/*
 * SMP Support
 *
 * Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
 * Copyright (C) 1999, 2001, 2003 David Mosberger-Tang <davidm@hpl.hp.com>
 *
 * Lots of stuff stolen from arch/alpha/kernel/smp.c
 *
 * 01/05/16 Rohit Seth <rohit.seth@intel.com>  IA64-SMP functions. Reorganized
 * the existing code (on the lines of x86 port).
 * 00/09/11 David Mosberger <davidm@hpl.hp.com> Do loops_per_jiffy
 * calibration on each CPU.
 * 00/08/23 Asit Mallick <asit.k.mallick@intel.com> fixed logical processor id
 * 00/03/31 Rohit Seth <rohit.seth@intel.com>   Fixes for Bootstrap Processor
 * & cpu_online_map now gets done here (instead of setup.c)
 * 99/10/05 davidm      Update to bring it in sync with new command-line processing
 *  scheme.
 * 10/13/00 Goutham Rao <goutham.rao@intel.com> Updated smp_call_function and
 *              smp_call_function_single to resend IPI on timeouts
 */
#include <linux/module.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/cache.h>
#include <linux/delay.h>
#include <linux/efi.h>
#include <linux/bitops.h>
#include <linux/kexec.h>

#include <linux/atomic.h>
#include <asm/current.h>
#include <asm/delay.h>
#include <asm/machvec.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/page.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/ptrace.h>
#include <asm/sal.h>
#include <asm/tlbflush.h>
#include <asm/unistd.h>
#include <asm/mca.h>

/*
 * Note: alignment of 4 entries/cacheline was empirically determined
 * to be a good tradeoff between hot cachelines & spreading the array
 * across too many cacheline.
 */
static struct local_tlb_flush_counts {
        unsigned int count;
} __attribute__((__aligned__(32))) local_tlb_flush_counts[NR_CPUS];

static DEFINE_PER_CPU_SHARED_ALIGNED(unsigned short [NR_CPUS],
                                     shadow_flush_counts);

#define IPI_CALL_FUNC           0
#define IPI_CPU_STOP            1
#define IPI_CALL_FUNC_SINGLE    2
#define IPI_KDUMP_CPU_STOP      3

/* This needs to be cacheline aligned because it is written to by *other* CPUs.  */
static DEFINE_PER_CPU_SHARED_ALIGNED(unsigned long, ipi_operation);

extern void cpu_halt (void);

static void
stop_this_cpu(void)
{
        /*
         * Remove this CPU:
         */
        set_cpu_online(smp_processor_id(), false);
        max_xtp();
        local_irq_disable();
        cpu_halt();
}

void
cpu_die(void)
{
        max_xtp();
        local_irq_disable();
        cpu_halt();
        /* Should never be here */
        BUG();
        for (;;);
}

irqreturn_t
handle_IPI (int irq, void *dev_id)
{
        int this_cpu = get_cpu();
        unsigned long *pending_ipis = &__ia64_per_cpu_var(ipi_operation);
        unsigned long ops;

        mb();   /* Order interrupt and bit testing. */
        while ((ops = xchg(pending_ipis, 0)) != 0) {
                mb();   /* Order bit clearing and data access. */
                do {
                        unsigned long which;

                        which = ffz(~ops);
                        ops &= ~(1 << which);

                        switch (which) {
                        case IPI_CPU_STOP:
                                stop_this_cpu();
                                break;
                        case IPI_CALL_FUNC:
                                generic_smp_call_function_interrupt();
                                break;
                        case IPI_CALL_FUNC_SINGLE:
                                generic_smp_call_function_single_interrupt();
                                break;
#ifdef CONFIG_KEXEC
                        case IPI_KDUMP_CPU_STOP:
                                unw_init_running(kdump_cpu_freeze, NULL);
                                break;
#endif
                        default:
                                printk(KERN_CRIT "Unknown IPI on CPU %d: %lu\n",
                                                this_cpu, which);
                                break;
                        }
                } while (ops);
                mb();   /* Order data access and bit testing. */
        }
        put_cpu();
        return IRQ_HANDLED;
}



/*
 * Called with preemption disabled.
 */
static inline void
send_IPI_single (int dest_cpu, int op)
{
        set_bit(op, &per_cpu(ipi_operation, dest_cpu));
        platform_send_ipi(dest_cpu, IA64_IPI_VECTOR, IA64_IPI_DM_INT, 0);
}

/*
 * Called with preemption disabled.
 */
static inline void
send_IPI_allbutself (int op)
{
        unsigned int i;

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

/*
 * Called with preemption disabled.
 */
static inline void
send_IPI_mask(const struct cpumask *mask, int op)
{
        unsigned int cpu;

        for_each_cpu(cpu, mask) {
                        send_IPI_single(cpu, op);
        }
}

/*
 * Called with preemption disabled.
 */
static inline void
send_IPI_all (int op)
{
        int i;

        for_each_online_cpu(i) {
                send_IPI_single(i, op);
        }
}

/*
 * Called with preemption disabled.
 */
static inline void
send_IPI_self (int op)
{
        send_IPI_single(smp_processor_id(), op);
}

#ifdef CONFIG_KEXEC
void
kdump_smp_send_stop(void)
{
        send_IPI_allbutself(IPI_KDUMP_CPU_STOP);
}

void
kdump_smp_send_init(void)
{
        unsigned int cpu, self_cpu;
        self_cpu = smp_processor_id();
        for_each_online_cpu(cpu) {
                if (cpu != self_cpu) {
                        if(kdump_status[cpu] == 0)
                                platform_send_ipi(cpu, 0, IA64_IPI_DM_INIT, 0);
                }
        }
}
#endif
/*
 * Called with preemption disabled.
 */
void
smp_send_reschedule (int cpu)
{
        platform_send_ipi(cpu, IA64_IPI_RESCHEDULE, IA64_IPI_DM_INT, 0);
}
EXPORT_SYMBOL_GPL(smp_send_reschedule);

/*
 * Called with preemption disabled.
 */
static void
smp_send_local_flush_tlb (int cpu)
{
        platform_send_ipi(cpu, IA64_IPI_LOCAL_TLB_FLUSH, IA64_IPI_DM_INT, 0);
}

void
smp_local_flush_tlb(void)
{
        /*
         * Use atomic ops. Otherwise, the load/increment/store sequence from
         * a "++" operation can have the line stolen between the load & store.
         * The overhead of the atomic op in negligible in this case & offers
         * significant benefit for the brief periods where lots of cpus
         * are simultaneously flushing TLBs.
         */
        ia64_fetchadd(1, &local_tlb_flush_counts[smp_processor_id()].count, acq);
        local_flush_tlb_all();
}

#define FLUSH_DELAY     5 /* Usec backoff to eliminate excessive cacheline bouncing */

void
smp_flush_tlb_cpumask(cpumask_t xcpumask)
{
        unsigned short *counts = __ia64_per_cpu_var(shadow_flush_counts);
        cpumask_t cpumask = xcpumask;
        int mycpu, cpu, flush_mycpu = 0;

        preempt_disable();
        mycpu = smp_processor_id();

        for_each_cpu(cpu, &cpumask)
                counts[cpu] = local_tlb_flush_counts[cpu].count & 0xffff;

        mb();
        for_each_cpu(cpu, &cpumask) {
                if (cpu == mycpu)
                        flush_mycpu = 1;
                else
                        smp_send_local_flush_tlb(cpu);
        }

        if (flush_mycpu)
                smp_local_flush_tlb();

        for_each_cpu(cpu, &cpumask)
                while(counts[cpu] == (local_tlb_flush_counts[cpu].count & 0xffff))
                        udelay(FLUSH_DELAY);

        preempt_enable();
}

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

void
smp_flush_tlb_mm (struct mm_struct *mm)
{
        cpumask_var_t cpus;
        preempt_disable();
        /* this happens for the common case of a single-threaded fork():  */
        if (likely(mm == current->active_mm && atomic_read(&mm->mm_users) == 1))
        {
                local_finish_flush_tlb_mm(mm);
                preempt_enable();
                return;
        }
        if (!alloc_cpumask_var(&cpus, GFP_ATOMIC)) {
                smp_call_function((void (*)(void *))local_finish_flush_tlb_mm,
                        mm, 1);
        } else {
                cpumask_copy(cpus, mm_cpumask(mm));
                smp_call_function_many(cpus,
                        (void (*)(void *))local_finish_flush_tlb_mm, mm, 1);
                free_cpumask_var(cpus);
        }
        local_irq_disable();
        local_finish_flush_tlb_mm(mm);
        local_irq_enable();
        preempt_enable();
}

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

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

/*
 * this function calls the 'stop' function on all other CPUs in the system.
 */
void
smp_send_stop (void)
{
        send_IPI_allbutself(IPI_CPU_STOP);
}

int
setup_profiling_timer (unsigned int multiplier)
{
        return -EINVAL;
}