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kernel-aes67/include/linux/tty.h
Alan Cox 33f0f88f1c [PATCH] TTY layer buffering revamp 
The API and code have been through various bits of initial review by
serial driver people but they definitely need to live somewhere for a
while so the unconverted drivers can get knocked into shape, existing
drivers that have been updated can be better tuned and bugs whacked out.

This replaces the tty flip buffers with kmalloc objects in rings. In the
normal situation for an IRQ driven serial port at typical speeds the
behaviour is pretty much the same, two buffers end up allocated and the
kernel cycles between them as before.

When there are delays or at high speed we now behave far better as the
buffer pool can grow a bit rather than lose characters. This also means
that we can operate at higher speeds reliably.

For drivers that receive characters in blocks (DMA based, USB and
especially virtualisation) the layer allows a lot of driver specific
code that works around the tty layer with private secondary queues to be
removed. The IBM folks need this sort of layer, the smart serial port
people do, the virtualisers do (because a virtualised tty typically
operates at infinite speed rather than emulating 9600 baud).

Finally many drivers had invalid and unsafe attempts to avoid buffer
overflows by directly invoking tty methods extracted out of the innards
of work queue structs. These are no longer needed and all go away. That
fixes various random hangs with serial ports on overflow.

The other change in here is to optimise the receive_room path that is
used by some callers. It turns out that only one ldisc uses receive room
except asa constant and it updates it far far less than the value is
read. We thus make it a variable not a function call.

I expect the code to contain bugs due to the size alone but I'll be
watching and squashing them and feeding out new patches as it goes.

Because the buffers now dynamically expand you should only run out of
buffering when the kernel runs out of memory for real.  That means a lot of
the horrible hacks high performance drivers used to do just aren't needed any
more.

Description:

tty_insert_flip_char is an old API and continues to work as before, as does
tty_flip_buffer_push() [this is why many drivers dont need modification].  It
does now also return the number of chars inserted

There are also

tty_buffer_request_room(tty, len)

which asks for a buffer block of the length requested and returns the space
found.  This improves efficiency with hardware that knows how much to
transfer.

and tty_insert_flip_string_flags(tty, str, flags, len)

to insert a string of characters and flags

For a smart interface the usual code is

    len = tty_request_buffer_room(tty, amount_hardware_says);
    tty_insert_flip_string(tty, buffer_from_card, len);

More description!

At the moment tty buffers are attached directly to the tty.  This is causing a
lot of the problems related to tty layer locking, also problems at high speed
and also with bursty data (such as occurs in virtualised environments)

I'm working on ripping out the flip buffers and replacing them with a pool of
dynamically allocated buffers.  This allows both for old style "byte I/O"
devices and also helps virtualisation and smart devices where large blocks of
data suddenely materialise and need storing.

So far so good.  Lots of drivers reference tty->flip.*.  Several of them also
call directly and unsafely into function pointers it provides.  This will all
break.  Most drivers can use tty_insert_flip_char which can be kept as an API
but others need more.

At the moment I've added the following interfaces, if people think more will
be needed now is a good time to say

 int tty_buffer_request_room(tty, size)

Try and ensure at least size bytes are available, returns actual room (may be
zero).  At the moment it just uses the flipbuf space but that will change.
Repeated calls without characters being added are not cumulative.  (ie if you
call it with 1, 1, 1, and then 4 you'll have four characters of space.  The
other functions will also try and grow buffers in future but this will be a
more efficient way when you know block sizes.

 int tty_insert_flip_char(tty, ch, flag)

As before insert a character if there is room.  Now returns 1 for success, 0
for failure.

 int tty_insert_flip_string(tty, str, len)

Insert a block of non error characters.  Returns the number inserted.

 int tty_prepare_flip_string(tty, strptr, len)

Adjust the buffer to allow len characters to be added.  Returns a buffer
pointer in strptr and the length available.  This allows for hardware that
needs to use functions like insl or mencpy_fromio.

Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Paul Fulghum <paulkf@microgate.com>
Signed-off-by: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: John Hawkes <hawkes@sgi.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-10 08:01:59 -08:00

352 lines
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#ifndef _LINUX_TTY_H
#define _LINUX_TTY_H
/*
* 'tty.h' defines some structures used by tty_io.c and some defines.
*/
/*
* These constants are also useful for user-level apps (e.g., VC
* resizing).
*/
#define MIN_NR_CONSOLES 1 /* must be at least 1 */
#define MAX_NR_CONSOLES 63 /* serial lines start at 64 */
#define MAX_NR_USER_CONSOLES 63 /* must be root to allocate above this */
/* Note: the ioctl VT_GETSTATE does not work for
consoles 16 and higher (since it returns a short) */
#ifdef __KERNEL__
#include <linux/config.h>
#include <linux/fs.h>
#include <linux/major.h>
#include <linux/termios.h>
#include <linux/workqueue.h>
#include <linux/tty_driver.h>
#include <linux/tty_ldisc.h>
#include <linux/screen_info.h>
#include <asm/system.h>
/*
* (Note: the *_driver.minor_start values 1, 64, 128, 192 are
* hardcoded at present.)
*/
#define NR_PTYS CONFIG_LEGACY_PTY_COUNT /* Number of legacy ptys */
#define NR_UNIX98_PTY_DEFAULT 4096 /* Default maximum for Unix98 ptys */
#define NR_UNIX98_PTY_MAX (1 << MINORBITS) /* Absolute limit */
#define NR_LDISCS 16
/*
* This character is the same as _POSIX_VDISABLE: it cannot be used as
* a c_cc[] character, but indicates that a particular special character
* isn't in use (eg VINTR has no character etc)
*/
#define __DISABLED_CHAR '\0'
/*
* This is the flip buffer used for the tty driver. The buffer is
* located in the tty structure, and is used as a high speed interface
* between the tty driver and the tty line discipline.
*/
#define TTY_FLIPBUF_SIZE 512
struct tty_buffer {
struct tty_buffer *next;
char *char_buf_ptr;
unsigned char *flag_buf_ptr;
int used;
int size;
/* Data points here */
unsigned long data[0];
};
struct tty_bufhead {
struct work_struct work;
struct semaphore pty_sem;
struct tty_buffer *head; /* Queue head */
struct tty_buffer *tail; /* Active buffer */
struct tty_buffer *free; /* Free queue head */
};
/*
* The pty uses char_buf and flag_buf as a contiguous buffer
*/
#define PTY_BUF_SIZE 4*TTY_FLIPBUF_SIZE
/*
* When a break, frame error, or parity error happens, these codes are
* stuffed into the flags buffer.
*/
#define TTY_NORMAL 0
#define TTY_BREAK 1
#define TTY_FRAME 2
#define TTY_PARITY 3
#define TTY_OVERRUN 4
#define INTR_CHAR(tty) ((tty)->termios->c_cc[VINTR])
#define QUIT_CHAR(tty) ((tty)->termios->c_cc[VQUIT])
#define ERASE_CHAR(tty) ((tty)->termios->c_cc[VERASE])
#define KILL_CHAR(tty) ((tty)->termios->c_cc[VKILL])
#define EOF_CHAR(tty) ((tty)->termios->c_cc[VEOF])
#define TIME_CHAR(tty) ((tty)->termios->c_cc[VTIME])
#define MIN_CHAR(tty) ((tty)->termios->c_cc[VMIN])
#define SWTC_CHAR(tty) ((tty)->termios->c_cc[VSWTC])
#define START_CHAR(tty) ((tty)->termios->c_cc[VSTART])
#define STOP_CHAR(tty) ((tty)->termios->c_cc[VSTOP])
#define SUSP_CHAR(tty) ((tty)->termios->c_cc[VSUSP])
#define EOL_CHAR(tty) ((tty)->termios->c_cc[VEOL])
#define REPRINT_CHAR(tty) ((tty)->termios->c_cc[VREPRINT])
#define DISCARD_CHAR(tty) ((tty)->termios->c_cc[VDISCARD])
#define WERASE_CHAR(tty) ((tty)->termios->c_cc[VWERASE])
#define LNEXT_CHAR(tty) ((tty)->termios->c_cc[VLNEXT])
#define EOL2_CHAR(tty) ((tty)->termios->c_cc[VEOL2])
#define _I_FLAG(tty,f) ((tty)->termios->c_iflag & (f))
#define _O_FLAG(tty,f) ((tty)->termios->c_oflag & (f))
#define _C_FLAG(tty,f) ((tty)->termios->c_cflag & (f))
#define _L_FLAG(tty,f) ((tty)->termios->c_lflag & (f))
#define I_IGNBRK(tty) _I_FLAG((tty),IGNBRK)
#define I_BRKINT(tty) _I_FLAG((tty),BRKINT)
#define I_IGNPAR(tty) _I_FLAG((tty),IGNPAR)
#define I_PARMRK(tty) _I_FLAG((tty),PARMRK)
#define I_INPCK(tty) _I_FLAG((tty),INPCK)
#define I_ISTRIP(tty) _I_FLAG((tty),ISTRIP)
#define I_INLCR(tty) _I_FLAG((tty),INLCR)
#define I_IGNCR(tty) _I_FLAG((tty),IGNCR)
#define I_ICRNL(tty) _I_FLAG((tty),ICRNL)
#define I_IUCLC(tty) _I_FLAG((tty),IUCLC)
#define I_IXON(tty) _I_FLAG((tty),IXON)
#define I_IXANY(tty) _I_FLAG((tty),IXANY)
#define I_IXOFF(tty) _I_FLAG((tty),IXOFF)
#define I_IMAXBEL(tty) _I_FLAG((tty),IMAXBEL)
#define I_IUTF8(tty) _I_FLAG((tty),IUTF8)
#define O_OPOST(tty) _O_FLAG((tty),OPOST)
#define O_OLCUC(tty) _O_FLAG((tty),OLCUC)
#define O_ONLCR(tty) _O_FLAG((tty),ONLCR)
#define O_OCRNL(tty) _O_FLAG((tty),OCRNL)
#define O_ONOCR(tty) _O_FLAG((tty),ONOCR)
#define O_ONLRET(tty) _O_FLAG((tty),ONLRET)
#define O_OFILL(tty) _O_FLAG((tty),OFILL)
#define O_OFDEL(tty) _O_FLAG((tty),OFDEL)
#define O_NLDLY(tty) _O_FLAG((tty),NLDLY)
#define O_CRDLY(tty) _O_FLAG((tty),CRDLY)
#define O_TABDLY(tty) _O_FLAG((tty),TABDLY)
#define O_BSDLY(tty) _O_FLAG((tty),BSDLY)
#define O_VTDLY(tty) _O_FLAG((tty),VTDLY)
#define O_FFDLY(tty) _O_FLAG((tty),FFDLY)
#define C_BAUD(tty) _C_FLAG((tty),CBAUD)
#define C_CSIZE(tty) _C_FLAG((tty),CSIZE)
#define C_CSTOPB(tty) _C_FLAG((tty),CSTOPB)
#define C_CREAD(tty) _C_FLAG((tty),CREAD)
#define C_PARENB(tty) _C_FLAG((tty),PARENB)
#define C_PARODD(tty) _C_FLAG((tty),PARODD)
#define C_HUPCL(tty) _C_FLAG((tty),HUPCL)
#define C_CLOCAL(tty) _C_FLAG((tty),CLOCAL)
#define C_CIBAUD(tty) _C_FLAG((tty),CIBAUD)
#define C_CRTSCTS(tty) _C_FLAG((tty),CRTSCTS)
#define L_ISIG(tty) _L_FLAG((tty),ISIG)
#define L_ICANON(tty) _L_FLAG((tty),ICANON)
#define L_XCASE(tty) _L_FLAG((tty),XCASE)
#define L_ECHO(tty) _L_FLAG((tty),ECHO)
#define L_ECHOE(tty) _L_FLAG((tty),ECHOE)
#define L_ECHOK(tty) _L_FLAG((tty),ECHOK)
#define L_ECHONL(tty) _L_FLAG((tty),ECHONL)
#define L_NOFLSH(tty) _L_FLAG((tty),NOFLSH)
#define L_TOSTOP(tty) _L_FLAG((tty),TOSTOP)
#define L_ECHOCTL(tty) _L_FLAG((tty),ECHOCTL)
#define L_ECHOPRT(tty) _L_FLAG((tty),ECHOPRT)
#define L_ECHOKE(tty) _L_FLAG((tty),ECHOKE)
#define L_FLUSHO(tty) _L_FLAG((tty),FLUSHO)
#define L_PENDIN(tty) _L_FLAG((tty),PENDIN)
#define L_IEXTEN(tty) _L_FLAG((tty),IEXTEN)
struct device;
/*
* Where all of the state associated with a tty is kept while the tty
* is open. Since the termios state should be kept even if the tty
* has been closed --- for things like the baud rate, etc --- it is
* not stored here, but rather a pointer to the real state is stored
* here. Possible the winsize structure should have the same
* treatment, but (1) the default 80x24 is usually right and (2) it's
* most often used by a windowing system, which will set the correct
* size each time the window is created or resized anyway.
* - TYT, 9/14/92
*/
struct tty_struct {
int magic;
struct tty_driver *driver;
int index;
struct tty_ldisc ldisc;
struct semaphore termios_sem;
struct termios *termios, *termios_locked;
char name[64];
int pgrp;
int session;
unsigned long flags;
int count;
struct winsize winsize;
unsigned char stopped:1, hw_stopped:1, flow_stopped:1, packet:1;
unsigned char low_latency:1, warned:1;
unsigned char ctrl_status;
unsigned int receive_room; /* Bytes free for queue */
struct tty_struct *link;
struct fasync_struct *fasync;
struct tty_bufhead buf;
int max_flip_cnt;
int alt_speed; /* For magic substitution of 38400 bps */
wait_queue_head_t write_wait;
wait_queue_head_t read_wait;
struct work_struct hangup_work;
void *disc_data;
void *driver_data;
struct list_head tty_files;
#define N_TTY_BUF_SIZE 4096
/*
* The following is data for the N_TTY line discipline. For
* historical reasons, this is included in the tty structure.
*/
unsigned int column;
unsigned char lnext:1, erasing:1, raw:1, real_raw:1, icanon:1;
unsigned char closing:1;
unsigned short minimum_to_wake;
unsigned long overrun_time;
int num_overrun;
unsigned long process_char_map[256/(8*sizeof(unsigned long))];
char *read_buf;
int read_head;
int read_tail;
int read_cnt;
unsigned long read_flags[N_TTY_BUF_SIZE/(8*sizeof(unsigned long))];
int canon_data;
unsigned long canon_head;
unsigned int canon_column;
struct semaphore atomic_read;
struct semaphore atomic_write;
unsigned char *write_buf;
int write_cnt;
spinlock_t read_lock;
/* If the tty has a pending do_SAK, queue it here - akpm */
struct work_struct SAK_work;
};
/* tty magic number */
#define TTY_MAGIC 0x5401
/*
* These bits are used in the flags field of the tty structure.
*
* So that interrupts won't be able to mess up the queues,
* copy_to_cooked must be atomic with respect to itself, as must
* tty->write. Thus, you must use the inline functions set_bit() and
* clear_bit() to make things atomic.
*/
#define TTY_THROTTLED 0 /* Call unthrottle() at threshold min */
#define TTY_IO_ERROR 1 /* Canse an I/O error (may be no ldisc too) */
#define TTY_OTHER_CLOSED 2 /* Other side (if any) has closed */
#define TTY_EXCLUSIVE 3 /* Exclusive open mode */
#define TTY_DEBUG 4 /* Debugging */
#define TTY_DO_WRITE_WAKEUP 5 /* Call write_wakeup after queuing new */
#define TTY_PUSH 6 /* n_tty private */
#define TTY_CLOSING 7 /* ->close() in progress */
#define TTY_DONT_FLIP 8 /* Defer buffer flip */
#define TTY_LDISC 9 /* Line discipline attached */
#define TTY_HW_COOK_OUT 14 /* Hardware can do output cooking */
#define TTY_HW_COOK_IN 15 /* Hardware can do input cooking */
#define TTY_PTY_LOCK 16 /* pty private */
#define TTY_NO_WRITE_SPLIT 17 /* Preserve write boundaries to driver */
#define TTY_HUPPED 18 /* Post driver->hangup() */
#define TTY_WRITE_FLUSH(tty) tty_write_flush((tty))
extern void tty_write_flush(struct tty_struct *);
extern struct termios tty_std_termios;
extern int fg_console, last_console, want_console;
extern int kmsg_redirect;
extern void console_init(void);
extern int vcs_init(void);
extern int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
const char *routine);
extern char *tty_name(struct tty_struct *tty, char *buf);
extern void tty_wait_until_sent(struct tty_struct * tty, long timeout);
extern int tty_check_change(struct tty_struct * tty);
extern void stop_tty(struct tty_struct * tty);
extern void start_tty(struct tty_struct * tty);
extern int tty_register_ldisc(int disc, struct tty_ldisc *new_ldisc);
extern int tty_unregister_ldisc(int disc);
extern int tty_register_driver(struct tty_driver *driver);
extern int tty_unregister_driver(struct tty_driver *driver);
extern void tty_register_device(struct tty_driver *driver, unsigned index, struct device *dev);
extern void tty_unregister_device(struct tty_driver *driver, unsigned index);
extern int tty_read_raw_data(struct tty_struct *tty, unsigned char *bufp,
int buflen);
extern void tty_write_message(struct tty_struct *tty, char *msg);
extern int is_orphaned_pgrp(int pgrp);
extern int is_ignored(int sig);
extern int tty_signal(int sig, struct tty_struct *tty);
extern void tty_hangup(struct tty_struct * tty);
extern void tty_vhangup(struct tty_struct * tty);
extern void tty_unhangup(struct file *filp);
extern int tty_hung_up_p(struct file * filp);
extern void do_SAK(struct tty_struct *tty);
extern void disassociate_ctty(int priv);
extern void tty_flip_buffer_push(struct tty_struct *tty);
extern int tty_get_baud_rate(struct tty_struct *tty);
extern int tty_termios_baud_rate(struct termios *termios);
extern struct tty_ldisc *tty_ldisc_ref(struct tty_struct *);
extern void tty_ldisc_deref(struct tty_ldisc *);
extern struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *);
extern struct tty_ldisc *tty_ldisc_get(int);
extern void tty_ldisc_put(int);
extern void tty_wakeup(struct tty_struct *tty);
extern void tty_ldisc_flush(struct tty_struct *tty);
struct semaphore;
extern struct semaphore tty_sem;
/* n_tty.c */
extern struct tty_ldisc tty_ldisc_N_TTY;
/* tty_ioctl.c */
extern int n_tty_ioctl(struct tty_struct * tty, struct file * file,
unsigned int cmd, unsigned long arg);
/* serial.c */
extern void serial_console_init(void);
/* pcxx.c */
extern int pcxe_open(struct tty_struct *tty, struct file *filp);
/* printk.c */
extern void console_print(const char *);
/* vt.c */
extern int vt_ioctl(struct tty_struct *tty, struct file * file,
unsigned int cmd, unsigned long arg);
static inline dev_t tty_devnum(struct tty_struct *tty)
{
return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
}
#endif /* __KERNEL__ */
#endif
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