1 // SPDX-License-Identifier: GPL-2.0-only 2 /* Copyright (c) 2022 Benjamin Tissoires 3 */ 4 5 #include "vmlinux.h" 6 #include <bpf/bpf_helpers.h> 7 #include <bpf/bpf_tracing.h> 8 #include "hid_bpf_helpers.h" 9 10 #define HID_UP_BUTTON 0x0009 11 #define HID_GD_WHEEL 0x0038 12 13 SEC("fmod_ret/hid_bpf_device_event") 14 int BPF_PROG(hid_event, struct hid_bpf_ctx *hctx) 15 { 16 __u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 9 /* size */); 17 18 if (!data) 19 return 0; /* EPERM check */ 20 21 /* Touch */ 22 data[1] &= 0xfd; 23 24 /* X */ 25 data[4] = 0; 26 data[5] = 0; 27 28 /* Y */ 29 data[6] = 0; 30 data[7] = 0; 31 32 return 0; 33 } 34 35 /* 72 == 360 / 5 -> 1 report every 5 degrees */ 36 int resolution = 72; 37 int physical = 5; 38 39 struct haptic_syscall_args { 40 unsigned int hid; 41 int retval; 42 }; 43 44 static __u8 haptic_data[8]; 45 46 SEC("syscall") 47 int set_haptic(struct haptic_syscall_args *args) 48 { 49 struct hid_bpf_ctx *ctx; 50 const size_t size = sizeof(haptic_data); 51 u16 *res; 52 int ret; 53 54 if (size > sizeof(haptic_data)) 55 return -7; /* -E2BIG */ 56 57 ctx = hid_bpf_allocate_context(args->hid); 58 if (!ctx) 59 return -1; /* EPERM check */ 60 61 haptic_data[0] = 1; /* report ID */ 62 63 ret = hid_bpf_hw_request(ctx, haptic_data, size, HID_FEATURE_REPORT, HID_REQ_GET_REPORT); 64 65 bpf_printk("probed/remove event ret value: %d", ret); 66 bpf_printk("buf: %02x %02x %02x", 67 haptic_data[0], 68 haptic_data[1], 69 haptic_data[2]); 70 bpf_printk(" %02x %02x %02x", 71 haptic_data[3], 72 haptic_data[4], 73 haptic_data[5]); 74 bpf_printk(" %02x %02x", 75 haptic_data[6], 76 haptic_data[7]); 77 78 /* whenever resolution multiplier is not 3600, we have the fixed report descriptor */ 79 res = (u16 *)&haptic_data[1]; 80 if (*res != 3600) { 81 // haptic_data[1] = 72; /* resolution multiplier */ 82 // haptic_data[2] = 0; /* resolution multiplier */ 83 // haptic_data[3] = 0; /* Repeat Count */ 84 haptic_data[4] = 3; /* haptic Auto Trigger */ 85 // haptic_data[5] = 5; /* Waveform Cutoff Time */ 86 // haptic_data[6] = 80; /* Retrigger Period */ 87 // haptic_data[7] = 0; /* Retrigger Period */ 88 } else { 89 haptic_data[4] = 0; 90 } 91 92 ret = hid_bpf_hw_request(ctx, haptic_data, size, HID_FEATURE_REPORT, HID_REQ_SET_REPORT); 93 94 bpf_printk("set haptic ret value: %d -> %d", ret, haptic_data[4]); 95 96 args->retval = ret; 97 98 hid_bpf_release_context(ctx); 99 100 return 0; 101 } 102 103 /* Convert REL_DIAL into REL_WHEEL */ 104 SEC("fmod_ret/hid_bpf_rdesc_fixup") 105 int BPF_PROG(hid_rdesc_fixup, struct hid_bpf_ctx *hctx) 106 { 107 __u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 4096 /* size */); 108 __u16 *res, *phys; 109 110 if (!data) 111 return 0; /* EPERM check */ 112 113 /* Convert TOUCH into a button */ 114 data[31] = HID_UP_BUTTON; 115 data[33] = 2; 116 117 /* Convert REL_DIAL into REL_WHEEL */ 118 data[45] = HID_GD_WHEEL; 119 120 /* Change Resolution Multiplier */ 121 phys = (__u16 *)&data[61]; 122 *phys = physical; 123 res = (__u16 *)&data[66]; 124 *res = resolution; 125 126 /* Convert X,Y from Abs to Rel */ 127 data[88] = 0x06; 128 data[98] = 0x06; 129 130 return 0; 131 } 132 133 char _license[] SEC("license") = "GPL"; 134 u32 _version SEC("version") = 1; 135