Kernel/Graphics: Introduce a new mechanism to initialize a PCI device

Instead of using a clunky switch-case paradigm, we now have all drivers
being declaring two methods for their adapter class - create and probe.
These methods are linked in each PCIGraphicsDriverInitializer structure,
in a new s_initializers static list of them.
Then, when we probe for a PCI device, we use each probe method and if
there's a match, then the corresponding create method is called.

As a result of this change, it's much more easy to add more drivers and
the initialization code is more readable.

12 files changed, 85 insertions, 71 deletions

diff --git a/Kernel/Graphics/Bochs/GraphicsAdapter.cpp b/Kernel/Graphics/Bochs/GraphicsAdapter.cpp
index 09a23f42f4..2494c6f448 100644
--- a/Kernel/Graphics/Bochs/GraphicsAdapter.cpp
+++ b/Kernel/Graphics/Bochs/GraphicsAdapter.cpp
@@ -22,17 +22,25 @@
 
 namespace Kernel {
 
-UNMAP_AFTER_INIT NonnullLockRefPtr<BochsGraphicsAdapter> BochsGraphicsAdapter::initialize(PCI::DeviceIdentifier const& pci_device_identifier)
+UNMAP_AFTER_INIT ErrorOr<bool> BochsGraphicsAdapter::probe(PCI::DeviceIdentifier const& pci_device_identifier)
 {
     PCI::HardwareID id = pci_device_identifier.hardware_id();
-    VERIFY((id.vendor_id == PCI::VendorID::QEMUOld && id.device_id == 0x1111) || (id.vendor_id == PCI::VendorID::VirtualBox && id.device_id == 0xbeef));
-    auto adapter = adopt_lock_ref(*new BochsGraphicsAdapter(pci_device_identifier));
+    if (id.vendor_id == PCI::VendorID::QEMUOld && id.device_id == 0x1111)
+        return true;
+    if (id.vendor_id == PCI::VendorID::VirtualBox && id.device_id == 0xbeef)
+        return true;
+    return false;
+}
+
+UNMAP_AFTER_INIT ErrorOr<NonnullLockRefPtr<GenericGraphicsAdapter>> BochsGraphicsAdapter::create(PCI::DeviceIdentifier const& pci_device_identifier)
+{
+    auto adapter = TRY(adopt_nonnull_lock_ref_or_enomem(new (nothrow) BochsGraphicsAdapter(pci_device_identifier.address())));
     MUST(adapter->initialize_adapter(pci_device_identifier));
     return adapter;
 }
 
-UNMAP_AFTER_INIT BochsGraphicsAdapter::BochsGraphicsAdapter(PCI::DeviceIdentifier const& pci_device_identifier)
-    : PCI::Device(pci_device_identifier.address())
+UNMAP_AFTER_INIT BochsGraphicsAdapter::BochsGraphicsAdapter(PCI::Address const& address)
+    : PCI::Device(address)
 {
 }
 
diff --git a/Kernel/Graphics/Bochs/GraphicsAdapter.h b/Kernel/Graphics/Bochs/GraphicsAdapter.h
index 5fca7601a1..b865c40553 100644
--- a/Kernel/Graphics/Bochs/GraphicsAdapter.h
+++ b/Kernel/Graphics/Bochs/GraphicsAdapter.h
@@ -24,14 +24,15 @@ class BochsGraphicsAdapter final : public GenericGraphicsAdapter
     friend class GraphicsManagement;
 
 public:
-    static NonnullLockRefPtr<BochsGraphicsAdapter> initialize(PCI::DeviceIdentifier const&);
+    static ErrorOr<bool> probe(PCI::DeviceIdentifier const&);
+    static ErrorOr<NonnullLockRefPtr<GenericGraphicsAdapter>> create(PCI::DeviceIdentifier const&);
     virtual ~BochsGraphicsAdapter() = default;
     virtual StringView device_name() const override { return "BochsGraphicsAdapter"sv; }
 
 private:
     ErrorOr<void> initialize_adapter(PCI::DeviceIdentifier const&);
 
-    explicit BochsGraphicsAdapter(PCI::DeviceIdentifier const&);
+    explicit BochsGraphicsAdapter(PCI::Address const&);
 
     LockRefPtr<DisplayConnector> m_display_connector;
 };
diff --git a/Kernel/Graphics/GraphicsManagement.cpp b/Kernel/Graphics/GraphicsManagement.cpp
index a65e69d58f..3fc595d4e2 100644
--- a/Kernel/Graphics/GraphicsManagement.cpp
+++ b/Kernel/Graphics/GraphicsManagement.cpp
@@ -120,40 +120,35 @@ static inline bool is_display_controller_pci_device(PCI::DeviceIdentifier const&
     return device_identifier.class_code().value() == 0x3;
 }
 
-UNMAP_AFTER_INIT bool GraphicsManagement::determine_and_initialize_graphics_device(PCI::DeviceIdentifier const& device_identifier)
+struct PCIGraphicsDriverInitializer {
+    ErrorOr<bool> (*probe)(PCI::DeviceIdentifier const&) = nullptr;
+    ErrorOr<NonnullLockRefPtr<GenericGraphicsAdapter>> (*create)(PCI::DeviceIdentifier const&) = nullptr;
+};
+
+static constexpr PCIGraphicsDriverInitializer s_initializers[] = {
+    { IntelNativeGraphicsAdapter::probe, IntelNativeGraphicsAdapter::create },
+    { BochsGraphicsAdapter::probe, BochsGraphicsAdapter::create },
+    { VirtIOGraphicsAdapter::probe, VirtIOGraphicsAdapter::create },
+    { VMWareGraphicsAdapter::probe, VMWareGraphicsAdapter::create },
+};
+
+UNMAP_AFTER_INIT ErrorOr<void> GraphicsManagement::determine_and_initialize_graphics_device(PCI::DeviceIdentifier const& device_identifier)
 {
     VERIFY(is_vga_compatible_pci_device(device_identifier) || is_display_controller_pci_device(device_identifier));
-    LockRefPtr<GenericGraphicsAdapter> adapter;
-
-    if (!adapter) {
-        switch (device_identifier.hardware_id().vendor_id) {
-        case PCI::VendorID::QEMUOld:
-            if (device_identifier.hardware_id().device_id == 0x1111)
-                adapter = BochsGraphicsAdapter::initialize(device_identifier);
-            break;
-        case PCI::VendorID::VirtualBox:
-            if (device_identifier.hardware_id().device_id == 0xbeef)
-                adapter = BochsGraphicsAdapter::initialize(device_identifier);
-            break;
-        case PCI::VendorID::Intel:
-            adapter = IntelNativeGraphicsAdapter::initialize(device_identifier);
-            break;
-        case PCI::VendorID::VirtIO:
-            dmesgln("Graphics: Using VirtIO console");
-            adapter = VirtIOGraphicsAdapter::initialize(device_identifier);
-            break;
-        case PCI::VendorID::VMWare:
-            adapter = VMWareGraphicsAdapter::try_initialize(device_identifier);
-            break;
-        default:
-            break;
+    for (auto& initializer : s_initializers) {
+        auto initializer_probe_found_driver_match_or_error = initializer.probe(device_identifier);
+        if (initializer_probe_found_driver_match_or_error.is_error()) {
+            dmesgln("Graphics: Failed to probe device {}, due to {}", device_identifier.address(), initializer_probe_found_driver_match_or_error.error());
+            continue;
+        }
+        auto initializer_probe_found_driver_match = initializer_probe_found_driver_match_or_error.release_value();
+        if (initializer_probe_found_driver_match) {
+            auto adapter = TRY(initializer.create(device_identifier));
+            TRY(m_graphics_devices.try_append(*adapter));
+            return {};
         }
     }
-
-    if (!adapter)
-        return false;
-    m_graphics_devices.append(*adapter);
-    return true;
+    return {};
 }
 
 UNMAP_AFTER_INIT void GraphicsManagement::initialize_preset_resolution_generic_display_connector()
@@ -239,7 +234,8 @@ UNMAP_AFTER_INIT bool GraphicsManagement::initialize()
         // framebuffer console will take the control instead.
         if (!is_vga_compatible_pci_device(device_identifier) && !is_display_controller_pci_device(device_identifier))
             return;
-        determine_and_initialize_graphics_device(device_identifier);
+        if (auto result = determine_and_initialize_graphics_device(device_identifier); result.is_error())
+            dbgln("Failed to initialize device {}, due to {}", device_identifier.address(), result.error());
     }));
 
     // Note: If we failed to find any graphics device to be used natively, but the
diff --git a/Kernel/Graphics/GraphicsManagement.h b/Kernel/Graphics/GraphicsManagement.h
index ec771c6528..ee30adf3ce 100644
--- a/Kernel/Graphics/GraphicsManagement.h
+++ b/Kernel/Graphics/GraphicsManagement.h
@@ -50,7 +50,7 @@ public:
 private:
     void enable_vga_text_mode_console_cursor();
 
-    bool determine_and_initialize_graphics_device(PCI::DeviceIdentifier const&);
+    ErrorOr<void> determine_and_initialize_graphics_device(PCI::DeviceIdentifier const&);
 
     void initialize_preset_resolution_generic_display_connector();
 
diff --git a/Kernel/Graphics/Intel/NativeDisplayConnector.cpp b/Kernel/Graphics/Intel/NativeDisplayConnector.cpp
index 4ce94adf0c..260839d436 100644
--- a/Kernel/Graphics/Intel/NativeDisplayConnector.cpp
+++ b/Kernel/Graphics/Intel/NativeDisplayConnector.cpp
@@ -175,20 +175,18 @@ Optional<IntelGraphics::PLLSettings> IntelNativeDisplayConnector::create_pll_set
     return {};
 }
 
-NonnullLockRefPtr<IntelNativeDisplayConnector> IntelNativeDisplayConnector::must_create(PhysicalAddress framebuffer_address, size_t framebuffer_resource_size, PhysicalAddress registers_region_address, size_t registers_region_length)
+ErrorOr<NonnullLockRefPtr<IntelNativeDisplayConnector>> IntelNativeDisplayConnector::try_create(PhysicalAddress framebuffer_address, size_t framebuffer_resource_size, PhysicalAddress registers_region_address, size_t registers_region_length)
 {
-    auto registers_region = MUST(MM.allocate_kernel_region(PhysicalAddress(registers_region_address), registers_region_length, "Intel Native Graphics Registers"sv, Memory::Region::Access::ReadWrite));
-    auto device_or_error = DeviceManagement::try_create_device<IntelNativeDisplayConnector>(framebuffer_address, framebuffer_resource_size, move(registers_region));
-    VERIFY(!device_or_error.is_error());
-    auto connector = device_or_error.release_value();
-    MUST(connector->initialize_gmbus_settings_and_read_edid());
+    auto registers_region = TRY(MM.allocate_kernel_region(PhysicalAddress(registers_region_address), registers_region_length, "Intel Native Graphics Registers"sv, Memory::Region::Access::ReadWrite));
+    auto connector = TRY(DeviceManagement::try_create_device<IntelNativeDisplayConnector>(framebuffer_address, framebuffer_resource_size, move(registers_region)));
+    TRY(connector->initialize_gmbus_settings_and_read_edid());
     // Note: This is very important to set the resolution to something safe so we
     // can create a framebuffer console with valid resolution.
     {
         SpinlockLocker control_lock(connector->m_control_lock);
-        MUST(connector->set_safe_mode_setting());
+        TRY(connector->set_safe_mode_setting());
     }
-    MUST(connector->create_attached_framebuffer_console());
+    TRY(connector->create_attached_framebuffer_console());
     return connector;
 }
 
diff --git a/Kernel/Graphics/Intel/NativeDisplayConnector.h b/Kernel/Graphics/Intel/NativeDisplayConnector.h
index 0cd60a4358..d8649d08f6 100644
--- a/Kernel/Graphics/Intel/NativeDisplayConnector.h
+++ b/Kernel/Graphics/Intel/NativeDisplayConnector.h
@@ -81,7 +81,7 @@ class IntelNativeDisplayConnector final
     friend class DeviceManagement;
 
 public:
-    static NonnullLockRefPtr<IntelNativeDisplayConnector> must_create(PhysicalAddress framebuffer_address, size_t framebuffer_resource_size, PhysicalAddress registers_region_address, size_t registers_region_length);
+    static ErrorOr<NonnullLockRefPtr<IntelNativeDisplayConnector>> try_create(PhysicalAddress framebuffer_address, size_t framebuffer_resource_size, PhysicalAddress registers_region_address, size_t registers_region_length);
 
 private:
     // ^DisplayConnector
diff --git a/Kernel/Graphics/Intel/NativeGraphicsAdapter.cpp b/Kernel/Graphics/Intel/NativeGraphicsAdapter.cpp
index f410fceb75..6e583a0d58 100644
--- a/Kernel/Graphics/Intel/NativeGraphicsAdapter.cpp
+++ b/Kernel/Graphics/Intel/NativeGraphicsAdapter.cpp
@@ -26,13 +26,15 @@ static bool is_supported_model(u16 device_id)
     return false;
 }
 
-LockRefPtr<IntelNativeGraphicsAdapter> IntelNativeGraphicsAdapter::initialize(PCI::DeviceIdentifier const& pci_device_identifier)
+ErrorOr<bool> IntelNativeGraphicsAdapter::probe(PCI::DeviceIdentifier const& pci_device_identifier)
 {
-    VERIFY(pci_device_identifier.hardware_id().vendor_id == 0x8086);
-    if (!is_supported_model(pci_device_identifier.hardware_id().device_id))
-        return {};
-    auto adapter = adopt_lock_ref(*new IntelNativeGraphicsAdapter(pci_device_identifier.address()));
-    MUST(adapter->initialize_adapter());
+    return is_supported_model(pci_device_identifier.hardware_id().device_id);
+}
+
+ErrorOr<NonnullLockRefPtr<GenericGraphicsAdapter>> IntelNativeGraphicsAdapter::create(PCI::DeviceIdentifier const& pci_device_identifier)
+{
+    auto adapter = TRY(adopt_nonnull_lock_ref_or_enomem(new (nothrow) IntelNativeGraphicsAdapter(pci_device_identifier.address())));
+    TRY(adapter->initialize_adapter());
     return adapter;
 }
 
@@ -47,7 +49,7 @@ ErrorOr<void> IntelNativeGraphicsAdapter::initialize_adapter()
     dmesgln_pci(*this, "framebuffer @ {}", PhysicalAddress(PCI::get_BAR2(address)));
     PCI::enable_bus_mastering(address);
 
-    m_display_connector = IntelNativeDisplayConnector::must_create(PhysicalAddress(PCI::get_BAR2(address) & 0xfffffff0), bar2_space_size, PhysicalAddress(PCI::get_BAR0(address) & 0xfffffff0), bar0_space_size);
+    m_display_connector = TRY(IntelNativeDisplayConnector::try_create(PhysicalAddress(PCI::get_BAR2(address) & 0xfffffff0), bar2_space_size, PhysicalAddress(PCI::get_BAR0(address) & 0xfffffff0), bar0_space_size));
     return {};
 }
 
diff --git a/Kernel/Graphics/Intel/NativeGraphicsAdapter.h b/Kernel/Graphics/Intel/NativeGraphicsAdapter.h
index b7c58dea8a..3cdb170bbc 100644
--- a/Kernel/Graphics/Intel/NativeGraphicsAdapter.h
+++ b/Kernel/Graphics/Intel/NativeGraphicsAdapter.h
@@ -20,7 +20,8 @@ class IntelNativeGraphicsAdapter final
     , public PCI::Device {
 
 public:
-    static LockRefPtr<IntelNativeGraphicsAdapter> initialize(PCI::DeviceIdentifier const&);
+    static ErrorOr<bool> probe(PCI::DeviceIdentifier const&);
+    static ErrorOr<NonnullLockRefPtr<GenericGraphicsAdapter>> create(PCI::DeviceIdentifier const&);
 
     virtual ~IntelNativeGraphicsAdapter() = default;
 
diff --git a/Kernel/Graphics/VMWare/GraphicsAdapter.cpp b/Kernel/Graphics/VMWare/GraphicsAdapter.cpp
index 839fe23df5..43f00f3222 100644
--- a/Kernel/Graphics/VMWare/GraphicsAdapter.cpp
+++ b/Kernel/Graphics/VMWare/GraphicsAdapter.cpp
@@ -20,16 +20,18 @@
 
 namespace Kernel {
 
-UNMAP_AFTER_INIT LockRefPtr<VMWareGraphicsAdapter> VMWareGraphicsAdapter::try_initialize(PCI::DeviceIdentifier const& pci_device_identifier)
+ErrorOr<bool> VMWareGraphicsAdapter::probe(PCI::DeviceIdentifier const& pci_device_identifier)
 {
     PCI::HardwareID id = pci_device_identifier.hardware_id();
-    VERIFY(id.vendor_id == PCI::VendorID::VMWare);
     // Note: We only support VMWare SVGA II adapter
-    if (id.device_id != 0x0405)
-        return {};
-    auto registers_io_window = MUST(IOWindow::create_for_pci_device_bar(pci_device_identifier, PCI::HeaderType0BaseRegister::BAR0));
-    auto adapter = MUST(adopt_nonnull_lock_ref_or_enomem(new (nothrow) VMWareGraphicsAdapter(pci_device_identifier, move(registers_io_window))));
-    MUST(adapter->initialize_adapter());
+    return id.vendor_id == PCI::VendorID::VMWare && id.device_id == 0x0405;
+}
+
+ErrorOr<NonnullLockRefPtr<GenericGraphicsAdapter>> VMWareGraphicsAdapter::create(PCI::DeviceIdentifier const& pci_device_identifier)
+{
+    auto registers_io_window = TRY(IOWindow::create_for_pci_device_bar(pci_device_identifier, PCI::HeaderType0BaseRegister::BAR0));
+    auto adapter = TRY(adopt_nonnull_lock_ref_or_enomem(new (nothrow) VMWareGraphicsAdapter(pci_device_identifier, move(registers_io_window))));
+    TRY(adapter->initialize_adapter());
     return adapter;
 }
 
diff --git a/Kernel/Graphics/VMWare/GraphicsAdapter.h b/Kernel/Graphics/VMWare/GraphicsAdapter.h
index fd159fb9fa..06c35efaa5 100644
--- a/Kernel/Graphics/VMWare/GraphicsAdapter.h
+++ b/Kernel/Graphics/VMWare/GraphicsAdapter.h
@@ -26,7 +26,8 @@ class VMWareGraphicsAdapter final
     friend class GraphicsManagement;
 
 public:
-    static LockRefPtr<VMWareGraphicsAdapter> try_initialize(PCI::DeviceIdentifier const&);
+    static ErrorOr<bool> probe(PCI::DeviceIdentifier const&);
+    static ErrorOr<NonnullLockRefPtr<GenericGraphicsAdapter>> create(PCI::DeviceIdentifier const&);
     virtual ~VMWareGraphicsAdapter() = default;
 
     virtual StringView device_name() const override { return "VMWareGraphicsAdapter"sv; }
diff --git a/Kernel/Graphics/VirtIOGPU/GraphicsAdapter.cpp b/Kernel/Graphics/VirtIOGPU/GraphicsAdapter.cpp
index 5e8872011f..040db751d8 100644
--- a/Kernel/Graphics/VirtIOGPU/GraphicsAdapter.cpp
+++ b/Kernel/Graphics/VirtIOGPU/GraphicsAdapter.cpp
@@ -22,19 +22,23 @@ namespace Kernel {
 #define DEVICE_EVENTS_CLEAR 0x4
 #define DEVICE_NUM_SCANOUTS 0x8
 
-NonnullLockRefPtr<VirtIOGraphicsAdapter> VirtIOGraphicsAdapter::initialize(PCI::DeviceIdentifier const& device_identifier)
+ErrorOr<bool> VirtIOGraphicsAdapter::probe(PCI::DeviceIdentifier const& device_identifier)
+{
+    return device_identifier.hardware_id().vendor_id == PCI::VendorID::VirtIO;
+}
+
+ErrorOr<NonnullLockRefPtr<GenericGraphicsAdapter>> VirtIOGraphicsAdapter::create(PCI::DeviceIdentifier const& device_identifier)
 {
-    VERIFY(device_identifier.hardware_id().vendor_id == PCI::VendorID::VirtIO);
     // Setup memory transfer region
-    auto scratch_space_region = MUST(MM.allocate_contiguous_kernel_region(
+    auto scratch_space_region = TRY(MM.allocate_contiguous_kernel_region(
         32 * PAGE_SIZE,
         "VirtGPU Scratch Space"sv,
         Memory::Region::Access::ReadWrite));
 
-    auto active_context_ids = MUST(Bitmap::create(VREND_MAX_CTX, false));
-    auto adapter = adopt_lock_ref(*new (nothrow) VirtIOGraphicsAdapter(device_identifier, move(active_context_ids), move(scratch_space_region)));
+    auto active_context_ids = TRY(Bitmap::create(VREND_MAX_CTX, false));
+    auto adapter = TRY(adopt_nonnull_lock_ref_or_enomem(new (nothrow) VirtIOGraphicsAdapter(device_identifier, move(active_context_ids), move(scratch_space_region))));
     adapter->initialize();
-    MUST(adapter->initialize_adapter());
+    TRY(adapter->initialize_adapter());
     return adapter;
 }
 
diff --git a/Kernel/Graphics/VirtIOGPU/GraphicsAdapter.h b/Kernel/Graphics/VirtIOGPU/GraphicsAdapter.h
index bc6bf22b5e..ec01de1e76 100644
--- a/Kernel/Graphics/VirtIOGPU/GraphicsAdapter.h
+++ b/Kernel/Graphics/VirtIOGPU/GraphicsAdapter.h
@@ -37,7 +37,8 @@ class VirtIOGraphicsAdapter final
     friend class VirtIOGPU3DDevice;
 
 public:
-    static NonnullLockRefPtr<VirtIOGraphicsAdapter> initialize(PCI::DeviceIdentifier const&);
+    static ErrorOr<bool> probe(PCI::DeviceIdentifier const&);
+    static ErrorOr<NonnullLockRefPtr<GenericGraphicsAdapter>> create(PCI::DeviceIdentifier const&);
 
     virtual void initialize() override;