[PATCH 06/23] tty: add kernel-doc for tty_ldisc_ops

From: Jiri Slaby
Date: Fri Nov 26 2021 - 03:19:29 EST


tty_ldisc_ops structure was already partially 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.

And add the documentation for the members where missing too.

Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
include/linux/tty_ldisc.h | 259 +++++++++++++++++++-------------------
1 file changed, 130 insertions(+), 129 deletions(-)

diff --git a/include/linux/tty_ldisc.h b/include/linux/tty_ldisc.h
index 25f07017bbad..e0da0ba02de9 100644
--- a/include/linux/tty_ldisc.h
+++ b/include/linux/tty_ldisc.h
@@ -4,126 +4,6 @@

struct tty_struct;

-/*
- * This structure defines the interface between the tty line discipline
- * implementation 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.
- *
- * int (*open)(struct tty_struct *);
- *
- * 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.
- *
- * void (*close)(struct tty_struct *);
- *
- * 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
- *
- * void (*flush_buffer)(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.
- *
- * ssize_t (*read)(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.
- *
- * ssize_t (*write)(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. The line discipline will deliver the characters to the
- * low-level tty device for transmission, optionally performing
- * some processing on the characters first. If this function is
- * not defined, the user will receive an EIO error.
- *
- * int (*ioctl)(struct tty_struct *tty, unsigned int cmd, unsigned long arg);
- *
- * This function is called when the user requests an ioctl which
- * is not handled by the tty layer or the low-level tty driver.
- * It is intended for ioctls which affect line discpline
- * operation. Note that the search order for ioctls is (1) tty
- * layer, (2) tty low-level driver, (3) line discpline. So a
- * low-level driver can "grab" an ioctl request before the line
- * discpline has a chance to see it.
- *
- * int (*compat_ioctl)(struct tty_struct *tty, unsigned int cmd,
- * unsigned long arg);
- *
- * Process ioctl calls from 32-bit process on 64-bit system
- *
- * NOTE: only ioctls that are neither "pointer to compatible
- * structure" nor tty-generic. Something private that takes
- * an integer or a pointer to wordsize-sensitive structure
- * belongs here, but most of ldiscs will happily leave
- * it NULL.
- *
- * void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
- *
- * This function notifies the line discpline that a change has
- * been made to the termios structure.
- *
- * int (*poll)(struct tty_struct * tty, struct file * file,
- * poll_table *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.
- *
- * void (*receive_buf)(struct tty_struct *, const unsigned char *cp,
- * 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 pointer to the buffer of input
- * character received by the device. <fp> is a pointer to a
- * pointer of flag bytes which indicate whether a character was
- * received with a parity error, etc. <fp> may be NULL to indicate
- * all data received is TTY_NORMAL.
- *
- * void (*write_wakeup)(struct tty_struct *);
- *
- * 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 for transmission. If the line discpline does
- * not have any more data to send, it can just return. If the line
- * discipline does have some data to send, please arise a tasklet
- * or workqueue to do the real data transfer. Do not send data in
- * this hook, it may leads to a deadlock.
- *
- * int (*hangup)(struct tty_struct *)
- *
- * 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.
- *
- * void (*dcd_change)(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.
- *
- * int (*receive_buf2)(struct tty_struct *, const unsigned char *cp,
- * 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 pointer to the buffer of input
- * character received by the device. <fp> is a pointer to a
- * pointer of flag bytes which indicate whether a character was
- * received with a parity error, etc. <fp> may be NULL to indicate
- * all data received is TTY_NORMAL.
- * If assigned, prefer this function for automatic flow control.
- */
-
#include <linux/fs.h>
#include <linux/wait.h>
#include <linux/atomic.h>
@@ -175,7 +55,128 @@ int ldsem_down_write_nested(struct ld_semaphore *sem, int subclass,
ldsem_down_write(sem, timeout)
#endif

-
+/**
+ * struct tty_ldisc_ops - ldisc operations
+ *
+ * @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)``
+ *
+ * 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.
+ *
+ * @close: ``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
+ *
+ * @flush_buffer: ``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.
+ *
+ * @read: ``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.
+ *
+ * @write: ``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.
+ * The line discipline will deliver the characters to the low-level tty
+ * device for transmission, optionally performing some processing on the
+ * characters first. If this function is not defined, the user will
+ * receive an %EIO error.
+ *
+ * @ioctl: ``int ()(struct tty_struct *tty, unsigned int cmd,
+ * unsigned long arg)``
+ *
+ * This function is called when the user requests an ioctl which is not
+ * handled by the tty layer or the low-level tty driver. It is intended
+ * for ioctls which affect line discpline operation. Note that the search
+ * order for ioctls is (1) tty layer, (2) tty low-level driver, (3) line
+ * 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,
+ * unsigned long arg)``
+ *
+ * Process ioctl calls from 32-bit process on 64-bit system.
+ *
+ * Note that only ioctls that are neither "pointer to compatible
+ * structure" nor tty-generic. Something private that takes an integer or
+ * 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)``
+ *
+ * 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,
+ * 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)``
+ *
+ * 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.
+ *
+ * @receive_buf: ``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
+ * a pointer to the buffer of input character received by the device. @fp
+ * is a pointer to an array of flag bytes which indicate whether a
+ * 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)``
+ *
+ * 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
+ * for transmission. If the line discpline does not have any more data to
+ * send, it can just return. If the line discipline does have some data to
+ * 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)``
+ *
+ * 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)``
+ *
+ * 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
+ * pointer to the buffer of input character received by the device. @fp
+ * is a pointer to an array of flag bytes which indicate whether a
+ * character was received with a parity error, etc. @fp may be %NULL to
+ * indicate all data received is %TTY_NORMAL. If assigned, prefer this
+ * function for automatic flow control.
+ *
+ * @owner: module containting this ldisc (for reference counting)
+ *
+ * This structure defines the interface between the tty line discipline
+ * 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.
+ */
struct tty_ldisc_ops {
char *name;
int num;
@@ -183,8 +184,8 @@ struct tty_ldisc_ops {
/*
* The following routines are called from above.
*/
- int (*open)(struct tty_struct *);
- void (*close)(struct tty_struct *);
+ int (*open)(struct tty_struct *tty);
+ void (*close)(struct tty_struct *tty);
void (*flush_buffer)(struct tty_struct *tty);
ssize_t (*read)(struct tty_struct *tty, struct file *file,
unsigned char *buf, size_t nr,
@@ -196,18 +197,18 @@ struct tty_ldisc_ops {
int (*compat_ioctl)(struct tty_struct *tty, unsigned int cmd,
unsigned long arg);
void (*set_termios)(struct tty_struct *tty, struct ktermios *old);
- __poll_t (*poll)(struct tty_struct *, struct file *,
- struct poll_table_struct *);
+ __poll_t (*poll)(struct tty_struct *tty, struct file *file,
+ struct poll_table_struct *wait);
void (*hangup)(struct tty_struct *tty);

/*
* The following routines are called from below.
*/
- void (*receive_buf)(struct tty_struct *, const unsigned char *cp,
+ void (*receive_buf)(struct tty_struct *tty, const unsigned char *cp,
const char *fp, int count);
- void (*write_wakeup)(struct tty_struct *);
- void (*dcd_change)(struct tty_struct *, unsigned int);
- int (*receive_buf2)(struct tty_struct *, const unsigned char *cp,
+ void (*write_wakeup)(struct tty_struct *tty);
+ void (*dcd_change)(struct tty_struct *tty, unsigned int status);
+ int (*receive_buf2)(struct tty_struct *tty, const unsigned char *cp,
const char *fp, int count);

struct module *owner;
--
2.34.0