Is it possible to read GPIO registers using devmem2 under Linux? (on DK2)

[ABora.1]

On DK2, using devmem2 on linux I read that GPIOH->MODER/ODR (0x50009000/0x50009014) are all zeroes. The same for GPIOA. OTOH some other things can be read out like RTC clock settings. Is there a way to read the GPIO registers?

[Olivier GALLIEN]

Hi @ABora.1​ ,

Please have a look to How to read or write peripheral registers - stm32mpu

You probably miss the step to enable the GPIO clock.

Olivier

[ABora.1]

I don't quite understand why those GPIO clocks are apparently off by default under Linux. U-Boot enables a bunch of them, does Linux turn them off again? How is the WiFi able to operate without GPIOH? To my understanding PH4 is used to drive the on/off wire for the WiFi module.

[Olivier GALLIEN]

Hi @ABora.1​ ,

Linux Clock framework manage clock dynamically and enable it only when required by drivers.

Olivier