[PATCH v3 22/27] Ovmf/Xen: add Xen PV console SerialPortLib driver

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

This implements a SerialPortLib instance that wires up to the
PV console ring used by domU guests. Also imports the required
upstream Xen io/console.h header.

Contributed-under: TianoCore Contribution Agreement 1.0
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 OvmfPkg/Include/IndustryStandard/Xen/io/console.h  |  51 +++++++
 .../XenConsoleSerialPortLib.c                      | 156 +++++++++++++++++++++
 .../XenConsoleSerialPortLib.inf                    |  35 +++++
 3 files changed, 242 insertions(+)
 create mode 100644 OvmfPkg/Include/IndustryStandard/Xen/io/console.h
 create mode 100644 OvmfPkg/Library/XenConsoleSerialPortLib/XenConsoleSerialPortLib.c
 create mode 100644 OvmfPkg/Library/XenConsoleSerialPortLib/XenConsoleSerialPortLib.inf

diff --git a/OvmfPkg/Include/IndustryStandard/Xen/io/console.h b/OvmfPkg/Include/IndustryStandard/Xen/io/console.h
new file mode 100644
index 000000000000..f1caa9765bcf
--- /dev/null
+++ b/OvmfPkg/Include/IndustryStandard/Xen/io/console.h
@@ -0,0 +1,51 @@
+/******************************************************************************
+ * console.h
+ *
+ * Console I/O interface for Xen guest OSes.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * Copyright (c) 2005, Keir Fraser
+ */
+
+#ifndef __XEN_PUBLIC_IO_CONSOLE_H__
+#define __XEN_PUBLIC_IO_CONSOLE_H__
+
+typedef UINT32 XENCONS_RING_IDX;
+
+#define MASK_XENCONS_IDX(idx, ring) ((idx) & (sizeof(ring)-1))
+
+struct xencons_interface {
+    char in[1024];
+    char out[2048];
+    XENCONS_RING_IDX in_cons, in_prod;
+    XENCONS_RING_IDX out_cons, out_prod;
+};
+
+#endif /* __XEN_PUBLIC_IO_CONSOLE_H__ */
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/OvmfPkg/Library/XenConsoleSerialPortLib/XenConsoleSerialPortLib.c b/OvmfPkg/Library/XenConsoleSerialPortLib/XenConsoleSerialPortLib.c
new file mode 100644
index 000000000000..98022354cf31
--- /dev/null
+++ b/OvmfPkg/Library/XenConsoleSerialPortLib/XenConsoleSerialPortLib.c
@@ -0,0 +1,156 @@
+/** @file
+  Xen console SerialPortLib instance
+
+  Copyright (c) 2015, Linaro Ltd. All rights reserved.<BR>
+
+  This program and the accompanying materials
+  are licensed and made available under the terms and conditions of the BSD License
+  which accompanies this distribution.  The full text of the license may be found at
+  http://opensource.org/licenses/bsd-license.php
+
+  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+
+**/
+
+#include <Base.h>
+#include <Uefi/UefiBaseType.h>
+
+#include <Library/BaseLib.h>
+#include <Library/SerialPortLib.h>
+#include <Library/XenHypercallLib.h>
+
+#include <IndustryStandard/Xen/io/console.h>
+#include <IndustryStandard/Xen/hvm/params.h>
+#include <IndustryStandard/Xen/event_channel.h>
+
+//
+// The code below expects these global variables to be mutable, even in the case
+// that we have been incorporated into SEC or PEIM phase modules (which is
+// allowed by our INF description). While this is a dangerous assumption to make
+// in general, it is actually fine for the Xen domU (guest) environment that
+// this module is intended for, as UEFI always executes from DRAM in that case.
+//
+STATIC evtchn_send_t              mXenConsoleEventChain;
+STATIC struct xencons_interface   *mXenConsoleInterface;
+
+RETURN_STATUS
+EFIAPI
+SerialPortInitialize (
+  VOID
+  )
+{
+  if (!mXenConsoleInterface) {
+    mXenConsoleEventChain.port = (UINT32)XenHypercallHvmGetParam (HVM_PARAM_CONSOLE_EVTCHN);
+    mXenConsoleInterface = (struct xencons_interface *)(UINTN)
+      (XenHypercallHvmGetParam (HVM_PARAM_CONSOLE_PFN) << EFI_PAGE_SHIFT);
+
+    //
+    // No point in ASSERT'ing here as we won't be seeing the output
+    //
+  }
+  return RETURN_SUCCESS;
+}
+
+/**
+  Write data to serial device.
+
+  @param  Buffer           Point of data buffer which need to be written.
+  @param  NumberOfBytes    Number of output bytes which are cached in Buffer.
+
+  @retval 0                Write data failed.
+  @retval !0               Actual number of bytes written to serial device.
+
+**/
+UINTN
+EFIAPI
+SerialPortWrite (
+  IN UINT8     *Buffer,
+  IN UINTN     NumberOfBytes
+  )
+{
+  XENCONS_RING_IDX  Consumer, Producer;
+  UINTN             Sent;
+
+  if (!mXenConsoleInterface) {
+    return 0;
+  }
+
+  Consumer = mXenConsoleInterface->out_cons;
+  Producer = mXenConsoleInterface->out_prod;
+
+  MemoryFence ();
+
+  Sent = 0;
+  while (Sent < NumberOfBytes && ((Producer - Consumer) < sizeof (mXenConsoleInterface->out)))
+    mXenConsoleInterface->out[MASK_XENCONS_IDX(Producer++, mXenConsoleInterface->out)] = Buffer[Sent++];
+
+  MemoryFence ();
+
+  mXenConsoleInterface->out_prod = Producer;
+
+  if (Sent > 0) {
+    XenHypercallEventChannelOp (EVTCHNOP_send, &mXenConsoleEventChain);
+  }
+
+  return Sent;
+}
+
+/**
+  Read data from serial device and save the data in buffer.
+
+  @param  Buffer           Point of data buffer which need to be written.
+  @param  NumberOfBytes    Size of Buffer[].
+
+  @retval 0                Read data failed.
+  @retval !0               Actual number of bytes read from serial device.
+
+**/
+UINTN
+EFIAPI
+SerialPortRead (
+  OUT UINT8     *Buffer,
+  IN  UINTN     NumberOfBytes
+)
+{
+  XENCONS_RING_IDX  Consumer, Producer;
+  UINTN             Received;
+
+  if (!mXenConsoleInterface) {
+    return 0;
+  }
+
+  Consumer = mXenConsoleInterface->in_cons;
+  Producer = mXenConsoleInterface->in_prod;
+
+  MemoryFence ();
+
+  Received = 0;
+  while (Received < NumberOfBytes && Consumer < Producer)
+     Buffer[Received++] = mXenConsoleInterface->in[MASK_XENCONS_IDX(Consumer++, mXenConsoleInterface->in)];
+
+  MemoryFence ();
+
+  mXenConsoleInterface->in_cons = Consumer;
+
+  XenHypercallEventChannelOp (EVTCHNOP_send, &mXenConsoleEventChain);
+
+  return Received;
+}
+
+/**
+  Check to see if any data is available to be read from the debug device.
+
+  @retval TRUE       At least one byte of data is available to be read
+  @retval FALSE      No data is available to be read
+
+**/
+BOOLEAN
+EFIAPI
+SerialPortPoll (
+  VOID
+  )
+{
+  return mXenConsoleInterface &&
+    mXenConsoleInterface->in_cons != mXenConsoleInterface->in_prod;
+}
diff --git a/OvmfPkg/Library/XenConsoleSerialPortLib/XenConsoleSerialPortLib.inf b/OvmfPkg/Library/XenConsoleSerialPortLib/XenConsoleSerialPortLib.inf
new file mode 100644
index 000000000000..8a7411558fa3
--- /dev/null
+++ b/OvmfPkg/Library/XenConsoleSerialPortLib/XenConsoleSerialPortLib.inf
@@ -0,0 +1,35 @@
+#/** @file
+#
+#  Component description file for XenConsoleSerialPortLib module
+#
+#  Copyright (c) 2015, Linaro Ltd. All rights reserved.<BR>
+#
+#  This program and the accompanying materials
+#  are licensed and made available under the terms and conditions of the BSD License
+#  which accompanies this distribution.  The full text of the license may be found at
+#  http://opensource.org/licenses/bsd-license.php
+#
+#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+#
+#**/
+
+[Defines]
+  INF_VERSION                    = 0x00010005
+  BASE_NAME                      = XenConsoleSerialPortLib
+  FILE_GUID                      = 401406DD-BCAC-4B91-9F4E-72A7FEBE4762
+  MODULE_TYPE                    = BASE
+  VERSION_STRING                 = 1.0
+  LIBRARY_CLASS                  = SerialPortLib
+  CONSTRUCTOR                    = SerialPortInitialize
+
+[Sources.common]
+  XenConsoleSerialPortLib.c
+
+[LibraryClasses]
+  BaseLib
+  XenHypercallLib
+
+[Packages]
+  MdePkg/MdePkg.dec
+  OvmfPkg/OvmfPkg.dec
-- 
1.8.3.2