The XP-PEN Deco Mini 4 is a UGEE device with a frame with 6 buttons. Its pen has 2 buttons and supports pressure reporting. Fix their report descriptors and transform the frame button events to support it. Link: https://gitlab.freedesktop.org/libevdev/udev-hid-bpf/-/merge_requests/88 Signed-off-by: José Expósito <jose.exposito89@xxxxxxxxx> Signed-off-by: Benjamin Tissoires <bentiss@xxxxxxxxxx> --- drivers/hid/bpf/progs/XPPen__DecoMini4.bpf.c | 231 +++++++++++++++++++++++++++ 1 file changed, 231 insertions(+) diff --git a/drivers/hid/bpf/progs/XPPen__DecoMini4.bpf.c b/drivers/hid/bpf/progs/XPPen__DecoMini4.bpf.c new file mode 100644 index 000000000000..46d5c459d0c9 --- /dev/null +++ b/drivers/hid/bpf/progs/XPPen__DecoMini4.bpf.c @@ -0,0 +1,231 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Copyright (c) 2024 José Expósito + */ + +#include "vmlinux.h" +#include "hid_bpf.h" +#include "hid_bpf_helpers.h" +#include <bpf/bpf_tracing.h> + +#define VID_UGEE 0x28BD +#define PID_DECO_MINI_4 0x0929 +#define RDESC_SIZE_PAD 177 +#define RDESC_SIZE_PEN 109 +#define PAD_REPORT_ID 0x06 + +/* + * XP-Pen devices return a descriptor with the values the driver should use when + * one of its interfaces is queried. For this device the descriptor is: + * + * 0E 03 60 4F 88 3B 06 00 FF 1F D8 13 + * ----- ----- ----- ----- + * | | | | + * | | | `- Resolution: 5080 (13d8) + * | | `- Maximum pressure: 8191 (1FFF) + * | `- Logical maximum Y: 15240 (3B88) + * `- Logical maximum X: 20320 (4F60) + * + * The physical maximum is calculated as (logical_max * 1000) / resolution. + */ +#define LOGICAL_MAX_X 0x60, 0x4F +#define LOGICAL_MAX_Y 0x88, 0x3B +#define PHYSICAL_MAX_X 0xA0, 0x0F +#define PHYSICAL_MAX_Y 0xB8, 0x0B +#define PRESSURE_MAX 0xFF, 0x1F + +HID_BPF_CONFIG( + HID_DEVICE(BUS_USB, HID_GROUP_GENERIC, VID_UGEE, PID_DECO_MINI_4) +); + +/* + * The tablet send these values when the pad buttons are pressed individually: + * + * Buttons released: 06 00 00 00 00 00 00 00 + * Button 1: 06 00 05 00 00 00 00 00 -> b + * Button 2: 06 00 08 00 00 00 00 00 -> e + * Button 3: 06 04 00 00 00 00 00 00 -> LAlt + * Button 4: 06 00 2c 00 00 00 00 00 -> Space + * Button 5: 06 01 16 00 00 00 00 00 -> LControl + s + * Button 6: 06 01 1d 00 00 00 00 00 -> LControl + z + * + * When multiple buttons are pressed at the same time, the values used to + * identify the buttons are identical, but they appear in different bytes of the + * record. For example, when button 2 (0x08) and button 1 (0x05) are pressed, + * this is the report: + * + * Buttons 2 and 1: 06 00 08 05 00 00 00 00 -> e + b + * + * Buttons 1, 2, 4, 5 and 6 can be matched by finding their values in the + * report. + * + * Button 3 is pressed when the 3rd bit is 1. For example, pressing buttons 3 + * and 5 generates this report: + * + * Buttons 3 and 5: 06 05 16 00 00 00 00 00 -> LControl + LAlt + s + * -- -- + * | | + * | `- Button 5 (0x16) + * `- 0x05 = 0101. Button 3 is pressed + * ^ + * + * pad_buttons contains a list of buttons that can be matched in + * HID_BPF_DEVICE_EVENT. Button 3 as it has a dedicated bit. + */ +static const __u8 pad_buttons[] = { 0x05, 0x08, 0x00, 0x2C, 0x16, 0x1D }; + +static const __u8 fixed_pad_rdesc[] = { + 0x05, 0x01, /* Usage Page (Desktop), */ + 0x09, 0x07, /* Usage (Keypad), */ + 0xA1, 0x01, /* Collection (Application), */ + 0x85, 0x06, /* Report ID (6), */ + 0x05, 0x0D, /* Usage Page (Digitizer), */ + 0x09, 0x39, /* Usage (Tablet Function Keys), */ + 0xA0, /* Collection (Physical), */ + 0x05, 0x09, /* Usage Page (Button), */ + 0x75, 0x01, /* Report Size (1), */ + 0x95, 0x06, /* Report Count (6), */ + 0x19, 0x01, /* Usage Minimum (01h), */ + 0x29, 0x06, /* Usage Maximum (06h), */ + 0x14, /* Logical Minimum (0), */ + 0x25, 0x01, /* Logical Maximum (1), */ + 0x81, 0x02, /* Input (Variable), */ + 0x95, 0x32, /* Report Count (50), */ + 0x81, 0x01, /* Input (Constant), */ + 0xC0, /* End Collection, */ + 0xC0 /* End Collection */ +}; + +static const __u8 fixed_pen_rdesc[] = { + 0x05, 0x0d, /* Usage Page (Digitizers), */ + 0x09, 0x01, /* Usage (Digitizer), */ + 0xa1, 0x01, /* Collection (Application), */ + 0x85, 0x07, /* Report ID (7), */ + 0x09, 0x20, /* Usage (Stylus), */ + 0xa1, 0x00, /* Collection (Physical), */ + 0x09, 0x42, /* Usage (Tip Switch), */ + 0x09, 0x44, /* Usage (Barrel Switch), */ + 0x09, 0x46, /* Usage (Tablet Pick), */ + 0x75, 0x01, /* Report Size (1), */ + 0x95, 0x03, /* Report Count (3), */ + 0x14, /* Logical Minimum (0), */ + 0x25, 0x01, /* Logical Maximum (1), */ + 0x81, 0x02, /* Input (Variable), */ + 0x95, 0x02, /* Report Count (2), */ + 0x81, 0x03, /* Input (Constant, Variable), */ + 0x09, 0x32, /* Usage (In Range), */ + 0x95, 0x01, /* Report Count (1), */ + 0x81, 0x02, /* Input (Variable), */ + 0x95, 0x02, /* Report Count (2), */ + 0x81, 0x03, /* Input (Constant, Variable), */ + 0x75, 0x10, /* Report Size (16), */ + 0x95, 0x01, /* Report Count (1), */ + 0x35, 0x00, /* Physical Minimum (0), */ + 0xa4, /* Push, */ + 0x05, 0x01, /* Usage Page (Desktop), */ + 0x09, 0x30, /* Usage (X), */ + 0x65, 0x13, /* Unit (Inch), */ + 0x55, 0x0d, /* Unit Exponent (-3), */ + 0x26, LOGICAL_MAX_X, /* Logical Maximum, */ + 0x46, PHYSICAL_MAX_X, /* Physical Maximum, */ + 0x81, 0x02, /* Input (Variable), */ + 0x09, 0x31, /* Usage (Y), */ + 0x26, LOGICAL_MAX_Y, /* Logical Maximum, */ + 0x46, PHYSICAL_MAX_Y, /* Physical Maximum, */ + 0x81, 0x02, /* Input (Variable), */ + 0xb4, /* Pop, */ + 0x09, 0x30, /* Usage (Tip Pressure), */ + 0x45, 0x00, /* Physical Maximum (0), */ + 0x26, PRESSURE_MAX, /* Logical Maximum, */ + 0x75, 0x0D, /* Report Size (13), */ + 0x95, 0x01, /* Report Count (1), */ + 0x81, 0x02, /* Input (Variable), */ + 0x75, 0x01, /* Report Size (1), */ + 0x95, 0x13, /* Report Count (19), */ + 0x81, 0x01, /* Input (Constant), */ + 0xc0, /* End Collection, */ + 0xc0, /* End Collection */ +}; + +static const size_t fixed_pad_rdesc_size = sizeof(fixed_pad_rdesc); +static const size_t fixed_pen_rdesc_size = sizeof(fixed_pen_rdesc); + +SEC(HID_BPF_RDESC_FIXUP) +int BPF_PROG(hid_rdesc_fixup_xppen_deco_mini_4, struct hid_bpf_ctx *hctx) +{ + __u8 *data = hid_bpf_get_data(hctx, 0, HID_MAX_DESCRIPTOR_SIZE); + + if (!data) + return 0; /* EPERM check */ + + if (hctx->size == RDESC_SIZE_PAD) { + __builtin_memcpy(data, fixed_pad_rdesc, fixed_pad_rdesc_size); + return fixed_pad_rdesc_size; + } else if (hctx->size == RDESC_SIZE_PEN) { + __builtin_memcpy(data, fixed_pen_rdesc, fixed_pen_rdesc_size); + return fixed_pen_rdesc_size; + } + + return 0; +} + +SEC(HID_BPF_DEVICE_EVENT) +int BPF_PROG(hid_device_event_xppen_deco_mini_4, struct hid_bpf_ctx *hctx) +{ + __u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 8 /* size */); + __u8 button_mask = 0; + int d, b; + + if (!data) + return 0; /* EPERM check */ + + if (data[0] != PAD_REPORT_ID) + return 0; + + /* data[1] stores the status of BTN_2 in the 3rd bit*/ + if (data[1] & BIT(2)) + button_mask |= BIT(2); + + /* The rest of the descriptor stores the buttons as in pad_buttons */ + for (d = 2; d < 8; d++) { + for (b = 0; b < sizeof(pad_buttons); b++) { + if (data[d] != 0 && data[d] == pad_buttons[b]) + button_mask |= BIT(b); + } + } + + __u8 report[8] = {PAD_REPORT_ID, button_mask, 0x00}; + + __builtin_memcpy(data, report, sizeof(report)); + + return 0; +} + +HID_BPF_OPS(deco_mini_4) = { + .hid_device_event = (void *)hid_device_event_xppen_deco_mini_4, + .hid_rdesc_fixup = (void *)hid_rdesc_fixup_xppen_deco_mini_4, +}; + +SEC("syscall") +int probe(struct hid_bpf_probe_args *ctx) +{ + /* + * The device has 2 modes: The compatibility mode, enabled by default, + * and the raw mode, that can be activated by sending a buffer of magic + * data to a certain USB endpoint. + * + * Depending on the mode, different interfaces of the device are used: + * - First interface: Pad in compatibility mode + * - Second interface: Pen in compatibility mode + * - Third interface: Only used in raw mode + * + * We'll use the device in compatibility mode. + */ + ctx->retval = ctx->rdesc_size != RDESC_SIZE_PAD && + ctx->rdesc_size != RDESC_SIZE_PEN; + if (ctx->retval) + ctx->retval = -EINVAL; + + return 0; +} + +char _license[] SEC("license") = "GPL"; -- 2.44.0
