linux.py: Allow specifying a separate TTY device

This allows e.g. opening a TTY on the UART serial device after
booting the kernel via USB.

Signed-off-by: Hector Martin <marcan@marcan.st>

proxyclient/linux.py

@@ -8,6 +8,7 @@ parser.add_argument('dtb', type=pathlib.Path)
 parser.add_argument('initramfs', nargs='?', type=pathlib.Path)
 parser.add_argument('--compression', choices=['auto', 'none', 'gz', 'xz'], default='auto')
 parser.add_argument('-b', '--bootargs', type=str, metavar='"boot arguments"')
+parser.add_argument('-t', '--tty', type=str)
 args = parser.parse_args()
 
 from setup import *
@@ -98,5 +99,11 @@ daif = 0xc0
 u.msr(DAIF, daif)
 print("DAIF: %x" % daif)
 
+tty_dev = None
+if args.tty is not None:
+    tty_dev = serial.Serial(args.tty)
+    tty_dev.reset_input_buffer()
+
 p.kboot_boot(kernel_base)
-iface.ttymode()
+
+iface.ttymode(tty_dev)

proxyclient/proxy.py

@@ -134,12 +134,15 @@ class UartInterface:
             sys.stdout.write(chr(c))
             sys.stdout.flush()
 
-    def ttymode(self):
-        tout = self.dev.timeout
-        self.tty_enable = True
-        self.dev.timeout = None
+    def ttymode(self, dev=None):
+        if dev is None:
+            dev = self.dev
 
-        term = Miniterm(self.dev, eol='cr')
+        tout = dev.timeout
+        self.tty_enable = True
+        dev.timeout = None
+
+        term = Miniterm(dev, eol='cr')
         term.exit_character = chr(0x1d)  # GS/CTRL+]
         term.menu_character = chr(0x14)  # Menu: CTRL+T
         term.raw = True
@@ -157,7 +160,7 @@ class UartInterface:
         term.join()
         term.close()
 
-        self.dev.timeout = tout
+        dev.timeout = tout
         self.tty_enable = False
 
     def reply(self, cmd):