cregit-Linux how code gets into the kernel

Release 4.7 include/linux/tty_ldisc.h

Directory: include/linux
#ifndef _LINUX_TTY_LDISC_H

#define _LINUX_TTY_LDISC_H

/*
 * 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, struct file * file,
 *               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.
 *
 * long (*compat_ioctl)(struct tty_struct * tty, struct file * file,
 *                      unsigned int cmd, unsigned long arg);
 *
 *      Process ioctl calls from 32-bit process on 64-bit system
 *
 * 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>


/*
 * the semaphore definition
 */

struct ld_semaphore {
	
long			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
};

extern 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)


extern int ldsem_down_read(struct ld_semaphore *sem, long timeout);
extern int ldsem_down_read_trylock(struct ld_semaphore *sem);
extern int ldsem_down_write(struct ld_semaphore *sem, long timeout);
extern int ldsem_down_write_trylock(struct ld_semaphore *sem);
extern void ldsem_up_read(struct ld_semaphore *sem);
extern void ldsem_up_write(struct ld_semaphore *sem);

#ifdef CONFIG_DEBUG_LOCK_ALLOC
extern int ldsem_down_read_nested(struct ld_semaphore *sem, int subclass,
				  long timeout);
extern 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 {
	
int	magic;
	
char	*name;
	
int	num;
	
int	flags;

	/*
         * The following routines are called from above.
         */
	
int	(*open)(struct tty_struct *);
	
void	(*close)(struct tty_struct *);
	
void	(*flush_buffer)(struct tty_struct *tty);
	
ssize_t	(*read)(struct tty_struct *tty, struct file *file,
			unsigned char __user *buf, size_t nr);
	
ssize_t	(*write)(struct tty_struct *tty, struct file *file,
			 const unsigned char *buf, size_t nr);
	
int	(*ioctl)(struct tty_struct *tty, struct file *file,
			 unsigned int cmd, unsigned long arg);
	
long	(*compat_ioctl)(struct tty_struct *tty, struct file *file,
				unsigned int cmd, unsigned long arg);
	
void	(*set_termios)(struct tty_struct *tty, struct ktermios *old);
	
unsigned int (*poll)(struct tty_struct *, struct file *,
			     struct poll_table_struct *);
	
int	(*hangup)(struct tty_struct *tty);

	/*
         * The following routines are called from below.
         */
	
void	(*receive_buf)(struct tty_struct *, const unsigned char *cp,
			       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,
				char *fp, int count);

	
struct  module *owner;

	
int refcount;
};


struct tty_ldisc {
	
struct tty_ldisc_ops *ops;
	
struct tty_struct *tty;
};


#define TTY_LDISC_MAGIC	0x5403


#define LDISC_FLAG_DEFINED	0x00000001


#define MODULE_ALIAS_LDISC(ldisc) \
	MODULE_ALIAS("tty-ldisc-" __stringify(ldisc))

#endif /* _LINUX_TTY_LDISC_H */

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pre-gitpre-git22242.45%733.33%
peter hurleypeter hurley21941.87%419.05%
alan coxalan cox275.16%314.29%
paul fulghumpaul fulghum254.78%14.76%
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Directory: include/linux
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