Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit d1669912 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

idle: Implement generic idle function 



All idle functions in arch/* are more or less the same, plus minus a
few bugs and extra instrumentation, tickless support and other
optional items.

Implement a generic idle function which resembles the functionality
found in arch/. Provide weak arch_cpu_idle_* functions which can be
overridden by the architecture code if needed.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: default avatarCc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130321215233.646635455@linutronix.de


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent a1a04ec3

arch/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -216,6 +216,9 @@ config USE_GENERIC_SMP_HELPERS 
config GENERIC_SMP_IDLE_THREAD

       bool



config GENERIC_IDLE_LOOP

       bool



# Select if arch init_task initializer is different to init/init_task.c

config ARCH_INIT_TASK

       bool

include/linux/cpu.h

+8 −0
Original line number Diff line number Diff line
@@ -220,4 +220,12 @@ enum cpuhp_state { 
void cpu_startup_entry(enum cpuhp_state state);

void cpu_idle(void);



void cpu_idle_poll_ctrl(bool enable);



void arch_cpu_idle(void);

void arch_cpu_idle_prepare(void);

void arch_cpu_idle_enter(void);

void arch_cpu_idle_exit(void);

void arch_cpu_idle_dead(void);



#endif /* _LINUX_CPU_H_ */

kernel/cpu/idle.c

+105 −0
Original line number Diff line number Diff line
@@ -3,8 +3,113 @@ 
 */

#include <linux/sched.h>

#include <linux/cpu.h>

#include <linux/tick.h>

#include <linux/mm.h>



#include <asm/tlb.h>



#include <trace/events/power.h>



#ifndef CONFIG_GENERIC_IDLE_LOOP

void cpu_startup_entry(enum cpuhp_state state)

{

	cpu_idle();

}

#else



static int __read_mostly cpu_idle_force_poll;



void cpu_idle_poll_ctrl(bool enable)

{

	if (enable) {

		cpu_idle_force_poll++;

	} else {

		cpu_idle_force_poll--;

		WARN_ON_ONCE(cpu_idle_force_poll < 0);

	}

}



#ifdef CONFIG_GENERIC_IDLE_POLL_SETUP

static int __init cpu_idle_poll_setup(char *__unused)

{

	cpu_idle_force_poll = 1;

	return 1;

}

__setup("nohlt", cpu_idle_poll_setup);



static int __init cpu_idle_nopoll_setup(char *__unused)

{

	cpu_idle_force_poll = 0;

	return 1;

}

__setup("hlt", cpu_idle_nopoll_setup);

#endif



static inline int cpu_idle_poll(void)

{

	trace_cpu_idle_rcuidle(0, smp_processor_id());

	local_irq_enable();

	while (!need_resched())

		cpu_relax();

	trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());

	return 1;

}



/* Weak implementations for optional arch specific functions */

void __weak arch_cpu_idle_prepare(void) { }

void __weak arch_cpu_idle_enter(void) { }

void __weak arch_cpu_idle_exit(void) { }

void __weak arch_cpu_idle_dead(void) { }

void __weak arch_cpu_idle(void)

{

	cpu_idle_force_poll = 1;

}



/*

 * Generic idle loop implementation

 */

static void cpu_idle_loop(void)

{

	while (1) {

		tick_nohz_idle_enter();



		while (!need_resched()) {

			check_pgt_cache();

			rmb();



			if (cpu_is_offline(smp_processor_id()))

				arch_cpu_idle_dead();



			local_irq_disable();

			arch_cpu_idle_enter();



			if (cpu_idle_force_poll) {

				cpu_idle_poll();

			} else {

				current_clr_polling();

				if (!need_resched()) {

					stop_critical_timings();

					rcu_idle_enter();

					arch_cpu_idle();

					WARN_ON_ONCE(irqs_disabled());

					rcu_idle_exit();

					start_critical_timings();

				} else {

					local_irq_enable();

				}

				current_set_polling();

			}

			arch_cpu_idle_exit();

		}

		tick_nohz_idle_exit();

		schedule_preempt_disabled();

	}

}



void cpu_startup_entry(enum cpuhp_state state)

{

	current_set_polling();

	arch_cpu_idle_prepare();

	cpu_idle_loop();

}

#endif