1// SPDX-License-Identifier: GPL-2.0
2/*
3 * HID support for Vivaldi Keyboard
4 *
5 * Copyright 2020 Google LLC.
6 * Author: Sean O'Brien <seobrien@chromium.org>
7 */
8
9#include <linux/hid.h>
10#include <linux/module.h>
11
12#define MIN_FN_ROW_KEY	1
13#define MAX_FN_ROW_KEY	24
14#define HID_VD_FN_ROW_PHYSMAP 0x00000001
15#define HID_USAGE_FN_ROW_PHYSMAP (HID_UP_GOOGLEVENDOR | HID_VD_FN_ROW_PHYSMAP)
16
17static struct hid_driver hid_vivaldi;
18
19struct vivaldi_data {
20	u32 function_row_physmap[MAX_FN_ROW_KEY - MIN_FN_ROW_KEY + 1];
21	int max_function_row_key;
22};
23
24static ssize_t function_row_physmap_show(struct device *dev,
25					 struct device_attribute *attr,
26					 char *buf)
27{
28	struct hid_device *hdev = to_hid_device(dev);
29	struct vivaldi_data *drvdata = hid_get_drvdata(hdev);
30	ssize_t size = 0;
31	int i;
32
33	if (!drvdata->max_function_row_key)
34		return 0;
35
36	for (i = 0; i < drvdata->max_function_row_key; i++)
37		size += sprintf(buf + size, "%02X ",
38				drvdata->function_row_physmap[i]);
39	size += sprintf(buf + size, "\n");
40	return size;
41}
42
43DEVICE_ATTR_RO(function_row_physmap);
44static struct attribute *sysfs_attrs[] = {
45	&dev_attr_function_row_physmap.attr,
46	NULL
47};
48
49static const struct attribute_group input_attribute_group = {
50	.attrs = sysfs_attrs
51};
52
53static int vivaldi_probe(struct hid_device *hdev,
54			 const struct hid_device_id *id)
55{
56	struct vivaldi_data *drvdata;
57	int ret;
58
59	drvdata = devm_kzalloc(&hdev->dev, sizeof(*drvdata), GFP_KERNEL);
60	if (!drvdata)
61		return -ENOMEM;
62
63	hid_set_drvdata(hdev, drvdata);
64
65	ret = hid_parse(hdev);
66	if (ret)
67		return ret;
68
69	return hid_hw_start(hdev, HID_CONNECT_DEFAULT);
70}
71
72static void vivaldi_feature_mapping(struct hid_device *hdev,
73				    struct hid_field *field,
74				    struct hid_usage *usage)
75{
76	struct vivaldi_data *drvdata = hid_get_drvdata(hdev);
77	struct hid_report *report = field->report;
78	int fn_key;
79	int ret;
80	u32 report_len;
81	u8 *report_data, *buf;
82
83	if (field->logical != HID_USAGE_FN_ROW_PHYSMAP ||
84	    (usage->hid & HID_USAGE_PAGE) != HID_UP_ORDINAL)
85		return;
86
87	fn_key = (usage->hid & HID_USAGE);
88	if (fn_key < MIN_FN_ROW_KEY || fn_key > MAX_FN_ROW_KEY)
89		return;
90	if (fn_key > drvdata->max_function_row_key)
91		drvdata->max_function_row_key = fn_key;
92
93	report_data = buf = hid_alloc_report_buf(report, GFP_KERNEL);
94	if (!report_data)
95		return;
96
97	report_len = hid_report_len(report);
98	if (!report->id) {
99		/*
100		 * hid_hw_raw_request() will stuff report ID (which will be 0)
101		 * into the first byte of the buffer even for unnumbered
102		 * reports, so we need to account for this to avoid getting
103		 * -EOVERFLOW in return.
104		 * Note that hid_alloc_report_buf() adds 7 bytes to the size
105		 * so we can safely say that we have space for an extra byte.
106		 */
107		report_len++;
108	}
109
110	ret = hid_hw_raw_request(hdev, report->id, report_data,
111				 report_len, HID_FEATURE_REPORT,
112				 HID_REQ_GET_REPORT);
113	if (ret < 0) {
114		dev_warn(&hdev->dev, "failed to fetch feature %d\n",
115			 field->report->id);
116		goto out;
117	}
118
119	if (!report->id) {
120		/*
121		 * Undo the damage from hid_hw_raw_request() for unnumbered
122		 * reports.
123		 */
124		report_data++;
125		report_len--;
126	}
127
128	ret = hid_report_raw_event(hdev, HID_FEATURE_REPORT, report_data,
129				   report_len, 0);
130	if (ret) {
131		dev_warn(&hdev->dev, "failed to report feature %d\n",
132			 field->report->id);
133		goto out;
134	}
135
136	drvdata->function_row_physmap[fn_key - MIN_FN_ROW_KEY] =
137	    field->value[usage->usage_index];
138
139out:
140	kfree(buf);
141}
142
143static int vivaldi_input_configured(struct hid_device *hdev,
144				    struct hid_input *hidinput)
145{
146	return devm_device_add_group(&hdev->dev, &input_attribute_group);
147}
148
149static const struct hid_device_id vivaldi_table[] = {
150	{ HID_DEVICE(HID_BUS_ANY, HID_GROUP_VIVALDI, HID_ANY_ID,
151		     HID_ANY_ID) },
152	{ }
153};
154
155MODULE_DEVICE_TABLE(hid, vivaldi_table);
156
157static struct hid_driver hid_vivaldi = {
158	.name = "hid-vivaldi",
159	.id_table = vivaldi_table,
160	.probe = vivaldi_probe,
161	.feature_mapping = vivaldi_feature_mapping,
162	.input_configured = vivaldi_input_configured,
163};
164
165module_hid_driver(hid_vivaldi);
166
167MODULE_AUTHOR("Sean O'Brien");
168MODULE_DESCRIPTION("HID vivaldi driver");
169MODULE_LICENSE("GPL");
170