1/*
2 * Force feedback support for Logitech Flight System G940
3 *
4 * Copyright (c) 2009 Gary Stein <LordCnidarian@gmail.com>
5 */
6
7/*
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 */
22
23
24#include <linux/input.h>
25#include <linux/hid.h>
26
27#include "hid-lg.h"
28
29/*
30 * G940 Theory of Operation (from experimentation)
31 *
32 * There are 63 fields (only 3 of them currently used)
33 * 0 - seems to be command field
34 * 1 - 30 deal with the x axis
35 * 31 -60 deal with the y axis
36 *
37 * Field 1 is x axis constant force
38 * Field 31 is y axis constant force
39 *
40 * other interesting fields 1,2,3,4 on x axis
41 * (same for 31,32,33,34 on y axis)
42 *
43 * 0 0 127 127 makes the joystick autocenter hard
44 *
45 * 127 0 127 127 makes the joystick loose on the right,
46 * but stops all movemnt left
47 *
48 * -127 0 -127 -127 makes the joystick loose on the left,
49 * but stops all movement right
50 *
51 * 0 0 -127 -127 makes the joystick rattle very hard
52 *
53 * I'm sure these are effects that I don't know enough about them
54 */
55
56struct lg3ff_device {
57 struct hid_report *report;
58};
59
60static int hid_lg3ff_play(struct input_dev *dev, void *data,
61 struct ff_effect *effect)
62{
63 struct hid_device *hid = input_get_drvdata(dev);
64 struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list;
65 struct hid_report *report = list_entry(report_list->next, struct hid_report, list);
66 int x, y;
67
68/*
69 * Available values in the field should always be 63, but we only use up to
70 * 35. Instead, clear the entire area, however big it is.
71 */
72 memset(report->field[0]->value, 0,
73 sizeof(__s32) * report->field[0]->report_count);
74
75 switch (effect->type) {
76 case FF_CONSTANT:
77/*
78 * Already clamped in ff_memless
79 * 0 is center (different then other logitech)
80 */
81 x = effect->u.ramp.start_level;
82 y = effect->u.ramp.end_level;
83
84 /* send command byte */
85 report->field[0]->value[0] = 0x51;
86
87/*
88 * Sign backwards from other Force3d pro
89 * which get recast here in two's complement 8 bits
90 */
91 report->field[0]->value[1] = (unsigned char)(-x);
92 report->field[0]->value[31] = (unsigned char)(-y);
93
94 hid_hw_request(hid, report, HID_REQ_SET_REPORT);
95 break;
96 }
97 return 0;
98}
99static void hid_lg3ff_set_autocenter(struct input_dev *dev, u16 magnitude)
100{
101 struct hid_device *hid = input_get_drvdata(dev);
102 struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list;
103 struct hid_report *report = list_entry(report_list->next, struct hid_report, list);
104
105/*
106 * Auto Centering probed from device
107 * NOTE: deadman's switch on G940 must be covered
108 * for effects to work
109 */
110 report->field[0]->value[0] = 0x51;
111 report->field[0]->value[1] = 0x00;
112 report->field[0]->value[2] = 0x00;
113 report->field[0]->value[3] = 0x7F;
114 report->field[0]->value[4] = 0x7F;
115 report->field[0]->value[31] = 0x00;
116 report->field[0]->value[32] = 0x00;
117 report->field[0]->value[33] = 0x7F;
118 report->field[0]->value[34] = 0x7F;
119
120 hid_hw_request(hid, report, HID_REQ_SET_REPORT);
121}
122
123
124static const signed short ff3_joystick_ac[] = {
125 FF_CONSTANT,
126 FF_AUTOCENTER,
127 -1
128};
129
130int lg3ff_init(struct hid_device *hid)
131{
132 struct hid_input *hidinput = list_entry(hid->inputs.next, struct hid_input, list);
133 struct input_dev *dev = hidinput->input;
134 const signed short *ff_bits = ff3_joystick_ac;
135 int error;
136 int i;
137
138 /* Check that the report looks ok */
139 if (!hid_validate_values(hid, HID_OUTPUT_REPORT, 0, 0, 35))
140 return -ENODEV;
141
142 /* Assume single fixed device G940 */
143 for (i = 0; ff_bits[i] >= 0; i++)
144 set_bit(ff_bits[i], dev->ffbit);
145
146 error = input_ff_create_memless(dev, NULL, hid_lg3ff_play);
147 if (error)
148 return error;
149
150 if (test_bit(FF_AUTOCENTER, dev->ffbit))
151 dev->ff->set_autocenter = hid_lg3ff_set_autocenter;
152
153 hid_info(hid, "Force feedback for Logitech Flight System G940 by Gary Stein <LordCnidarian@gmail.com>\n");
154 return 0;
155}
156
157