// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (c) 2021 Hans de Goede <[email protected]>
*
* 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 <linux/device.h>
#include <linux/input.h>
#include <linux/hid.h>
#include <linux/module.h>
#include <linux/timer.h>
#include <linux/usb.h>
#include <linux/unaligned.h>
#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_usb(hdev))
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 <[email protected]>");
MODULE_DESCRIPTION("Driver for the LetSketch / VSON WP9620N drawing tablet");
MODULE_LICENSE("GPL");
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