root/drivers/hid/hid-lg3ff.c

DEFINITIONS

1. hid_lg3ff_play
2. hid_lg3ff_set_autocenter
3. lg3ff_init

   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