ARM: Introduce CPU_METHOD_OF_DECLARE() for cpu hotplug/smp

The goal of multi-platform kernels is to remove the need for mach
directories and machine descriptors. To further that goal,
introduce CPU_METHOD_OF_DECLARE() to allow cpu hotplug/smp
support to be separated from the machine descriptors.
Implementers should specify an enable-method property in their
cpus node and then implement a matching set of smp_ops in their
hotplug/smp code, wiring it up with the CPU_METHOD_OF_DECLARE()
macro. When the kernel is compiled we'll collect all the
enable-method smp_ops into one section for use at boot.

At boot time we'll look for an enable-method in each cpu node and
try to match that against all known CPU enable methods in the
kernel. If there are no enable-methods in the cpu nodes we
fallback to the cpus node and try to use any enable-method found
there. If that doesn't work we fall back to the old way of using
the machine descriptor.

Acked-by: Mark Rutland <mark.rutland@arm.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: <devicetree@vger.kernel.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Kumar Gala <galak@codeaurora.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index bc2121fa9132..bd02ca7a1d55 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -167,6 +167,15 @@
 #define CLK_OF_TABLES()
 #endif
 
+#ifdef CONFIG_SMP
+#define CPU_METHOD_OF_TABLES() . = ALIGN(8);                                \
+                           VMLINUX_SYMBOL(__cpu_method_of_table_begin) = .; \
+                           *(__cpu_method_of_table)                         \
+                           VMLINUX_SYMBOL(__cpu_method_of_table_end) = .;
+#else
+#define CPU_METHOD_OF_TABLES()
+#endif
+
 #define KERNEL_DTB()                                                    \
         STRUCT_ALIGN();                                                 \
         VMLINUX_SYMBOL(__dtb_start) = .;                                \
@@ -491,6 +500,7 @@
         MEM_DISCARD(init.rodata)                                        \
         CLK_OF_TABLES()                                                 \
         CLKSRC_OF_TABLES()                                              \
+        CPU_METHOD_OF_TABLES()                                          \
         KERNEL_DTB()                                                    \
         IRQCHIP_OF_MATCH_TABLE()