// SPDX-License-Identifier: GPL-2.0-or-later
#pragma once

// /dev/ldls -- Linux drivers, in the kernel. docs/architecture/ldls.md.
//
// The device is a control channel and nothing else: a module is handed over
// whole, as bytes, together with the BTF of the kernel it was built for, and
// the kernel does the rest -- loading, linking, init_module, probe, and
// bringing the interface up -- on a thread of its own. What happened comes
// back as text, because the useful answer to "did it work" is the driver's
// own account of what it found.
//
//     ldls load /lib/modules/e1000.ko
//     ldls list
//     ldls unload e1000
//
// Shared with userland (cmd/ldls), so it is spelled in plain C types.

#define LDLS_MAJOR 13

// Take the device even if a kernel driver holds it, provided that driver can
// be asked to let go. Without this LDLS only takes devices nothing else
// drives, which is the right default at boot: the kernel's own driver is on
// the path to a shell, and the hosted one is the better one only when someone
// says so.
#define LDLS_TAKE     0x1
// Load and link, run init_module, and stop: no device is probed. For a
// library module (mii, libphy) whose job is to export symbols to the next.
#define LDLS_NOPROBE  0x2

struct ldls_load {
  unsigned long long ko;        // in: the module image
  unsigned long long kolen;
  unsigned long long btf;       // in: the kernel's BTF, /sys/kernel/btf/vmlinux
  unsigned long long btflen;
  unsigned long long msg;       // out: what happened, NUL-terminated
  unsigned int       msgcap;
  unsigned int       flags;     // LDLS_*
  int                bus, slot, func;   // -1 for "whichever matches"
  unsigned int       hz;        // CONFIG_HZ of that kernel; 0 means 1000
  int                id;        // out: the module's id, for unload
};

struct ldls_text {
  unsigned long long buf;       // out
  unsigned int       cap;
  unsigned int       pad;
};

#define LDLSIOC_LOAD    0xD000  // struct ldls_load
#define LDLSIOC_UNLOAD  0xD001  // in: int id
#define LDLSIOC_LIST    0xD002  // struct ldls_text
#define LDLSIOC_LOG     0xD003  // struct ldls_text, in: pad = id