Kontron KTAM3874-pITX - Manual (Page 64)

KTD-S0057-I Page 60 Linux® Programming Examples (DebianTM)
KTAM3874/pITX Software Guide
10.6 GPIO Example
An easy way to design an application with GPIO access consists in use of the sysfs interface. The directory
/sys/class/gpio contains the following entries:
export
gpiochip0 TI ® AM3874 SoC 32 GPIOs
gpiochip32 TI ® AM3874 SoC 32 GPIOs
gpiochip64 TI ® AM3874 SoC 32 GPIOs
gpiochip96 TI ® AM3874 SoC 32 GPIOs
gpiochip128 PMU 9 GPIOs
unexport
ATTENTION
Do not use other GPIO pins as are described in
the User's Guide chapter 'Digital I/O Interface'.
The kernel occupies some GPIO pins but not all are declared (for example GP1[0] and GP1[1] comprise the
first CAN bus interface). The command line below shows incomplete information (debugfs is already
mounted):
# cat /sys/kernel/debug/gpio
GPIOs 0-31, gpio:
GPIOs 32-63, gpio:
gpio-38 (mmc_cd ) in lo irq-198 edge-both
GPIOs 64-95, gpio:
GPIOs 96-127, gpio:
gpio-111 (PWR_RS485 ) out hi
gpio-112 (EN_RS485 ) out lo
gpio-113 (HALF_DUPLEX ) out lo
GPIOs 128-136, i2c/1-002d, tps65911, can sleep:
gpio-129 (tps65910:led1 ) out lo
gpio-131 (tps65910:led2 ) out lo
Further information about GPIO programming is available on
https://www.kernel.org/doc/Documentation/
gpio.txt