[PATCH] tty_driver refcounting

added helper functions for allocation and freeing tty_driver

drivers/char/tty_io.c

@@ -2213,6 +2213,58 @@ EXPORT_SYMBOL(tty_register_device);
 EXPORT_SYMBOL(tty_unregister_device);
 
 static struct kobject tty_kobj = {.name = "tty"};
+
+struct tty_driver *alloc_tty_driver(int lines)
+{
+	struct tty_driver *driver;
+
+	driver = kmalloc(sizeof(struct tty_driver), GFP_KERNEL);
+	if (driver) {
+		memset(driver, 0, sizeof(struct tty_driver));
+		driver->magic = TTY_DRIVER_MAGIC;
+		driver->num = lines;
+		/* later we'll move allocation of tables here */
+	}
+	return driver;
+}
+
+void put_tty_driver(struct tty_driver *driver)
+{
+	kfree(driver);
+}
+
+void tty_set_operations(struct tty_driver *driver, struct tty_operations *op)
+{
+	driver->open = op->open;
+	driver->close = op->close;
+	driver->write = op->write;
+	driver->put_char = op->put_char;
+	driver->flush_chars = op->flush_chars;
+	driver->write_room = op->write_room;
+	driver->chars_in_buffer = op->chars_in_buffer;
+	driver->ioctl = op->ioctl;
+	driver->set_termios = op->set_termios;
+	driver->throttle = op->throttle;
+	driver->unthrottle = op->unthrottle;
+	driver->stop = op->stop;
+	driver->start = op->start;
+	driver->hangup = op->hangup;
+	driver->break_ctl = op->break_ctl;
+	driver->flush_buffer = op->flush_buffer;
+	driver->set_ldisc = op->set_ldisc;
+	driver->wait_until_sent = op->wait_until_sent;
+	driver->send_xchar = op->send_xchar;
+	driver->read_proc = op->read_proc;
+	driver->write_proc = op->write_proc;
+	driver->tiocmget = op->tiocmget;
+	driver->tiocmset = op->tiocmset;
+}
+
+
+EXPORT_SYMBOL(alloc_tty_driver);
+EXPORT_SYMBOL(put_tty_driver);
+EXPORT_SYMBOL(tty_set_operations);
+
 /*
  * Called by a tty driver to register itself.
  */

include/linux/tty_driver.h

@@ -119,6 +119,39 @@
 #include <linux/list.h>
 #include <linux/cdev.h>
 
+struct tty_struct;
+
+struct tty_operations {
+	int  (*open)(struct tty_struct * tty, struct file * filp);
+	void (*close)(struct tty_struct * tty, struct file * filp);
+	int  (*write)(struct tty_struct * tty, int from_user,
+		      const unsigned char *buf, int count);
+	void (*put_char)(struct tty_struct *tty, unsigned char ch);
+	void (*flush_chars)(struct tty_struct *tty);
+	int  (*write_room)(struct tty_struct *tty);
+	int  (*chars_in_buffer)(struct tty_struct *tty);
+	int  (*ioctl)(struct tty_struct *tty, struct file * file,
+		    unsigned int cmd, unsigned long arg);
+	void (*set_termios)(struct tty_struct *tty, struct termios * old);
+	void (*throttle)(struct tty_struct * tty);
+	void (*unthrottle)(struct tty_struct * tty);
+	void (*stop)(struct tty_struct *tty);
+	void (*start)(struct tty_struct *tty);
+	void (*hangup)(struct tty_struct *tty);
+	void (*break_ctl)(struct tty_struct *tty, int state);
+	void (*flush_buffer)(struct tty_struct *tty);
+	void (*set_ldisc)(struct tty_struct *tty);
+	void (*wait_until_sent)(struct tty_struct *tty, int timeout);
+	void (*send_xchar)(struct tty_struct *tty, char ch);
+	int (*read_proc)(char *page, char **start, off_t off,
+			  int count, int *eof, void *data);
+	int (*write_proc)(struct file *file, const char *buffer,
+			  unsigned long count, void *data);
+	int (*tiocmget)(struct tty_struct *tty, struct file *file);
+	int (*tiocmset)(struct tty_struct *tty, struct file *file,
+			unsigned int set, unsigned int clear);
+};
+
 struct tty_driver {
 	int	magic;		/* magic number for this structure */
 	struct cdev cdev;
@@ -148,7 +181,7 @@ struct tty_driver {
 	
 	/*
 	 * Interface routines from the upper tty layer to the tty
-	 * driver.
+	 * driver.	Will be replaced with struct tty_operations.
 	 */
 	int  (*open)(struct tty_struct * tty, struct file * filp);
 	void (*close)(struct tty_struct * tty, struct file * filp);
@@ -178,11 +211,16 @@ struct tty_driver {
 	int (*tiocmget)(struct tty_struct *tty, struct file *file);
 	int (*tiocmset)(struct tty_struct *tty, struct file *file,
 			unsigned int set, unsigned int clear);
+
 	struct list_head tty_drivers;
 };
 
 extern struct list_head tty_drivers;
 
+struct tty_driver *alloc_tty_driver(int lines);
+void put_tty_driver(struct tty_driver *driver);
+void tty_set_operations(struct tty_driver *driver, struct tty_operations *op);
+
 /* tty driver magic number */
 #define TTY_DRIVER_MAGIC		0x5402