// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Force feedback support for Logitech Flight System G940
*
* Copyright (c) 2009 Gary Stein <[email protected]>
*/
/*
*/
#include <linux/input.h>
#include <linux/hid.h>
#include "hid-lg.h"
/*
* G940 Theory of Operation (from experimentation)
*
* There are 63 fields (only 3 of them currently used)
* 0 - seems to be command field
* 1 - 30 deal with the x axis
* 31 -60 deal with the y axis
*
* Field 1 is x axis constant force
* Field 31 is y axis constant force
*
* other interesting fields 1,2,3,4 on x axis
* (same for 31,32,33,34 on y axis)
*
* 0 0 127 127 makes the joystick autocenter hard
*
* 127 0 127 127 makes the joystick loose on the right,
* but stops all movemnt left
*
* -127 0 -127 -127 makes the joystick loose on the left,
* but stops all movement right
*
* 0 0 -127 -127 makes the joystick rattle very hard
*
* I'm sure these are effects that I don't know enough about them
*/
static int hid_lg3ff_play(struct input_dev *dev, void *data,
struct ff_effect *effect)
{
struct hid_device *hid = input_get_drvdata(dev);
struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list;
struct hid_report *report = list_entry(report_list->next, struct hid_report, list);
int x, y;
/*
* Available values in the field should always be 63, but we only use up to
* 35. Instead, clear the entire area, however big it is.
*/
memset(report->field[0]->value, 0,
sizeof(__s32) * report->field[0]->report_count);
switch (effect->type) {
case FF_CONSTANT:
/*
* Already clamped in ff_memless
* 0 is center (different then other logitech)
*/
x = effect->u.ramp.start_level;
y = effect->u.ramp.end_level;
/* send command byte */
report->field[0]->value[0] = 0x51;
/*
* Sign backwards from other Force3d pro
* which get recast here in two's complement 8 bits
*/
report->field[0]->value[1] = (unsigned char)(-x);
report->field[0]->value[31] = (unsigned char)(-y);
hid_hw_request(hid, report, HID_REQ_SET_REPORT);
break;
}
return 0;
}
static void hid_lg3ff_set_autocenter(struct input_dev *dev, u16 magnitude)
{
struct hid_device *hid = input_get_drvdata(dev);
struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list;
struct hid_report *report = list_entry(report_list->next, struct hid_report, list);
/*
* Auto Centering probed from device
* NOTE: deadman's switch on G940 must be covered
* for effects to work
*/
report->field[0]->value[0] = 0x51;
report->field[0]->value[1] = 0x00;
report->field[0]->value[2] = 0x00;
report->field[0]->value[3] = 0x7F;
report->field[0]->value[4] = 0x7F;
report->field[0]->value[31] = 0x00;
report->field[0]->value[32] = 0x00;
report->field[0]->value[33] = 0x7F;
report->field[0]->value[34] = 0x7F;
hid_hw_request(hid, report, HID_REQ_SET_REPORT);
}
static const signed short ff3_joystick_ac[] = {
FF_CONSTANT,
FF_AUTOCENTER,
-1
};
int lg3ff_init(struct hid_device *hid)
{
struct hid_input *hidinput;
struct input_dev *dev;
const signed short *ff_bits = ff3_joystick_ac;
int error;
int i;
if (list_empty(&hid->inputs)) {
hid_err(hid, "no inputs found\n");
return -ENODEV;
}
hidinput = list_entry(hid->inputs.next, struct hid_input, list);
dev = hidinput->input;
/* Check that the report looks ok */
if (!hid_validate_values(hid, HID_OUTPUT_REPORT, 0, 0, 35))
return -ENODEV;
/* Assume single fixed device G940 */
for (i = 0; ff_bits[i] >= 0; i++)
set_bit(ff_bits[i], dev->ffbit);
error = input_ff_create_memless(dev, NULL, hid_lg3ff_play);
if (error)
return error;
if (test_bit(FF_AUTOCENTER, dev->ffbit))
dev->ff->set_autocenter = hid_lg3ff_set_autocenter;
hid_info(hid, "Force feedback for Logitech Flight System G940 by Gary Stein <[email protected]>\n");
return 0;
}
Codebase Browser
linux