There are a few (new) usbdevfs capabilities which an application cannot
discover in any other way then checking the kernel version. There are 3
problems with this:
1) It is just not very pretty
2) Given the tendency of enterprise distros to backport stuff it is not
reliable
3) Some of these features turn out to not work with certain host controllers,
making depending on them based on the kernel version not a good idea
This patch besides adding the new ioctl also adds flags the following existing
capabilities:
USBDEVFS_CAP_ZERO_PACKET, available since 2.6.31
USBDEVFS_CAP_BULK_CONTINUATION, available since 2.6.32, except for XHCI
USBDEVFS_CAP_NO_PACKET_SIZE_LIM, available since 3.3
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
drivers/usb/core/devio.c | 16 ++++++++++++++++
include/linux/usbdevice_fs.h | 7 +++++++
2 files changed, 23 insertions(+)
diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index 5c15acd..de5631e 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -1818,6 +1818,19 @@ static int proc_release_port(struct dev_state *ps, void __user *arg)
return usb_hub_release_port(ps->dev, portnum, ps);
}
+static int proc_get_capabilities(struct dev_state *ps, void __user *arg)
+{
+ __u32 caps = 0;
+
+ caps |= USBDEVFS_CAP_ZERO_PACKET | USBDEVFS_CAP_NO_PACKET_SIZE_LIM;
+ caps |= USBDEVFS_CAP_BULK_CONTINUATION;
+
+ if (put_user(caps, (__u32 __user *)arg))
+ return -EFAULT;
+
+ return caps;
+}
+
/*
* NOTE: All requests here that have interface numbers as parameters
* are assuming that somehow the configuration has been prevented from
@@ -1988,6 +2001,9 @@ static long usbdev_do_ioctl(struct file *file, unsigned int cmd,
snoop(&dev->dev, "%s: RELEASE_PORT\n", __func__);
ret = proc_release_port(ps, p);
break;
+ case USBDEVFS_GET_CAPABILITIES:
+ ret = proc_get_capabilities(ps, p);
+ break;
}
usb_unlock_device(dev);
if (ret >= 0)
diff --git a/include/linux/usbdevice_fs.h b/include/linux/usbdevice_fs.h
index 15591d2..07b2cea 100644
--- a/include/linux/usbdevice_fs.h
+++ b/include/linux/usbdevice_fs.h
@@ -125,6 +125,11 @@ struct usbdevfs_hub_portinfo {
char port [127]; /* e.g. port 3 connects to device 27 */
};
+/* Device capability flags */
+#define USBDEVFS_CAP_ZERO_PACKET 0x01
+#define USBDEVFS_CAP_BULK_CONTINUATION 0x02
+#define USBDEVFS_CAP_NO_PACKET_SIZE_LIM 0x04
+
#ifdef __KERNEL__
#ifdef CONFIG_COMPAT
#include <linux/compat.h>
@@ -204,4 +209,6 @@ struct usbdevfs_ioctl32 {
#define USBDEVFS_CONNECT _IO('U', 23)
#define USBDEVFS_CLAIM_PORT _IOR('U', 24, unsigned int)
#define USBDEVFS_RELEASE_PORT _IOR('U', 25, unsigned int)
+#define USBDEVFS_GET_CAPABILITIES _IOR('U', 26, __u32)
+
#endif /* _LINUX_USBDEVICE_FS_H */
--
1.7.10.4
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