drivers/hid/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
  44 static 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 }
  83 static 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
 108 static const signed short ff3_joystick_ac[] = {
 109         FF_CONSTANT,
 110         FF_AUTOCENTER,
 111         -1
 112 };
 113
 114 int 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