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Commit 1b2bc75c authored by Ralf Baechle's avatar Ralf Baechle
Browse files

MIPS: Add arch generic CPU hotplug 



Each platform has to add support for CPU hotplugging itself by providing
suitable definitions for the cpu_disable and cpu_die of the smp_ops
methods and setting SYS_SUPPORTS_HOTPLUG_CPU.  A platform should only set
SYS_SUPPORTS_HOTPLUG_CPU once all it's smp_ops definitions have the
necessary changes.  This patch contains the changes to the dummy smp_ops
definition for uni-processor systems.

Parts of the code contributed by Cavium Inc.

Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 4ac4aa5c

arch/mips/Kconfig

+10 −1
Original line number Diff line number Diff line
@@ -784,8 +784,17 @@ config SYS_HAS_EARLY_PRINTK 
	bool



config HOTPLUG_CPU

	bool "Support for hot-pluggable CPUs"

	depends on SMP && HOTPLUG && SYS_SUPPORTS_HOTPLUG_CPU

	help

	  Say Y here to allow turning CPUs off and on. CPUs can be

	  controlled through /sys/devices/system/cpu.

	  (Note: power management support will enable this option

	    automatically on SMP systems. )

	  Say N if you want to disable CPU hotplug.



config SYS_SUPPORTS_HOTPLUG_CPU

	bool

	default n



config I8259

	bool

arch/mips/include/asm/smp-ops.h

+4 −0
Original line number Diff line number Diff line
@@ -26,6 +26,10 @@ struct plat_smp_ops { 
	void (*boot_secondary)(int cpu, struct task_struct *idle);

	void (*smp_setup)(void);

	void (*prepare_cpus)(unsigned int max_cpus);

#ifdef CONFIG_HOTPLUG_CPU

	int (*cpu_disable)(void);

	void (*cpu_die)(unsigned int cpu);

#endif

};



extern void register_smp_ops(struct plat_smp_ops *ops);

arch/mips/include/asm/smp.h

+19 −0
Original line number Diff line number Diff line
@@ -41,6 +41,7 @@ extern int __cpu_logical_map[NR_CPUS]; 
/* Octeon - Tell another core to flush its icache */

#define SMP_ICACHE_FLUSH	0x4



extern cpumask_t cpu_callin_map;



extern void asmlinkage smp_bootstrap(void);
@@ -56,6 +57,24 @@ static inline void smp_send_reschedule(int cpu) 
	mp_ops->send_ipi_single(cpu, SMP_RESCHEDULE_YOURSELF);

}



#ifdef CONFIG_HOTPLUG_CPU

static inline int __cpu_disable(void)

{

	extern struct plat_smp_ops *mp_ops;     /* private */



	return mp_ops->cpu_disable();

}



static inline void __cpu_die(unsigned int cpu)

{

	extern struct plat_smp_ops *mp_ops;     /* private */



	mp_ops->cpu_die(cpu);

}



extern void play_dead(void);

#endif



extern asmlinkage void smp_call_function_interrupt(void);



extern void arch_send_call_function_single_ipi(int cpu);

arch/mips/kernel/process.c

+12 −1
Original line number Diff line number Diff line
@@ -50,10 +50,15 @@ 
 */

void __noreturn cpu_idle(void)

{

	int cpu;



	/* CPU is going idle. */

	cpu = smp_processor_id();



	/* endless idle loop with no priority at all */

	while (1) {

		tick_nohz_stop_sched_tick(1);

		while (!need_resched()) {

		while (!need_resched() && cpu_online(cpu)) {

#ifdef CONFIG_MIPS_MT_SMTC

			extern void smtc_idle_loop_hook(void);
@@ -62,6 +67,12 @@ void __noreturn cpu_idle(void) 
			if (cpu_wait)

				(*cpu_wait)();

		}

#ifdef CONFIG_HOTPLUG_CPU

		if (!cpu_online(cpu) && !cpu_isset(cpu, cpu_callin_map) &&

		    (system_state == SYSTEM_RUNNING ||

		     system_state == SYSTEM_BOOTING))

			play_dead();

#endif

		tick_nohz_restart_sched_tick();

		preempt_enable_no_resched();

		schedule();

arch/mips/kernel/smp-up.c

+16 −0
Original line number Diff line number Diff line
@@ -55,6 +55,18 @@ static void __init up_prepare_cpus(unsigned int max_cpus) 
{

}



#ifdef CONFIG_HOTPLUG_CPU

static int up_cpu_disable(void)

{

	return -ENOSYS;

}



static void up_cpu_die(unsigned int cpu)

{

	BUG();

}

#endif



struct plat_smp_ops up_smp_ops = {

	.send_ipi_single	= up_send_ipi_single,

	.send_ipi_mask		= up_send_ipi_mask,
@@ -64,4 +76,8 @@ struct plat_smp_ops up_smp_ops = { 
	.boot_secondary		= up_boot_secondary,

	.smp_setup		= up_smp_setup,

	.prepare_cpus		= up_prepare_cpus,

#ifdef CONFIG_HOTPLUG_CPU

	.cpu_disable		= up_cpu_disable,

	.cpu_die		= up_cpu_die,

#endif

};