ARM / mach-shmobile: r8a7779 SMP TWD boot regression fix

Fix SMP TWD boot regression on r8a7779 based platforms caused by:

4200b16d ARM: shmobile: convert to twd_local_timer_register() interface

After the merge of the above commit it has been impossible to boot
r8a7779 based SoCs with SMP enabled and CONFIG_HAVE_ARM_TWD=y. The
kernel crashes at smp_init_cpus() timing which is before the console
has been initialized, so to the user this looks like a kernel lock up
without any particular error message.

This patch fixes the regression on r8a7779 by moving the TWD
registration code from smp_init_cpus() to sys_timer->init() time.
Signed-off-by: Magnus Damm <damm@opensource.se>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

arch/arm/mach-shmobile/include/mach/common.h

@@ -82,5 +82,6 @@ extern int r8a7779_platform_cpu_kill(unsigned int cpu);
 extern void r8a7779_secondary_init(unsigned int cpu);
 extern int r8a7779_boot_secondary(unsigned int cpu);
 extern void r8a7779_smp_prepare_cpus(void);
+extern void r8a7779_register_twd(void);
 
 #endif /* __ARCH_MACH_COMMON_H */

arch/arm/mach-shmobile/setup-r8a7779.c

@@ -262,10 +262,14 @@ void __init r8a7779_add_standard_devices(void)
 			    ARRAY_SIZE(r8a7779_late_devices));
 }
 
+/* do nothing for !CONFIG_SMP or !CONFIG_HAVE_TWD */
+void __init __weak r8a7779_register_twd(void) { }
+
 static void __init r8a7779_earlytimer_init(void)
 {
 	r8a7779_clock_init();
 	shmobile_earlytimer_init();
+	r8a7779_register_twd();
 }
 
 void __init r8a7779_add_early_devices(void)

arch/arm/mach-shmobile/smp-r8a7779.c

@@ -64,8 +64,15 @@ static void __iomem *scu_base_addr(void)
 static DEFINE_SPINLOCK(scu_lock);
 static unsigned long tmp;
 
+#ifdef CONFIG_HAVE_ARM_TWD
 static DEFINE_TWD_LOCAL_TIMER(twd_local_timer, 0xf0000600, 29);
 
+void __init r8a7779_register_twd(void)
+{
+	twd_local_timer_register(&twd_local_timer);
+}
+#endif
+
 static void modify_scu_cpu_psr(unsigned long set, unsigned long clr)
 {
 	void __iomem *scu_base = scu_base_addr();
@@ -84,7 +91,6 @@ unsigned int __init r8a7779_get_core_count(void)
 {
 	void __iomem *scu_base = scu_base_addr();
 
-	shmobile_twd_init(&twd_local_timer);
 	return scu_get_core_count(scu_base);
 }