222 lines
7.7 KiB
C
Executable file
222 lines
7.7 KiB
C
Executable file
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_TTY_LDISC_H
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#define _LINUX_TTY_LDISC_H
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/*
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* This structure defines the interface between the tty line discipline
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* implementation and the tty routines. The following routines can be
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* defined; unless noted otherwise, they are optional, and can be
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* filled in with a null pointer.
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*
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* int (*open)(struct tty_struct *);
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*
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* This function is called when the line discipline is associated
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* with the tty. The line discipline can use this as an
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* opportunity to initialize any state needed by the ldisc routines.
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*
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* void (*close)(struct tty_struct *);
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*
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* This function is called when the line discipline is being
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* shutdown, either because the tty is being closed or because
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* the tty is being changed to use a new line discipline
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*
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* void (*flush_buffer)(struct tty_struct *tty);
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*
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* This function instructs the line discipline to clear its
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* buffers of any input characters it may have queued to be
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* delivered to the user mode process.
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*
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* ssize_t (*read)(struct tty_struct * tty, struct file * file,
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* unsigned char * buf, size_t nr);
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*
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* This function is called when the user requests to read from
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* the tty. The line discipline will return whatever characters
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* it has buffered up for the user. If this function is not
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* defined, the user will receive an EIO error.
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*
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* ssize_t (*write)(struct tty_struct * tty, struct file * file,
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* const unsigned char * buf, size_t nr);
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*
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* This function is called when the user requests to write to the
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* tty. The line discipline will deliver the characters to the
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* low-level tty device for transmission, optionally performing
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* some processing on the characters first. If this function is
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* not defined, the user will receive an EIO error.
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*
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* int (*ioctl)(struct tty_struct * tty, struct file * file,
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* unsigned int cmd, unsigned long arg);
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*
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* This function is called when the user requests an ioctl which
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* is not handled by the tty layer or the low-level tty driver.
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* It is intended for ioctls which affect line discpline
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* operation. Note that the search order for ioctls is (1) tty
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* layer, (2) tty low-level driver, (3) line discpline. So a
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* low-level driver can "grab" an ioctl request before the line
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* discpline has a chance to see it.
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*
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* long (*compat_ioctl)(struct tty_struct * tty, struct file * file,
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* unsigned int cmd, unsigned long arg);
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*
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* Process ioctl calls from 32-bit process on 64-bit system
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*
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* void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
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*
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* This function notifies the line discpline that a change has
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* been made to the termios structure.
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*
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* int (*poll)(struct tty_struct * tty, struct file * file,
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* poll_table *wait);
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*
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* This function is called when a user attempts to select/poll on a
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* tty device. It is solely the responsibility of the line
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* discipline to handle poll requests.
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*
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* void (*receive_buf)(struct tty_struct *, const unsigned char *cp,
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* char *fp, int count);
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*
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* This function is called by the low-level tty driver to send
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* characters received by the hardware to the line discpline for
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* processing. <cp> is a pointer to the buffer of input
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* character received by the device. <fp> is a pointer to a
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* pointer of flag bytes which indicate whether a character was
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* received with a parity error, etc. <fp> may be NULL to indicate
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* all data received is TTY_NORMAL.
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*
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* void (*write_wakeup)(struct tty_struct *);
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*
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* This function is called by the low-level tty driver to signal
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* that line discpline should try to send more characters to the
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* low-level driver for transmission. If the line discpline does
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* not have any more data to send, it can just return. If the line
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* discipline does have some data to send, please arise a tasklet
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* or workqueue to do the real data transfer. Do not send data in
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* this hook, it may leads to a deadlock.
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*
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* int (*hangup)(struct tty_struct *)
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*
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* Called on a hangup. Tells the discipline that it should
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* cease I/O to the tty driver. Can sleep. The driver should
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* seek to perform this action quickly but should wait until
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* any pending driver I/O is completed.
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*
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* void (*dcd_change)(struct tty_struct *tty, unsigned int status)
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*
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* Tells the discipline that the DCD pin has changed its status.
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* Used exclusively by the N_PPS (Pulse-Per-Second) line discipline.
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*
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* int (*receive_buf2)(struct tty_struct *, const unsigned char *cp,
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* char *fp, int count);
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*
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* This function is called by the low-level tty driver to send
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* characters received by the hardware to the line discpline for
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* processing. <cp> is a pointer to the buffer of input
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* character received by the device. <fp> is a pointer to a
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* pointer of flag bytes which indicate whether a character was
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* received with a parity error, etc. <fp> may be NULL to indicate
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* all data received is TTY_NORMAL.
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* If assigned, prefer this function for automatic flow control.
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*/
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#include <linux/fs.h>
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#include <linux/wait.h>
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#include <linux/atomic.h>
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/*
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* the semaphore definition
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*/
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struct ld_semaphore {
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atomic_long_t count;
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raw_spinlock_t wait_lock;
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unsigned int wait_readers;
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struct list_head read_wait;
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struct list_head write_wait;
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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struct lockdep_map dep_map;
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#endif
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};
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extern void __init_ldsem(struct ld_semaphore *sem, const char *name,
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struct lock_class_key *key);
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#define init_ldsem(sem) \
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do { \
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static struct lock_class_key __key; \
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\
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__init_ldsem((sem), #sem, &__key); \
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} while (0)
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extern int ldsem_down_read(struct ld_semaphore *sem, long timeout);
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extern int ldsem_down_read_trylock(struct ld_semaphore *sem);
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extern int ldsem_down_write(struct ld_semaphore *sem, long timeout);
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extern int ldsem_down_write_trylock(struct ld_semaphore *sem);
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extern void ldsem_up_read(struct ld_semaphore *sem);
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extern void ldsem_up_write(struct ld_semaphore *sem);
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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extern int ldsem_down_read_nested(struct ld_semaphore *sem, int subclass,
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long timeout);
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extern int ldsem_down_write_nested(struct ld_semaphore *sem, int subclass,
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long timeout);
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#else
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# define ldsem_down_read_nested(sem, subclass, timeout) \
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ldsem_down_read(sem, timeout)
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# define ldsem_down_write_nested(sem, subclass, timeout) \
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ldsem_down_write(sem, timeout)
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#endif
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struct tty_ldisc_ops {
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int magic;
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char *name;
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int num;
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int flags;
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/*
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* The following routines are called from above.
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*/
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int (*open)(struct tty_struct *);
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void (*close)(struct tty_struct *);
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void (*flush_buffer)(struct tty_struct *tty);
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ssize_t (*read)(struct tty_struct *tty, struct file *file,
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unsigned char __user *buf, size_t nr);
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ssize_t (*write)(struct tty_struct *tty, struct file *file,
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const unsigned char *buf, size_t nr);
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int (*ioctl)(struct tty_struct *tty, struct file *file,
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unsigned int cmd, unsigned long arg);
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long (*compat_ioctl)(struct tty_struct *tty, struct file *file,
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unsigned int cmd, unsigned long arg);
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void (*set_termios)(struct tty_struct *tty, struct ktermios *old);
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__poll_t (*poll)(struct tty_struct *, struct file *,
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struct poll_table_struct *);
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int (*hangup)(struct tty_struct *tty);
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/*
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* The following routines are called from below.
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*/
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void (*receive_buf)(struct tty_struct *, const unsigned char *cp,
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char *fp, int count);
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void (*write_wakeup)(struct tty_struct *);
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void (*dcd_change)(struct tty_struct *, unsigned int);
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int (*receive_buf2)(struct tty_struct *, const unsigned char *cp,
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char *fp, int count);
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struct module *owner;
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int refcount;
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};
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struct tty_ldisc {
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struct tty_ldisc_ops *ops;
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struct tty_struct *tty;
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};
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#define TTY_LDISC_MAGIC 0x5403
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#define LDISC_FLAG_DEFINED 0x00000001
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#define MODULE_ALIAS_LDISC(ldisc) \
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MODULE_ALIAS("tty-ldisc-" __stringify(ldisc))
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#endif /* _LINUX_TTY_LDISC_H */
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