[Gllug] Virtual memory error in driver

[salsaman at xs4all.nl]

On Tue, July 26, 2011 13:53, James Courtier-Dutton wrote:
> On 26 July 2011 12:37,  <salsaman at xs4all.nl> wrote:
>> On Tue, July 26, 2011 11:02, James Courtier-Dutton wrote:
>>> On 25 July 2011 22:14,  <salsaman at xs4all.nl> wrote:
>>>> Hi all,
>>>> I am trying to write a driver to read the values of some peripheral.
>>>> The
>>>> first step is to set the direction of the pins to read, the code is
>>>> something like:
>>>>
>>>> unit8_t *address = 0x01e26088;
>>>> memset(address, 0xFF, 1);
>>>>
>>>> however when I load the module with this code, I get an error:
>>>>
>>>> Unable to handle kernel paging request at virtual address 01e26088
>>>>
>>>
>>> Where are you getting 0x01e26088 from?
>>
>> It's from the data sheet, the pin direction register for the device.
>>
>> Salsaman.
>>
>
> Do you have a url where I could download the datasheet?
> What sort of platform is this? Is it Linux on x86?
>
> If it is a PCI device, that address will be relative to the PCI
> assigned resources range.
> The first thing your driver will have to do is "claim" the PCI resources.
> As an example look in the Linux kernel for:
> ca0106_main.c   (I wrote it)
>
> function:
> snd_ca0106_create
>
>
> Once your driver has claimed the PCI resources, it can then write to them.
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>


OK, I solved it in the end.

There is a macro IO_ADDRESS() which translates the virtual address to a
real value.

Then another macro __raw_writeb() to do the actual writing.


Regards,
Salsaman.


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