Commit 88b3aac6 authored by Helge Deller's avatar Helge Deller
Browse files

parisc: Implement __cpu_die() and __cpu_disable() for CPU hotplugging 



Add relevant code to __cpu_die() and __cpu_disable() to finally enable
the CPU hotplugging features. Reset the irq count values in smp_callin()
to zero before bringing up the CPU.

It seems that the firmware may need up to 8 seconds to fully stop a CPU
in which no other PDC calls are allowed to be made. Use a timeout
__cpu_die() to accommodate for this.

Use "chcpu -d 1" to bring CPU1 down, and "chcpu -e 1" to bring it up.

Signed-off-by: default avatarHelge Deller <deller@gmx.de>
parent db2b0d76

arch/parisc/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -56,6 +56,7 @@ config PARISC 
	select HAVE_ARCH_TRACEHOOK

	select HAVE_REGS_AND_STACK_ACCESS_API

	select GENERIC_SCHED_CLOCK

	select GENERIC_IRQ_MIGRATION if SMP

	select HAVE_UNSTABLE_SCHED_CLOCK if SMP

	select LEGACY_TIMER_TICK

	select CPU_NO_EFFICIENT_FFS

arch/parisc/include/asm/smp.h

+2 −7
Original line number Diff line number Diff line
@@ -44,12 +44,7 @@ static inline void smp_send_all_nop(void) { return; } 


#define NO_PROC_ID		0xFF		/* No processor magic marker */

#define ANY_PROC_ID		0xFF		/* Any processor magic marker */

static inline int __cpu_disable (void) {

  return 0;

}

static inline void __cpu_die (unsigned int cpu) {

  while(1)

    ;

}

int __cpu_disable(void);

void __cpu_die(unsigned int cpu);



#endif /*  __ASM_SMP_H */

arch/parisc/kernel/smp.c

+87 −15
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ 
#include <linux/ftrace.h>

#include <linux/cpu.h>

#include <linux/kgdb.h>

#include <linux/sched/hotplug.h>



#include <linux/atomic.h>

#include <asm/current.h>
@@ -60,8 +61,6 @@ volatile struct task_struct *smp_init_current_idle_task; 
/* track which CPU is booting */

static volatile int cpu_now_booting;



static int parisc_max_cpus = 1;



static DEFINE_PER_CPU(spinlock_t, ipi_lock);



enum ipi_message_type {
@@ -269,7 +268,7 @@ void arch_send_call_function_single_ipi(int cpu) 
/*

 * Called by secondaries to update state and initialize CPU registers.

 */

static void __init

static void

smp_cpu_init(int cpunum)

{

	extern void init_IRQ(void);    /* arch/parisc/kernel/irq.c */
@@ -309,7 +308,7 @@ smp_cpu_init(int cpunum) 
 * Slaves start using C here. Indirectly called from smp_slave_stext.

 * Do what start_kernel() and main() do for boot strap processor (aka monarch)

 */

void __init smp_callin(unsigned long pdce_proc)

void smp_callin(unsigned long pdce_proc)

{

	int slave_id = cpu_now_booting;
@@ -334,11 +333,28 @@ void __init smp_callin(unsigned long pdce_proc) 
/*

 * Bring one cpu online.

 */

int smp_boot_one_cpu(int cpuid, struct task_struct *idle)

static int smp_boot_one_cpu(int cpuid, struct task_struct *idle)

{

	const struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpuid);

	long timeout;



#ifdef CONFIG_HOTPLUG_CPU

	int i;



	/* reset irq statistics for this CPU */

	memset(&per_cpu(irq_stat, cpuid), 0, sizeof(irq_cpustat_t));

	for (i = 0; i < NR_IRQS; i++) {

		struct irq_desc *desc = irq_to_desc(i);



		if (desc && desc->kstat_irqs)

			*per_cpu_ptr(desc->kstat_irqs, cpuid) = 0;

	}

#endif



	/* wait until last booting CPU has started. */

	while (cpu_now_booting)

		;



	/* Let _start know what logical CPU we're booting

	** (offset into init_tasks[],cpu_data[])

	*/
@@ -374,7 +390,6 @@ int smp_boot_one_cpu(int cpuid, struct task_struct *idle) 
		if(cpu_online(cpuid)) {

			/* Which implies Slave has started up */

			cpu_now_booting = 0;

			smp_init_current_idle_task = NULL;

			goto alive ;

		}

		udelay(100);
@@ -415,25 +430,82 @@ void __init smp_prepare_cpus(unsigned int max_cpus) 
		spin_lock_init(&per_cpu(ipi_lock, cpu));



	init_cpu_present(cpumask_of(0));



	parisc_max_cpus = max_cpus;

	if (!max_cpus)

		printk(KERN_INFO "SMP mode deactivated.\n");

}





void smp_cpus_done(unsigned int cpu_max)

void __init smp_cpus_done(unsigned int cpu_max)

{

	return;

}





int __cpu_up(unsigned int cpu, struct task_struct *tidle)

{

	if (cpu != 0 && cpu < parisc_max_cpus && smp_boot_one_cpu(cpu, tidle))

		return -ENOSYS;

	if (cpu_online(cpu))

		return 0;



	if (num_online_cpus() < setup_max_cpus && smp_boot_one_cpu(cpu, tidle))

		return -EIO;



	return cpu_online(cpu) ? 0 : -EIO;

}



/*

 * __cpu_disable runs on the processor to be shutdown.

 */

int __cpu_disable(void)

{

#ifdef CONFIG_HOTPLUG_CPU

	unsigned int cpu = smp_processor_id();



	remove_cpu_topology(cpu);



	/*

	 * Take this CPU offline.  Once we clear this, we can't return,

	 * and we must not schedule until we're ready to give up the cpu.

	 */

	set_cpu_online(cpu, false);



	disable_percpu_irq(IPI_IRQ);



	irq_migrate_all_off_this_cpu();



	flush_cache_all_local();

	flush_tlb_all_local(NULL);



	/* disable all irqs, including timer irq */

	local_irq_disable();



	/* wait for next timer irq ... */

	mdelay(1000/HZ+100);



	/* ... and then clear all pending external irqs */

	set_eiem(0);

	mtctl(~0UL, CR_EIRR);

	mfctl(CR_EIRR);

	mtctl(0, CR_EIRR);

#endif

	return 0;

}



/*

 * called on the thread which is asking for a CPU to be shutdown -

 * waits until shutdown has completed, or it is timed out.

 */

void __cpu_die(unsigned int cpu)

{

	pdc_cpu_rendezvous_lock();



	if (!cpu_wait_death(cpu, 5)) {

		pr_crit("CPU%u: cpu didn't die\n", cpu);

		return;

	}

	pr_info("CPU%u: is shutting down\n", cpu);



	/* set task's state to interruptible sleep */

	set_current_state(TASK_INTERRUPTIBLE);

	schedule_timeout((IS_ENABLED(CONFIG_64BIT) ? 8:2) * HZ);



	return cpu_online(cpu) ? 0 : -ENOSYS;

	pdc_cpu_rendezvous_unlock();

}



#ifdef CONFIG_PROC_FS