Re: PageFault when I write in the Serial registers, MMU ?

Hi Nicolas,

On Wednesday 11 July 2007 17:39, Nicolas Mederle wrote:

Hi,

    I am porting linux on a custom board equipped with a PPC750, and I
will like to have some advices on the MMU. I used the powerpc arch, and
I built my device tree.
    I will like to know in which files we can configure the
authorizations access for the I/O registers. When I use the function
md_ppc.progress, I have a data access fault. I modified the head. S
files, for add the BAT config. But I think that it is not correct, and
that it is possible to do it elsewhere (platform_init?). Moreover the
kernel modify the MMU config, it removes the BATs, and configures the
Registers Segments. So, must I remake the configuration? Or is it
possible to indicate, at the beginning, which space is reserved for I/O?
    I studied several patch (sandpoint, PrPMC2800) but none configures
really the MMU for I/O registers. In the same way, I read several books,
but I am not able to have information that I seek, therefore I am really
blocked. I warmly thank you for the assistance which you will be able to
bring to me.

    Mapping :     0x0000 0000    ->  0x0FFF FFFF   :   RAM
                         0x2000 0000   ->   0x201F FFFF   :   ASIC (
UART, DMA, GPIO, PIC...)
                         0x8000 0000   ->   0x8FFF FFFF   :   PCI
                         0xF000 0000   ->   0xFFFF FFFF   :   Flash
    The kernel is load at 0x0, an the system is a Run In Memory.
Currently, I don't use the flash.

You should ioremap() the memory you want to access, and use the I/O access 
functions defined in asm/io.h. Don't forget to iounmap() once you're done.

Best regards,

Laurent Pinchart