ARC: smp: Move default boot kick/wait code out of MCIP into common code

For non halt-on-reset case, all cores start of simultaneously in @stext.
Master core0 proceeds with kernel boot, while other spin-wait on
@wake_flag being set by master once it is ready. So NO hardware assist
is needed for master to "kick" the others.

This patch moves this soft implementation out of mcip.c (as there is no
hardware assist) into common smp.c

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

1 files changed, 21 insertions, 25 deletions

diff --git a/arch/arc/kernel/smp.c b/arch/arc/kernel/smp.c
index be13d12420ba..f6175fc5f2bb 100644
--- a/arch/arc/kernel/smp.c
+++ b/arch/arc/kernel/smp.c
@@ -72,35 +72,29 @@ void __init smp_cpus_done(unsigned int max_cpus)
 }
 
 /*
- * After power-up, a non Master CPU needs to wait for Master to kick start it
- *
- * The default implementation halts
- *
- * This relies on platform specific support allowing Master to directly set
- * this CPU's PC (to be @first_lines_of_secondary() and kick start it.
- *
- * In lack of such h/w assist, platforms can override this function
- *   - make this function busy-spin on a token, eventually set by Master
- *     (from arc_platform_smp_wakeup_cpu())
- *   - Once token is available, jump to @first_lines_of_secondary
- *     (using inline asm).
- *
- * Alert: can NOT use stack here as it has not been determined/setup for CPU.
- *        If it turns out to be elaborate, it's better to code it in assembly
- *
+ * Default smp boot helper for Run-on-reset case where all cores start off
+ * together. Non-masters need to wait for Master to start running.
+ * This is implemented using a flag in memory, which Non-masters spin-wait on.
+ * Master sets it to cpu-id of core to "ungate" it.
  */
-void __weak arc_platform_smp_wait_to_boot(int cpu)
+static volatile int wake_flag;
+
+static void arc_default_smp_cpu_kick(int cpu, unsigned long pc)
 {
-	/*
-	 * As a hack for debugging - since debugger will single-step over the
-	 * FLAG insn - wrap the halt itself it in a self loop
-	 */
-	__asm__ __volatile__(
-	"1:		\n"
-	"	flag 1	\n"
-	"	b 1b	\n");
+	BUG_ON(cpu == 0);
+	wake_flag = cpu;
+}
+
+void arc_platform_smp_wait_to_boot(int cpu)
+{
+	while (wake_flag != cpu)
+		;
+
+	wake_flag = 0;
+	__asm__ __volatile__("j @first_lines_of_secondary	\n");
 }
 
+
 const char *arc_platform_smp_cpuinfo(void)
 {
 	return plat_smp_ops.info ? : "";
@@ -161,6 +155,8 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
 	if (plat_smp_ops.cpu_kick)
 		plat_smp_ops.cpu_kick(cpu,
 				(unsigned long)first_lines_of_secondary);
+	else
+		arc_default_smp_cpu_kick(cpu, (unsigned long)NULL);
 
 	/* wait for 1 sec after kicking the secondary */
 	wait_till = jiffies + HZ;