usb: usbtmc: Add ioctl USBTMC_IOCTL_API_VERSION

Add ioctl USBTMC_IOCTL_API_VERSION to get current API version
of usbtmc driver.

This is to allow an instrument library to determine whether
the driver API is compatible with the implementation.

The API may change in future versions. Therefore the macro
USBTMC_API_VERSION should be incremented when changing tmc.h
with new flags, ioctls or when changing a significant behavior
of the driver.

Signed-off-by: Guido Kiener <guido.kiener@rohde-schwarz.com>
Reviewed-by: Steve Bayless <steve_bayless@keysight.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
index 964c8e87dacb7a513e753569eb984349b3373946..72867a97ec00003b7fdd108cd6b88f22dfcdc039 100644 (file)
--- a/drivers/usb/class/usbtmc.c
+++ b/drivers/usb/class/usbtmc.c
@@ -22,6 +22,10 @@
 #include <linux/compat.h>
 #include <linux/usb/tmc.h>
 
+/* Increment API VERSION when changing tmc.h with new flags or ioctls
+ * or when changing a significant behavior of the driver.
+ */
+#define USBTMC_API_VERSION (2)
 
 #define USBTMC_HEADER_SIZE     12
 #define USBTMC_MINOR_BASE      176
@@ -2179,6 +2183,11 @@ static long usbtmc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
                                                   (void __user *)arg);
                break;
 
+       case USBTMC_IOCTL_API_VERSION:
+               retval = put_user(USBTMC_API_VERSION,
+                                 (__u32 __user *)arg);
+               break;
+
        case USBTMC488_IOCTL_GET_CAPS:
                retval = copy_to_user((void __user *)arg,
                                &data->usb488_caps,

diff --git a/include/uapi/linux/usb/tmc.h b/include/uapi/linux/usb/tmc.h
index 4b36108b9ccaf13d4d039a6268b82597fc8ad051..fdd4d88a7b95da68e30e309718544ffcf25293c0 100644 (file)
--- a/include/uapi/linux/usb/tmc.h
+++ b/include/uapi/linux/usb/tmc.h
@@ -89,6 +89,7 @@ struct usbtmc_message {
 #define USBTMC_IOCTL_WRITE             _IOWR(USBTMC_IOC_NR, 13, struct usbtmc_message)
 #define USBTMC_IOCTL_READ              _IOWR(USBTMC_IOC_NR, 14, struct usbtmc_message)
 #define USBTMC_IOCTL_WRITE_RESULT      _IOWR(USBTMC_IOC_NR, 15, __u32)
+#define USBTMC_IOCTL_API_VERSION       _IOR(USBTMC_IOC_NR, 16, __u32)
 
 #define USBTMC488_IOCTL_GET_CAPS       _IOR(USBTMC_IOC_NR, 17, unsigned char)
 #define USBTMC488_IOCTL_READ_STB       _IOR(USBTMC_IOC_NR, 18, unsigned char)