Luna/kernel/src/fs/devices/DeviceRegistry.cpp

#include "fs/devices/DeviceRegistry.h"
#include "Log.h"
#include "fs/VFS.h"
#include "fs/devices/ConsoleDevice.h"
#include "fs/devices/FramebufferDevice.h"
#include "fs/devices/FullDevice.h"
#include "fs/devices/KeyboardDevice.h"
#include "fs/devices/MouseDevice.h"
#include "fs/devices/NullDevice.h"
#include "fs/devices/UARTDevice.h"
#include "fs/devices/ZeroDevice.h"
#include "fs/tmpfs/FileSystem.h"
#include "thread/Thread.h"
#include <luna/Vector.h>

struct DeviceDescriptor
{
    SharedPtr<Device> device;
    u32 major;
    u32 minor;
    const char* name;
    mode_t mode;
};

Vector<DeviceDescriptor> g_available_devices = {};

namespace DeviceRegistry
{
    Result<SharedPtr<Device>> fetch_special_device(u32 major, u32 minor)
    {
        for (const auto& descriptor : g_available_devices)
        {
            if (descriptor.major == major && descriptor.minor == minor) return descriptor.device;
        }

        return err(ENODEV);
    }

    Result<void> create_special_device_inode(SharedPtr<VFS::FileSystem> fs, const DeviceDescriptor& descriptor)
    {
        auto inode = TRY(fs->create_device_inode(descriptor.major, descriptor.minor, descriptor.mode));
        TRY(fs->root_inode()->add_entry(inode, descriptor.name));

        return {};
    }

    Result<void> register_special_device(u32 major, u32 minor, SharedPtr<Device> device, mode_t mode)
    {
        for (const auto& descriptor : g_available_devices)
        {
            if (descriptor.major == major && descriptor.minor == minor) return err(EEXIST);
        }

        const char* name = device->device_path().chars();

#ifdef DEVICE_REGISTRY_DEBUG
        kdbgln("DeviceRegistry: registered new device type %u:%u at path /%s in devfs", major, minor, name);
#endif

        auto desc = DeviceDescriptor { .device = device, .major = major, .minor = minor, .name = name, .mode = mode };

        TRY(g_available_devices.try_append(desc));

        return {};
    }

    Result<void> init()
    {
        NullDevice::create();
        ZeroDevice::create();
        FullDevice::create();
        ConsoleDevice::create();
        FramebufferDevice::create();
        UARTDevice::create();
        MouseDevice::create();
        KeyboardDevice::create();

        return {};
    }

    dev_t next_null_device_id()
    {
        static u32 next_minor = 0;
        return luna_dev_makedev(0, next_minor++);
    }

    // FIXME: This devfs will only contain the devices registered before its creation. Otherwise, created devfs
    // instances would have to be stored using WeakPtr or something (which doesn't exist atm)...
    Result<SharedPtr<VFS::FileSystem>> create_devfs_instance()
    {
        auto fs = TRY(TmpFS::FileSystem::create());

        for (const auto& descriptor : g_available_devices) TRY(create_special_device_inode(fs, descriptor));

        return fs;
    }
}