drivers/hid/hid-letsketch.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Copyright (c) 2021 Hans de Goede <hdegoede@redhat.com>
0004  *
0005  * Driver for the LetSketch / VSON WP9620N drawing tablet.
0006  * This drawing tablet is also sold under other brand names such as Case U,
0007  * presumably this driver will work for all of them. But it has only been
0008  * tested with a LetSketch WP9620N model.
0009  *
0010  * These tablets also work without a special HID driver, but then only part
0011  * of the active area works and both the pad and stylus buttons are hardwired
0012  * to special key-combos. E.g. the 2 stylus buttons send right mouse clicks /
0013  * resp. "e" key presses.
0014  *
0015  * This device has 4 USB interfaces:
0016  *
0017  * Interface 0 EP 0x81 bootclass mouse, rdesc len 18, report id 0x08,
0018  *                                                    Application(ff00.0001)
0019  *  This interface sends raw event input reports in a custom format, but only
0020  *  after doing the special dance from letsketch_probe(). After enabling this
0021  *  interface the other 3 interfaces are disabled.
0022  *
0023  * Interface 1 EP 0x82 bootclass mouse, rdesc len 83, report id 0x0a, Tablet
0024  *  This interface sends absolute events for the pen, including pressure,
0025  *  but only for some part of the active area due to special "aspect ratio"
0026  *  correction and only half by default since it assumes it will be used
0027  *  with a phone in portraid mode, while using the tablet in landscape mode.
0028  *  Also stylus + pad button events are not reported here.
0029  *
0030  * Interface 2 EP 0x83 bootclass keybd, rdesc len 64, report id none, Std Kbd
0031  *  This interfaces send various hard-coded key-combos for the pad buttons
0032  *  and "e" keypresses for the 2nd stylus button
0033  *
0034  * Interface 3 EP 0x84 bootclass mouse, rdesc len 75, report id 0x01, Std Mouse
0035  *  This reports right-click mouse-button events for the 1st stylus button
0036  */
0037 #include <linux/device.h>
0038 #include <linux/input.h>
0039 #include <linux/hid.h>
0040 #include <linux/module.h>
0041 #include <linux/timer.h>
0042 #include <linux/usb.h>
0043
0044 #include <asm/unaligned.h>
0045
0046 #include "hid-ids.h"
0047
0048 #define LETSKETCH_RAW_IF        0
0049
0050 #define LETSKETCH_RAW_DATA_LEN      12
0051 #define LETSKETCH_RAW_REPORT_ID     8
0052
0053 #define LETSKETCH_PAD_BUTTONS       5
0054
0055 #define LETSKETCH_INFO_STR_IDX_BEGIN    0xc8
0056 #define LETSKETCH_INFO_STR_IDX_END  0xca
0057
0058 #define LETSKETCH_GET_STRING_RETRIES    5
0059
0060 struct letsketch_data {
0061     struct hid_device *hdev;
0062     struct input_dev *input_tablet;
0063     struct input_dev *input_tablet_pad;
0064     struct timer_list inrange_timer;
0065 };
0066
0067 static int letsketch_open(struct input_dev *dev)
0068 {
0069     struct letsketch_data *data = input_get_drvdata(dev);
0070
0071     return hid_hw_open(data->hdev);
0072 }
0073
0074 static void letsketch_close(struct input_dev *dev)
0075 {
0076     struct letsketch_data *data = input_get_drvdata(dev);
0077
0078     hid_hw_close(data->hdev);
0079 }
0080
0081 static struct input_dev *letsketch_alloc_input_dev(struct letsketch_data *data)
0082 {
0083     struct input_dev *input;
0084
0085     input = devm_input_allocate_device(&data->hdev->dev);
0086     if (!input)
0087         return NULL;
0088
0089     input->id.bustype = data->hdev->bus;
0090     input->id.vendor  = data->hdev->vendor;
0091     input->id.product = data->hdev->product;
0092     input->id.version = data->hdev->bus;
0093     input->phys = data->hdev->phys;
0094     input->uniq = data->hdev->uniq;
0095     input->open = letsketch_open;
0096     input->close = letsketch_close;
0097
0098     input_set_drvdata(input, data);
0099
0100     return input;
0101 }
0102
0103 static int letsketch_setup_input_tablet(struct letsketch_data *data)
0104 {
0105     struct input_dev *input;
0106
0107     input = letsketch_alloc_input_dev(data);
0108     if (!input)
0109         return -ENOMEM;
0110
0111     input_set_abs_params(input, ABS_X, 0, 50800, 0, 0);
0112     input_set_abs_params(input, ABS_Y, 0, 31750, 0, 0);
0113     input_set_abs_params(input, ABS_PRESSURE, 0, 8192, 0, 0);
0114     input_abs_set_res(input, ABS_X, 240);
0115     input_abs_set_res(input, ABS_Y, 225);
0116     input_set_capability(input, EV_KEY, BTN_TOUCH);
0117     input_set_capability(input, EV_KEY, BTN_TOOL_PEN);
0118     input_set_capability(input, EV_KEY, BTN_STYLUS);
0119     input_set_capability(input, EV_KEY, BTN_STYLUS2);
0120
0121     /* All known brands selling this tablet use WP9620[N] as model name */
0122     input->name = "WP9620 Tablet";
0123
0124     data->input_tablet = input;
0125
0126     return input_register_device(data->input_tablet);
0127 }
0128
0129 static int letsketch_setup_input_tablet_pad(struct letsketch_data *data)
0130 {
0131     struct input_dev *input;
0132     int i;
0133
0134     input = letsketch_alloc_input_dev(data);
0135     if (!input)
0136         return -ENOMEM;
0137
0138     for (i = 0; i < LETSKETCH_PAD_BUTTONS; i++)
0139         input_set_capability(input, EV_KEY, BTN_0 + i);
0140
0141     /*
0142      * These are never send on the pad input_dev, but must be set
0143      * on the Pad to make udev / libwacom happy.
0144      */
0145     input_set_abs_params(input, ABS_X, 0, 1, 0, 0);
0146     input_set_abs_params(input, ABS_Y, 0, 1, 0, 0);
0147     input_set_capability(input, EV_KEY, BTN_STYLUS);
0148
0149     input->name = "WP9620 Pad";
0150
0151     data->input_tablet_pad = input;
0152
0153     return input_register_device(data->input_tablet_pad);
0154 }
0155
0156 static void letsketch_inrange_timeout(struct timer_list *t)
0157 {
0158     struct letsketch_data *data = from_timer(data, t, inrange_timer);
0159     struct input_dev *input = data->input_tablet;
0160
0161     input_report_key(input, BTN_TOOL_PEN, 0);
0162     input_sync(input);
0163 }
0164
0165 static int letsketch_raw_event(struct hid_device *hdev,
0166                    struct hid_report *report,
0167                    u8 *raw_data, int size)
0168 {
0169     struct letsketch_data *data = hid_get_drvdata(hdev);
0170     struct input_dev *input;
0171     int i;
0172
0173     if (size != LETSKETCH_RAW_DATA_LEN || raw_data[0] != LETSKETCH_RAW_REPORT_ID)
0174         return 0;
0175
0176     switch (raw_data[1] & 0xf0) {
0177     case 0x80: /* Pen data */
0178         input = data->input_tablet;
0179         input_report_key(input, BTN_TOOL_PEN, 1);
0180         input_report_key(input, BTN_TOUCH, raw_data[1] & 0x01);
0181         input_report_key(input, BTN_STYLUS, raw_data[1] & 0x02);
0182         input_report_key(input, BTN_STYLUS2, raw_data[1] & 0x04);
0183         input_report_abs(input, ABS_X,
0184                  get_unaligned_le16(raw_data + 2));
0185         input_report_abs(input, ABS_Y,
0186                  get_unaligned_le16(raw_data + 4));
0187         input_report_abs(input, ABS_PRESSURE,
0188                  get_unaligned_le16(raw_data + 6));
0189         /*
0190          * There is no out of range event, so use a timer for this
0191          * when in range we get an event approx. every 8 ms.
0192          */
0193         mod_timer(&data->inrange_timer, jiffies + msecs_to_jiffies(100));
0194         break;
0195     case 0xe0: /* Pad data */
0196         input = data->input_tablet_pad;
0197         for (i = 0; i < LETSKETCH_PAD_BUTTONS; i++)
0198             input_report_key(input, BTN_0 + i, raw_data[4] == (i + 1));
0199         break;
0200     default:
0201         hid_warn(data->hdev, "Warning unknown data header: 0x%02x\n",
0202              raw_data[0]);
0203         return 0;
0204     }
0205
0206     input_sync(input);
0207     return 0;
0208 }
0209
0210 /*
0211  * The tablets magic handshake to put it in raw mode relies on getting
0212  * string descriptors. But the firmware is buggy and does not like it if
0213  * we do this too fast. Even if we go slow sometimes the usb_string() call
0214  * fails. Ignore errors and retry it a couple of times if necessary.
0215  */
0216 static int letsketch_get_string(struct usb_device *udev, int index, char *buf, int size)
0217 {
0218     int i, ret;
0219
0220     for (i = 0; i < LETSKETCH_GET_STRING_RETRIES; i++) {
0221         usleep_range(5000, 7000);
0222         ret = usb_string(udev, index, buf, size);
0223         if (ret > 0)
0224             return 0;
0225     }
0226
0227     dev_err(&udev->dev, "Max retries (%d) exceeded reading string descriptor %d\n",
0228         LETSKETCH_GET_STRING_RETRIES, index);
0229     return ret ? ret : -EIO;
0230 }
0231
0232 static int letsketch_probe(struct hid_device *hdev, const struct hid_device_id *id)
0233 {
0234     struct device *dev = &hdev->dev;
0235     struct letsketch_data *data;
0236     struct usb_interface *intf;
0237     struct usb_device *udev;
0238     char buf[256];
0239     int i, ret;
0240
0241     if (!hid_is_using_ll_driver(hdev, &usb_hid_driver))
0242         return -ENODEV;
0243
0244     intf = to_usb_interface(hdev->dev.parent);
0245     if (intf->altsetting->desc.bInterfaceNumber != LETSKETCH_RAW_IF)
0246         return -ENODEV; /* Ignore the other interfaces */
0247
0248     udev = interface_to_usbdev(intf);
0249
0250     /*
0251      * Instead of using a set-feature request, or even a custom USB ctrl
0252      * message the tablet needs this elaborate magic reading of USB
0253      * string descriptors to kick it into raw mode. This is what the
0254      * Windows drivers are seen doing in an USB trace under Windows.
0255      */
0256     for (i = LETSKETCH_INFO_STR_IDX_BEGIN; i <= LETSKETCH_INFO_STR_IDX_END; i++) {
0257         ret = letsketch_get_string(udev, i, buf, sizeof(buf));
0258         if (ret)
0259             return ret;
0260
0261         hid_info(hdev, "Device info: %s\n", buf);
0262     }
0263
0264     for (i = 1; i <= 250; i++) {
0265         ret = letsketch_get_string(udev, i, buf, sizeof(buf));
0266         if (ret)
0267             return ret;
0268     }
0269
0270     ret = letsketch_get_string(udev, 0x64, buf, sizeof(buf));
0271     if (ret)
0272         return ret;
0273
0274     ret = letsketch_get_string(udev, LETSKETCH_INFO_STR_IDX_BEGIN, buf, sizeof(buf));
0275     if (ret)
0276         return ret;
0277
0278     /*
0279      * The tablet should be in raw mode now, end with a final delay before
0280      * doing further IO to the device.
0281      */
0282     usleep_range(5000, 7000);
0283
0284     ret = hid_parse(hdev);
0285     if (ret)
0286         return ret;
0287
0288     data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
0289     if (!data)
0290         return -ENOMEM;
0291
0292     data->hdev = hdev;
0293     timer_setup(&data->inrange_timer, letsketch_inrange_timeout, 0);
0294     hid_set_drvdata(hdev, data);
0295
0296     ret = letsketch_setup_input_tablet(data);
0297     if (ret)
0298         return ret;
0299
0300     ret = letsketch_setup_input_tablet_pad(data);
0301     if (ret)
0302         return ret;
0303
0304     return hid_hw_start(hdev, HID_CONNECT_HIDRAW);
0305 }
0306
0307 static const struct hid_device_id letsketch_devices[] = {
0308     { HID_USB_DEVICE(USB_VENDOR_ID_LETSKETCH, USB_DEVICE_ID_WP9620N) },
0309     { }
0310 };
0311 MODULE_DEVICE_TABLE(hid, letsketch_devices);
0312
0313 static struct hid_driver letsketch_driver = {
0314     .name = "letsketch",
0315     .id_table = letsketch_devices,
0316     .probe = letsketch_probe,
0317     .raw_event = letsketch_raw_event,
0318 };
0319 module_hid_driver(letsketch_driver);
0320
0321 MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
0322 MODULE_LICENSE("GPL");