v4.19.13 snapshot.
diff --git a/arch/um/drivers/tty.c b/arch/um/drivers/tty.c
new file mode 100644
index 0000000..eaa201b
--- /dev/null
+++ b/arch/um/drivers/tty.c
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
+ * Licensed under the GPL
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <termios.h>
+#include "chan_user.h"
+#include <os.h>
+#include <um_malloc.h>
+
+struct tty_chan {
+ char *dev;
+ int raw;
+ struct termios tt;
+};
+
+static void *tty_chan_init(char *str, int device, const struct chan_opts *opts)
+{
+ struct tty_chan *data;
+
+ if (*str != ':') {
+ printk(UM_KERN_ERR "tty_init : channel type 'tty' must specify "
+ "a device\n");
+ return NULL;
+ }
+ str++;
+
+ data = uml_kmalloc(sizeof(*data), UM_GFP_KERNEL);
+ if (data == NULL)
+ return NULL;
+ *data = ((struct tty_chan) { .dev = str,
+ .raw = opts->raw });
+
+ return data;
+}
+
+static int tty_open(int input, int output, int primary, void *d,
+ char **dev_out)
+{
+ struct tty_chan *data = d;
+ int fd, err, mode = 0;
+
+ if (input && output)
+ mode = O_RDWR;
+ else if (input)
+ mode = O_RDONLY;
+ else if (output)
+ mode = O_WRONLY;
+
+ fd = open(data->dev, mode);
+ if (fd < 0)
+ return -errno;
+
+ if (data->raw) {
+ CATCH_EINTR(err = tcgetattr(fd, &data->tt));
+ if (err)
+ return err;
+
+ err = raw(fd);
+ if (err)
+ return err;
+ }
+
+ *dev_out = data->dev;
+ return fd;
+}
+
+const struct chan_ops tty_ops = {
+ .type = "tty",
+ .init = tty_chan_init,
+ .open = tty_open,
+ .close = generic_close,
+ .read = generic_read,
+ .write = generic_write,
+ .console_write = generic_console_write,
+ .window_size = generic_window_size,
+ .free = generic_free,
+ .winch = 0,
+};