/* SPDX-License-Identifier: GPL-2.0-only */
/* Copyright (c) 2022 Benjamin Tissoires
 */

#ifndef __HID_BPF_HELPERS_H
#define __HID_BPF_HELPERS_H

/* "undefine" structs and enums in vmlinux.h, because we "override" them below */
#define bpf_wq bpf_wq___not_used
#define hid_bpf_ctx hid_bpf_ctx___not_used
#define hid_bpf_ops hid_bpf_ops___not_used
#define hid_device hid_device___not_used
#define hid_report_type hid_report_type___not_used
#define hid_class_request hid_class_request___not_used
#define hid_bpf_attach_flags hid_bpf_attach_flags___not_used
#define HID_INPUT_REPORT         HID_INPUT_REPORT___not_used
#define HID_OUTPUT_REPORT        HID_OUTPUT_REPORT___not_used
#define HID_FEATURE_REPORT       HID_FEATURE_REPORT___not_used
#define HID_REPORT_TYPES         HID_REPORT_TYPES___not_used
#define HID_REQ_GET_REPORT       HID_REQ_GET_REPORT___not_used
#define HID_REQ_GET_IDLE         HID_REQ_GET_IDLE___not_used
#define HID_REQ_GET_PROTOCOL     HID_REQ_GET_PROTOCOL___not_used
#define HID_REQ_SET_REPORT       HID_REQ_SET_REPORT___not_used
#define HID_REQ_SET_IDLE         HID_REQ_SET_IDLE___not_used
#define HID_REQ_SET_PROTOCOL     HID_REQ_SET_PROTOCOL___not_used

/* do not define kfunc through vmlinux.h as this messes up our custom hack */
#define BPF_NO_KFUNC_PROTOTYPES

#include "vmlinux.h"

#undef bpf_wq
#undef hid_bpf_ctx
#undef hid_bpf_ops
#undef hid_device
#undef hid_report_type
#undef hid_class_request
#undef hid_bpf_attach_flags
#undef HID_INPUT_REPORT
#undef HID_OUTPUT_REPORT
#undef HID_FEATURE_REPORT
#undef HID_REPORT_TYPES
#undef HID_REQ_GET_REPORT
#undef HID_REQ_GET_IDLE
#undef HID_REQ_GET_PROTOCOL
#undef HID_REQ_SET_REPORT
#undef HID_REQ_SET_IDLE
#undef HID_REQ_SET_PROTOCOL

#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
#include <linux/const.h>

enum hid_report_type {
        HID_INPUT_REPORT                = 0,
        HID_OUTPUT_REPORT               = 1,
        HID_FEATURE_REPORT              = 2,

        HID_REPORT_TYPES,
};

struct hid_device {
        unsigned int id;
} __attribute__((preserve_access_index));

struct bpf_wq {
        __u64 __opaque[2];
};

struct hid_bpf_ctx {
        struct hid_device *hid;
        __u32 allocated_size;
        union {
                __s32 retval;
                __s32 size;
        };
} __attribute__((preserve_access_index));

enum hid_class_request {
        HID_REQ_GET_REPORT              = 0x01,
        HID_REQ_GET_IDLE                = 0x02,
        HID_REQ_GET_PROTOCOL            = 0x03,
        HID_REQ_SET_REPORT              = 0x09,
        HID_REQ_SET_IDLE                = 0x0A,
        HID_REQ_SET_PROTOCOL            = 0x0B,
};

struct hid_bpf_ops {
        int                     hid_id;
        u32                     flags;
        struct list_head        list;
        int (*hid_device_event)(struct hid_bpf_ctx *ctx, enum hid_report_type report_type,
                                u64 source);
        int (*hid_rdesc_fixup)(struct hid_bpf_ctx *ctx);
        int (*hid_hw_request)(struct hid_bpf_ctx *ctx, unsigned char reportnum,
                               enum hid_report_type rtype, enum hid_class_request reqtype,
                               u64 source);
        int (*hid_hw_output_report)(struct hid_bpf_ctx *ctx, u64 source);
        struct hid_device *hdev;
};

#ifndef BPF_F_BEFORE
#define BPF_F_BEFORE (1U << 3)
#endif

/* following are kfuncs exported by HID for HID-BPF */
extern __u8 *hid_bpf_get_data(struct hid_bpf_ctx *ctx,
                              unsigned int offset,
                              const size_t __sz) __weak __ksym;
extern struct hid_bpf_ctx *hid_bpf_allocate_context(unsigned int hid_id) __weak __ksym;
extern void hid_bpf_release_context(struct hid_bpf_ctx *ctx) __weak __ksym;
extern int hid_bpf_hw_request(struct hid_bpf_ctx *ctx,
                              __u8 *data,
                              size_t buf__sz,
                              enum hid_report_type type,
                              enum hid_class_request reqtype) __weak __ksym;
extern int hid_bpf_hw_output_report(struct hid_bpf_ctx *ctx,
                                    __u8 *buf, size_t buf__sz) __weak __ksym;
extern int hid_bpf_input_report(struct hid_bpf_ctx *ctx,
                                enum hid_report_type type,
                                __u8 *data,
                                size_t buf__sz) __weak __ksym;
extern int hid_bpf_try_input_report(struct hid_bpf_ctx *ctx,
                                    enum hid_report_type type,
                                    __u8 *data,
                                    size_t buf__sz) __weak __ksym;

/* bpf_wq implementation */
extern int bpf_wq_init(struct bpf_wq *wq, void *p__map, unsigned int flags) __weak __ksym;
extern int bpf_wq_start(struct bpf_wq *wq, unsigned int flags) __weak __ksym;
extern int bpf_wq_set_callback(struct bpf_wq *wq,
                int (*callback_fn)(void *, int *, void *),
                unsigned int flags) __weak __ksym;

#endif /* __HID_BPF_HELPERS_H */