Kernel: Expand PATA driver to support multiple hard drives (#365)

The previous implementation of the PIIX3/4 PATA/IDE channel driver only
supported a single drive, as the object model was wrong (the channel
inherits the IRQ, not the disk drive itself). This fixes it by 'attaching'
two `PATADiskDevices` to a `PATAChannel`, which makes more sense.

The reading/writing code is presented as is, which violates the spec
outlined by Seagate in the linked datasheet. That spec is rather old,
so it might not be 100% up to date, though may cause issues on real
hardware, so until we can actually test it, this will suffice.

6 files changed, 435 insertions, 232 deletions

diff --git a/Kernel/Devices/IDEDiskDevice.cpp b/Kernel/Devices/PATAChannel.cpp
index f9ce5daa72..8847505636 100644
--- a/Kernel/Devices/IDEDiskDevice.cpp
+++ b/Kernel/Devices/PATAChannel.cpp
@@ -1,14 +1,15 @@
-#include <Kernel/Devices/IDEDiskDevice.h>
+#include "PATADiskDevice.h"
+#include <AK/ByteBuffer.h>
+#include <Kernel/Devices/PATAChannel.h>
 #include <Kernel/FileSystem/ProcFS.h>
 #include <Kernel/IO.h>
-#include <Kernel/Arch/i386/PIC.h>
 #include <Kernel/Process.h>
-#include <Kernel/StdLib.h>
 #include <Kernel/VM/MemoryManager.h>
 
-//#define DISK_DEBUG
+#define PATA_PRIMARY_IRQ 14
+#define PATA_SECONDARY_IRQ 15
 
-#define IRQ_FIXED_DISK 14
+//#define PATA_DEBUG
 
 #define ATA_SR_BSY 0x80
 #define ATA_SR_DRDY 0x40
@@ -78,61 +79,55 @@
 #define ATA_REG_ALTSTATUS 0x0C
 #define ATA_REG_DEVADDRESS 0x0D
 
-NonnullRefPtr<IDEDiskDevice> IDEDiskDevice::create(DriveType type)
+static Lock& s_lock()
 {
-    return adopt(*new IDEDiskDevice(type));
-}
+    static Lock* lock;
+    if (!lock)
+        lock = new Lock;
 
-IDEDiskDevice::IDEDiskDevice(DriveType type)
-    : IRQHandler(IRQ_FIXED_DISK)
-    , m_io_base(0x1f0)
-    , m_drive_type(type)
-{
-    m_dma_enabled.resource() = true;
-    ProcFS::the().add_sys_bool("ide_dma", m_dma_enabled);
-    initialize();
-}
+    return *lock;
+};
 
-IDEDiskDevice::~IDEDiskDevice()
+OwnPtr<PATAChannel> PATAChannel::create(ChannelType type)
 {
+    return make<PATAChannel>(type);
 }
 
-const char* IDEDiskDevice::class_name() const
+PATAChannel::PATAChannel(ChannelType type)
+    : IRQHandler((type == ChannelType::Primary ? PATA_PRIMARY_IRQ : PATA_SECONDARY_IRQ))
+    , m_channel_number((type == ChannelType::Primary ? 0 : 1))
+    , m_io_base((type == ChannelType::Primary ? 0x1F0 : 0x170))
 {
-    return "IDEDiskDevice";
-}
+    m_dma_enabled.resource() = true;
+    ProcFS::the().add_sys_bool("ide_dma", m_dma_enabled);
 
-unsigned IDEDiskDevice::block_size() const
-{
-    return 512;
+    initialize();
+    detect_disks();
 }
 
-bool IDEDiskDevice::read_blocks(unsigned index, u16 count, u8* out)
+PATAChannel::~PATAChannel()
 {
-    if (m_bus_master_base && m_dma_enabled.resource())
-        return read_sectors_with_dma(index, count, out);
-    return read_sectors(index, count, out);
 }
 
-bool IDEDiskDevice::read_block(unsigned index, u8* out) const
+void PATAChannel::initialize()
 {
-    return const_cast<IDEDiskDevice*>(this)->read_blocks(index, 1, out);
-}
+    static const PCI::ID piix3_ide_id = { 0x8086, 0x7010 };
+    static const PCI::ID piix4_ide_id = { 0x8086, 0x7111 };
+    PCI::enumerate_all([this](const PCI::Address& address, PCI::ID id) {
+        if (id == piix3_ide_id || id == piix4_ide_id) {
+            m_pci_address = address;
+            kprintf("PIIX%u PATA Controller found!\n", id == piix3_ide_id ? 3 : 4);
+        }
+    });
 
-bool IDEDiskDevice::write_blocks(unsigned index, u16 count, const u8* data)
-{
-    if (m_bus_master_base && m_dma_enabled.resource())
-        return write_sectors_with_dma(index, count, data);
-    for (unsigned i = 0; i < count; ++i) {
-        if (!write_sectors(index + i, 1, data + i * 512))
-            return false;
+    // Let's try to set up DMA transfers.
+    if (!m_pci_address.is_null()) {
+        m_prdt.end_of_table = 0x8000;
+        PCI::enable_bus_mastering(m_pci_address);
+        m_bus_master_base = PCI::get_BAR4(m_pci_address) & 0xfffc;
+        m_dma_buffer_page = MM.allocate_supervisor_physical_page();
+        dbgprintf("PIIX Bus master IDE: I/O @ %x\n", m_bus_master_base);
     }
-    return true;
-}
-
-bool IDEDiskDevice::write_block(unsigned index, const u8* data)
-{
-    return write_blocks(index, 1, data);
 }
 
 static void print_ide_status(u8 status)
@@ -148,125 +143,114 @@ static void print_ide_status(u8 status)
         (status & ATA_SR_ERR) != 0);
 }
 
-bool IDEDiskDevice::wait_for_irq()
+bool PATAChannel::wait_for_irq()
 {
-#ifdef DISK_DEBUG
-    kprintf("disk: waiting for interrupt...\n");
+#ifdef PATA_DEBUG
+    kprintf("PATA: waiting for IRQ %d...\n", irq_number());
 #endif
-    // FIXME: Add timeout.
     while (!m_interrupted) {
         // FIXME: Put this process into a Blocked state instead, it's stupid to wake up just to check a flag.
         Scheduler::yield();
     }
-#ifdef DISK_DEBUG
-    kprintf("disk: got interrupt!\n");
+#ifdef PATA_DEBUG
+    kprintf("PATA: received IRQ %d!\n", irq_number());
 #endif
+
     return true;
 }
 
-void IDEDiskDevice::handle_irq()
+void PATAChannel::handle_irq()
 {
     u8 status = IO::in8(m_io_base + ATA_REG_STATUS);
     if (status & ATA_SR_ERR) {
         print_ide_status(status);
         m_device_error = IO::in8(m_io_base + ATA_REG_ERROR);
-        kprintf("IDEDiskDevice: Error %b!\n", m_device_error);
+        kprintf("PATADiskDevice: Error %b!\n", m_device_error);
     } else {
         m_device_error = 0;
     }
-#ifdef DISK_DEBUG
+#ifdef PATA_DEBUG
     kprintf("disk:interrupt: DRQ=%u BSY=%u DRDY=%u\n", (status & ATA_SR_DRQ) != 0, (status & ATA_SR_BSY) != 0, (status & ATA_SR_DRDY) != 0);
 #endif
     m_interrupted = true;
 }
 
-void IDEDiskDevice::initialize()
+static void wait_400ns(u16 io_base)
 {
-    static const PCI::ID piix3_ide_id = { 0x8086, 0x7010 };
-    static const PCI::ID piix4_ide_id = { 0x8086, 0x7111 };
-    PCI::enumerate_all([this](const PCI::Address& address, PCI::ID id) {
-        if (id == piix3_ide_id || id == piix4_ide_id) {
-            m_pci_address = address;
-            kprintf("PIIX%u IDE device found!\n", id == piix3_ide_id ? 3 : 4);
-        }
-    });
-
-#ifdef DISK_DEBUG
-    u8 status = IO::in8(m_io_base + ATA_REG_STATUS);
-    kprintf("initial status: ");
-    print_ide_status(status);
-
-    if (is_slave())
-        kprintf("This IDE device is the SECONDARY device on the channel!\n");
-#endif
-
-    m_interrupted = false;
-
-    while (IO::in8(m_io_base + ATA_REG_STATUS) & ATA_SR_BSY)
-        ;
-
-    enable_irq();
+    for (int i = 0; i < 4; ++i)
+        IO::in8(io_base + ATA_REG_ALTSTATUS);
+}
 
-    u8 devsel = 0xA0;
-    if (is_slave())
-        devsel |= 0x10;
+void PATAChannel::detect_disks()
+{
+    // There are only two possible disks connected to a channel
+    for (auto i = 0; i < 2; i++) {
+        enable_irq();
 
-    IO::out8(0x1F6, devsel);
-    IO::out8(0x3F6, devsel);
-    IO::out8(m_io_base + ATA_REG_COMMAND, ATA_CMD_IDENTIFY);
+        IO::out8(m_io_base + ATA_REG_HDDEVSEL, 0xA0 | (i << 4)); // First, we need to select the drive itself
 
-    enable_irq();
-    wait_for_irq();
+        // Apparently these need to be 0 before sending IDENTIFY?!
+        IO::out8(m_io_base + ATA_REG_SECCOUNT0, 0x00);
+        IO::out8(m_io_base + ATA_REG_LBA0, 0x00);
+        IO::out8(m_io_base + ATA_REG_LBA1, 0x00);
+        IO::out8(m_io_base + ATA_REG_LBA2, 0x00);
 
-    ByteBuffer wbuf = ByteBuffer::create_uninitialized(512);
-    ByteBuffer bbuf = ByteBuffer::create_uninitialized(512);
-    u8* b = bbuf.pointer();
-    u16* w = (u16*)wbuf.pointer();
-    const u16* wbufbase = (u16*)wbuf.pointer();
-
-    for (u32 i = 0; i < 256; ++i) {
-        u16 data = IO::in16(m_io_base + ATA_REG_DATA);
-        *(w++) = data;
-        *(b++) = MSB(data);
-        *(b++) = LSB(data);
-    }
+        IO::out8(m_io_base + ATA_REG_COMMAND, ATA_CMD_IDENTIFY); // Send the ATA_IDENTIFY command
 
-    // "Unpad" the device name string.
-    for (u32 i = 93; i > 54 && bbuf[i] == ' '; --i)
-        bbuf[i] = 0;
+        // Wait for the BSY flag to be reset
+        while (IO::in8(m_io_base + ATA_REG_STATUS) & ATA_SR_BSY)
+            ;
 
-    m_cylinders = wbufbase[1];
-    m_heads = wbufbase[3];
-    m_sectors_per_track = wbufbase[6];
+        if (IO::in8(m_io_base + ATA_REG_STATUS) == 0x00) {
+#ifdef PATA_DEBUG
+            kprintf("PATA: No %s disk detected!\n", (i == 0 ? "master" : "slave"));
+#endif
+            continue;
+        }
 
-    kprintf(
-        "IDEDiskDevice: Master=\"%s\", C/H/Spt=%u/%u/%u\n",
-        bbuf.pointer() + 54,
-        m_cylinders,
-        m_heads,
-        m_sectors_per_track);
+        ByteBuffer wbuf = ByteBuffer::create_uninitialized(512);
+        ByteBuffer bbuf = ByteBuffer::create_uninitialized(512);
+        u8* b = bbuf.pointer();
+        u16* w = (u16*)wbuf.pointer();
+        const u16* wbufbase = (u16*)wbuf.pointer();
+
+        for (u32 i = 0; i < 256; ++i) {
+            u16 data = IO::in16(m_io_base + ATA_REG_DATA);
+            *(w++) = data;
+            *(b++) = MSB(data);
+            *(b++) = LSB(data);
+        }
 
-    // Let's try to set up DMA transfers.
-    if (!m_pci_address.is_null()) {
-        m_prdt.end_of_table = 0x8000;
-        PCI::enable_bus_mastering(m_pci_address);
-        m_bus_master_base = PCI::get_BAR4(m_pci_address) & 0xfffc;
-        m_dma_buffer_page = MM.allocate_supervisor_physical_page();
-        dbgprintf("PIIX Bus master IDE: I/O @ %x\n", m_bus_master_base);
+        // "Unpad" the device name string.
+        for (u32 i = 93; i > 54 && bbuf[i] == ' '; --i)
+            bbuf[i] = 0;
+
+        u8 cyls = wbufbase[1];
+        u8 heads = wbufbase[3];
+        u8 spt = wbufbase[6];
+
+        kprintf(
+            "PATADiskDevice: Name=\"%s\", C/H/Spt=%u/%u/%u\n",
+            bbuf.pointer() + 54,
+            cyls,
+            heads,
+            spt);
+
+        if (i == 0) {
+            m_master = PATADiskDevice::create(*this, PATADiskDevice::DriveType::Master);
+            m_master->set_drive_geometry(cyls, heads, spt);
+        } else {
+            m_slave = PATADiskDevice::create(*this, PATADiskDevice::DriveType::Slave);
+            m_slave->set_drive_geometry(cyls, heads, spt);
+        }
     }
 }
 
-static void wait_400ns(u16 io_base)
+bool PATAChannel::ata_read_sectors_with_dma(u32 lba, u16 count, u8* outbuf, bool slave_request)
 {
-    for (int i = 0; i < 4; ++i)
-        IO::in8(io_base + ATA_REG_ALTSTATUS);
-}
-
-bool IDEDiskDevice::read_sectors_with_dma(u32 lba, u16 count, u8* outbuf)
-{
-    LOCKER(m_lock);
-#ifdef DISK_DEBUG
-    dbgprintf("%s(%u): IDEDiskDevice::read_sectors_with_dma (%u x%u) -> %p\n",
+    LOCKER(s_lock());
+#ifdef PATA_DEBUG
+    dbgprintf("%s(%u): PATADiskDevice::read_sectors_with_dma (%u x%u) -> %p\n",
         current->process().name().characters(),
         current->pid(), lba, count, outbuf);
 #endif
@@ -297,11 +281,11 @@ bool IDEDiskDevice::read_sectors_with_dma(u32 lba, u16 count, u8* outbuf)
         ;
 
     u8 devsel = 0xe0;
-    if (is_slave())
+    if (slave_request)
         devsel |= 0x10;
 
     IO::out8(m_io_base + ATA_REG_CONTROL, 0);
-    IO::out8(m_io_base + ATA_REG_HDDEVSEL, devsel | (is_slave() << 4));
+    IO::out8(m_io_base + ATA_REG_HDDEVSEL, devsel | (static_cast<u8>(slave_request) << 4));
     wait_400ns(m_io_base);
 
     IO::out8(m_io_base + ATA_REG_FEATURES, 0);
@@ -341,62 +325,11 @@ bool IDEDiskDevice::read_sectors_with_dma(u32 lba, u16 count, u8* outbuf)
     return true;
 }
 
-bool IDEDiskDevice::read_sectors(u32 start_sector, u16 count, u8* outbuf)
+bool PATAChannel::ata_write_sectors_with_dma(u32 lba, u16 count, const u8* inbuf, bool slave_request)
 {
-    ASSERT(count <= 256);
-    LOCKER(m_lock);
-#ifdef DISK_DEBUG
-    dbgprintf("%s: Disk::read_sectors request (%u sector(s) @ %u)\n",
-        current->process().name().characters(),
-        count,
-        start_sector);
-#endif
-    disable_irq();
-
-    while (IO::in8(m_io_base + ATA_REG_STATUS) & ATA_SR_BSY)
-        ;
-
-#ifdef DISK_DEBUG
-    kprintf("IDEDiskDevice: Reading %u sector(s) @ LBA %u\n", count, start_sector);
-#endif
-
-    u8 devsel = 0xe0;
-    if (is_slave())
-        devsel |= 0x10;
-
-    IO::out8(m_io_base + ATA_REG_SECCOUNT0, count == 256 ? 0 : LSB(count));
-    IO::out8(m_io_base + ATA_REG_LBA0, start_sector & 0xff);
-    IO::out8(m_io_base + ATA_REG_LBA1, (start_sector >> 8) & 0xff);
-    IO::out8(m_io_base + ATA_REG_LBA2, (start_sector >> 16) & 0xff);
-    IO::out8(m_io_base + ATA_REG_HDDEVSEL, devsel | ((start_sector >> 24) & 0xf));
-
-    IO::out8(0x3F6, 0x08);
-    while (!(IO::in8(m_io_base + ATA_REG_STATUS) & ATA_SR_DRDY))
-        ;
-
-    IO::out8(m_io_base + ATA_REG_COMMAND, ATA_CMD_READ_PIO);
-    m_interrupted = false;
-    enable_irq();
-    wait_for_irq();
-
-    if (m_device_error)
-        return false;
-
-    u8 status = IO::in8(m_io_base + ATA_REG_STATUS);
-    ASSERT(status & ATA_SR_DRQ);
-#ifdef DISK_DEBUG
-    kprintf("Retrieving %u bytes (status=%b), outbuf=%p...\n", count * 512, status, outbuf);
-#endif
-
-    IO::repeated_in16(m_io_base + ATA_REG_DATA, outbuf, count * 256);
-    return true;
-}
-
-bool IDEDiskDevice::write_sectors_with_dma(u32 lba, u16 count, const u8* inbuf)
-{
-    LOCKER(m_lock);
-#ifdef DISK_DEBUG
-    dbgprintf("%s(%u): IDEDiskDevice::write_sectors_with_dma (%u x%u) <- %p\n",
+    LOCKER(s_lock());
+#ifdef PATA_DEBUG
+    dbgprintf("%s(%u): PATADiskDevice::write_sectors_with_dma (%u x%u) <- %p\n",
         current->process().name().characters(),
         current->pid(), lba, count, inbuf);
 #endif
@@ -426,11 +359,11 @@ bool IDEDiskDevice::write_sectors_with_dma(u32 lba, u16 count, const u8* inbuf)
         ;
 
     u8 devsel = 0xe0;
-    if (is_slave())
+    if (slave_request)
         devsel |= 0x10;
 
     IO::out8(m_io_base + ATA_REG_CONTROL, 0);
-    IO::out8(m_io_base + ATA_REG_HDDEVSEL, devsel | (is_slave() << 4));
+    IO::out8(m_io_base + ATA_REG_HDDEVSEL, devsel | (static_cast<u8>(slave_request) << 4));
     wait_400ns(m_io_base);
 
     IO::out8(m_io_base + ATA_REG_FEATURES, 0);
@@ -468,12 +401,63 @@ bool IDEDiskDevice::write_sectors_with_dma(u32 lba, u16 count, const u8* inbuf)
     return true;
 }
 
-bool IDEDiskDevice::write_sectors(u32 start_sector, u16 count, const u8* data)
+bool PATAChannel::ata_read_sectors(u32 start_sector, u16 count, u8* outbuf, bool slave_request)
 {
     ASSERT(count <= 256);
-    LOCKER(m_lock);
-#ifdef DISK_DEBUG
-    dbgprintf("%s(%u): IDEDiskDevice::write_sectors request (%u sector(s) @ %u)\n",
+    LOCKER(s_lock());
+#ifdef PATA_DEBUG
+    dbgprintf("%s: Disk::read_sectors request (%u sector(s) @ %u)\n",
+        current->process().name().characters(),
+        count,
+        start_sector);
+#endif
+    disable_irq();
+
+    while (IO::in8(m_io_base + ATA_REG_STATUS) & ATA_SR_BSY)
+        ;
+
+#ifdef PATA_DEBUG
+    kprintf("PATADiskDevice: Reading %u sector(s) @ LBA %u\n", count, start_sector);
+#endif
+
+    u8 devsel = 0xe0;
+    if (slave_request)
+        devsel |= 0x10;
+
+    IO::out8(m_io_base + ATA_REG_SECCOUNT0, count == 256 ? 0 : LSB(count));
+    IO::out8(m_io_base + ATA_REG_LBA0, start_sector & 0xff);
+    IO::out8(m_io_base + ATA_REG_LBA1, (start_sector >> 8) & 0xff);
+    IO::out8(m_io_base + ATA_REG_LBA2, (start_sector >> 16) & 0xff);
+    IO::out8(m_io_base + ATA_REG_HDDEVSEL, devsel | ((start_sector >> 24) & 0xf));
+
+    IO::out8(0x3F6, 0x08);
+    while (!(IO::in8(m_io_base + ATA_REG_STATUS) & ATA_SR_DRDY))
+        ;
+
+    IO::out8(m_io_base + ATA_REG_COMMAND, ATA_CMD_READ_PIO);
+    m_interrupted = false;
+    enable_irq();
+    wait_for_irq();
+
+    if (m_device_error)
+        return false;
+
+    u8 status = IO::in8(m_io_base + ATA_REG_STATUS);
+    ASSERT(status & ATA_SR_DRQ);
+#ifdef PATA_DEBUG
+    kprintf("Retrieving %u bytes (status=%b), outbuf=%p...\n", count * 512, status, outbuf);
+#endif
+
+    IO::repeated_in16(m_io_base + ATA_REG_DATA, outbuf, count * 256);
+    return true;
+}
+
+bool PATAChannel::ata_write_sectors(u32 start_sector, u16 count, const u8* inbuf, bool slave_request)
+{
+    ASSERT(count <= 256);
+    LOCKER(s_lock());
+#ifdef PATA_DEBUG
+    dbgprintf("%s(%u): PATADiskDevice::write_sectors request (%u sector(s) @ %u)\n",
         current->process().name().characters(),
         current->pid(),
         count,
@@ -484,10 +468,10 @@ bool IDEDiskDevice::write_sectors(u32 start_sector, u16 count, const u8* data)
     while (IO::in8(m_io_base + ATA_REG_STATUS) & ATA_SR_BSY)
         ;
 
-    //dbgprintf("IDEDiskDevice: Writing %u sector(s) @ LBA %u\n", count, start_sector);
+    //dbgprintf("PATADiskDevice: Writing %u sector(s) @ LBA %u\n", count, start_sector);
 
     u8 devsel = 0xe0;
-    if (is_slave())
+    if (slave_request)
         devsel |= 0x10;
 
     IO::out8(m_io_base + ATA_REG_SECCOUNT0, count == 256 ? 0 : LSB(count));
@@ -505,7 +489,7 @@ bool IDEDiskDevice::write_sectors(u32 start_sector, u16 count, const u8* data)
 
     u8 status = IO::in8(m_io_base + ATA_REG_STATUS);
     ASSERT(status & ATA_SR_DRQ);
-    IO::repeated_out16(m_io_base + ATA_REG_DATA, data, count * 256);
+    IO::repeated_out16(m_io_base + ATA_REG_DATA, inbuf, count * 256);
 
     m_interrupted = false;
     enable_irq();
@@ -521,8 +505,3 @@ bool IDEDiskDevice::write_sectors(u32 start_sector, u16 count, const u8* data)
 
     return !m_device_error;
 }
-
-bool IDEDiskDevice::is_slave() const
-{
-    return m_drive_type == DriveType::SLAVE;
-}
diff --git a/Kernel/Devices/PATAChannel.h b/Kernel/Devices/PATAChannel.h
new file mode 100644
index 0000000000..8bf28adf1a
--- /dev/null
+++ b/Kernel/Devices/PATAChannel.h
@@ -0,0 +1,72 @@
+//
+// Parallel ATA (PATA) controller driver
+//
+// This driver describes a logical PATA Channel. Each channel can connect up to 2
+// IDE Hard Disk Drives. The drives themselves can be either the master drive (hd0)
+// or the slave drive (hd1).
+//
+// More information about the ATA spec for PATA can be found here:
+//      ftp://ftp.seagate.com/acrobat/reference/111-1c.pdf
+//
+#pragma once
+
+#include <AK/OwnPtr.h>
+#include <AK/RefPtr.h>
+#include <Kernel/IRQHandler.h>
+#include <Kernel/Lock.h>
+#include <Kernel/PCI.h>
+#include <Kernel/VM/PhysicalAddress.h>
+#include <Kernel/VM/PhysicalPage.h>
+
+struct PhysicalRegionDescriptor {
+    PhysicalAddress offset;
+    u16 size { 0 };
+    u16 end_of_table { 0 };
+};
+
+class PATADiskDevice;
+class PATAChannel final : public IRQHandler {
+    friend class PATADiskDevice;
+    AK_MAKE_ETERNAL
+public:
+    enum class ChannelType : u8 {
+        Primary,
+        Secondary
+    };
+
+public:
+    static OwnPtr<PATAChannel> create(ChannelType type);
+    explicit PATAChannel(ChannelType);
+    virtual ~PATAChannel() override;
+
+    RefPtr<PATADiskDevice> master_device() { return m_master; };
+    RefPtr<PATADiskDevice> slave_device() { return m_slave; };
+
+private:
+    //^ IRQHandler
+    virtual void handle_irq() override;
+
+    void initialize();
+    void detect_disks();
+
+    bool wait_for_irq();
+    bool ata_read_sectors_with_dma(u32, u16, u8*, bool);
+    bool ata_write_sectors_with_dma(u32, u16, const u8*, bool);
+    bool ata_read_sectors(u32, u16, u8*, bool);
+    bool ata_write_sectors(u32, u16, const u8*, bool);
+
+    // Data members
+    u8 m_channel_number { 0 }; // Channel number. 0 = master, 1 = slave
+    u16 m_io_base { 0x1F0 };
+    volatile u8 m_device_error { 0 };
+    volatile bool m_interrupted { false };
+
+    PCI::Address m_pci_address;
+    PhysicalRegionDescriptor m_prdt;
+    RefPtr<PhysicalPage> m_dma_buffer_page;
+    u16 m_bus_master_base { 0 };
+    Lockable<bool> m_dma_enabled;
+
+    RefPtr<PATADiskDevice> m_master;
+    RefPtr<PATADiskDevice> m_slave;
+};
diff --git a/Kernel/Devices/PATADiskDevice.cpp b/Kernel/Devices/PATADiskDevice.cpp
new file mode 100644
index 0000000000..69b50e08c2
--- /dev/null
+++ b/Kernel/Devices/PATADiskDevice.cpp
@@ -0,0 +1,164 @@
+#include "PATADiskDevice.h"
+#include <Kernel/Arch/i386/PIC.h>
+#include <Kernel/FileSystem/ProcFS.h>
+#include <Kernel/IO.h>
+#include <Kernel/Process.h>
+#include <Kernel/StdLib.h>
+#include <Kernel/VM/MemoryManager.h>
+
+//#define DISK_DEBUG
+
+#define IRQ_FIXED_DISK 14
+
+#define ATA_SR_BSY 0x80
+#define ATA_SR_DRDY 0x40
+#define ATA_SR_DF 0x20
+#define ATA_SR_DSC 0x10
+#define ATA_SR_DRQ 0x08
+#define ATA_SR_CORR 0x04
+#define ATA_SR_IDX 0x02
+#define ATA_SR_ERR 0x01
+
+#define ATA_ER_BBK 0x80
+#define ATA_ER_UNC 0x40
+#define ATA_ER_MC 0x20
+#define ATA_ER_IDNF 0x10
+#define ATA_ER_MCR 0x08
+#define ATA_ER_ABRT 0x04
+#define ATA_ER_TK0NF 0x02
+#define ATA_ER_AMNF 0x01
+
+#define ATA_CMD_READ_PIO 0x20
+#define ATA_CMD_READ_PIO_EXT 0x24
+#define ATA_CMD_READ_DMA 0xC8
+#define ATA_CMD_READ_DMA_EXT 0x25
+#define ATA_CMD_WRITE_PIO 0x30
+#define ATA_CMD_WRITE_PIO_EXT 0x34
+#define ATA_CMD_WRITE_DMA 0xCA
+#define ATA_CMD_WRITE_DMA_EXT 0x35
+#define ATA_CMD_CACHE_FLUSH 0xE7
+#define ATA_CMD_CACHE_FLUSH_EXT 0xEA
+#define ATA_CMD_PACKET 0xA0
+#define ATA_CMD_IDENTIFY_PACKET 0xA1
+#define ATA_CMD_IDENTIFY 0xEC
+
+#define ATAPI_CMD_READ 0xA8
+#define ATAPI_CMD_EJECT 0x1B
+
+#define ATA_IDENT_DEVICETYPE 0
+#define ATA_IDENT_CYLINDERS 2
+#define ATA_IDENT_HEADS 6
+#define ATA_IDENT_SECTORS 12
+#define ATA_IDENT_SERIAL 20
+#define ATA_IDENT_MODEL 54
+#define ATA_IDENT_CAPABILITIES 98
+#define ATA_IDENT_FIELDVALID 106
+#define ATA_IDENT_MAX_LBA 120
+#define ATA_IDENT_COMMANDSETS 164
+#define ATA_IDENT_MAX_LBA_EXT 200
+
+#define IDE_ATA 0x00
+#define IDE_ATAPI 0x01
+
+#define ATA_REG_DATA 0x00
+#define ATA_REG_ERROR 0x01
+#define ATA_REG_FEATURES 0x01
+#define ATA_REG_SECCOUNT0 0x02
+#define ATA_REG_LBA0 0x03
+#define ATA_REG_LBA1 0x04
+#define ATA_REG_LBA2 0x05
+#define ATA_REG_HDDEVSEL 0x06
+#define ATA_REG_COMMAND 0x07
+#define ATA_REG_STATUS 0x07
+#define ATA_REG_SECCOUNT1 0x08
+#define ATA_REG_LBA3 0x09
+#define ATA_REG_LBA4 0x0A
+#define ATA_REG_LBA5 0x0B
+#define ATA_REG_CONTROL 0x0C
+#define ATA_REG_ALTSTATUS 0x0C
+#define ATA_REG_DEVADDRESS 0x0D
+
+NonnullRefPtr<PATADiskDevice> PATADiskDevice::create(PATAChannel& channel, DriveType type)
+{
+    return adopt(*new PATADiskDevice(channel, type));
+}
+
+PATADiskDevice::PATADiskDevice(PATAChannel& channel, DriveType type)
+    : m_drive_type(type)
+    , m_channel(channel)
+{
+}
+
+PATADiskDevice::~PATADiskDevice()
+{
+}
+
+const char* PATADiskDevice::class_name() const
+{
+    return "PATADiskDevice";
+}
+
+unsigned PATADiskDevice::block_size() const
+{
+    return 512;
+}
+
+bool PATADiskDevice::read_blocks(unsigned index, u16 count, u8* out)
+{
+    if (m_channel.m_bus_master_base && m_channel.m_dma_enabled.resource())
+        return read_sectors_with_dma(index, count, out);
+    return read_sectors(index, count, out);
+}
+
+bool PATADiskDevice::read_block(unsigned index, u8* out) const
+{
+    return const_cast<PATADiskDevice*>(this)->read_blocks(index, 1, out);
+}
+
+bool PATADiskDevice::write_blocks(unsigned index, u16 count, const u8* data)
+{
+    if (m_channel.m_bus_master_base && m_channel.m_dma_enabled.resource())
+        return write_sectors_with_dma(index, count, data);
+    for (unsigned i = 0; i < count; ++i) {
+        if (!write_sectors(index + i, 1, data + i * 512))
+            return false;
+    }
+    return true;
+}
+
+bool PATADiskDevice::write_block(unsigned index, const u8* data)
+{
+    return write_blocks(index, 1, data);
+}
+
+void PATADiskDevice::set_drive_geometry(u16 cyls, u16 heads, u16 spt)
+{
+    m_cylinders = cyls;
+    m_heads = heads;
+    m_sectors_per_track = spt;
+}
+
+bool PATADiskDevice::read_sectors_with_dma(u32 lba, u16 count, u8* outbuf)
+{
+    return m_channel.ata_read_sectors_with_dma(lba, count, outbuf, is_slave());
+}
+
+bool PATADiskDevice::read_sectors(u32 start_sector, u16 count, u8* outbuf)
+{
+    return m_channel.ata_read_sectors(start_sector, count, outbuf, is_slave());
+}
+
+bool PATADiskDevice::write_sectors_with_dma(u32 lba, u16 count, const u8* inbuf)
+{
+    return m_channel.ata_write_sectors_with_dma(lba, count, inbuf, is_slave());
+}
+
+bool PATADiskDevice::write_sectors(u32 start_sector, u16 count, const u8* inbuf)
+{
+    return m_channel.ata_write_sectors(start_sector, count, inbuf, is_slave());
+}
+
+bool PATADiskDevice::is_slave() const
+{
+    return m_drive_type == DriveType::Slave;
+}
diff --git a/Kernel/Devices/IDEDiskDevice.h b/Kernel/Devices/PATADiskDevice.h
index 5c55cee5bc..3d3c4928d4 100644
--- a/Kernel/Devices/IDEDiskDevice.h
+++ b/Kernel/Devices/PATADiskDevice.h
@@ -1,36 +1,33 @@
+//
+// A Disk Device Connected to a PATA Channel
+//
+//
 #pragma once
 
 #include <AK/RefPtr.h>
 #include <Kernel/Devices/DiskDevice.h>
+#include <Kernel/Devices/PATAChannel.h>
 #include <Kernel/IRQHandler.h>
 #include <Kernel/Lock.h>
 #include <Kernel/PCI.h>
 #include <Kernel/VM/PhysicalAddress.h>
 #include <Kernel/VM/PhysicalPage.h>
 
-struct PhysicalRegionDescriptor {
-    PhysicalAddress offset;
-    u16 size { 0 };
-    u16 end_of_table { 0 };
-};
-
-class IDEDiskDevice final : public IRQHandler
-    , public DiskDevice {
+class PATADiskDevice final : public DiskDevice {
     AK_MAKE_ETERNAL
 public:
-
     // Type of drive this IDEDiskDevice is on the ATA channel.
     //
     // Each PATA channel can contain only two devices, which (I think) are
     // jumper selectable on the drive itself by shorting two pins.
     enum class DriveType : u8 {
-        MASTER,
-        SLAVE
+        Master,
+        Slave
     };
 
 public:
-    static NonnullRefPtr<IDEDiskDevice> create(DriveType type);
-    virtual ~IDEDiskDevice() override;
+    static NonnullRefPtr<PATADiskDevice> create(PATAChannel&, DriveType);
+    virtual ~PATADiskDevice() override;
 
     // ^DiskDevice
     virtual unsigned block_size() const override;
@@ -39,37 +36,27 @@ public:
     virtual bool read_blocks(unsigned index, u16 count, u8*) override;
     virtual bool write_blocks(unsigned index, u16 count, const u8*) override;
 
+    void set_drive_geometry(u16, u16, u16);
+
 protected:
-    explicit IDEDiskDevice(DriveType);
+    explicit PATADiskDevice(PATAChannel&, DriveType);
 
 private:
-    // ^IRQHandler
-    virtual void handle_irq() override;
-
     // ^DiskDevice
     virtual const char* class_name() const override;
 
-    void initialize();
     bool wait_for_irq();
     bool read_sectors_with_dma(u32 lba, u16 count, u8*);
     bool write_sectors_with_dma(u32 lba, u16 count, const u8*);
     bool read_sectors(u32 lba, u16 count, u8* buffer);
     bool write_sectors(u32 lba, u16 count, const u8* data);
-
     bool is_slave() const;
 
     Lock m_lock { "IDEDiskDevice" };
     u16 m_cylinders { 0 };
     u16 m_heads { 0 };
     u16 m_sectors_per_track { 0 };
-    u16 m_io_base { 0 };
-    volatile bool m_interrupted { false };
-    volatile u8 m_device_error { 0 };
+    DriveType m_drive_type { DriveType::Master };
 
-    DriveType m_drive_type { DriveType::MASTER };
-    PCI::Address m_pci_address;
-    PhysicalRegionDescriptor m_prdt;
-    RefPtr<PhysicalPage> m_dma_buffer_page;
-    u16 m_bus_master_base { 0 };
-    Lockable<bool> m_dma_enabled;
+    PATAChannel& m_channel;
 };
diff --git a/Kernel/Makefile b/Kernel/Makefile
index c302147db7..65325a1ad0 100644
--- a/Kernel/Makefile
+++ b/Kernel/Makefile
@@ -13,7 +13,8 @@ KERNEL_OBJS = \
        CMOS.o \
        Arch/i386/PIC.o \
        Syscall.o \
-       Devices/IDEDiskDevice.o \
+       Devices/PATAChannel.o \
+       Devices/PATADiskDevice.o \
        Devices/FloppyDiskDevice.o \
        VM/MemoryManager.o \
        VM/Region.o \
diff --git a/Kernel/init.cpp b/Kernel/init.cpp
index 1b7c243311..2b22bfe29f 100644
--- a/Kernel/init.cpp
+++ b/Kernel/init.cpp
@@ -1,3 +1,4 @@
+#include "Devices/PATADiskDevice.h"
 #include "KSyms.h"
 #include "Process.h"
 #include "RTC.h"
@@ -13,13 +14,13 @@
 #include <Kernel/Devices/DiskPartition.h>
 #include <Kernel/Devices/FloppyDiskDevice.h>
 #include <Kernel/Devices/FullDevice.h>
-#include <Kernel/Devices/IDEDiskDevice.h>
 #include <Kernel/Devices/KeyboardDevice.h>
 #include <Kernel/Devices/MBRPartitionTable.h>
 #include <Kernel/Devices/NullDevice.h>
+#include <Kernel/Devices/PATAChannel.h>
 #include <Kernel/Devices/PS2MouseDevice.h>
-#include <Kernel/Devices/SB16.h>
 #include <Kernel/Devices/RandomDevice.h>
+#include <Kernel/Devices/SB16.h>
 #include <Kernel/Devices/SerialDevice.h>
 #include <Kernel/Devices/ZeroDevice.h>
 #include <Kernel/FileSystem/DevPtsFS.h>
@@ -68,9 +69,8 @@ VFS* vfs;
         hang();
     }
 
-    auto dev_hd0 = IDEDiskDevice::create(IDEDiskDevice::DriveType::MASTER);
-
-    NonnullRefPtr<DiskDevice> root_dev = dev_hd0;
+    auto pata0 = PATAChannel::create(PATAChannel::ChannelType::Primary);
+    NonnullRefPtr<DiskDevice> root_dev = *pata0->master_device();
 
     root = root.substring(strlen("/dev/hda"), root.length() - strlen("/dev/hda"));