drivers/hid/hid-emsff.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Force feedback support for EMS Trio Linker Plus II
   4  *
   5  *  Copyright (c) 2010 Ignaz Forster <ignaz.forster@gmx.de>
   6  */
   7
   8 /*
   9  */
  10
  11
  12 #include <linux/hid.h>
  13 #include <linux/input.h>
  14 #include <linux/module.h>
  15
  16 #include "hid-ids.h"
  17
  18 struct emsff_device {
  19         struct hid_report *report;
  20 };
  21
  22 static int emsff_play(struct input_dev *dev, void *data,
  23                          struct ff_effect *effect)
  24 {
  25         struct hid_device *hid = input_get_drvdata(dev);
  26         struct emsff_device *emsff = data;
  27         int weak, strong;
  28
  29         weak = effect->u.rumble.weak_magnitude;
  30         strong = effect->u.rumble.strong_magnitude;
  31
  32         dbg_hid("called with 0x%04x 0x%04x\n", strong, weak);
  33
  34         weak = weak * 0xff / 0xffff;
  35         strong = strong * 0xff / 0xffff;
  36
  37         emsff->report->field[0]->value[1] = weak;
  38         emsff->report->field[0]->value[2] = strong;
  39
  40         dbg_hid("running with 0x%02x 0x%02x\n", strong, weak);
  41         hid_hw_request(hid, emsff->report, HID_REQ_SET_REPORT);
  42
  43         return 0;
  44 }
  45
  46 static int emsff_init(struct hid_device *hid)
  47 {
  48         struct emsff_device *emsff;
  49         struct hid_report *report;
  50         struct hid_input *hidinput = list_first_entry(&hid->inputs,
  51                                                 struct hid_input, list);
  52         struct list_head *report_list =
  53                         &hid->report_enum[HID_OUTPUT_REPORT].report_list;
  54         struct input_dev *dev = hidinput->input;
  55         int error;
  56
  57         if (list_empty(report_list)) {
  58                 hid_err(hid, "no output reports found\n");
  59                 return -ENODEV;
  60         }
  61
  62         report = list_first_entry(report_list, struct hid_report, list);
  63         if (report->maxfield < 1) {
  64                 hid_err(hid, "no fields in the report\n");
  65                 return -ENODEV;
  66         }
  67
  68         if (report->field[0]->report_count < 7) {
  69                 hid_err(hid, "not enough values in the field\n");
  70                 return -ENODEV;
  71         }
  72
  73         emsff = kzalloc(sizeof(struct emsff_device), GFP_KERNEL);
  74         if (!emsff)
  75                 return -ENOMEM;
  76
  77         set_bit(FF_RUMBLE, dev->ffbit);
  78
  79         error = input_ff_create_memless(dev, emsff, emsff_play);
  80         if (error) {
  81                 kfree(emsff);
  82                 return error;
  83         }
  84
  85         emsff->report = report;
  86         emsff->report->field[0]->value[0] = 0x01;
  87         emsff->report->field[0]->value[1] = 0x00;
  88         emsff->report->field[0]->value[2] = 0x00;
  89         emsff->report->field[0]->value[3] = 0x00;
  90         emsff->report->field[0]->value[4] = 0x00;
  91         emsff->report->field[0]->value[5] = 0x00;
  92         emsff->report->field[0]->value[6] = 0x00;
  93         hid_hw_request(hid, emsff->report, HID_REQ_SET_REPORT);
  94
  95         hid_info(hid, "force feedback for EMS based devices by Ignaz Forster <ignaz.forster@gmx.de>\n");
  96
  97         return 0;
  98 }
  99
 100 static int ems_probe(struct hid_device *hdev, const struct hid_device_id *id)
 101 {
 102         int ret;
 103
 104         ret = hid_parse(hdev);
 105         if (ret) {
 106                 hid_err(hdev, "parse failed\n");
 107                 goto err;
 108         }
 109
 110         ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT & ~HID_CONNECT_FF);
 111         if (ret) {
 112                 hid_err(hdev, "hw start failed\n");
 113                 goto err;
 114         }
 115
 116         ret = emsff_init(hdev);
 117         if (ret) {
 118                 dev_err(&hdev->dev, "force feedback init failed\n");
 119                 hid_hw_stop(hdev);
 120                 goto err;
 121         }
 122
 123         return 0;
 124 err:
 125         return ret;
 126 }
 127
 128 static const struct hid_device_id ems_devices[] = {
 129         { HID_USB_DEVICE(USB_VENDOR_ID_EMS, USB_DEVICE_ID_EMS_TRIO_LINKER_PLUS_II) },
 130         { }
 131 };
 132 MODULE_DEVICE_TABLE(hid, ems_devices);
 133
 134 static struct hid_driver ems_driver = {
 135         .name = "hkems",
 136         .id_table = ems_devices,
 137         .probe = ems_probe,
 138 };
 139 module_hid_driver(ems_driver);
 140
 141 MODULE_LICENSE("GPL");
 142