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Date: Tue, 20 Mar 2012 22:48:25 +0400
Subject: Re: uio_pci_generic driver
From: tochansky@tochlab.net
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: linux-kernel@vger.kernel.org
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> On Tue, Mar 20, 2012 at 09:56:03PM +0400, tochansky@tochlab.net wrote:
>> Hello!
>> I have a question about uio_pci_generic driver. I'm trying to use it in
>> my
>> project, but have no luck.
>> There are very little information on the subject. If you have a few
>> minutes, I would like to ask a few questions.
>> I need to mmap() memory of my board to work with it. I did
>> # modprobe uio_pci_generic
>> # echo "xxxx xxxx" > /sys/bus/pci/drivers/uio_pci_generic/new_id
>>
>> Files in /sys/class/uio/uio0 appears, but there no directory named
>> /sys/class/uio/uio0/maps/.
>> Anyway I tryed to mmap with code:
>>
>> #include <sys/types.h>
>> #include <sys/stat.h>
>> #include <fcntl.h>
>>
>> #include <sys/mman.h>
>> #include <stdio.h>
>>
>> int main()
>> {
>>         int fd = open("/dev/uio0", O_RDWR | O_SYNC);
>>         printf("fd = %d\n", fd);
>>         void *addr = mmap(NULL, 1024, PROT_READ, MAP_SHARED, fd, 0);
>>         printf("addr = %p\n", addr);
>> }
>>
>> Ofcourse, mmap() failes with error "Invalid argument". Nothing criminal
>> in
>> dmesg and any other hints of error.
>>
>> --
>> Dmitriy
>
>
> Map memory through /sys/bus/pci/devices/......
>
> Also copy questions to mailing lists please.
>
Thanks, it works now.

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#include <sys/mman.h>
#include <stdio.h>

int main() {
        int fd =
open("/sys/class/pci_bus/0000:03/device/0000:03:00.0/resource5",
O_RDWR | O_SYNC);
        printf("fd = %d\n", fd);
        void *addr = mmap(NULL, 512, PROT_READ, MAP_SHARED, fd, 0);
        if(addr == MAP_FAILED)  {
                perror("mmap");
        }
        else {
                printf("addr = %p\n", addr);
        }
}

May be its time to add some hints in documentation? :-)