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SubjectWrite USB Device Driver entry not called
Date
I am writing usb Device Driver for vendor specific Device for the kernel
2.6.8 ... When i have loaded my skelton usb driver
ioctl,read,probe,disconnect,release entry points are working fine but when i
issue write() returns as bad file descriptor.... even though i have open the
device file with S_IWUSR

The error message is comming vfs_wirte() function

if (!(file->f_mode & FMODE_WRITE))
return -EBADF;

It seems to be f_mode is not set with FMODE_WRITE

Can any one help me to fix this problem.... Thanks in Advance

Regards
Eshwar


The skelton driver is as follows and application code follows the driver
code...

Driver.c

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/usb.h>
#include <asm/uaccess.h>


/* Function prototypes */
static int otg_cli_open ( struct inode *inode, struct file *file);
/* Function prototypes */
static int otg_cli_open ( struct inode *inode, struct file *file);
static void otg_cli_disconnect( struct usb_interface *intf);
static int otg_cli_release ( struct inode *inode, struct file *file);
static ssize_t otg_cli_read (struct file *file, char *buffer, size_t count,
loff_t *ppos);
static ssize_t otg_cli_write (struct file *file, const char *buffer,
size_t count, loff_t *ppos);
static int otg_cli_probe( struct usb_interface *intf,
const struct usb_device_id *id);

static struct usb_device_id otg_device_id[] = {
{ USB_INTERFACE_INFO(USB_CLASS_VENDOR_SPEC, 0x00, 0xff) },
{},
};

struct usb_driver otg_cli_driver = {
.owner = THIS_MODULE,
.name = "xyz",
.probe = otg_cli_probe,
.disconnect = otg_cli_disconnect,
.id_table = otg_device_id,
};

static struct file_operations otg_cli_fops = {
.owner = THIS_MODULE,
.write = otg_cli_write,
.open = otg_cli_open,
.read = otg_cli_read,
.release = otg_cli_release,
};

static struct usb_class_driver otg_cli_class = {
.name = "xyz",
.fops = &otg_cli_fops,
};

static struct usb_class_driver otg_cli_class = {
.name = "moschip-otg",
.fops = &otg_cli_fops,
.mode = S_IRWXU | S_IRWXG | S_IRWXO | S_IFCHR,
.minor_base = 250,
};

static int otg_cli_ioctl ( struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{

printk("Eshwar: otg_cli_ioctl");
return 0;
}

static ssize_t otg_cli_read (struct file *file, char *buffer,
size_t count, loff_t *ppos)
{
printk("Eshwar: otg_cli_read");
return 0;
}

static ssize_t otg_cli_write (struct file *file, const char *buffer,
size_t count,loff_t *ppos)
{
printk("Eshwar: otg_cli_write");
return 0;
}

static int otg_cli_open ( struct inode *inode, struct file *file)
{
printk("Eshwar: otg_cli_open");
return 0;
}

static int otg_cli_release ( struct inode *inode, struct file *file)
{
printk("Eshwar: otg_cli_release");
return 0;
}

static int otg_cli_probe( struct usb_interface *intf,
const struct usb_device_id *id)
{

printk("Eshwar: otg_cli_probe\n");
return 0;
}

static void otg_cli_disconnect( struct usb_interface *intf)
{
printk("Eshwar: otg_cli_disconnect\n");
usb_deregister_dev (intf, &otg_cli_class);
}

static int __init otg_cli_init(void)
{
printk ("Eshwar: otg_cli_init\n");
/* register this driver with the USB subsystem */
usb_register(&otg_cli_driver);
return 0;
}

/* OTG cleanup module */
static void __exit otg_cli_exit(void)
{
usb_deregister(&otg_cli_driver);
}

module_init (otg_cli_init);
module_exit (otg_cli_exit);

app.c


int main(int argc, char *argv[])
{
int devfd;
char send[512];

memset(send,'a',512);

devfd = open("/dev/usb/dabusb10",O_APPEND | S_IRUSR| S_IWUSR );
if ( write(devfd,send,512) < 0) {
printf ("write Failed\n");
return -1;
}

return 0;

}

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