+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Programming gameport drivers
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-1. A basic classic gameport
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
+A basic classic gameport
+~~~~~~~~~~~~~~~~~~~~~~~~
If the gameport doesn't provide more than the inb()/outb() functionality,
-the code needed to register it with the joystick drivers is simple:
+the code needed to register it with the joystick drivers is simple::
struct gameport gameport;
callback, so that it doesn't fail if some of the possible addresses are
already occupied by other gameports.
-2. Memory mapped gameport
-~~~~~~~~~~~~~~~~~~~~~~~~~
+Memory mapped gameport
+~~~~~~~~~~~~~~~~~~~~~~
When a gameport can be accessed through MMIO, this way is preferred, because
it is faster, allowing more reads per second. Registering such a gameport
-isn't as easy as a basic IO one, but not so much complex:
+isn't as easy as a basic IO one, but not so much complex::
struct gameport gameport;
unsigned char my_read(struct gameport *gameport)
{
- return my_mmio;
+ return my_mmio;
}
gameport.read = my_read;
gameport.trigger = my_trigger;
gameport_register_port(&gameport);
-3. Cooked mode gameport
-~~~~~~~~~~~~~~~~~~~~~~~
+.. _gameport_pgm_cooked_mode:
+
+Cooked mode gameport
+~~~~~~~~~~~~~~~~~~~~
There are gameports that can report the axis values as numbers, that means
the driver doesn't have to measure them the old way - an ADC is built into
-the gameport. To register a cooked gameport:
+the gameport. To register a cooked gameport::
struct gameport gameport;
the size of a gaussian filter window that is used to eliminate the noise
in the data.
-4. More complex gameports
-~~~~~~~~~~~~~~~~~~~~~~~~~
+More complex gameports
+~~~~~~~~~~~~~~~~~~~~~~
Gameports can support both raw and cooked modes. In that case combine either
examples 1+2 or 1+3. Gameports can support internal calibration - see below,
more than one gameport instance simultaneously, use the ->private member of
the gameport struct to point to your data.
-5. Unregistering a gameport
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Unregistering a gameport
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+Simple::
+
+ gameport_unregister_port(&gameport);
+
+The gameport structure
+~~~~~~~~~~~~~~~~~~~~~~
-Simple:
+.. note::
-gameport_unregister_port(&gameport);
+ This section is outdated. There are several fields here that don't
+ match what's there at include/linux/gameport.h.
-6. The gameport structure
-~~~~~~~~~~~~~~~~~~~~~~~~~
+::
-struct gameport {
+ struct gameport {
void *private;
A private pointer for free use in the gameport driver. (Not the joystick
driver!)
+::
+
int number;
Number assigned to the gameport when registered. Informational purpose only.
+::
+
int io;
I/O address for use with raw mode. You have to either set this, or ->read()
to some value if your gameport supports raw mode.
+::
+
int speed;
Raw mode speed of the gameport reads in thousands of reads per second.
+::
+
int fuzz;
If the gameport supports cooked mode, this should be set to a value that
-represents the amount of noise in the data. See section 3.
+represents the amount of noise in the data. See
+:ref:`gameport_pgm_cooked_mode`.
+
+::
void (*trigger)(struct gameport *);
Trigger. This function should trigger the ns558 oneshots. If set to NULL,
outb(0xff, io) will be used.
+::
+
unsigned char (*read)(struct gameport *);
Read the buttons and ns558 oneshot bits. If set to NULL, inb(io) will be
used instead.
- int (*cooked_read)(struct gameport *, int *axes, int *buttons);
+::
+
+ int (*cooked_read)(struct gameport *, int *axes, int *buttons);
If the gameport supports cooked mode, it should point this to its cooked
read function. It should fill axes[0..3] with four values of the joystick axes
and buttons[0] with four bits representing the buttons.
- int (*calibrate)(struct gameport *, int *axes, int *max);
+::
+
+ int (*calibrate)(struct gameport *, int *axes, int *max);
Function for calibrating the ADC hardware. When called, axes[0..3] should be
pre-filled by cooked data by the caller, max[0..3] should be pre-filled with
expected maximums for each axis. The calibrate() function should set the
sensitivity of the ADC hardware so that the maximums fit in its range and
recompute the axes[] values to match the new sensitivity or re-read them from
-the hardware so that they give valid values.
+the hardware so that they give valid values.
+
+::
int (*open)(struct gameport *, int mode);
here. Prior to this call, other fields of the gameport struct (namely the io
member) need not to be valid.
+::
+
void (*close)(struct gameport *);
Close() should free the resources allocated by open, possibly disabling the
gameport.
+::
+
struct gameport_dev *dev;
struct gameport *next;
For internal use by the gameport layer.
-};
+::
+
+ };
Enjoy!