Am Freitag, 1. Juli 2005 07:42 schrieb oujin.rera:
> Hi
>
> I have a very basic question.
>
> I have written a Kernel driver for an USB device. Now I want to write an
> user space application to open the device and get the handle. What will the
> parameter(Path) to the "open" function in the user application. How will I
> find to
> which hub port my device is connected ?
>
> Any input will be highly useful!!
Taking the printer driver as an example.
You have a data structure here called usblp for your interface
In probe:
usb_set_intfdata (intf, usblp);
^^^ associate the interface to your data structure
usblp->present = 1;
retval = usb_register_dev(intf, &usblp_class);
^^^ export your interface to user space
if (retval) {
err("Not able to get a minor for this device.");
goto abort_intfdata;
}
usblp->minor = intf->minor;
^^^ associate the export with your data structure
in open:
int minor = iminor(inode);
struct usblp *usblp;
struct usb_interface *intf;
int retval;
if (minor < 0)
return -ENODEV;
down (&usblp_sem);
retval = -ENODEV;
intf = usb_find_interface(&usblp_driver, minor);
^^^ walk association user space -> interface
if (!intf) {
goto out;
}
usblp = usb_get_intfdata (intf);
^^^ walk interface -> data structure
file->private_data = usblp;
^^^ set association between task in user space and data structure
in read/write/... :
struct usblp *usblp = file->private_data;
^^^ follow association
There are other ways, too. Use the source.
HTH
Oliver
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