GPIOs in the userspace (for FPGA programming)

Andrés Calderón andres.calderon at emqbit.com
Mon Mar 15 08:58:14 EDT 2010


Hi,

Simple sample project for GPIO usage in the user space:

svn --username anonymous  co
https://www.emqbit.net/svnrepos/embedded/XBurst/gpio
pass: <just enter>

BR,

    Andrés Calderón
    Cel:     +57 (300) 275 3666
    Email: andres.calderon at emqbit.com
    Gtalk:  andresfcalderon at gmail.com
    Web:    www.emqbit.com







On Sat, Mar 13, 2010 at 10:08 AM, Bas Wijnen <wijnen at debian.org> wrote:
> On Sat, Mar 13, 2010 at 08:08:55AM -0500, Carlos Camargo wrote:
>> We've already used a similar code, but, we use 0xB0010000 as GPIO_BASE,
>> searchig on dingoo sample code, we found that  they (and you) change this
>> address to 0x001000, can you tell me why ?
>
> The Mips has a special meaning for the highest address bit: if it's set,
> the address will generate an address fault unless running in kernel
> mode.
>
> Since this program is running in user mode, it cannot map anything to an
> address above 0x80000000, because it would generate an address fault to
> access it.
>
> The kernel uses the unpaged (directly accessible) kseg1, which goes from
> 0xa0000000 to 0xc0000000 and is unaccessible from user mode (because the
> upper address bit is set).
>
> Thanks,
> Bas
>
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