audk/OvmfPkg/Library/PlatformDebugLibIoPort/DebugLibDetect.c

67 lines
1.6 KiB
C

/** @file
Detection code for hypervisor debug port.
Non-SEC instance, caches the result of detection.
Copyright (c) 2017, Red Hat, Inc.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include <Base.h>
#include "DebugLibDetect.h"
//
// Set to TRUE if the debug I/O port has been checked
//
STATIC BOOLEAN mDebugIoPortChecked = FALSE;
//
// Set to TRUE if the debug I/O port is enabled
//
STATIC BOOLEAN mDebugIoPortFound = FALSE;
/**
This constructor function must not do anything.
Some modules consuming this library instance, such as the DXE Core, invoke
the DEBUG() macro before they explicitly call
ProcessLibraryConstructorList(). Therefore the auto-generated call from
ProcessLibraryConstructorList() to this constructor function may be preceded
by some calls to PlatformDebugLibIoPortFound() below. Hence
PlatformDebugLibIoPortFound() must not rely on anything this constructor
could set up.
@retval RETURN_SUCCESS The constructor always returns RETURN_SUCCESS.
**/
RETURN_STATUS
EFIAPI
PlatformDebugLibIoPortConstructor (
VOID
)
{
return RETURN_SUCCESS;
}
/**
At the first call, check if the debug I/O port device is present, and cache
the result for later use. At subsequent calls, return the cached result.
@retval TRUE if the debug I/O port device was detected.
@retval FALSE otherwise
**/
BOOLEAN
EFIAPI
PlatformDebugLibIoPortFound (
VOID
)
{
if (!mDebugIoPortChecked) {
mDebugIoPortFound = PlatformDebugLibIoPortDetect ();
mDebugIoPortChecked = TRUE;
}
return mDebugIoPortFound;
}