Implemented auto port detection

src/args.rs

@@ -6,8 +6,8 @@ use argp::FromArgs;
 #[argp(description = "tulflash - Flashing utility for the TUL Výukový Přípravek v1.1™")]
 pub struct Args {
 	#[argp(option)]
-	#[argp(description = "Path to the serial port. Probably will be `/dev/ttyUSBx` on Linux, `/dev/tty.usbserial-xxx` on macOS or `COMx` on Windows.")]
-	pub port: OsString,
+	#[argp(description = "Path to the serial port if auto detection fails. Probably will be `/dev/ttyUSBx` on Linux, `/dev/tty.usbserial-xxx` on macOS or `COMx` on Windows.")]
+	pub port: Option<OsString>,
 
 	#[argp(switch)]
 	#[argp(description = "Try this if it does not work the first time.")]

src/main.rs

@@ -216,7 +216,17 @@ fn main() {
 
 	let start = SystemTime::now();
 
-	let mut target = PhysicalTarget::init(args.port, if args.slow { 57600 } else { 312500 }).unwrap();
+	let port = args.port.or_else(|| {
+		for port in serial_enumerator::get_serial_list() {
+			if let Some(vendor) = port.vendor && vendor.as_str() == "TUL" {
+				return Some(port.name.into())
+			}
+		}
+
+		None
+	}).unwrap();
+
+	let mut target = PhysicalTarget::init(port, if args.slow { 57600 } else { 312500 }).unwrap();
 
 	let res = match args.command {
 		ArgCommand::Read(args) => read_chip(args, &mut target),