Mini2440 GPIO Again

Hi all. I have been configuring and compiling kernels to get
/sys/class/gpio without success. I'm starting a new thread since I have
exhausted the existing ones and they mostly have 3 year old comments.

I have read all the postings and set all the config options. gpio does not
show up. I'm looking for any advice, like is there something that might be
blocking this?

Linux FriendlyARM source and .config is for W35i. Tools 4.4.3

Compiler output has lots of gpio related object files and nothing called
sysfs_gpio or similar - don't know if it should.

I need to get this working (or extend leds.c to include pins 0 and 1 or

Have you enabled sys filesystem (somewhere in the kernel config)?
Did you get other /sys/class entries?

I think CONFIG_GPIO_SYSFS is the one.

I see the Pengutronix BSP also has:




There are others.

I enabled all the GPIO options in config including one for sysfs gpio. It
is in Device Drivers, GPIO support, and called /sys/class/gpio... (sysfs
/sys/class has lots. BDI, BLOCK, FIRMWARE, I2C-dev, leds, spi-master, etc.

The .config has 5 or 6 gpio related items set to yes, including the sysfs.

Dave Festing
Attachment: (10.63 KB)
I was referring to Linux kernel 3.7 this may not help you a lot, trying to
get to work.

Attached find a config for that was floating around the net by
Eric Brombaugh.

Got it going. I was using a command line with an error (up arrow failure)
and copying an old zImage instead of my new uImage to SD every time.

SO it works. Unfortunately, GPB0 on the GPIO header is also the piezo
buzzer and my simplest test script just turns the buzzer on and off.
Apparently not disabling the timer/PWM on that pin. 

GPB1 not responding so back to the schematic.