smp: Implement empty macro for obtaining logical CPU index

This implements empty hooks to the arch/chip layer, which can implement
an optional translation between logical<->physical CPU/core id.

The default mapping is 1:1 i.e. logical=physical.

arch/Kconfig

@@ -417,6 +417,11 @@ config ARCH_HAVE_MULTICPU
 	bool
 	default n
 
+config ARCH_HAVE_CPUID_MAPPING
+	bool
+	default n
+	depends on ARCH_HAVE_MULTICPU
+
 config ARCH_HAVE_FORK
 	bool
 	default n

include/nuttx/arch.h

@@ -111,6 +111,19 @@
 #  define up_cpu_index() 0
 #endif /* CONFIG_ARCH_HAVE_MULTICPU */
 
+/****************************************************************************
+ * Name: up_this_cpu
+ *
+ * Description:
+ *   Return the logical core number. Default implementation is 1:1 mapping,
+ *   i.e. physical=logical.
+ *
+ ****************************************************************************/
+
+#ifndef CONFIG_ARCH_HAVE_CPUID_MAPPING
+#  define up_this_cpu() up_cpu_index()
+#endif
+
 /****************************************************************************
  * Public Types
  ****************************************************************************/

include/nuttx/sched.h

@@ -237,7 +237,7 @@
  */
 
 #ifdef CONFIG_SMP
-#  define this_cpu()                 up_cpu_index()
+#  define this_cpu()                 up_this_cpu()
 #else
 #  define this_cpu()                 (0)
 #endif