/* smp.c: Sparc64 SMP support.
 *
 * Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu)
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/threads.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/fs.h>
#include <linux/seq_file.h>
#include <linux/cache.h>
#include <linux/jiffies.h>

#include <asm/head.h>
#include <asm/ptrace.h>
#include <asm/atomic.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
#include <asm/cpudata.h>

#include <asm/irq.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/oplib.h>
#include <asm/hardirq.h>
#include <asm/uaccess.h>
#include <asm/timer.h>
#include <asm/starfire.h>

extern int linux_num_cpus;
extern void calibrate_delay(void);

/* Please don't make this stuff initdata!!!  --DaveM */
static unsigned char boot_cpu_id;

cpumask_t cpu_online_map = CPU_MASK_NONE;
cpumask_t phys_cpu_present_map = CPU_MASK_NONE;
static cpumask_t smp_commenced_mask;
static cpumask_t cpu_callout_map;

void smp_info(struct seq_file *m)
{
	int i;
	
	seq_printf(m, "State:\n");
	for (i = 0; i < NR_CPUS; i++) {
		if (cpu_online(i))
			seq_printf(m,
				   "CPU%d:\t\tonline\n", i);
	}
}

void smp_bogo(struct seq_file *m)
{
	int i;
	
	for (i = 0; i < NR_CPUS; i++)
		if (cpu_online(i))
			seq_printf(m,
				   "Cpu%dBogo\t: %lu.%02lu\n"
				   "Cpu%dClkTck\t: %016lx\n",
				   i, cpu_data(i).udelay_val / (500000/HZ),
				   (cpu_data(i).udelay_val / (5000/HZ)) % 100,
				   i, cpu_data(i).clock_tick);
}

void __init smp_store_cpu_info(int id)
{
	int cpu_node;

	/* multiplier and counter set by
	   smp_setup_percpu_timer()  */
	cpu_data(id).udelay_val			= loops_per_jiffy;

	cpu_find_by_mid(id, &cpu_node);
	cpu_data(id).clock_tick = prom_getintdefault(cpu_node,
						     "clock-frequency", 0);

	cpu_data(id).pgcache_size		= 0;
	cpu_data(id).pte_cache[0]		= NULL;
	cpu_data(id).pte_cache[1]		= NULL;
	cpu_data(id).pgdcache_size		= 0;
	cpu_data(id).pgd_cache			= NULL;
	cpu_data(id).idle_volume		= 1;
}

static void smp_setup_percpu_timer(void);

static volatile unsigned long callin_flag = 0;

extern void inherit_locked_prom_mappings(int save_p);

void __init smp_callin(void)
{
	int cpuid = hard_smp_processor_id();
	extern int bigkernel;
	extern unsigned long kern_locked_tte_data;

	if (bigkernel) {
		prom_dtlb_load(sparc64_highest_locked_tlbent()-1, 
			kern_locked_tte_data + 0x400000, KERNBASE + 0x400000);
		prom_itlb_load(sparc64_highest_locked_tlbent()-1, 
			kern_locked_tte_data + 0x400000, KERNBASE + 0x400000);
	}

	inherit_locked_prom_mappings(0);

	__flush_tlb_all();

	smp_setup_percpu_timer();

	local_irq_enable();

	calibrate_delay();
	smp_store_cpu_info(cpuid);
	callin_flag = 1;
	__asm__ __volatile__("membar #Sync\n\t"
			     "flush  %%g6" : : : "memory");

	/* Clear this or we will die instantly when we
	 * schedule back to this idler...
	 */
	clear_thread_flag(TIF_NEWCHILD);

	/* Attach to the address space of init_task. */
	atomic_inc(&init_mm.mm_count);
	current->active_mm = &init_mm;

	while (!cpu_isset(cpuid, smp_commenced_mask))
		membar("#LoadLoad");

	cpu_set(cpuid, cpu_online_map);
}

void cpu_panic(void)
{
	printk("CPU[%d]: Returns from cpu_idle!\n", smp_processor_id());
	panic("SMP bolixed\n");
}

static unsigned long current_tick_offset;

/* This tick register synchronization scheme is taken entirely from
 * the ia64 port, see arch/ia64/kernel/smpboot.c for details and credit.
 *
 * The only change I've made is to rework it so that the master
 * initiates the synchonization instead of the slave. -DaveM
 */

#define MASTER	0
#define SLAVE	(SMP_CACHE_BYTES/sizeof(unsigned long))

#define NUM_ROUNDS	64	/* magic value */
#define NUM_ITERS	5	/* likewise */

static spinlock_t itc_sync_lock = SPIN_LOCK_UNLOCKED;
static unsigned long go[SLAVE + 1];

#define DEBUG_TICK_SYNC	0

static inline long get_delta (long *rt, long *master)
{
	unsigned long best_t0 = 0, best_t1 = ~0UL, best_tm = 0;
	unsigned long tcenter, t0, t1, tm;
	unsigned long i;

	for (i = 0; i < NUM_ITERS; i++) {
		t0 = tick_ops->get_tick();
		go[MASTER] = 1;
		membar("#StoreLoad");
		while (!(tm = go[SLAVE]))
			membar("#LoadLoad");
		go[SLAVE] = 0;
		membar("#StoreStore");
		t1 = tick_ops->get_tick();

		if (t1 - t0 < best_t1 - best_t0)
			best_t0 = t0, best_t1 = t1, best_tm = tm;
	}

	*rt = best_t1 - best_t0;
	*master = best_tm - best_t0;

	/* average best_t0 and best_t1 without overflow: */
	tcenter = (best_t0/2 + best_t1/2);
	if (best_t0 % 2 + best_t1 % 2 == 2)
		tcenter++;
	return tcenter - best_tm;
}

void smp_synchronize_tick_client(void)
{
	long i, delta, adj, adjust_latency = 0, done = 0;
	unsigned long flags, rt, master_time_stamp, bound;
#if DEBUG_TICK_SYNC
	struct {
		long rt;	/* roundtrip time */
		long master;	/* master's timestamp */
		long diff;	/* difference between midpoint and master's timestamp */
		long lat;	/* estimate of itc adjustment latency */
	} t[NUM_ROUNDS];
#endif

	go[MASTER] = 1;

	while (go[MASTER])
		membar("#LoadLoad");

	local_irq_save(flags);
	{
		for (i = 0; i < NUM_ROUNDS; i++) {
			delta = get_delta(&rt, &master_time_stamp);
			if (delta == 0) {
				done = 1;	/* let's lock on to this... */
				bound = rt;
			}

			if (!done) {
				if (i > 0) {
					adjust_latency += -delta;
					adj = -delta + adjust_latency/4;
				} else
					adj = -delta;

				tick_ops->add_tick(adj, current_tick_offset);
			}
#if DEBUG_TICK_SYNC
			t[i].rt = rt;
			t[i].master = master_time_stamp;
			t[i].diff = delta;
			t[i].lat = adjust_latency/4;
#endif
		}
	}
	local_irq_restore(flags);

#if DEBUG_TICK_SYNC
	for (i = 0; i < NUM_ROUNDS; i++)
		printk("rt=%5ld master=%5ld diff=%5ld adjlat=%5ld\n",
		       t[i].rt, t[i].master, t[i].diff, t[i].lat);
#endif

	printk(KERN_INFO "CPU %d: synchronized TICK with master CPU (last diff %ld cycles,"
	       "maxerr %lu cycles)\n", smp_processor_id(), delta, rt);
}

static void smp_start_sync_tick_client(int cpu);

static void smp_synchronize_one_tick(int cpu)
{
	unsigned long flags, i;

	go[MASTER] = 0;

	smp_start_sync_tick_client(cpu);

	/* wait for client to be ready */
	while (!go[MASTER])
		membar("#LoadLoad");

	/* now let the client proceed into his loop */
	go[MASTER] = 0;
	membar("#StoreLoad");

	spin_lock_irqsave(&itc_sync_lock, flags);
	{
		for (i = 0; i < NUM_ROUNDS*NUM_ITERS; i++) {
			while (!go[MASTER])
				membar("#LoadLoad");
			go[MASTER] = 0;
			membar("#StoreStore");
			go[SLAVE] = tick_ops->get_tick();
			membar("#StoreLoad");
		}
	}
	spin_unlock_irqrestore(&itc_sync_lock, flags);
}

extern unsigned long sparc64_cpu_startup;

/* The OBP cpu startup callback truncates the 3rd arg cookie to
 * 32-bits (I think) so to be safe we have it read the pointer
 * contained here so we work on >4GB machines. -DaveM
 */
static struct thread_info *cpu_new_thread = NULL;

static int __devinit smp_boot_one_cpu(unsigned int cpu)
{
	unsigned long entry =
		(unsigned long)(&sparc64_cpu_startup);
	unsigned long cookie =
		(unsigned long)(&cpu_new_thread);
	struct task_struct *p;
	int timeout, ret, cpu_node;

	kernel_thread(NULL, NULL, CLONE_IDLETASK);

	p = prev_task(&init_task);

	init_idle(p, cpu);

	unhash_process(p);

	callin_flag = 0;
	cpu_new_thread = p->thread_info;
	cpu_set(cpu, cpu_callout_map);

	cpu_find_by_mid(cpu, &cpu_node);
	prom_startcpu(cpu_node, entry, cookie);

	for (timeout = 0; timeout < 5000000; timeout++) {
		if (callin_flag)
			break;
		udelay(100);
	}
	if (callin_flag) {
		ret = 0;
	} else {
		printk("Processor %d is stuck.\n", cpu);
		cpu_clear(cpu, cpu_callout_map);
		ret = -ENODEV;
	}
	cpu_new_thread = NULL;

	return ret;
}

static void spitfire_xcall_helper(u64 data0, u64 data1, u64 data2, u64 pstate, unsigned long cpu)
{
	u64 result, target;
	int stuck, tmp;

	if (this_is_starfire) {
		/* map to real upaid */
		cpu = (((cpu & 0x3c) << 1) |
			((cpu & 0x40) >> 4) |
			(cpu & 0x3));
	}

	target = (cpu << 14) | 0x70;
again:
	/* Ok, this is the real Spitfire Errata #54.
	 * One must read back from a UDB internal register
	 * after writes to the UDB interrupt dispatch, but
	 * before the membar Sync for that write.
	 * So we use the high UDB control register (ASI 0x7f,
	 * ADDR 0x20) for the dummy read. -DaveM
	 */
	tmp = 0x40;
	__asm__ __volatile__(
	"wrpr	%1, %2, %%pstate\n\t"
	"stxa	%4, [%0] %3\n\t"
	"stxa	%5, [%0+%8] %3\n\t"
	"add	%0, %8, %0\n\t"
	"stxa	%6, [%0+%8] %3\n\t"
	"membar	#Sync\n\t"
	"stxa	%%g0, [%7] %3\n\t"
	"membar	#Sync\n\t"
	"mov	0x20, %%g1\n\t"
	"ldxa	[%%g1] 0x7f, %%g0\n\t"
	"membar	#Sync"
	: "=r" (tmp)
	: "r" (pstate), "i" (PSTATE_IE), "i" (ASI_INTR_W),
	  "r" (data0), "r" (data1), "r" (data2), "r" (target),
	  "r" (0x10), "0" (tmp)
        : "g1");

	/* NOTE: PSTATE_IE is still clear. */
	stuck = 100000;
	do {
		__asm__ __volatile__("ldxa [%%g0] %1, %0"
			: "=r" (result)
			: "i" (ASI_INTR_DISPATCH_STAT));
		if (result == 0) {
			__asm__ __volatile__("wrpr %0, 0x0, %%pstate"
					     : : "r" (pstate));
			return;
		}
		stuck -= 1;
		if (stuck == 0)
			break;
	} while (result & 0x1);
	__asm__ __volatile__("wrpr %0, 0x0, %%pstate"
			     : : "r" (pstate));
	if (stuck == 0) {
		printk("CPU[%d]: mondo stuckage result[%016lx]\n",
		       smp_processor_id(), result);
	} else {
		udelay(2);
		goto again;
	}
}

static __inline__ void spitfire_xcall_deliver(u64 data0, u64 data1, u64 data2, cpumask_t mask)
{
	u64 pstate;
	int i;

	__asm__ __volatile__("rdpr %%pstate, %0" : "=r" (pstate));
	for (i = 0; i < NR_CPUS; i++) {
		if (cpu_isset(i, mask)) {
			spitfire_xcall_helper(data0, data1, data2, pstate, i);
			cpu_clear(i, mask);
			if (cpus_empty(mask))
				break;
		}
	}
}

/* Cheetah now allows to send the whole 64-bytes of data in the interrupt
 * packet, but we have no use for that.  However we do take advantage of
 * the new pipelining feature (ie. dispatch to multiple cpus simultaneously).
 */
#if NR_CPUS > 32
#error Fixup cheetah_xcall_deliver Dave...
#endif
static void cheetah_xcall_deliver(u64 data0, u64 data1, u64 data2, cpumask_t mask)
{
	u64 pstate, ver;
	int nack_busy_id, is_jalapeno;

	if (cpus_empty(mask))
		return;

	/* Unfortunately, someone at Sun had the brilliant idea to make the
	 * busy/nack fields hard-coded by ITID number for this Ultra-III
	 * derivative processor.
	 */
	__asm__ ("rdpr %%ver, %0" : "=r" (ver));
	is_jalapeno = ((ver >> 32) == 0x003e0016);

	__asm__ __volatile__("rdpr %%pstate, %0" : "=r" (pstate));

retry:
	__asm__ __volatile__("wrpr %0, %1, %%pstate\n\t"
			     : : "r" (pstate), "i" (PSTATE_IE));

	/* Setup the dispatch data registers. */
	__asm__ __volatile__("stxa	%0, [%3] %6\n\t"
			     "stxa	%1, [%4] %6\n\t"
			     "stxa	%2, [%5] %6\n\t"
			     "membar	#Sync\n\t"
			     : /* no outputs */
			     : "r" (data0), "r" (data1), "r" (data2),
			       "r" (0x40), "r" (0x50), "r" (0x60),
			       "i" (ASI_INTR_W));

	nack_busy_id = 0;
	{
		cpumask_t work_mask = mask;
		int i;

		for (i = 0; i < NR_CPUS; i++) {
			if (cpu_isset(i, work_mask)) {
				u64 target = (i << 14) | 0x70;

				if (!is_jalapeno)
					target |= (nack_busy_id << 24);
				__asm__ __volatile__(
					"stxa	%%g0, [%0] %1\n\t"
					"membar	#Sync\n\t"
					: /* no outputs */
					: "r" (target), "i" (ASI_INTR_W));
				nack_busy_id++;
 				cpu_clear(i, work_mask);
				if (cpus_empty(work_mask))
					break;
			}
		}
	}

	/* Now, poll for completion. */
	{
		u64 dispatch_stat;
		long stuck;

		stuck = 100000 * nack_busy_id;
		do {
			__asm__ __volatile__("ldxa	[%%g0] %1, %0"
					     : "=r" (dispatch_stat)
					     : "i" (ASI_INTR_DISPATCH_STAT));
			if (dispatch_stat == 0UL) {
				__asm__ __volatile__("wrpr %0, 0x0, %%pstate"
						     : : "r" (pstate));
				return;
			}
			if (!--stuck)
				break;
		} while (dispatch_stat & 0x5555555555555555UL);

		__asm__ __volatile__("wrpr %0, 0x0, %%pstate"
				     : : "r" (pstate));

		if ((dispatch_stat & ~(0x5555555555555555UL)) == 0) {
			/* Busy bits will not clear, continue instead
			 * of freezing up on this cpu.
			 */
			printk("CPU[%d]: mondo stuckage result[%016lx]\n",
			       smp_processor_id(), dispatch_stat);
		} else {
			cpumask_t work_mask = mask;
			int i, this_busy_nack = 0;

			/* Delay some random time with interrupts enabled
			 * to prevent deadlock.
			 */
			udelay(2 * nack_busy_id);

			/* Clear out the mask bits for cpus which did not
			 * NACK us.
			 */
			for (i = 0; i < NR_CPUS; i++) {
				if (cpu_isset(i, work_mask)) {
					u64 check_mask;

					if (is_jalapeno)
						check_mask = (0x2UL << (2*i));
					else
						check_mask = (0x2UL <<
							      this_busy_nack);
					if ((dispatch_stat & check_mask) == 0)
						cpu_clear(i, mask);
					this_busy_nack += 2;
					cpu_clear(i, work_mask);
					if (cpus_empty(work_mask))
						break;
				}
			}

			goto retry;
		}
	}
}

/* Send cross call to all processors mentioned in MASK
 * except self.
 */
static void smp_cross_call_masked(unsigned long *func, u32 ctx, u64 data1, u64 data2, cpumask_t mask)
{
	u64 data0 = (((u64)ctx)<<32 | (((u64)func) & 0xffffffff));

	cpus_and(mask, mask, cpu_online_map);
	cpu_clear(smp_processor_id(), mask);

	if (tlb_type == spitfire)
		spitfire_xcall_deliver(data0, data1, data2, mask);
	else
		cheetah_xcall_deliver(data0, data1, data2, mask);
	/* NOTE: Caller runs local copy on master. */
}

extern unsigned long xcall_sync_tick;

static void smp_start_sync_tick_client(int cpu)
{
	cpumask_t mask = cpumask_of_cpu(cpu);

	smp_cross_call_masked(&xcall_sync_tick,
			      0, 0, 0, mask);
}

/* Send cross call to all processors except self. */
#define smp_cross_call(func, ctx, data1, data2) \
	smp_cross_call_masked(func, ctx, data1, data2, cpu_online_map)

struct call_data_struct {
	void (*func) (void *info);
	void *info;
	atomic_t finished;
	int wait;
};

static spinlock_t call_lock = SPIN_LOCK_UNLOCKED;
static struct call_data_struct *call_data;

extern unsigned long xcall_call_function;

/*
 * You must not call this function with disabled interrupts or from a
 * hardware interrupt handler or from a bottom half handler.
 */
int smp_call_function(void (*func)(void *info), void *info,
		      int nonatomic, int wait)
{
	struct call_data_struct data;
	int cpus = num_online_cpus() - 1;
	long timeout;

	if (!cpus)
		return 0;

	data.func = func;
	data.info = info;
	atomic_set(&data.finished, 0);
	data.wait = wait;

	spin_lock(&call_lock);

	call_data = &data;

	smp_cross_call(&xcall_call_function, 0, 0, 0);

	/* 
	 * Wait for other cpus to complete function or at
	 * least snap the call data.
	 */
	timeout = 1000000;
	while (atomic_read(&data.finished) != cpus) {
		if (--timeout <= 0)
			goto out_timeout;
		barrier();
		udelay(1);
	}

	spin_unlock(&call_lock);

	return 0;

out_timeout:
	spin_unlock(&call_lock);
	printk("XCALL: Remote cpus not responding, ncpus=%ld finished=%ld\n",
	       (long) num_online_cpus() - 1L,
	       (long) atomic_read(&data.finished));
	return 0;
}

void smp_call_function_client(int irq, struct pt_regs *regs)
{
	void (*func) (void *info) = call_data->func;
	void *info = call_data->info;

	clear_softint(1 << irq);
	if (call_data->wait) {
		/* let initiator proceed only after completion */
		func(info);
		atomic_inc(&call_data->finished);
	} else {
		/* let initiator proceed after getting data */
		atomic_inc(&call_data->finished);
		func(info);
	}
}

extern unsigned long xcall_flush_tlb_page;
extern unsigned long xcall_flush_tlb_mm;
extern unsigned long xcall_flush_tlb_range;
extern unsigned long xcall_flush_tlb_kernel_range;
extern unsigned long xcall_flush_tlb_all_spitfire;
extern unsigned long xcall_flush_tlb_all_cheetah;
extern unsigned long xcall_report_regs;
extern unsigned long xcall_receive_signal;
extern unsigned long xcall_flush_dcache_page_cheetah;
extern unsigned long xcall_flush_dcache_page_spitfire;

#ifdef CONFIG_DEBUG_DCFLUSH
extern atomic_t dcpage_flushes;
extern atomic_t dcpage_flushes_xcall;
#endif

static __inline__ void __local_flush_dcache_page(struct page *page)
{
#if (L1DCACHE_SIZE > PAGE_SIZE)
	__flush_dcache_page(page->virtual,
			    ((tlb_type == spitfire) &&
			     page_mapping(page) != NULL));
#else
	if (page_mapping(page) != NULL &&
	    tlb_type == spitfire)
		__flush_icache_page(__pa(page->virtual));
#endif
}

void smp_flush_dcache_page_impl(struct page *page, int cpu)
{
	cpumask_t mask = cpumask_of_cpu(cpu);

#ifdef CONFIG_DEBUG_DCFLUSH
	atomic_inc(&dcpage_flushes);
#endif
	if (cpu == smp_processor_id()) {
		__local_flush_dcache_page(page);
	} else if (cpu_online(cpu)) {
		u64 data0;

		if (tlb_type == spitfire) {
			data0 =
				((u64)&xcall_flush_dcache_page_spitfire);
			if (page_mapping(page) != NULL)
				data0 |= ((u64)1 << 32);
			spitfire_xcall_deliver(data0,
					       __pa(page->virtual),
					       (u64) page->virtual,
					       mask);
		} else {
			data0 =
				((u64)&xcall_flush_dcache_page_cheetah);
			cheetah_xcall_deliver(data0,
					      __pa(page->virtual),
					      0, mask);
		}
#ifdef CONFIG_DEBUG_DCFLUSH
		atomic_inc(&dcpage_flushes_xcall);
#endif
	}
}

void flush_dcache_page_all(struct mm_struct *mm, struct page *page)
{
	cpumask_t mask = cpu_online_map;
	u64 data0;

	cpu_clear(smp_processor_id(), mask);

#ifdef CONFIG_DEBUG_DCFLUSH
	atomic_inc(&dcpage_flushes);
#endif
	if (cpus_empty(mask))
		goto flush_self;
	if (tlb_type == spitfire) {
		data0 = ((u64)&xcall_flush_dcache_page_spitfire);
		if (page_mapping(page) != NULL)
			data0 |= ((u64)1 << 32);
		spitfire_xcall_deliver(data0,
				       __pa(page->virtual),
				       (u64) page->virtual,
				       mask);
	} else {
		data0 = ((u64)&xcall_flush_dcache_page_cheetah);
		cheetah_xcall_deliver(data0,
				      __pa(page->virtual),
				      0, mask);
	}
#ifdef CONFIG_DEBUG_DCFLUSH
	atomic_inc(&dcpage_flushes_xcall);
#endif
 flush_self:
	__local_flush_dcache_page(page);
}

void smp_receive_signal(int cpu)
{
	cpumask_t mask = cpumask_of_cpu(cpu);

	if (cpu_online(cpu)) {
		u64 data0 = (((u64)&xcall_receive_signal) & 0xffffffff);

		if (tlb_type == spitfire)
			spitfire_xcall_deliver(data0, 0, 0, mask);
		else
			cheetah_xcall_deliver(data0, 0, 0, mask);
	}
}

void smp_receive_signal_client(int irq, struct pt_regs *regs)
{
	/* Just return, rtrap takes care of the rest. */
	clear_softint(1 << irq);
}

void smp_report_regs(void)
{
	smp_cross_call(&xcall_report_regs, 0, 0, 0);
}

void smp_flush_tlb_all(void)
{
	if (tlb_type == spitfire)
		smp_cross_call(&xcall_flush_tlb_all_spitfire, 0, 0, 0);
	else
		smp_cross_call(&xcall_flush_tlb_all_cheetah, 0, 0, 0);
	__flush_tlb_all();
}

/* We know that the window frames of the user have been flushed
 * to the stack before we get here because all callers of us
 * are flush_tlb_*() routines, and these run after flush_cache_*()
 * which performs the flushw.
 *
 * The SMP TLB coherency scheme we use works as follows:
 *
 * 1) mm->cpu_vm_mask is a bit mask of which cpus an address
 *    space has (potentially) executed on, this is the heuristic
 *    we use to avoid doing cross calls.
 *
 *    Also, for flushing from kswapd and also for clones, we
 *    use cpu_vm_mask as the list of cpus to make run the TLB.
 *
 * 2) TLB context numbers are shared globally across all processors
 *    in the system, this allows us to play several games to avoid
 *    cross calls.
 *
 *    One invariant is that when a cpu switches to a process, and
 *    that processes tsk->active_mm->cpu_vm_mask does not have the
 *    current cpu's bit set, that tlb context is flushed locally.
 *
 *    If the address space is non-shared (ie. mm->count == 1) we avoid
 *    cross calls when we want to flush the currently running process's
 *    tlb state.  This is done by clearing all cpu bits except the current
 *    processor's in current->active_mm->cpu_vm_mask and performing the
 *    flush locally only.  This will force any subsequent cpus which run
 *    this task to flush the context from the local tlb if the process
 *    migrates to another cpu (again).
 *
 * 3) For shared address spaces (threads) and swapping we bite the
 *    bullet for most cases and perform the cross call (but only to
 *    the cpus listed in cpu_vm_mask).
 *
 *    The performance gain from "optimizing" away the cross call for threads is
 *    questionable (in theory the big win for threads is the massive sharing of
 *    address space state across processors).
 */
void smp_flush_tlb_mm(struct mm_struct *mm)
{
        /*
         * This code is called from two places, dup_mmap and exit_mmap. In the
         * former case, we really need a flush. In the later case, the callers
         * are single threaded exec_mmap (really need a flush), multithreaded
         * exec_mmap case (do not need to flush, since the caller gets a new
         * context via activate_mm), and all other callers of mmput() whence
         * the flush can be optimized since the associated threads are dead and
         * the mm is being torn down (__exit_mm and other mmput callers) or the
         * owning thread is dissociating itself from the mm. The
         * (atomic_read(&mm->mm_users) == 0) check ensures real work is done
         * for single thread exec and dup_mmap cases. An alternate check might
         * have been (current->mm != mm).
         *                                              Kanoj Sarcar
         */
        if (atomic_read(&mm->mm_users) == 0)
                return;

	{
		u32 ctx = CTX_HWBITS(mm->context);
		int cpu = smp_processor_id();

		if (atomic_read(&mm->mm_users) == 1) {
			/* See smp_flush_tlb_page for info about this. */
			mm->cpu_vm_mask = cpumask_of_cpu(cpu);
			goto local_flush_and_out;
		}

		smp_cross_call_masked(&xcall_flush_tlb_mm,
				      ctx, 0, 0,
				      mm->cpu_vm_mask);

	local_flush_and_out:
		__flush_tlb_mm(ctx, SECONDARY_CONTEXT);
	}
}

void smp_flush_tlb_range(struct mm_struct *mm, unsigned long start,
			 unsigned long end)
{
	u32 ctx = CTX_HWBITS(mm->context);
	int cpu = smp_processor_id();

	start &= PAGE_MASK;
	end    = PAGE_ALIGN(end);

	if (mm == current->active_mm && atomic_read(&mm->mm_users) == 1) {
		mm->cpu_vm_mask = cpumask_of_cpu(cpu);
		goto local_flush_and_out;
	}

	smp_cross_call_masked(&xcall_flush_tlb_range,
			      ctx, start, end,
			      mm->cpu_vm_mask);

 local_flush_and_out:
	__flush_tlb_range(ctx, start, SECONDARY_CONTEXT,
			  end, PAGE_SIZE, (end-start));
}

void smp_flush_tlb_kernel_range(unsigned long start, unsigned long end)
{
	start &= PAGE_MASK;
	end    = PAGE_ALIGN(end);
	if (start != end) {
		smp_cross_call(&xcall_flush_tlb_kernel_range,
			       0, start, end);

		__flush_tlb_kernel_range(start, end);
	}
}

void smp_flush_tlb_page(struct mm_struct *mm, unsigned long page)
{
	{
		u32 ctx = CTX_HWBITS(mm->context);
		int cpu = smp_processor_id();

		page &= PAGE_MASK;
		if (mm == current->active_mm &&
		    atomic_read(&mm->mm_users) == 1) {
			/* By virtue of being the current address space, and
			 * having the only reference to it, the following
			 * operation is safe.
			 *
			 * It would not be a win to perform the xcall tlb
			 * flush in this case, because even if we switch back
			 * to one of the other processors in cpu_vm_mask it
			 * is almost certain that all TLB entries for this
			 * context will be replaced by the time that happens.
			 */
			mm->cpu_vm_mask = cpumask_of_cpu(cpu);
			goto local_flush_and_out;
		} else {
			cpumask_t this_cpu_mask = cpumask_of_cpu(cpu);

			/* By virtue of running under the mm->page_table_lock,
			 * and mmu_context.h:switch_mm doing the same, the
			 * following operation is safe.
			 */
			if (cpus_equal(mm->cpu_vm_mask, this_cpu_mask))
				goto local_flush_and_out;
		}

		/* OK, we have to actually perform the cross call.  Most
		 * likely this is a cloned mm or kswapd is kicking out pages
		 * for a task which has run recently on another cpu.
		 */
		smp_cross_call_masked(&xcall_flush_tlb_page,
				      ctx, page, 0,
				      mm->cpu_vm_mask);
		if (!cpu_isset(cpu, mm->cpu_vm_mask))
			return;

	local_flush_and_out:
		__flush_tlb_page(ctx, page, SECONDARY_CONTEXT);
	}
}

/* CPU capture. */
/* #define CAPTURE_DEBUG */
extern unsigned long xcall_capture;

static atomic_t smp_capture_depth = ATOMIC_INIT(0);
static atomic_t smp_capture_registry = ATOMIC_INIT(0);
static unsigned long penguins_are_doing_time;

void smp_capture(void)
{
	int result = __atomic_add(1, &smp_capture_depth);

	membar("#StoreStore | #LoadStore");
	if (result == 1) {
		int ncpus = num_online_cpus();

#ifdef CAPTURE_DEBUG
		printk("CPU[%d]: Sending penguins to jail...",
		       smp_processor_id());
#endif
		penguins_are_doing_time = 1;
		membar("#StoreStore | #LoadStore");
		atomic_inc(&smp_capture_registry);
		smp_cross_call(&xcall_capture, 0, 0, 0);
		while (atomic_read(&smp_capture_registry) != ncpus)
			membar("#LoadLoad");
#ifdef CAPTURE_DEBUG
		printk("done\n");
#endif
	}
}

void smp_release(void)
{
	if (atomic_dec_and_test(&smp_capture_depth)) {
#ifdef CAPTURE_DEBUG
		printk("CPU[%d]: Giving pardon to "
		       "imprisoned penguins\n",
		       smp_processor_id());
#endif
		penguins_are_doing_time = 0;
		membar("#StoreStore | #StoreLoad");
		atomic_dec(&smp_capture_registry);
	}
}

/* Imprisoned penguins run with %pil == 15, but PSTATE_IE set, so they
 * can service tlb flush xcalls...
 */
extern void prom_world(int);
extern void save_alternate_globals(unsigned long *);
extern void restore_alternate_globals(unsigned long *);
void smp_penguin_jailcell(int irq, struct pt_regs *regs)
{
	unsigned long global_save[24];

	clear_softint(1 << irq);

	preempt_disable();

	__asm__ __volatile__("flushw");
	save_alternate_globals(global_save);
	prom_world(1);
	atomic_inc(&smp_capture_registry);
	membar("#StoreLoad | #StoreStore");
	while (penguins_are_doing_time)
		membar("#LoadLoad");
	restore_alternate_globals(global_save);
	atomic_dec(&smp_capture_registry);
	prom_world(0);

	preempt_enable();
}

extern unsigned long xcall_promstop;

void smp_promstop_others(void)
{
	smp_cross_call(&xcall_promstop, 0, 0, 0);
}

extern void sparc64_do_profile(struct pt_regs *regs);

#define prof_multiplier(__cpu)		cpu_data(__cpu).multiplier
#define prof_counter(__cpu)		cpu_data(__cpu).counter

void smp_percpu_timer_interrupt(struct pt_regs *regs)
{
	unsigned long compare, tick, pstate;
	int cpu = smp_processor_id();
	int user = user_mode(regs);

	/*
	 * Check for level 14 softint.
	 */
	{
		unsigned long tick_mask = tick_ops->softint_mask;

		if (!(get_softint() & tick_mask)) {
			extern void handler_irq(int, struct pt_regs *);

			handler_irq(14, regs);
			return;
		}
		clear_softint(tick_mask);
	}

	do {
		sparc64_do_profile(regs);
		if (!--prof_counter(cpu)) {
			irq_enter();

			if (cpu == boot_cpu_id) {
				kstat_this_cpu.irqs[0]++;
				timer_tick_interrupt(regs);
			}

			update_process_times(user);

			irq_exit();

			prof_counter(cpu) = prof_multiplier(cpu);
		}

		/* Guarantee that the following sequences execute
		 * uninterrupted.
		 */
		__asm__ __volatile__("rdpr	%%pstate, %0\n\t"
				     "wrpr	%0, %1, %%pstate"
				     : "=r" (pstate)
				     : "i" (PSTATE_IE));

		compare = tick_ops->add_compare(current_tick_offset);
		tick = tick_ops->get_tick();

		/* Restore PSTATE_IE. */
		__asm__ __volatile__("wrpr	%0, 0x0, %%pstate"
				     : /* no outputs */
				     : "r" (pstate));
	} while (time_after_eq(tick, compare));
}

static void __init smp_setup_percpu_timer(void)
{
	int cpu = smp_processor_id();
	unsigned long pstate;

	prof_counter(cpu) = prof_multiplier(cpu) = 1;

	/* Guarantee that the following sequences execute
	 * uninterrupted.
	 */
	__asm__ __volatile__("rdpr	%%pstate, %0\n\t"
			     "wrpr	%0, %1, %%pstate"
			     : "=r" (pstate)
			     : "i" (PSTATE_IE));

	tick_ops->init_tick(current_tick_offset);

	/* Restore PSTATE_IE. */
	__asm__ __volatile__("wrpr	%0, 0x0, %%pstate"
			     : /* no outputs */
			     : "r" (pstate));
}

void __init smp_tick_init(void)
{
	boot_cpu_id = hard_smp_processor_id();
	current_tick_offset = timer_tick_offset;

	if (boot_cpu_id >= NR_CPUS) {
		prom_printf("Serious problem, boot cpu id >= NR_CPUS\n");
		prom_halt();
	}

	cpu_set(boot_cpu_id, cpu_online_map);
	prof_counter(boot_cpu_id) = prof_multiplier(boot_cpu_id) = 1;
}

cycles_t cacheflush_time;
unsigned long cache_decay_ticks;

extern unsigned long cheetah_tune_scheduling(void);

static void __init smp_tune_scheduling(void)
{
	unsigned long orig_flush_base, flush_base, flags, *p;
	unsigned int ecache_size, order;
	cycles_t tick1, tick2, raw;
	int cpu_node;

	/* Approximate heuristic for SMP scheduling.  It is an
	 * estimation of the time it takes to flush the L2 cache
	 * on the local processor.
	 *
	 * The ia32 chooses to use the L1 cache flush time instead,
	 * and I consider this complete nonsense.  The Ultra can service
	 * a miss to the L1 with a hit to the L2 in 7 or 8 cycles, and
	 * L2 misses are what create extra bus traffic (ie. the "cost"
	 * of moving a process from one cpu to another).
	 */
	printk("SMP: Calibrating ecache flush... ");
	if (tlb_type == cheetah || tlb_type == cheetah_plus) {
		cacheflush_time = cheetah_tune_scheduling();
		goto report;
	}

	cpu_find_by_instance(0, &cpu_node, NULL);
	ecache_size = prom_getintdefault(cpu_node,
					 "ecache-size", (512 * 1024));
	if (ecache_size > (4 * 1024 * 1024))
		ecache_size = (4 * 1024 * 1024);
	orig_flush_base = flush_base =
		__get_free_pages(GFP_KERNEL, order = get_order(ecache_size));

	if (flush_base != 0UL) {
		local_irq_save(flags);

		/* Scan twice the size once just to get the TLB entries
		 * loaded and make sure the second scan measures pure misses.
		 */
		for (p = (unsigned long *)flush_base;
		     ((unsigned long)p) < (flush_base + (ecache_size<<1));
		     p += (64 / sizeof(unsigned long)))
			*((volatile unsigned long *)p);

		tick1 = tick_ops->get_tick();

		__asm__ __volatile__("1:\n\t"
				     "ldx	[%0 + 0x000], %%g1\n\t"
				     "ldx	[%0 + 0x040], %%g2\n\t"
				     "ldx	[%0 + 0x080], %%g3\n\t"
				     "ldx	[%0 + 0x0c0], %%g5\n\t"
				     "add	%0, 0x100, %0\n\t"
				     "cmp	%0, %2\n\t"
				     "bne,pt	%%xcc, 1b\n\t"
				     " nop"
				     : "=&r" (flush_base)
				     : "0" (flush_base),
				       "r" (flush_base + ecache_size)
				     : "g1", "g2", "g3", "g5");

		tick2 = tick_ops->get_tick();

		local_irq_restore(flags);

		raw = (tick2 - tick1);

		/* Dampen it a little, considering two processes
		 * sharing the cache and fitting.
		 */
		cacheflush_time = (raw - (raw >> 2));

		free_pages(orig_flush_base, order);
	} else {
		cacheflush_time = ((ecache_size << 2) +
				   (ecache_size << 1));
	}
report:
	/* Convert ticks/sticks to jiffies. */
	cache_decay_ticks = cacheflush_time / timer_tick_offset;
	if (cache_decay_ticks < 1)
		cache_decay_ticks = 1;

	printk("Using heuristic of %ld cycles, %ld ticks.\n",
	       cacheflush_time, cache_decay_ticks);
}

/* /proc/profile writes can call this, don't __init it please. */
static spinlock_t prof_setup_lock = SPIN_LOCK_UNLOCKED;

int setup_profiling_timer(unsigned int multiplier)
{
	unsigned long flags;
	int i;

	if ((!multiplier) || (timer_tick_offset / multiplier) < 1000)
		return -EINVAL;

	spin_lock_irqsave(&prof_setup_lock, flags);
	for (i = 0; i < NR_CPUS; i++)
		prof_multiplier(i) = multiplier;
	current_tick_offset = (timer_tick_offset / multiplier);
	spin_unlock_irqrestore(&prof_setup_lock, flags);

	return 0;
}

void __init smp_prepare_cpus(unsigned int max_cpus)
{
	int instance, mid;

	instance = 0;
	while (!cpu_find_by_instance(instance, NULL, &mid)) {
		if (mid < max_cpus)
			cpu_set(mid, phys_cpu_present_map);
		instance++;
	}

	if (num_possible_cpus() > max_cpus) {
		instance = 0;
		while (!cpu_find_by_instance(instance, NULL, &mid)) {
			if (mid != boot_cpu_id) {
				cpu_clear(mid, phys_cpu_present_map);
				if (num_possible_cpus() <= max_cpus)
					break;
			}
			instance++;
		}
	}

	smp_store_cpu_info(boot_cpu_id);
}

void __devinit smp_prepare_boot_cpu(void)
{
	current_thread_info()->cpu = hard_smp_processor_id();
	cpu_set(smp_processor_id(), cpu_online_map);
	cpu_set(smp_processor_id(), phys_cpu_present_map);
}

int __devinit __cpu_up(unsigned int cpu)
{
	int ret = smp_boot_one_cpu(cpu);

	if (!ret) {
		cpu_set(cpu, smp_commenced_mask);
		while (!cpu_isset(cpu, cpu_online_map))
			mb();
		if (!cpu_isset(cpu, cpu_online_map)) {
			ret = -ENODEV;
		} else {
			smp_synchronize_one_tick(cpu);
		}
	}
	return ret;
}

void __init smp_cpus_done(unsigned int max_cpus)
{
	unsigned long bogosum = 0;
	int i;

	for (i = 0; i < NR_CPUS; i++) {
		if (cpu_online(i))
			bogosum += cpu_data(i).udelay_val;
	}
	printk("Total of %ld processors activated "
	       "(%lu.%02lu BogoMIPS).\n",
	       (long) num_online_cpus(),
	       bogosum/(500000/HZ),
	       (bogosum/(5000/HZ))%100);

	/* We want to run this with all the other cpus spinning
	 * in the kernel.
	 */
	smp_tune_scheduling();
}

/* This needn't do anything as we do not sleep the cpu
 * inside of the idler task, so an interrupt is not needed
 * to get a clean fast response.
 *
 * XXX Reverify this assumption... -DaveM
 *
 * Addendum: We do want it to do something for the signal
 *           delivery case, we detect that by just seeing
 *           if we are trying to send this to an idler or not.
 */
void smp_send_reschedule(int cpu)
{
	if (cpu_data(cpu).idle_volume == 0)
		smp_receive_signal(cpu);
}

/* This is a nop because we capture all other cpus
 * anyways when making the PROM active.
 */
void smp_send_stop(void)
{
}