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I am trying to control a LED on a custom board. I have written the device driver and successfully loaded it. I have created a device file in /dev directory with the correct major number. Then I wrote a program in user plane to control the LED on the board, but my ioctl is failing with error number as 2 (No such File or Directory), the file descriptor returned is 3. Below is the application in user space.

int main(int argc, char **argv)
{
    struct  s_LEDControl sLedControlParam;  
    int     ledNumber;
    int     command;
    int     fDDevice;
    int     ioctlReturn;

    ledNumber   = atoi(argv[1]);
    command     = atoi(argv[2]);

    /* Prepare the message to be sent to Kernel Space */
    sLedControlParam.led = ledNumber;
    sLedControlParam.cmd = command;

    /* Open the device */
    fDDevice = open("/dev/newdevice_drv", O_RDWR);

    if(fDDevice == -1)
    {
         printf("ERROR: Cannot open the device /dev/newdevice_drv\n");
         exit(0);
    }

    ioctlReturn = ioctl(fDDevice, c_controlLED1, &sLedControlParam);

    if(ioctlReturn != 0)
    {
         printf("ERROR: ioctl failed Reason:%s FD:%d\n", strerror(errno), fDDevice);
    }

    close(fDDevice);
    return 0;
}

Just to check if something was wrong with the file descriptor, I passed a dummy file descriptor to ioctl and I got the correct error number. I am new to linux and device drivers, any help would be appreciated.

The above C program is cross compiled to PPC environment.

Below is some part of the driver code

MODULE_LICENSE("XXX");
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_SUPPORTED_DEVICE("XXXX");

/** Assign device functions to file_operation structure */
struct file_operations fops= {
        .owner=THIS_MODULE,
        .open=device_open,
        .release=device_release,
        .read=device_read,
        .write=device_write,
        .unlocked_ioctl=device_ioctl,
        .llseek=NULL,
};

static int device_ioctl( struct inode *inode, struct file *filp, unsigned int cmd, unsigned long arg)
{
        enum e_FPGACommand e_cmd;
        e_cmd = (enum e_FPGACommand)cmd;

        printk("DEBUG: device_ioctl entered\n");

        switch(e_cmd)
        {
            case c_controlLED1: controlLED1_ioctl(arg);
            break;

            default: printk("ERROR: Invalid command %d\n", e_cmd);
                     return INVALID_IOCTL;
            break;
        }

        printk("DEBUG: device_ioctl exited\n");

        return OK;
}

static int controlLED1_ioctl(unsigned int arg)
{
    struct s_LEDControl *sLedControlParam;
    int result;

    sLedControlParam = (struct s_LEDControl *)kmalloc(sizeof(struct s_LEDControl), GFP_KERNEL);

    if(sLedControlParam == GLO_NULL)
    {
        printk("ERROR: Memory allocation failed in controlLED1_ioctl\n");
        return FAILURE_MEMORY_ALLOCATION;
    }

    result = copy_from_user(sLedControlParam, (struct s_LEDControl *)arg, sizeof(struct s_LEDControl));

    if(result > 0) 
    {
        printk("ERROR: copy_from_user in controlLED1_ioctl returned unfinished bytes\n");
        kfree(sLedControlParam);
        return FAILURE_COPY_FROM_USER;
    }

    if(sLedControlParam->cmd == On)
    {
        /* On - Do something */
    }

    return OK;
}

I can't see any error messages, when the device driver is loaded I get all the prints. When I try to run my application I can see that the device was opened and immediately closed but can't see any prints from my ioctl function.

4

1 回答 1

2

检查这个答案。

你有

static int device_ioctl( struct inode *inode, struct file *filp, unsigned int cmd, unsigned long arg)

但他说必须

static long device_ioctl(struct file *file, unsigned int cmd_in, unsigned long arg)

我还没有验证它，但也许它有帮助。我只是好奇，因为它以前从未见过 unlocked_ioctl。

于 2013-01-30T07:56:19.873 回答