Commit 1fe18309 authored by Jiri Slaby's avatar Jiri Slaby Committed by Greg Kroah-Hartman
Browse files

tty: add kernel-doc for tty_operations 



tty_operations structure was already documented in a standalone comment
in the header beginning.

Move it right before the structure and reformat it so it complies to
kernel-doc. That way, we can include it in Documentation/ later in this
series.

Note that we named proc_show's parameters, so that we can reference
them in the text.

Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20211126081611.11001-5-jslaby@suse.cz


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a6563830

include/linux/tty_driver.h

+241 −157
Original line number Diff line number Diff line
@@ -2,248 +2,332 @@ 
#ifndef _LINUX_TTY_DRIVER_H

#define _LINUX_TTY_DRIVER_H



/*

 * This structure defines the interface between the low-level tty

 * driver and the tty routines.  The following routines can be

 * defined; unless noted otherwise, they are optional, and can be

 * filled in with a null pointer.

#include <linux/export.h>

#include <linux/fs.h>

#include <linux/kref.h>

#include <linux/list.h>

#include <linux/cdev.h>

#include <linux/termios.h>

#include <linux/seq_file.h>



struct tty_struct;

struct tty_driver;

struct serial_icounter_struct;

struct serial_struct;



/**

 * struct tty_operations -- interface between driver and tty

 *

 * struct tty_struct * (*lookup)(struct tty_driver *self, struct file *, int idx)

 * @lookup: ``struct tty_struct *()(struct tty_driver *self, struct file *,

 *				    int idx)``

 *

 *	Return the tty device corresponding to idx, NULL if there is not

 *	one currently in use and an ERR_PTR value on error. Called under

 *	tty_mutex (for now!)

 *	Return the tty device corresponding to @idx, %NULL if there is not

 *	one currently in use and an %ERR_PTR value on error. Called under

 *	%tty_mutex (for now!)

 *

 *	Optional method. Default behaviour is to use the ttys array

 *	Optional method. Default behaviour is to use the @self->ttys array.

 *

 * int (*install)(struct tty_driver *self, struct tty_struct *tty)

 * @install: ``int ()(struct tty_driver *self, struct tty_struct *tty)``

 *

 *	Install a new tty into the tty driver internal tables. Used in

 *	conjunction with lookup and remove methods.

 *	Install a new @tty into the @self's internal tables. Used in

 *	conjunction with @lookup and @remove methods.

 *

 *	Optional method. Default behaviour is to use the ttys array

 *	Optional method. Default behaviour is to use the @self->ttys array.

 *

 * void (*remove)(struct tty_driver *self, struct tty_struct *tty)

 * @remove: ``void ()(struct tty_driver *self, struct tty_struct *tty)``

 *

 *	Remove a closed tty from the tty driver internal tables. Used in

 *	conjunction with lookup and remove methods.

 *	Remove a closed @tty from the @self's internal tables. Used in

 *	conjunction with @lookup and @remove methods.

 *

 *	Optional method. Default behaviour is to use the ttys array

 *	Optional method. Default behaviour is to use the @self->ttys array.

 *

 * int  (*open)(struct tty_struct * tty, struct file * filp);

 * @open: ``int ()(struct tty_struct *tty, struct file *)``

 *

 * 	This routine is called when a particular tty device is opened.

 * 	This routine is mandatory; if this routine is not filled in,

 * 	the attempted open will fail with ENODEV.

 *	This routine is called when a particular @tty device is opened. This

 *	routine is mandatory; if this routine is not filled in, the attempted

 *	open will fail with %ENODEV.

 *

 *	Required method. Called with tty lock held.

 *

 * void (*close)(struct tty_struct * tty, struct file * filp);

 * @close: ``void ()(struct tty_struct *tty, struct file *)``

 *

 * 	This routine is called when a particular tty device is closed.

 *	Note: called even if the corresponding open() failed.

 *	This routine is called when a particular @tty device is closed.

 *

 *	Remark: called even if the corresponding @open() failed.

 *

 *	Required method. Called with tty lock held.

 *

 * void (*shutdown)(struct tty_struct * tty);

 * @shutdown: ``void ()(struct tty_struct *tty)``

 *

 * 	This routine is called under the tty lock when a particular tty device

 *	is closed for the last time. It executes before the tty resources

 *	are freed so may execute while another function holds a tty kref.

 *	This routine is called under the tty lock when a particular @tty device

 *	is closed for the last time. It executes before the @tty resources

 *	are freed so may execute while another function holds a @tty kref.

 *

 * void (*cleanup)(struct tty_struct * tty);

 * @cleanup: ``void ()(struct tty_struct *tty)``

 *

 *	This routine is called asynchronously when a particular tty device

 *	This routine is called asynchronously when a particular @tty device

 *	is closed for the last time freeing up the resources. This is

 *	actually the second part of shutdown for routines that might sleep.

 *

 * @write: ``int ()(struct tty_struct *tty, const unsigned char *buf,

 *		    int count)``

 *

 * int (*write)(struct tty_struct * tty,

 * 		 const unsigned char *buf, int count);

 *

 * 	This routine is called by the kernel to write a series of

 * 	characters to the tty device.  The characters may come from

 *	This routine is called by the kernel to write a series (@count) of

 *	characters (@buf) to the @tty device. The characters may come from

 *	user space or kernel space.  This routine will return the

 *	number of characters actually accepted for writing.

 *

 *	Optional: Required for writable devices.

 *

 * int (*put_char)(struct tty_struct *tty, unsigned char ch);

 * @put_char: ``int ()(struct tty_struct *tty, unsigned char ch)``

 *

 * 	This routine is called by the kernel to write a single

 * 	character to the tty device.  If the kernel uses this routine,

 * 	it must call the flush_chars() routine (if defined) when it is

 * 	done stuffing characters into the driver.  If there is no room

 * 	in the queue, the character is ignored.

 *	This routine is called by the kernel to write a single character @ch to

 *	the @tty device. If the kernel uses this routine, it must call the

 *	@flush_chars() routine (if defined) when it is done stuffing characters

 *	into the driver. If there is no room in the queue, the character is

 *	ignored.

 *

 *	Optional: Kernel will use the write method if not provided.

 *	Optional: Kernel will use the @write method if not provided. Do not

 *	call this function directly, call tty_put_char().

 *

 *	Note: Do not call this function directly, call tty_put_char

 *

 * void (*flush_chars)(struct tty_struct *tty);

 * @flush_chars: ``void ()(struct tty_struct *tty)``

 *

 *	This routine is called by the kernel after it has written a

 * 	series of characters to the tty device using put_char().  

 *

 *	Optional:

 *	series of characters to the tty device using @put_char().

 *

 *	Note: Do not call this function directly, call tty_driver_flush_chars

 *	Optional. Do not call this function directly, call

 *	tty_driver_flush_chars().

 *

 * unsigned int  (*write_room)(struct tty_struct *tty);

 * @write_room: ``unsigned int ()(struct tty_struct *tty)``

 *

 * 	This routine returns the numbers of characters the tty driver

 *	This routine returns the numbers of characters the @tty driver

 *	will accept for queuing to be written.  This number is subject

 *	to change as output buffers get emptied, or if the output flow

 *	control is acted.

 *

 *	Required if write method is provided else not needed.

 *	Required if @write method is provided else not needed. Do not call this

 *	function directly, call tty_write_room()

 *

 *	Note: Do not call this function directly, call tty_write_room

 * @chars_in_buffer: ``unsigned int ()(struct tty_struct *tty)``

 *

 * int  (*ioctl)(struct tty_struct *tty, unsigned int cmd, unsigned long arg);

 *	This routine returns the number of characters in the device private

 *	output queue. Used in tty_wait_until_sent() and for poll()

 *	implementation.

 *

 * 	This routine allows the tty driver to implement

 *	device-specific ioctls.  If the ioctl number passed in cmd

 * 	is not recognized by the driver, it should return ENOIOCTLCMD.

 *	Optional: if not provided, it is assumed there is no queue on the

 *	device. Do not call this function directly, call tty_chars_in_buffer().

 *

 *	Optional

 * @ioctl: ``int ()(struct tty_struct *tty, unsigned int cmd,

 *		    unsigned long arg)``

 *

 * long (*compat_ioctl)(struct tty_struct *tty,,

 * 	                unsigned int cmd, unsigned long arg);

 *	This routine allows the @tty driver to implement device-specific

 *	ioctls. If the ioctl number passed in @cmd is not recognized by the

 *	driver, it should return %ENOIOCTLCMD.

 *

 * 	implement ioctl processing for 32 bit process on 64 bit system

 *	Optional.

 *

 *	Optional

 * @compat_ioctl: ``long ()(struct tty_struct *tty, unsigned int cmd,

 *			  unsigned long arg)``

 *

 * void (*set_termios)(struct tty_struct *tty, struct ktermios * old);

 *	Implement ioctl processing for 32 bit process on 64 bit system.

 *

 * 	This routine allows the tty driver to be notified when

 * 	device's termios settings have changed.

 *	Optional.

 *

 *	Optional: Called under the termios lock

 * @set_termios: ``void ()(struct tty_struct *tty, struct ktermios *old)``

 *

 *	This routine allows the @tty driver to be notified when device's

 *	termios settings have changed.

 *

 * void (*set_ldisc)(struct tty_struct *tty);

 *	Optional: Called under the @tty->termios_rwsem.

 *

 * 	This routine allows the tty driver to be notified when the

 * 	device's termios settings have changed.

 * @set_ldisc: ``void ()(struct tty_struct *tty)``

 *

 *	Optional: Called under BKL (currently)

 *	This routine allows the @tty driver to be notified when the device's

 *	line discipline is being changed.

 *

 * void (*throttle)(struct tty_struct * tty);

 *	Optional. Called under the @tty->ldisc_sem and @tty->termios_rwsem.

 *

 * 	This routine notifies the tty driver that input buffers for

 * 	the line discipline are close to full, and it should somehow

 * 	signal that no more characters should be sent to the tty.

 * @throttle: ``void ()(struct tty_struct *tty)``

 *

 *	Optional: Always invoke via tty_throttle_safe(), called under the

 *	termios lock.

 *	This routine notifies the @tty driver that input buffers for the line

 *	discipline are close to full, and it should somehow signal that no more

 *	characters should be sent to the @tty.

 *

 * void (*unthrottle)(struct tty_struct * tty);

 *	Optional: Always invoke via tty_throttle_safe(). Called under the

 *	@tty->termios_rwsem.

 *

 * 	This routine notifies the tty drivers that it should signals

 * 	that characters can now be sent to the tty without fear of

 * 	overrunning the input buffers of the line disciplines.

 * @unthrottle: ``void ()(struct tty_struct *tty)``

 *

 *	Optional: Always invoke via tty_unthrottle(), called under the

 *	termios lock.

 *	This routine notifies the @tty driver that it should signal that

 *	characters can now be sent to the @tty without fear of overrunning the

 *	input buffers of the line disciplines.

 *

 * void (*stop)(struct tty_struct *tty);

 *	Optional. Always invoke via tty_unthrottle(). Called under the

 *	@tty->termios_rwsem.

 *

 * 	This routine notifies the tty driver that it should stop

 * 	outputting characters to the tty device.  

 * @stop: ``void ()(struct tty_struct *tty)``

 *

 *	Called with ->flow.lock held. Serialized with start() method.

 *	This routine notifies the @tty driver that it should stop outputting

 *	characters to the tty device.

 *

 *	Optional:

 *	Called with @tty->flow.lock held. Serialized with @start() method.

 *

 *	Note: Call stop_tty not this method.

 *	Optional. Always invoke via stop_tty().

 *

 * void (*start)(struct tty_struct *tty);

 * @start: ``void ()(struct tty_struct *tty)``

 *

 * 	This routine notifies the tty driver that it resume sending

 *	characters to the tty device.

 *	This routine notifies the @tty driver that it resumed sending

 *	characters to the @tty device.

 *

 *	Called with ->flow.lock held. Serialized with stop() method.

 *	Called with @tty->flow.lock held. Serialized with stop() method.

 *

 *	Optional:

 *	Optional. Always invoke via start_tty().

 *

 *	Note: Call start_tty not this method.

 * @hangup: ``void ()(struct tty_struct *tty)``

 *

 * void (*hangup)(struct tty_struct *tty);

 *	This routine notifies the @tty driver that it should hang up the @tty

 *	device.

 *

 * 	This routine notifies the tty driver that it should hang up the

 * 	tty device.

 *	Optional. Called with tty lock held.

 *

 *	Optional:

 * @break_ctl: ``int ()(struct tty_struct *tty, int state)``

 *

 *	Called with tty lock held.

 *	This optional routine requests the @tty driver to turn on or off BREAK

 *	status on the RS-232 port. If @state is -1, then the BREAK status

 *	should be turned on; if @state is 0, then BREAK should be turned off.

 *

 * int (*break_ctl)(struct tty_struct *tty, int state);

 *	If this routine is implemented, the high-level tty driver will handle

 *	the following ioctls: %TCSBRK, %TCSBRKP, %TIOCSBRK, %TIOCCBRK.

 *

 * 	This optional routine requests the tty driver to turn on or

 * 	off BREAK status on the RS-232 port.  If state is -1,

 * 	then the BREAK status should be turned on; if state is 0, then

 * 	BREAK should be turned off.

 *	If the driver sets %TTY_DRIVER_HARDWARE_BREAK in tty_alloc_driver(),

 *	then the interface will also be called with actual times and the

 *	hardware is expected to do the delay work itself. 0 and -1 are still

 *	used for on/off.

 *

 * 	If this routine is implemented, the high-level tty driver will

 * 	handle the following ioctls: TCSBRK, TCSBRKP, TIOCSBRK,

 * 	TIOCCBRK.

 *	Optional: Required for %TCSBRK/%BRKP/etc. handling.

 *

 *	If the driver sets TTY_DRIVER_HARDWARE_BREAK then the interface

 *	will also be called with actual times and the hardware is expected

 *	to do the delay work itself. 0 and -1 are still used for on/off.

 * @flush_buffer: ``void ()(struct tty_struct *tty)``

 *

 *	Optional: Required for TCSBRK/BRKP/etc handling.

 *	This routine discards device private output buffer. Invoked on close,

 *	hangup, to implement %TCOFLUSH ioctl and similar.

 *

 * void (*wait_until_sent)(struct tty_struct *tty, int timeout);

 *	Optional: if not provided, it is assumed there is no queue on the

 *	device. Do not call this function directly, call

 *	tty_driver_flush_buffer().

 *

 * @wait_until_sent: ``void ()(struct tty_struct *tty, int timeout)``

 *

 *	This routine waits until the device has written out all of the

 * 	characters in its transmitter FIFO.

 *	characters in its transmitter FIFO. Or until @timeout (in jiffies) is

 *	reached.

 *

 *	Optional: If not provided, the device is assumed to have no FIFO.

 *	Usually correct to invoke via tty_wait_until_sent().

 *

 * @send_xchar: ``void ()(struct tty_struct *tty, char ch)``

 *

 *	This routine is used to send a high-priority XON/XOFF character (@ch)

 *	to the @tty device.

 *

 *	Optional: If not provided the device is assumed to have no FIFO

 *	Optional: If not provided, then the @write method is called under

 *	the @tty->atomic_write_lock to keep it serialized with the ldisc.

 *

 *	Note: Usually correct to call tty_wait_until_sent

 * @tiocmget: ``int ()(struct tty_struct *tty)``

 *

 * void (*send_xchar)(struct tty_struct *tty, char ch);

 *	This routine is used to obtain the modem status bits from the @tty

 *	driver.

 *

 *	Optional: If not provided, then %ENOTTY is returned from the %TIOCMGET

 *	ioctl. Do not call this function directly, call tty_tiocmget().

 *

 * 	This routine is used to send a high-priority XON/XOFF

 * 	character to the device.

 * @tiocmset: ``int ()(struct tty_struct *tty,

 *		       unsigned int set, unsigned int clear)``

 *

 *	Optional: If not provided then the write method is called under

 *	the atomic write lock to keep it serialized with the ldisc.

 *	This routine is used to set the modem status bits to the @tty driver.

 *	First, @clear bits should be cleared, then @set bits set.

 *

 * int (*resize)(struct tty_struct *tty, struct winsize *ws)

 *	Optional: If not provided, then %ENOTTY is returned from the %TIOCMSET

 *	ioctl. Do not call this function directly, call tty_tiocmset().

 *

 *	Called when a termios request is issued which changes the

 *	requested terminal geometry.

 * @resize: ``int ()(struct tty_struct *tty, struct winsize *ws)``

 *

 *	Called when a termios request is issued which changes the requested

 *	terminal geometry to @ws.

 *

 *	Optional: the default action is to update the termios structure

 *	without error. This is usually the correct behaviour. Drivers should

 *	not force errors here if they are not resizable objects (eg a serial

 *	not force errors here if they are not resizable objects (e.g. a serial

 *	line). See tty_do_resize() if you need to wrap the standard method

 *	in your own logic - the usual case.

 *	in your own logic -- the usual case.

 *

 * @get_icount: ``int ()(struct tty_struct *tty,

 *			 struct serial_icounter *icount)``

 *

 *	Called when the @tty device receives a %TIOCGICOUNT ioctl. Passed a

 *	kernel structure @icount to complete.

 *

 *	Optional: called only if provided, otherwise %ENOTTY will be returned.

 *

 * @get_serial: ``int ()(struct tty_struct *tty, struct serial_struct *p)``

 *

 *	Called when the @tty device receives a %TIOCGSERIAL ioctl. Passed a

 *	kernel structure @p (&struct serial_struct) to complete.

 *

 * int (*get_icount)(struct tty_struct *tty, struct serial_icounter *icount);

 *	Optional: called only if provided, otherwise %ENOTTY will be returned.

 *	Do not call this function directly, call tty_tiocgserial().

 *

 *	Called when the device receives a TIOCGICOUNT ioctl. Passed a kernel

 *	structure to complete. This method is optional and will only be called

 *	if provided (otherwise ENOTTY will be returned).

 * @set_serial: ``int ()(struct tty_struct *tty, struct serial_struct *p)``

 *

 *	Called when the @tty device receives a %TIOCSSERIAL ioctl. Passed a

 *	kernel structure @p (&struct serial_struct) to set the values from.

 *

 *	Optional: called only if provided, otherwise %ENOTTY will be returned.

 *	Do not call this function directly, call tty_tiocsserial().

 *

 * @show_fdinfo: ``void ()(struct tty_struct *tty, struct seq_file *m)``

 *

 *	Called when the @tty device file descriptor receives a fdinfo request

 *	from VFS (to show in /proc/<pid>/fdinfo/). @m should be filled with

 *	information.

 *

 *	Optional: called only if provided, otherwise nothing is written to @m.

 *	Do not call this function directly, call tty_show_fdinfo().

 *

 * @poll_init: ``int ()(struct tty_driver *driver, int line, char *options)``

 *

 *	kgdboc support (Documentation/dev-tools/kgdb.rst). This routine is

 *	called to initialize the HW for later use by calling @poll_get_char or

 *	@poll_put_char.

 *

 *	Optional: called only if provided, otherwise skipped as a non-polling

 *	driver.

 *

 * @poll_get_char: ``int ()(struct tty_driver *driver, int line)``

 *

 *	kgdboc support (see @poll_init). @driver should read a character from a

 *	tty identified by @line and return it.

 *

 *	Optional: called only if @poll_init provided.

 *

 * @poll_put_char: ``void ()(struct tty_driver *driver, int line, char ch)``

 *

 *	kgdboc support (see @poll_init). @driver should write character @ch to

 *	a tty identified by @line.

 *

 *	Optional: called only if @poll_init provided.

 *

 * @proc_show: ``int ()(struct seq_file *m, void *driver)``

 *

 *	Driver @driver (cast to &struct tty_driver) can show additional info in

 *	/proc/tty/driver/<driver_name>. It is enough to fill in the information

 *	into @m.

 *

 *	Optional: called only if provided, otherwise no /proc entry created.

 *

 * This structure defines the interface between the low-level tty driver and

 * the tty routines. These routines can be defined. Unless noted otherwise,

 * they are optional, and can be filled in with a %NULL pointer.

 */



#include <linux/export.h>

#include <linux/fs.h>

#include <linux/kref.h>

#include <linux/list.h>

#include <linux/cdev.h>

#include <linux/termios.h>

#include <linux/seq_file.h>



struct tty_struct;

struct tty_driver;

struct serial_icounter_struct;

struct serial_struct;



struct tty_operations {

	struct tty_struct * (*lookup)(struct tty_driver *driver,

			struct file *filp, int idx);
@@ -288,7 +372,7 @@ struct tty_operations { 
	int (*poll_get_char)(struct tty_driver *driver, int line);

	void (*poll_put_char)(struct tty_driver *driver, int line, char ch);

#endif

	int (*proc_show)(struct seq_file *, void *);

	int (*proc_show)(struct seq_file *m, void *driver);

} __randomize_layout;



/**