From 7cbe5dca399a50ce8aa74314b1d276e2fb904e1b Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Mon, 29 Jun 2009 10:56:54 -0400 Subject: USB: add API for userspace drivers to "claim" ports This patch (as1258) implements a feature that users have been asking for: It gives programs the ability to "claim" a port on a hub, via a new usbfs ioctl. A device plugged into a "claimed" port will not be touched by the kernel beyond the immediate necessities of initialization and enumeration. In particular, when a device is plugged into a "claimed" port, the kernel will not select and install a configuration. And when a config is installed by usbfs or sysfs, the kernel will not probe any drivers for any of the interfaces. (However the kernel will fetch various string descriptors during enumeration. One could argue that this isn't really necessary, but the strings are exported in sysfs.) The patch does not guarantee exclusive access to these devices; it is still possible for more than one program to open the device file concurrently. Programs are responsible for coordinating access among themselves. A demonstration program showing how to use the new interface can be found in an attachment to http://marc.info/?l=linux-usb&m=124345857431452&w=2 The patch also makes a small simplification to the hub driver, replacing a bunch of more-or-less useless variants of "out of memory" with a single message. Signed-off-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/generic.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'drivers/usb/core/generic.c') diff --git a/drivers/usb/core/generic.c b/drivers/usb/core/generic.c index 30ecac3af15a..05e6d313961e 100644 --- a/drivers/usb/core/generic.c +++ b/drivers/usb/core/generic.c @@ -158,7 +158,9 @@ static int generic_probe(struct usb_device *udev) /* Choose and set the configuration. This registers the interfaces * with the driver core and lets interface drivers bind to them. */ - if (udev->authorized == 0) + if (usb_device_is_owned(udev)) + ; /* Don't configure if the device is owned */ + else if (udev->authorized == 0) dev_err(&udev->dev, "Device is not authorized for usage\n"); else { c = usb_choose_configuration(udev); -- cgit v1.2.3