tty: fix up and plug in tty_ioctl kernel-doc

The ioctl helpers are well documented, except they are not plugged in
the Documentation. So fix up the minor issues in the kernel-doc and plug
it in.

The minor issues include:
* bad \t on every line (sphinx misinterprets the description otherwise)
* missing colon after Return
* superfluous \n after the comment
* make some struct members and constants a hyperlink
* and so on

Perhaps better to use --word-diff if one wants to see the "real"
changes.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20230919085156.1578-9-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/driver-api/tty/index.rst

@@ -36,6 +36,7 @@ In-detail description of the named TTY structures is in separate documents:
    tty_struct
    tty_ldisc
    tty_buffer
+   tty_ioctl
    tty_internals
 
 Writing TTY Driver

Documentation/driver-api/tty/tty_ioctl.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+=================
+TTY IOCTL Helpers
+=================
+
+.. kernel-doc:: drivers/tty/tty_ioctl.c

drivers/tty/tty_ioctl.c

@@ -38,16 +38,13 @@
 #define TERMIOS_TERMIO	BIT(2)
 #define TERMIOS_OLD	BIT(3)
 
-
 /**
  * tty_chars_in_buffer - characters pending
  * @tty: terminal
  *
- *	Return the number of bytes of data in the device private
- *	output queue. If no private method is supplied there is assumed
- *	to be no queue on the device.
+ * Returns: the number of bytes of data in the device private output queue. If
+ * no private method is supplied there is assumed to be no queue on the device.
  */
-
 unsigned int tty_chars_in_buffer(struct tty_struct *tty)
 {
 	if (tty->ops->chars_in_buffer)
@@ -60,13 +57,12 @@ EXPORT_SYMBOL(tty_chars_in_buffer);
  * tty_write_room - write queue space
  * @tty: terminal
  *
- *	Return the number of bytes that can be queued to this device
- *	at the present time. The result should be treated as a guarantee
- *	and the driver cannot offer a value it later shrinks by more than
- *	the number of bytes written. If no method is provided 2K is always
- *	returned and data may be lost as there will be no flow control.
+ * Returns: the number of bytes that can be queued to this device at the present
+ * time. The result should be treated as a guarantee and the driver cannot
+ * offer a value it later shrinks by more than the number of bytes written. If
+ * no method is provided, 2K is always returned and data may be lost as there
+ * will be no flow control.
  */
- 
 unsigned int tty_write_room(struct tty_struct *tty)
 {
 	if (tty->ops->write_room)
@@ -79,9 +75,9 @@ EXPORT_SYMBOL(tty_write_room);
  * tty_driver_flush_buffer - discard internal buffer
  * @tty: terminal
  *
- *	Discard the internal output buffer for this device. If no method
- *	is provided then either the buffer cannot be hardware flushed or
- *	there is no buffer driver side.
+ * Discard the internal output buffer for this device. If no method is provided,
+ * then either the buffer cannot be hardware flushed or there is no buffer
+ * driver side.
  */
 void tty_driver_flush_buffer(struct tty_struct *tty)
 {
@@ -94,15 +90,14 @@ EXPORT_SYMBOL(tty_driver_flush_buffer);
  * tty_unthrottle - flow control
  * @tty: terminal
  *
- *	Indicate that a tty may continue transmitting data down the stack.
- *	Takes the termios rwsem to protect against parallel throttle/unthrottle
- *	and also to ensure the driver can consistently reference its own
- *	termios data at this point when implementing software flow control.
+ * Indicate that a @tty may continue transmitting data down the stack. Takes
+ * the &tty_struct->termios_rwsem to protect against parallel
+ * throttle/unthrottle and also to ensure the driver can consistently reference
+ * its own termios data at this point when implementing software flow control.
  *
- *	Drivers should however remember that the stack can issue a throttle,
- *	then change flow control method, then unthrottle.
+ * Drivers should however remember that the stack can issue a throttle, then
+ * change flow control method, then unthrottle.
  */
-
 void tty_unthrottle(struct tty_struct *tty)
 {
 	down_write(&tty->termios_rwsem);
@@ -118,13 +113,12 @@ EXPORT_SYMBOL(tty_unthrottle);
  * tty_throttle_safe - flow control
  * @tty: terminal
  *
- *	Indicate that a tty should stop transmitting data down the stack.
- *	tty_throttle_safe will only attempt throttle if tty->flow_change is
- *	TTY_THROTTLE_SAFE. Prevents an accidental throttle due to race
- *	conditions when throttling is conditional on factors evaluated prior to
- *	throttling.
+ * Indicate that a @tty should stop transmitting data down the stack.
+ * tty_throttle_safe() will only attempt throttle if @tty->flow_change is
+ * %TTY_THROTTLE_SAFE. Prevents an accidental throttle due to race conditions
+ * when throttling is conditional on factors evaluated prior to throttling.
  *
- *	Returns true if tty is throttled (or was already throttled)
+ * Returns: %true if @tty is throttled (or was already throttled)
  */
 bool tty_throttle_safe(struct tty_struct *tty)
 {
@@ -149,12 +143,12 @@ bool tty_throttle_safe(struct tty_struct *tty)
  * tty_unthrottle_safe - flow control
  * @tty: terminal
  *
- *	Similar to tty_unthrottle() but will only attempt unthrottle
- *	if tty->flow_change is TTY_UNTHROTTLE_SAFE. Prevents an accidental
- *	unthrottle due to race conditions when unthrottling is conditional
- *	on factors evaluated prior to unthrottling.
+ * Similar to tty_unthrottle() but will only attempt unthrottle if
+ * @tty->flow_change is %TTY_UNTHROTTLE_SAFE. Prevents an accidental unthrottle
+ * due to race conditions when unthrottling is conditional on factors evaluated
+ * prior to unthrottling.
  *
- *	Returns true if tty is unthrottled (or was already unthrottled)
+ * Returns: %true if @tty is unthrottled (or was already unthrottled)
  */
 bool tty_unthrottle_safe(struct tty_struct *tty)
 {
@@ -180,8 +174,8 @@ bool tty_unthrottle_safe(struct tty_struct *tty)
  * @tty: tty we are waiting for
  * @timeout: how long we will wait
  *
- *	Wait for characters pending in a tty driver to hit the wire, or
- *	for a timeout to occur (eg due to flow control)
+ * Wait for characters pending in a tty driver to hit the wire, or for a
+ * timeout to occur (eg due to flow control).
  *
  * Locking: none
  */
@@ -230,15 +224,14 @@ static void unset_locked_termios(struct tty_struct *tty, const struct ktermios *
 
 /**
  * tty_termios_copy_hw - copy hardware settings
- *	@new: New termios
- *	@old: Old termios
+ * @new: new termios
+ * @old: old termios
  *
- *	Propagate the hardware specific terminal setting bits from
- *	the old termios structure to the new one. This is used in cases
- *	where the hardware does not support reconfiguration or as a helper
- *	in some cases where only minimal reconfiguration is supported
+ * Propagate the hardware specific terminal setting bits from the @old termios
+ * structure to the @new one. This is used in cases where the hardware does not
+ * support reconfiguration or as a helper in some cases where only minimal
+ * reconfiguration is supported.
  */
-
 void tty_termios_copy_hw(struct ktermios *new, const struct ktermios *old)
 {
 	/* The bits a dumb device handles in software. Smart devices need
@@ -255,10 +248,11 @@ EXPORT_SYMBOL(tty_termios_copy_hw);
  * @a: termios
  * @b: termios to compare
  *
- *	Check if any of the bits that affect a dumb device have changed
- *	between the two termios structures, or a speed change is needed.
+ * Check if any of the bits that affect a dumb device have changed between the
+ * two termios structures, or a speed change is needed.
+ *
+ * Returns: %true if change is needed
  */
-
 bool tty_termios_hw_change(const struct ktermios *a, const struct ktermios *b)
 {
 	if (a->c_ispeed != b->c_ispeed || a->c_ospeed != b->c_ospeed)
@@ -273,8 +267,7 @@ EXPORT_SYMBOL(tty_termios_hw_change);
  * tty_get_char_size - get size of a character
  * @cflag: termios cflag value
  *
- *	Get the size (in bits) of a character depending on @cflag's %CSIZE
- *	setting.
+ * Returns: size (in bits) of a character depending on @cflag's %CSIZE setting
  */
 unsigned char tty_get_char_size(unsigned int cflag)
 {
@@ -296,10 +289,11 @@ EXPORT_SYMBOL_GPL(tty_get_char_size);
  * tty_get_frame_size - get size of a frame
  * @cflag: termios cflag value
  *
- *	Get the size (in bits) of a frame depending on @cflag's %CSIZE, %CSTOPB,
- *	and %PARENB setting. The result is a sum of character size, start and
- *	stop bits -- one bit each -- second stop bit (if set), and parity bit
- *	(if set).
+ * Get the size (in bits) of a frame depending on @cflag's %CSIZE, %CSTOPB, and
+ * %PARENB setting. The result is a sum of character size, start and stop bits
+ * -- one bit each -- second stop bit (if set), and parity bit (if set).
+ *
+ * Returns: size (in bits) of a frame depending on @cflag's setting.
  */
 unsigned char tty_get_frame_size(unsigned int cflag)
 {
@@ -321,12 +315,11 @@ EXPORT_SYMBOL_GPL(tty_get_frame_size);
  * @tty: tty to update
  * @new_termios: desired new value
  *
- *	Perform updates to the termios values set on this terminal.
- *	A master pty's termios should never be set.
+ * Perform updates to the termios values set on this @tty. A master pty's
+ * termios should never be set.
  *
- *	Locking: termios_rwsem
+ * Locking: &tty_struct->termios_rwsem
  */
-
 int tty_set_termios(struct tty_struct *tty, struct ktermios *new_termios)
 {
 	struct ktermios old_termios;
@@ -444,13 +437,14 @@ __weak int kernel_termios_to_user_termios(struct termios __user *u,
  * @arg: user data
  * @opt: option information
  *
- *	Helper function to prepare termios data and run necessary other
- *	functions before using tty_set_termios to do the actual changes.
+ * Helper function to prepare termios data and run necessary other functions
+ * before using tty_set_termios() to do the actual changes.
  *
- *	Locking:
- *		Called functions take ldisc and termios_rwsem locks
+ * Locking: called functions take &tty_struct->ldisc_sem and
+ * &tty_struct->termios_rwsem locks
+ *
+ * Returns: 0 on success, an error otherwise
  */
-
 static int set_termios(struct tty_struct *tty, void __user *arg, int opt)
 {
 	struct ktermios tmp_termios;
@@ -626,12 +620,12 @@ static void set_sgflags(struct ktermios *termios, int flags)
  * @tty: tty structure
  * @sgttyb: pointer to old style terminal structure
  *
- *	Updates a terminal from the legacy BSD style terminal information
- *	structure.
+ * Updates a terminal from the legacy BSD style terminal information structure.
+ *
+ * Locking: &tty_struct->termios_rwsem
  *
- *	Locking: termios_rwsem
+ * Returns: 0 on success, an error otherwise
  */
-
 static int set_sgttyb(struct tty_struct *tty, struct sgttyb __user *sgttyb)
 {
 	int retval;
@@ -735,12 +729,15 @@ static int set_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)
 /**
  * tty_change_softcar - carrier change ioctl helper
  * @tty: tty to update
- *	@enable: enable/disable CLOCAL
+ * @enable: enable/disable %CLOCAL
+ *
+ * Perform a change to the %CLOCAL state and call into the driver layer to make
+ * it visible.
  *
- *	Perform a change to the CLOCAL state and call into the driver
- *	layer to make it visible. All done with the termios rwsem
+ * Locking: &tty_struct->termios_rwsem.
+ *
+ * Returns: 0 on success, an error otherwise
  */
-
 static int tty_change_softcar(struct tty_struct *tty, bool enable)
 {
 	int ret = 0;
@@ -765,11 +762,10 @@ static int tty_change_softcar(struct tty_struct *tty, bool enable)
  * @cmd: command
  * @arg: ioctl argument
  *
- *	Perform non line discipline specific mode control ioctls. This
- *	is designed to be called by line disciplines to ensure they provide
- *	consistent mode setting.
+ * Perform non-line discipline specific mode control ioctls. This is designed
+ * to be called by line disciplines to ensure they provide consistent mode
+ * setting.
  */
-
 int tty_mode_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
 {
 	struct tty_struct *real_tty;