tty: add 'active' sysfs attribute to tty0 and console device (fbc92a34) · Commits · 戴 / test

Documentation/ABI/testing/sysfs-tty

0 → 100644

+19 −0

Original line number	Diff line number	Diff line
		What: /sys/class/tty/console/active
		Date: Nov 2010
		Contact: Kay Sievers <kay.sievers@vrfy.org>
		Description:
		Shows the list of currently configured
		console devices, like 'tty1 ttyS0'.
		The last entry in the file is the active
		device connected to /dev/console.
		The file supports poll() to detect virtual
		console switches.

		What: /sys/class/tty/tty0/active
		Date: Nov 2010
		Contact: Kay Sievers <kay.sievers@vrfy.org>
		Description:
		Shows the currently active virtual console
		device, like 'tty1'.
		The file supports poll() to detect virtual
		console switches.

drivers/tty/tty_io.c

+43 −4

Original line number	Diff line number	Diff line
		@@ -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);

drivers/tty/vt/vt.c

+22 −1

Original line number	Diff line number	Diff line
		@@ -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();

include/linux/console.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -151,7 +151,7 @@ extern int is_console_locked(void);
		extern int braille_register_console(struct console *, int index,
		char console_options, char braille_options);
		extern int braille_unregister_console(struct console *);

		extern void console_sysfs_notify(void);
		extern int console_suspend_enabled;

		/* Suspend and resume console messages over PM events */

kernel/printk.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -1332,6 +1332,7 @@ void register_console(struct console *newcon)
		spin_unlock_irqrestore(&logbuf_lock, flags);
		}
		release_console_sem();
		console_sysfs_notify();

		/*
		* By unregistering the bootconsoles after we enable the real console
		@@ -1390,6 +1391,7 @@ int unregister_console(struct console *console)
		console_drivers->flags \|= CON_CONSDEV;

		release_console_sem();
		console_sysfs_notify();
		return res;
		}
		EXPORT_SYMBOL(unregister_console);

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