Commit 1f85008e authored by Lorenzo Pieralisi's avatar Lorenzo Pieralisi
Browse files

arm64: enable generic clockevent broadcast 



On platforms with power management capabilities, timers that are shut
down when a CPU enters deep C-states must be emulated using an always-on
timer and a timer IPI to relay the timer IRQ to target CPUs on an SMP
system.

This patch enables the generic clockevents broadcast infrastructure for
arm64, by providing the required Kconfig entries and adding the timer
IPI infrastructure.

Acked-by: default avatarDaniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: default avatarLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
parent 60fc6942

arch/arm64/Kconfig

+2 −0
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ config ARM64 
	def_bool y

	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE

	select ARCH_USE_CMPXCHG_LOCKREF

	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST

	select ARCH_WANT_OPTIONAL_GPIOLIB

	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION

	select ARCH_WANT_FRAME_POINTERS
@@ -12,6 +13,7 @@ config ARM64 
	select CLONE_BACKWARDS

	select COMMON_CLK

	select GENERIC_CLOCKEVENTS

	select GENERIC_CLOCKEVENTS_BROADCAST if SMP

	select GENERIC_IOMAP

	select GENERIC_IRQ_PROBE

	select GENERIC_IRQ_SHOW

arch/arm64/include/asm/hardirq.h

+1 −1
Original line number Diff line number Diff line
@@ -20,7 +20,7 @@ 
#include <linux/threads.h>

#include <asm/irq.h>



#define NR_IPI	4

#define NR_IPI	5



typedef struct {

	unsigned int __softirq_pending;

arch/arm64/kernel/smp.c

+17 −0
Original line number Diff line number Diff line
@@ -61,6 +61,7 @@ enum ipi_msg_type { 
	IPI_CALL_FUNC,

	IPI_CALL_FUNC_SINGLE,

	IPI_CPU_STOP,

	IPI_TIMER,

};



/*
@@ -447,6 +448,7 @@ static const char *ipi_types[NR_IPI] = { 
	S(IPI_CALL_FUNC, "Function call interrupts"),

	S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),

	S(IPI_CPU_STOP, "CPU stop interrupts"),

	S(IPI_TIMER, "Timer broadcast interrupts"),

};



void show_ipi_list(struct seq_file *p, int prec)
@@ -532,6 +534,14 @@ void handle_IPI(int ipinr, struct pt_regs *regs) 
		irq_exit();

		break;



#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST

	case IPI_TIMER:

		irq_enter();

		tick_receive_broadcast();

		irq_exit();

		break;

#endif



	default:

		pr_crit("CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr);

		break;
@@ -544,6 +554,13 @@ void smp_send_reschedule(int cpu) 
	smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);

}



#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST

void tick_broadcast(const struct cpumask *mask)

{

	smp_cross_call(mask, IPI_TIMER);

}

#endif



void smp_send_stop(void)

{

	unsigned long timeout;

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