Kernel/Storage: Move all ATA related code to a new subdirectory

Like what happened with the PCI and USB code, this feels like the right
thing to do because we can improve on the ATA capabilities and keep it
distinguished from the rest of the subsystem.

Kernel/Storage/ATA/ATADevice.h

@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2021, Liav A. <liavalb@hotmail.co.il>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <Kernel/Interrupts/IRQHandler.h>
+#include <Kernel/Locking/Mutex.h>
+#include <Kernel/Storage/ATA/ATAController.h>
+#include <Kernel/Storage/StorageDevice.h>
+
+namespace Kernel {
+
+class ATADevice : public StorageDevice {
+public:
+    // Note: For IDE drives, port means Primary or Secondary (0 or 1),
+    // and subport means Master or Slave (0 or 1).
+    // For SATA drives (AHCI driven HBAs), a port can be a number from 0 to 31,
+    // and subport can be a number from 0 to 14 (only 15 devices are allowed to
+    // be connected to one SATA port multiplier).
+    struct Address {
+        // FIXME: u32 for this value is wasteful, because even AHCI only support 32 ports
+        u32 port;
+        u8 subport;
+    };
+
+public:
+    virtual ~ATADevice() override;
+
+    // ^BlockDevice
+    virtual void start_request(AsyncBlockDeviceRequest&) override;
+
+    u16 ata_capabilites() const { return m_capabilities; }
+    const Address& ata_address() const { return m_ata_address; }
+
+protected:
+    ATADevice(const ATAController&, Address, unsigned, u16, u16, u64, NonnullOwnPtr<KString>);
+
+    WeakPtr<ATAController> m_controller;
+    const Address m_ata_address;
+    const u16 m_capabilities;
+};
+
+}