hid-lg3ff.c

  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
 44static int hid_lg3ff_play(struct input_dev *dev, void *data,
 45			 struct ff_effect *effect)
 46{
 47	struct hid_device *hid = input_get_drvdata(dev);
 48	struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list;
 49	struct hid_report *report = list_entry(report_list->next, struct hid_report, list);
 50	int x, y;
 51
 52/*
 53 * Available values in the field should always be 63, but we only use up to
 54 * 35. Instead, clear the entire area, however big it is.
 55 */
 56	memset(report->field[0]->value, 0,
 57	       sizeof(__s32) * report->field[0]->report_count);
 58
 59	switch (effect->type) {
 60	case FF_CONSTANT:
 61/*
 62 * Already clamped in ff_memless
 63 * 0 is center (different then other logitech)
 64 */
 65		x = effect->u.ramp.start_level;
 66		y = effect->u.ramp.end_level;
 67
 68		/* send command byte */
 69		report->field[0]->value[0] = 0x51;
 70
 71/*
 72 * Sign backwards from other Force3d pro
 73 * which get recast here in two's complement 8 bits
 74 */
 75		report->field[0]->value[1] = (unsigned char)(-x);
 76		report->field[0]->value[31] = (unsigned char)(-y);
 77
 78		hid_hw_request(hid, report, HID_REQ_SET_REPORT);
 79		break;
 80	}
 81	return 0;
 82}
 83static void hid_lg3ff_set_autocenter(struct input_dev *dev, u16 magnitude)
 84{
 85	struct hid_device *hid = input_get_drvdata(dev);
 86	struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list;
 87	struct hid_report *report = list_entry(report_list->next, struct hid_report, list);
 88
 89/*
 90 * Auto Centering probed from device
 91 * NOTE: deadman's switch on G940 must be covered
 92 * for effects to work
 93 */
 94	report->field[0]->value[0] = 0x51;
 95	report->field[0]->value[1] = 0x00;
 96	report->field[0]->value[2] = 0x00;
 97	report->field[0]->value[3] = 0x7F;
 98	report->field[0]->value[4] = 0x7F;
 99	report->field[0]->value[31] = 0x00;
100	report->field[0]->value[32] = 0x00;
101	report->field[0]->value[33] = 0x7F;
102	report->field[0]->value[34] = 0x7F;
103
104	hid_hw_request(hid, report, HID_REQ_SET_REPORT);
105}
106
107
108static const signed short ff3_joystick_ac[] = {
109	FF_CONSTANT,
110	FF_AUTOCENTER,
111	-1
112};
113
114int lg3ff_init(struct hid_device *hid)
115{
116	struct hid_input *hidinput;
117	struct input_dev *dev;
118	const signed short *ff_bits = ff3_joystick_ac;
119	int error;
120	int i;
121
122	if (list_empty(&hid->inputs)) {
123		hid_err(hid, "no inputs found\n");
124		return -ENODEV;
125	}
126	hidinput = list_entry(hid->inputs.next, struct hid_input, list);
127	dev = hidinput->input;
128
129	/* Check that the report looks ok */
130	if (!hid_validate_values(hid, HID_OUTPUT_REPORT, 0, 0, 35))
131		return -ENODEV;
132
133	/* Assume single fixed device G940 */
134	for (i = 0; ff_bits[i] >= 0; i++)
135		set_bit(ff_bits[i], dev->ffbit);
136
137	error = input_ff_create_memless(dev, NULL, hid_lg3ff_play);
138	if (error)
139		return error;
140
141	if (test_bit(FF_AUTOCENTER, dev->ffbit))
142		dev->ff->set_autocenter = hid_lg3ff_set_autocenter;
143
144	hid_info(hid, "Force feedback for Logitech Flight System G940 by Gary Stein <LordCnidarian@gmail.com>\n");
145	return 0;
146}
147