[PATCH 0/8] tty: split and cleanup headers

[PATCH 0/8] tty: split and cleanup headers

[Jiri Slaby]

I started writing up kernel-doc documentation of the TTY layer. It
turned out that linux/tty.h is a header containing many structures and
even function definitions. With added kernel-doc documentation for
tty_port, tty_buffer, and other main structures, tty.h grew into a very
large file.

This series moves many declarations/definitions from tty.h to places
where they fit better. For that purpose, we also create two brave new
headers to move there tty_port and tty_buffer structs.

That way, the combination of documentation and code in the headers
remains on maintainable level.

Note: this series is independent (either can be applied first) on the
other series I posted and are not applied yet.

Jiri Slaby (8):
  tty: move tty_driver related prototypes to tty_driver.h
  tty: include kref.h in tty_driver.h
  tty: move ldisc prototypes to tty_ldisc.h
  tty: include list & lockdep from tty_ldisc.h
  tty: move tty_ldisc_receive_buf to tty_flip.h
  tty: move tty_buffer definitions to new tty_buffer.h
  tty: move tty_port to new tty_port.h
  tty: tty_flip.h needs only tty_buffer and tty_port

 include/linux/tty.h        | 275 +------------------------------------
 include/linux/tty_buffer.h |  59 ++++++++
 include/linux/tty_driver.h |  18 +++
 include/linux/tty_flip.h   |   8 +-
 include/linux/tty_ldisc.h  |  17 +++
 include/linux/tty_port.h   | 208 ++++++++++++++++++++++++++++
 6 files changed, 311 insertions(+), 274 deletions(-)
 create mode 100644 include/linux/tty_buffer.h
 create mode 100644 include/linux/tty_port.h

-- 
2.32.0

[PATCH 1/8] tty: move tty_driver related prototypes to tty_driver.h

[Jiri Slaby]

We already have tty_driver.h, so cleanup tty.h a bit by moving out
tty_driver-related function prototypes into tty_driver.h.

Note that tty.h already includes tty_driver.h.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 include/linux/tty.h        | 17 -----------------
 include/linux/tty_driver.h | 17 +++++++++++++++++
 2 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/include/linux/tty.h b/include/linux/tty.h
index 19dc1097e09c..1550c1d49baa 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -446,15 +446,6 @@ extern const char *tty_driver_name(const struct tty_struct *tty);
 extern void tty_wait_until_sent(struct tty_struct *tty, long timeout);
 extern void stop_tty(struct tty_struct *tty);
 extern void start_tty(struct tty_struct *tty);
-extern int tty_register_driver(struct tty_driver *driver);
-extern void tty_unregister_driver(struct tty_driver *driver);
-extern struct device *tty_register_device(struct tty_driver *driver,
-					  unsigned index, struct device *dev);
-extern struct device *tty_register_device_attr(struct tty_driver *driver,
-				unsigned index, struct device *device,
-				void *drvdata,
-				const struct attribute_group **attr_grp);
-extern void tty_unregister_device(struct tty_driver *driver, unsigned index);
 extern void tty_write_message(struct tty_struct *tty, char *msg);
 extern int tty_send_xchar(struct tty_struct *tty, char ch);
 extern int tty_put_char(struct tty_struct *tty, unsigned char c);
@@ -691,12 +682,4 @@ extern void tty_lock_slave(struct tty_struct *tty);
 extern void tty_unlock_slave(struct tty_struct *tty);
 extern void tty_set_lock_subclass(struct tty_struct *tty);
 
-#ifdef CONFIG_PROC_FS
-extern void proc_tty_register_driver(struct tty_driver *);
-extern void proc_tty_unregister_driver(struct tty_driver *);
-#else
-static inline void proc_tty_register_driver(struct tty_driver *d) {}
-static inline void proc_tty_unregister_driver(struct tty_driver *d) {}
-#endif
-
 #endif
diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
index 448f8ee6db6e..e15f8635aa36 100644
--- a/include/linux/tty_driver.h
+++ b/include/linux/tty_driver.h
@@ -434,4 +434,21 @@ static inline struct tty_driver *tty_driver_kref_get(struct tty_driver *d)
 /* serial subtype definitions */
 #define SERIAL_TYPE_NORMAL	1
 
+int tty_register_driver(struct tty_driver *driver);
+void tty_unregister_driver(struct tty_driver *driver);
+struct device *tty_register_device(struct tty_driver *driver, unsigned index,
+		struct device *dev);
+struct device *tty_register_device_attr(struct tty_driver *driver,
+		unsigned index, struct device *device, void *drvdata,
+		const struct attribute_group **attr_grp);
+void tty_unregister_device(struct tty_driver *driver, unsigned index);
+
+#ifdef CONFIG_PROC_FS
+void proc_tty_register_driver(struct tty_driver *);
+void proc_tty_unregister_driver(struct tty_driver *);
+#else
+static inline void proc_tty_register_driver(struct tty_driver *d) {}
+static inline void proc_tty_unregister_driver(struct tty_driver *d) {}
+#endif
+
 #endif /* #ifdef _LINUX_TTY_DRIVER_H */
-- 
2.32.0

[PATCH 2/8] tty: include kref.h in tty_driver.h

[Jiri Slaby]

We use kref in tty_driver.h, but do not include kref.h. It is currently
included by linux/cdev.h -> linux/kobject.h -> linux/kref.h chain, so
everything is in order only implicitly. So make this dependency
explicit.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 include/linux/tty_driver.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
index e15f8635aa36..a798e7f8890a 100644
--- a/include/linux/tty_driver.h
+++ b/include/linux/tty_driver.h
@@ -233,6 +233,7 @@
 
 #include <linux/export.h>
 #include <linux/fs.h>
+#include <linux/kref.h>
 #include <linux/list.h>
 #include <linux/cdev.h>
 #include <linux/termios.h>
-- 
2.32.0

[PATCH 3/8] tty: move ldisc prototypes to tty_ldisc.h

[Jiri Slaby]

We already have tty_ldisc.h, so cleanup tty.h a bit by moving out
tty_ldisc-related function prototypes and a variable into tty_ldisc.h.
They are implemented in tty_ldisc.c anyway.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 include/linux/tty.h       | 10 ----------
 include/linux/tty_ldisc.h | 15 +++++++++++++++
 2 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/include/linux/tty.h b/include/linux/tty.h
index 1550c1d49baa..7f088d43db45 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -10,7 +10,6 @@
 #include <linux/tty_ldisc.h>
 #include <linux/mutex.h>
 #include <linux/tty_flags.h>
-#include <linux/seq_file.h>
 #include <uapi/linux/tty.h>
 #include <linux/rwsem.h>
 #include <linux/llist.h>
@@ -493,13 +492,7 @@ extern void tty_termios_copy_hw(struct ktermios *new, struct ktermios *old);
 extern int tty_termios_hw_change(const struct ktermios *a, const struct ktermios *b);
 extern int tty_set_termios(struct tty_struct *tty, struct ktermios *kt);
 
-extern struct tty_ldisc *tty_ldisc_ref(struct tty_struct *);
-extern void tty_ldisc_deref(struct tty_ldisc *);
-extern struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *);
-extern const struct seq_operations tty_ldiscs_seq_ops;
-
 extern void tty_wakeup(struct tty_struct *tty);
-extern void tty_ldisc_flush(struct tty_struct *tty);
 
 extern int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
 			unsigned int cmd, unsigned long arg);
@@ -629,9 +622,6 @@ static inline int tty_port_users(struct tty_port *port)
 	return port->count + port->blocked_open;
 }
 
-extern int tty_register_ldisc(struct tty_ldisc_ops *new_ldisc);
-extern void tty_unregister_ldisc(struct tty_ldisc_ops *ldisc);
-extern int tty_set_ldisc(struct tty_struct *tty, int disc);
 extern int tty_ldisc_receive_buf(struct tty_ldisc *ld, const unsigned char *p,
 				 const char *f, int count);
 
diff --git a/include/linux/tty_ldisc.h b/include/linux/tty_ldisc.h
index fbe9de278629..62131bb9251f 100644
--- a/include/linux/tty_ldisc.h
+++ b/include/linux/tty_ldisc.h
@@ -2,6 +2,8 @@
 #ifndef _LINUX_TTY_LDISC_H
 #define _LINUX_TTY_LDISC_H
 
+struct tty_struct;
+
 /*
  * This structure defines the interface between the tty line discipline
  * implementation and the tty routines.  The following routines can be
@@ -126,6 +128,7 @@
 #include <linux/fs.h>
 #include <linux/wait.h>
 #include <linux/atomic.h>
+#include <linux/seq_file.h>
 
 /*
  * the semaphore definition
@@ -220,4 +223,16 @@ struct tty_ldisc {
 #define MODULE_ALIAS_LDISC(ldisc) \
 	MODULE_ALIAS("tty-ldisc-" __stringify(ldisc))
 
+extern const struct seq_operations tty_ldiscs_seq_ops;
+
+struct tty_ldisc *tty_ldisc_ref(struct tty_struct *);
+void tty_ldisc_deref(struct tty_ldisc *);
+struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *);
+
+void tty_ldisc_flush(struct tty_struct *tty);
+
+int tty_register_ldisc(struct tty_ldisc_ops *new_ldisc);
+void tty_unregister_ldisc(struct tty_ldisc_ops *ldisc);
+int tty_set_ldisc(struct tty_struct *tty, int disc);
+
 #endif /* _LINUX_TTY_LDISC_H */
-- 
2.32.0

[PATCH 4/8] tty: include list & lockdep from tty_ldisc.h

[Jiri Slaby]

We use structs list_head and lockdep_map as non-pointers in tty_ldisc.h.
So better have headers defining them explicitly included so that the
structs are always defined. Not only implicitly via random include
chains.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 include/linux/tty_ldisc.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/tty_ldisc.h b/include/linux/tty_ldisc.h
index 62131bb9251f..b1d812e902aa 100644
--- a/include/linux/tty_ldisc.h
+++ b/include/linux/tty_ldisc.h
@@ -128,6 +128,8 @@ struct tty_struct;
 #include <linux/fs.h>
 #include <linux/wait.h>
 #include <linux/atomic.h>
+#include <linux/list.h>
+#include <linux/lockdep.h>
 #include <linux/seq_file.h>
 
 /*
-- 
2.32.0

[PATCH 5/8] tty: move tty_ldisc_receive_buf to tty_flip.h

[Jiri Slaby]

It's the only remaining tty_buffer.c prototype residing in tty.h. Move
it along others to tty_flip.h.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 include/linux/tty.h      | 3 ---
 include/linux/tty_flip.h | 5 +++++
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/include/linux/tty.h b/include/linux/tty.h
index 7f088d43db45..fad53f69a8ca 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -622,9 +622,6 @@ static inline int tty_port_users(struct tty_port *port)
 	return port->count + port->blocked_open;
 }
 
-extern int tty_ldisc_receive_buf(struct tty_ldisc *ld, const unsigned char *p,
-				 const char *f, int count);
-
 /* n_tty.c */
 extern void n_tty_inherit_ops(struct tty_ldisc_ops *ops);
 #ifdef CONFIG_TTY
diff --git a/include/linux/tty_flip.h b/include/linux/tty_flip.h
index 67d78dc553e1..615a2a87b2a7 100644
--- a/include/linux/tty_flip.h
+++ b/include/linux/tty_flip.h
@@ -4,6 +4,8 @@
 
 #include <linux/tty.h>
 
+struct tty_ldisc;
+
 extern int tty_buffer_set_limit(struct tty_port *port, int limit);
 extern unsigned int tty_buffer_space_avail(struct tty_port *port);
 extern int tty_buffer_request_room(struct tty_port *port, size_t size);
@@ -39,6 +41,9 @@ static inline int tty_insert_flip_string(struct tty_port *port,
 	return tty_insert_flip_string_fixed_flag(port, chars, TTY_NORMAL, size);
 }
 
+int tty_ldisc_receive_buf(struct tty_ldisc *ld, const unsigned char *p,
+		const char *f, int count);
+
 extern void tty_buffer_lock_exclusive(struct tty_port *port);
 extern void tty_buffer_unlock_exclusive(struct tty_port *port);
 
-- 
2.32.0

[PATCH 6/8] tty: move tty_buffer definitions to new tty_buffer.h

[Jiri Slaby]

tty.h is large enough currently. And I am slowly adding kernel-doc
documentation, so it grows to unmaintainable long mess. To avoid this,
split tty.h further into tty_buffer.h and move there tty_buffer-related
declarations and function prototypes.

Note that many of the tty_buffer.c function prototypes reside now in
tty_flip.h. But we cannot move struct tty_buffer & friends because:
* tty_insert_flip_char() in tty_flip.h needs both struct tty_port and
  struct tty_buffer defined.
* struct tty_port in tty_port.h needs struct tty_buffer defined.

So if we moved struct tty_buffer to tty_flip.h too, tty_flip.h would
need tty_port.h and that would need tty_flip.h (to have tty_buffer)
again. Hence we introduce new header tty_buffer.h here to break this
circular dependency.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 include/linux/tty.h        | 49 +------------------------------
 include/linux/tty_buffer.h | 59 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 60 insertions(+), 48 deletions(-)
 create mode 100644 include/linux/tty_buffer.h

diff --git a/include/linux/tty.h b/include/linux/tty.h
index fad53f69a8ca..b5f353797cec 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -6,6 +6,7 @@
 #include <linux/major.h>
 #include <linux/termios.h>
 #include <linux/workqueue.h>
+#include <linux/tty_buffer.h>
 #include <linux/tty_driver.h>
 #include <linux/tty_ldisc.h>
 #include <linux/mutex.h>
@@ -30,54 +31,6 @@
  */
 #define __DISABLED_CHAR '\0'
 
-struct tty_buffer {
-	union {
-		struct tty_buffer *next;
-		struct llist_node free;
-	};
-	int used;
-	int size;
-	int commit;
-	int read;
-	int flags;
-	/* Data points here */
-	unsigned long data[];
-};
-
-/* Values for .flags field of tty_buffer */
-#define TTYB_NORMAL	1	/* buffer has no flags buffer */
-
-static inline unsigned char *char_buf_ptr(struct tty_buffer *b, int ofs)
-{
-	return ((unsigned char *)b->data) + ofs;
-}
-
-static inline char *flag_buf_ptr(struct tty_buffer *b, int ofs)
-{
-	return (char *)char_buf_ptr(b, ofs) + b->size;
-}
-
-struct tty_bufhead {
-	struct tty_buffer *head;	/* Queue head */
-	struct work_struct work;
-	struct mutex	   lock;
-	atomic_t	   priority;
-	struct tty_buffer sentinel;
-	struct llist_head free;		/* Free queue head */
-	atomic_t	   mem_used;    /* In-use buffers excluding free list */
-	int		   mem_limit;
-	struct tty_buffer *tail;	/* Active buffer */
-};
-/*
- * When a break, frame error, or parity error happens, these codes are
- * stuffed into the flags buffer.
- */
-#define TTY_NORMAL	0
-#define TTY_BREAK	1
-#define TTY_FRAME	2
-#define TTY_PARITY	3
-#define TTY_OVERRUN	4
-
 #define INTR_CHAR(tty) ((tty)->termios.c_cc[VINTR])
 #define QUIT_CHAR(tty) ((tty)->termios.c_cc[VQUIT])
 #define ERASE_CHAR(tty) ((tty)->termios.c_cc[VERASE])
diff --git a/include/linux/tty_buffer.h b/include/linux/tty_buffer.h
new file mode 100644
index 000000000000..3b9d77604291
--- /dev/null
+++ b/include/linux/tty_buffer.h
@@ -0,0 +1,59 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_TTY_BUFFER_H
+#define _LINUX_TTY_BUFFER_H
+
+#include <linux/atomic.h>
+#include <linux/llist.h>
+#include <linux/mutex.h>
+#include <linux/workqueue.h>
+
+struct tty_buffer {
+	union {
+		struct tty_buffer *next;
+		struct llist_node free;
+	};
+	int used;
+	int size;
+	int commit;
+	int read;
+	int flags;
+	/* Data points here */
+	unsigned long data[];
+};
+
+/* Values for .flags field of tty_buffer */
+#define TTYB_NORMAL	1	/* buffer has no flags buffer */
+
+static inline unsigned char *char_buf_ptr(struct tty_buffer *b, int ofs)
+{
+	return ((unsigned char *)b->data) + ofs;
+}
+
+static inline char *flag_buf_ptr(struct tty_buffer *b, int ofs)
+{
+	return (char *)char_buf_ptr(b, ofs) + b->size;
+}
+
+struct tty_bufhead {
+	struct tty_buffer *head;	/* Queue head */
+	struct work_struct work;
+	struct mutex	   lock;
+	atomic_t	   priority;
+	struct tty_buffer sentinel;
+	struct llist_head free;		/* Free queue head */
+	atomic_t	   mem_used;    /* In-use buffers excluding free list */
+	int		   mem_limit;
+	struct tty_buffer *tail;	/* Active buffer */
+};
+
+/*
+ * When a break, frame error, or parity error happens, these codes are
+ * stuffed into the flags buffer.
+ */
+#define TTY_NORMAL	0
+#define TTY_BREAK	1
+#define TTY_FRAME	2
+#define TTY_PARITY	3
+#define TTY_OVERRUN	4
+
+#endif
-- 
2.32.0

[PATCH 7/8] tty: move tty_port to new tty_port.h

[Jiri Slaby]

tty.h is long enough already. And I am slowly adding kernel-doc
documentation, so it grows to unmaintainable long mess. To avoid this,
split tty.h further into tty_port.h and move there tty_port-related
declarations and function prototypes (those implemented in tty_port.c).

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 include/linux/tty.h      | 196 +-----------------------------------
 include/linux/tty_port.h | 208 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 209 insertions(+), 195 deletions(-)
 create mode 100644 include/linux/tty_port.h

diff --git a/include/linux/tty.h b/include/linux/tty.h
index b5f353797cec..168e57e40bbb 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -9,6 +9,7 @@
 #include <linux/tty_buffer.h>
 #include <linux/tty_driver.h>
 #include <linux/tty_ldisc.h>
+#include <linux/tty_port.h>
 #include <linux/mutex.h>
 #include <linux/tty_flags.h>
 #include <uapi/linux/tty.h>
@@ -116,85 +117,6 @@
 
 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_port_operations {
-	/* Return 1 if the carrier is raised */
-	int (*carrier_raised)(struct tty_port *port);
-	/* Control the DTR line */
-	void (*dtr_rts)(struct tty_port *port, int raise);
-	/* Called when the last close completes or a hangup finishes
-	   IFF the port was initialized. Do not use to free resources. Called
-	   under the port mutex to serialize against activate/shutdowns */
-	void (*shutdown)(struct tty_port *port);
-	/* Called under the port mutex from tty_port_open, serialized using
-	   the port mutex */
-        /* FIXME: long term getting the tty argument *out* of this would be
-           good for consoles */
-	int (*activate)(struct tty_port *port, struct tty_struct *tty);
-	/* Called on the final put of a port */
-	void (*destruct)(struct tty_port *port);
-};
-
-struct tty_port_client_operations {
-	int (*receive_buf)(struct tty_port *port, const unsigned char *, const unsigned char *, size_t);
-	void (*write_wakeup)(struct tty_port *port);
-};
-
-extern const struct tty_port_client_operations tty_port_default_client_ops;
-
-struct tty_port {
-	struct tty_bufhead	buf;		/* Locked internally */
-	struct tty_struct	*tty;		/* Back pointer */
-	struct tty_struct	*itty;		/* internal back ptr */
-	const struct tty_port_operations *ops;	/* Port operations */
-	const struct tty_port_client_operations *client_ops; /* Port client operations */
-	spinlock_t		lock;		/* Lock protecting tty field */
-	int			blocked_open;	/* Waiting to open */
-	int			count;		/* Usage count */
-	wait_queue_head_t	open_wait;	/* Open waiters */
-	wait_queue_head_t	delta_msr_wait;	/* Modem status change */
-	unsigned long		flags;		/* User TTY flags ASYNC_ */
-	unsigned long		iflags;		/* Internal flags TTY_PORT_ */
-	unsigned char		console:1;	/* port is a console */
-	struct mutex		mutex;		/* Locking */
-	struct mutex		buf_mutex;	/* Buffer alloc lock */
-	unsigned char		*xmit_buf;	/* Optional buffer */
-	unsigned int		close_delay;	/* Close port delay */
-	unsigned int		closing_wait;	/* Delay for output */
-	int			drain_delay;	/* Set to zero if no pure time
-						   based drain is needed else
-						   set to size of fifo */
-	struct kref		kref;		/* Ref counter */
-	void 			*client_data;
-};
-
-/* tty_port::iflags bits -- use atomic bit ops */
-#define TTY_PORT_INITIALIZED	0	/* device is initialized */
-#define TTY_PORT_SUSPENDED	1	/* device is suspended */
-#define TTY_PORT_ACTIVE		2	/* device is open */
-
-/*
- * uart drivers: use the uart_port::status field and the UPSTAT_* defines
- * for s/w-based flow control steering and carrier detection status
- */
-#define TTY_PORT_CTS_FLOW	3	/* h/w flow control enabled */
-#define TTY_PORT_CHECK_CD	4	/* carrier detect enabled */
-#define TTY_PORT_KOPENED	5	/* device exclusively opened by
-					   kernel */
-
 struct tty_operations;
 
 /**
@@ -459,122 +381,6 @@ extern int tty_standard_install(struct tty_driver *driver,
 
 extern struct mutex tty_mutex;
 
-extern void tty_port_init(struct tty_port *port);
-extern void tty_port_link_device(struct tty_port *port,
-		struct tty_driver *driver, unsigned index);
-extern struct device *tty_port_register_device(struct tty_port *port,
-		struct tty_driver *driver, unsigned index,
-		struct device *device);
-extern struct device *tty_port_register_device_attr(struct tty_port *port,
-		struct tty_driver *driver, unsigned index,
-		struct device *device, void *drvdata,
-		const struct attribute_group **attr_grp);
-extern struct device *tty_port_register_device_serdev(struct tty_port *port,
-		struct tty_driver *driver, unsigned index,
-		struct device *device);
-extern struct device *tty_port_register_device_attr_serdev(struct tty_port *port,
-		struct tty_driver *driver, unsigned index,
-		struct device *device, void *drvdata,
-		const struct attribute_group **attr_grp);
-extern void tty_port_unregister_device(struct tty_port *port,
-		struct tty_driver *driver, unsigned index);
-extern int tty_port_alloc_xmit_buf(struct tty_port *port);
-extern void tty_port_free_xmit_buf(struct tty_port *port);
-extern void tty_port_destroy(struct tty_port *port);
-extern void tty_port_put(struct tty_port *port);
-
-static inline struct tty_port *tty_port_get(struct tty_port *port)
-{
-	if (port && kref_get_unless_zero(&port->kref))
-		return port;
-	return NULL;
-}
-
-/* If the cts flow control is enabled, return true. */
-static inline bool tty_port_cts_enabled(const struct tty_port *port)
-{
-	return test_bit(TTY_PORT_CTS_FLOW, &port->iflags);
-}
-
-static inline void tty_port_set_cts_flow(struct tty_port *port, bool val)
-{
-	assign_bit(TTY_PORT_CTS_FLOW, &port->iflags, val);
-}
-
-static inline bool tty_port_active(const struct tty_port *port)
-{
-	return test_bit(TTY_PORT_ACTIVE, &port->iflags);
-}
-
-static inline void tty_port_set_active(struct tty_port *port, bool val)
-{
-	assign_bit(TTY_PORT_ACTIVE, &port->iflags, val);
-}
-
-static inline bool tty_port_check_carrier(const struct tty_port *port)
-{
-	return test_bit(TTY_PORT_CHECK_CD, &port->iflags);
-}
-
-static inline void tty_port_set_check_carrier(struct tty_port *port, bool val)
-{
-	assign_bit(TTY_PORT_CHECK_CD, &port->iflags, val);
-}
-
-static inline bool tty_port_suspended(const struct tty_port *port)
-{
-	return test_bit(TTY_PORT_SUSPENDED, &port->iflags);
-}
-
-static inline void tty_port_set_suspended(struct tty_port *port, bool val)
-{
-	assign_bit(TTY_PORT_SUSPENDED, &port->iflags, val);
-}
-
-static inline bool tty_port_initialized(const struct tty_port *port)
-{
-	return test_bit(TTY_PORT_INITIALIZED, &port->iflags);
-}
-
-static inline void tty_port_set_initialized(struct tty_port *port, bool val)
-{
-	assign_bit(TTY_PORT_INITIALIZED, &port->iflags, val);
-}
-
-static inline bool tty_port_kopened(const struct tty_port *port)
-{
-	return test_bit(TTY_PORT_KOPENED, &port->iflags);
-}
-
-static inline void tty_port_set_kopened(struct tty_port *port, bool val)
-{
-	assign_bit(TTY_PORT_KOPENED, &port->iflags, val);
-}
-
-extern struct tty_struct *tty_port_tty_get(struct tty_port *port);
-extern void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty);
-extern int tty_port_carrier_raised(struct tty_port *port);
-extern void tty_port_raise_dtr_rts(struct tty_port *port);
-extern void tty_port_lower_dtr_rts(struct tty_port *port);
-extern void tty_port_hangup(struct tty_port *port);
-extern void tty_port_tty_hangup(struct tty_port *port, bool check_clocal);
-extern void tty_port_tty_wakeup(struct tty_port *port);
-extern int tty_port_block_til_ready(struct tty_port *port,
-				struct tty_struct *tty, struct file *filp);
-extern int tty_port_close_start(struct tty_port *port,
-				struct tty_struct *tty, struct file *filp);
-extern void tty_port_close_end(struct tty_port *port, struct tty_struct *tty);
-extern void tty_port_close(struct tty_port *port,
-				struct tty_struct *tty, struct file *filp);
-extern int tty_port_install(struct tty_port *port, struct tty_driver *driver,
-				struct tty_struct *tty);
-extern int tty_port_open(struct tty_port *port,
-				struct tty_struct *tty, struct file *filp);
-static inline int tty_port_users(struct tty_port *port)
-{
-	return port->count + port->blocked_open;
-}
-
 /* n_tty.c */
 extern void n_tty_inherit_ops(struct tty_ldisc_ops *ops);
 #ifdef CONFIG_TTY
diff --git a/include/linux/tty_port.h b/include/linux/tty_port.h
new file mode 100644
index 000000000000..6e86e9e118b6
--- /dev/null
+++ b/include/linux/tty_port.h
@@ -0,0 +1,208 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_TTY_PORT_H
+#define _LINUX_TTY_PORT_H
+
+#include <linux/kref.h>
+#include <linux/mutex.h>
+#include <linux/tty_buffer.h>
+#include <linux/wait.h>
+
+/*
+ * 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 attribute_group;
+struct tty_driver;
+struct tty_port;
+struct tty_struct;
+
+struct tty_port_operations {
+	/* Return 1 if the carrier is raised */
+	int (*carrier_raised)(struct tty_port *port);
+	/* Control the DTR line */
+	void (*dtr_rts)(struct tty_port *port, int raise);
+	/* Called when the last close completes or a hangup finishes
+	   IFF the port was initialized. Do not use to free resources. Called
+	   under the port mutex to serialize against activate/shutdowns */
+	void (*shutdown)(struct tty_port *port);
+	/* Called under the port mutex from tty_port_open, serialized using
+	   the port mutex */
+        /* FIXME: long term getting the tty argument *out* of this would be
+           good for consoles */
+	int (*activate)(struct tty_port *port, struct tty_struct *tty);
+	/* Called on the final put of a port */
+	void (*destruct)(struct tty_port *port);
+};
+
+struct tty_port_client_operations {
+	int (*receive_buf)(struct tty_port *port, const unsigned char *, const unsigned char *, size_t);
+	void (*write_wakeup)(struct tty_port *port);
+};
+
+extern const struct tty_port_client_operations tty_port_default_client_ops;
+
+struct tty_port {
+	struct tty_bufhead	buf;		/* Locked internally */
+	struct tty_struct	*tty;		/* Back pointer */
+	struct tty_struct	*itty;		/* internal back ptr */
+	const struct tty_port_operations *ops;	/* Port operations */
+	const struct tty_port_client_operations *client_ops; /* Port client operations */
+	spinlock_t		lock;		/* Lock protecting tty field */
+	int			blocked_open;	/* Waiting to open */
+	int			count;		/* Usage count */
+	wait_queue_head_t	open_wait;	/* Open waiters */
+	wait_queue_head_t	delta_msr_wait;	/* Modem status change */
+	unsigned long		flags;		/* User TTY flags ASYNC_ */
+	unsigned long		iflags;		/* Internal flags TTY_PORT_ */
+	unsigned char		console:1;	/* port is a console */
+	struct mutex		mutex;		/* Locking */
+	struct mutex		buf_mutex;	/* Buffer alloc lock */
+	unsigned char		*xmit_buf;	/* Optional buffer */
+	unsigned int		close_delay;	/* Close port delay */
+	unsigned int		closing_wait;	/* Delay for output */
+	int			drain_delay;	/* Set to zero if no pure time
+						   based drain is needed else
+						   set to size of fifo */
+	struct kref		kref;		/* Ref counter */
+	void 			*client_data;
+};
+
+/* tty_port::iflags bits -- use atomic bit ops */
+#define TTY_PORT_INITIALIZED	0	/* device is initialized */
+#define TTY_PORT_SUSPENDED	1	/* device is suspended */
+#define TTY_PORT_ACTIVE		2	/* device is open */
+
+/*
+ * uart drivers: use the uart_port::status field and the UPSTAT_* defines
+ * for s/w-based flow control steering and carrier detection status
+ */
+#define TTY_PORT_CTS_FLOW	3	/* h/w flow control enabled */
+#define TTY_PORT_CHECK_CD	4	/* carrier detect enabled */
+#define TTY_PORT_KOPENED	5	/* device exclusively opened by
+					   kernel */
+
+void tty_port_init(struct tty_port *port);
+void tty_port_link_device(struct tty_port *port, struct tty_driver *driver,
+		unsigned index);
+struct device *tty_port_register_device(struct tty_port *port,
+		struct tty_driver *driver, unsigned index,
+		struct device *device);
+struct device *tty_port_register_device_attr(struct tty_port *port,
+		struct tty_driver *driver, unsigned index,
+		struct device *device, void *drvdata,
+		const struct attribute_group **attr_grp);
+struct device *tty_port_register_device_serdev(struct tty_port *port,
+		struct tty_driver *driver, unsigned index,
+		struct device *device);
+struct device *tty_port_register_device_attr_serdev(struct tty_port *port,
+		struct tty_driver *driver, unsigned index,
+		struct device *device, void *drvdata,
+		const struct attribute_group **attr_grp);
+void tty_port_unregister_device(struct tty_port *port,
+		struct tty_driver *driver, unsigned index);
+int tty_port_alloc_xmit_buf(struct tty_port *port);
+void tty_port_free_xmit_buf(struct tty_port *port);
+void tty_port_destroy(struct tty_port *port);
+void tty_port_put(struct tty_port *port);
+
+static inline struct tty_port *tty_port_get(struct tty_port *port)
+{
+	if (port && kref_get_unless_zero(&port->kref))
+		return port;
+	return NULL;
+}
+
+/* If the cts flow control is enabled, return true. */
+static inline bool tty_port_cts_enabled(const struct tty_port *port)
+{
+	return test_bit(TTY_PORT_CTS_FLOW, &port->iflags);
+}
+
+static inline void tty_port_set_cts_flow(struct tty_port *port, bool val)
+{
+	assign_bit(TTY_PORT_CTS_FLOW, &port->iflags, val);
+}
+
+static inline bool tty_port_active(const struct tty_port *port)
+{
+	return test_bit(TTY_PORT_ACTIVE, &port->iflags);
+}
+
+static inline void tty_port_set_active(struct tty_port *port, bool val)
+{
+	assign_bit(TTY_PORT_ACTIVE, &port->iflags, val);
+}
+
+static inline bool tty_port_check_carrier(const struct tty_port *port)
+{
+	return test_bit(TTY_PORT_CHECK_CD, &port->iflags);
+}
+
+static inline void tty_port_set_check_carrier(struct tty_port *port, bool val)
+{
+	assign_bit(TTY_PORT_CHECK_CD, &port->iflags, val);
+}
+
+static inline bool tty_port_suspended(const struct tty_port *port)
+{
+	return test_bit(TTY_PORT_SUSPENDED, &port->iflags);
+}
+
+static inline void tty_port_set_suspended(struct tty_port *port, bool val)
+{
+	assign_bit(TTY_PORT_SUSPENDED, &port->iflags, val);
+}
+
+static inline bool tty_port_initialized(const struct tty_port *port)
+{
+	return test_bit(TTY_PORT_INITIALIZED, &port->iflags);
+}
+
+static inline void tty_port_set_initialized(struct tty_port *port, bool val)
+{
+	assign_bit(TTY_PORT_INITIALIZED, &port->iflags, val);
+}
+
+static inline bool tty_port_kopened(const struct tty_port *port)
+{
+	return test_bit(TTY_PORT_KOPENED, &port->iflags);
+}
+
+static inline void tty_port_set_kopened(struct tty_port *port, bool val)
+{
+	assign_bit(TTY_PORT_KOPENED, &port->iflags, val);
+}
+
+struct tty_struct *tty_port_tty_get(struct tty_port *port);
+void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty);
+int tty_port_carrier_raised(struct tty_port *port);
+void tty_port_raise_dtr_rts(struct tty_port *port);
+void tty_port_lower_dtr_rts(struct tty_port *port);
+void tty_port_hangup(struct tty_port *port);
+void tty_port_tty_hangup(struct tty_port *port, bool check_clocal);
+void tty_port_tty_wakeup(struct tty_port *port);
+int tty_port_block_til_ready(struct tty_port *port, struct tty_struct *tty,
+		struct file *filp);
+int tty_port_close_start(struct tty_port *port, struct tty_struct *tty,
+		struct file *filp);
+void tty_port_close_end(struct tty_port *port, struct tty_struct *tty);
+void tty_port_close(struct tty_port *port, struct tty_struct *tty,
+		struct file *filp);
+int tty_port_install(struct tty_port *port, struct tty_driver *driver,
+		struct tty_struct *tty);
+int tty_port_open(struct tty_port *port, struct tty_struct *tty,
+		struct file *filp);
+
+static inline int tty_port_users(struct tty_port *port)
+{
+	return port->count + port->blocked_open;
+}
+
+#endif
-- 
2.32.0

[PATCH 8/8] tty: tty_flip.h needs only tty_buffer and tty_port

[Jiri Slaby]

tty_flip.h currently includes whole tty.h. In fact, it needs only
tty_buffer and tty_port definitions. Provided, we separated tty_buffer
and tty_port into separate headers in the previous patch, we can make
tty_flip.h to include only much lighter tty_buffer.h and tty_port.h.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 include/linux/tty_flip.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/linux/tty_flip.h b/include/linux/tty_flip.h
index 615a2a87b2a7..32284992b31a 100644
--- a/include/linux/tty_flip.h
+++ b/include/linux/tty_flip.h
@@ -2,7 +2,8 @@
 #ifndef _LINUX_TTY_FLIP_H
 #define _LINUX_TTY_FLIP_H
 
-#include <linux/tty.h>
+#include <linux/tty_buffer.h>
+#include <linux/tty_port.h>
 
 struct tty_ldisc;
 
-- 
2.32.0

Re: [PATCH 0/8] tty: split and cleanup headers

[Greg KH]

On Fri, Jul 23, 2021 at 12:31:39PM +0200, Jiri Slaby wrote:
> I started writing up kernel-doc documentation of the TTY layer. It
> turned out that linux/tty.h is a header containing many structures and
> even function definitions. With added kernel-doc documentation for
> tty_port, tty_buffer, and other main structures, tty.h grew into a very
> large file.
> 
> This series moves many declarations/definitions from tty.h to places
> where they fit better. For that purpose, we also create two brave new
> headers to move there tty_port and tty_buffer structs.
> 
> That way, the combination of documentation and code in the headers
> remains on maintainable level.

Thanks for the cleanups, much appreciated, now applied.

greg k-h