From mboxrd@z Thu Jan  1 00:00:00 1970
From: Alexander Varnin <fenixk19@mail.ru>
Subject: Need help adding platform UIO devices to board
Date: Wed, 28 Nov 2012 22:53:23 +0400
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Hello!
I'm trying to add UIO device to my system to handle interrupt. But i'm
facing following problem. Docs says, on reading device /dev/uio0 it will
block until interrupt occurs. I've made simple program for test. It
tries to write 1 to enable interrupts.

    #include <unistd.h>
    #include <errno.h>
    #include <fcntl.h>
    #include <stdio.h>

    int main()
    {
        int fd;
        char c = 1;
        fd = open("/dev/uio0", O_RDONLY);
        if (fd<0) {
            printf("open error: %d\n", errno);
             return 0;
        }
        printf("fd == %d\n", fd);
        int res = write(fd, &c, 1);
        if(res<0) {
            printf("write error: %d\n", errno);
        }
        return 0;
    }

And as the output i get

    fd ==
    3                                                                        

    write error: 9 

error 9 means "bad file descriptor". File /dev/uio0 is here.
/sys/class/uio/uio0 folder i also. Reading are fails the same way.

Here is how i add device to the system in board specific code

    static struct uio_info cross_uio_info = {
       .name = "uio_mcross",
       .version = "0.1",
       .irq = IRQ_EINT14,
       .irq_flags = 0,
    };

    static struct platform_device minipos_cross_device = {
        .name          = "uio_pdrv_genirq",
        .id          = -1,
        .dev              = {
          .platform_data = &cross_uio_info,
        }
    };

and then add platform device.
Please, help.