Kernel: Move the Storage directory to be a new directory under Devices

The Storage subsystem, like the Audio and HID subsystems, exposes Unix
device files (for example, in the /dev directory). To ensure consistency
across the repository, we should make the Storage subsystem to reside in
the Kernel/Devices directory like the two other mentioned subsystems.

Kernel/Devices/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/Devices/Storage/ATA/ATAController.h>
+#include <Kernel/Devices/Storage/StorageDevice.h>
+#include <Kernel/Interrupts/IRQHandler.h>
+#include <Kernel/Locking/Mutex.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; }
+    Address const& ata_address() const { return m_ata_address; }
+
+protected:
+    ATADevice(ATAController const&, Address, u16, u16, u64);
+
+    LockWeakPtr<ATAController> m_controller;
+    const Address m_ata_address;
+    const u16 m_capabilities;
+};
+
+}