Kernel: Implement basic AC97 driver

kernel/include/kernel/Audio/AC97/Controller.h

@@ -0,0 +1,51 @@
+#pragma once
+
+#include <kernel/Audio/Controller.h>
+#include <kernel/Memory/DMARegion.h>
+
+namespace Kernel
+{
+
+	class AC97AudioController : public AudioController, public Interruptable
+	{
+	public:
+		static BAN::ErrorOr<BAN::RefPtr<AC97AudioController>> create(PCI::Device& pci_device);
+
+		void handle_irq() override;
+
+	protected:
+		void handle_new_data() override;
+
+		uint32_t get_channels() const override { return 2; }
+		uint32_t get_sample_rate() const override { return 48000; }
+
+	private:
+		AC97AudioController(PCI::Device& pci_device)
+			: m_pci_device(pci_device)
+		{ }
+
+		BAN::ErrorOr<void> initialize();
+		BAN::ErrorOr<void> initialize_bld();
+		BAN::ErrorOr<void> initialize_interrupts();
+
+		void queue_samples_to_bld();
+
+	private:
+		static constexpr size_t m_bdl_entries = 32;
+		static constexpr size_t m_samples_per_entry = 0x1000;
+
+		// We only store samples in 2 BDL entries at a time to reduce the amount of samples queued.
+		// This is to reduce latency as you cannot remove data already passed to the BDLs
+		static constexpr size_t m_used_bdl_entries = 2;
+
+		PCI::Device& m_pci_device;
+		BAN::UniqPtr<PCI::BarRegion> m_mixer;
+		BAN::UniqPtr<PCI::BarRegion> m_bus_master;
+
+		BAN::UniqPtr<DMARegion> m_bdl_region;
+
+		uint32_t m_bdl_tail { 0 };
+		uint32_t m_bdl_head { 0 };
+	};
+
+}

kernel/include/kernel/Audio/AC97/Definitions.h

@@ -0,0 +1,15 @@
+#pragma once
+
+#include <stdint.h>
+
+namespace Kernel::AC97
+{
+
+	struct BufferDescriptorListEntry
+	{
+		uint32_t address;
+		uint16_t samples;
+		uint16_t flags; // bit 14: last entry, bit 15: IOC
+	};
+
+}

kernel/include/kernel/Audio/Controller.h

@@ -0,0 +1,48 @@
+#pragma once
+
+#include <kernel/Device/Device.h>
+#include <kernel/PCI.h>
+
+namespace Kernel
+{
+
+	class AudioController : public CharacterDevice
+	{
+	public:
+		static BAN::ErrorOr<BAN::RefPtr<AudioController>> create(PCI::Device& pci_device);
+
+		dev_t rdev() const override { return m_rdev; }
+		BAN::StringView name() const override { return m_name; }
+
+	protected:
+		AudioController();
+
+		virtual void handle_new_data() = 0;
+
+		virtual uint32_t get_channels() const = 0;
+		virtual uint32_t get_sample_rate() const = 0;
+
+		bool can_read_impl() const override { return false; }
+		bool can_write_impl() const override { SpinLockGuard _(m_spinlock); return m_sample_data_size < m_sample_data_capacity; }
+		bool has_error_impl() const override { return false; }
+		bool has_hungup_impl() const override { return false; }
+
+		BAN::ErrorOr<size_t> write_impl(off_t, BAN::ConstByteSpan) override;
+
+		BAN::ErrorOr<long> ioctl_impl(int cmd, void* arg) override;
+
+	protected:
+		ThreadBlocker m_sample_data_blocker;
+		mutable SpinLock m_spinlock;
+
+		static constexpr size_t m_sample_data_capacity = 1 << 20;
+		uint8_t m_sample_data[m_sample_data_capacity];
+		size_t m_sample_data_head { 0 };
+		size_t m_sample_data_size { 0 };
+
+	private:
+		const dev_t m_rdev;
+		char m_name[10] {};
+	};
+
+}

kernel/include/kernel/Device/DeviceNumbers.h

@@ -22,6 +22,7 @@ namespace Kernel
 		Ethernet,
 		Loopback,
 		TmpFS,
+		AudioController,
 	};
 
 }