ARM: PSCI: Add helper functions to access per-CPU target PC storage

Now that we have a data section, add helper functions to save and fetch
per-CPU target PC.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

arch/arm/cpu/armv7/Makefile

@@ -19,7 +19,7 @@ endif
 endif
 
 obj-$(CONFIG_ARMV7_NONSEC)	+= nonsec_virt.o virt-v7.o virt-dt.o
-obj-$(CONFIG_ARMV7_PSCI)	+= psci.o
+obj-$(CONFIG_ARMV7_PSCI)	+= psci.o psci-common.o
 
 obj-$(CONFIG_IPROC) += iproc-common/
 obj-$(CONFIG_KONA) += kona-common/

arch/arm/cpu/armv7/psci-common.c

@@ -0,0 +1,39 @@
+/*
+ * Common PSCI functions
+ *
+ * Copyright (C) 2016 Chen-Yu Tsai
+ * Author: Chen-Yu Tsai <wens@csie.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <asm/armv7.h>
+#include <asm/macro.h>
+#include <asm/psci.h>
+#include <asm/secure.h>
+#include <linux/linkage.h>
+
+static u32 psci_target_pc[CONFIG_ARMV7_PSCI_NR_CPUS] __secure_data = { 0 };
+
+void __secure psci_save_target_pc(int cpu, u32 pc)
+{
+	psci_target_pc[cpu] = pc;
+	DSB;
+}
+
+u32 __secure psci_get_target_pc(int cpu)
+{
+	return psci_target_pc[cpu];
+}
+

arch/arm/include/asm/psci.h

@@ -54,6 +54,10 @@
 #ifndef __ASSEMBLY__
 #include <asm/types.h>
 
+/* These 2 helper functions assume cpu < CONFIG_ARMV7_PSCI_NR_CPUS */
+u32 psci_get_target_pc(int cpu);
+void psci_save_target_pc(int cpu, u32 pc);
+
 void psci_cpu_entry(void);
 u32 psci_get_cpu_id(void);
 u32 psci_get_cpu_stack_top(int cpu);