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WSDISPLAY(9)               Kernel Developer's Manual              WSDISPLAY(9)

NAME
     wsdisplay, wsdisplay_switchtoconsole, wsdisplay_cnattach,
     wsdisplaydevprint, wsemuldisplaydevprint -- wscons display support

SYNOPSIS
     #include <dev/wscons/wsconsio.h>
     #include <dev/wscons/wsdisplayvar.h>
     #include <dev/wscons/wsemulvar.h>
     #include <dev/wscons/wsemul_vt100var.h>

     void
     wsdisplay_switchtoconsole();

     void
     wsdisplay_cnattach(const struct wsscreen_descr *type, void *cookie,
         int ccol, int crow, long defattr);

     void
     wsemul_xxx_cnattach(const struct wsscreen_descr *type, void *cookie,
         int ccol, int crow, long defattr);

     int
     wsdisplaydevprint(void *aux, const char *pnp);

     int
     wsemuldisplaydevprint(void * aux, const char *pnp);

DESCRIPTION
     The wsdisplay module is a component of the wscons(9) framework to provide
     machine-independent display support.  Most of the support is provided by
     the wsdisplay(4) device driver, which must be a child of the hardware
     device driver.

     The wscons display interface is complicated by the fact that there are
     two different interfaces.  The first interface corresponds to the simple
     bit-mapped display which doesn't provide terminal-emulation and console
     facilities.  The second interface provides machine-independent terminal
     emulation for displays that can support glass-tty terminal emulations.
     These are character-oriented displays, with row and column numbers
     starting at zero in the upper left hand corner of the screen.  Display
     drivers which cannot emulate terminals use the first interface.  In most
     cases, the low-level hardware driver can use the rasops(9) interface to
     provide enough support to allow glass-tty terminal emulation.  If the
     display is not the console, terminal emulation does not make sense and
     the display operates using the bit-mapped interface.

     The wscons framework allows concurrent displays to be active.  It also
     provides support for multiple screens for each display and therefore
     allows a virtual terminal on each screen.  Multiple terminal emulations
     and fonts can be active at the same time allowing different emulations
     and fonts for each screen.

     Font manipulation facilities for the terminal emulation interface are
     available through the wsfont(9) module.

DATA TYPES
     Display drivers providing support for wscons displays will make use of
     the following data types:

     struct wsdisplay_accessops
              A structure used to specify the display access functions invoked
              by userland program which require direct device access, such as
              X11.  All displays must provide this structure and pass it to
              the wsdisplay(4) child device.  It has the following members:

                      int     (*ioctl)(void *v, void *vs, u_long cmd,
                                      void *data, int flag, struct lwp *l);
                      paddr_t (*mmap)(void *v, void *vs, off_t off, int prot);
                      int     (*alloc_screen)(void *,
                                      const struct wsscreen_descr *, void **,
                                      int *, int *, long *);
                      void    (*free_screen)(void *, void *);
                      int     (*show_screen)(void *, void *, int,
                                      void (*)(), void *);
                      int     (*load_font)(void *, void *,
                                      struct wsdisplay_font *);
                      void    (*pollc)(void *, int);
                      void    (*scroll)(void *, void *, int);

              The ioctl member defines the function to be called to perform
              display-specific ioctl calls.  The mmap member defines the
              function for mapping a part of the display device into user
              address space.  The alloc_screen member defines a function for
              allocating a new screen which can be used as a virtual terminal.
              The free_screen member defines a function for de-allocating a
              screen.  The show_screen member defines a function for mapping a
              screen onto the physical display.  This function is used for
              switching between screens.  The load_font member defines a
              function for loading a new font into the display.  The pollc
              member defines a function for polling the console.  The scroll
              member defines a function for scrolling the contents of the
              display.

              There is a void * cookie provided by the display driver
              associated with these functions, which is passed to them when
              they are invoked.

              The void *vs cookie, passed to ioctl() and mmap(), points to the
              virtual screen on which these operations were executed.

     struct wsdisplaydev_attach_args
              A structure used to attach the wsdisplay(4) child device for the
              simple bit-mapped interface.  It has the following members:

                      const struct wsdisplay_accessops *accessops;
                      void *accesscookie;
              If the full terminal-emulation interface is to be used, then
              struct wsemuldisplaydev_attach_args should be used instead.

     struct wsemuldisplaydev_attach_args
              A structure used to attach the wsdisplay(4) child device for the
              full terminal emulation interface.  It has the following
              members:

                      int console;
                      const struct wsscreen_list *scrdata;
                      const struct wsdisplay_accessops *accessops;
                      void *accesscookie;
              If the simple bit-mapped interface is to be used, then struct
              wsdisplaydev_attach_args should be used instead.

     struct wsdisplay_emulops
              A structure used to specify the display emulation functions.
              All displays intending to provide terminal emulation must
              provide this structure and pass it to the wsdisplay(4) child
              device.  It has the following members:

                      void    (*cursor)(void *c, int on, int row, int col);
                      int     (*mapchar)(void *, int, unsigned int *);
                      void    (*putchar)(void *c, int row, int col,
                                      u_int uc, long attr);
                      void    (*copycols)(void *c, int row, int srccol,
                                      int dstcol, int ncols);
                      void    (*erasecols)(void *c, int row, int startcol,
                                      int ncols, long);
                      void    (*copyrows)(void *c, int srcrow, int dstrow,
                                      int nrows);
                      void    (*eraserows)(void *c, int row, int nrows, long);
                      int     (*allocattr)(void *c, int fg, int bg, int flags,
                                      long *);
                      void    (*replaceattr)(void *c, long oldattr,
                                      long newattr);

              The cursor member defines a function for painting (or
              unpainting, depending on the on parameter) the cursor at the
              specified position.  The mapchar member defines a function for
              changing the character mapped at a given position in the
              character table.  The putchar member defines a function for
              writing a character on the screen, given its position and
              attribute.  The copycols member defines a function for copying a
              set of columns within the same line.  The erasecols member
              defines a function for clearing a set of columns in a line,
              filling the space with the given attribute.  The copyrows member
              defines a function for copying a set of complete rows.  The
              eraserows member defines a function for clearing a set of
              complete rows, filling the space with the given attribute.  The
              allocattr member defines a function for converting an attribute
              specification given by its foreground color, background color
              and flags, to the internal representation used by the underlying
              graphics driver.  The replaceattr member defines a function for
              replacing an attribute by another one across the whole visible
              part of the screen; this function is optional.

              There is a void * cookie provided by the display driver
              associated with these functions, which is passed to them when
              they are invoked.

     struct wsscreen_descr
              A structure passed to wscons by the display driver to describe a
              screen.  All displays which can operate as a console must
              provide this structure and pass it to the wsdisplay(4) child
              device.  It contains the following members:

                      char *name;
                      int ncols, nrows;
                      const struct wsdisplay_emulops *textops;
                      int fontwidth, fontheight;
                      int capabilities;

              The capabilities member is a set of flags describing the screen
              capabilities.  It can contain the following flags:

                    WSSCREEN_WSCOLORS   minimal color capability
                    WSSCREEN_REVERSE    can display reversed
                    WSSCREEN_HILIT      can highlight (however)
                    WSSCREEN_BLINK      can blink
                    WSSCREEN_UNDERLINE  can underline

     struct wsscreen_list
              A structure passed to wscons by the display driver to tell about
              its capabilities.  It contains the following members:

                      int nscreens;
                      const struct wsscreen_descr **screens;

     struct wscons_syncops
              A structure passed to wscons by the display driver describing
              the interface for external screen switching/process
              synchronization.  This structure is optional and only required
              by displays operating with terminal emulation and intending to
              support multiple screens.  It contains the following members:

                      int     (*detach)(void *, int, void (*)(), void *);
                      int     (*attach)(void *, int, void (*)(), void *);
                      int     (*check)(void *);
                      void    (*destroy)(void *);

FUNCTIONS
     wsdisplay_switchtoconsole()
              Switch the console display to its first screen.

     wsdisplay_cnattach(type, cookie, ccol, crow, defattr)
              Attach this display as the console input by specifying the
              number of columns ccol and number of rows crows.  The argument
              defattr specifies the default attribute (color) for the console.

     wsemul_xxx_cnattach(type, cookie, ccol, crow, defattr)
              Attach this display as the console with terminal emulation
              described by the xxx and specifying the number of columns ccol
              and number of rows crows.  The argument defattr specifies the
              default attribute (color) for the console.  Different terminal
              emulations can be active at the same time on one display.

     wsdisplaydevprint(aux, pnp)
              The default wsdisplay printing routine used by config_found().
              (see autoconf(9)).

     wsemuldisplaydevprint(aux, pnp)
              The default wsemul printing routine used by config_found().
              (see autoconf(9)).

AUTOCONFIGURATION
     Display drivers which want to use the wsdisplay module must be a parent
     to the wsdisplay(4) device and provide an attachment interface.  To
     attach the wsdisplay(4) device, the display driver must allocate and
     populate a wsdisplaydev_attach_args structure with the supported
     operations and callbacks and call config_found() to perform the attach
     (see autoconf(9)).

     Display drivers which want to use the wscons terminal emulation module
     must be a parent to the wsdisplay(4) device and provide a
     wsemuldisplaydev_attach_args structure instead of the standard
     wsdisplaydev_attach_args to config_found() to perform the attach.  If the
     display is not the console the attachment is the same as
     wsdisplaydev_attach_args.

OPERATION
     If the display belongs to the system console, it must describe the
     default screen by invoking wsdisplay_cnattach() at console attach time.

     All display manipulation is performed by the wscons interface by using
     the callbacks defined in the wsdisplay_accessops structure.  The ioctl()
     function is called by the wscons interface to perform display-specific
     ioctl operations (see ioctl(2)).  The argument cmd to the ioctl()
     function specifies the specific command to perform using the data data.
     Valid commands are listed in sys/dev/wscons/wsconsio.h and documented in
     wsdisplay(4).  Operations for terminal emulation are performed using the
     callbacks defined in the wsdisplay_emulops structure.

CODE REFERENCES
     The wscons subsystem is implemented within the directory sys/dev/wscons.
     The wsdisplay module itself is implemented within the file
     sys/dev/wscons/wsdisplay.c.  The terminal emulation support is
     implemented within the files sys/dev/wscons/wsemul_*.  ioctl(2)
     operations are listed in sys/dev/wscons/wsconsio.h.

SEE ALSO
     ioctl(2), wsdisplay(4), autoconf(9), driver(9), intro(9), rasops(9),
     wsfont(9), wskbd(9), wsmouse(9)

NetBSD 7.1.2                    April 15, 2006                    NetBSD 7.1.2