drivers/hid/hid-letsketch.c

   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
  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 = 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
 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  */
 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
 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");