Introduce PSCI Library Interface

This patch introduces the PSCI Library interface. The major changes
introduced are as follows:

* Earlier BL31 was responsible for Architectural initialization during cold
boot via bl31_arch_setup() whereas PSCI was responsible for the same during
warm boot. This functionality is now consolidated by the PSCI library
and it does Architectural initialization via psci_arch_setup() during both
cold and warm boots.

* Earlier the warm boot entry point was always `psci_entrypoint()`. This was
not flexible enough as a library interface. Now PSCI expects the runtime
firmware to provide the entry point via `psci_setup()`. A new function
`bl31_warm_entrypoint` is introduced in BL31 and the previous
`psci_entrypoint()` is deprecated.

* The `smc_helpers.h` is reorganized to separate the SMC Calling Convention
defines from the Trusted Firmware SMC helpers. The former is now in a new
header file `smcc.h` and the SMC helpers are moved to Architecture specific
header.

* The CPU context is used by PSCI for context initialization and
restoration after power down (PSCI Context). It is also used by BL31 for SMC
handling and context management during Normal-Secure world switch (SMC
Context). The `psci_smc_handler()` interface is redefined to not use SMC
helper macros thus enabling to decouple the PSCI context from EL3 runtime
firmware SMC context. This enables PSCI to be integrated with other runtime
firmware using a different SMC context.

NOTE: With this patch the architectural setup done in `bl31_arch_setup()`
is done as part of `psci_setup()` and hence `bl31_platform_setup()` will be
invoked prior to architectural setup. It is highly unlikely that the platform
setup will depend on architectural setup and cause any failure. Please be
be aware of this change in sequence.

Change-Id: I7f497a08d33be234bbb822c28146250cb20dab73
diff --git a/include/lib/aarch64/smcc_helpers.h b/include/lib/aarch64/smcc_helpers.h
new file mode 100644
index 0000000..617a5bc
--- /dev/null
+++ b/include/lib/aarch64/smcc_helpers.h
@@ -0,0 +1,86 @@
+/*
+ * Copyright (c) 2015-2016, ARM Limited and Contributors. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * Neither the name of ARM nor the names of its contributors may be used
+ * to endorse or promote products derived from this software without specific
+ * prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef __SMCC_HELPERS_H__
+#define __SMCC_HELPERS_H__
+
+#include <smcc.h>
+
+#ifndef __ASSEMBLY__
+#include <context.h>
+
+/* Convenience macros to return from SMC handler */
+#define SMC_RET0(_h)	{					\
+	return (uint64_t) (_h);					\
+}
+#define SMC_RET1(_h, _x0)	{				\
+	write_ctx_reg(get_gpregs_ctx(_h), CTX_GPREG_X0, (_x0));	\
+	SMC_RET0(_h);						\
+}
+#define SMC_RET2(_h, _x0, _x1)	{				\
+	write_ctx_reg(get_gpregs_ctx(_h), CTX_GPREG_X1, (_x1));	\
+	SMC_RET1(_h, (_x0));					\
+}
+#define SMC_RET3(_h, _x0, _x1, _x2)	{			\
+	write_ctx_reg(get_gpregs_ctx(_h), CTX_GPREG_X2, (_x2));	\
+	SMC_RET2(_h, (_x0), (_x1));				\
+}
+#define SMC_RET4(_h, _x0, _x1, _x2, _x3)	{		\
+	write_ctx_reg(get_gpregs_ctx(_h), CTX_GPREG_X3, (_x3));	\
+	SMC_RET3(_h, (_x0), (_x1), (_x2));			\
+}
+
+/*
+ * Convenience macros to access general purpose registers using handle provided
+ * to SMC handler. These take the offset values defined in context.h
+ */
+#define SMC_GET_GP(_h, _g)					\
+	read_ctx_reg(get_gpregs_ctx(_h), (_g))
+#define SMC_SET_GP(_h, _g, _v)					\
+	write_ctx_reg(get_gpregs_ctx(_h), (_g), (_v))
+
+/*
+ * Convenience macros to access EL3 context registers using handle provided to
+ * SMC handler. These take the offset values defined in context.h
+ */
+#define SMC_GET_EL3(_h, _e)					\
+	read_ctx_reg(get_el3state_ctx(_h), (_e))
+#define SMC_SET_EL3(_h, _e, _v)					\
+	write_ctx_reg(get_el3state_ctx(_h), (_e), (_v))
+
+/* Return a UUID in the SMC return registers */
+#define SMC_UUID_RET(_h, _uuid)					\
+	SMC_RET4(handle, ((const uint32_t *) &(_uuid))[0],	\
+			 ((const uint32_t *) &(_uuid))[1],	\
+			 ((const uint32_t *) &(_uuid))[2],	\
+			 ((const uint32_t *) &(_uuid))[3])
+
+#endif /*__ASSEMBLY__*/
+#endif /* __SMCC_HELPERS_H__ */