Input: uinput - add UI_GET_VERSION ioctl

This ioctl is the counterpart to EVIOCGVERSION and returns the
uinput-version the kernel was compiled with.

Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

2 files changed, 15 insertions, 0 deletions

diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c
index 883f045f37df..421e29e4cd81 100644
--- a/drivers/input/misc/uinput.c
+++ b/drivers/input/misc/uinput.c
@@ -723,6 +723,12 @@ static long uinput_ioctl_handler(struct file *file, unsigned int cmd,
         }
 
         switch (cmd) {
+                case UI_GET_VERSION:
+                        if (put_user(UINPUT_VERSION,
+                                     (unsigned int __user *)p))
+                                retval = -EFAULT;
+                        goto out;
+
                 case UI_DEV_CREATE:
                         retval = uinput_create_device(udev);
                         goto out;
diff --git a/include/uapi/linux/uinput.h b/include/uapi/linux/uinput.h
index 0389b489bbba..baeab83deb64 100644
--- a/include/uapi/linux/uinput.h
+++ b/include/uapi/linux/uinput.h
@@ -84,6 +84,15 @@ struct uinput_ff_erase {
  */
 #define UI_GET_SYSNAME(len)     _IOC(_IOC_READ, UINPUT_IOCTL_BASE, 300, len)
 
+/**
+ * UI_GET_VERSION - Return version of uinput protocol
+ *
+ * This writes uinput protocol version implemented by the kernel into
+ * the integer pointed to by the ioctl argument. The protocol version
+ * is hard-coded in the kernel and is independent of the uinput device.
+ */
+#define UI_GET_VERSION          _IOR(UINPUT_IOCTL_BASE, 301, unsigned int)
+
 /*
  * To write a force-feedback-capable driver, the upload_effect
  * and erase_effect callbacks in input_dev must be implemented.