1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Force feedback support for Logitech Flight System G940 4 * 5 * Copyright (c) 2009 Gary Stein <LordCnidarian@gmail.com> 6 */ 7 8 /* 9 */ 10 11 12 #include <linux/input.h> 13 #include <linux/hid.h> 14 15 #include "hid-lg.h" 16 17 /* 18 * G940 Theory of Operation (from experimentation) 19 * 20 * There are 63 fields (only 3 of them currently used) 21 * 0 - seems to be command field 22 * 1 - 30 deal with the x axis 23 * 31 -60 deal with the y axis 24 * 25 * Field 1 is x axis constant force 26 * Field 31 is y axis constant force 27 * 28 * other interesting fields 1,2,3,4 on x axis 29 * (same for 31,32,33,34 on y axis) 30 * 31 * 0 0 127 127 makes the joystick autocenter hard 32 * 33 * 127 0 127 127 makes the joystick loose on the right, 34 * but stops all movemnt left 35 * 36 * -127 0 -127 -127 makes the joystick loose on the left, 37 * but stops all movement right 38 * 39 * 0 0 -127 -127 makes the joystick rattle very hard 40 * 41 * I'm sure these are effects that I don't know enough about them 42 */ 43 44 struct lg3ff_device { 45 struct hid_report *report; 46 }; 47 48 static int hid_lg3ff_play(struct input_dev *dev, void *data, 49 struct ff_effect *effect) 50 { 51 struct hid_device *hid = input_get_drvdata(dev); 52 struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list; 53 struct hid_report *report = list_entry(report_list->next, struct hid_report, list); 54 int x, y; 55 56 /* 57 * Available values in the field should always be 63, but we only use up to 58 * 35. Instead, clear the entire area, however big it is. 59 */ 60 memset(report->field[0]->value, 0, 61 sizeof(__s32) * report->field[0]->report_count); 62 63 switch (effect->type) { 64 case FF_CONSTANT: 65 /* 66 * Already clamped in ff_memless 67 * 0 is center (different then other logitech) 68 */ 69 x = effect->u.ramp.start_level; 70 y = effect->u.ramp.end_level; 71 72 /* send command byte */ 73 report->field[0]->value[0] = 0x51; 74 75 /* 76 * Sign backwards from other Force3d pro 77 * which get recast here in two's complement 8 bits 78 */ 79 report->field[0]->value[1] = (unsigned char)(-x); 80 report->field[0]->value[31] = (unsigned char)(-y); 81 82 hid_hw_request(hid, report, HID_REQ_SET_REPORT); 83 break; 84 } 85 return 0; 86 } 87 static void hid_lg3ff_set_autocenter(struct input_dev *dev, u16 magnitude) 88 { 89 struct hid_device *hid = input_get_drvdata(dev); 90 struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list; 91 struct hid_report *report = list_entry(report_list->next, struct hid_report, list); 92 93 /* 94 * Auto Centering probed from device 95 * NOTE: deadman's switch on G940 must be covered 96 * for effects to work 97 */ 98 report->field[0]->value[0] = 0x51; 99 report->field[0]->value[1] = 0x00; 100 report->field[0]->value[2] = 0x00; 101 report->field[0]->value[3] = 0x7F; 102 report->field[0]->value[4] = 0x7F; 103 report->field[0]->value[31] = 0x00; 104 report->field[0]->value[32] = 0x00; 105 report->field[0]->value[33] = 0x7F; 106 report->field[0]->value[34] = 0x7F; 107 108 hid_hw_request(hid, report, HID_REQ_SET_REPORT); 109 } 110 111 112 static const signed short ff3_joystick_ac[] = { 113 FF_CONSTANT, 114 FF_AUTOCENTER, 115 -1 116 }; 117 118 int lg3ff_init(struct hid_device *hid) 119 { 120 struct hid_input *hidinput; 121 struct input_dev *dev; 122 const signed short *ff_bits = ff3_joystick_ac; 123 int error; 124 int i; 125 126 if (list_empty(&hid->inputs)) { 127 hid_err(hid, "no inputs found\n"); 128 return -ENODEV; 129 } 130 hidinput = list_entry(hid->inputs.next, struct hid_input, list); 131 dev = hidinput->input; 132 133 /* Check that the report looks ok */ 134 if (!hid_validate_values(hid, HID_OUTPUT_REPORT, 0, 0, 35)) 135 return -ENODEV; 136 137 /* Assume single fixed device G940 */ 138 for (i = 0; ff_bits[i] >= 0; i++) 139 set_bit(ff_bits[i], dev->ffbit); 140 141 error = input_ff_create_memless(dev, NULL, hid_lg3ff_play); 142 if (error) 143 return error; 144 145 if (test_bit(FF_AUTOCENTER, dev->ffbit)) 146 dev->ff->set_autocenter = hid_lg3ff_set_autocenter; 147 148 hid_info(hid, "Force feedback for Logitech Flight System G940 by Gary Stein <LordCnidarian@gmail.com>\n"); 149 return 0; 150 } 151 152