[linux-2.6-block.git] / arch / parisc / kernel / smp.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
** SMP Support
**
** Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
** Copyright (C) 1999 David Mosberger-Tang <davidm@hpl.hp.com>
** Copyright (C) 2001,2004 Grant Grundler <grundler@parisc-linux.org>
** 
** Lots of stuff stolen from arch/alpha/kernel/smp.c
** ...and then parisc stole from arch/ia64/kernel/smp.c. Thanks David! :^)
**
** Thanks to John Curry and Ullas Ponnadi. I learned a lot from their work.
** -grant (1/12/2001)
**
*/
#include <linux/types.h>
#include <linux/spinlock.h>

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched/mm.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/smp.h>
#include <linux/kernel_stat.h>
#include <linux/mm.h>
#include <linux/err.h>
#include <linux/delay.h>
#include <linux/bitops.h>
#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>
#include <asm/delay.h>
#include <asm/tlbflush.h>

#include <asm/io.h>
#include <asm/irq.h>		/* for CPU_IRQ_REGION and friends */
#include <asm/mmu_context.h>
#include <asm/page.h>
#include <asm/processor.h>
#include <asm/ptrace.h>
#include <asm/unistd.h>
#include <asm/cacheflush.h>

#undef DEBUG_SMP
#ifdef DEBUG_SMP
static int smp_debug_lvl = 0;
#define smp_debug(lvl, printargs...)		\
		if (lvl >= smp_debug_lvl)	\
			printk(printargs);
#else
#define smp_debug(lvl, ...)	do { } while(0)
#endif /* DEBUG_SMP */

volatile struct task_struct *smp_init_current_idle_task;

/* track which CPU is booting */
static volatile int cpu_now_booting;

static DEFINE_PER_CPU(spinlock_t, ipi_lock);

enum ipi_message_type {
	IPI_NOP=0,
	IPI_RESCHEDULE=1,
	IPI_CALL_FUNC,
	IPI_CPU_START,
	IPI_CPU_STOP,
	IPI_CPU_TEST,
#ifdef CONFIG_KGDB
	IPI_ENTER_KGDB,
#endif
};


/********** SMP inter processor interrupt and communication routines */

#undef PER_CPU_IRQ_REGION
#ifdef PER_CPU_IRQ_REGION
/* XXX REVISIT Ignore for now.
**    *May* need this "hook" to register IPI handler
**    once we have perCPU ExtIntr switch tables.
*/
static void
ipi_init(int cpuid)
{
#error verify IRQ_OFFSET(IPI_IRQ) is ipi_interrupt() in new IRQ region

	if(cpu_online(cpuid) )
	{
		switch_to_idle_task(current);
	}

	return;
}
#endif


/*
** Yoink this CPU from the runnable list... 
**
*/
static void
halt_processor(void) 
{
	/* REVISIT : redirect I/O Interrupts to another CPU? */
	/* REVISIT : does PM *know* this CPU isn't available? */
	set_cpu_online(smp_processor_id(), false);
	local_irq_disable();
	__pdc_cpu_rendezvous();
	for (;;)
		;
}


irqreturn_t __irq_entry
ipi_interrupt(int irq, void *dev_id) 
{
	int this_cpu = smp_processor_id();
	struct cpuinfo_parisc *p = &per_cpu(cpu_data, this_cpu);
	unsigned long ops;
	unsigned long flags;

	for (;;) {
		spinlock_t *lock = &per_cpu(ipi_lock, this_cpu);
		spin_lock_irqsave(lock, flags);
		ops = p->pending_ipi;
		p->pending_ipi = 0;
		spin_unlock_irqrestore(lock, flags);

		mb(); /* Order bit clearing and data access. */

		if (!ops)
		    break;

		while (ops) {
			unsigned long which = ffz(~ops);

			ops &= ~(1 << which);

			switch (which) {
			case IPI_NOP:
				smp_debug(100, KERN_DEBUG "CPU%d IPI_NOP\n", this_cpu);
				break;
				
			case IPI_RESCHEDULE:
				smp_debug(100, KERN_DEBUG "CPU%d IPI_RESCHEDULE\n", this_cpu);
				inc_irq_stat(irq_resched_count);
				scheduler_ipi();
				break;

			case IPI_CALL_FUNC:
				smp_debug(100, KERN_DEBUG "CPU%d IPI_CALL_FUNC\n", this_cpu);
				inc_irq_stat(irq_call_count);
				generic_smp_call_function_interrupt();
				break;

			case IPI_CPU_START:
				smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_START\n", this_cpu);
				break;

			case IPI_CPU_STOP:
				smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_STOP\n", this_cpu);
				halt_processor();
				break;

			case IPI_CPU_TEST:
				smp_debug(100, KERN_DEBUG "CPU%d is alive!\n", this_cpu);
				break;
#ifdef CONFIG_KGDB
			case IPI_ENTER_KGDB:
				smp_debug(100, KERN_DEBUG "CPU%d ENTER_KGDB\n", this_cpu);
				kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
				break;
#endif
			default:
				printk(KERN_CRIT "Unknown IPI num on CPU%d: %lu\n",
					this_cpu, which);
				return IRQ_NONE;
			} /* Switch */

			/* before doing more, let in any pending interrupts */
			if (ops) {
				local_irq_enable();
				local_irq_disable();
			}
		} /* while (ops) */
	}
	return IRQ_HANDLED;
}


static inline void
ipi_send(int cpu, enum ipi_message_type op)
{
	struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpu);
	spinlock_t *lock = &per_cpu(ipi_lock, cpu);
	unsigned long flags;

	spin_lock_irqsave(lock, flags);
	p->pending_ipi |= 1 << op;
	gsc_writel(IPI_IRQ - CPU_IRQ_BASE, p->hpa);
	spin_unlock_irqrestore(lock, flags);
}

static void
send_IPI_mask(const struct cpumask *mask, enum ipi_message_type op)
{
	int cpu;

	for_each_cpu(cpu, mask)
		ipi_send(cpu, op);
}

static inline void
send_IPI_single(int dest_cpu, enum ipi_message_type op)
{
	BUG_ON(dest_cpu == NO_PROC_ID);

	ipi_send(dest_cpu, op);
}

static inline void
send_IPI_allbutself(enum ipi_message_type op)
{
	int i;

	preempt_disable();
	for_each_online_cpu(i) {
		if (i != smp_processor_id())
			send_IPI_single(i, op);
	}
	preempt_enable();
}

#ifdef CONFIG_KGDB
void kgdb_roundup_cpus(void)
{
	send_IPI_allbutself(IPI_ENTER_KGDB);
}
#endif

inline void 
smp_send_stop(void)	{ send_IPI_allbutself(IPI_CPU_STOP); }

void
arch_smp_send_reschedule(int cpu) { send_IPI_single(cpu, IPI_RESCHEDULE); }

void
smp_send_all_nop(void)
{
	send_IPI_allbutself(IPI_NOP);
}

void arch_send_call_function_ipi_mask(const struct cpumask *mask)
{
	send_IPI_mask(mask, IPI_CALL_FUNC);
}

void arch_send_call_function_single_ipi(int cpu)
{
	send_IPI_single(cpu, IPI_CALL_FUNC);
}

/*
 * Called by secondaries to update state and initialize CPU registers.
 */
static void
smp_cpu_init(int cpunum)
{
	/* Set modes and Enable floating point coprocessor */
	init_per_cpu(cpunum);

	disable_sr_hashing();

	mb();

	/* Well, support 2.4 linux scheme as well. */
	if (cpu_online(cpunum))	{
		extern void machine_halt(void); /* arch/parisc.../process.c */

		printk(KERN_CRIT "CPU#%d already initialized!\n", cpunum);
		machine_halt();
	}

	notify_cpu_starting(cpunum);

	set_cpu_online(cpunum, true);

	/* Initialise the idle task for this CPU */
	mmgrab(&init_mm);
	current->active_mm = &init_mm;
	BUG_ON(current->mm);
	enter_lazy_tlb(&init_mm, current);

	init_IRQ();   /* make sure no IRQs are enabled or pending */
	parisc_clockevent_init();
}


/*
 * 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 smp_callin(unsigned long pdce_proc)
{
	int slave_id = cpu_now_booting;

#ifdef CONFIG_64BIT
	WARN_ON(((unsigned long)(PAGE0->mem_pdc_hi) << 32
			| PAGE0->mem_pdc) != pdce_proc);
#endif

	smp_cpu_init(slave_id);

	flush_cache_all_local(); /* start with known state */
	flush_tlb_all_local(NULL);

	local_irq_enable();  /* Interrupts have been off until now */

	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);

	/* NOTREACHED */
	panic("smp_callin() AAAAaaaaahhhh....\n");
}

/*
 * Bring one cpu online.
 */
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) = (struct irqstat) { };
	}
#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[])
	*/
	cpu_now_booting = cpuid;

	/* 
	** boot strap code needs to know the task address since
	** it also contains the process stack.
	*/
	smp_init_current_idle_task = idle ;
	mb();

	printk(KERN_INFO "Releasing cpu %d now, hpa=%lx\n", cpuid, p->hpa);

	/*
	** This gets PDC to release the CPU from a very tight loop.
	**
	** From the PA-RISC 2.0 Firmware Architecture Reference Specification:
	** "The MEM_RENDEZ vector specifies the location of OS_RENDEZ which 
	** is executed after receiving the rendezvous signal (an interrupt to 
	** EIR{0}). MEM_RENDEZ is valid only when it is nonzero and the 
	** contents of memory are valid."
	*/
	gsc_writel(TIMER_IRQ - CPU_IRQ_BASE, p->hpa);
	mb();

	/* 
	 * OK, wait a bit for that CPU to finish staggering about. 
	 * Slave will set a bit when it reaches smp_cpu_init().
	 * Once the "monarch CPU" sees the bit change, it can move on.
	 */
	for (timeout = 0; timeout < 10000; timeout++) {
		if(cpu_online(cpuid)) {
			/* Which implies Slave has started up */
			cpu_now_booting = 0;
			goto alive ;
		}
		udelay(100);
		barrier();
	}
	printk(KERN_CRIT "SMP: CPU:%d is stuck.\n", cpuid);
	return -1;

alive:
	/* Remember the Slave data */
	smp_debug(100, KERN_DEBUG "SMP: CPU:%d came alive after %ld _us\n",
		cpuid, timeout * 100);
	return 0;
}

void __init smp_prepare_boot_cpu(void)
{
	pr_info("SMP: bootstrap CPU ID is 0\n");
}


/*
** inventory.c:do_inventory() hasn't yet been run and thus we
** don't 'discover' the additional CPUs until later.
*/
void __init smp_prepare_cpus(unsigned int max_cpus)
{
	int cpu;

	for_each_possible_cpu(cpu)
		spin_lock_init(&per_cpu(ipi_lock, cpu));

	init_cpu_present(cpumask_of(0));
}


void __init smp_cpus_done(unsigned int cpu_max)
{
}


int __cpu_up(unsigned int cpu, struct task_struct *tidle)
{
	if (cpu_online(cpu))
		return 0;

	if (num_online_cpus() < nr_cpu_ids &&
		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);

	/* Find a new timesync master */
	if (cpu == time_keeper_id) {
		time_keeper_id = cpumask_first(cpu_online_mask);
		pr_info("CPU %d is now promoted to time-keeper master\n", time_keeper_id);
	}

	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();
}

void arch_cpuhp_cleanup_dead_cpu(unsigned int cpu)
{
	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);

	pdc_cpu_rendezvous_unlock();
}
Commit	Line	Data
	1	// SPDX-License-Identifier: GPL-2.0-or-later
	2	/*
	3	** SMP Support
	4	**
	5	** Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
	6	** Copyright (C) 1999 David Mosberger-Tang <davidm@hpl.hp.com>
	7	** Copyright (C) 2001,2004 Grant Grundler <grundler@parisc-linux.org>
	8	**
	9	** Lots of stuff stolen from arch/alpha/kernel/smp.c
	10	** ...and then parisc stole from arch/ia64/kernel/smp.c. Thanks David! :^)
	11	**
	12	** Thanks to John Curry and Ullas Ponnadi. I learned a lot from their work.
	13	** -grant (1/12/2001)
	14	**
	15	*/
	16	#include <linux/types.h>
	17	#include <linux/spinlock.h>
	18
	19	#include <linux/kernel.h>
	20	#include <linux/module.h>
	21	#include <linux/sched/mm.h>
	22	#include <linux/init.h>
	23	#include <linux/interrupt.h>
	24	#include <linux/smp.h>
	25	#include <linux/kernel_stat.h>
	26	#include <linux/mm.h>
	27	#include <linux/err.h>
	28	#include <linux/delay.h>
	29	#include <linux/bitops.h>
	30	#include <linux/ftrace.h>
	31	#include <linux/cpu.h>
	32	#include <linux/kgdb.h>
	33	#include <linux/sched/hotplug.h>
	34
	35	#include <linux/atomic.h>
	36	#include <asm/current.h>
	37	#include <asm/delay.h>
	38	#include <asm/tlbflush.h>
	39
	40	#include <asm/io.h>
	41	#include <asm/irq.h> /* for CPU_IRQ_REGION and friends */
	42	#include <asm/mmu_context.h>
	43	#include <asm/page.h>
	44	#include <asm/processor.h>
	45	#include <asm/ptrace.h>
	46	#include <asm/unistd.h>
	47	#include <asm/cacheflush.h>
	48
	49	#undef DEBUG_SMP
	50	#ifdef DEBUG_SMP
	51	static int smp_debug_lvl = 0;
	52	#define smp_debug(lvl, printargs...) \
	53	if (lvl >= smp_debug_lvl) \
	54	printk(printargs);
	55	#else
	56	#define smp_debug(lvl, ...) do { } while(0)
	57	#endif /* DEBUG_SMP */
	58
	59	volatile struct task_struct *smp_init_current_idle_task;
	60
	61	/* track which CPU is booting */
	62	static volatile int cpu_now_booting;
	63
	64	static DEFINE_PER_CPU(spinlock_t, ipi_lock);
	65
	66	enum ipi_message_type {
	67	IPI_NOP=0,
	68	IPI_RESCHEDULE=1,
	69	IPI_CALL_FUNC,
	70	IPI_CPU_START,
	71	IPI_CPU_STOP,
	72	IPI_CPU_TEST,
	73	#ifdef CONFIG_KGDB
	74	IPI_ENTER_KGDB,
	75	#endif
	76	};
	77
	78
	79	/********** SMP inter processor interrupt and communication routines */
	80
	81	#undef PER_CPU_IRQ_REGION
	82	#ifdef PER_CPU_IRQ_REGION
	83	/* XXX REVISIT Ignore for now.
	84	** May need this "hook" to register IPI handler
	85	** once we have perCPU ExtIntr switch tables.
	86	*/
	87	static void
	88	ipi_init(int cpuid)
	89	{
	90	#error verify IRQ_OFFSET(IPI_IRQ) is ipi_interrupt() in new IRQ region
	91
	92	if(cpu_online(cpuid) )
	93	{
	94	switch_to_idle_task(current);
	95	}
	96
	97	return;
	98	}
	99	#endif
	100
	101
	102	/*
	103	** Yoink this CPU from the runnable list...
	104	**
	105	*/
	106	static void
	107	halt_processor(void)
	108	{
	109	/* REVISIT : redirect I/O Interrupts to another CPU? */
	110	/* REVISIT : does PM know this CPU isn't available? */
	111	set_cpu_online(smp_processor_id(), false);
	112	local_irq_disable();
	113	__pdc_cpu_rendezvous();
	114	for (;;)
	115	;
	116	}
	117
	118
	119	irqreturn_t __irq_entry
	120	ipi_interrupt(int irq, void *dev_id)
	121	{
	122	int this_cpu = smp_processor_id();
	123	struct cpuinfo_parisc *p = &per_cpu(cpu_data, this_cpu);
	124	unsigned long ops;
	125	unsigned long flags;
	126
	127	for (;;) {
	128	spinlock_t *lock = &per_cpu(ipi_lock, this_cpu);
	129	spin_lock_irqsave(lock, flags);
	130	ops = p->pending_ipi;
	131	p->pending_ipi = 0;
	132	spin_unlock_irqrestore(lock, flags);
	133
	134	mb(); /* Order bit clearing and data access. */
	135
	136	if (!ops)
	137	break;
	138
	139	while (ops) {
	140	unsigned long which = ffz(~ops);
	141
	142	ops &= ~(1 << which);
	143
	144	switch (which) {
	145	case IPI_NOP:
	146	smp_debug(100, KERN_DEBUG "CPU%d IPI_NOP\n", this_cpu);
	147	break;
	148
	149	case IPI_RESCHEDULE:
	150	smp_debug(100, KERN_DEBUG "CPU%d IPI_RESCHEDULE\n", this_cpu);
	151	inc_irq_stat(irq_resched_count);
	152	scheduler_ipi();
	153	break;
	154
	155	case IPI_CALL_FUNC:
	156	smp_debug(100, KERN_DEBUG "CPU%d IPI_CALL_FUNC\n", this_cpu);
	157	inc_irq_stat(irq_call_count);
	158	generic_smp_call_function_interrupt();
	159	break;
	160
	161	case IPI_CPU_START:
	162	smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_START\n", this_cpu);
	163	break;
	164
	165	case IPI_CPU_STOP:
	166	smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_STOP\n", this_cpu);
	167	halt_processor();
	168	break;
	169
	170	case IPI_CPU_TEST:
	171	smp_debug(100, KERN_DEBUG "CPU%d is alive!\n", this_cpu);
	172	break;
	173	#ifdef CONFIG_KGDB
	174	case IPI_ENTER_KGDB:
	175	smp_debug(100, KERN_DEBUG "CPU%d ENTER_KGDB\n", this_cpu);
	176	kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
	177	break;
	178	#endif
	179	default:
	180	printk(KERN_CRIT "Unknown IPI num on CPU%d: %lu\n",
	181	this_cpu, which);
	182	return IRQ_NONE;
	183	} /* Switch */
	184
	185	/* before doing more, let in any pending interrupts */
	186	if (ops) {
	187	local_irq_enable();
	188	local_irq_disable();
	189	}
	190	} /* while (ops) */
	191	}
	192	return IRQ_HANDLED;
	193	}
	194
	195
	196	static inline void
	197	ipi_send(int cpu, enum ipi_message_type op)
	198	{
	199	struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpu);
	200	spinlock_t *lock = &per_cpu(ipi_lock, cpu);
	201	unsigned long flags;
	202
	203	spin_lock_irqsave(lock, flags);
	204	p->pending_ipi \|= 1 << op;
	205	gsc_writel(IPI_IRQ - CPU_IRQ_BASE, p->hpa);
	206	spin_unlock_irqrestore(lock, flags);
	207	}
	208
	209	static void
	210	send_IPI_mask(const struct cpumask *mask, enum ipi_message_type op)
	211	{
	212	int cpu;
	213
	214	for_each_cpu(cpu, mask)
	215	ipi_send(cpu, op);
	216	}
	217
	218	static inline void
	219	send_IPI_single(int dest_cpu, enum ipi_message_type op)
	220	{
	221	BUG_ON(dest_cpu == NO_PROC_ID);
	222
	223	ipi_send(dest_cpu, op);
	224	}
	225
	226	static inline void
	227	send_IPI_allbutself(enum ipi_message_type op)
	228	{
	229	int i;
	230
	231	preempt_disable();
	232	for_each_online_cpu(i) {
	233	if (i != smp_processor_id())
	234	send_IPI_single(i, op);
	235	}
	236	preempt_enable();
	237	}
	238
	239	#ifdef CONFIG_KGDB
	240	void kgdb_roundup_cpus(void)
	241	{
	242	send_IPI_allbutself(IPI_ENTER_KGDB);
	243	}
	244	#endif
	245
	246	inline void
	247	smp_send_stop(void) { send_IPI_allbutself(IPI_CPU_STOP); }
	248
	249	void
	250	arch_smp_send_reschedule(int cpu) { send_IPI_single(cpu, IPI_RESCHEDULE); }
	251
	252	void
	253	smp_send_all_nop(void)
	254	{
	255	send_IPI_allbutself(IPI_NOP);
	256	}
	257
	258	void arch_send_call_function_ipi_mask(const struct cpumask *mask)
	259	{
	260	send_IPI_mask(mask, IPI_CALL_FUNC);
	261	}
	262
	263	void arch_send_call_function_single_ipi(int cpu)
	264	{
	265	send_IPI_single(cpu, IPI_CALL_FUNC);
	266	}
	267
	268	/*
	269	* Called by secondaries to update state and initialize CPU registers.
	270	*/
	271	static void
	272	smp_cpu_init(int cpunum)
	273	{
	274	/* Set modes and Enable floating point coprocessor */
	275	init_per_cpu(cpunum);
	276
	277	disable_sr_hashing();
	278
	279	mb();
	280
	281	/* Well, support 2.4 linux scheme as well. */
	282	if (cpu_online(cpunum)) {
	283	extern void machine_halt(void); /* arch/parisc.../process.c */
	284
	285	printk(KERN_CRIT "CPU#%d already initialized!\n", cpunum);
	286	machine_halt();
	287	}
	288
	289	notify_cpu_starting(cpunum);
	290
	291	set_cpu_online(cpunum, true);
	292
	293	/* Initialise the idle task for this CPU */
	294	mmgrab(&init_mm);
	295	current->active_mm = &init_mm;
	296	BUG_ON(current->mm);
	297	enter_lazy_tlb(&init_mm, current);
	298
	299	init_IRQ(); /* make sure no IRQs are enabled or pending */
	300	parisc_clockevent_init();
	301	}
	302
	303
	304	/*
	305	* Slaves start using C here. Indirectly called from smp_slave_stext.
	306	* Do what start_kernel() and main() do for boot strap processor (aka monarch)
	307	*/
	308	void smp_callin(unsigned long pdce_proc)
	309	{
	310	int slave_id = cpu_now_booting;
	311
	312	#ifdef CONFIG_64BIT
	313	WARN_ON(((unsigned long)(PAGE0->mem_pdc_hi) << 32
	314	\| PAGE0->mem_pdc) != pdce_proc);
	315	#endif
	316
	317	smp_cpu_init(slave_id);
	318
	319	flush_cache_all_local(); /* start with known state */
	320	flush_tlb_all_local(NULL);
	321
	322	local_irq_enable(); /* Interrupts have been off until now */
	323
	324	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
	325
	326	/* NOTREACHED */
	327	panic("smp_callin() AAAAaaaaahhhh....\n");
	328	}
	329
	330	/*
	331	* Bring one cpu online.
	332	*/
	333	static int smp_boot_one_cpu(int cpuid, struct task_struct *idle)
	334	{
	335	const struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpuid);
	336	long timeout;
	337
	338	#ifdef CONFIG_HOTPLUG_CPU
	339	int i;
	340
	341	/* reset irq statistics for this CPU */
	342	memset(&per_cpu(irq_stat, cpuid), 0, sizeof(irq_cpustat_t));
	343	for (i = 0; i < NR_IRQS; i++) {
	344	struct irq_desc *desc = irq_to_desc(i);
	345
	346	if (desc && desc->kstat_irqs)
	347	*per_cpu_ptr(desc->kstat_irqs, cpuid) = (struct irqstat) { };
	348	}
	349	#endif
	350
	351	/* wait until last booting CPU has started. */
	352	while (cpu_now_booting)
	353	;
	354
	355	/* Let _start know what logical CPU we're booting
	356	** (offset into init_tasks[],cpu_data[])
	357	*/
	358	cpu_now_booting = cpuid;
	359
	360	/*
	361	** boot strap code needs to know the task address since
	362	** it also contains the process stack.
	363	*/
	364	smp_init_current_idle_task = idle ;
	365	mb();
	366
	367	printk(KERN_INFO "Releasing cpu %d now, hpa=%lx\n", cpuid, p->hpa);
	368
	369	/*
	370	** This gets PDC to release the CPU from a very tight loop.
	371	**
	372	** From the PA-RISC 2.0 Firmware Architecture Reference Specification:
	373	** "The MEM_RENDEZ vector specifies the location of OS_RENDEZ which
	374	** is executed after receiving the rendezvous signal (an interrupt to
	375	** EIR{0}). MEM_RENDEZ is valid only when it is nonzero and the
	376	** contents of memory are valid."
	377	*/
	378	gsc_writel(TIMER_IRQ - CPU_IRQ_BASE, p->hpa);
	379	mb();
	380
	381	/*
	382	* OK, wait a bit for that CPU to finish staggering about.
	383	* Slave will set a bit when it reaches smp_cpu_init().
	384	* Once the "monarch CPU" sees the bit change, it can move on.
	385	*/
	386	for (timeout = 0; timeout < 10000; timeout++) {
	387	if(cpu_online(cpuid)) {
	388	/* Which implies Slave has started up */
	389	cpu_now_booting = 0;
	390	goto alive ;
	391	}
	392	udelay(100);
	393	barrier();
	394	}
	395	printk(KERN_CRIT "SMP: CPU:%d is stuck.\n", cpuid);
	396	return -1;
	397
	398	alive:
	399	/* Remember the Slave data */
	400	smp_debug(100, KERN_DEBUG "SMP: CPU:%d came alive after %ld _us\n",
	401	cpuid, timeout * 100);
	402	return 0;
	403	}
	404
	405	void __init smp_prepare_boot_cpu(void)
	406	{
	407	pr_info("SMP: bootstrap CPU ID is 0\n");
	408	}
	409
	410
	411
	412	/*
	413	** inventory.c:do_inventory() hasn't yet been run and thus we
	414	** don't 'discover' the additional CPUs until later.
	415	*/
	416	void __init smp_prepare_cpus(unsigned int max_cpus)
	417	{
	418	int cpu;
	419
	420	for_each_possible_cpu(cpu)
	421	spin_lock_init(&per_cpu(ipi_lock, cpu));
	422
	423	init_cpu_present(cpumask_of(0));
	424	}
	425
	426
	427	void __init smp_cpus_done(unsigned int cpu_max)
	428	{
	429	}
	430
	431
	432	int __cpu_up(unsigned int cpu, struct task_struct *tidle)
	433	{
	434	if (cpu_online(cpu))
	435	return 0;
	436
	437	if (num_online_cpus() < nr_cpu_ids &&
	438	num_online_cpus() < setup_max_cpus &&
	439	smp_boot_one_cpu(cpu, tidle))
	440	return -EIO;
	441
	442	return cpu_online(cpu) ? 0 : -EIO;
	443	}
	444
	445	/*
	446	* __cpu_disable runs on the processor to be shutdown.
	447	*/
	448	int __cpu_disable(void)
	449	{
	450	#ifdef CONFIG_HOTPLUG_CPU
	451	unsigned int cpu = smp_processor_id();
	452
	453	remove_cpu_topology(cpu);
	454
	455	/*
	456	* Take this CPU offline. Once we clear this, we can't return,
	457	* and we must not schedule until we're ready to give up the cpu.
	458	*/
	459	set_cpu_online(cpu, false);
	460
	461	/* Find a new timesync master */
	462	if (cpu == time_keeper_id) {
	463	time_keeper_id = cpumask_first(cpu_online_mask);
	464	pr_info("CPU %d is now promoted to time-keeper master\n", time_keeper_id);
	465	}
	466
	467	disable_percpu_irq(IPI_IRQ);
	468
	469	irq_migrate_all_off_this_cpu();
	470
	471	flush_cache_all_local();
	472	flush_tlb_all_local(NULL);
	473
	474	/* disable all irqs, including timer irq */
	475	local_irq_disable();
	476
	477	/* wait for next timer irq ... */
	478	mdelay(1000/HZ+100);
	479
	480	/* ... and then clear all pending external irqs */
	481	set_eiem(0);
	482	mtctl(~0UL, CR_EIRR);
	483	mfctl(CR_EIRR);
	484	mtctl(0, CR_EIRR);
	485	#endif
	486	return 0;
	487	}
	488
	489	/*
	490	* called on the thread which is asking for a CPU to be shutdown -
	491	* waits until shutdown has completed, or it is timed out.
	492	*/
	493	void __cpu_die(unsigned int cpu)
	494	{
	495	pdc_cpu_rendezvous_lock();
	496	}
	497
	498	void arch_cpuhp_cleanup_dead_cpu(unsigned int cpu)
	499	{
	500	pr_info("CPU%u: is shutting down\n", cpu);
	501
	502	/* set task's state to interruptible sleep */
	503	set_current_state(TASK_INTERRUPTIBLE);
	504	schedule_timeout((IS_ENABLED(CONFIG_64BIT) ? 8:2) * HZ);
	505
	506	pdc_cpu_rendezvous_unlock();
	507	}