Phytec i.MX 93 - Gpios

i.MX 93 BSP Manual PD24.1.1 Documentation Rev.: imx8mp-pd22.1.2-51-ga548be7d
7.5 GPIOs
The phyBOARD-Segin/Nash i.MX 93 doesn’t have a set of pins especially dedicated for user I/Os since all
GPIOs are used by kernel device drivers or used for a specic purpose. The processor has organized its
GPIOs into ve banks of 32 GPIOs each (GPIO1 – GPIO4) GPIOs. gpiochip0, gpiochip32, gpiochip64 and
gpiochip96 are the sysfs representation of these internal i.MX 93 GPIO banks GPIO1 – GPIO4.
The GPIOs are identied as GPIO<X>_<Y> (e.g. GPIO4_07). <X> identies the GPIO bank and
counts from 1 to 4, while <Y> stands for the GPIO within the bank. <Y> is being counted from 0 to 31
(32 GPIOs on each bank).
By contrast, the Linux kernel uses a single integer to enumerate all available GPIOs in the system. The
formula to calculate the right number is:
Linux GPIO number: <N> = (<X> - 1) * 32 + <Y>
Accessing GPIOs from userspace will be done using the libgpiod. It provides a library and tools for interacting
with the Linux GPIO character device. Examples of some usages of various tools:
• Detecting the gpiochips on the chip:
target:~$ gpiodetect
gpiochip0 [43810080.gpio] (32 lines)
gpiochip1 [43820080.gpio] (32 lines)
gpiochip2 [43830080.gpio] (32 lines)
gpiochip3 [47400080.gpio] (32 lines)
Note
Order of GPIOchips in i.MX 93 Application Processor Reference Manual and in Linux kernel dier!
GPIOchip address Linux Reference Manual
0x43810080 gpiochip0 gpiochip2
0x43820080 gpiochip1 gpiochip3
0x43830080 gpiochip2 gpiochip4
0x47400080 gpiochip3 gpiochip1
• Show detailed information about the gpiochips. Like their names, consumers, direction, active state,
and additional ags:
target:~$ gpioinfo gpiochip0
• Read the value of a GPIO (e.g GPIO 3 from chip0):
target:~$ gpioget gpiochip0 3
• Set the value of GPIO 3 on chip0 to 0 and exit tool:
target:~$ gpioset --mode=exit gpiochip0 3=0
• Help text of gpioset shows possible options:
target:~$ gpioset --help
Usage: gpioset [OPTIONS] <chip name/number> <offset1>=<value1> <offset2>=<value2> ...
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Accessing Peripherals 57