some beta test boards the ADMIN LED is bi-color. |
| TCA9539 (U39) | 13 | 653 381 | Output | I/O Panel "ADMIN" LED- | Must be 0 for LED to function | Set as a "GPIO Hog" in the Ten64 device tree | |
| TCA9539 (U39) | 14 | 654 382 | Output | “User Switch” / P9 Header | P9 is pressed | P9 not pressed | |
| TCA9539 (U39) | 15 | 655 383 | Output | ATX Front Panel Hard Drive Activity LED | |||
| LS1088 GPIO2 | 17 | 561 465 | Input | ATX Power Down / Control Header PWR_BTN_N | Request Shutdown | Normal Function | When gpio-keys driver enabled, kernel will listen on this pin |
| LS1088 GPIO3 | 27 | 603 443 | Input | GPIO Header GPIO_A | |||
| LS1088 GPIO3 | 28 | 604 444 | Input | GPIO Header GPIO_B | |||
| LS1088 GPIO3 | 29 | 605 445 | Input | GPIO Header GPIO_C | |||
| LS1088 GPIO4 | 4 | 612 388 | Input | GPIO Header GPIO_D | |||
| LS1088 GPIO4 | 5 | 613 389 | Input | GPIO Header GPIO_E | |||
| LS1088 GPIO4 | 6 | 614 390 | Input | GPIO Header GPIO_F | |||
| LS1088 GPIO4 | 7 | 615 391 | Input | GPIO Header GPIO_G | |||
| LS1088 GPIO4 | 8 | 616 392 | Input | GPIO Header GPIO_H ("ADMIN" button) | |||
| LS1088 GPIO4 | 9 | 617 393 | Input | Interrupt from TCA9539 | |||
| LS1088 GPIO4 | 11 | 619 395 | Output | SFP+ Left Down (usually bound to lower port) | LED off | LED on | |
| LS1088 GPIO4 | 12 | 620 396 | Output | SFP+ Right Up (usually bound to upper port) | LED off | LED on | |
| LS1088 GPIO4 | 13 | 621 397 | Input | SD/SIM Tray Status | Tray Inserted/Present | Tray ejected |
Device Tree Paths for each controller¶
A change in Linux 6.2 meant that all the SoC GPIO numbers start at 512 with bus-attached (I2C or other) coming after.
| Controller | DT Path | Default Linux GPIO Base | Default Linux GPIO Base (before 6.2) | Number of GPIOs |
|---|---|---|---|---|
| TCA9539 | /soc/i2c@2000000/gpio@76 | 640 | 368 | 16 |
| LS1088 GPIO1 | /soc/gpio@2300000 | 512 | 480 | 32 |
| LS1088 GPIO2 | /soc/gpio@2310000 | 544 | 448 | 32 |
| LS1088 GPIO3 | /soc/gpio@2320000 | 576 | 416 | 32 |
| LS1088 GPIO4 | /soc/gpio@2330000 | 608 | 384 | 32 |
The base number of LS1088 GPIO4 (384) being lesser than LS1088 GPIO3 (416) before Linux 6.2 is not a typo.
Userspace GPIO Access Using libgpiod¶
libgpiod does not use the GPIO numbers listed above, instead it uses names for each GPIO chip along with a pin number within that chip.
| Controller | Chip Name | Number of GPIOs |
|---|---|---|
| LS1088 GPIO1 | gpiochip0 | 32 |
| LS1088 GPIO2 | gpiochip1 | 32 |
| LS1088 GPIO3 | gpiochip2 | 32 |
| LS1088 GPIO4 | gpiochip3 | 32 |
| TCA9539 | gpiochip4 | 16 |