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Date: Mon, 19 May 2008 15:50:13 +0100
From: Alan Cox <alan@...rguk.ukuu.org.uk>
To: linux-kernel@...r.kernel.org, akpm@...l.org, greg@...ah.com
Subject: [PATCH 01/20] tty: Introduce a tty_port common structure
From: Alan Cox <alan@...hat.com>
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.
---
drivers/char/tty_io.c | 37 +++++++++++++++++++++++++++++++++++++
include/linux/tty.h | 29 +++++++++++++++++++++++++++++
2 files changed, 66 insertions(+), 0 deletions(-)
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 49c1a22..fb17b18 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -2004,6 +2004,43 @@ 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";
/**
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 7f7121f..a5dc3e9 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -166,6 +166,30 @@ 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
@@ -241,6 +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 */
@@ -351,6 +376,10 @@ 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 */
--
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