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USB : Standard five keys mouse in qemu
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‎debug/usb/README.md‎

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@@ -8,7 +8,7 @@ hid report descriptors在usb描述符中的关系
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![report descriptors](./reportid.png)
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下面是一个三个按键的标准鼠标
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## 标准三键的鼠标
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![3 buttons mouse](./mouse.png)
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@@ -301,6 +301,195 @@ qemu代码里描述上述鼠标按键的结构时HIDPointerEvent
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0xc0, /* End Collection */
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};
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## 标准五键(两个侧键)鼠标
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鼠标按键用button1, button2, button3...来命名
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qemu代码中用结构体HIDPointerEvent来描述鼠标的数据
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typedef struct HIDPointerEvent {
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int32_t xdx, ydy; /* relative iff it's a mouse, otherwise absolute */
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int32_t dz, buttons_state;
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} HIDPointerEvent;
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其中buttons_state每一位表示按键,这里用int32_t说明可以支持32个按键(一般支持8个按键即可uint8_t)
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bit1对应button1, bit2对应button2,以此类推
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一般操作系统中将对应按键映射成不同功能
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button1:left(鼠标左键)
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button2:right(鼠标右键)
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button3:middle(滚轮按键)
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button4:side(侧边按键1)
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button5:extra(侧边按键2)
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鼠标设备上报buttonN经过系统映射后变为对应的功能按键(left,right,middle...)
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大部分标准5键鼠标都是按照上面的进行映射(button4,button5的映射非强制)
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所以在qemu模拟的鼠标中可以将button4和button5和side和extra对应以达到同大部分物理鼠标效果
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### 下面以spice-input和USB HID鼠标为例说明
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spice捕获坐标后传递给qemu的input子系统来作为鼠标数据提供给虚拟鼠标设备
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SpiceInput(spice-input.c)->InputCore(input.c)->USB HID Device(hid.c)
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SpiceInput中通过button_mask来传入鼠标按键掩码值
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下面代将button4配置为side, button5配置为extra
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```c
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static void spice_update_buttons(QemuSpicePointer *pointer,
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int wheel, uint32_t button_mask)
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{
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static uint32_t bmap[INPUT_BUTTON__MAX] = {
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[INPUT_BUTTON_LEFT] = 0x01, /* button 1 */
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[INPUT_BUTTON_MIDDLE] = 0x04, /* button 3 */
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[INPUT_BUTTON_RIGHT] = 0x02, /* button 2 */
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[INPUT_BUTTON_WHEEL_UP] = 0x40, /* button 7 */
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[INPUT_BUTTON_WHEEL_DOWN] = 0x80, /* button 8 */
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[INPUT_BUTTON_SIDE] = 0x08, /* button 4 */
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[INPUT_BUTTON_EXTRA] = 0x10, /* button 5 */
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};
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if (wheel < 0) {
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button_mask |= 0x40;
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}
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if (wheel > 0) {
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button_mask |= 0x80;
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}
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```
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qemu中通过文件qapi/ui.json来生成头文件中对应的按键枚举
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```c
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{ 'enum' : 'InputButton',
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'data' : [ 'left', 'middle', 'right', 'wheel-up', 'wheel-down', 'side',
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'extra' ] }
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下面是生成的对应的枚举值
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typedef enum InputButton {
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INPUT_BUTTON_LEFT = 0,
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INPUT_BUTTON_MIDDLE = 1,
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INPUT_BUTTON_RIGHT = 2,
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INPUT_BUTTON_WHEEL_UP = 3,
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INPUT_BUTTON_WHEEL_DOWN = 4,
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INPUT_BUTTON_SIDE = 5,
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INPUT_BUTTON_EXTRA = 6,
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INPUT_BUTTON__MAX = 7,
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} InputButton;
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```
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SpiceInput调用InputCore的接口最终调入对应的设备模拟设备处理函数,这里假设是HID设备(hid_pointer_event)
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```c
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static void hid_pointer_event(DeviceState *dev, QemuConsole *src,
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InputEvent *evt)
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{
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static const int bmap[INPUT_BUTTON__MAX] = {
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[INPUT_BUTTON_LEFT] = 0x01,
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[INPUT_BUTTON_RIGHT] = 0x02,
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[INPUT_BUTTON_MIDDLE] = 0x04,
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[INPUT_BUTTON_SIDE] = 0x08,
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[INPUT_BUTTON_EXTRA] = 0x10,
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};
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```
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还有一个需要注意的是hid report descriptor
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其中下面的配置是同时上报8个按键
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```c
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static const uint8_t qemu_tablet_hid_report_descriptor[] = {
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0x05, 0x01, /* Usage Page (Generic Desktop) */
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0x09, 0x02, /* Usage (Mouse) */
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0xa1, 0x01, /* Collection (Application) */
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0x09, 0x01, /* Usage (Pointer) */
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0xa1, 0x00, /* Collection (Physical) */
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0x05, 0x09, /* Usage Page (Button) */
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0x19, 0x01, /* Usage Minimum (1) */
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0x29, 0x08, /* Usage Maximum (8) */
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0x15, 0x00, /* Logical Minimum (0) */
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0x25, 0x01, /* Logical Maximum (1) */
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0x95, 0x08, /* Report Count (8) */
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0x75, 0x01, /* Report Size (1) */
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0x81, 0x02, /* Input (Data, Variable, Absolute) */
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0x05, 0x01, /* Usage Page (Generic Desktop) */
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0x09, 0x30, /* Usage (X) */
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0x09, 0x31, /* Usage (Y) */
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0x15, 0x00, /* Logical Minimum (0) */
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0x26, 0xff, 0x7f, /* Logical Maximum (0x7fff) */
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0x35, 0x00, /* Physical Minimum (0) */
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0x46, 0xff, 0x7f, /* Physical Maximum (0x7fff) */
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0x75, 0x10, /* Report Size (16) */
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0x95, 0x02, /* Report Count (2) */
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0x81, 0x02, /* Input (Data, Variable, Absolute) */
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0x05, 0x01, /* Usage Page (Generic Desktop) */
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0x09, 0x38, /* Usage (Wheel) */
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0x15, 0x81, /* Logical Minimum (-0x7f) */
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0x25, 0x7f, /* Logical Maximum (0x7f) */
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0x35, 0x00, /* Physical Minimum (same as logical) */
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0x45, 0x00, /* Physical Maximum (same as logical) */
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0x75, 0x08, /* Report Size (8) */
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0x95, 0x01, /* Report Count (1) */
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0x81, 0x06, /* Input (Data, Variable, Relative) */
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0xc0, /* End Collection */
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0xc0, /* End Collection */
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};
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/* HID描述符长度需要对应修改 */
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static const USBDescIface desc_iface_tablet = {
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...
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/* HID descriptor */
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.data = (uint8_t[]) {
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0x09, /* u8 bLength */
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USB_DT_HID, /* u8 bDescriptorType */
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0x01, 0x00, /* u16 HID_class */
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0x00, /* u8 country_code */
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0x01, /* u8 num_descriptors */
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USB_DT_REPORT, /* u8 type: Report */
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sizeof(qemu_tablet_hid_report_descriptor) / sizeof(uint8_t), 0, /* u16 len */
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},
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...
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```
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### 调试输入数据
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确认SpiceInput输出的数据可以在InputCore中打开调试
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(qemu) trace-event input_event_btn on
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or
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virsh qemu-monitor-command <domain> --hmp trace-event input_event_btn on
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确认模拟HID鼠标上报的数据,在下面函数中用gdb打印对应数据
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USB数据包的处理函数usb_handle_packet调用流程如下
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```c
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usb_handle_packet
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usb_hid_handle_data
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hid_pointer_poll
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int hid_pointer_poll(HIDState *hs, uint8_t *buf, int len)
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case HID_TABLET:
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if (len > l) {
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buf[l++] = e->buttons_state;
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}
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if (len > l) {
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buf[l++] = dx & 0xff;
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}
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if (len > l) {
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buf[l++] = dx >> 8;
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}
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if (len > l) {
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buf[l++] = dy & 0xff;
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}
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if (len > l) {
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buf[l++] = dy >> 8;
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}
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if (len > l) {
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buf[l++] = dz;
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}
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break;
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(gdb) printf "0x%02x, 0x%02x, 0x%02x, 0x%02x, 0x%02x 0x%02x\n", buf[0], buf[1], buf[2], buf[3], buf[4], buf[5]
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```
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其中使用USBlyzer抓到的raw data区域对应的数据为上面的buf
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## How to retrieve the report descriptors in linux
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[Ref: get usb report descriptor](https://www.slashdev.ca/2010/05/08/get-usb-report-descriptor-with-linux/)

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