arm: psci: save context id for cpu_on PSCI command

Save and use the 3rd parameter of PSCI CPU_ON request: context_id.

The context_id parameter is only meaningful to the caller.
U-Boot PSCI preserves a copy of the value passed in this parameter.
Following wakeup from a  powerdown state, U-BOOT PSCI places
this value in R0 when it first enters the OS.

NB: this context id is not (yet?) used by Linux but it is mandatory
    to be PSCI compliant.

update armv7 psci functions:
- psci_save_target_pc(): keep for backward compatibility with
  current platform (only save PC and force context id to 0)
  => should be removed when all platform migrate to the new API

- psci_save(): new API to use by ARMv7 platform with PSCI,
  save pc (= entry_point_address) and context_id

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com>

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

@@ -25,10 +25,19 @@
 #include <linux/linkage.h>
 
 static u32 psci_target_pc[CONFIG_ARMV7_PSCI_NR_CPUS] __secure_data = { 0 };
+static u32 psci_context_id[CONFIG_ARMV7_PSCI_NR_CPUS] __secure_data = { 0 };
 
 void __secure psci_save_target_pc(int cpu, u32 pc)
 {
 	psci_target_pc[cpu] = pc;
+	psci_context_id[cpu] = 0;
+	dsb();
+}
+
+void __secure psci_save(int cpu, u32 pc, u32 context_id)
+{
+	psci_target_pc[cpu] = pc;
+	psci_context_id[cpu] = context_id;
 	dsb();
 }
 
@@ -37,3 +46,8 @@ u32 __secure psci_get_target_pc(int cpu)
 	return psci_target_pc[cpu];
 }
 
+u32 __secure psci_get_context_id(int cpu)
+{
+	return psci_context_id[cpu];
+}
+

arch/arm/cpu/armv7/psci.S

@@ -327,6 +327,10 @@ ENTRY(psci_cpu_entry)
 	bl	_nonsec_init
 
 	bl	psci_get_cpu_id			@ CPU ID => r0
+	mov	r2, r0				@ CPU ID => r2
+	bl	psci_get_context_id		@ context id => r0
+	mov	r1, r0				@ context id => r1
+	mov	r0, r2				@ CPU ID => r0
 	bl	psci_get_target_pc		@ target PC => r0
 	b	_do_nonsec_entry
 ENDPROC(psci_cpu_entry)

arch/arm/include/asm/psci.h

@@ -93,9 +93,11 @@
 #ifndef __ASSEMBLY__
 #include <asm/types.h>
 
-/* These 2 helper functions assume cpu < CONFIG_ARMV7_PSCI_NR_CPUS */
+/* These 4 helper functions assume cpu < CONFIG_ARMV7_PSCI_NR_CPUS */
 u32 psci_get_target_pc(int cpu);
+u32 psci_get_context_id(int cpu);
 void psci_save_target_pc(int cpu, u32 pc);
+void psci_save(int cpu, u32 pc, u32 context_id);
 
 void psci_cpu_entry(void);
 u32 psci_get_cpu_id(void);