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Diffstat (limited to 'Documentation/input/gameport-programming.txt')
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diff --git a/Documentation/input/gameport-programming.txt b/Documentation/input/gameport-programming.txt deleted file mode 100644 index 03a74fc3b496..000000000000 --- a/Documentation/input/gameport-programming.txt +++ /dev/null @@ -1,187 +0,0 @@ -Programming gameport drivers -~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -1. 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: - - struct gameport gameport; - - gameport.io = MY_IO_ADDRESS; - gameport_register_port(&gameport); - -Make sure struct gameport is initialized to 0 in all other fields. The -gameport generic code will take care of the rest. - -If your hardware supports more than one io address, and your driver can -choose which one to program the hardware to, starting from the more exotic -addresses is preferred, because the likelihood of clashing with the standard -0x201 address is smaller. - -Eg. if your driver supports addresses 0x200, 0x208, 0x210 and 0x218, then -0x218 would be the address of first choice. - -If your hardware supports a gameport address that is not mapped to ISA io -space (is above 0x1000), use that one, and don't map the ISA mirror. - -Also, always request_region() on the whole io space occupied by the -gameport. Although only one ioport is really used, the gameport usually -occupies from one to sixteen addresses in the io space. - -Please also consider enabling the gameport on the card in the ->open() -callback if the io is mapped to ISA space - this way it'll occupy the io -space only when something really is using it. Disable it again in the -->close() callback. You also can select the io address in the ->open() -callback, so that it doesn't fail if some of the possible addresses are -already occupied by other gameports. - -2. 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: - - struct gameport gameport; - - void my_trigger(struct gameport *gameport) - { - my_mmio = 0xff; - } - - unsigned char my_read(struct gameport *gameport) - { - return my_mmio; - } - - gameport.read = my_read; - gameport.trigger = my_trigger; - gameport_register_port(&gameport); - -3. 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: - - struct gameport gameport; - - int my_cooked_read(struct gameport *gameport, int *axes, int *buttons) - { - int i; - - for (i = 0; i < 4; i++) - axes[i] = my_mmio[i]; - buttons[i] = my_mmio[4]; - } - - int my_open(struct gameport *gameport, int mode) - { - return -(mode != GAMEPORT_MODE_COOKED); - } - - gameport.cooked_read = my_cooked_read; - gameport.open = my_open; - gameport.fuzz = 8; - gameport_register_port(&gameport); - -The only confusing thing here is the fuzz value. Best determined by -experimentation, it is the amount of noise in the ADC data. Perfect -gameports can set this to zero, most common have fuzz between 8 and 32. -See analog.c and input.c for handling of fuzz - the fuzz value determines -the size of a gaussian filter window that is used to eliminate the noise -in the data. - -4. 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, -and also lightning.c and analog.c on how that works. If your driver supports -more than one gameport instance simultaneously, use the ->private member of -the gameport struct to point to your data. - -5. Unregistering a gameport -~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Simple: - -gameport_unregister_port(&gameport); - -6. The gameport structure -~~~~~~~~~~~~~~~~~~~~~~~~~ - -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. - - 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); - -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); - -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. - - int (*open)(struct gameport *, int mode); - -Open() serves two purposes. First a driver either opens the port in raw or -in cooked mode, the open() callback can decide which modes are supported. -Second, resource allocation can happen here. The port can also be enabled -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! |