Abstract UART.

Let different toolchains use different implementations of console driver.

Bug: 115484857
Change-Id: I230c2c2dc2570c55eead4eed597663e52160f064
diff --git a/inc/hf/plat/console.h b/inc/hf/plat/console.h
new file mode 100644
index 0000000..604ac26
--- /dev/null
+++ b/inc/hf/plat/console.h
@@ -0,0 +1,32 @@
+/*
+ * Copyright 2018 The Hafnium Authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "hf/mpool.h"
+#include "hf/vm.h"
+
+/** Initialises the console hardware. */
+void plat_console_init(void);
+
+/** Initialises any memory mappings that the console driver needs. */
+void plat_console_mm_init(struct mpool *ppool);
+
+/** Initialises any per-VM memory mappings that the console driver needs. */
+void plat_console_vm_mm_init(struct vm *vm, struct mpool *ppool);
+
+/** Puts a single character on the console. */
+void plat_console_putchar(char c);