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 <linux/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 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 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 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 } 102 103 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 } 128 129 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 } 155 156 static void letsketch_inrange_timeout(struct timer_list *t) 157 { 158 struct letsketch_data *data = timer_container_of(data, t, 159 inrange_timer); 160 struct input_dev *input = data->input_tablet; 161 162 input_report_key(input, BTN_TOOL_PEN, 0); 163 input_sync(input); 164 } 165 166 static int letsketch_raw_event(struct hid_device *hdev, 167 struct hid_report *report, 168 u8 *raw_data, int size) 169 { 170 struct letsketch_data *data = hid_get_drvdata(hdev); 171 struct input_dev *input; 172 int i; 173 174 if (size != LETSKETCH_RAW_DATA_LEN || raw_data[0] != LETSKETCH_RAW_REPORT_ID) 175 return 0; 176 177 switch (raw_data[1] & 0xf0) { 178 case 0x80: /* Pen data */ 179 input = data->input_tablet; 180 input_report_key(input, BTN_TOOL_PEN, 1); 181 input_report_key(input, BTN_TOUCH, raw_data[1] & 0x01); 182 input_report_key(input, BTN_STYLUS, raw_data[1] & 0x02); 183 input_report_key(input, BTN_STYLUS2, raw_data[1] & 0x04); 184 input_report_abs(input, ABS_X, 185 get_unaligned_le16(raw_data + 2)); 186 input_report_abs(input, ABS_Y, 187 get_unaligned_le16(raw_data + 4)); 188 input_report_abs(input, ABS_PRESSURE, 189 get_unaligned_le16(raw_data + 6)); 190 /* 191 * There is no out of range event, so use a timer for this 192 * when in range we get an event approx. every 8 ms. 193 */ 194 mod_timer(&data->inrange_timer, jiffies + msecs_to_jiffies(100)); 195 break; 196 case 0xe0: /* Pad data */ 197 input = data->input_tablet_pad; 198 for (i = 0; i < LETSKETCH_PAD_BUTTONS; i++) 199 input_report_key(input, BTN_0 + i, raw_data[4] == (i + 1)); 200 break; 201 default: 202 hid_warn(data->hdev, "Warning unknown data header: 0x%02x\n", 203 raw_data[0]); 204 return 0; 205 } 206 207 input_sync(input); 208 return 0; 209 } 210 211 /* 212 * The tablets magic handshake to put it in raw mode relies on getting 213 * string descriptors. But the firmware is buggy and does not like it if 214 * we do this too fast. Even if we go slow sometimes the usb_string() call 215 * fails. Ignore errors and retry it a couple of times if necessary. 216 */ 217 static int letsketch_get_string(struct usb_device *udev, int index, char *buf, int size) 218 { 219 int i, ret; 220 221 for (i = 0; i < LETSKETCH_GET_STRING_RETRIES; i++) { 222 usleep_range(5000, 7000); 223 ret = usb_string(udev, index, buf, size); 224 if (ret > 0) 225 return 0; 226 } 227 228 dev_err(&udev->dev, "Max retries (%d) exceeded reading string descriptor %d\n", 229 LETSKETCH_GET_STRING_RETRIES, index); 230 return ret ? ret : -EIO; 231 } 232 233 static int letsketch_probe(struct hid_device *hdev, const struct hid_device_id *id) 234 { 235 struct device *dev = &hdev->dev; 236 struct letsketch_data *data; 237 struct usb_interface *intf; 238 struct usb_device *udev; 239 char buf[256]; 240 int i, ret; 241 242 if (!hid_is_usb(hdev)) 243 return -ENODEV; 244 245 intf = to_usb_interface(hdev->dev.parent); 246 if (intf->altsetting->desc.bInterfaceNumber != LETSKETCH_RAW_IF) 247 return -ENODEV; /* Ignore the other interfaces */ 248 249 udev = interface_to_usbdev(intf); 250 251 /* 252 * Instead of using a set-feature request, or even a custom USB ctrl 253 * message the tablet needs this elaborate magic reading of USB 254 * string descriptors to kick it into raw mode. This is what the 255 * Windows drivers are seen doing in an USB trace under Windows. 256 */ 257 for (i = LETSKETCH_INFO_STR_IDX_BEGIN; i <= LETSKETCH_INFO_STR_IDX_END; i++) { 258 ret = letsketch_get_string(udev, i, buf, sizeof(buf)); 259 if (ret) 260 return ret; 261 262 hid_info(hdev, "Device info: %s\n", buf); 263 } 264 265 for (i = 1; i <= 250; i++) { 266 ret = letsketch_get_string(udev, i, buf, sizeof(buf)); 267 if (ret) 268 return ret; 269 } 270 271 ret = letsketch_get_string(udev, 0x64, buf, sizeof(buf)); 272 if (ret) 273 return ret; 274 275 ret = letsketch_get_string(udev, LETSKETCH_INFO_STR_IDX_BEGIN, buf, sizeof(buf)); 276 if (ret) 277 return ret; 278 279 /* 280 * The tablet should be in raw mode now, end with a final delay before 281 * doing further IO to the device. 282 */ 283 usleep_range(5000, 7000); 284 285 ret = hid_parse(hdev); 286 if (ret) 287 return ret; 288 289 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); 290 if (!data) 291 return -ENOMEM; 292 293 data->hdev = hdev; 294 timer_setup(&data->inrange_timer, letsketch_inrange_timeout, 0); 295 hid_set_drvdata(hdev, data); 296 297 ret = letsketch_setup_input_tablet(data); 298 if (ret) 299 return ret; 300 301 ret = letsketch_setup_input_tablet_pad(data); 302 if (ret) 303 return ret; 304 305 return hid_hw_start(hdev, HID_CONNECT_HIDRAW); 306 } 307 308 static const struct hid_device_id letsketch_devices[] = { 309 { HID_USB_DEVICE(USB_VENDOR_ID_LETSKETCH, USB_DEVICE_ID_WP9620N) }, 310 { } 311 }; 312 MODULE_DEVICE_TABLE(hid, letsketch_devices); 313 314 static struct hid_driver letsketch_driver = { 315 .name = "letsketch", 316 .id_table = letsketch_devices, 317 .probe = letsketch_probe, 318 .raw_event = letsketch_raw_event, 319 }; 320 module_hid_driver(letsketch_driver); 321 322 MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>"); 323 MODULE_DESCRIPTION("Driver for the LetSketch / VSON WP9620N drawing tablet"); 324 MODULE_LICENSE("GPL"); 325