v4.19.13 snapshot.
diff --git a/arch/um/drivers/stdio_console.c b/arch/um/drivers/stdio_console.c
new file mode 100644
index 0000000..c90817b
--- /dev/null
+++ b/arch/um/drivers/stdio_console.c
@@ -0,0 +1,202 @@
+/*
+ * Copyright (C) 2000, 2001 Jeff Dike (jdike@karaya.com)
+ * Licensed under the GPL
+ */
+
+#include <linux/posix_types.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/types.h>
+#include <linux/major.h>
+#include <linux/kdev_t.h>
+#include <linux/console.h>
+#include <linux/string.h>
+#include <linux/sched.h>
+#include <linux/list.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/slab.h>
+#include <linux/hardirq.h>
+#include <asm/current.h>
+#include <asm/irq.h>
+#include "stdio_console.h"
+#include "chan.h"
+#include <irq_user.h>
+#include "mconsole_kern.h"
+#include <init.h>
+
+#define MAX_TTYS (16)
+
+static void stdio_announce(char *dev_name, int dev)
+{
+ printk(KERN_INFO "Virtual console %d assigned device '%s'\n", dev,
+ dev_name);
+}
+
+/* Almost const, except that xterm_title may be changed in an initcall */
+static struct chan_opts opts = {
+ .announce = stdio_announce,
+ .xterm_title = "Virtual Console #%d",
+ .raw = 1,
+};
+
+static int con_config(char *str, char **error_out);
+static int con_get_config(char *dev, char *str, int size, char **error_out);
+static int con_remove(int n, char **con_remove);
+
+
+/* Const, except for .mc.list */
+static struct line_driver driver = {
+ .name = "UML console",
+ .device_name = "tty",
+ .major = TTY_MAJOR,
+ .minor_start = 0,
+ .type = TTY_DRIVER_TYPE_CONSOLE,
+ .subtype = SYSTEM_TYPE_CONSOLE,
+ .read_irq = CONSOLE_IRQ,
+ .read_irq_name = "console",
+ .write_irq = CONSOLE_WRITE_IRQ,
+ .write_irq_name = "console-write",
+ .mc = {
+ .list = LIST_HEAD_INIT(driver.mc.list),
+ .name = "con",
+ .config = con_config,
+ .get_config = con_get_config,
+ .id = line_id,
+ .remove = con_remove,
+ },
+};
+
+/* The array is initialized by line_init, at initcall time. The
+ * elements are locked individually as needed.
+ */
+static char *vt_conf[MAX_TTYS];
+static char *def_conf;
+static struct line vts[MAX_TTYS];
+
+static int con_config(char *str, char **error_out)
+{
+ return line_config(vts, ARRAY_SIZE(vts), str, &opts, error_out);
+}
+
+static int con_get_config(char *dev, char *str, int size, char **error_out)
+{
+ return line_get_config(dev, vts, ARRAY_SIZE(vts), str, size, error_out);
+}
+
+static int con_remove(int n, char **error_out)
+{
+ return line_remove(vts, ARRAY_SIZE(vts), n, error_out);
+}
+
+/* Set in an initcall, checked in an exitcall */
+static int con_init_done = 0;
+
+static int con_install(struct tty_driver *driver, struct tty_struct *tty)
+{
+ return line_install(driver, tty, &vts[tty->index]);
+}
+
+static const struct tty_operations console_ops = {
+ .open = line_open,
+ .install = con_install,
+ .close = line_close,
+ .write = line_write,
+ .put_char = line_put_char,
+ .write_room = line_write_room,
+ .chars_in_buffer = line_chars_in_buffer,
+ .flush_buffer = line_flush_buffer,
+ .flush_chars = line_flush_chars,
+ .set_termios = line_set_termios,
+ .throttle = line_throttle,
+ .unthrottle = line_unthrottle,
+ .hangup = line_hangup,
+};
+
+static void uml_console_write(struct console *console, const char *string,
+ unsigned len)
+{
+ struct line *line = &vts[console->index];
+ unsigned long flags;
+
+ spin_lock_irqsave(&line->lock, flags);
+ console_write_chan(line->chan_out, string, len);
+ spin_unlock_irqrestore(&line->lock, flags);
+}
+
+static struct tty_driver *uml_console_device(struct console *c, int *index)
+{
+ *index = c->index;
+ return driver.driver;
+}
+
+static int uml_console_setup(struct console *co, char *options)
+{
+ struct line *line = &vts[co->index];
+
+ return console_open_chan(line, co);
+}
+
+/* No locking for register_console call - relies on single-threaded initcalls */
+static struct console stdiocons = {
+ .name = "tty",
+ .write = uml_console_write,
+ .device = uml_console_device,
+ .setup = uml_console_setup,
+ .flags = CON_PRINTBUFFER|CON_ANYTIME,
+ .index = -1,
+};
+
+static int stdio_init(void)
+{
+ char *new_title;
+ int err;
+ int i;
+
+ err = register_lines(&driver, &console_ops, vts,
+ ARRAY_SIZE(vts));
+ if (err)
+ return err;
+
+ printk(KERN_INFO "Initialized stdio console driver\n");
+
+ new_title = add_xterm_umid(opts.xterm_title);
+ if(new_title != NULL)
+ opts.xterm_title = new_title;
+
+ for (i = 0; i < MAX_TTYS; i++) {
+ char *error;
+ char *s = vt_conf[i];
+ if (!s)
+ s = def_conf;
+ if (!s)
+ s = i ? CONFIG_CON_CHAN : CONFIG_CON_ZERO_CHAN;
+ if (setup_one_line(vts, i, s, &opts, &error))
+ printk(KERN_ERR "setup_one_line failed for "
+ "device %d : %s\n", i, error);
+ }
+
+ con_init_done = 1;
+ register_console(&stdiocons);
+ return 0;
+}
+late_initcall(stdio_init);
+
+static void console_exit(void)
+{
+ if (!con_init_done)
+ return;
+ close_lines(vts, ARRAY_SIZE(vts));
+}
+__uml_exitcall(console_exit);
+
+static int console_chan_setup(char *str)
+{
+ if (!strncmp(str, "sole=", 5)) /* console= option specifies tty */
+ return 0;
+
+ line_setup(vt_conf, MAX_TTYS, &def_conf, str, "console");
+ return 1;
+}
+__setup("con", console_chan_setup);
+__channel_help(console_chan_setup, "con");