char: ttyprintk: register console

Register a console in the ttyprintk driver so that it can be selected
for /dev/console with console=ttyprintk on the kernel command line,
similar to other console drivers.

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Link: https://lore.kernel.org/r/20220215141750.92808-1-vincent.whitchurch@axis.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index 55f4837..69fd31f 100644 (file)
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -18,7 +18,8 @@ config TTY_PRINTK
          The feature is useful to inline user messages with kernel
          messages.
          In order to use this feature, you should output user messages
-         to /dev/ttyprintk or redirect console to this TTY.
+         to /dev/ttyprintk or redirect console to this TTY, or boot
+         the kernel with console=ttyprintk.
 
          If unsure, say N.
 

diff --git a/drivers/char/ttyprintk.c b/drivers/char/ttyprintk.c
index adf941c..ed45d04 100644 (file)
--- a/drivers/char/ttyprintk.c
+++ b/drivers/char/ttyprintk.c
@@ -11,6 +11,7 @@
  * of the boot process, for example.
  */
 
+#include <linux/console.h>
 #include <linux/device.h>
 #include <linux/serial.h>
 #include <linux/tty.h>
@@ -163,6 +164,18 @@ static const struct tty_port_operations tpk_port_ops = {
 
 static struct tty_driver *ttyprintk_driver;
 
+static struct tty_driver *ttyprintk_console_device(struct console *c,
+                                                  int *index)
+{
+       *index = 0;
+       return ttyprintk_driver;
+}
+
+static struct console ttyprintk_console = {
+       .name = "ttyprintk",
+       .device = ttyprintk_console_device,
+};
+
 static int __init ttyprintk_init(void)
 {
        int ret;
@@ -195,6 +208,8 @@ static int __init ttyprintk_init(void)
                goto error;
        }
 
+       register_console(&ttyprintk_console);
+
        return 0;
 
 error:
@@ -205,6 +220,7 @@ error:
 
 static void __exit ttyprintk_exit(void)
 {
+       unregister_console(&ttyprintk_console);
        tty_unregister_driver(ttyprintk_driver);
        tty_driver_kref_put(ttyprintk_driver);
        tty_port_destroy(&tpk_port.port);