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USB: add usbfs ioctl to retrieve the connection speed

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The usbfs interface does not provide any way for the user to learn the
speed at which a device is connected.  The current API includes a
USBDEVFS_CONNECTINFO ioctl, but all it provides is the device's
address and a one-bit value indicating whether the connection is low
speed.  That may have sufficed in the era of USB-1.1, but it isn't
good enough today.

This patch introduces a new ioctl, USBDEVFS_GET_SPEED, which returns a
numeric value indicating the speed of the connection: unknown, low,
full, high, wireless, super, or super-plus.

Similar information (not exactly the same) is available through sysfs,
but it seems reasonable to provide the actual value in usbfs.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Reinhard Huck <reinhard.huck@thesycon.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alan Stern
2017-06-05 10:28:01 -04:00
committed by Greg Kroah-Hartman
parent 81606aea23
commit c01b244ad8
2 changed files with 9 additions and 0 deletions
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3
drivers/usb/core/devio.c
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@@ -2537,6 +2537,9 @@ static long usbdev_do_ioctl(struct file *file, unsigned int cmd,
case USBDEVFS_DROP_PRIVILEGES:
ret = proc_drop_privileges(ps, p);
break;
case USBDEVFS_GET_SPEED:
ret = ps->dev->speed;
break;
}
done: