Kernel: Extended IDE interface to allow slave device usage (#283)

The IDE Disk Controller driver has been extended to allow the secondary device on the channel to be initialised and used. A test as to whether this is working (for anyone interested) is to modify `init.cpp:87` to `auto dev_hd0 = IDEDiskDevice::create(IdeDiskDevice::DeviceType::SLAVE);`. The kernel will fail to boot, as there is no disk attached to CHANNEL 1's slave. This was born out of the fact that my FAT driver can't be tested as easily without creating a partition on `hda`.

Kernel/Devices/IDEDiskDevice.cpp

@@ -78,14 +78,15 @@
 #define ATA_REG_ALTSTATUS 0x0C
 #define ATA_REG_DEVADDRESS 0x0D
 
-NonnullRefPtr<IDEDiskDevice> IDEDiskDevice::create()
+NonnullRefPtr<IDEDiskDevice> IDEDiskDevice::create(DriveType type)
 {
-    return adopt(*new IDEDiskDevice);
+    return adopt(*new IDEDiskDevice(type));
 }
 
-IDEDiskDevice::IDEDiskDevice()
+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);
@@ -195,6 +196,9 @@ void IDEDiskDevice::initialize()
     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;
@@ -204,8 +208,12 @@ void IDEDiskDevice::initialize()
 
     enable_irq();
 
-    IO::out8(0x1F6, 0xA0); // 0xB0 for 2nd device
-    IO::out8(0x3F6, 0xA0); // 0xB0 for 2nd device
+    u8 devsel = 0xA0;
+    if (is_slave())
+        devsel |= 0x10;
+
+    IO::out8(0x1F6, devsel);
+    IO::out8(0x3F6, devsel);
     IO::out8(m_io_base + ATA_REG_COMMAND, ATA_CMD_IDENTIFY);
 
     enable_irq();
@@ -290,9 +298,12 @@ bool IDEDiskDevice::read_sectors_with_dma(u32 lba, u16 count, u8* outbuf)
         ;
 
     bool is_slave = false;
+    u8 devsel = 0xe0;
+    if (is_slave())
+        devsel |= 0x10;
 
     IO::out8(m_io_base + ATA_REG_CONTROL, 0);
-    IO::out8(m_io_base + ATA_REG_HDDEVSEL, 0xe0 | (is_slave << 4));
+    IO::out8(m_io_base + ATA_REG_HDDEVSEL, devsel | (is_slave << 4));
     wait_400ns(m_io_base);
 
     IO::out8(m_io_base + ATA_REG_FEATURES, 0);
@@ -351,11 +362,15 @@ bool IDEDiskDevice::read_sectors(u32 start_sector, u16 count, u8* outbuf)
     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, 0xe0 | ((start_sector >> 24) & 0xf)); // 0xf0 for 2nd device
+    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))
@@ -413,9 +428,12 @@ bool IDEDiskDevice::write_sectors_with_dma(u32 lba, u16 count, const u8* inbuf)
         ;
 
     bool is_slave = false;
+    u8 devsel = 0xe0;
+    if (is_slave())
+        devsel |= 0x10;
 
     IO::out8(m_io_base + ATA_REG_CONTROL, 0);
-    IO::out8(m_io_base + ATA_REG_HDDEVSEL, 0xe0 | (is_slave << 4));
+    IO::out8(m_io_base + ATA_REG_HDDEVSEL, devsel | (is_slave << 4));
     wait_400ns(m_io_base);
 
     IO::out8(m_io_base + ATA_REG_FEATURES, 0);
@@ -471,11 +489,15 @@ bool IDEDiskDevice::write_sectors(u32 start_sector, u16 count, const u8* data)
 
     //dbgprintf("IDEDiskDevice: Writing %u sector(s) @ LBA %u\n", count, start_sector);
 
+    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, 0xe0 | ((start_sector >> 24) & 0xf)); // 0xf0 for 2nd device
+    IO::out8(m_io_base + ATA_REG_HDDEVSEL, devsel | ((start_sector >> 24) & 0xf));
 
     IO::out8(0x3F6, 0x08);
 
@@ -502,3 +524,8 @@ 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;
+}

Kernel/Devices/IDEDiskDevice.h

@@ -18,7 +18,18 @@ class IDEDiskDevice final : public IRQHandler
     , public DiskDevice {
     AK_MAKE_ETERNAL
 public:
-    static NonnullRefPtr<IDEDiskDevice> create();
+
+    // 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
+    };
+
+public:
+    static NonnullRefPtr<IDEDiskDevice> create(DriveType type);
     virtual ~IDEDiskDevice() override;
 
     // ^DiskDevice
@@ -29,7 +40,7 @@ public:
     virtual bool write_blocks(unsigned index, u16 count, const u8*) override;
 
 protected:
-    IDEDiskDevice();
+    explicit IDEDiskDevice(DriveType);
 
 private:
     // ^IRQHandler
@@ -45,6 +56,8 @@ private:
     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 };
@@ -53,6 +66,7 @@ private:
     volatile bool m_interrupted { false };
     volatile u8 m_device_error { 0 };
 
+    DriveType m_drive_type { DriveType::MASTER };
     PCI::Address m_pci_address;
     PhysicalRegionDescriptor m_prdt;
     RefPtr<PhysicalPage> m_dma_buffer_page;

Kernel/init.cpp

@@ -84,7 +84,7 @@ VFS* vfs;
         hang();
     }
 
-    auto dev_hd0 = IDEDiskDevice::create();
+    auto dev_hd0 = IDEDiskDevice::create(IDEDiskDevice::DriveType::MASTER);
 
     NonnullRefPtr<DiskDevice> root_dev = dev_hd0.copy_ref();