tty_driver.h

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#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, 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.
 *     
 * void (*close)(struct tty_struct * tty, struct file * filp);
 *
 *  This routine is called when a particular tty device is closed.
 *
 *  Required method.
 *
 * 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
 * 
 * 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(), 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.  
 *
 *  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.
 *
 *  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:
 *
 * 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.
 *
 * void (*set_termiox)(struct tty_struct *tty, struct termiox *new);
 *
 *  Called when the device receives a termiox based ioctl. Passes down
 *  the requested data from user space. This method will not be invoked
 *  unless the tty also has a valid tty->termiox pointer.
 *
 *  Optional: Called under the termios lock
 *
 * 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 EINVAL will be returned).
 */

#include <linux/export.h>
#include <linux/fs.h>
#include <linux/list.h>
#include <linux/cdev.h>
#include <linux/termios.h>

struct tty_struct;
struct tty_driver;
struct serial_icounter_struct;

struct tty_operations {
    struct tty_struct * (*lookup)(struct tty_driver *driver,
            struct inode *inode, 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);
    int  (*write_room)(struct tty_struct *tty);
    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 (*set_termiox)(struct tty_struct *tty, struct termiox *tnew);
    int (*get_icount)(struct tty_struct *tty,
                struct serial_icounter_struct *icount);
#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
    const struct file_operations *proc_fops;
};

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;
};

extern struct list_head tty_drivers;

extern struct tty_driver *__tty_alloc_driver(unsigned int lines,
        struct module *owner, unsigned long flags);
extern void put_tty_driver(struct tty_driver *driver);
extern void tty_set_operations(struct tty_driver *driver,
            const struct tty_operations *op);
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)

/*
 * DEPRECATED Do not use this in new code, use tty_alloc_driver instead.
 * (And change the return value checks.)
 */
static inline struct tty_driver *alloc_tty_driver(unsigned int lines)
{
    struct tty_driver *ret = tty_alloc_driver(lines, 0);
    if (IS_ERR(ret))
        return NULL;
    return ret;
}

static inline struct tty_driver *tty_driver_kref_get(struct tty_driver *d)
{
    kref_get(&d->kref);
    return d;
}

/* 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

#endif /* #ifdef _LINUX_TTY_DRIVER_H */