From fbc92a3455577ab17615cbcb91826399061bd789 Mon Sep 17 00:00:00 2001 From: Kay Sievers Date: Wed, 1 Dec 2010 18:51:05 +0100 Subject: 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 Signed-off-by: Greg Kroah-Hartman index 0000000..b138b66 --- drivers/tty/tty_io.c | 47 +++++++++++++++++++++++++++++++++++++++++++---- drivers/tty/vt/vt.c | 23 ++++++++++++++++++++++- 2 files changed, 65 insertions(+), 5 deletions(-) (limited to 'drivers/tty') diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index c05c5af5aa04..be5ab4ac0b93 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -3232,9 +3232,45 @@ static int __init tty_class_init(void) 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 @@ int __init tty_init(void) 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); diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c index a8ec48ed14d9..76407eca9ab0 100644 --- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -235,6 +235,14 @@ enum { blank_vesa_wait, }; +/* + * /sys/class/tty/tty0/ + * + * the attribute 'active' contains the name of the current vc + * console and it supports poll() to detect vc switches + */ +static struct device *tty0dev; + /* * Notifier list for console events. */ @@ -688,6 +696,8 @@ void redraw_screen(struct vc_data *vc, int is_switch) save_screen(old_vc); set_origin(old_vc); } + if (tty0dev) + sysfs_notify(&tty0dev->kobj, NULL, "active"); } else { hide_cursor(vc); redraw = 1; @@ -2967,13 +2977,24 @@ static const struct tty_operations con_ops = { static struct cdev vc0_cdev; +static ssize_t show_tty_active(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return sprintf(buf, "tty%d\n", fg_console + 1); +} +static DEVICE_ATTR(active, S_IRUGO, show_tty_active, NULL); + int __init vty_init(const struct file_operations *console_fops) { cdev_init(&vc0_cdev, console_fops); if (cdev_add(&vc0_cdev, MKDEV(TTY_MAJOR, 0), 1) || register_chrdev_region(MKDEV(TTY_MAJOR, 0), 1, "/dev/vc/0") < 0) panic("Couldn't register /dev/tty0 driver\n"); - device_create(tty_class, NULL, MKDEV(TTY_MAJOR, 0), NULL, "tty0"); + tty0dev = device_create(tty_class, NULL, MKDEV(TTY_MAJOR, 0), NULL, "tty0"); + if (IS_ERR(tty0dev)) + tty0dev = NULL; + else + device_create_file(tty0dev, &dev_attr_active); vcs_init(); -- cgit v1.2.3-55-g7522