Kernel/GPU: Add a simple-framebuffer devicetree driver

simple-framebuffer nodes describe pre-initialized framebuffers that we
can use without any special setup code.

Kernel/CMakeLists.txt

@@ -95,6 +95,7 @@ set(KERNEL_SOURCES
     Devices/GPU/Console/ContiguousFramebufferConsole.cpp
     Devices/GPU/DisplayConnector.cpp
     Devices/GPU/Generic/DisplayConnector.cpp
+    Devices/GPU/Generic/SimpleFramebuffer.cpp
     Devices/GPU/Management.cpp
     Devices/GPU/Intel/Auxiliary/GMBusConnector.cpp
     Devices/GPU/Intel/Plane/DisplayPlane.cpp

Kernel/Devices/GPU/Generic/SimpleFramebuffer.cpp

@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2025, Sönke Holz <sholz8530@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/GenericShorthands.h>
+#include <Kernel/Boot/BootInfo.h>
+#include <Kernel/Devices/GPU/Console/BootFramebufferConsole.h>
+#include <Kernel/Firmware/DeviceTree/DeviceTree.h>
+#include <Kernel/Firmware/DeviceTree/Driver.h>
+#include <Kernel/Firmware/DeviceTree/Management.h>
+
+namespace Kernel {
+extern Atomic<Graphics::Console*> g_boot_console;
+}
+
+namespace Kernel::Graphics {
+
+static constinit Array const compatibles_array = {
+    "simple-framebuffer"sv,
+};
+
+DEVICETREE_DRIVER(SimpleFramebufferDriver, compatibles_array);
+
+// https://www.kernel.org/doc/Documentation/devicetree/bindings/display/simple-framebuffer.yaml
+ErrorOr<void> SimpleFramebufferDriver::probe(DeviceTree::Device const& device, StringView) const
+{
+    // Prefer to use the bootloader-provided framebuffer, if available.
+    if (!g_boot_info.boot_framebuffer.paddr.is_null() && g_boot_info.boot_framebuffer.type == BootFramebufferType::BGRx8888)
+        return {};
+
+    auto maybe_width = device.node().get_property("width"sv);
+    if (!maybe_width.has_value())
+        return EINVAL;
+
+    auto maybe_height = device.node().get_property("height"sv);
+    if (!maybe_height.has_value())
+        return EINVAL;
+
+    auto maybe_stride = device.node().get_property("stride"sv);
+    if (!maybe_stride.has_value())
+        return EINVAL;
+
+    auto maybe_format = device.node().get_property("format"sv);
+    if (!maybe_format.has_value())
+        return EINVAL;
+
+    if (!first_is_one_of(maybe_format.value().as_string(), "a8r8g8b8"sv, "x8r8g8b8"sv))
+        return ENOTSUP;
+
+    auto framebuffer_resource = TRY(device.get_resource(0));
+
+    g_boot_info.boot_framebuffer = {
+        .paddr = framebuffer_resource.paddr,
+        .pitch = maybe_stride.release_value().as<u32>(),
+        .width = maybe_width.release_value().as<u32>(),
+        .height = maybe_height.release_value().as<u32>(),
+        .bpp = 32,
+        .type = BootFramebufferType::BGRx8888,
+    };
+
+    // Devicetree drivers are probed after the initial boot console is set up, so we need to re-initialize the g_boot_console to use the this framebuffer.
+    // g_boot_console should currently be a BootDummyConsole, as we ignore the simple-framebuffer node if the bootloader provided a framebuffer.
+    auto boot_console = TRY(try_make_lock_ref_counted<Graphics::BootFramebufferConsole>(g_boot_info.boot_framebuffer.paddr, g_boot_info.boot_framebuffer.width, g_boot_info.boot_framebuffer.height, g_boot_info.boot_framebuffer.pitch));
+    auto* old_boot_console = g_boot_console.exchange(&boot_console.leak_ref());
+    if (old_boot_console != nullptr)
+        old_boot_console->unref();
+
+    return {};
+}
+
+}