Kernel: Move SCSI device rdev allocation out of ATA code

kernel/CMakeLists.txt

@@ -89,6 +89,7 @@ set(KERNEL_SOURCES
 	kernel/Storage/NVMe/Namespace.cpp
 	kernel/Storage/NVMe/Queue.cpp
 	kernel/Storage/Partition.cpp
+	kernel/Storage/SCSI.cpp
 	kernel/Storage/StorageDevice.cpp
 	kernel/Syscall.cpp
 	kernel/Terminal/FramebufferTerminal.cpp

kernel/include/kernel/Storage/ATA/ATADevice.h

@@ -19,7 +19,7 @@ namespace Kernel
 			};
 
 		public:
-			virtual ~ATABaseDevice() {};
+			virtual ~ATABaseDevice();
 
 			virtual uint32_t sector_size() const override { return m_sector_words * 2; }
 			virtual uint64_t total_size() const override { return m_lba_count * sector_size(); }

kernel/include/kernel/Storage/SCSI.h

@@ -0,0 +1,11 @@
+#pragma once
+
+#include <sys/types.h>
+
+namespace Kernel
+{
+
+	dev_t scsi_get_rdev();
+	void scsi_free_rdev(dev_t);
+
+}

kernel/kernel/Storage/ATA/ATADevice.cpp

@@ -4,25 +4,25 @@
 #include <kernel/Storage/ATA/ATABus.h>
 #include <kernel/Storage/ATA/ATADefinitions.h>
 #include <kernel/Storage/ATA/ATADevice.h>
+#include <kernel/Storage/SCSI.h>
 
 #include <sys/sysmacros.h>
 
 namespace Kernel
 {
 
-	static dev_t get_ata_dev_minor()
-	{
-		static dev_t minor = 0;
-		return minor++;
-	}
-
 	detail::ATABaseDevice::ATABaseDevice()
-		: m_rdev(makedev(DeviceNumber::SCSI, get_ata_dev_minor()))
+		: m_rdev(scsi_get_rdev())
 	{
 		strcpy(m_name, "sda");
 		m_name[2] += minor(m_rdev);
 	}
 
+	detail::ATABaseDevice::~ATABaseDevice()
+	{
+		scsi_free_rdev(m_rdev);
+	}
+
 	BAN::ErrorOr<void> detail::ATABaseDevice::initialize(BAN::Span<const uint16_t> identify_data)
 	{
 		ASSERT(identify_data.size() >= 256);

kernel/kernel/Storage/SCSI.cpp

@@ -0,0 +1,44 @@
+#include <kernel/Device/DeviceNumbers.h>
+#include <kernel/Lock/SpinLock.h>
+#include <kernel/Storage/SCSI.h>
+
+#include <sys/sysmacros.h>
+
+namespace Kernel
+{
+
+	static uint64_t s_scsi_bitmap { 0 };
+	static SpinLock s_scsi_spinlock;
+
+	static constexpr size_t s_scsi_bitmap_bits = sizeof(s_scsi_bitmap) * 8;
+
+	dev_t scsi_get_rdev()
+	{
+		SpinLockGuard _(s_scsi_spinlock);
+
+		uint64_t mask = 1;
+		for (uint8_t minor = 0; minor < s_scsi_bitmap_bits; minor++, mask <<= 1)
+		{
+			if (s_scsi_bitmap & mask)
+				continue;
+			s_scsi_bitmap |= mask;
+
+			return makedev(DeviceNumber::SCSI, minor);
+		}
+
+		ASSERT_NOT_REACHED();
+	}
+
+	void scsi_free_rdev(dev_t rdev)
+	{
+		ASSERT(major(rdev) == static_cast<dev_t>(DeviceNumber::SCSI));
+
+		SpinLockGuard _(s_scsi_spinlock);
+
+		const uint64_t mask = static_cast<uint64_t>(1) << minor(rdev);
+		ASSERT(s_scsi_bitmap & mask);
+
+		s_scsi_bitmap &= ~mask;
+	}
+
+}