ARC: smp: Introduce smp hook @init_early_smp for Master core

This adds a platform agnostic early SMP init hook which is called on
Master core before calling setup_processor()

  setup_arch()
     smp_init_cpus()
         smp_ops.init_early_smp()
     ...
     setup_processor()

How this helps:
 - Used for one time init of certain SMP centric IP blocks, before
   calling setup_processor() which probes various bits of core,
   possibly including this block

 - Currently platforms need to call this IP block init from their
   init routines, which doesn't make sense as this is specific to ARC
   core and not platform and otherwise requires copy/paste in all
   (and hence a possible point of failure)

e.g. MCIP init is called from 2 platforms currently (axs10x and sim)
which will go away once we have this.

This change only adds the hooks but they are empty for now. Next commit
will populate them and remove the explicit init calls from platforms.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

1 files changed, 10 insertions, 2 deletions

diff --git a/arch/arc/kernel/smp.c b/arch/arc/kernel/smp.c
index f6175fc5f2bb..a59a53f98877 100644
--- a/arch/arc/kernel/smp.c
+++ b/arch/arc/kernel/smp.c
@@ -42,8 +42,13 @@ void __init smp_prepare_boot_cpu(void)
 }
 
 /*
- * Initialise the CPU possible map early - this describes the CPUs
- * which may be present or become present in the system.
+ * Called from setup_arch() before calling setup_processor()
+ *
+ * - Initialise the CPU possible map early - this describes the CPUs
+ *   which may be present or become present in the system.
+ * - Call early smp init hook. This can initialize a specific multi-core
+ *   IP which is say common to several platforms (hence not part of
+ *   platform specific int_early() hook)
  */
 void __init smp_init_cpus(void)
 {
@@ -51,6 +56,9 @@ void __init smp_init_cpus(void)
 
 	for (i = 0; i < NR_CPUS; i++)
 		set_cpu_possible(i, true);
+
+	if (plat_smp_ops.init_early_smp)
+		plat_smp_ops.init_early_smp();
 }
 
 /* called from init ( ) =>  process 1 */