tty: add 'active' sysfs attribute to tty0 and console device
tty: add 'active' sysfs attribute to tty0 and console device
Userspace can query the actual virtual console, and the configured
console devices behind /dev/tt0 and /dev/console.
The last entry in the list of devices is the active device, analog
to the console= kernel command line option.
The attribute supports poll(), which is raised when the virtual
console is changed or /dev/console is reconfigured.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
index 0000000..b138b66
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index c05c5af..be5ab4a 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -3232,9 +3232,45 @@
postcore_initcall(tty_class_init);
/* 3/2004 jmc: why do these devices exist? */
-
static struct cdev tty_cdev, console_cdev;
+static ssize_t show_cons_active(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct console *cs[16];
+ int i = 0;
+ struct console *c;
+ ssize_t count = 0;
+
+ acquire_console_sem();
+ for (c = console_drivers; c; c = c->next) {
+ if (!c->device)
+ continue;
+ if (!c->write)
+ continue;
+ if ((c->flags & CON_ENABLED) == 0)
+ continue;
+ cs[i++] = c;
+ if (i >= ARRAY_SIZE(cs))
+ break;
+ }
+ while (i--)
+ count += sprintf(buf + count, "%s%d%c",
+ cs[i]->name, cs[i]->index, i ? ' ':'\n');
+ release_console_sem();
+
+ return count;
+}
+static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
+
+static struct device *consdev;
+
+void console_sysfs_notify(void)
+{
+ if (consdev)
+ sysfs_notify(&consdev->kobj, NULL, "active");
+}
+
/*
* Ok, now we can initialize the rest of the tty devices and can count
* on memory allocations, interrupts etc..
@@ -3245,15 +3281,18 @@
if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
panic("Couldn't register /dev/tty driver\n");
- device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL,
- "tty");
+ device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
cdev_init(&console_cdev, &console_fops);
if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
panic("Couldn't register /dev/console driver\n");
- device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), NULL,
+ consdev = device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), NULL,
"console");
+ if (IS_ERR(consdev))
+ consdev = NULL;
+ else
+ device_create_file(consdev, &dev_attr_active);
#ifdef CONFIG_VT
vty_init(&console_fops);