arm64: Add support for save/restore registers for CPU startup.

startup.c provides function to enable CPU in any stage to save register data
that can be used by secondary CPU (for normal boot) or any CPU (for resume
boot). stage_entry.S defines space for saving arm64_startup_data. This can be
filled by:
1) Primary CPU before bringing up secondary CPUs so that the secondary can use
register values to initialize MMU-related and other required registers to
appropriate values.
2) CPU suspend path to ensure that on resume the values which were saved are
restored appropriately.

stage_entry.S provides a common path for both normal and resume boot to
initialize saved registers. For resume path, it is important to set the
secondary entry point for startup since x26 needs to be 1 for enabling MMU and
cache.

This also ensures that we do not fall into false memory cache errors which
caused CPU to fail during normal / resume boot. Thus, we can get rid of the
stack cache invalidate for secondary CPUs.

BUG=chrome-os-partner:33962
BRANCH=None
TEST=Compiles and boots both CPU0 and CPU1 on ryu without mmu_enable and stack
cache invalidate for CPU1.

Change-Id: Ia4ca0e7d35c0738dbbaa926cce4268143c6f9de3
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 9f5e78469313ddd144ad7cf5abc3e07cb712183a
Original-Signed-off-by: Furquan Shaikh <furquan@google.com>
Original-Change-Id: I527a95779cf3fed37392b6605b096f54f8286d64
Original-Reviewed-on: https://chromium-review.googlesource.com/231561
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Original-Tested-by: Furquan Shaikh <furquan@chromium.org>
Original-Commit-Queue: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: http://review.coreboot.org/9540
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

2 files changed, 57 insertions, 0 deletions

diff --git a/src/arch/arm64/include/arch/startup.h b/src/arch/arm64/include/arch/startup.h
new file mode 100644
index 0000000000..bb3a863754
--- /dev/null
+++ b/src/arch/arm64/include/arch/startup.h
@@ -0,0 +1,46 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2014 Google Inc
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; version 2 of
+ * the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+ * MA 02110-1301 USA
+ */
+
+#ifndef __ARCH_ARM64_INCLUDE_ARCH_STARTUP_H__
+#define __ARCH_ARM64_INCLUDE_ARCH_STARTUP_H__
+
+/* Every element occupies 8 bytes (64-bit entries) */
+#define PER_ELEMENT_SIZE_BYTES		8
+#define MAIR_INDEX			0
+#define TCR_INDEX			1
+#define TTBR0_INDEX			2
+#define SCR_INDEX			3
+#define VBAR_INDEX			4
+/* IMPORTANT!!! If any new element is added please update NUM_ELEMENTS */
+#define NUM_ELEMENTS			5
+
+#ifndef __ASSEMBLY__
+
+/*
+ * startup_save_cpu_data is used to save register values that need to be setup
+ * when a CPU starts booting. This is used by secondary CPUs as well as resume
+ * path to directly setup MMU and other related registers.
+ */
+void startup_save_cpu_data(void);
+
+#endif
+
+#endif /* __ARCH_ARM64_INCLUDE_ARCH_STARTUP_H__ */
diff --git a/src/arch/arm64/include/armv8/arch/cpu.h b/src/arch/arm64/include/armv8/arch/cpu.h
index d968a06fe4..34220d9792 100644
--- a/src/arch/arm64/include/armv8/arch/cpu.h
+++ b/src/arch/arm64/include/armv8/arch/cpu.h
@@ -170,4 +170,15 @@ static inline void *secondary_entry_point(void *e)
  */
 void arm64_cpu_startup(void);
 
+/*
+ * The arm64_cpu_startup_resume() initializes a CPU's exception stack and
+ * regular stack as well initializing the C environment for the processor. It
+ * calls into the array of function pointers at symbol c_entry depending
+ * on BSP state. Note that arm64_cpu_startup contains secondary entry
+ * point which can be obtained by secondary_entry_point().
+ * Additionally, it also restores saved register data and enables MMU, caches
+ * and exceptions before jumping to C environment for both BSP and non-BSP CPUs.
+ */
+void arm64_cpu_startup_resume(void);
+
 #endif /* __ARCH_CPU_H__ */