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WSDISPLAY(4) Device Drivers Manual WSDISPLAY(4)

wsdisplay — generic display device support in wscons

wsdisplay* at ...
option WSDISPLAY_DEFAULTSCREENS=N

The wsdisplay driver is an abstraction layer for display devices within the wscons(4) framework. It attaches to the hardware specific display device driver and makes it available as text terminal or graphics interface.

Display devices have the ability to display characters on them (without help of an X server), either directly by hardware or through software drawing pixel data into the display memory. The wsdisplay driver will connect a terminal emulation module and provide a tty-like software interface.

The locator in the configuration line refers to the device's use as output part of the operating system console. A device specification containing a positive value here will only match if the device is in use as system console. (The console device selection in early system startup is not influenced.) This way, the console device can be connected to a known wsdisplay device instance.

The locator in the configuration line refers to the wsmux(4) that will be used to get keyboard events. If this locator is -1 no mux will be used.

The logical unit of an independent contents displayed on a display (sometimes referred to as “virtual terminal”) is called a “screen” here. If the underlying device driver supports it, multiple screens can be used on one display. (As of this writing, only the lcd(4) and vga(4) display drivers provide this ability.) Screens have different minor device numbers and separate tty instances. One screen possesses the “focus”, this means it is displayed on the display and its tty device will get the keyboard input. (In some cases, if no screen is set up or if a screen was just deleted, it is possible that no focus is present at all.) The focus can be switched by either special keyboard input (typically CTL-ALT-Fn) or an ioctl command issued by a user program. Screens are set up or deleted through the /dev/ttyCcfg control device (preferably using the wsconscfg(8) utility). Alternatively, the compile-time option WSDISPLAY_DEFAULTSCREENS=N will set up N screens of the display driver's default type and using the system's default terminal emulator at autoconfiguration time.

In addition and with help from backend drivers the following features are also provided:

Consult the back-end drivers' documentation for which features are supported for each particular hardware type.

The following ioctl(2) calls are provided by the wsdisplay driver or by devices which use it. Their definitions are found in <dev/wscons/wsconsio.h>.

(u_int)
Retrieve the type of the display. The list of types is in <dev/wscons/wsconsio.h>.
(struct wsdisplay_fbinfo)
Retrieve basic information about a framebuffer display. The returned structure is as follows: 
struct wsdisplay_fbinfo {
        u_int   height;
        u_int   width;
        u_int   depth;
        u_int   cmsize;
};

The height and width members are counted in pixels. The depth member indicates the number of bits per pixel, and cmsize indicates the number of color map entries accessible through WSDISPLAYIO_GETCMAP and WSDISPLAYIO_PUTCMAP. This call is likely to be unavailable on text-only displays.

(struct wsdisplay_cmap)
Retrieve the current color map from the display. This call needs the following structure set up beforehand: 
struct wsdisplay_cmap {
        u_int   index;
        u_int   count;
        u_char  *red;
        u_char  *green;
        u_char  *blue;
};

The index and count members specify the range of color map entries to retrieve. The red, green, and blue members should each point to an array of count u_chars. On return, these will be filled in with the appropriate entries from the color map. On all displays that support this call, values range from 0 for minimum intensity to 255 for maximum intensity, even if the display does not use eight bits internally to represent intensity.

(struct wsdisplay_cmap)
Change the display's color map. The argument structure is the same as for WSDISPLAYIO_GETCMAP, but red, green, and blue are taken as pointers to the values to use to set the color map. This call is not available on displays with fixed color maps.
(u_int)
Get the current state of the display's video output. Possible values are:
The display is blanked.
The display is enabled.
(u_int)
Set the state of the display's video output. See WSDISPLAYIO_GVIDEO above for possible values.
(struct wsdisplay_curpos)
Retrieve the current position of the hardware cursor. The returned structure is as follows: 
struct wsdisplay_curpos {
        u_int x, y;
};

The x and y members count the number of pixels right and down, respectively, from the top-left corner of the display to the hot spot of the cursor. This call is not available on displays without a hardware cursor.

(struct wsdisplay_curpos)
Set the current cursor position. The argument structure, and its semantics, are the same as for WSDISPLAYIO_GCURPOS. This call is not available on displays without a hardware cursor.
(struct wsdisplay_curpos)
Retrieve the maximum size of cursor supported by the display. The x and y members of the returned structure indicate the maximum number of pixel rows and columns, respectively, in a hardware cursor on this display. This call is not available on displays without a hardware cursor.
(struct wsdisplay_cursor)
Retrieve some or all of the hardware cursor's attributes. The argument structure is as follows: 
struct wsdisplay_cursor {
        u_int   which;
        u_int   enable;
        struct wsdisplay_curpos pos;
        struct wsdisplay_curpos hot;
        struct wsdisplay_cmap cmap;
        struct wsdisplay_curpos size;
        u_char *image;
        u_char *mask;
};
The which member indicates which of the values the application requires to be returned. It should contain the logical OR of the following flags:
Get enable, which indicates whether the cursor is currently displayed (non-zero) or not (zero).
Get pos, which indicates the current position of the cursor on the display, as would be returned by WSDISPLAYIO_GCURPOS.
Get hot, which indicates the location of the “hot spot” within the cursor. This is the point on the cursor whose position on the display is treated as being the position of the cursor by other calls. Its location is counted in pixels from the top-left corner of the cursor.
Get cmap, which indicates the current cursor color map. Unlike in a call to WSDISPLAYIO_GETCMAP, cmap here need not have its index and count members initialized. They will be set to 0 and 2 respectively by the call. This means that cmap.red, cmap.green, and cmap.blue must each point to at least enough space to hold two u_chars.
Get size, image, and mask. These are, respectively, the dimensions of the cursor in pixels, the bitmap of set pixels in the cursor and the bitmap of opaque pixels in the cursor. The format in which these bitmaps are returned, and hence the amount of space that must be provided by the application, are device-dependent.
Get all of the above.

The device may elect to return information that was not requested by the user, so those elements of struct wsdisplay_cursor which are pointers should be initialized to NULL if not otherwise used. This call is not available on displays without a hardware cursor.

(struct wsdisplay_cursor)
Set some or all of the hardware cursor's attributes. The argument structure is the same as for WSDISPLAYIO_GCURSOR. The which member specifies which attributes of the cursor are to be changed. It should contain the logical OR of the following flags:
If enable is zero, hide the cursor. Otherwise, display it.
Set the cursor's position on the display to pos, the same as WSDISPLAYIO_SCURPOS.
Set the “hot spot” of the cursor, as defined above, to hot.
Set some or all of the cursor color map based on cmap. The index and count elements of cmap indicate which color map entries to set, and the entries themselves come from cmap.red, cmap.green, and cmap.blue.
Set the cursor shape from size, image, mask. See above for their meanings.
Do all of the above.

This call is not available on displays without a hardware cursor.

(u_int)
Get the current mode of the display. Possible results include:
The display is in emulating (text) mode.
The display is in mapped (graphics) mode.
The display is in mapped (frame buffer) mode.
(u_int)
Set the current mode of the display. For possible arguments, see WSDISPLAYIO_GMODE.
(struct wsdisplay_font)
Loads a font specified by the wsdisplay_font structure. 
struct wsdisplay_font {
        char name[WSFONT_NAME_SIZE];
        int index;
        int firstchar, numchars;
        int encoding;
        u_int fontwidth, fontheight, stride;
        int bitorder, byteorder;
        void *cookie;
        void *data;
};

The name field contains a human readable string used to identify the font. The index field may be used to select a driver-specific font resource (for non-raster frame buffers). A value of -1 will pick the first available slot. The firstchar field contains the index of the first character in the font, starting at zero. The numchars field contains the number of characters in the font. The encoding field describes the font character encoding, using one of the following values:

ISO-8859-1 encoding (also known as Latin-1). This is the preferred encoding for raster frame buffers.
IBM code page number 437. This is the preferred encoding for text-mode displays.

The fontwidth and fontheight fields specify the dimensions of a character cell. The stride field specify the number of bytes of font data per character cell line (usually fontwidth rounded up to a byte boundary). The bitorder and byteorder fields specify the bit- and byte-ordering of the font data, using either one of the following values:

Leftmost data contained in the most significant bits (left-to-right ordering). This is the most commonly encountered case.
Leftmost data contained in the least significant bits (right-to-left ordering).

The data field contains the font character data to be loaded. The cookie field is reserved for internal purposes.

(struct wsdisplay_font)
Retrieves the data for a loaded font into the wsdisplay_font structure. The index field is set to the font resource to query. For the argument structure, see WSDISPLAYIO_LDFONT.
WSDISPLAYIO_USEFONT (struct wsdisplay_font)
Selects the font specified in the name field. An empty name selects the next available font. For the argument structure, see WSDISPLAYIO_LDFONT.
(struct wsdisplay_burner)
Retrieves the state of the screen burner. The returned structure is as follows: 
struct wsdisplay_burner {
        u_int   off;
        u_int   on;
        u_int   flags;
};

The off member contains the inactivity time before the screen is turned off, in milliseconds. The on member contains the time before the screen is turned back on, in milliseconds. The flags member contains a logical OR of the following flags:

When turning the display off, disable the vertical synchronization signal.
Monitor keyboard activity.
Monitor mouse activity (this only works for mice using the wsmouse(4) driver).
Monitor display output activity.

If none of the activity source flags are set, the screen burner is disabled.

(struct wsdisplay_burner)
Sets the state of the screen burner. The argument structure, and its semantics, are the same as for WSDISPLAYIO_GBURNER.
(struct wsdisplay_addscreendata)
Creates a new screen. 
struct wsdisplay_addscreendata {
        int idx; /* screen index */
        char screentype[WSSCREEN_NAME_SIZE];
        char emul[WSEMUL_NAME_SIZE];
};

The idx field is the index of the screen to be configured. The screentype field is matched against builtin screen types, which will be driver-dependent. The emul field indicates the terminal emulation type. Available terminal emulations are:

sun
Sun terminal emulation. This is the default on the sparc64 architecture.
vt100
Dec VT100 terminal emulation, with some VT220 features. This is the default on all other architectures.
dumb
Dumb terminal.

An empty string will select the default emulation.

(struct wsdisplay_delscreendata)
Deletes an existing screen. 
struct wsdisplay_delscreendata {
        int idx; /* screen index */
        int flags;
};

The idx field indicates the index of the screen to be deleted. The flags field is a logical OR of zero or more of the following:

Force deletion of screen even if in use by a userspace program.
Don't report deletion to console.
(struct wsdisplay_addscreendata)
Returns information on the screen indicated by idx or the current screen if idx is -1. The screen and emulation types are returned in the same structure (see WSDISPLAYIO_GETPARAM).
(u_int)
Switch to the screen with the given index.
(struct wscons_event)
This call is used by the wsmoused(8) daemon to inject mouse events gathered from serial mice, as well as various control events.
(struct wsdisplay_param)
Retrieves the state of a display parameter. This call needs the following structure set up beforehand: 
struct wsdisplay_param {
        int param;
        int min, max, curval;
        int reserved[4];
};

The param member should be set with the parameter to be returned. The following parameters are supported:

The intensity of the display backlight (usually on laptop computers).
The brightness level.
The contrast level.

On return, min and max specify the allowed range for the value, while curval specifies the current setting. Not all parameters are supported by all display drivers.

(struct wsdisplay_param)
Sets a display parameter. The argument structure is the same as for WSDISPLAYIO_GETPARAM, with the param and curval members filled in. Not all parameters are supported by all display drivers.
(u_int)
Get the number of bytes per row when the device is in WSDISPLAYIO_MODE_DUMBFB mode.

/dev/tty[C-F]*
terminal devices (per screen)
/dev/tty[C-F]cfg
control device (per screen)
/usr/include/dev/wscons/wsconsio.h
 

intro(4), tty(4), wscons(4), wsmux(4), wsconscfg(8), wsconsctl(8), wsfontload(8)

The wsdisplay code currently limits the number of screens on one display to 8.

The terms “wscons” and “wsdisplay” are not cleanly distinguished in the code and in manual pages.

September 1, 2016 OpenBSD-6.1