WSDISPLAY(9) BSD 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 start‐
ing 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 func‐
tion for mapping a part of the display device into user address
space. The alloc_screen member defines a function for allocat‐
ing 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 func‐
tion 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 associ‐
ated 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 mem‐
bers:
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 pro‐
vide 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 unpaint‐
ing, 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 mem‐
ber 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 representa‐
tion 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 associ‐
ated 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 pro‐
vide 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 synchroniza‐
tion. This structure is optional and only required by displays
operating with terminal emulation and intending to support mul‐
tiple screens. It contains the following members:
int (*detach)(void *, int, void (*)(), void *);
int (*attach)(void *, int, void (*)(), void *);
int (*check)(void *);
void (*destroy)(void *);
FUNCTIONSwsdisplay_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 num‐
ber 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 pop‐
ulate 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 wsdisplay‐
dev_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() func‐
tion 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 imple‐
mented within the files sys/dev/wscons/wsemul_*. ioctl(2) operations are
listed in sys/dev/wscons/wsconsio.h.
SEE ALSOioctl(2), wsdisplay(4), autoconf(9), driver(9), intro(9), rasops(9),
wsfont(9), wskbd(9), wsmouse(9)BSD April 15, 2006 BSD
