1 // SPDX-License-Identifier: GPL-2.0-only
18 /* Filled in by udev-hid-bpf */
27  * tablet mode. In firmware mode (out of the box) the tablet sends button events
33  * To switch the tablet use e.g.  https://github.com/whot/huion-switcher
36  * This BPF works for both modes. The huion-switcher tool sets the
37  * HUION_FIRMWARE_ID udev property - if that is set then we disable the firmware
49  * # 0xa1, 0x01,                    // Collection (Application)                  5
59  * https://github.com/whot/huion-switcher
75  * # 0x09, 0x3c,          //     Usage (Invert)                        18 <-- has no Invert eraser
89  * # 0x55, 0x0d,          //     Unit Exponent (-3)                    46 <-- change to -2
90  * # 0x65, 0x33,          //     Unit (EnglishLinear: in³)             48 <-- change in³ to in
93  * # 0x46, 0x00, 0x08,    //     Physical Maximum (2048)               55 <-- invalid size
103  * # 0x09, 0x3d,          //     Usage (X Tilt)                        77 <-- No tilt reported
105  * # 0x15, 0x81,          //     Logical Minimum (-127)                81
171 		// -- Byte 0 in report
178 			// Byte 1 in report - just exists so we get to be a tablet pad
185 			// Bytes 2/3 in report - just exists so we get to be a tablet pad
194 			LogicalMinimum_i8(-1)
199 			// Byte 5 is the button state
218 		// -- Byte 0 in report
222 			// -- Byte 1 in report
241 				UnitExponent(-1)
253 				Input(Var|Abs) // Bytes 4+5
296 				UnitExponent(-1)
310 				// Bytes 4/5 in report
338 			// Bytes 2/3 - x/y just exist so we get to be a tablet pad
345 			// Byte 4 is the button state
356 			// Byte 5 is the wheel
359 			LogicalMinimum_i8(-1)
382 	__s32 rdesc_size = hctx->size;  in SEC()
394 				      sizeof(EXPECTED_FIRMWARE_ID) - 1) == 0;  in SEC()
414 	 * the udev property (e.g. huion-switcher run manually)  in SEC()
434 		/* Nicely enough, this device only supports one button down at a time so  in SEC()
436 		 *   Button released: 03 00 00 00 00 00 00 00  in SEC()
437 		 *   Button 1: 03 00 05 00 00 00 00 00 -> b  in SEC()
438 		 *   Button 2: 03 00 0c 00 00 00 00 00 -> i  in SEC()
439 		 *   Button 3: 03 00 08 00 00 00 00 00 -> e  in SEC()
440 		 *   Button 4: 03 01 16 00 00 00 00 00 -> Ctrl S  in SEC()
441 		 *   Button 5: 03 00 2c 00 00 00 00 00 -> space  in SEC()
442 		 *   Button 6: 03 05 1d 00 00 00 00 00 -> Ctrl Alt Z  in SEC()
444 		 *   Wheel down: 03 01 2d 00 00 00 00 00 -> Ctrl -  in SEC()
445 		 *   Wheel up:   03 01 2e 00 00 00 00 00 -> Ctrl =  in SEC()
447 		__u8 button = 0;  in SEC()  local
454 			button = 1;  in SEC()
457 			button = 2;  in SEC()
460 			button = 3;  in SEC()
463 			button = 4;  in SEC()
466 			button = 5;  in SEC()
469 			button = 6;  in SEC()
472 			wheel = -1;  in SEC()
480 		__u8 report[6] = {PAD_REPORT_ID, 0x0, 0x0, 0x0, wheel, button};  in SEC()
505 				if (data[5] == 2)  in SEC()
508 					wheel = data[5];  in SEC()
517 			pad_report->report_id = PAD_REPORT_ID;  in SEC()
518 			pad_report->btn_stylus = 0;  in SEC()
519 			pad_report->x = 0;  in SEC()
520 			pad_report->y = 0;  in SEC()
521 			pad_report->buttons = last_button_state;  in SEC()
522 			pad_report->wheel = wheel;  in SEC()
541 	switch (ctx->rdesc_size) {  in probe()
545 		ctx->retval = 0;  in probe()
548 		ctx->retval = -EINVAL;  in probe()