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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