Support for NXP's i.MX8 SoCs IPC

NXP's i.MX8 SoCs have system controller (M4 core)
which takes control of clock management, power management,
partition management, PAD management etc., other
clusters like Cortex-A35 can send out command via MU
(Message Unit) to system controller for clock/power
management etc..

This patch adds basic IPC(inter-processor communication) support.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
diff --git a/plat/imx/common/include/sci/sci_rpc.h b/plat/imx/common/include/sci/sci_rpc.h
new file mode 100644
index 0000000..052f361
--- /dev/null
+++ b/plat/imx/common/include/sci/sci_rpc.h
@@ -0,0 +1,127 @@
+/*
+ * Copyright (c) 2015-2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+/*!
+ * Header file for the RPC implementation.
+ */
+
+#ifndef SC_RPC_H
+#define SC_RPC_H
+
+/* Includes */
+
+#include <sci/sci_types.h>
+#include <sci/sci_ipc.h>
+#include <stdbool.h>
+
+/* Defines */
+
+#define SC_RPC_VERSION          1U
+
+#define SC_RPC_MAX_MSG          8U
+
+#define RPC_VER(MSG)            ((MSG)->version)
+#define RPC_SIZE(MSG)           ((MSG)->size)
+#define RPC_SVC(MSG)            ((MSG)->svc)
+#define RPC_FUNC(MSG)           ((MSG)->func)
+#define RPC_R8(MSG)             ((MSG)->func)
+#define RPC_I32(MSG, IDX)       ((MSG)->DATA.i32[(IDX) / 4U])
+#define RPC_I16(MSG, IDX)       ((MSG)->DATA.i16[(IDX) / 2U])
+#define RPC_I8(MSG, IDX)        ((MSG)->DATA.i8[(IDX)])
+#define RPC_U32(MSG, IDX)       ((MSG)->DATA.u32[(IDX) / 4U])
+#define RPC_U16(MSG, IDX)       ((MSG)->DATA.u16[(IDX) / 2U])
+#define RPC_U8(MSG, IDX)        ((MSG)->DATA.u8[(IDX)])
+
+#define SC_RPC_SVC_UNKNOWN      0U
+#define SC_RPC_SVC_RETURN       1U
+#define SC_RPC_SVC_PM           2U
+#define SC_RPC_SVC_RM           3U
+#define SC_RPC_SVC_TIMER        5U
+#define SC_RPC_SVC_PAD          6U
+#define SC_RPC_SVC_MISC         7U
+#define SC_RPC_SVC_IRQ          8U
+#define SC_RPC_SVC_ABORT        9U
+
+#define SC_RPC_ASYNC_STATE_RD_START      0U
+#define SC_RPC_ASYNC_STATE_RD_ACTIVE     1U
+#define SC_RPC_ASYNC_STATE_RD_DONE       2U
+#define SC_RPC_ASYNC_STATE_WR_START      3U
+#define SC_RPC_ASYNC_STATE_WR_ACTIVE     4U
+#define SC_RPC_ASYNC_STATE_WR_DONE       5U
+
+#define SC_RPC_MU_GIR_SVC       0x1U
+#define SC_RPC_MU_GIR_DBG       0x8U
+
+/* Types */
+
+typedef uint8_t sc_rpc_svc_t;
+
+typedef struct sc_rpc_msg_s {
+	uint8_t version;
+	uint8_t size;
+	uint8_t svc;
+	uint8_t func;
+	union {
+		int32_t i32[(SC_RPC_MAX_MSG - 1U)];
+		int16_t i16[(SC_RPC_MAX_MSG - 1U) * 2U];
+		int8_t i8[(SC_RPC_MAX_MSG - 1U) * 4U];
+		uint32_t u32[(SC_RPC_MAX_MSG - 1U)];
+		uint16_t u16[(SC_RPC_MAX_MSG - 1U) * 2U];
+		uint8_t u8[(SC_RPC_MAX_MSG - 1U) * 4U];
+	} DATA;
+} sc_rpc_msg_t;
+
+typedef uint8_t sc_rpc_async_state_t;
+
+typedef struct sc_rpc_async_msg_s {
+	sc_rpc_async_state_t state;
+	uint8_t wordIdx;
+	sc_rpc_msg_t msg;
+	uint32_t timeStamp;
+} sc_rpc_async_msg_t;
+
+/* Functions */
+
+/*!
+ * This is an internal function to send an RPC message over an IPC
+ * channel. It is called by client-side SCFW API function shims.
+ *
+ * @param[in]     ipc         IPC handle
+ * @param[in,out] msg         handle to a message
+ * @param[in]     no_resp     response flag
+ *
+ * If \a no_resp is SC_FALSE then this function waits for a response
+ * and returns the result in \a msg.
+ */
+void sc_call_rpc(sc_ipc_t ipc, sc_rpc_msg_t *msg, bool no_resp);
+
+/*!
+ * This is an internal function to dispath an RPC call that has
+ * arrived via IPC over an MU. It is called by server-side SCFW.
+ *
+ * @param[in]     mu          MU message arrived on
+ * @param[in,out] msg         handle to a message
+ *
+ * The function result is returned in \a msg.
+ */
+void sc_rpc_dispatch(sc_rsrc_t mu, sc_rpc_msg_t *msg);
+
+/*!
+ * This function translates an RPC message and forwards on to the
+ * normal RPC API.  It is used only by hypervisors.
+ *
+ * @param[in]     ipc         IPC handle
+ * @param[in,out] msg         handle to a message
+ *
+ * This function decodes a message, calls macros to translate the
+ * resources, pads, addresses, partitions, memory regions, etc. and
+ * then forwards on to the hypervisors SCFW API.Return results are
+ * translated back abd placed back into the message to be returned
+ * to the original API.
+ */
+void sc_rpc_xlate(sc_ipc_t ipc, sc_rpc_msg_t *msg);
+
+#endif				/* SC_RPC_H */