usb: usbtmc: Add ioctl USBTMC_IOCTL_CANCEL_IO

ioctl USBTMC_IOCTL_CANCEL_IO stops and kills all flying urbs of
last USBTMC_IOCTL_READ and USBTMC_IOCTL_WRITE function calls.
A subsequent call to USBTMC_IOCTL_READ or
USBTMC_IOCTL_WRITE_RESULT returns -ECANCELED with
information about current transferred data.
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>

drivers/usb/class/usbtmc.c

@@ -2126,6 +2126,10 @@ static long usbtmc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	case USBTMC488_IOCTL_TRIGGER:
 		retval = usbtmc488_ioctl_trigger(file_data);
 		break;
+
+	case USBTMC_IOCTL_CANCEL_IO:
+		retval = usbtmc_ioctl_cancel_io(file_data);
+		break;
 	}
 
 skip_io_on_zombie:

include/uapi/linux/usb/tmc.h

@@ -97,6 +97,9 @@ struct usbtmc_message {
 #define USBTMC488_IOCTL_LOCAL_LOCKOUT	_IO(USBTMC_IOC_NR, 21)
 #define USBTMC488_IOCTL_TRIGGER		_IO(USBTMC_IOC_NR, 22)
 
+/* Cancel and cleanup asynchronous calls */
+#define USBTMC_IOCTL_CANCEL_IO		_IO(USBTMC_IOC_NR, 35)
+
 /* Driver encoded usb488 capabilities */
 #define USBTMC488_CAPABILITY_TRIGGER         1
 #define USBTMC488_CAPABILITY_SIMPLE          2