samples/hid/hid_surface_dial.bpf.c

   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;