1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (c) 2021 Hans de Goede <hdegoede@redhat.com>
4 *
5 * Driver for the LetSketch / VSON WP9620N drawing tablet.
6 * This drawing tablet is also sold under other brand names such as Case U,
7 * presumably this driver will work for all of them. But it has only been
8 * tested with a LetSketch WP9620N model.
9 *
10 * These tablets also work without a special HID driver, but then only part
11 * of the active area works and both the pad and stylus buttons are hardwired
12 * to special key-combos. E.g. the 2 stylus buttons send right mouse clicks /
13 * resp. "e" key presses.
14 *
15 * This device has 4 USB interfaces:
16 *
17 * Interface 0 EP 0x81 bootclass mouse, rdesc len 18, report id 0x08,
18 * Application(ff00.0001)
19 * This interface sends raw event input reports in a custom format, but only
20 * after doing the special dance from letsketch_probe(). After enabling this
21 * interface the other 3 interfaces are disabled.
22 *
23 * Interface 1 EP 0x82 bootclass mouse, rdesc len 83, report id 0x0a, Tablet
24 * This interface sends absolute events for the pen, including pressure,
25 * but only for some part of the active area due to special "aspect ratio"
26 * correction and only half by default since it assumes it will be used
27 * with a phone in portraid mode, while using the tablet in landscape mode.
28 * Also stylus + pad button events are not reported here.
29 *
30 * Interface 2 EP 0x83 bootclass keybd, rdesc len 64, report id none, Std Kbd
31 * This interfaces send various hard-coded key-combos for the pad buttons
32 * and "e" keypresses for the 2nd stylus button
33 *
34 * Interface 3 EP 0x84 bootclass mouse, rdesc len 75, report id 0x01, Std Mouse
35 * This reports right-click mouse-button events for the 1st stylus button
36 */
37 #include <linux/device.h>
38 #include <linux/input.h>
39 #include <linux/hid.h>
40 #include <linux/module.h>
41 #include <linux/timer.h>
42 #include <linux/usb.h>
43
44 #include <asm/unaligned.h>
45
46 #include "hid-ids.h"
47
48 #define LETSKETCH_RAW_IF 0
49
50 #define LETSKETCH_RAW_DATA_LEN 12
51 #define LETSKETCH_RAW_REPORT_ID 8
52
53 #define LETSKETCH_PAD_BUTTONS 5
54
55 #define LETSKETCH_INFO_STR_IDX_BEGIN 0xc8
56 #define LETSKETCH_INFO_STR_IDX_END 0xca
57
58 #define LETSKETCH_GET_STRING_RETRIES 5
59
60 struct letsketch_data {
61 struct hid_device *hdev;
62 struct input_dev *input_tablet;
63 struct input_dev *input_tablet_pad;
64 struct timer_list inrange_timer;
65 };
66
letsketch_open(struct input_dev * dev)67 static int letsketch_open(struct input_dev *dev)
68 {
69 struct letsketch_data *data = input_get_drvdata(dev);
70
71 return hid_hw_open(data->hdev);
72 }
73
letsketch_close(struct input_dev * dev)74 static void letsketch_close(struct input_dev *dev)
75 {
76 struct letsketch_data *data = input_get_drvdata(dev);
77
78 hid_hw_close(data->hdev);
79 }
80
letsketch_alloc_input_dev(struct letsketch_data * data)81 static struct input_dev *letsketch_alloc_input_dev(struct letsketch_data *data)
82 {
83 struct input_dev *input;
84
85 input = devm_input_allocate_device(&data->hdev->dev);
86 if (!input)
87 return NULL;
88
89 input->id.bustype = data->hdev->bus;
90 input->id.vendor = data->hdev->vendor;
91 input->id.product = data->hdev->product;
92 input->id.version = data->hdev->bus;
93 input->phys = data->hdev->phys;
94 input->uniq = data->hdev->uniq;
95 input->open = letsketch_open;
96 input->close = letsketch_close;
97
98 input_set_drvdata(input, data);
99
100 return input;
101 }
102
letsketch_setup_input_tablet(struct letsketch_data * data)103 static int letsketch_setup_input_tablet(struct letsketch_data *data)
104 {
105 struct input_dev *input;
106
107 input = letsketch_alloc_input_dev(data);
108 if (!input)
109 return -ENOMEM;
110
111 input_set_abs_params(input, ABS_X, 0, 50800, 0, 0);
112 input_set_abs_params(input, ABS_Y, 0, 31750, 0, 0);
113 input_set_abs_params(input, ABS_PRESSURE, 0, 8192, 0, 0);
114 input_abs_set_res(input, ABS_X, 240);
115 input_abs_set_res(input, ABS_Y, 225);
116 input_set_capability(input, EV_KEY, BTN_TOUCH);
117 input_set_capability(input, EV_KEY, BTN_TOOL_PEN);
118 input_set_capability(input, EV_KEY, BTN_STYLUS);
119 input_set_capability(input, EV_KEY, BTN_STYLUS2);
120
121 /* All known brands selling this tablet use WP9620[N] as model name */
122 input->name = "WP9620 Tablet";
123
124 data->input_tablet = input;
125
126 return input_register_device(data->input_tablet);
127 }
128
letsketch_setup_input_tablet_pad(struct letsketch_data * data)129 static int letsketch_setup_input_tablet_pad(struct letsketch_data *data)
130 {
131 struct input_dev *input;
132 int i;
133
134 input = letsketch_alloc_input_dev(data);
135 if (!input)
136 return -ENOMEM;
137
138 for (i = 0; i < LETSKETCH_PAD_BUTTONS; i++)
139 input_set_capability(input, EV_KEY, BTN_0 + i);
140
141 /*
142 * These are never send on the pad input_dev, but must be set
143 * on the Pad to make udev / libwacom happy.
144 */
145 input_set_abs_params(input, ABS_X, 0, 1, 0, 0);
146 input_set_abs_params(input, ABS_Y, 0, 1, 0, 0);
147 input_set_capability(input, EV_KEY, BTN_STYLUS);
148
149 input->name = "WP9620 Pad";
150
151 data->input_tablet_pad = input;
152
153 return input_register_device(data->input_tablet_pad);
154 }
155
letsketch_inrange_timeout(struct timer_list * t)156 static void letsketch_inrange_timeout(struct timer_list *t)
157 {
158 struct letsketch_data *data = from_timer(data, t, inrange_timer);
159 struct input_dev *input = data->input_tablet;
160
161 input_report_key(input, BTN_TOOL_PEN, 0);
162 input_sync(input);
163 }
164
letsketch_raw_event(struct hid_device * hdev,struct hid_report * report,u8 * raw_data,int size)165 static int letsketch_raw_event(struct hid_device *hdev,
166 struct hid_report *report,
167 u8 *raw_data, int size)
168 {
169 struct letsketch_data *data = hid_get_drvdata(hdev);
170 struct input_dev *input;
171 int i;
172
173 if (size != LETSKETCH_RAW_DATA_LEN || raw_data[0] != LETSKETCH_RAW_REPORT_ID)
174 return 0;
175
176 switch (raw_data[1] & 0xf0) {
177 case 0x80: /* Pen data */
178 input = data->input_tablet;
179 input_report_key(input, BTN_TOOL_PEN, 1);
180 input_report_key(input, BTN_TOUCH, raw_data[1] & 0x01);
181 input_report_key(input, BTN_STYLUS, raw_data[1] & 0x02);
182 input_report_key(input, BTN_STYLUS2, raw_data[1] & 0x04);
183 input_report_abs(input, ABS_X,
184 get_unaligned_le16(raw_data + 2));
185 input_report_abs(input, ABS_Y,
186 get_unaligned_le16(raw_data + 4));
187 input_report_abs(input, ABS_PRESSURE,
188 get_unaligned_le16(raw_data + 6));
189 /*
190 * There is no out of range event, so use a timer for this
191 * when in range we get an event approx. every 8 ms.
192 */
193 mod_timer(&data->inrange_timer, jiffies + msecs_to_jiffies(100));
194 break;
195 case 0xe0: /* Pad data */
196 input = data->input_tablet_pad;
197 for (i = 0; i < LETSKETCH_PAD_BUTTONS; i++)
198 input_report_key(input, BTN_0 + i, raw_data[4] == (i + 1));
199 break;
200 default:
201 hid_warn(data->hdev, "Warning unknown data header: 0x%02x\n",
202 raw_data[0]);
203 return 0;
204 }
205
206 input_sync(input);
207 return 0;
208 }
209
210 /*
211 * The tablets magic handshake to put it in raw mode relies on getting
212 * string descriptors. But the firmware is buggy and does not like it if
213 * we do this too fast. Even if we go slow sometimes the usb_string() call
214 * fails. Ignore errors and retry it a couple of times if necessary.
215 */
letsketch_get_string(struct usb_device * udev,int index,char * buf,int size)216 static int letsketch_get_string(struct usb_device *udev, int index, char *buf, int size)
217 {
218 int i, ret;
219
220 for (i = 0; i < LETSKETCH_GET_STRING_RETRIES; i++) {
221 usleep_range(5000, 7000);
222 ret = usb_string(udev, index, buf, size);
223 if (ret > 0)
224 return 0;
225 }
226
227 dev_err(&udev->dev, "Max retries (%d) exceeded reading string descriptor %d\n",
228 LETSKETCH_GET_STRING_RETRIES, index);
229 return ret ? ret : -EIO;
230 }
231
letsketch_probe(struct hid_device * hdev,const struct hid_device_id * id)232 static int letsketch_probe(struct hid_device *hdev, const struct hid_device_id *id)
233 {
234 struct device *dev = &hdev->dev;
235 struct letsketch_data *data;
236 struct usb_interface *intf;
237 struct usb_device *udev;
238 char buf[256];
239 int i, ret;
240
241 if (!hid_is_usb(hdev))
242 return -ENODEV;
243
244 intf = to_usb_interface(hdev->dev.parent);
245 if (intf->altsetting->desc.bInterfaceNumber != LETSKETCH_RAW_IF)
246 return -ENODEV; /* Ignore the other interfaces */
247
248 udev = interface_to_usbdev(intf);
249
250 /*
251 * Instead of using a set-feature request, or even a custom USB ctrl
252 * message the tablet needs this elaborate magic reading of USB
253 * string descriptors to kick it into raw mode. This is what the
254 * Windows drivers are seen doing in an USB trace under Windows.
255 */
256 for (i = LETSKETCH_INFO_STR_IDX_BEGIN; i <= LETSKETCH_INFO_STR_IDX_END; i++) {
257 ret = letsketch_get_string(udev, i, buf, sizeof(buf));
258 if (ret)
259 return ret;
260
261 hid_info(hdev, "Device info: %s\n", buf);
262 }
263
264 for (i = 1; i <= 250; i++) {
265 ret = letsketch_get_string(udev, i, buf, sizeof(buf));
266 if (ret)
267 return ret;
268 }
269
270 ret = letsketch_get_string(udev, 0x64, buf, sizeof(buf));
271 if (ret)
272 return ret;
273
274 ret = letsketch_get_string(udev, LETSKETCH_INFO_STR_IDX_BEGIN, buf, sizeof(buf));
275 if (ret)
276 return ret;
277
278 /*
279 * The tablet should be in raw mode now, end with a final delay before
280 * doing further IO to the device.
281 */
282 usleep_range(5000, 7000);
283
284 ret = hid_parse(hdev);
285 if (ret)
286 return ret;
287
288 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
289 if (!data)
290 return -ENOMEM;
291
292 data->hdev = hdev;
293 timer_setup(&data->inrange_timer, letsketch_inrange_timeout, 0);
294 hid_set_drvdata(hdev, data);
295
296 ret = letsketch_setup_input_tablet(data);
297 if (ret)
298 return ret;
299
300 ret = letsketch_setup_input_tablet_pad(data);
301 if (ret)
302 return ret;
303
304 return hid_hw_start(hdev, HID_CONNECT_HIDRAW);
305 }
306
307 static const struct hid_device_id letsketch_devices[] = {
308 { HID_USB_DEVICE(USB_VENDOR_ID_LETSKETCH, USB_DEVICE_ID_WP9620N) },
309 { }
310 };
311 MODULE_DEVICE_TABLE(hid, letsketch_devices);
312
313 static struct hid_driver letsketch_driver = {
314 .name = "letsketch",
315 .id_table = letsketch_devices,
316 .probe = letsketch_probe,
317 .raw_event = letsketch_raw_event,
318 };
319 module_hid_driver(letsketch_driver);
320
321 MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
322 MODULE_LICENSE("GPL");
323
