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tty: combine tty_ldisc_ops docs into kernel-doc

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In Documentation/driver-api/serial/tty.rst, there are duplicated texts
about some struct tty_ldisc_ops' hooks. Combine them into existing
kernel-doc comments of struct tty_ldisc_ops and drop them from the
Documentation/.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20211126081611.11001-9-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiri Slaby 2021-11-26 09:15:56 +01:00 committed by Greg Kroah-Hartman
parent 29d5ef6859
commit 40f4268cdd
2 changed files with 45 additions and 117 deletions
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95
Documentation/driver-api/serial/tty.rst
View File

@ -35,99 +35,8 @@ about to enter and exit although this detail matters not).
Line Discipline Methods
-----------------------
TTY side interfaces
^^^^^^^^^^^^^^^^^^^
======================= =======================================================
open() Called when the line discipline is attached to
the terminal. No other call into the line
discipline for this tty will occur until it
completes successfully. Should initialize any
state needed by the ldisc, and set receive_room
in the tty_struct to the maximum amount of data
the line discipline is willing to accept from the
driver with a single call to receive_buf().
Returning an error will prevent the ldisc from
being attached. Can sleep.
close() This is called on a terminal when the line
discipline is being unplugged. At the point of
execution no further users will enter the
ldisc code for this tty. Can sleep.
hangup() Called when the tty line is hung up.
The line discipline should cease I/O to the tty.
No further calls into the ldisc code will occur.
Can sleep.
read() (optional) A process requests reading data from
the line. Multiple read calls may occur in parallel
and the ldisc must deal with serialization issues.
If not defined, the process will receive an EIO
error. May sleep.
write() (optional) A process requests writing data to the
line. Multiple write calls are serialized by the
tty layer for the ldisc. If not defined, the
process will receive an EIO error. May sleep.
flush_buffer() (optional) May be called at any point between
open and close, and instructs the line discipline
to empty its input buffer.
set_termios() (optional) Called on termios structure changes.
The caller passes the old termios data and the
current data is in the tty. Called under the
termios semaphore so allowed to sleep. Serialized
against itself only.
poll() (optional) Check the status for the poll/select
calls. Multiple poll calls may occur in parallel.
May sleep.
ioctl() (optional) Called when an ioctl is handed to the
tty layer that might be for the ldisc. Multiple
ioctl calls may occur in parallel. May sleep.
compat_ioctl() (optional) Called when a 32 bit ioctl is handed
to the tty layer that might be for the ldisc.
Multiple ioctl calls may occur in parallel.
May sleep.
======================= =======================================================
Driver Side Interfaces
^^^^^^^^^^^^^^^^^^^^^^
======================= =======================================================
receive_buf() (optional) Called by the low-level driver to hand
a buffer of received bytes to the ldisc for
processing. The number of bytes is guaranteed not
to exceed the current value of tty->receive_room.
All bytes must be processed.
receive_buf2() (optional) Called by the low-level driver to hand
a buffer of received bytes to the ldisc for
processing. Returns the number of bytes processed.
If both receive_buf() and receive_buf2() are
defined, receive_buf2() should be preferred.
write_wakeup() May be called at any point between open and close.
The TTY_DO_WRITE_WAKEUP flag indicates if a call
is needed but always races versus calls. Thus the
ldisc must be careful about setting order and to
handle unexpected calls. Must not sleep.
The driver is forbidden from calling this directly
from the ->write call from the ldisc as the ldisc
is permitted to call the driver write method from
this function. In such a situation defer it.
dcd_change() Report to the tty line the current DCD pin status
changes and the relative timestamp. The timestamp
cannot be NULL.
======================= =======================================================
.. kernel-doc:: include/linux/tty_ldisc.h
:identifiers: tty_ldisc_ops
Driver Access
^^^^^^^^^^^^^

67
include/linux/tty_ldisc.h
View File

@ -61,33 +61,45 @@ int ldsem_down_write_nested(struct ld_semaphore *sem, int subclass,
* @name: name of this ldisc rendered in /proc/tty/ldiscs
* @num: ``N_*`` number (%N_TTY, %N_HDLC, ...) reserved to this ldisc
*
* @open: ``int ()(struct tty_struct *tty)``
* @open: [TTY] ``int ()(struct tty_struct *tty)``
*
* This function is called when the line discipline is associated with the
* @tty. The line discipline can use this as an opportunity to initialize
* any state needed by the ldisc routines.
* @tty. No other call into the line discipline for this tty will occur
* until it completes successfully. It should initialize any state needed
* by the ldisc, and set @tty->receive_room to the maximum amount of data
* the line discipline is willing to accept from the driver with a single
* call to @receive_buf(). Returning an error will prevent the ldisc from
* being attached.
*
* @close: ``void ()(struct tty_struct *tty)``
* Can sleep.
*
* @close: [TTY] ``void ()(struct tty_struct *tty)``
*
* This function is called when the line discipline is being shutdown,
* either because the @tty is being closed or because the @tty is being
* changed to use a new line discipline
* changed to use a new line discipline. At the point of execution no
* further users will enter the ldisc code for this tty.
*
* @flush_buffer: ``void ()(struct tty_struct *tty)``
* Can sleep.
*
* @flush_buffer: [TTY] ``void ()(struct tty_struct *tty)``
*
* This function instructs the line discipline to clear its buffers of any
* input characters it may have queued to be delivered to the user mode
* process.
* process. It may be called at any point between open and close.
*
* @read: ``ssize_t ()(struct tty_struct *tty, struct file *file,
* @read: [TTY] ``ssize_t ()(struct tty_struct *tty, struct file *file,
* unsigned char *buf, size_t nr)``
*
* This function is called when the user requests to read from the @tty.
* The line discipline will return whatever characters it has buffered up
* for the user. If this function is not defined, the user will receive
* an %EIO error.
* an %EIO error. Multiple read calls may occur in parallel and the ldisc
* must deal with serialization issues.
*
* @write: ``ssize_t ()(struct tty_struct *tty, struct file *file,
* Can sleep.
*
* @write: [TTY] ``ssize_t ()(struct tty_struct *tty, struct file *file,
* const unsigned char *buf, size_t nr)``
*
* This function is called when the user requests to write to the @tty.
@ -96,7 +108,9 @@ int ldsem_down_write_nested(struct ld_semaphore *sem, int subclass,
* characters first. If this function is not defined, the user will
* receive an %EIO error.
*
* @ioctl: ``int ()(struct tty_struct *tty, unsigned int cmd,
* Can sleep.
*
* @ioctl: [TTY] ``int ()(struct tty_struct *tty, unsigned int cmd,
* unsigned long arg)``
*
* This function is called when the user requests an ioctl which is not
@ -106,7 +120,7 @@ int ldsem_down_write_nested(struct ld_semaphore *sem, int subclass,
* discpline. So a low-level driver can "grab" an ioctl request before
* the line discpline has a chance to see it.
*
* @compat_ioctl: ``int ()(struct tty_struct *tty, unsigned int cmd,
* @compat_ioctl: [TTY] ``int ()(struct tty_struct *tty, unsigned int cmd,
* unsigned long arg)``
*
* Process ioctl calls from 32-bit process on 64-bit system.
@ -116,27 +130,29 @@ int ldsem_down_write_nested(struct ld_semaphore *sem, int subclass,
* a pointer to wordsize-sensitive structure belongs here, but most of
* ldiscs will happily leave it %NULL.
*
* @set_termios: ``void ()(struct tty_struct *tty, struct ktermios *old)``
* @set_termios: [TTY] ``void ()(struct tty_struct *tty, struct ktermios *old)``
*
* This function notifies the line discpline that a change has been made
* to the termios structure.
*
* @poll: ``int ()(struct tty_struct *tty, struct file *file,
* @poll: [TTY] ``int ()(struct tty_struct *tty, struct file *file,
* struct poll_table_struct *wait)``
*
* This function is called when a user attempts to select/poll on a @tty
* device. It is solely the responsibility of the line discipline to
* handle poll requests.
*
* @hangup: ``void ()(struct tty_struct *tty)``
* @hangup: [TTY] ``void ()(struct tty_struct *tty)``
*
* Called on a hangup. Tells the discipline that it should cease I/O to
* the tty driver. Can sleep. The driver should seek to perform this
* action quickly but should wait until any pending driver I/O is
* completed.
* the tty driver. The driver should seek to perform this action quickly
* but should wait until any pending driver I/O is completed. No further
* calls into the ldisc code will occur.
*
* @receive_buf: ``void ()(struct tty_struct *tty, const unsigned char *cp,
* const char *fp, int count)``
* Can sleep.
*
* @receive_buf: [DRV] ``void ()(struct tty_struct *tty,
* const unsigned char *cp, const char *fp, int count)``
*
* This function is called by the low-level tty driver to send characters
* received by the hardware to the line discpline for processing. @cp is
@ -145,7 +161,7 @@ int ldsem_down_write_nested(struct ld_semaphore *sem, int subclass,
* character was received with a parity error, etc. @fp may be %NULL to
* indicate all data received is %TTY_NORMAL.
*
* @write_wakeup: ``void ()(struct tty_struct *tty)``
* @write_wakeup: [DRV] ``void ()(struct tty_struct *tty)``
*
* This function is called by the low-level tty driver to signal that line
* discpline should try to send more characters to the low-level driver
@ -154,13 +170,13 @@ int ldsem_down_write_nested(struct ld_semaphore *sem, int subclass,
* send, please arise a tasklet or workqueue to do the real data transfer.
* Do not send data in this hook, it may lead to a deadlock.
*
* @dcd_change: ``void ()(struct tty_struct *tty, unsigned int status)``
* @dcd_change: [DRV] ``void ()(struct tty_struct *tty, unsigned int status)``
*
* Tells the discipline that the DCD pin has changed its status. Used
* exclusively by the %N_PPS (Pulse-Per-Second) line discipline.
*
* @receive_buf2: ``int ()(struct tty_struct *tty, const unsigned char *cp,
* const char *fp, int count)``
* @receive_buf2: [DRV] ``int ()(struct tty_struct *tty,
* const unsigned char *cp, const char *fp, int count)``
*
* This function is called by the low-level tty driver to send characters
* received by the hardware to the line discpline for processing. @cp is a
@ -176,6 +192,9 @@ int ldsem_down_write_nested(struct ld_semaphore *sem, int subclass,
* implementation and the tty routines. The above routines can be defined.
* Unless noted otherwise, they are optional, and can be filled in with a %NULL
* pointer.
*
* Hooks marked [TTY] are invoked from the TTY core, the [DRV] ones from the
* tty_driver side.
*/
struct tty_ldisc_ops {
char *name;