Kernel: ATA now uses irqs instead of polling

Reading is now much slower at ~500 kB/s it was around 3 MB/s.
This is probably mostly due semaphore blocking taking atleast
until next reschedule (1 ms itervals). This will be a problem
as long as we are using only single processor.

I could try to use {READ/WRITE}_MULTIPLE commands, but since
most of the disk reads are 2 sectors (inode block size) this
will at most double the speed.

Most efficient speed up would of course be caching disk access
data and inodes overall.

kernel/include/kernel/Storage/ATABus.h

@@ -0,0 +1,68 @@
+#pragma once
+
+#include <BAN/Errors.h>
+#include <kernel/Semaphore.h>
+#include <kernel/SpinLock.h>
+#include <kernel/Storage/ATAController.h>
+
+namespace Kernel
+{
+
+	class ATADevice;
+
+	class ATABus
+	{
+	public:
+		enum class DeviceType
+		{
+			None,
+			ATA,
+			ATAPI,
+		};
+
+	public:
+		static ATABus* create(ATAController*, uint16_t base, uint16_t ctrl, uint8_t irq);
+
+		BAN::ErrorOr<void> read(ATADevice*, uint64_t, uint8_t, uint8_t*);
+		BAN::ErrorOr<void> write(ATADevice*, uint64_t, uint8_t, const uint8_t*);
+
+		ATAController* controller() { return m_controller; }
+
+		void on_irq();
+
+	private:
+		ATABus(ATAController* controller, uint16_t base, uint16_t ctrl)
+			: m_controller(controller)
+			, m_base(base)
+			, m_ctrl(ctrl)
+		{}
+		void initialize(uint8_t irq);
+
+		void select_device(const ATADevice*);
+		DeviceType identify(const ATADevice*, uint16_t*);
+
+		void block_until_irq();
+		uint8_t device_index(const ATADevice*) const;
+
+		uint8_t io_read(uint16_t);
+		void io_write(uint16_t, uint8_t);
+		void read_buffer(uint16_t, uint16_t*, size_t);
+		void write_buffer(uint16_t, const uint16_t*, size_t);
+		BAN::ErrorOr<void> wait(bool);
+		BAN::Error error();
+
+	private:
+		ATAController* m_controller;
+		const uint16_t m_base;
+		const uint16_t m_ctrl;
+		SpinLock m_lock;
+		Semaphore m_semaphore;
+
+		bool m_has_got_irq { false };
+
+		ATADevice* m_devices[2] { nullptr, nullptr };
+
+		friend class ATAController;
+	};
+
+}