L4Re GPIO

Adam Lackorzynski adam at os.inf.tu-dresden.de
Sun Dec 21 23:36:11 CET 2014


On Tue Dec 16, 2014 at 16:01:02 +0700, Erry Pradana Darajati wrote:
> 1. I want to QEMU to accept input from keyboard to emulate and study how to
> use an configure of IO. I study this as a part of my main goal to access
> GPIOs of Pandaboard. Well, in my last email i stated that i already include
> x86-legacy.devs module in modules.list, and define
> REQUIRES_LIBS=libc_be_file_stdin, and using "default-kernel fiasco
> -serial_esc" defined. But, it still not respond to any of my keyboard
> input. So, what did i miss?

The x86-legacy.devs is for x86-based platforms. The pandaboard is ARM
based, so you do not need that file there. Also, the input here is also
based on the UART that is driven by the kernel, so there's no driver
necessary in user-land here. As already questioned in the other mail,
how are you trying to get the input in your program?

> 2. I have modified omap3 driver that included in the package to be used
> with omap4460 registers, but i have a few difficulties. There are few
> missing registers (like Clr_irq_enable1 register that not present in
> OMAP4460) and i am still cannot comprehend the scm_offset table. Because
> when i crossreferencing the source with the OMAP3 TRM the i cannot
> understand the value. My question is. Is it be able to use only some of the
> defined register to do simple IO task, and enable or disable register ?

I've not written the particular code, but the scm_offset seems to select
a specific gpio block.
For starting to work on a driver I recommend to start with a simple
program and directly work on the MMIO. This helps to understand how the
device is working. When basic things work, such as switching pins
on/off, settings directions, interrupts, etc things can be integrated.



Adam
-- 
Adam                 adam at os.inf.tu-dresden.de
  Lackorzynski         http://os.inf.tu-dresden.de/~adam/



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