1 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2 Programming gameport drivers 2 Programming gameport drivers
3 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 3 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
4 4
5 A basic classic gameport 5 A basic classic gameport
6 ~~~~~~~~~~~~~~~~~~~~~~~~ 6 ~~~~~~~~~~~~~~~~~~~~~~~~
7 7
8 If the gameport doesn't provide more than the 8 If the gameport doesn't provide more than the inb()/outb() functionality,
9 the code needed to register it with the joysti 9 the code needed to register it with the joystick drivers is simple::
10 10
11 struct gameport gameport; 11 struct gameport gameport;
12 12
13 gameport.io = MY_IO_ADDRESS; 13 gameport.io = MY_IO_ADDRESS;
14 gameport_register_port(&gameport); 14 gameport_register_port(&gameport);
15 15
16 Make sure struct gameport is initialized to 0 16 Make sure struct gameport is initialized to 0 in all other fields. The
17 gameport generic code will take care of the re 17 gameport generic code will take care of the rest.
18 18
19 If your hardware supports more than one io add 19 If your hardware supports more than one io address, and your driver can
20 choose which one to program the hardware to, s 20 choose which one to program the hardware to, starting from the more exotic
21 addresses is preferred, because the likelihood 21 addresses is preferred, because the likelihood of clashing with the standard
22 0x201 address is smaller. 22 0x201 address is smaller.
23 23
24 E.g. if your driver supports addresses 0x200, !! 24 Eg. if your driver supports addresses 0x200, 0x208, 0x210 and 0x218, then
25 0x218 would be the address of first choice. 25 0x218 would be the address of first choice.
26 26
27 If your hardware supports a gameport address t 27 If your hardware supports a gameport address that is not mapped to ISA io
28 space (is above 0x1000), use that one, and don 28 space (is above 0x1000), use that one, and don't map the ISA mirror.
29 29
30 Also, always request_region() on the whole io 30 Also, always request_region() on the whole io space occupied by the
31 gameport. Although only one ioport is really u 31 gameport. Although only one ioport is really used, the gameport usually
32 occupies from one to sixteen addresses in the 32 occupies from one to sixteen addresses in the io space.
33 33
34 Please also consider enabling the gameport on 34 Please also consider enabling the gameport on the card in the ->open()
35 callback if the io is mapped to ISA space - th 35 callback if the io is mapped to ISA space - this way it'll occupy the io
36 space only when something really is using it. 36 space only when something really is using it. Disable it again in the
37 ->close() callback. You also can select the io 37 ->close() callback. You also can select the io address in the ->open()
38 callback, so that it doesn't fail if some of t 38 callback, so that it doesn't fail if some of the possible addresses are
39 already occupied by other gameports. 39 already occupied by other gameports.
40 40
41 Memory mapped gameport 41 Memory mapped gameport
42 ~~~~~~~~~~~~~~~~~~~~~~ 42 ~~~~~~~~~~~~~~~~~~~~~~
43 43
44 When a gameport can be accessed through MMIO, 44 When a gameport can be accessed through MMIO, this way is preferred, because
45 it is faster, allowing more reads per second. 45 it is faster, allowing more reads per second. Registering such a gameport
46 isn't as easy as a basic IO one, but not so mu 46 isn't as easy as a basic IO one, but not so much complex::
47 47
48 struct gameport gameport; 48 struct gameport gameport;
49 49
50 void my_trigger(struct gameport *gamep 50 void my_trigger(struct gameport *gameport)
51 { 51 {
52 my_mmio = 0xff; 52 my_mmio = 0xff;
53 } 53 }
54 54
55 unsigned char my_read(struct gameport 55 unsigned char my_read(struct gameport *gameport)
56 { 56 {
57 return my_mmio; 57 return my_mmio;
58 } 58 }
59 59
60 gameport.read = my_read; 60 gameport.read = my_read;
61 gameport.trigger = my_trigger; 61 gameport.trigger = my_trigger;
62 gameport_register_port(&gameport); 62 gameport_register_port(&gameport);
63 63
64 .. _gameport_pgm_cooked_mode: 64 .. _gameport_pgm_cooked_mode:
65 65
66 Cooked mode gameport 66 Cooked mode gameport
67 ~~~~~~~~~~~~~~~~~~~~ 67 ~~~~~~~~~~~~~~~~~~~~
68 68
69 There are gameports that can report the axis v 69 There are gameports that can report the axis values as numbers, that means
70 the driver doesn't have to measure them the ol 70 the driver doesn't have to measure them the old way - an ADC is built into
71 the gameport. To register a cooked gameport:: 71 the gameport. To register a cooked gameport::
72 72
73 struct gameport gameport; 73 struct gameport gameport;
74 74
75 int my_cooked_read(struct gameport *ga 75 int my_cooked_read(struct gameport *gameport, int *axes, int *buttons)
76 { 76 {
77 int i; 77 int i;
78 78
79 for (i = 0; i < 4; i++) 79 for (i = 0; i < 4; i++)
80 axes[i] = my_mmio[i]; 80 axes[i] = my_mmio[i];
81 buttons[0] = my_mmio[4]; !! 81 buttons[i] = my_mmio[4];
82 } 82 }
83 83
84 int my_open(struct gameport *gameport, 84 int my_open(struct gameport *gameport, int mode)
85 { 85 {
86 return -(mode != GAMEPORT_MODE 86 return -(mode != GAMEPORT_MODE_COOKED);
87 } 87 }
88 88
89 gameport.cooked_read = my_cooked_read; 89 gameport.cooked_read = my_cooked_read;
90 gameport.open = my_open; 90 gameport.open = my_open;
91 gameport.fuzz = 8; 91 gameport.fuzz = 8;
92 gameport_register_port(&gameport); 92 gameport_register_port(&gameport);
93 93
94 The only confusing thing here is the fuzz valu 94 The only confusing thing here is the fuzz value. Best determined by
95 experimentation, it is the amount of noise in 95 experimentation, it is the amount of noise in the ADC data. Perfect
96 gameports can set this to zero, most common ha 96 gameports can set this to zero, most common have fuzz between 8 and 32.
97 See analog.c and input.c for handling of fuzz 97 See analog.c and input.c for handling of fuzz - the fuzz value determines
98 the size of a gaussian filter window that is u 98 the size of a gaussian filter window that is used to eliminate the noise
99 in the data. 99 in the data.
100 100
101 More complex gameports 101 More complex gameports
102 ~~~~~~~~~~~~~~~~~~~~~~ 102 ~~~~~~~~~~~~~~~~~~~~~~
103 103
104 Gameports can support both raw and cooked mode 104 Gameports can support both raw and cooked modes. In that case combine either
105 examples 1+2 or 1+3. Gameports can support int 105 examples 1+2 or 1+3. Gameports can support internal calibration - see below,
106 and also lightning.c and analog.c on how that 106 and also lightning.c and analog.c on how that works. If your driver supports
107 more than one gameport instance simultaneously 107 more than one gameport instance simultaneously, use the ->private member of
108 the gameport struct to point to your data. 108 the gameport struct to point to your data.
109 109
110 Unregistering a gameport 110 Unregistering a gameport
111 ~~~~~~~~~~~~~~~~~~~~~~~~ 111 ~~~~~~~~~~~~~~~~~~~~~~~~
112 112
113 Simple:: 113 Simple::
114 114
115 gameport_unregister_port(&gameport); 115 gameport_unregister_port(&gameport);
116 116
117 The gameport structure 117 The gameport structure
118 ~~~~~~~~~~~~~~~~~~~~~~ 118 ~~~~~~~~~~~~~~~~~~~~~~
119 119
>> 120 .. note::
>> 121
>> 122 This section is outdated. There are several fields here that don't
>> 123 match what's there at include/linux/gameport.h.
>> 124
120 :: 125 ::
121 126
122 struct gameport { 127 struct gameport {
123 128
124 void *port_data; !! 129 void *private;
125 130
126 A private pointer for free use in the gameport 131 A private pointer for free use in the gameport driver. (Not the joystick
127 driver!) 132 driver!)
128 133
129 :: 134 ::
130 135
131 char name[32]; !! 136 int number;
132 <<
133 Driver's name as set by driver calling gamepor <<
134 purpose only. <<
135 <<
136 :: <<
137 <<
138 char phys[32]; <<
139 137
140 gameport's physical name/description as set by !! 138 Number assigned to the gameport when registered. Informational purpose only.
141 Informational purpose only. <<
142 139
143 :: 140 ::
144 141
145 int io; 142 int io;
146 143
147 I/O address for use with raw mode. You have to 144 I/O address for use with raw mode. You have to either set this, or ->read()
148 to some value if your gameport supports raw mo 145 to some value if your gameport supports raw mode.
149 146
150 :: 147 ::
151 148
152 int speed; 149 int speed;
153 150
154 Raw mode speed of the gameport reads in thousa 151 Raw mode speed of the gameport reads in thousands of reads per second.
155 152
156 :: 153 ::
157 154
158 int fuzz; 155 int fuzz;
159 156
160 If the gameport supports cooked mode, this sho 157 If the gameport supports cooked mode, this should be set to a value that
161 represents the amount of noise in the data. Se 158 represents the amount of noise in the data. See
162 :ref:`gameport_pgm_cooked_mode`. 159 :ref:`gameport_pgm_cooked_mode`.
163 160
164 :: 161 ::
165 162
166 void (*trigger)(struct gameport *); 163 void (*trigger)(struct gameport *);
167 164
168 Trigger. This function should trigger the ns55 165 Trigger. This function should trigger the ns558 oneshots. If set to NULL,
169 outb(0xff, io) will be used. 166 outb(0xff, io) will be used.
170 167
171 :: 168 ::
172 169
173 unsigned char (*read)(struct gameport 170 unsigned char (*read)(struct gameport *);
174 171
175 Read the buttons and ns558 oneshot bits. If se 172 Read the buttons and ns558 oneshot bits. If set to NULL, inb(io) will be
176 used instead. 173 used instead.
177 174
178 :: 175 ::
179 176
180 int (*cooked_read)(struct gameport *, 177 int (*cooked_read)(struct gameport *, int *axes, int *buttons);
181 178
182 If the gameport supports cooked mode, it shoul 179 If the gameport supports cooked mode, it should point this to its cooked
183 read function. It should fill axes[0..3] with 180 read function. It should fill axes[0..3] with four values of the joystick axes
184 and buttons[0] with four bits representing the 181 and buttons[0] with four bits representing the buttons.
185 182
186 :: 183 ::
187 184
188 int (*calibrate)(struct gameport *, in 185 int (*calibrate)(struct gameport *, int *axes, int *max);
189 186
190 Function for calibrating the ADC hardware. Whe 187 Function for calibrating the ADC hardware. When called, axes[0..3] should be
191 pre-filled by cooked data by the caller, max[0 188 pre-filled by cooked data by the caller, max[0..3] should be pre-filled with
192 expected maximums for each axis. The calibrate 189 expected maximums for each axis. The calibrate() function should set the
193 sensitivity of the ADC hardware so that the ma 190 sensitivity of the ADC hardware so that the maximums fit in its range and
194 recompute the axes[] values to match the new s 191 recompute the axes[] values to match the new sensitivity or re-read them from
195 the hardware so that they give valid values. 192 the hardware so that they give valid values.
196 193
197 :: 194 ::
198 195
199 int (*open)(struct gameport *, int mod 196 int (*open)(struct gameport *, int mode);
200 197
201 Open() serves two purposes. First a driver eit 198 Open() serves two purposes. First a driver either opens the port in raw or
202 in cooked mode, the open() callback can decide 199 in cooked mode, the open() callback can decide which modes are supported.
203 Second, resource allocation can happen here. T 200 Second, resource allocation can happen here. The port can also be enabled
204 here. Prior to this call, other fields of the 201 here. Prior to this call, other fields of the gameport struct (namely the io
205 member) need not to be valid. 202 member) need not to be valid.
206 203
207 :: 204 ::
208 205
209 void (*close)(struct gameport *); 206 void (*close)(struct gameport *);
210 207
211 Close() should free the resources allocated by 208 Close() should free the resources allocated by open, possibly disabling the
212 gameport. 209 gameport.
213 210
214 :: 211 ::
215 212
216 struct timer_list poll_timer; !! 213 struct gameport_dev *dev;
217 unsigned int poll_interval; /* in !! 214 struct gameport *next;
218 spinlock_t timer_lock; <<
219 unsigned int poll_cnt; <<
220 void (*poll_handler)(struct gameport * <<
221 struct gameport *parent, *child; <<
222 struct gameport_driver *drv; <<
223 struct mutex drv_mutex; /* pro <<
224 struct device dev; <<
225 struct list_head node; <<
226 215
227 For internal use by the gameport layer. 216 For internal use by the gameport layer.
228 217
229 :: 218 ::
230 219
231 }; 220 };
232 221
233 Enjoy! 222 Enjoy!
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