riscv: Enable generic clockevent broadcast

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@linux.alibaba.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
index ea028d9e0d24..8325d33411d8 100644
--- a/arch/riscv/kernel/smp.c
+++ b/arch/riscv/kernel/smp.c
@@ -9,6 +9,7 @@
  */
 
 #include <linux/cpu.h>
+#include <linux/clockchips.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/profile.h>
@@ -27,6 +28,7 @@ enum ipi_message_type {
 	IPI_CALL_FUNC,
 	IPI_CPU_STOP,
 	IPI_IRQ_WORK,
+	IPI_TIMER,
 	IPI_MAX
 };
 
@@ -176,6 +178,12 @@ void handle_IPI(struct pt_regs *regs)
 			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);
 
 		/* Order data access and bit testing. */
@@ -192,6 +200,7 @@ static const char * const ipi_names[] = {
 	[IPI_CALL_FUNC]		= "Function call interrupts",
 	[IPI_CPU_STOP]		= "CPU stop interrupts",
 	[IPI_IRQ_WORK]		= "IRQ work interrupts",
+	[IPI_TIMER]		= "Timer broadcast interrupts",
 };
 
 void show_ipi_stats(struct seq_file *p, int prec)
@@ -217,6 +226,13 @@ void arch_send_call_function_single_ipi(int cpu)
 	send_ipi_single(cpu, IPI_CALL_FUNC);
 }
 
+#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
+void tick_broadcast(const struct cpumask *mask)
+{
+	send_ipi_mask(mask, IPI_TIMER);
+}
+#endif
+
 void smp_send_stop(void)
 {
 	unsigned long timeout;