TTYDEV

Structure for a tty device

Synopsis:

typedef struct ttydev_entry {
    iofunc_attr_t       attr;
    iofunc_mount_t      mount;
    TTYPOWER            power;
    TTYWAIT                     *waiting_read;
    TTYWAIT                     *waiting_write;
    TTYWAIT                     *waiting_drain;
    TTYWAIT                     *waiting_devctl;
    int                         c_cflag;
    int                         c_iflag;
    int                         c_lflag;
    int                         c_oflag;
    volatile unsigned           flags;
    volatile unsigned           xflags;
    volatile unsigned           eflags;
    volatile unsigned           lflags;
    unsigned int        bcnt;
    unsigned int        fwdcnt;
    struct ttydev_entry         *timer;
    int                         timeout;
    int                         timeout_reset;
    union {
        uint64_t        tmrs;
        struct {
            char            drn_tmr;
            char            tx_tmr;
            char            brk_tmr;
            char            dtr_tmr;
            char            spare_tmr;
            char            rsvd1;
            char            rsvd2;
            char            rsvd3;
        }   s;
    }       un;
    pid_t                       brkpgrp;
    pid_t                       huppid;
    cc_t                        c_cc[NCCS];
    unsigned char               fifo;
    unsigned char               fwd;
    unsigned char               prefix_cnt;
    unsigned char               oband_data;
    int                         highwater;
    int                         baud;
    struct winsize              winsize;
    TTYBUF                      obuf;
    TTYBUF                      ibuf;
    TTYBUF                      cbuf;
    iofunc_notify_t             notify[3];
    struct ttydev_entry         *extra;
    TTYWAIT                     *waiting_open;  
    int             linkid;
    void                        *reserved2;    
    int                         (*io_devctlext)(resmgr_context_t *ctp,
                                                io_devctl_t *msg,
                                                iofunc_ocb_t *ocb);
    char                        name[TTY_NAME_MAX];
    } TTYDEV;

Description:

A character driver shares the TTYDEV structure with the io-char library.

This structure is used to handle devices shared between the driver and io-char.

The members include:

attr

A resource manager attribute.

mount

Related to resource manager information.

power

A power-management attribute.

waiting_read

The queue to store blocking clients waiting to read.

waiting_write

The queue to store blocking clients waiting to write.

waiting_drain

The queue to store blocking clients waiting to drain.

c_cflag

POSIX termios flag describing the hardware control of the terminal.

c_iflag

POSIX termios flag describing the basic terminal input control.

c_lflag

POSIX termios flag used to control various terminal functions.

c_oflag

POSIX termios flag describing the basic terminal output control.

flags

The following flags are currently defined:

• OHW_PAGED — the output hardware flow control (set by io-char and used by the driver).
• IHW_PAGED — input hardware flow control is asserted; the device's highwater mark has been reached, and the device doesn't want to receive any more data. This flag also asserts the RTS line.
• OSW_PAGED — output software flow control is asserted; the device should not transmit any data (set by io-char and used by the driver).
• ISW_PAGED — input software flow control is asserted; the device's highwater mark has been reached, and the device doesn't want to receive any more data. This flag also transmits VSTOP.
• EDIT_INSERT — for edit mode. Insert or overstrike typing mode.
• EDIT_PREFIX — for edit mode. Look for edit keys which begin with a fixed prefix, e.g. ESC [ ansi" used with POSIX c_cc[VPREFIX].
• OBAND_DATA — indicates that out-of-band data is available.
• LOSES_TX_INTR — tells the character device library (io-char) that the device sometimes fails to generate TX interrupts. With this knowledge of the hardware's shortcomings, the io-char library will take extra precautions when transmitting data, by using an internal countdown timer to keep track of the time between TX interrupts. If the timer expires before the next TX interrupt comes in, the io-char library assumes the hardware failed to generate the interrupt and attempts to transmit more data by calling tto(). If there's no more data to be transmitted, the countdown timer isn't reloaded.
• TIMER_ACTIVE — used by io-char.
• TIMER_KEEP — used by io-char.
• NOTTY — used by PTYs.
• NL_INSERT — used to notify application if a \n was changed to a \r.
• ISAPTY — used by PTYs.
• PTY_MASTER_ONLY — used by PTYs.
• LITERAL — used by io-char.
• FIRST_TIME_ALONE — used by io-char.

Flags indicate which event occurred. Then the driver sends the event to io-char.

The following events are currently defined:

• EVENT_QUEUED — there is an event queued.
• EVENT_SIGINT — an interrupt character event was received, or a break event was received.
• EVENT_SIGHUP — POSIX job control, TTI_HANGUP.
• EVENT_SIGBRK — POSIX job control for SIGBRK sends SIGINT. This event is called by TTI_BREAK, so the driver probably doesn't need to do this.
• EVENT_TTO — used to call into the tto() at thread time to transmit data. Interrupt handler can return this event rather than calling tto() directly.
• EVENT_READ — used by io-char.
• EVENT_WRITE — called by the driver. Unblock an application waiting to write when the output buffer has room to take characters.
• EVENT_DRAIN — called by the driver. The output buffer has drained (unblock someone waiting on the device to drain).
• EVENT_TIMEOUT — used by io-char.
• EVENT_NOTIFY_INPUT — input notification (used by io-char). See the notify entry in TTYDEV.
• EVENT_NOTIFY_OUTPUT — output notification (used by io-char. See the notify entry in TTYDEV.
• EVENT_NOTIFY_OBAND — driver notifies io-char if out-of-band data is available.
• EVENT_CARRIER — generated by TTI_CARRIER.
• EVENT_SIGQUIT — job control, generated by TTI_QUIT to notify that a QUIT character has been received.
• EVENT_SIGSUP — job control, generated by TTI_SUSP to notify that a SUSP character has been received.

xflags

OSW_PAGED_OVERRIDE — override OSW_PAGED to allow transmission of controlled characters when in a software flow-control suspend state. This flag is set by io-char, and is used and cleared by the driver.

eflags

Event flag, extension to the event in the flags variable.

lflags

Logging flag.

bcnt

Internal to io-char and used to determine the number of bytes needed to notify a read client.

fwdcnt

Internal to io-char and used to determine the number of fwd counts.

timer

Used by io-char.

timeout

Used by io-char.

timeout_reset

Used by io-char.

tmrs

One of the below available timers for io-char to use.

drn_tmr

Drain timer.

tx_tmr

Loses tx interrupt timer. Enabled by LOSES_TX_INTR. The timer causes tto() to be called to work around some parts that lose transmit interrupts.

brk_tmr

Break timer. Used only by io-char sending break; calls tto(TTO_CTRL, dtrchg).

dtr_tmr

dtr line timer. Used by io-char to set dtr line i.e. generate SIGHUP calls tto(TTO_CTRL, dtrchg).

spare_tmr

Spare timer for driver use ONLY .

dsr_tmr

For device-side driver where DSR is an output.

dcd_tmr

For device-side driver where DCD is an output.

rsvd3

Reserved for more timers to be added.

brkpgrp

Used by io-char.

huppid

Used by io-char.

c_cc

POSIX special control-characters.

fifo

Used only by the driver.

fwd

Forward character used by io-char. It's used with fwdcnt to implement forward, described in readcond(). For more information, see the QNX Neutrino Library Reference .

prefix_cnt

For io-char only.

oband_data

Out-of-band data set by the driver in <intr.c>. The application gets it from io-char via a devctl().

highwater

Set by the driver and used by io-char to determine when to invoke flow control. (Make sure this value is LESS than the input buffer size).

baud

The device's baud rate.

winsize

Used only by io-char.

obuf

The output buffer.

ibuf

The input buffer.

cbuf

The canonical buffer.

notify

An array of three iofunc_notify_t structures that represent (in order), the input, output, and out-of-band notification list:

• notify[0] — notify for input used by io-char.
• notify[1] — notify for output to the driver, tto.c.
• notify[2] — notify for data that out-of-band to the driver, intr.c

For information about this structure, see the entry for iofunc_notify() in the QNX Neutrino Library Reference.

extra

Used for PTYs.

waiting_open

The queue to store blocking clients waiting to open.

linkid

The ID returned from resmgr_attach().

reserved2

Reserved for use by io-char.

io_devctlext

Custom devctl command.

name

The device's name e.g. /dev/ser1.

Classification:

QNX Neutrino

See also:

TTYCTRL