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tty: Introduce a tty_port common structure

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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: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Alan Cox 2008-07-16 21:53:41 +01:00 committed by Linus Torvalds
parent d87a6d951c
commit 6f67048cd0
2 changed files with 63 additions and 1 deletions
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34
drivers/char/tty_io.c
View File

@ -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";
/**

30
include/linux/tty.h
View File

@ -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
@ -214,7 +237,7 @@ struct tty_struct {
struct list_head tty_files;
#define N_TTY_BUF_SIZE 4096
/*
* The following is data for the N_TTY line discipline. For
* historical reasons, this is included in the tty structure.
@ -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 */