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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_TTY_DRIVER_H
#define _LINUX_TTY_DRIVER_H
/*
* This structure defines the interface between the low-level tty
* driver 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.
*
* struct tty_struct * (*lookup)(struct tty_driver *self, struct file *, int idx)
*
* Return the tty device corresponding to idx, NULL if there is not
* one currently in use and an ERR_PTR value on error. Called under
* tty_mutex (for now!)
*
* Optional method. Default behaviour is to use the ttys array
*
* int (*install)(struct tty_driver *self, struct tty_struct *tty)
*
* Install a new tty into the tty driver internal tables. Used in
* conjunction with lookup and remove methods.
*
* Optional method. Default behaviour is to use the ttys array
*
* void (*remove)(struct tty_driver *self, struct tty_struct *tty)
*
* Remove a closed tty from the tty driver internal tables. Used in
* conjunction with lookup and remove methods.
*
* Optional method. Default behaviour is to use the ttys array
*
* int (*open)(struct tty_struct * tty, struct file * filp);
*
* This routine is called when a particular tty device is opened.
* This routine is mandatory; if this routine is not filled in,
* the attempted open will fail with ENODEV.
*
* Required method. Called with tty lock held.
*
* void (*close)(struct tty_struct * tty, struct file * filp);
*
* This routine is called when a particular tty device is closed.
* Note: called even if the corresponding open() failed.
*
* Required method. Called with tty lock held.
*
* void (*shutdown)(struct tty_struct * tty);
*
* This routine is called under the tty lock when a particular tty device
* is closed for the last time. It executes before the tty resources
* are freed so may execute while another function holds a tty kref.
*
* void (*cleanup)(struct tty_struct * tty);
*
* This routine is called asynchronously when a particular tty device
* is closed for the last time freeing up the resources. This is
* actually the second part of shutdown for routines that might sleep.
*
*
* int (*write)(struct tty_struct * tty,
* const unsigned char *buf, int count);
*
* This routine is called by the kernel to write a series of
* characters to the tty device. The characters may come from
* user space or kernel space. This routine will return the
* number of characters actually accepted for writing.
*
* Optional: Required for writable devices.
*
* int (*put_char)(struct tty_struct *tty, unsigned char ch);
*
* This routine is called by the kernel to write a single
* character to the tty device. If the kernel uses this routine,
* it must call the flush_chars() routine (if defined) when it is
* done stuffing characters into the driver. If there is no room
* in the queue, the character is ignored.
*
* Optional: Kernel will use the write method if not provided.
*
* Note: Do not call this function directly, call tty_put_char
*
* void (*flush_chars)(struct tty_struct *tty);
*
* This routine is called by the kernel after it has written a
* series of characters to the tty device using put_char().
*
* Optional:
*
* Note: Do not call this function directly, call tty_driver_flush_chars
*
* unsigned int (*write_room)(struct tty_struct *tty);
*
* This routine returns the numbers of characters the tty driver
* will accept for queuing to be written. This number is subject
* to change as output buffers get emptied, or if the output flow
* control is acted.
*
* Required if write method is provided else not needed.
*
* Note: Do not call this function directly, call tty_write_room
*
* int (*ioctl)(struct tty_struct *tty, unsigned int cmd, unsigned long arg);
*
* This routine allows the tty driver to implement
* device-specific ioctls. If the ioctl number passed in cmd
* is not recognized by the driver, it should return ENOIOCTLCMD.
*
* Optional
*
* long (*compat_ioctl)(struct tty_struct *tty,,
* unsigned int cmd, unsigned long arg);
*
* implement ioctl processing for 32 bit process on 64 bit system
*
* Optional
*
* void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
*
* This routine allows the tty driver to be notified when
* device's termios settings have changed.
*
* Optional: Called under the termios lock
*
*
* void (*set_ldisc)(struct tty_struct *tty);
*
* This routine allows the tty driver to be notified when the
* device's termios settings have changed.
*
* Optional: Called under BKL (currently)
*
* void (*throttle)(struct tty_struct * tty);
*
* This routine notifies the tty driver that input buffers for
* the line discipline are close to full, and it should somehow
* signal that no more characters should be sent to the tty.
*
* Optional: Always invoke via tty_throttle_safe(), called under the
* termios lock.
*
* void (*unthrottle)(struct tty_struct * tty);
*
* This routine notifies the tty drivers that it should signals
* that characters can now be sent to the tty without fear of
* overrunning the input buffers of the line disciplines.
*
* Optional: Always invoke via tty_unthrottle(), called under the
* termios lock.
*
* void (*stop)(struct tty_struct *tty);
*
* This routine notifies the tty driver that it should stop
* outputting characters to the tty device.
*
* Called with ->flow.lock held. Serialized with start() method.
*
* Optional:
*
* Note: Call stop_tty not this method.
*
* void (*start)(struct tty_struct *tty);
*
* This routine notifies the tty driver that it resume sending
* characters to the tty device.
*
* Called with ->flow.lock held. Serialized with stop() method.
*
* Optional:
*
* Note: Call start_tty not this method.
*
* void (*hangup)(struct tty_struct *tty);
*
* This routine notifies the tty driver that it should hang up the
* tty device.
*
* Optional:
*
* Called with tty lock held.
*
* int (*break_ctl)(struct tty_struct *tty, int state);
*
* This optional routine requests the tty driver to turn on or
* off BREAK status on the RS-232 port. If state is -1,
* then the BREAK status should be turned on; if state is 0, then
* BREAK should be turned off.
*
* If this routine is implemented, the high-level tty driver will
* handle the following ioctls: TCSBRK, TCSBRKP, TIOCSBRK,
* TIOCCBRK.
*
* If the driver sets TTY_DRIVER_HARDWARE_BREAK then the interface
* will also be called with actual times and the hardware is expected
* to do the delay work itself. 0 and -1 are still used for on/off.
*
* Optional: Required for TCSBRK/BRKP/etc handling.
*
* void (*wait_until_sent)(struct tty_struct *tty, int timeout);
*
* This routine waits until the device has written out all of the
* characters in its transmitter FIFO.
*
* Optional: If not provided the device is assumed to have no FIFO
*
* Note: Usually correct to call tty_wait_until_sent
*
* void (*send_xchar)(struct tty_struct *tty, char ch);
*
* This routine is used to send a high-priority XON/XOFF
* character to the device.
*
* Optional: If not provided then the write method is called under
* the atomic write lock to keep it serialized with the ldisc.
*
* int (*resize)(struct tty_struct *tty, struct winsize *ws)
*
* Called when a termios request is issued which changes the
* requested terminal geometry.
*
* Optional: the default action is to update the termios structure
* without error. This is usually the correct behaviour. Drivers should
* not force errors here if they are not resizable objects (eg a serial
* line). See tty_do_resize() if you need to wrap the standard method
* in your own logic - the usual case.
*
* int (*get_icount)(struct tty_struct *tty, struct serial_icounter *icount);
*
* Called when the device receives a TIOCGICOUNT ioctl. Passed a kernel
* structure to complete. This method is optional and will only be called
* if provided (otherwise ENOTTY will be returned).
*/
#include <linux/export.h>
#include <linux/fs.h>
#include <linux/kref.h>
#include <linux/list.h>
#include <linux/cdev.h>
#include <linux/termios.h>
#include <linux/seq_file.h>
struct tty_struct;
struct tty_driver;
struct serial_icounter_struct;
struct serial_struct;
struct tty_operations {
struct tty_struct * (*lookup)(struct tty_driver *driver,
struct file *filp, int idx);
int (*install)(struct tty_driver *driver, struct tty_struct *tty);
void (*remove)(struct tty_driver *driver, struct tty_struct *tty);
int (*open)(struct tty_struct * tty, struct file * filp);
void (*close)(struct tty_struct * tty, struct file * filp);
void (*shutdown)(struct tty_struct *tty);
void (*cleanup)(struct tty_struct *tty);
int (*write)(struct tty_struct * tty,
const unsigned char *buf, int count);
int (*put_char)(struct tty_struct *tty, unsigned char ch);
void (*flush_chars)(struct tty_struct *tty);
unsigned int (*write_room)(struct tty_struct *tty);
unsigned int (*chars_in_buffer)(struct tty_struct *tty);
int (*ioctl)(struct tty_struct *tty,
unsigned int cmd, unsigned long arg);
long (*compat_ioctl)(struct tty_struct *tty,
unsigned int cmd, unsigned long arg);
void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
void (*throttle)(struct tty_struct * tty);
void (*unthrottle)(struct tty_struct * tty);
void (*stop)(struct tty_struct *tty);
void (*start)(struct tty_struct *tty);
void (*hangup)(struct tty_struct *tty);
int (*break_ctl)(struct tty_struct *tty, int state);
void (*flush_buffer)(struct tty_struct *tty);
void (*set_ldisc)(struct tty_struct *tty);
void (*wait_until_sent)(struct tty_struct *tty, int timeout);
void (*send_xchar)(struct tty_struct *tty, char ch);
int (*tiocmget)(struct tty_struct *tty);
int (*tiocmset)(struct tty_struct *tty,
unsigned int set, unsigned int clear);
int (*resize)(struct tty_struct *tty, struct winsize *ws);
int (*get_icount)(struct tty_struct *tty,
struct serial_icounter_struct *icount);
int (*get_serial)(struct tty_struct *tty, struct serial_struct *p);
int (*set_serial)(struct tty_struct *tty, struct serial_struct *p);
void (*show_fdinfo)(struct tty_struct *tty, struct seq_file *m);
#ifdef CONFIG_CONSOLE_POLL
int (*poll_init)(struct tty_driver *driver, int line, char *options);
int (*poll_get_char)(struct tty_driver *driver, int line);
void (*poll_put_char)(struct tty_driver *driver, int line, char ch);
#endif
int (*proc_show)(struct seq_file *, void *);
} __randomize_layout;
struct tty_driver {
int magic; /* magic number for this structure */
struct kref kref; /* Reference management */
struct cdev **cdevs;
struct module *owner;
const char *driver_name;
const char *name;
int name_base; /* offset of printed name */
int major; /* major device number */
int minor_start; /* start of minor device number */
unsigned int num; /* number of devices allocated */
short type; /* type of tty driver */
short subtype; /* subtype of tty driver */
struct ktermios init_termios; /* Initial termios */
unsigned long flags; /* tty driver flags */
struct proc_dir_entry *proc_entry; /* /proc fs entry */
struct tty_driver *other; /* only used for the PTY driver */
/*
* Pointer to the tty data structures
*/
struct tty_struct **ttys;
struct tty_port **ports;
struct ktermios **termios;
void *driver_state;
/*
* Driver methods
*/
const struct tty_operations *ops;
struct list_head tty_drivers;
} __randomize_layout;
extern struct list_head tty_drivers;
extern struct tty_driver *__tty_alloc_driver(unsigned int lines,
struct module *owner, unsigned long flags);
extern struct tty_driver *tty_find_polling_driver(char *name, int *line);
extern void tty_driver_kref_put(struct tty_driver *driver);
/* Use TTY_DRIVER_* flags below */
#define tty_alloc_driver(lines, flags) \
__tty_alloc_driver(lines, THIS_MODULE, flags)
static inline struct tty_driver *tty_driver_kref_get(struct tty_driver *d)
{
kref_get(&d->kref);
return d;
}
static inline void tty_set_operations(struct tty_driver *driver,
const struct tty_operations *op)
{
driver->ops = op;
}
/* tty driver magic number */
#define TTY_DRIVER_MAGIC 0x5402
/*
* tty driver flags
*
* TTY_DRIVER_RESET_TERMIOS --- requests the tty layer to reset the
* termios setting when the last process has closed the device.
* Used for PTY's, in particular.
*
* TTY_DRIVER_REAL_RAW --- if set, indicates that the driver will
* guarantee never not to set any special character handling
* flags if ((IGNBRK || (!BRKINT && !PARMRK)) && (IGNPAR ||
* !INPCK)). That is, if there is no reason for the driver to
* send notifications of parity and break characters up to the
* line driver, it won't do so. This allows the line driver to
* optimize for this case if this flag is set. (Note that there
* is also a promise, if the above case is true, not to signal
* overruns, either.)
*
* TTY_DRIVER_DYNAMIC_DEV --- if set, the individual tty devices need
* to be registered with a call to tty_register_device() when the
* device is found in the system and unregistered with a call to
* tty_unregister_device() so the devices will be show up
* properly in sysfs. If not set, driver->num entries will be
* created by the tty core in sysfs when tty_register_driver() is
* called. This is to be used by drivers that have tty devices
* that can appear and disappear while the main tty driver is
* registered with the tty core.
*
* TTY_DRIVER_DEVPTS_MEM -- don't use the standard arrays, instead
* use dynamic memory keyed through the devpts filesystem. This
* is only applicable to the pty driver.
*
* TTY_DRIVER_HARDWARE_BREAK -- hardware handles break signals. Pass
* the requested timeout to the caller instead of using a simple
* on/off interface.
*
* TTY_DRIVER_DYNAMIC_ALLOC -- do not allocate structures which are
* needed per line for this driver as it would waste memory.
* The driver will take care.
*
* TTY_DRIVER_UNNUMBERED_NODE -- do not create numbered /dev nodes. In
* other words create /dev/ttyprintk and not /dev/ttyprintk0.
* Applicable only when a driver for a single tty device is
* being allocated.
*/
#define TTY_DRIVER_INSTALLED 0x0001
#define TTY_DRIVER_RESET_TERMIOS 0x0002
#define TTY_DRIVER_REAL_RAW 0x0004
#define TTY_DRIVER_DYNAMIC_DEV 0x0008
#define TTY_DRIVER_DEVPTS_MEM 0x0010
#define TTY_DRIVER_HARDWARE_BREAK 0x0020
#define TTY_DRIVER_DYNAMIC_ALLOC 0x0040
#define TTY_DRIVER_UNNUMBERED_NODE 0x0080
/* tty driver types */
#define TTY_DRIVER_TYPE_SYSTEM 0x0001
#define TTY_DRIVER_TYPE_CONSOLE 0x0002
#define TTY_DRIVER_TYPE_SERIAL 0x0003
#define TTY_DRIVER_TYPE_PTY 0x0004
#define TTY_DRIVER_TYPE_SCC 0x0005 /* scc driver */
#define TTY_DRIVER_TYPE_SYSCONS 0x0006
/* system subtypes (magic, used by tty_io.c) */
#define SYSTEM_TYPE_TTY 0x0001
#define SYSTEM_TYPE_CONSOLE 0x0002
#define SYSTEM_TYPE_SYSCONS 0x0003
#define SYSTEM_TYPE_SYSPTMX 0x0004
/* pty subtypes (magic, used by tty_io.c) */
#define PTY_TYPE_MASTER 0x0001
#define PTY_TYPE_SLAVE 0x0002
/* serial subtype definitions */
#define SERIAL_TYPE_NORMAL 1
int tty_register_driver(struct tty_driver *driver);
void tty_unregister_driver(struct tty_driver *driver);
struct device *tty_register_device(struct tty_driver *driver, unsigned index,
struct device *dev);
struct device *tty_register_device_attr(struct tty_driver *driver,
unsigned index, struct device *device, void *drvdata,
const struct attribute_group **attr_grp);
void tty_unregister_device(struct tty_driver *driver, unsigned index);
#ifdef CONFIG_PROC_FS
void proc_tty_register_driver(struct tty_driver *);
void proc_tty_unregister_driver(struct tty_driver *);
#else
static inline void proc_tty_register_driver(struct tty_driver *d) {}
static inline void proc_tty_unregister_driver(struct tty_driver *d) {}
#endif
#endif /* #ifdef _LINUX_TTY_DRIVER_H */
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