1  // SPDX-License-Identifier: GPL-2.0-or-later
2  /*
3   * HID driver for PhoenixRC 8-axis flight controller
4   *
5   * Copyright (C) 2022 Marcus Folkesson <marcus.folkesson@gmail.com>
6   */
7  
8  #include <linux/device.h>
9  #include <linux/hid.h>
10  #include <linux/module.h>
11  
12  #include "hid-ids.h"
13  
14  struct pxrc_priv {
15  	u8 slider;
16  	u8 dial;
17  	bool alternate;
18  };
19  
20  static const __u8 pxrc_rdesc_fixed[] = {
21  	0x05, 0x01,        // Usage Page (Generic Desktop Ctrls)
22  	0x09, 0x04,        // Usage (Joystick)
23  	0xA1, 0x01,        // Collection (Application)
24  	0x09, 0x01,        //   Usage (Pointer)
25  	0xA1, 0x00,        //   Collection (Physical)
26  	0x09, 0x30,        //     Usage (X)
27  	0x09, 0x36,        //     Usage (Slider)
28  	0x09, 0x31,        //     Usage (Y)
29  	0x09, 0x32,        //     Usage (Z)
30  	0x09, 0x33,        //     Usage (Rx)
31  	0x09, 0x34,        //     Usage (Ry)
32  	0x09, 0x35,        //     Usage (Rz)
33  	0x09, 0x37,        //     Usage (Dial)
34  	0x15, 0x00,        //     Logical Minimum (0)
35  	0x26, 0xFF, 0x00,  //     Logical Maximum (255)
36  	0x35, 0x00,        //     Physical Minimum (0)
37  	0x46, 0xFF, 0x00,  //     Physical Maximum (255)
38  	0x75, 0x08,        //     Report Size (8)
39  	0x95, 0x08,        //     Report Count (8)
40  	0x81, 0x02,        //     Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position)
41  	0xC0,              //   End Collection
42  	0xC0,              // End Collection
43  };
44  
45  static const __u8 *pxrc_report_fixup(struct hid_device *hdev, __u8 *rdesc,
46  				     unsigned int *rsize)
47  {
48  	hid_info(hdev, "fixing up PXRC report descriptor\n");
49  	*rsize = sizeof(pxrc_rdesc_fixed);
50  	return pxrc_rdesc_fixed;
51  }
52  
53  static int pxrc_raw_event(struct hid_device *hdev, struct hid_report *report,
54  	 u8 *data, int size)
55  {
56  	struct pxrc_priv *priv = hid_get_drvdata(hdev);
57  
58  	if (priv->alternate)
59  		priv->slider = data[7];
60  	else
61  		priv->dial = data[7];
62  
63  	data[1] = priv->slider;
64  	data[7] = priv->dial;
65  
66  	priv->alternate = !priv->alternate;
67  	return 0;
68  }
69  
70  static int pxrc_probe(struct hid_device *hdev, const struct hid_device_id *id)
71  {
72  	int ret;
73  	struct pxrc_priv *priv;
74  
75  	priv = devm_kzalloc(&hdev->dev, sizeof(*priv), GFP_KERNEL);
76  	if (!priv)
77  		return -ENOMEM;
78  	hid_set_drvdata(hdev, priv);
79  
80  	ret = hid_parse(hdev);
81  	if (ret) {
82  		hid_err(hdev, "parse failed\n");
83  		return ret;
84  	}
85  
86  	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
87  	if (ret) {
88  		hid_err(hdev, "hw start failed\n");
89  		return ret;
90  	}
91  
92  	return 0;
93  }
94  
95  static const struct hid_device_id pxrc_devices[] = {
96  	{ HID_USB_DEVICE(USB_VENDOR_ID_MULTIPLE_1781, USB_DEVICE_ID_PHOENIXRC) },
97  	{ /* sentinel */ }
98  };
99  MODULE_DEVICE_TABLE(hid, pxrc_devices);
100  
101  static struct hid_driver pxrc_driver = {
102  	.name = "hid-pxrc",
103  	.id_table = pxrc_devices,
104  	.report_fixup = pxrc_report_fixup,
105  	.probe = pxrc_probe,
106  	.raw_event = pxrc_raw_event,
107  };
108  module_hid_driver(pxrc_driver);
109  
110  MODULE_AUTHOR("Marcus Folkesson <marcus.folkesson@gmail.com>");
111  MODULE_DESCRIPTION("HID driver for PXRC 8-axis flight controller");
112  MODULE_LICENSE("GPL");
113