tty: Remove more special casing and out of place code

Carry on pushing code out of tty_io when it belongs to other drivers. I'm
not 100% happy with some of this and it will be worth revisiting some of the
exports later when the restructuring work is done.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/char/pty.c

@@ -23,6 +23,7 @@
 #include <linux/mm.h>
 #include <linux/init.h>
 #include <linux/sysctl.h>
+#include <linux/device.h>
 
 #include <asm/uaccess.h>
 #include <asm/system.h>
@@ -332,6 +333,8 @@ int pty_limit = NR_UNIX98_PTY_DEFAULT;
 static int pty_limit_min = 0;
 static int pty_limit_max = NR_UNIX98_PTY_MAX;
 
+static struct cdev ptmx_cdev;
+
 static struct ctl_table pty_table[] = {
 	{
 		.ctl_name	= PTY_MAX,
@@ -408,6 +411,70 @@ static const struct tty_operations ptm_unix98_ops = {
 	.shutdown = pty_shutdown
 };
 
+
+/**
+ *	ptmx_open		-	open a unix 98 pty master
+ *	@inode: inode of device file
+ *	@filp: file pointer to tty
+ *
+ *	Allocate a unix98 pty master device from the ptmx driver.
+ *
+ *	Locking: tty_mutex protects the init_dev work. tty->count should
+ * 		protect the rest.
+ *		allocated_ptys_lock handles the list of free pty numbers
+ */
+
+static int __ptmx_open(struct inode *inode, struct file *filp)
+{
+	struct tty_struct *tty;
+	int retval;
+	int index;
+
+	nonseekable_open(inode, filp);
+
+	/* find a device that is not in use. */
+	index = devpts_new_index();
+	if (index < 0)
+		return index;
+
+	mutex_lock(&tty_mutex);
+	retval = tty_init_dev(ptm_driver, index, &tty, 1);
+	mutex_unlock(&tty_mutex);
+
+	if (retval)
+		goto out;
+
+	set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
+	filp->private_data = tty;
+	file_move(filp, &tty->tty_files);
+
+	retval = devpts_pty_new(tty->link);
+	if (retval)
+		goto out1;
+
+	retval = ptm_driver->ops->open(tty, filp);
+	if (!retval)
+		return 0;
+out1:
+	tty_release_dev(filp);
+	return retval;
+out:
+	devpts_kill_index(index);
+	return retval;
+}
+
+static int ptmx_open(struct inode *inode, struct file *filp)
+{
+	int ret;
+
+	lock_kernel();
+	ret = __ptmx_open(inode, filp);
+	unlock_kernel();
+	return ret;
+}
+
+static struct file_operations ptmx_fops;
+
 static void __init unix98_pty_init(void)
 {
 	ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
@@ -459,7 +526,18 @@ static void __init unix98_pty_init(void)
 
 	pty_table[1].data = &ptm_driver->refcount;
 	register_sysctl_table(pty_root_table);
+
+	/* Now create the /dev/ptmx special device */
+	tty_default_fops(&ptmx_fops);
+	ptmx_fops.open = ptmx_open;
+
+	cdev_init(&ptmx_cdev, &ptmx_fops);
+	if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
+	    register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
+		panic("Couldn't register /dev/ptmx driver\n");
+	device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
 }
+
 #else
 static inline void unix98_pty_init(void) { }
 #endif

drivers/char/tty_ioctl.c

@@ -40,6 +40,15 @@
 #define TERMIOS_OLD	8
 
 
+/**
+ *	tty_chars_in_buffer	-	characters pending
+ *	@tty: terminal
+ *
+ *	Return the number of bytes of data in the device private
+ *	output queue. If no private method is supplied there is assumed
+ *	to be no queue on the device.
+ */
+
 int tty_chars_in_buffer(struct tty_struct *tty)
 {
 	if (tty->ops->chars_in_buffer)
@@ -47,26 +56,49 @@ int tty_chars_in_buffer(struct tty_struct *tty)
 	else
 		return 0;
 }
-
 EXPORT_SYMBOL(tty_chars_in_buffer);
 
+/**
+ *	tty_write_room		-	write queue space
+ *	@tty: terminal
+ *
+ *	Return the number of bytes that can be queued to this device
+ *	at the present time. The result should be treated as a guarantee
+ *	and the driver cannot offer a value it later shrinks by more than
+ *	the number of bytes written. If no method is provided 2K is always
+ *	returned and data may be lost as there will be no flow control.
+ */
+ 
 int tty_write_room(struct tty_struct *tty)
 {
 	if (tty->ops->write_room)
 		return tty->ops->write_room(tty);
 	return 2048;
 }
-
 EXPORT_SYMBOL(tty_write_room);
 
+/**
+ *	tty_driver_flush_buffer	-	discard internal buffer
+ *	@tty: terminal
+ *
+ *	Discard the internal output buffer for this device. If no method
+ *	is provided then either the buffer cannot be hardware flushed or
+ *	there is no buffer driver side.
+ */
 void tty_driver_flush_buffer(struct tty_struct *tty)
 {
 	if (tty->ops->flush_buffer)
 		tty->ops->flush_buffer(tty);
 }
-
 EXPORT_SYMBOL(tty_driver_flush_buffer);
 
+/**
+ *	tty_throttle		-	flow control
+ *	@tty: terminal
+ *
+ *	Indicate that a tty should stop transmitting data down the stack.
+ */
+
 void tty_throttle(struct tty_struct *tty)
 {
 	/* check TTY_THROTTLED first so it indicates our state */
@@ -76,6 +108,13 @@ void tty_throttle(struct tty_struct *tty)
 }
 EXPORT_SYMBOL(tty_throttle);
 
+/**
+ *	tty_unthrottle		-	flow control
+ *	@tty: terminal
+ *
+ *	Indicate that a tty may continue transmitting data down the stack.
+ */
+
 void tty_unthrottle(struct tty_struct *tty)
 {
 	if (test_and_clear_bit(TTY_THROTTLED, &tty->flags) &&
@@ -112,6 +151,11 @@ void tty_wait_until_sent(struct tty_struct *tty, long timeout)
 }
 EXPORT_SYMBOL(tty_wait_until_sent);
 
+
+/*
+ *		Termios Helper Methods
+ */
+
 static void unset_locked_termios(struct ktermios *termios,
 				 struct ktermios *old,
 				 struct ktermios *locked)
@@ -346,6 +390,16 @@ void tty_termios_encode_baud_rate(struct ktermios *termios,
 }
 EXPORT_SYMBOL_GPL(tty_termios_encode_baud_rate);
 
+/**
+ *	tty_encode_baud_rate		-	set baud rate of the tty
+ *	@ibaud: input baud rate
+ *	@obad: output baud rate
+ *
+ *	Update the current termios data for the tty with the new speed
+ *	settings. The caller must hold the termios_mutex for the tty in
+ *	question.
+ */
+
 void tty_encode_baud_rate(struct tty_struct *tty, speed_t ibaud, speed_t obaud)
 {
 	tty_termios_encode_baud_rate(tty->termios, ibaud, obaud);
@@ -430,7 +484,7 @@ EXPORT_SYMBOL(tty_termios_hw_change);
  *	is a bit of layering violation here with n_tty in terms of the
  *	internal knowledge of this function.
  *
- *	Locking: termios_sem
+ *	Locking: termios_mutex
  */
 
 static void change_termios(struct tty_struct *tty, struct ktermios *new_termios)
@@ -508,7 +562,7 @@ static void change_termios(struct tty_struct *tty, struct ktermios *new_termios)
  *	functions before using change_termios to do the actual changes.
  *
  *	Locking:
- *		Called functions take ldisc and termios_sem locks
+ *		Called functions take ldisc and termios_mutex locks
  */
 
 static int set_termios(struct tty_struct *tty, void __user *arg, int opt)
@@ -715,7 +769,7 @@ static void set_sgflags(struct ktermios *termios, int flags)
  *	Updates a terminal from the legacy BSD style terminal information
  *	structure.
  *
- *	Locking: termios_sem
+ *	Locking: termios_mutex
  */
 
 static int set_sgttyb(struct tty_struct *tty, struct sgttyb __user *sgttyb)

drivers/char/vt.c

@@ -100,10 +100,10 @@
 #include <linux/font.h>
 #include <linux/bitops.h>
 #include <linux/notifier.h>
-
-#include <asm/io.h>
+#include <linux/device.h>
+#include <linux/io.h>
 #include <asm/system.h>
-#include <asm/uaccess.h>
+#include <linux/uaccess.h>
 
 #define MAX_NR_CON_DRIVER 16
 
@@ -2352,8 +2352,6 @@ static int do_con_write(struct tty_struct *tty, const unsigned char *buf, int co
 	FLUSH
 	console_conditional_schedule();
 	release_console_sem();
-
-out:
 	notify_update(vc);
 	return n;
 #undef FLUSH
@@ -2784,13 +2782,6 @@ static int con_open(struct tty_struct *tty, struct file *filp)
 	return ret;
 }
 
-/*
- * We take tty_mutex in here to prevent another thread from coming in via init_dev
- * and taking a ref against the tty while we're in the process of forgetting
- * about it and cleaning things up.
- *
- * This is because vcs_remove_sysfs() can sleep and will drop the BKL.
- */
 static void con_close(struct tty_struct *tty, struct file *filp)
 {
 	/* Nothing to do - we defer to shutdown */
@@ -2932,8 +2923,16 @@ static const struct tty_operations con_ops = {
 	.shutdown = con_shutdown
 };
 
-int __init vty_init(void)
+static struct cdev vc0_cdev;
+
+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");
+
 	vcs_init();
 
 	console_driver = alloc_tty_driver(MAX_NR_CONSOLES);
@@ -2952,7 +2951,6 @@ int __init vty_init(void)
 	tty_set_operations(console_driver, &con_ops);
 	if (tty_register_driver(console_driver))
 		panic("Couldn't register console driver\n");
-
 	kbd_init();
 	console_map_init();
 #ifdef CONFIG_PROM_CONSOLE
@@ -3446,7 +3444,7 @@ int register_con_driver(const struct consw *csw, int first, int last)
 	if (retval)
 		goto err;
 
-	con_driver->dev = device_create_drvdata(vtconsole_class, NULL,
+	con_driver->dev = device_create(vtconsole_class, NULL,
 						MKDEV(0, con_driver->node),
 						NULL, "vtcon%i",
 						con_driver->node);
@@ -3557,7 +3555,7 @@ static int __init vtconsole_class_init(void)
 		struct con_driver *con = &registered_con_driver[i];
 
 		if (con->con && !con->dev) {
-			con->dev = device_create_drvdata(vtconsole_class, NULL,
+			con->dev = device_create(vtconsole_class, NULL,
 							 MKDEV(0, con->node),
 							 NULL, "vtcon%i",
 							 con->node);

include/linux/tty.h

@@ -314,6 +314,8 @@ extern int kmsg_redirect;
 extern void console_init(void);
 extern int vcs_init(void);
 
+extern struct class *tty_class;
+
 /**
  *	tty_kref_get		-	get a tty reference
  *	@tty: tty device
@@ -398,6 +400,10 @@ extern int tty_perform_flush(struct tty_struct *tty, unsigned long arg);
 extern dev_t tty_devnum(struct tty_struct *tty);
 extern void proc_clear_tty(struct task_struct *p);
 extern struct tty_struct *get_current_tty(void);
+extern void tty_default_fops(struct file_operations *fops);
+extern int tty_init_dev(struct tty_driver *driver, int idx,
+			struct tty_struct **ret_tty, int first_ok);
+extern void tty_release_dev(struct file *filp);
 
 extern struct mutex tty_mutex;
 

include/linux/vt_kern.h

@@ -96,7 +96,7 @@ void change_console(struct vc_data *new_vc);
 void reset_vc(struct vc_data *vc);
 extern int unbind_con_driver(const struct consw *csw, int first, int last,
 			     int deflt);
-int vty_init(void);
+int vty_init(const struct file_operations *console_fops);
 
 /*
  * vc_screen.c shares this temporary buffer with the console write code so that