[PATCH 3/7 v6] initdev:kernel:Await console discovery

[David VomLehn <dvomlehn@xxxxxxxxx>]

Wait for the console device to become available or for it to be determined
that no console is attached a boot time.

Signed-off-by: David VomLehn <dvomlehn@xxxxxxxxx>
---
 drivers/accessibility/braille/braille_console.c |    2 +
 kernel/printk.c                                 |   29 ++++++++++++++++++++++-
 2 files changed, 30 insertions(+), 1 deletions(-)

diff --git a/drivers/accessibility/braille/braille_console.c b/drivers/accessibility/braille/braille_console.c
index d672cfe..6d1693f 100644
--- a/drivers/accessibility/braille/braille_console.c
+++ b/drivers/accessibility/braille/braille_console.c
@@ -378,6 +378,8 @@ int braille_register_console(struct console *console, int index,
 	braille_co = console;
 	register_keyboard_notifier(&keyboard_notifier_block);
 	register_vt_notifier(&vt_notifier_block);
+
+	initdev_registered(INITDEV_CONSOLE_TYPE);
 	return 0;
 }
 
diff --git a/kernel/printk.c b/kernel/printk.c
index 5052b54..7cdc91c 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -33,6 +33,7 @@
 #include <linux/bootmem.h>
 #include <linux/syscalls.h>
 #include <linux/kexec.h>
+#include <linux/device.h>
 
 #include <asm/uaccess.h>
 
@@ -1075,8 +1076,10 @@ void console_unblank(void)
 
 /*
  * Return the console tty driver structure and its associated index
+ * @index:	Pointer to the device index
+ * Returns NULL if no driver available, otherwise a pointer to the TTY driver.
  */
-struct tty_driver *console_device(int *index)
+struct tty_driver *_console_device(int *index)
 {
 	struct console *c;
 	struct tty_driver *driver = NULL;
@@ -1094,6 +1097,29 @@ struct tty_driver *console_device(int *index)
 }
 
 /*
+ * Returns true if all specific consoles are registered, false otherwise
+ */
+static bool have_all_consoles(void)
+{
+	struct tty_driver *driver;
+	int		index;
+
+	driver = _console_device(&index);
+
+	return driver != NULL;
+}
+
+struct tty_driver *console_device(int *index)
+{
+	struct tty_driver *driver;
+	initdev_wait(INITDEV_CONSOLE_TYPE, have_all_consoles);
+
+	driver = _console_device(index);
+
+	return driver;
+}
+
+/*
  * Prevent further output on the passed console device so that (for example)
  * serial drivers can disable console output before suspending a port, and can
  * re-enable output afterwards.
@@ -1230,6 +1256,7 @@ void register_console(struct console *console)
 		spin_unlock_irqrestore(&logbuf_lock, flags);
 	}
 	release_console_sem();
+	initdev_registered(INITDEV_CONSOLE_TYPE);
 }
 EXPORT_SYMBOL(register_console);
 
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