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@xxxxxxxxxxxxxxxxxxx>
Reported-by: Reinhard Huck <reinhard.huck@xxxxxxxxxxx>
---
v2: Use the USB_SPEED_* values already defined in
include/uapi/linux/usb/ch9.h instead of inventing new constants.
[as1832b]
drivers/usb/core/devio.c | 3 +++
include/uapi/linux/usbdevice_fs.h | 6 ++++++
2 files changed, 9 insertions(+)
Index: usb-4.x/drivers/usb/core/devio.c
===================================================================
--- usb-4.x.orig/drivers/usb/core/devio.c
+++ usb-4.x/drivers/usb/core/devio.c
@@ -2537,6 +2537,9 @@ static long usbdev_do_ioctl(struct file
case USBDEVFS_DROP_PRIVILEGES:
ret = proc_drop_privileges(ps, p);
break;
+ case USBDEVFS_GET_SPEED:
+ ret = ps->dev->speed;
+ break;
}
done:
Index: usb-4.x/include/uapi/linux/usbdevice_fs.h
===================================================================
--- usb-4.x.orig/include/uapi/linux/usbdevice_fs.h
+++ usb-4.x/include/uapi/linux/usbdevice_fs.h
@@ -156,6 +156,11 @@ struct usbdevfs_streams {
unsigned char eps[0];
};
+/*
+ * USB_SPEED_* values returned by USBDEVFS_GET_SPEED are defined in
+ * linux/usb/ch9.h
+ */
+
#define USBDEVFS_CONTROL _IOWR('U', 0, struct usbdevfs_ctrltransfer)
#define USBDEVFS_CONTROL32 _IOWR('U', 0, struct usbdevfs_ctrltransfer32)
#define USBDEVFS_BULK _IOWR('U', 2, struct usbdevfs_bulktransfer)
@@ -190,5 +195,6 @@ struct usbdevfs_streams {
#define USBDEVFS_ALLOC_STREAMS _IOR('U', 28, struct usbdevfs_streams)
#define USBDEVFS_FREE_STREAMS _IOR('U', 29, struct usbdevfs_streams)
#define USBDEVFS_DROP_PRIVILEGES _IOW('U', 30, __u32)
+#define USBDEVFS_GET_SPEED _IO('U', 31)
#endif /* _UAPI_LINUX_USBDEVICE_FS_H */
--
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