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1// SPDX-License-Identifier: GPL-2.0-only2/*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 been8 * tested with a LetSketch WP9620N model.9 *10 * These tablets also work without a special HID driver, but then only part11 * of the active area works and both the pad and stylus buttons are hardwired12 * 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 only20 * after doing the special dance from letsketch_probe(). After enabling this21 * interface the other 3 interfaces are disabled.22 *23 * Interface 1 EP 0x82 bootclass mouse, rdesc len 83, report id 0x0a, Tablet24 * 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 used27 * 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 Kbd31 * This interfaces send various hard-coded key-combos for the pad buttons32 * and "e" keypresses for the 2nd stylus button33 *34 * Interface 3 EP 0x84 bootclass mouse, rdesc len 75, report id 0x01, Std Mouse35 * This reports right-click mouse-button events for the 1st stylus button36 */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 <linux/unaligned.h>45 46#include "hid-ids.h"47 48#define LETSKETCH_RAW_IF 049 50#define LETSKETCH_RAW_DATA_LEN 1251#define LETSKETCH_RAW_REPORT_ID 852 53#define LETSKETCH_PAD_BUTTONS 554 55#define LETSKETCH_INFO_STR_IDX_BEGIN 0xc856#define LETSKETCH_INFO_STR_IDX_END 0xca57 58#define LETSKETCH_GET_STRING_RETRIES 559 60struct 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 67static 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 74static 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 81static 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 103static 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 129static 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 set143 * 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 156static 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 165static 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 this191 * 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 getting212 * string descriptors. But the firmware is buggy and does not like it if213 * we do this too fast. Even if we go slow sometimes the usb_string() call214 * fails. Ignore errors and retry it a couple of times if necessary.215 */216static 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 232static 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 ctrl252 * message the tablet needs this elaborate magic reading of USB253 * string descriptors to kick it into raw mode. This is what the254 * 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 before280 * 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 307static const struct hid_device_id letsketch_devices[] = {308 { HID_USB_DEVICE(USB_VENDOR_ID_LETSKETCH, USB_DEVICE_ID_WP9620N) },309 { }310};311MODULE_DEVICE_TABLE(hid, letsketch_devices);312 313static struct hid_driver letsketch_driver = {314 .name = "letsketch",315 .id_table = letsketch_devices,316 .probe = letsketch_probe,317 .raw_event = letsketch_raw_event,318};319module_hid_driver(letsketch_driver);320 321MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");322MODULE_DESCRIPTION("Driver for the LetSketch / VSON WP9620N drawing tablet");323MODULE_LICENSE("GPL");324