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Commit 6f67048c authored by Alan Cox's avatar Alan Cox Committed by Linus Torvalds
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tty: Introduce a tty_port common structure 



Every tty driver has its own concept of a port structure and because
they all differ we cannot extract commonality.  Begin fixing this by
creating a structure drivers can elect to use so that over time we can
push fields into this and create commonality and then introduce common
methods.

Signed-off-by: default avatarAlan Cox <alan@redhat.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d87a6d95

drivers/char/tty_io.c

+34 −0
Original line number Diff line number Diff line
@@ -2088,6 +2088,40 @@ ssize_t redirected_tty_write(struct file *file, const char __user *buf, 
	return tty_write(file, buf, count, ppos);

}



void tty_port_init(struct tty_port *port)

{

	memset(port, 0, sizeof(*port));

	init_waitqueue_head(&port->open_wait);

	init_waitqueue_head(&port->close_wait);

	mutex_init(&port->mutex);

}

EXPORT_SYMBOL(tty_port_init);



int tty_port_alloc_xmit_buf(struct tty_port *port)

{

	/* We may sleep in get_zeroed_page() */

	mutex_lock(&port->mutex);

	if (port->xmit_buf == NULL)

		port->xmit_buf = (unsigned char *)get_zeroed_page(GFP_KERNEL);

	mutex_unlock(&port->mutex);

	if (port->xmit_buf == NULL)

		return -ENOMEM;

	return 0;

}

EXPORT_SYMBOL(tty_port_alloc_xmit_buf);



void tty_port_free_xmit_buf(struct tty_port *port)

{

	mutex_lock(&port->mutex);

	if (port->xmit_buf != NULL) {

		free_page((unsigned long)port->xmit_buf);

		port->xmit_buf = NULL;

	}

	mutex_unlock(&port->mutex);

}

EXPORT_SYMBOL(tty_port_free_xmit_buf);





static char ptychar[] = "pqrstuvwxyzabcde";



/**

include/linux/tty.h

+29 −1
Original line number Diff line number Diff line
@@ -166,6 +166,29 @@ struct tty_bufhead { 


struct device;

struct signal_struct;



/*

 * Port level information. Each device keeps its own port level information

 * so provide a common structure for those ports wanting to use common support

 * routines.

 *

 * The tty port has a different lifetime to the tty so must be kept apart.

 * In addition be careful as tty -> port mappings are valid for the life

 * of the tty object but in many cases port -> tty mappings are valid only

 * until a hangup so don't use the wrong path.

 */

 

struct tty_port {

	struct tty_struct	*tty;		/* Back pointer */

	int			blocked_open;	/* Waiting to open */

	int			count;		/* Usage count */

	wait_queue_head_t	open_wait;	/* Open waiters */

	wait_queue_head_t	close_wait;	/* Close waiters */

	unsigned long		flags;		/* TTY flags ASY_*/

	struct mutex		mutex;		/* Locking */

	unsigned char		*xmit_buf;	/* Optional buffer */

};



/*

 * Where all of the state associated with a tty is kept while the tty

 * is open.  Since the termios state should be kept even if the tty
@@ -242,6 +265,7 @@ struct tty_struct { 
	spinlock_t read_lock;

	/* If the tty has a pending do_SAK, queue it here - akpm */

	struct work_struct SAK_work;

	struct tty_port *port;

};



/* tty magic number */
@@ -350,6 +374,10 @@ extern void tty_write_unlock(struct tty_struct *tty); 
extern int tty_write_lock(struct tty_struct *tty, int ndelay);

#define tty_is_writelocked(tty)  (mutex_is_locked(&tty->atomic_write_lock))



extern void tty_port_init(struct tty_port *port);

extern int tty_port_alloc_xmit_buf(struct tty_port *port);

extern void tty_port_free_xmit_buf(struct tty_port *port);







/* n_tty.c */