Kernel + WindowServer: Re-define the interface to framebuffer devices

We create a base class called GenericFramebufferDevice, which defines
all the virtual functions that must be implemented by a
FramebufferDevice. Then, we make the VirtIO FramebufferDevice and other
FramebufferDevice implementations inherit from it.
The most important consequence of rearranging the classes is that we now
have one IOCTL method, so all drivers should be committed to not
override the IOCTL method or make their own IOCTLs of FramebufferDevice.
All graphical IOCTLs are known to all FramebufferDevices, and it's up to
the specific implementation whether to support them or discard them (so
we require extensive usage of KResult and KResultOr, together with
virtual characteristic functions).
As a result, the interface is much cleaner and understandable to read.

Kernel/Graphics/FramebufferDevice.h

@@ -9,7 +9,7 @@
 #include <AK/NonnullOwnPtr.h>
 #include <AK/String.h>
 #include <AK/Types.h>
-#include <Kernel/Devices/BlockDevice.h>
+#include <Kernel/Graphics/GenericFramebufferDevice.h>
 #include <Kernel/Graphics/GenericGraphicsAdapter.h>
 #include <Kernel/Locking/Spinlock.h>
 #include <Kernel/Memory/AnonymousVMObject.h>
@@ -17,38 +17,38 @@
 
 namespace Kernel {
 
-class FramebufferDevice : public BlockDevice {
+class FramebufferDevice final : public GenericFramebufferDevice {
     AK_MAKE_ETERNAL
     friend class DeviceManagement;
 
 public:
-    static NonnullRefPtr<FramebufferDevice> create(const GenericGraphicsAdapter&, size_t, PhysicalAddress, size_t, size_t, size_t);
+    static NonnullRefPtr<FramebufferDevice> create(const GenericGraphicsAdapter&, PhysicalAddress, size_t, size_t, size_t);
 
-    virtual KResult ioctl(OpenFileDescription&, unsigned request, Userspace<void*> arg) override;
     virtual KResultOr<Memory::Region*> mmap(Process&, OpenFileDescription&, Memory::VirtualRange const&, u64 offset, int prot, bool shared) override;
 
-    virtual void deactivate_writes();
-    virtual void activate_writes();
-    size_t framebuffer_size_in_bytes() const;
+    virtual void deactivate_writes() override;
+    virtual void activate_writes() override;
 
-    virtual ~FramebufferDevice() {};
-    KResult initialize();
+    virtual KResult try_to_initialize() override;
 
-protected:
-    FramebufferDevice(const GenericGraphicsAdapter&, size_t);
-    NonnullRefPtr<GenericGraphicsAdapter> m_graphics_adapter;
+    virtual bool multihead_support() const override { return false; }
+    virtual bool flushing_support() const override { return false; }
+    virtual bool partial_flushing_support() const override { return false; }
+    virtual size_t heads_count() const override { return 1; }
+    virtual KResultOr<size_t> buffer_length(size_t head) const override;
+    virtual KResultOr<size_t> pitch(size_t head) const override;
+    virtual KResultOr<size_t> height(size_t head) const override;
+    virtual KResultOr<size_t> width(size_t head) const override;
+    virtual KResultOr<size_t> vertical_offset(size_t head) const override;
+    virtual KResultOr<bool> vertical_offseted(size_t head) const override;
 
 private:
-    FramebufferDevice(const GenericGraphicsAdapter&, size_t, PhysicalAddress, size_t, size_t, size_t);
+    virtual KResult set_head_resolution(size_t head, size_t width, size_t height, size_t pitch) override;
+    virtual KResult set_head_buffer(size_t head, bool second_buffer) override;
+    virtual KResult flush_head_buffer(size_t head) override;
+    virtual KResult flush_rectangle(size_t head, FBRect const&) override;
 
-    // ^File
-    virtual StringView class_name() const override { return "FramebufferDevice"sv; }
-
-    virtual bool can_read(const OpenFileDescription&, size_t) const override final { return true; }
-    virtual bool can_write(const OpenFileDescription&, size_t) const override final { return true; }
-    virtual void start_request(AsyncBlockDeviceRequest& request) override final { request.complete(AsyncDeviceRequest::Failure); }
-    virtual KResultOr<size_t> read(OpenFileDescription&, u64, UserOrKernelBuffer&, size_t) override { return EINVAL; }
-    virtual KResultOr<size_t> write(OpenFileDescription&, u64, const UserOrKernelBuffer&, size_t) override { return EINVAL; }
+    FramebufferDevice(const GenericGraphicsAdapter&, PhysicalAddress, size_t, size_t, size_t);
 
     PhysicalAddress m_framebuffer_address;
     size_t m_framebuffer_pitch { 0 };
@@ -56,6 +56,7 @@ private:
     size_t m_framebuffer_height { 0 };
 
     Spinlock m_activation_lock;
+    mutable Mutex m_buffer_offset_lock;
 
     RefPtr<Memory::AnonymousVMObject> m_real_framebuffer_vmobject;
     RefPtr<Memory::AnonymousVMObject> m_swapped_framebuffer_vmobject;
@@ -68,7 +69,6 @@ private:
     Memory::Region* m_userspace_framebuffer_region { nullptr };
 
     size_t m_y_offset { 0 };
-    size_t m_output_port_index;
 };
 
 }