AM5728: sysfs gpio not working

Hi Pat,

The first thing I doubt is the pinmux settings for GPIO. This is configured at the U-Boot stage in the file: board/ti/am57xx/mux_data.h

Also when you say 

Patrick Murphy said:

I can twiddle the gpio's using memory mapped io and it all works as expected.

With just the direct writes are you able to toggle the GPIOs and see that on the scope without having to configure the pinmux?

- Keerthy

I'll try to attach a copy of our mux_data.h file.

I have only tested with an image built using that mux data. But I can see the inputs and outputs on the scope in the expected state
when I read/write directly to them.

For an explicit example, I setup a small echo program to read input 2_3 and write to output 2_28. With polled memmapped io
I see the input change and write the output. All verified on the scope.

But when I export pins 67 and 92 in sysfs which and read/write those values I get NO change on the scope.

Just FYI, Here is the output from 'cat /sys/kernel/debug/gpio'

root@am57xx-evm:/sys/class/gpio# cat /sys/kernel/debug/gpio
gpiochip0: GPIOs 0-31, parent: platform/4ae10000.gpio, gpio-0-31:

gpiochip1: GPIOs 32-63, parent: platform/48055000.gpio, gpio-32-63:
gpio-40 ( |51000000.pcie ) out lo
gpio-62 ( |encoder ) out hi

gpiochip2: GPIOs 64-95, parent: platform/48057000.gpio, gpio-64-95:
gpio-67 ( |sysfs ) in lo IRQ
gpio-92 ( |sysfs ) in lo

gpiochip3: GPIOs 96-127, parent: platform/48059000.gpio, gpio-96-127:
gpio-117 ( |vbus ) in lo IRQ

gpiochip4: GPIOs 128-159, parent: platform/4805b000.gpio, gpio-128-159:

gpiochip5: GPIOs 160-191, parent: platform/4805d000.gpio, gpio-160-191:
gpio-187 ( |cd ) in lo IRQ

gpiochip6: GPIOs 192-223, parent: platform/48051000.gpio, gpio-192-223:
gpio-200 ( |beagle-x15:usr1 ) out hi
gpio-201 ( |beagle-x15:usr0 ) out lo
gpio-202 ( |encoder ) out hi
gpio-203 ( |vtt_fixed ) out hi
gpio-204 ( |encoder ) in lo IRQ
gpio-206 ( |beagle-x15:usr2 ) out lo
gpio-207 ( |beagle-x15:usr3 ) out lo

gpiochip7: GPIOs 224-255, parent: platform/48053000.gpio, gpio-224-255:

gpiochip8: GPIOs 504-511, parent: platform/48070000.i2c:tps659038@58:tps659038_gpio, 48070000.i2c:tps659038@58:tps659038_gpio, can sleep:
gpio-506 ( |gpio_fan ) out hi

7571.mux_data.h

Hi Pat,

Can you dump the GPIO2 Module registers when you do it via sysfs?

Also does the sysfs nodes show that the direction & levels are fine?

I mean:

cat /sys/class/gpio/gpio'x'/direction
cat /sys/class/gpio/gpio'x'/value.

Best Regards,
Keerthy

Hi Keerthy,

I think I found the main culprit for my initial problems. It seems the numbering of the pins for sysfs drop the first 32. For pin 2_3 I was exporting 67 (2 * 32 + 3) when I should have been exporting 35 (1 * 32 + 3). With pin 35 exported and rising edge interrupts setup, I can see input values (/sys/class/gpio/gpio35/value) change when I put 3.3 on that pin. 

Is this assumption correct? What do I do if I need to get to the first 32 pins? ( I don't think I need to right now, just curious).

thanks,

pat