/*
** SMP Support
**
** Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
** Copyright (C) 1999 David Mosberger-Tang <davidm@hpl.hp.com>
** Copyright (C) 2001 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 alot from their work.
** -grant (1/12/2001)
**
**	This program is free software; you can redistribute it and/or modify
**	it under the terms of the GNU General Public License as published by
**      the Free Software Foundation; either version 2 of the License, or
**      (at your option) any later version.
*/
#define __KERNEL_SYSCALLS__
#undef ENTRY_SYS_CPUS	/* syscall support for iCOD-like functionality */

#include <linux/autoconf.h>

#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/slab.h>

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/smp.h>
#include <linux/kernel_stat.h>
#include <linux/mm.h>
#include <linux/delay.h>

#include <asm/system.h>
#include <asm/atomic.h>
#include <asm/bitops.h>
#include <asm/current.h>
#include <asm/delay.h>
#include <asm/pgalloc.h>	/* for flush_tlb_all() proto/macro */

#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/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/processor.h>
#include <asm/ptrace.h>
#include <asm/unistd.h>
#include <asm/cacheflush.h>

#define kDEBUG 0

spinlock_t pa_dbit_lock = SPIN_LOCK_UNLOCKED;

spinlock_t smp_lock = SPIN_LOCK_UNLOCKED;

volatile struct task_struct *smp_init_current_idle_task;

static volatile int smp_commenced = 0;   /* Set when the idlers are all forked */
static volatile int cpu_now_booting = 0;      /* track which CPU is booting */
volatile unsigned long cpu_online_map = 0;   /* Bitmap of online CPUs */
#define IS_LOGGED_IN(cpunum) (test_bit(cpunum, (atomic_t *)&cpu_online_map))

int smp_num_cpus = 1;
int smp_threads_ready = 0;
unsigned long cache_decay_ticks;
static int max_cpus = -1;			     /* Command line */
unsigned long cpu_present_mask;

struct smp_call_struct {
	void (*func) (void *info);
	void *info;
	long wait;
	atomic_t unstarted_count;
	atomic_t unfinished_count;
};
static volatile struct smp_call_struct *smp_call_function_data;

enum ipi_message_type {
	IPI_NOP=0,
	IPI_RESCHEDULE=1,
	IPI_CALL_FUNC,
	IPI_CPU_START,
	IPI_CPU_STOP,
	IPI_CPU_TEST
};


/********** 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)
{

	/* If CPU is present ... */
#ifdef ENTRY_SYS_CPUS
	/* *and* running (not stopped) ... */
#error iCOD support wants state checked here.
#endif

#error verify IRQ_OFFSET(IPI_IRQ) is ipi_interrupt() in new IRQ region

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

	return;
}
#endif


/*
** Yoink this CPU from the runnable list... 
**
*/
static void
halt_processor(void) 
{
#ifdef ENTRY_SYS_CPUS
#error halt_processor() needs rework
/*
** o migrate I/O interrupts off this CPU.
** o leave IPI enabled - __cli() will disable IPI.
** o leave CPU in online map - just change the state
*/
	cpu_data[this_cpu].state = STATE_STOPPED;
	mark_bh(IPI_BH);
#else
	/* REVISIT : redirect I/O Interrupts to another CPU? */
	/* REVISIT : does PM *know* this CPU isn't available? */
	clear_bit(smp_processor_id(), (void *)&cpu_online_map);
	local_irq_disable();
	for (;;)
		;
#endif
}


void
ipi_interrupt(int irq, void *dev_id, struct pt_regs *regs) 
{
	int this_cpu = smp_processor_id();
	struct cpuinfo_parisc *p = &cpu_data[this_cpu];
	unsigned long ops;
	unsigned long flags;

	/* Count this now; we may make a call that never returns. */
	p->ipi_count++;

	mb();	/* Order interrupt and bit testing. */

	for (;;) {
		spin_lock_irqsave(&(p->lock),flags);
		ops = p->pending_ipi;
		p->pending_ipi = 0;
		spin_unlock_irqrestore(&(p->lock),flags);

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

		if (!ops)
		    break;

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

			switch (which) {
			case IPI_RESCHEDULE:
#if (kDEBUG>=100)
				printk(KERN_DEBUG "CPU%d IPI_RESCHEDULE\n",this_cpu);
#endif /* kDEBUG */
				ops &= ~(1 << IPI_RESCHEDULE);
				/*
				 * Reschedule callback.  Everything to be
				 * done is done by the interrupt return path.
				 */
				break;

			case IPI_CALL_FUNC:
#if (kDEBUG>=100)
				printk(KERN_DEBUG "CPU%d IPI_CALL_FUNC\n",this_cpu);
#endif /* kDEBUG */
				ops &= ~(1 << IPI_CALL_FUNC);
				{
					volatile struct smp_call_struct *data;
					void (*func)(void *info);
					void *info;
					int wait;

					data = smp_call_function_data;
					func = data->func;
					info = data->info;
					wait = data->wait;

					mb();
					atomic_dec ((atomic_t *)&data->unstarted_count);

					/* At this point, *data can't
					 * be relied upon.
					 */

					(*func)(info);

					/* Notify the sending CPU that the
					 * task is done.
					 */
					mb();
					if (wait)
						atomic_dec ((atomic_t *)&data->unfinished_count);
				}
				break;

			case IPI_CPU_START:
#if (kDEBUG>=100)
				printk(KERN_DEBUG "CPU%d IPI_CPU_START\n",this_cpu);
#endif /* kDEBUG */
				ops &= ~(1 << IPI_CPU_START);
#ifdef ENTRY_SYS_CPUS
				p->state = STATE_RUNNING;
#endif
				break;

			case IPI_CPU_STOP:
#if (kDEBUG>=100)
				printk(KERN_DEBUG "CPU%d IPI_CPU_STOP\n",this_cpu);
#endif /* kDEBUG */
				ops &= ~(1 << IPI_CPU_STOP);
#ifdef ENTRY_SYS_CPUS
#else
				halt_processor();
#endif
				break;

			case IPI_CPU_TEST:
#if (kDEBUG>=100)
				printk(KERN_DEBUG "CPU%d is alive!\n",this_cpu);
#endif /* kDEBUG */
				ops &= ~(1 << IPI_CPU_TEST);
				break;

			default:
				printk(KERN_CRIT "Unknown IPI num on CPU%d: %lu\n",
					this_cpu, which);
				ops &= ~(1 << which);
				return;
			} /* Switch */
		} /* while (ops) */
	}
	return;
}


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

	spin_lock_irqsave(&(p->lock),flags);
	p->pending_ipi |= 1 << op;
	__raw_writel(IRQ_OFFSET(IPI_IRQ), cpu_data[cpu].hpa);
	spin_unlock_irqrestore(&(p->lock),flags);
}


static inline void
send_IPI_single(int dest_cpu, enum ipi_message_type op)
{
	if (dest_cpu == NO_PROC_ID) {
		BUG();
		return;
	}

	ipi_send(dest_cpu, op);
}

static inline void
send_IPI_allbutself(enum ipi_message_type op)
{
	int i;
	
	for (i = 0; i < smp_num_cpus; i++) {
		if (i != smp_processor_id())
			send_IPI_single(i, op);
	}
}

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

static inline void
smp_send_start(void)	{ send_IPI_allbutself(IPI_CPU_START); }

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


/**
 * Run a function on all other CPUs.
 *  <func>	The function to run. This must be fast and non-blocking.
 *  <info>	An arbitrary pointer to pass to the function.
 *  <retry>	If true, keep retrying until ready.
 *  <wait>	If true, wait until function has completed on other CPUs.
 *  [RETURNS]   0 on success, else a negative status code.
 *
 * Does not return until remote CPUs are nearly ready to execute <func>
 * or have executed.
 */

int
smp_call_function (void (*func) (void *info), void *info, int retry, int wait)
{
	struct smp_call_struct data;
	long timeout;
	static spinlock_t lock = SPIN_LOCK_UNLOCKED;
	
	data.func = func;
	data.info = info;
	data.wait = wait;
	atomic_set(&data.unstarted_count, smp_num_cpus - 1);
	atomic_set(&data.unfinished_count, smp_num_cpus - 1);

	if (retry) {
		spin_lock (&lock);
		while (smp_call_function_data != 0)
			barrier();
	}
	else {
		spin_lock (&lock);
		if (smp_call_function_data) {
			spin_unlock (&lock);
			return -EBUSY;
		}
	}

	smp_call_function_data = &data;
	spin_unlock (&lock);
	
	/*  Send a message to all other CPUs and wait for them to respond  */
	send_IPI_allbutself(IPI_CALL_FUNC);

	/*  Wait for response  */
	timeout = jiffies + HZ;
	while ( (atomic_read (&data.unstarted_count) > 0) &&
		time_before (jiffies, timeout) )
		barrier ();

	/* We either got one or timed out. Release the lock */

	mb();
	smp_call_function_data = NULL;
	if (atomic_read (&data.unstarted_count) > 0) {
		printk(KERN_CRIT "SMP CALL FUNCTION TIMED OUT! (cpu=%d)\n",
		      smp_processor_id());
		return -ETIMEDOUT;
	}

	while (wait && atomic_read (&data.unfinished_count) > 0)
			barrier ();

	return 0;
}



/*
 *	Setup routine for controlling SMP activation
 *
 *	Command-line option of "nosmp" or "maxcpus=0" will disable SMP
 *	activation entirely (the MPS table probe still happens, though).
 *
 *	Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
 *	greater than 0, limits the maximum number of CPUs activated in
 *	SMP mode to <NUM>.
 */

static int __init nosmp(char *str)
{
	max_cpus = 0;
	return 1;
}

__setup("nosmp", nosmp);

static int __init maxcpus(char *str)
{
	get_option(&str, &max_cpus);
	return 1;
}

__setup("maxcpus=", maxcpus);

/*
 * Flush all other CPU's tlb and then mine.  Do this with on_each_cpu()
 * as we want to ensure all TLB's flushed before proceeding.
 */

extern void flush_tlb_all_local(void);

void
smp_flush_tlb_all(void)
{
	on_each_cpu((void (*)(void *))flush_tlb_all_local, NULL, 1, 1);
}


void 
smp_do_timer(struct pt_regs *regs)
{
	int cpu = smp_processor_id();
	struct cpuinfo_parisc *data = &cpu_data[cpu];

        if (!--data->prof_counter) {
		data->prof_counter = data->prof_multiplier;
		update_process_times(user_mode(regs));
	}
}

/*
 * Called by secondaries to update state and initialize CPU registers.
 */
static void __init
smp_cpu_init(int cpunum)
{
	extern int init_per_cpu(int);  /* arch/parisc/kernel/setup.c */
	extern void init_IRQ(void);    /* arch/parisc/kernel/irq.c */

	/* Set modes and Enable floating point coprocessor */
	(void) init_per_cpu(cpunum);

	disable_sr_hashing();

	mb();

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

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

	/* Initialise the idle task for this CPU */
	atomic_inc(&init_mm.mm_count);
	current->active_mm = &init_mm;
	if(current->mm)
		BUG();
	enter_lazy_tlb(&init_mm, current, cpunum);

	init_IRQ();   /* make sure no IRQ's are enabled or pending */
}


/*
 * 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(void)
{
	extern void cpu_idle(void);	/* arch/parisc/kernel/process.c */
	int slave_id = cpu_now_booting;
#if 0
	void *istack;
#endif

	smp_cpu_init(slave_id);

#if 0	/* NOT WORKING YET - see entry.S */
	istack = (void *)__get_free_pages(GFP_KERNEL,ISTACK_ORDER);
	if (istack == NULL) {
	    printk(KERN_CRIT "Failed to allocate interrupt stack for cpu %d\n",slave_id);
	    BUG();
	}
	mtctl(istack,31);
#endif

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

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

	/* Slaves wait here until Big Poppa daddy say "jump" */
	mb();	/* PARANOID */
	while (!smp_commenced) ;
	mb();	/* PARANOID */

	cpu_idle();      /* Wait for timer to schedule some work */

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

/*
 * Create the idle task for a new Slave CPU.  DO NOT use kernel_thread()
 * because that could end up calling schedule(). If it did, the new idle
 * task could get scheduled before we had a chance to remove it from the
 * run-queue...
 */
static struct task_struct *fork_by_hand(void)
{
	struct pt_regs regs;  

	/*
	 * don't care about the regs settings since
	 * we'll never reschedule the forked task.
	 */
	return do_fork(CLONE_VM|CLONE_IDLETASK, 0, &regs, 0, NULL, NULL);
}


/*
 * Bring one cpu online.
 */
static int smp_boot_one_cpu(int cpuid, int cpunum)
{
	struct task_struct *idle;
	long timeout;

	/* 
	 * Create an idle task for this CPU.  Note the address wed* give 
	 * to kernel_thread is irrelevant -- it's going to start
	 * where OS_BOOT_RENDEVZ vector in SAL says to start.  But
	 * this gets all the other task-y sort of data structures set
	 * up like we wish.   We need to pull the just created idle task 
	 * off the run queue and stuff it into the init_tasks[] array.  
	 * Sheesh . . .
	 */

	if ((idle = fork_by_hand()) == 0) 
		panic("SMP: fork failed for CPU:%d", cpuid);

	init_idle(idle, cpunum);
	unhash_process(idle);
	idle->thread_info->cpu = cpunum;

	/* Let _start know what logical CPU we're booting
	** (offset into init_tasks[],cpu_data[])
	*/
	cpu_now_booting = cpunum;

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

	/*
	** This gets PDC to release the CPU from a very tight loop.
	** See MEM_RENDEZ comments in head.S.
	*/
	__raw_writel(IRQ_OFFSET(TIMER_IRQ), cpu_data[cpunum].hpa);
	mb();

	/* 
	 * OK, wait a bit for that CPU to finish staggering about. 
	 * Slave will set a bit when it reaches smp_cpu_init() and then
	 * wait for smp_commenced to be 1.
	 * Once we see the bit change, we can move on.
	 */
	for (timeout = 0; timeout < 10000; timeout++) {
		if(IS_LOGGED_IN(cpunum)) {
			/* Which implies Slave has started up */
			cpu_now_booting = 0;
			smp_init_current_idle_task = NULL;
			goto alive ;
		}
		udelay(100);
		barrier();
	}

	put_task_struct(idle);
	idle = NULL;

	printk(KERN_CRIT "SMP: CPU:%d is stuck.\n", cpuid);
	return -1;

alive:
	/* Remember the Slave data */
#if (kDEBUG>=100)
	printk(KERN_DEBUG "SMP: CPU:%d (num %d) came alive after %ld _us\n",
		cpuid,  cpunum, timeout * 100);
#endif /* kDEBUG */
#ifdef ENTRY_SYS_CPUS
	cpu_data[cpunum].state = STATE_RUNNING;
#endif
	return 0;
}




/*
** inventory.c:do_inventory() has already 'discovered' the additional CPU's.
** We are ready to wrest them from PDC's control now.
** Called by smp_init bring all the secondaries online and hold them.  
**
** o Setup of the IPI irq handler is done in irq.c.
** o MEM_RENDEZ is initialzed in head.S:stext()
**
*/
void __init smp_boot_cpus(void)
{
	int i, cpu_count = 1;
	unsigned long bogosum = loops_per_jiffy; /* Count Monarch */

	/* REVISIT - assumes first CPU reported by PAT PDC is BSP */
	int bootstrap_processor=cpu_data[0].cpuid;	/* CPU ID of BSP */

	/* Setup BSP mappings */
	printk(KERN_DEBUG "SMP: bootstrap CPU ID is %d\n",bootstrap_processor);
	init_task.thread_info->cpu = bootstrap_processor; 
	current->thread_info->cpu = bootstrap_processor;
	cpu_online_map = 1 << bootstrap_processor; /* Mark Boostrap processor as present */
	current->active_mm = &init_mm;

#ifdef ENTRY_SYS_CPUS
	cpu_data[0].state = STATE_RUNNING;
#endif
	cpu_present_mask = 1UL << bootstrap_processor;

	/* Nothing to do when told not to.  */
	if (max_cpus == 0) {
		printk(KERN_INFO "SMP mode deactivated.\n");
		return;
	}

	if (max_cpus != -1) 
		printk(KERN_INFO "Limiting CPUs to %d\n", max_cpus);

	/* We found more than one CPU.... */
	if (boot_cpu_data.cpu_count > 1) {

		for (i = 0; i < NR_CPUS; i++) {
			if (cpu_data[i].cpuid == NO_PROC_ID || 
			    cpu_data[i].cpuid == bootstrap_processor)
				continue;

			if (smp_boot_one_cpu(cpu_data[i].cpuid, cpu_count) < 0)
				continue;

			bogosum += loops_per_jiffy;
			cpu_count++; /* Count good CPUs only... */
			
			cpu_present_mask |= 1UL << i;
			
			/* Bail when we've started as many CPUS as told to */
			if (cpu_count == max_cpus)
				break;
		}
	}
	if (cpu_count == 1) {
		printk(KERN_INFO "SMP: Bootstrap processor only.\n");
	}

	/*
	 * FIXME very rough.
	 */
	cache_decay_ticks = HZ/100;

	printk(KERN_INFO "SMP: Total %d of %d processors activated "
	       "(%lu.%02lu BogoMIPS noticed) (Present Mask: %lu).\n",
	       cpu_count, boot_cpu_data.cpu_count, (bogosum + 25) / 5000,
	       ((bogosum + 25) / 50) % 100, cpu_present_mask);

	smp_num_cpus = cpu_count;
#ifdef PER_CPU_IRQ_REGION
	ipi_init();
#endif
	return;
}

/* 
 * Called from main.c by Monarch Processor.
 * After this, any CPU can schedule any task.
 */
void smp_commence(void)
{
	smp_commenced = 1;
	mb();
	return;
}

/*
 * XXX FIXME : do nothing
 */
void smp_cpus_done(unsigned int cpu_max)
{
	smp_threads_ready = 1;
}

void __init smp_prepare_cpus(unsigned int max_cpus)
{
	smp_boot_cpus();
}

void __devinit smp_prepare_boot_cpu(void)
{
	set_bit(smp_processor_id(), &cpu_online_map);
	set_bit(smp_processor_id(), &cpu_present_mask);
}

int __devinit __cpu_up(unsigned int cpu)
{
	return cpu_online(cpu) ? 0 : -ENOSYS;
}



#ifdef ENTRY_SYS_CPUS
/* Code goes along with:
**    entry.s:        ENTRY_NAME(sys_cpus)   / * 215, for cpu stat * /
*/
int sys_cpus(int argc, char **argv)
{
	int i,j=0;
	extern int current_pid(int cpu);

	if( argc > 2 ) {
		printk("sys_cpus:Only one argument supported\n");
		return (-1);
	}
	if ( argc == 1 ){
	
#ifdef DUMP_MORE_STATE
		for(i=0; i<NR_CPUS; i++) {
			int cpus_per_line = 4;
			if(IS_LOGGED_IN(i)) {
				if (j++ % cpus_per_line)
					printk(" %3d",i);
				else
					printk("\n %3d",i);
			}
		}
		printk("\n"); 
#else
	    	printk("\n 0\n"); 
#endif
	} else if((argc==2) && !(strcmp(argv[1],"-l"))) {
		printk("\nCPUSTATE  TASK CPUNUM CPUID HARDCPU(HPA)\n");
#ifdef DUMP_MORE_STATE
		for(i=0;i<NR_CPUS;i++) {
			if (!IS_LOGGED_IN(i))
				continue;
			if (cpu_data[i].cpuid != NO_PROC_ID) {
				switch(cpu_data[i].state) {
					case STATE_RENDEZVOUS:
						printk("RENDEZVS ");
						break;
					case STATE_RUNNING:
						printk((current_pid(i)!=0) ? "RUNNING  " : "IDLING   ");
						break;
					case STATE_STOPPED:
						printk("STOPPED  ");
						break;
					case STATE_HALTED:
						printk("HALTED   ");
						break;
					default:
						printk("%08x?", cpu_data[i].state);
						break;
				}
				if(IS_LOGGED_IN(i)) {
					printk(" %4d",current_pid(i));
				}	
				printk(" %6d",cpu_number_map(i));
				printk(" %5d",i);
				printk(" 0x%lx\n",cpu_data[i].hpa);
			}	
		}
#else
		printk("\n%s  %4d      0     0 --------",
			(current->pid)?"RUNNING ": "IDLING  ",current->pid); 
#endif
	} else if ((argc==2) && !(strcmp(argv[1],"-s"))) { 
#ifdef DUMP_MORE_STATE
     		printk("\nCPUSTATE   CPUID\n");
		for (i=0;i<NR_CPUS;i++) {
			if (!IS_LOGGED_IN(i))
				continue;
			if (cpu_data[i].cpuid != NO_PROC_ID) {
				switch(cpu_data[i].state) {
					case STATE_RENDEZVOUS:
						printk("RENDEZVS");break;
					case STATE_RUNNING:
						printk((current_pid(i)!=0) ? "RUNNING " : "IDLING");
						break;
					case STATE_STOPPED:
						printk("STOPPED ");break;
					case STATE_HALTED:
						printk("HALTED  ");break;
					default:
				}
				printk("  %5d\n",i);
			}	
		}
#else
		printk("\n%s    CPU0",(current->pid==0)?"RUNNING ":"IDLING  "); 
#endif
	} else {
		printk("sys_cpus:Unknown request\n");
		return (-1);
	}
	return 0;
}
#endif /* ENTRY_SYS_CPUS */

#ifdef CONFIG_PROC_FS
int __init
setup_profiling_timer(unsigned int multiplier)
{
	return -EINVAL;
}
#endif
