290 lines
10 KiB
C
290 lines
10 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef _LINUX_TTY_LDISC_H
|
|
#define _LINUX_TTY_LDISC_H
|
|
|
|
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>
|
|
|
|
/*
|
|
* the semaphore definition
|
|
*/
|
|
struct ld_semaphore {
|
|
atomic_long_t count;
|
|
raw_spinlock_t wait_lock;
|
|
unsigned int wait_readers;
|
|
struct list_head read_wait;
|
|
struct list_head write_wait;
|
|
#ifdef CONFIG_DEBUG_LOCK_ALLOC
|
|
struct lockdep_map dep_map;
|
|
#endif
|
|
};
|
|
|
|
void __init_ldsem(struct ld_semaphore *sem, const char *name,
|
|
struct lock_class_key *key);
|
|
|
|
#define init_ldsem(sem) \
|
|
do { \
|
|
static struct lock_class_key __key; \
|
|
\
|
|
__init_ldsem((sem), #sem, &__key); \
|
|
} while (0)
|
|
|
|
|
|
int ldsem_down_read(struct ld_semaphore *sem, long timeout);
|
|
int ldsem_down_read_trylock(struct ld_semaphore *sem);
|
|
int ldsem_down_write(struct ld_semaphore *sem, long timeout);
|
|
int ldsem_down_write_trylock(struct ld_semaphore *sem);
|
|
void ldsem_up_read(struct ld_semaphore *sem);
|
|
void ldsem_up_write(struct ld_semaphore *sem);
|
|
|
|
#ifdef CONFIG_DEBUG_LOCK_ALLOC
|
|
int ldsem_down_read_nested(struct ld_semaphore *sem, int subclass,
|
|
long timeout);
|
|
int ldsem_down_write_nested(struct ld_semaphore *sem, int subclass,
|
|
long timeout);
|
|
#else
|
|
# define ldsem_down_read_nested(sem, subclass, timeout) \
|
|
ldsem_down_read(sem, timeout)
|
|
# define ldsem_down_write_nested(sem, subclass, timeout) \
|
|
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: [TTY] ``int ()(struct tty_struct *tty)``
|
|
*
|
|
* This function is called when the line discipline is associated with the
|
|
* @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.
|
|
*
|
|
* Optional. 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. At the point of execution no
|
|
* further users will enter the ldisc code for this tty.
|
|
*
|
|
* Optional. 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. It may be called at any point between open and close.
|
|
*
|
|
* Optional.
|
|
*
|
|
* @read: [TTY] ``ssize_t ()(struct tty_struct *tty, struct file *file, u8 *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. Multiple read calls may occur in parallel and the ldisc
|
|
* must deal with serialization issues.
|
|
*
|
|
* Optional: %EIO unless provided. Can sleep.
|
|
*
|
|
* @write: [TTY] ``ssize_t ()(struct tty_struct *tty, struct file *file,
|
|
* const u8 *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.
|
|
*
|
|
* Optional: %EIO unless provided. 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
|
|
* 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.
|
|
*
|
|
* Optional.
|
|
*
|
|
* @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.
|
|
*
|
|
* 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.
|
|
*
|
|
* Optional.
|
|
*
|
|
* @set_termios: [TTY] ``void ()(struct tty_struct *tty, const struct ktermios *old)``
|
|
*
|
|
* This function notifies the line discpline that a change has been made
|
|
* to the termios structure.
|
|
*
|
|
* Optional.
|
|
*
|
|
* @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.
|
|
*
|
|
* Optional.
|
|
*
|
|
* @hangup: [TTY] ``void ()(struct tty_struct *tty)``
|
|
*
|
|
* Called on a hangup. Tells the discipline that it should cease I/O to
|
|
* 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.
|
|
*
|
|
* Optional. Can sleep.
|
|
*
|
|
* @receive_buf: [DRV] ``void ()(struct tty_struct *tty, const u8 *cp,
|
|
* const u8 *fp, size_t 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.
|
|
*
|
|
* Optional.
|
|
*
|
|
* @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
|
|
* 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.
|
|
*
|
|
* Optional.
|
|
*
|
|
* @dcd_change: [DRV] ``void ()(struct tty_struct *tty, bool active)``
|
|
*
|
|
* Tells the discipline that the DCD pin has changed its status. Used
|
|
* exclusively by the %N_PPS (Pulse-Per-Second) line discipline.
|
|
*
|
|
* Optional.
|
|
*
|
|
* @receive_buf2: [DRV] ``ssize_t ()(struct tty_struct *tty, const u8 *cp,
|
|
* const u8 *fp, size_t 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.
|
|
*
|
|
* Optional.
|
|
*
|
|
* @lookahead_buf: [DRV] ``void ()(struct tty_struct *tty, const u8 *cp,
|
|
* const u8 *fp, size_t count)``
|
|
*
|
|
* This function is called by the low-level tty driver for characters
|
|
* not eaten by ->receive_buf() or ->receive_buf2(). It is useful for
|
|
* processing high-priority characters such as software flow-control
|
|
* characters that could otherwise get stuck into the intermediate
|
|
* buffer until tty has room to receive them. Ldisc must be able to
|
|
* handle later a ->receive_buf() or ->receive_buf2() call for the
|
|
* same characters (e.g. by skipping the actions for high-priority
|
|
* characters already handled by ->lookahead_buf()).
|
|
*
|
|
* Optional.
|
|
*
|
|
* @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.
|
|
*
|
|
* Hooks marked [TTY] are invoked from the TTY core, the [DRV] ones from the
|
|
* tty_driver side.
|
|
*/
|
|
struct tty_ldisc_ops {
|
|
char *name;
|
|
int num;
|
|
|
|
/*
|
|
* The following routines are called from above.
|
|
*/
|
|
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, u8 *buf,
|
|
size_t nr, void **cookie, unsigned long offset);
|
|
ssize_t (*write)(struct tty_struct *tty, struct file *file,
|
|
const u8 *buf, size_t nr);
|
|
int (*ioctl)(struct tty_struct *tty, unsigned int cmd,
|
|
unsigned long arg);
|
|
int (*compat_ioctl)(struct tty_struct *tty, unsigned int cmd,
|
|
unsigned long arg);
|
|
void (*set_termios)(struct tty_struct *tty, const struct ktermios *old);
|
|
__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 *tty, const u8 *cp,
|
|
const u8 *fp, size_t count);
|
|
void (*write_wakeup)(struct tty_struct *tty);
|
|
void (*dcd_change)(struct tty_struct *tty, bool active);
|
|
size_t (*receive_buf2)(struct tty_struct *tty, const u8 *cp,
|
|
const u8 *fp, size_t count);
|
|
void (*lookahead_buf)(struct tty_struct *tty, const u8 *cp,
|
|
const u8 *fp, size_t count);
|
|
|
|
struct module *owner;
|
|
};
|
|
|
|
struct tty_ldisc {
|
|
struct tty_ldisc_ops *ops;
|
|
struct tty_struct *tty;
|
|
};
|
|
|
|
#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 */
|