From 56d50ea2e8651020f3c02e4a153118aed11ac37f Mon Sep 17 00:00:00 2001
From: Rafal Kupiec <belliash@codingworkshop.eu.org>
Date: Thu, 21 Mar 2024 15:40:09 +0100
Subject: [PATCH] Implement EDID support for getting the preferred screen
 resolution

---
 sdk/xtdk/bltypes.h                         |  2 +
 xtldr/modules/framebuf/framebuf.c          | 58 ++++++++++++++++++++++
 xtldr/modules/framebuf/includes/framebuf.h |  5 ++
 3 files changed, 65 insertions(+)

diff --git a/sdk/xtdk/bltypes.h b/sdk/xtdk/bltypes.h
index 063ba79..86a767f 100644
--- a/sdk/xtdk/bltypes.h
+++ b/sdk/xtdk/bltypes.h
@@ -129,6 +129,7 @@ typedef EFI_STATUS (*PBL_EXECIMAGE_UNLOAD_IMAGE)(IN PVOID ImagePointer);
 typedef EFI_STATUS (*PBL_EXECIMAGE_VERIFY_IMAGE)(IN PVOID ImagePointer);
 typedef EFI_STATUS (*PBL_FRAMEBUFFER_GET_DISPLAY_DRIVER)(OUT PEFI_GRAPHICS_PROTOCOL Protocol);
 typedef EFI_STATUS (*PBL_FRAMEBUFFER_GET_DISPLAY_INFORMATION)(OUT PEFI_PHYSICAL_ADDRESS FrameBufferBase, OUT PULONG_PTR FrameBufferSize, OUT PXTBL_FRAMEBUFFER_MODE_INFORMATION ModeInfo);
+typedef EFI_STATUS (*PBL_FRAMEBUFFER_GET_PREFERRED_SCREEN_RESOLUTION)(OUT PUINT PreferredWidth, OUT PUINT PreferredHeight);
 typedef EFI_STATUS (*PBL_FRAMEBUFFER_INITIALIZE)();
 typedef EFI_STATUS (*PBL_FRAMEBUFFER_SET_SCREEN_RESOLUTION)(IN UINT Width, IN UINT Height);
 
@@ -334,6 +335,7 @@ typedef struct _XTBL_FRAMEBUFFER_PROTOCOL
 {
     PBL_FRAMEBUFFER_GET_DISPLAY_DRIVER GetDisplayDriver;
     PBL_FRAMEBUFFER_GET_DISPLAY_INFORMATION GetDisplayInformation;
+    PBL_FRAMEBUFFER_GET_PREFERRED_SCREEN_RESOLUTION GetPreferredScreenResolution;
     PBL_FRAMEBUFFER_INITIALIZE Initialize;
     PBL_FRAMEBUFFER_SET_SCREEN_RESOLUTION SetScreenResolution;
 } XTBL_FRAMEBUFFER_PROTOCOL, *PXTBL_FRAMEBUFFER_PROTOCOL;
diff --git a/xtldr/modules/framebuf/framebuf.c b/xtldr/modules/framebuf/framebuf.c
index fda20b4..250e1c1 100644
--- a/xtldr/modules/framebuf/framebuf.c
+++ b/xtldr/modules/framebuf/framebuf.c
@@ -86,6 +86,63 @@ FbGetDisplayInformation(OUT PEFI_PHYSICAL_ADDRESS FrameBufferBase,
     return STATUS_EFI_SUCCESS;
 }
 
+/**
+ * Determines the preferred (native) screen resolution from EDID. This works only with GOP.
+ *
+ * @param PreferredWidth
+ *        Supplies a pointer to the memory area where preferred screen width will be stored.
+ *
+ * @param PreferredHeight
+ *        Supplies a pointer to the memory area where preferred screen height will be stored.
+ *
+ * @return This routine returns a status code.
+ *
+ * @since XT 1.0
+ */
+XTCDECL
+EFI_STATUS
+FbGetPreferredScreenResolution(OUT PUINT PreferredWidth,
+                               OUT PUINT PreferredHeight)
+{
+    EFI_GUID GopGuid = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
+    EFI_GUID EdidGuid = EFI_EDID_ACTIVE_PROTOCOL_GUID;
+    PEFI_EDID_ACTIVE_PROTOCOL ActiveEdid;
+    EFI_STATUS Status;
+
+    /* Check if framebuffer is initialized */
+    if(!FbpDisplayInfo.Initialized)
+    {
+        /* Framebuffer not ready to use EDID protocol */
+        return STATUS_EFI_NOT_READY;
+    }
+
+    /* Check if GOP device driver is used */
+    if(FbpDisplayInfo.Protocol != GOP)
+    {
+        /* Unsupported device driver */
+        return STATUS_EFI_UNSUPPORTED;
+    }
+
+    /* Open EDID protocol */
+    Status = XtLdrProtocol->Protocol.OpenHandle(FbpDisplayInfo.Handle, (PVOID *)&ActiveEdid, &EdidGuid);
+    if(Status != STATUS_EFI_SUCCESS)
+    {
+        /* Failed to open EDID protocol, close GOP protocol and return */
+        XtLdrProtocol->Protocol.Close(FbpDisplayInfo.Handle, &GopGuid);
+        return Status;
+    }
+
+    /* Return preferred screen resolution */
+    *PreferredWidth = ActiveEdid->Edid[0x38] | ((ActiveEdid->Edid[0x3A] & 0xF0) << 4);
+    *PreferredHeight = ActiveEdid->Edid[0x3B] | ((ActiveEdid->Edid[0x3D] & 0xF0) << 4);
+
+    /* Close EDID & GOP protocols */
+    XtLdrProtocol->Protocol.Close(FbpDisplayInfo.Handle, &EdidGuid);
+
+    /* Return success */
+    return STATUS_EFI_SUCCESS;
+}
+
 /**
  * Initializes FrameBuffer device on GOP and UGA compatible adapters.
  *
@@ -717,6 +774,7 @@ XtLdrModuleMain(IN EFI_HANDLE ImageHandle,
     /* Set routines available via XTLDR framebuffer protocol */
     FbpFrameBufferProtocol.GetDisplayDriver = FbGetDisplayDriver;
     FbpFrameBufferProtocol.GetDisplayInformation = FbGetDisplayInformation;
+    FbpFrameBufferProtocol.GetPreferredScreenResolution = FbGetPreferredScreenResolution;
     FbpFrameBufferProtocol.Initialize = FbInitializeDisplay;
     FbpFrameBufferProtocol.SetScreenResolution = FbSetScreenResolution;
 
diff --git a/xtldr/modules/framebuf/includes/framebuf.h b/xtldr/modules/framebuf/includes/framebuf.h
index f93605c..85bad6c 100644
--- a/xtldr/modules/framebuf/includes/framebuf.h
+++ b/xtldr/modules/framebuf/includes/framebuf.h
@@ -24,6 +24,11 @@ FbGetDisplayInformation(OUT PEFI_PHYSICAL_ADDRESS FrameBufferBase,
                         OUT PULONG_PTR FrameBufferSize,
                         OUT PXTBL_FRAMEBUFFER_MODE_INFORMATION ModeInfo);
 
+XTCDECL
+EFI_STATUS
+FbGetPreferredScreenResolution(OUT PUINT PreferredWidth,
+                               OUT PUINT PreferredHeight);
+
 XTCDECL
 EFI_STATUS
 FbInitializeDisplay();