// SPDX-License-Identifier: GPL-2.0-or-later
//
// The devices the kernel implements itself, as /sys and udev see them.
//
// /dev holds them already (kernel/fs/devfs.c). This is the other half of what
// udev needs: for each node a place in /sys/devices, the class and dev/ links
// that lead back to it, the facts udev's rules read (MAJOR, MINOR, DEVNAME,
// input capabilities), and a way to announce it on the uevent netlink socket.
#pragma once

#include "core/types.h"

#define KDEV_NAME     24
#define KDEV_DEVNAME  32
#define KDEV_BLK0     256       // kdev indexes from here are block devices

enum { KD_NONE, KD_KEYBOARD, KD_MOUSE };

struct kdev {
  char  subsys[16];             // class: input, mem, tty, graphics, block
  char  name[KDEV_NAME];        // directory name under the parent
  char  devname[KDEV_DEVNAME];  // path below /dev, "" for a device with no node
  short major, minor;
  int   block;
  int   parent;                 // kdev index of the device it hangs off, or -1
  int   cap;                    // KD_*: what an input device can do
};

int  kdev_nsubsys(void);
const char *kdev_subsys(int s);

// Index of the Nth device that exists, 0.. until -1.
int  kdev_nth(int n);
int  kdev_get(int i, struct kdev *k);
// The numbers stat() shows for its node, which are what /sys must show too.
void kdev_numbers(const struct kdev *k, int *maj, int *min);

// "devices/virtual/input/input0/event0": where it lives below /sys.
int  kdev_path(int i, char *buf, int cap);

// Announce a device on the uevent socket: action is "add", "remove", "change".
void kdev_uevent(int i, const char *action);
// What reading a device's `uevent` file says.
int  kdev_uevent_text(int i, char *buf, int cap);