From bb9522350163b30749d0bdac0f70a9ec7a05545a Mon Sep 17 00:00:00 2001
From: belliash <belliash@codingworkshop.eu.org>
Date: Tue, 3 Jan 2023 00:10:24 +0100
Subject: [PATCH] Implement BlActivateSerialControllerIO() routine for
 activating I/O space access on PCI(E) serial controllers

---
 xtldr/efiutil.c       | 117 ++++++++++++++++++++++++++++++++++++++++++
 xtldr/includes/xtbl.h |   4 ++
 2 files changed, 121 insertions(+)

diff --git a/xtldr/efiutil.c b/xtldr/efiutil.c
index 243fc27..562f4b4 100644
--- a/xtldr/efiutil.c
+++ b/xtldr/efiutil.c
@@ -9,6 +9,108 @@
 #include <xtbl.h>
 
 
+/**
+ * Enables I/O space access to all serial controllers found on the PCI(E) root bridge.
+ *
+ * @return This routine returns a status code.
+ *
+ * @since XT 1.0
+ */
+XTCDECL
+EFI_STATUS
+BlActivateSerialControllerIO()
+{
+    EFI_GUID PciGuid = EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL_GUID;
+    PEFI_PCI_ROOT_BRIDGE_IO_PROTOCOL PciDev;
+    USHORT Bus, Device, Function, Command;
+    UINT_PTR Index, PciHandleSize;
+    PEFI_HANDLE PciHandle = NULL;
+    PCI_COMMON_HEADER PciHeader;
+    EFI_STATUS Status;
+    UINT64 Address;
+
+    /* Allocate memory for single EFI_HANDLE, what should be enough in most cases */
+    PciHandleSize = sizeof(EFI_HANDLE);
+    Status = BlEfiMemoryAllocatePool(PciHandleSize, (PVOID*)&PciHandle);
+    if(Status != STATUS_EFI_SUCCESS)
+    {
+        /* Memory allocation failure */
+        return Status;
+    }
+
+    /* Get all instances of PciRootBridgeIo */
+    Status = EfiSystemTable->BootServices->LocateHandle(ByProtocol, &PciGuid, NULL, &PciHandleSize, PciHandle);
+    if(Status == STATUS_EFI_BUFFER_TOO_SMALL)
+    {
+        /* Reallocate more memory as requested by UEFI */
+        BlEfiMemoryFreePool(PciHandle);
+        Status = BlEfiMemoryAllocatePool(PciHandleSize, (PVOID*)&PciHandle);
+        if(Status != STATUS_EFI_SUCCESS)
+        {
+            /* Memory reallocation failure */
+            return Status;
+        }
+
+        /* Second attempt to get instances of PciRootBridgeIo */
+        Status = EfiSystemTable->BootServices->LocateHandle(ByProtocol, &PciGuid, NULL, &PciHandleSize, PciHandle);
+    }
+
+    /* Make sure successfully obtained PciRootBridgeIo instances */
+    if(Status != STATUS_EFI_SUCCESS)
+    {
+        /* Failed to get PciRootBridgeIo instances */
+        return Status;
+    }
+
+    /* Enumerate all devices for each handle, which decides a segment and a bus number range */
+    for(Index = 0; Index < (PciHandleSize / sizeof(EFI_HANDLE)); Index++)
+    {
+        /* Get inferface from the protocol */
+        Status = EfiSystemTable->BootServices->HandleProtocol(PciHandle[Index], &PciGuid, (PVOID*)&PciDev);
+        if(Status != STATUS_EFI_SUCCESS)
+        {
+            /* Failed to get interface */
+            return Status;
+        }
+
+        /* Enumerate whole PCI bridge */
+        for(Bus = 0; Bus <= PCI_MAX_BRIDGE_NUMBER; Bus++)
+        {
+            /* Enumerate all devices for each bus */
+            for(Device = 0; Device < PCI_MAX_DEVICES; Device++)
+            {
+                /* Enumerate all functions for each devices */
+                for(Function = 0; Function < PCI_MAX_FUNCTION; Function++)
+                {
+                    /* Read configuration space */
+                    Address = ((UINT64)((((UINT_PTR) Bus) << 24) + (((UINT_PTR) Device) << 16) +
+                                        (((UINT_PTR) Function) << 8) + ((UINT_PTR) 0)));
+                    PciDev->Pci.Read(PciDev, 2, Address, sizeof (PciHeader) / sizeof (UINT32), &PciHeader);
+
+                    /* Check if device exists */
+                    if(PciHeader.VendorId == PCI_INVALID_VENDORID)
+                    {
+                        /* Skip non-existen device */
+                        continue;
+                    }
+
+                    /* Check if device is serial controller or multiport serial controller */
+                    if(PciHeader.BaseClass == 0x07 && (PciHeader.SubClass == 0x00 || PciHeader.SubClass == 0x02))
+                    {
+                        /* Enable I/O space access */
+                        Address |= 0x4;
+                        Command = PCI_ENABLE_IO_SPACE;
+                        Status = PciDev->Pci.Write(PciDev, 1, Address, 1, &Command);
+                    }
+                }
+            }
+        }
+    }
+
+    /* Return SUCCESS */
+    return STATUS_EFI_SUCCESS;
+}
+
 /**
  * This routine initializes the COM port debug console.
  *
@@ -136,6 +238,21 @@ BlComPortInitialize()
 
     /* Initialize COM port */
     Status = HlInitializeComPort(&EfiSerialPort, PortNumber, UlongToPtr(PortAddress), BaudRate);
+
+    /* Port not found under supplied address */
+    if(Status == STATUS_NOT_FOUND && PortAddress)
+    {
+        /* This might be PCI(E) serial controller, try to activate I/O space access first */
+        EfiStatus = BlActivateSerialControllerIO();
+        if(EfiStatus == STATUS_EFI_SUCCESS)
+        {
+            /* Try to reinitialize COM port */
+            BlEfiPrint(L"Enabled I/O space access for all PCI(E) serial controllers found\n");
+            Status = HlInitializeComPort(&EfiSerialPort, PortNumber, UlongToPtr(PortAddress), BaudRate);
+        }
+    }
+
+    /* Check COM port initialization status code */
     if(Status != STATUS_SUCCESS)
     {
         /* Serial port initialization failed, mark as not ready */
diff --git a/xtldr/includes/xtbl.h b/xtldr/includes/xtbl.h
index 034edf5..20c7f62 100644
--- a/xtldr/includes/xtbl.h
+++ b/xtldr/includes/xtbl.h
@@ -32,6 +32,10 @@ EXTERN PVOID EfiLoaderStack;
 /* Serial port configuration */
 EXTERN CPPORT EfiSerialPort;
 
+XTCDECL
+EFI_STATUS
+BlActivateSerialControllerIO();
+
 XTCDECL
 EFI_STATUS
 BlAddVirtualMemoryMapping(IN PLIST_ENTRY MemoryMappings,