[PATCH 1/2] csky: Enable generic clockevent broadcast

[guoren at kernel.org]

From: Guo Ren <guoren at linux.alibaba.com>

When percpu-timers are stopped by deep power saving mode, we need
system timer help to broadcast IPI_TIMER.

This is first introduced by broken x86 hardware, where the local apic
timer stops in C3 state. But many other architectures(powerpc, mips,
arm, hexagon, openrisc, sh) have supported the infrastructure to
deal with Power Management issues.

Signed-off-by: Guo Ren <guoren at linux.alibaba.com>
Cc: Arnd Bergmann <arnd at arndb.de>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: Daniel Lezcano <daniel.lezcano at linaro.org>
---
 arch/csky/Kconfig      |  2 ++
 arch/csky/kernel/smp.c | 17 +++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
index 34e91224adc3..4328511ac050 100644
--- a/arch/csky/Kconfig
+++ b/arch/csky/Kconfig
@@ -6,6 +6,7 @@ config CSKY
 	select ARCH_HAS_GCOV_PROFILE_ALL
 	select ARCH_HAS_SYNC_DMA_FOR_CPU
 	select ARCH_HAS_SYNC_DMA_FOR_DEVICE
+	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
 	select ARCH_USE_BUILTIN_BSWAP
 	select ARCH_USE_QUEUED_RWLOCKS
 	select ARCH_WANT_FRAME_POINTERS if !CPU_CK610
@@ -19,6 +20,7 @@ config CSKY
 	select IRQ_DOMAIN
 	select HANDLE_DOMAIN_IRQ
 	select DW_APB_TIMER_OF
+	select GENERIC_CLOCKEVENTS_BROADCAST if SMP
 	select GENERIC_IOREMAP
 	select GENERIC_LIB_ASHLDI3
 	select GENERIC_LIB_ASHRDI3
diff --git a/arch/csky/kernel/smp.c b/arch/csky/kernel/smp.c
index 0f9f5eef9338..76d38d84da70 100644
--- a/arch/csky/kernel/smp.c
+++ b/arch/csky/kernel/smp.c
@@ -8,6 +8,7 @@
 #include <linux/kernel_stat.h>
 #include <linux/notifier.h>
 #include <linux/cpu.h>
+#include <linux/clockchips.h>
 #include <linux/percpu.h>
 #include <linux/delay.h>
 #include <linux/err.h>
@@ -32,6 +33,7 @@ enum ipi_message_type {
 	IPI_RESCHEDULE,
 	IPI_CALL_FUNC,
 	IPI_IRQ_WORK,
+	IPI_TIMER,
 	IPI_MAX
 };
 
@@ -67,6 +69,13 @@ static irqreturn_t handle_ipi(int irq, void *dev)
 			irq_work_run();
 		}
 
+#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
+		if (ops & (1 << IPI_TIMER)) {
+			stats[IPI_TIMER]++;
+			tick_receive_broadcast();
+		}
+#endif
+
 		BUG_ON((ops >> IPI_MAX) != 0);
 	}
 
@@ -102,6 +111,7 @@ static const char * const ipi_names[] = {
 	[IPI_RESCHEDULE]	= "Rescheduling interrupts",
 	[IPI_CALL_FUNC]		= "Function call interrupts",
 	[IPI_IRQ_WORK]		= "Irq work interrupts",
+	[IPI_TIMER]		= "Timer broadcast interrupts",
 };
 
 int arch_show_interrupts(struct seq_file *p, int prec)
@@ -130,6 +140,13 @@ void arch_send_call_function_single_ipi(int cpu)
 	send_ipi_message(cpumask_of(cpu), IPI_CALL_FUNC);
 }
 
+#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
+void tick_broadcast(const struct cpumask *mask)
+{
+	send_ipi_message(mask, IPI_TIMER);
+}
+#endif
+
 static void ipi_stop(void *unused)
 {
 	while (1);
-- 
2.25.1