PSCI: Introduce new platform and CM helper APIs

This patch introduces new platform APIs and context management helper APIs
to support the new topology framework based on linear core position. This
framework will be introduced in the follwoing patch and it removes the
assumption that the MPIDR based affinity levels map directly to levels
in a power domain tree. The new platforms APIs and context management
helpers based on core position are as described below:

* plat_my_core_pos() and plat_core_pos_by_mpidr()

These 2 new mandatory platform APIs are meant to replace the existing
'platform_get_core_pos()' API. The 'plat_my_core_pos()' API returns the
linear index of the calling core and 'plat_core_pos_by_mpidr()' returns
the linear index of a core specified by its MPIDR. The latter API will also
validate the MPIDR passed as an argument and will return an error code (-1)
if an invalid MPIDR is passed as the argument. This enables the caller to
safely convert an MPIDR of another core to its linear index without querying
the PSCI topology tree e.g. during a call to PSCI CPU_ON.

Since the 'plat_core_pos_by_mpidr()' API verifies an MPIDR, which is always
platform specific, it is no longer possible to maintain a default implementation
of this API. Also it might not be possible for a platform port to verify an
MPIDR before the C runtime has been setup or the topology has been initialized.
This would prevent 'plat_core_pos_by_mpidr()' from being callable prior to
topology setup. As a result, the generic Trusted Firmware code does not call
this API before the topology setup has been done.

The 'plat_my_core_pos' API should be able to run without a C runtime.
Since this API needs to return a core position which is equal to the one
returned by 'plat_core_pos_by_mpidr()' API for the corresponding MPIDR,
this too cannot have default implementation and is a mandatory API for
platform ports. These APIs will be implemented by the ARM reference platform
ports later in the patch stack.

* plat_get_my_stack() and plat_set_my_stack()

These APIs are the stack management APIs which set/return stack addresses
appropriate for the calling core. These replace the 'platform_get_stack()' and
'platform_set_stack()' APIs. A default weak MP version and a global UP version
of these APIs are provided for the platforms.

* Context management helpers based on linear core position

A set of new context management(CM) helpers viz cm_get_context_by_index(),
cm_set_context_by_index(), cm_init_my_context() and cm_init_context_by_index()
are defined which are meant to replace the old helpers which took MPIDR
as argument. The old CM helpers are implemented based on the new helpers to
allow for code consolidation and will be deprecated once the switch to the new
framework is done.

Change-Id: I89758632b370c2812973a4b2efdd9b81a41f9b69

2 files changed, 39 insertions, 5 deletions

diff --git a/plat/common/aarch64/platform_mp_stack.S b/plat/common/aarch64/platform_mp_stack.S
index 7a98d290..0cea9ac3 100644
--- a/plat/common/aarch64/platform_mp_stack.S
+++ b/plat/common/aarch64/platform_mp_stack.S
@@ -36,7 +36,8 @@
 	.local	platform_normal_stacks
 	.weak	platform_set_stack
 	.weak	platform_get_stack
-
+	.weak	plat_get_my_stack
+	.weak	plat_set_my_stack
 
 	/* -----------------------------------------------------
 	 * unsigned long platform_get_stack (unsigned long mpidr)
@@ -66,6 +67,33 @@ func platform_set_stack
 endfunc platform_set_stack
 
 	/* -----------------------------------------------------
+	 * unsigned long plat_get_my_stack ()
+	 *
+	 * For the current CPU, this function returns the stack
+	 * pointer for a stack allocated in device memory.
+	 * -----------------------------------------------------
+	 */
+func plat_get_my_stack
+	mov	x10, x30 // lr
+	get_my_mp_stack platform_normal_stacks, PLATFORM_STACK_SIZE
+	ret	x10
+endfunc plat_get_my_stack
+
+	/* -----------------------------------------------------
+	 * void plat_set_my_stack ()
+	 *
+	 * For the current CPU, this function sets the stack
+	 * pointer to a stack allocated in normal memory.
+	 * -----------------------------------------------------
+	 */
+func plat_set_my_stack
+	mov	x9, x30 // lr
+	bl 	plat_get_my_stack
+	mov	sp, x0
+	ret	x9
+endfunc plat_set_my_stack
+
+	/* -----------------------------------------------------
 	 * Per-cpu stacks in normal memory. Each cpu gets a
 	 * stack of PLATFORM_STACK_SIZE bytes.
 	 * -----------------------------------------------------
diff --git a/plat/common/aarch64/platform_up_stack.S b/plat/common/aarch64/platform_up_stack.S
index ea6641a7..d6d6c6e2 100644
--- a/plat/common/aarch64/platform_up_stack.S
+++ b/plat/common/aarch64/platform_up_stack.S
@@ -34,10 +34,13 @@
 
 
 	.local	platform_normal_stacks
+	.globl	plat_set_my_stack
+	.globl	plat_get_my_stack
 	.globl	platform_set_stack
 	.globl	platform_get_stack
 
 	/* -----------------------------------------------------
+	 * unsigned long plat_get_my_stack ()
 	 * unsigned long platform_get_stack (unsigned long)
 	 *
 	 * For cold-boot BL images, only the primary CPU needs a
@@ -45,12 +48,14 @@
 	 * stack allocated in device memory.
 	 * -----------------------------------------------------
 	 */
-func platform_get_stack
+func plat_get_my_stack
+platform_get_stack:
 	get_up_stack platform_normal_stacks, PLATFORM_STACK_SIZE
 	ret
-endfunc platform_get_stack
+endfunc plat_get_my_stack
 
 	/* -----------------------------------------------------
+	 * void plat_set_my_stack ()
 	 * void platform_set_stack (unsigned long)
 	 *
 	 * For cold-boot BL images, only the primary CPU needs a
@@ -58,11 +63,12 @@ endfunc platform_get_stack
 	 * allocated in normal memory.
 	 * -----------------------------------------------------
 	 */
-func platform_set_stack
+func plat_set_my_stack
+platform_set_stack:
 	get_up_stack platform_normal_stacks, PLATFORM_STACK_SIZE
 	mov sp, x0
 	ret
-endfunc platform_set_stack
+endfunc plat_set_my_stack
 
 	/* -----------------------------------------------------
 	 * Single cpu stack in normal memory.