// SPDX-License-Identifier: GPL-2.0-only /* * Copyright (c) 2021 Hans de Goede * * Driver for the LetSketch / VSON WP9620N drawing tablet. * This drawing tablet is also sold under other brand names such as Case U, * presumably this driver will work for all of them. But it has only been * tested with a LetSketch WP9620N model. * * These tablets also work without a special HID driver, but then only part * of the active area works and both the pad and stylus buttons are hardwired * to special key-combos. E.g. the 2 stylus buttons send right mouse clicks / * resp. "e" key presses. * * This device has 4 USB interfaces: * * Interface 0 EP 0x81 bootclass mouse, rdesc len 18, report id 0x08, * Application(ff00.0001) * This interface sends raw event input reports in a custom format, but only * after doing the special dance from letsketch_probe(). After enabling this * interface the other 3 interfaces are disabled. * * Interface 1 EP 0x82 bootclass mouse, rdesc len 83, report id 0x0a, Tablet * This interface sends absolute events for the pen, including pressure, * but only for some part of the active area due to special "aspect ratio" * correction and only half by default since it assumes it will be used * with a phone in portraid mode, while using the tablet in landscape mode. * Also stylus + pad button events are not reported here. * * Interface 2 EP 0x83 bootclass keybd, rdesc len 64, report id none, Std Kbd * This interfaces send various hard-coded key-combos for the pad buttons * and "e" keypresses for the 2nd stylus button * * Interface 3 EP 0x84 bootclass mouse, rdesc len 75, report id 0x01, Std Mouse * This reports right-click mouse-button events for the 1st stylus button */ #include #include #include #include #include #include #include #include "hid-ids.h" #define LETSKETCH_RAW_IF 0 #define LETSKETCH_RAW_DATA_LEN 12 #define LETSKETCH_RAW_REPORT_ID 8 #define LETSKETCH_PAD_BUTTONS 5 #define LETSKETCH_INFO_STR_IDX_BEGIN 0xc8 #define LETSKETCH_INFO_STR_IDX_END 0xca #define LETSKETCH_GET_STRING_RETRIES 5 struct letsketch_data { struct hid_device *hdev; struct input_dev *input_tablet; struct input_dev *input_tablet_pad; struct timer_list inrange_timer; }; static int letsketch_open(struct input_dev *dev) { struct letsketch_data *data = input_get_drvdata(dev); return hid_hw_open(data->hdev); } static void letsketch_close(struct input_dev *dev) { struct letsketch_data *data = input_get_drvdata(dev); hid_hw_close(data->hdev); } static struct input_dev *letsketch_alloc_input_dev(struct letsketch_data *data) { struct input_dev *input; input = devm_input_allocate_device(&data->hdev->dev); if (!input) return NULL; input->id.bustype = data->hdev->bus; input->id.vendor = data->hdev->vendor; input->id.product = data->hdev->product; input->id.version = data->hdev->bus; input->phys = data->hdev->phys; input->uniq = data->hdev->uniq; input->open = letsketch_open; input->close = letsketch_close; input_set_drvdata(input, data); return input; } static int letsketch_setup_input_tablet(struct letsketch_data *data) { struct input_dev *input; input = letsketch_alloc_input_dev(data); if (!input) return -ENOMEM; input_set_abs_params(input, ABS_X, 0, 50800, 0, 0); input_set_abs_params(input, ABS_Y, 0, 31750, 0, 0); input_set_abs_params(input, ABS_PRESSURE, 0, 8192, 0, 0); input_abs_set_res(input, ABS_X, 240); input_abs_set_res(input, ABS_Y, 225); input_set_capability(input, EV_KEY, BTN_TOUCH); input_set_capability(input, EV_KEY, BTN_TOOL_PEN); input_set_capability(input, EV_KEY, BTN_STYLUS); input_set_capability(input, EV_KEY, BTN_STYLUS2); /* All known brands selling this tablet use WP9620[N] as model name */ input->name = "WP9620 Tablet"; data->input_tablet = input; return input_register_device(data->input_tablet); } static int letsketch_setup_input_tablet_pad(struct letsketch_data *data) { struct input_dev *input; int i; input = letsketch_alloc_input_dev(data); if (!input) return -ENOMEM; for (i = 0; i < LETSKETCH_PAD_BUTTONS; i++) input_set_capability(input, EV_KEY, BTN_0 + i); /* * These are never send on the pad input_dev, but must be set * on the Pad to make udev / libwacom happy. */ input_set_abs_params(input, ABS_X, 0, 1, 0, 0); input_set_abs_params(input, ABS_Y, 0, 1, 0, 0); input_set_capability(input, EV_KEY, BTN_STYLUS); input->name = "WP9620 Pad"; data->input_tablet_pad = input; return input_register_device(data->input_tablet_pad); } static void letsketch_inrange_timeout(struct timer_list *t) { struct letsketch_data *data = from_timer(data, t, inrange_timer); struct input_dev *input = data->input_tablet; input_report_key(input, BTN_TOOL_PEN, 0); input_sync(input); } static int letsketch_raw_event(struct hid_device *hdev, struct hid_report *report, u8 *raw_data, int size) { struct letsketch_data *data = hid_get_drvdata(hdev); struct input_dev *input; int i; if (size != LETSKETCH_RAW_DATA_LEN || raw_data[0] != LETSKETCH_RAW_REPORT_ID) return 0; switch (raw_data[1] & 0xf0) { case 0x80: /* Pen data */ input = data->input_tablet; input_report_key(input, BTN_TOOL_PEN, 1); input_report_key(input, BTN_TOUCH, raw_data[1] & 0x01); input_report_key(input, BTN_STYLUS, raw_data[1] & 0x02); input_report_key(input, BTN_STYLUS2, raw_data[1] & 0x04); input_report_abs(input, ABS_X, get_unaligned_le16(raw_data + 2)); input_report_abs(input, ABS_Y, get_unaligned_le16(raw_data + 4)); input_report_abs(input, ABS_PRESSURE, get_unaligned_le16(raw_data + 6)); /* * There is no out of range event, so use a timer for this * when in range we get an event approx. every 8 ms. */ mod_timer(&data->inrange_timer, jiffies + msecs_to_jiffies(100)); break; case 0xe0: /* Pad data */ input = data->input_tablet_pad; for (i = 0; i < LETSKETCH_PAD_BUTTONS; i++) input_report_key(input, BTN_0 + i, raw_data[4] == (i + 1)); break; default: hid_warn(data->hdev, "Warning unknown data header: 0x%02x\n", raw_data[0]); return 0; } input_sync(input); return 0; } /* * The tablets magic handshake to put it in raw mode relies on getting * string descriptors. But the firmware is buggy and does not like it if * we do this too fast. Even if we go slow sometimes the usb_string() call * fails. Ignore errors and retry it a couple of times if necessary. */ static int letsketch_get_string(struct usb_device *udev, int index, char *buf, int size) { int i, ret; for (i = 0; i < LETSKETCH_GET_STRING_RETRIES; i++) { usleep_range(5000, 7000); ret = usb_string(udev, index, buf, size); if (ret > 0) return 0; } dev_err(&udev->dev, "Max retries (%d) exceeded reading string descriptor %d\n", LETSKETCH_GET_STRING_RETRIES, index); return ret ? ret : -EIO; } static int letsketch_probe(struct hid_device *hdev, const struct hid_device_id *id) { struct device *dev = &hdev->dev; struct letsketch_data *data; struct usb_interface *intf; struct usb_device *udev; char buf[256]; int i, ret; if (!hid_is_using_ll_driver(hdev, &usb_hid_driver)) return -ENODEV; intf = to_usb_interface(hdev->dev.parent); if (intf->altsetting->desc.bInterfaceNumber != LETSKETCH_RAW_IF) return -ENODEV; /* Ignore the other interfaces */ udev = interface_to_usbdev(intf); /* * Instead of using a set-feature request, or even a custom USB ctrl * message the tablet needs this elaborate magic reading of USB * string descriptors to kick it into raw mode. This is what the * Windows drivers are seen doing in an USB trace under Windows. */ for (i = LETSKETCH_INFO_STR_IDX_BEGIN; i <= LETSKETCH_INFO_STR_IDX_END; i++) { ret = letsketch_get_string(udev, i, buf, sizeof(buf)); if (ret) return ret; hid_info(hdev, "Device info: %s\n", buf); } for (i = 1; i <= 250; i++) { ret = letsketch_get_string(udev, i, buf, sizeof(buf)); if (ret) return ret; } ret = letsketch_get_string(udev, 0x64, buf, sizeof(buf)); if (ret) return ret; ret = letsketch_get_string(udev, LETSKETCH_INFO_STR_IDX_BEGIN, buf, sizeof(buf)); if (ret) return ret; /* * The tablet should be in raw mode now, end with a final delay before * doing further IO to the device. */ usleep_range(5000, 7000); ret = hid_parse(hdev); if (ret) return ret; data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); if (!data) return -ENOMEM; data->hdev = hdev; timer_setup(&data->inrange_timer, letsketch_inrange_timeout, 0); hid_set_drvdata(hdev, data); ret = letsketch_setup_input_tablet(data); if (ret) return ret; ret = letsketch_setup_input_tablet_pad(data); if (ret) return ret; return hid_hw_start(hdev, HID_CONNECT_HIDRAW); } static const struct hid_device_id letsketch_devices[] = { { HID_USB_DEVICE(USB_VENDOR_ID_LETSKETCH, USB_DEVICE_ID_WP9620N) }, { } }; MODULE_DEVICE_TABLE(hid, letsketch_devices); static struct hid_driver letsketch_driver = { .name = "letsketch", .id_table = letsketch_devices, .probe = letsketch_probe, .raw_event = letsketch_raw_event, }; module_hid_driver(letsketch_driver); MODULE_AUTHOR("Hans de Goede "); MODULE_LICENSE("GPL");