Storage Drivers

Location: kernel/drivers/ahci.asm, kernel/drivers/nvme.asm, kernel/drivers/usb_storage.asm, kernel/drivers/scsi.asm, kernel/drivers/cddvd.asm
Type: Kernel Drivers (Assembly)
Status: ✅ Fully Implemented

Overview

The FreeWorld OS storage driver system provides comprehensive support for all major storage interfaces, including AHCI/SATA, NVMe, USB storage, SCSI, and CD/DVD drives.

AHCI/SATA Driver

File: kernel/drivers/ahci.asm

Full implementation of the Advanced Host Controller Interface (AHCI) for SATA devices.

Features

  • AHCI controller initialization and configuration
  • Port enumeration (up to 32 ports per controller)
  • Device type detection (ATA, ATAPI, SEMB, PM)
  • Native Command Queuing (NCQ)
  • DMA transfers
  • Device identification (IDENTIFY command)
  • LBA48 support (large disk support)
  • Read/write operations
  • Error handling and recovery

API

  • ahci_init() - Initialize AHCI controller
  • ahci_read_sectors() - Read sectors from port
  • ahci_write_sectors() - Write sectors to port
  • ahci_find_controller() - Find controller by PCI device

NVMe Driver

File: kernel/drivers/nvme.asm

Complete implementation of Non-Volatile Memory Express (NVMe) for modern SSDs.

Features

  • NVMe controller initialization
  • Admin queue support (1024 entries)
  • I/O queue support (up to 16 queues)
  • Command submission and completion
  • Multiple namespace support (up to 32 namespaces)
  • Controller identification
  • Namespace identification
  • LBA64 support (very large disk support)
  • Read/write operations

API

  • nvme_init() - Initialize NVMe controller
  • nvme_read_sectors() - Read sectors from namespace
  • nvme_write_sectors() - Write sectors to namespace

USB Storage Driver

File: kernel/drivers/usb_storage.asm

USB Mass Storage Class driver with Bulk-Only Transport (BOT) protocol support.

Features

  • USB Mass Storage Class detection
  • Bulk-Only Transport (BOT) protocol
  • SCSI command passthrough
  • Multiple LUN support (up to 8 LUNs)
  • Device identification (INQUIRY)
  • Capacity reading (READ CAPACITY)
  • Read/write operations
  • Command Block Wrapper (CBW) handling
  • Command Status Wrapper (CSW) handling

API

  • usb_storage_init() - Initialize USB storage device
  • usb_storage_read_sectors() - Read sectors from LUN
  • usb_storage_write_sectors() - Write sectors to LUN

SCSI Driver

File: kernel/drivers/scsi.asm

SCSI command set implementation with support for multiple controller types.

Features

  • SCSI command set implementation
  • Multiple controller type support (AHCI, USB, NVMe, ATA)
  • Command routing to appropriate controller
  • INQUIRY command support
  • READ CAPACITY command support
  • Read/write operations

Controller Types

  • AHCI - SATA devices via AHCI
  • USB - USB storage devices
  • NVMe - NVMe SSDs
  • ATA - Legacy ATA devices

API

  • scsi_init() - Initialize SCSI device
  • scsi_read_sectors() - Read sectors via SCSI
  • scsi_write_sectors() - Write sectors via SCSI

CD/DVD Driver

File: kernel/drivers/cddvd.asm

ATAPI-based driver for optical disc drives (CD, DVD, Blu-ray).

Features

  • ATAPI device detection
  • Drive type detection (CD, DVD, Blu-ray)
  • Disc type detection (CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-R, DVD-RW, DVD-RAM, BD-ROM, BD-R, BD-RE)
  • Disc presence detection
  • Table of Contents (TOC) reading
  • Capacity reading
  • Track information
  • Read operations (2048-byte sectors)
  • Eject/close tray support

API

  • cddvd_init() - Initialize CD/DVD drive
  • cddvd_read_sectors() - Read sectors from disc
  • cddvd_eject() - Eject disc
  • cddvd_close_tray() - Close tray

Implementation Statistics

Total Lines of Code: ~3,448 lines

  • AHCI/SATA: ~1,200 lines
  • NVMe: ~900 lines
  • USB Storage: ~800 lines
  • SCSI: ~300 lines
  • CD/DVD: ~250 lines

Integration

All storage drivers are integrated with:

  • Kernel initialization sequence
  • PCI enumeration (for AHCI, NVMe)
  • USB system (for USB storage)
  • Filesystem layer (for block device access)