/*
 *  linux/arch/arm/kernel/smp.c
 *
 *  Copyright (C) 2002 ARM Limited, All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/cache.h>
#include <linux/profile.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/err.h>
#include <linux/cpu.h>
#include <linux/smp.h>
#include <linux/seq_file.h>
#include <linux/irq.h>
#include <linux/percpu.h>
#include <linux/clockchips.h>

#include <asm/atomic.h>
#include <asm/cacheflush.h>
#include <asm/cpu.h>
#include <asm/cputype.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/processor.h>
#include <asm/tlbflush.h>
#include <asm/ptrace.h>
#include <asm/localtimer.h>
#include <asm/smp_plat.h>

/*
 * as from 2.5, kernels no longer have an init_tasks structure
 * so we need some other way of telling a new secondary core
 * where to place its SVC stack
 */
struct secondary_data secondary_data;

/*
 * structures for inter-processor calls
 * - A collection of single bit ipi messages.
 */
struct ipi_data {
        spinlock_t lock;
        unsigned long ipi_count;
        unsigned long bits;
};

static DEFINE_PER_CPU(struct ipi_data, ipi_data) = {
        .lock   = SPIN_LOCK_UNLOCKED,
};

enum ipi_msg_type {
        IPI_TIMER,
        IPI_RESCHEDULE,
        IPI_CALL_FUNC,
        IPI_CALL_FUNC_SINGLE,
        IPI_CPU_STOP,
};

int __cpuinit __cpu_up(unsigned int cpu)
{
        struct cpuinfo_arm *ci = &per_cpu(cpu_data, cpu);
        struct task_struct *idle = ci->idle;
        pgd_t *pgd;
        pmd_t *pmd;
        int ret;

        /*
         * Spawn a new process manually, if not already done.
         * Grab a pointer to its task struct so we can mess with it
         */
        if (!idle) {
                idle = fork_idle(cpu);
                if (IS_ERR(idle)) {
                        printk(KERN_ERR "CPU%u: fork() failed\n", cpu);
                        return PTR_ERR(idle);
                }
                ci->idle = idle;
        }

        /*
         * Allocate initial page tables to allow the new CPU to
         * enable the MMU safely.  This essentially means a set
         * of our "standard" page tables, with the addition of
         * a 1:1 mapping for the physical address of the kernel.
         */
        pgd = pgd_alloc(&init_mm);
        pmd = pmd_offset(pgd + pgd_index(PHYS_OFFSET), PHYS_OFFSET);
        *pmd = __pmd((PHYS_OFFSET & PGDIR_MASK) |
                     PMD_TYPE_SECT | PMD_SECT_AP_WRITE);
        flush_pmd_entry(pmd);

        /*
         * We need to tell the secondary core where to find
         * its stack and the page tables.
         */
        secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
        secondary_data.pgdir = virt_to_phys(pgd);
        wmb();

        /*
         * Now bring the CPU into our world.
         */
        ret = boot_secondary(cpu, idle);
        if (ret == 0) {
                unsigned long timeout;

                /*
                 * CPU was successfully started, wait for it
                 * to come online or time out.
                 */
                timeout = jiffies + HZ;
                while (time_before(jiffies, timeout)) {
                        if (cpu_online(cpu))
                                break;

                        udelay(10);
                        barrier();
                }

                if (!cpu_online(cpu))
                        ret = -EIO;
        }

        secondary_data.stack = NULL;
        secondary_data.pgdir = 0;

        *pmd = __pmd(0);
        clean_pmd_entry(pmd);
        pgd_free(&init_mm, pgd);

        if (ret) {
                printk(KERN_CRIT "CPU%u: processor failed to boot\n", cpu);

                /*
                 * FIXME: We need to clean up the new idle thread. --rmk
                 */
        }

        return ret;
}

#ifdef CONFIG_HOTPLUG_CPU
/*
 * __cpu_disable runs on the processor to be shutdown.
 */
int __cpu_disable(void)
{
        unsigned int cpu = smp_processor_id();
        struct task_struct *p;
        int ret;

        ret = mach_cpu_disable(cpu);
        if (ret)
                return ret;

        /*
         * 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);

        /*
         * OK - migrate IRQs away from this CPU
         */
        migrate_irqs();

        /*
         * Stop the local timer for this CPU.
         */
        local_timer_stop();

        /*
         * Flush user cache and TLB mappings, and then remove this CPU
         * from the vm mask set of all processes.
         */
        flush_cache_all();
        local_flush_tlb_all();

        read_lock(&tasklist_lock);
        for_each_process(p) {
                if (p->mm)
                        cpumask_clear_cpu(cpu, mm_cpumask(p->mm));
        }
        read_unlock(&tasklist_lock);

        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)
{
        if (!platform_cpu_kill(cpu))
                printk("CPU%u: unable to kill\n", cpu);
}

/*
 * Called from the idle thread for the CPU which has been shutdown.
 *
 * Note that we disable IRQs here, but do not re-enable them
 * before returning to the caller. This is also the behaviour
 * of the other hotplug-cpu capable cores, so presumably coming
 * out of idle fixes this.
 */
void __ref cpu_die(void)
{
        unsigned int cpu = smp_processor_id();

        local_irq_disable();
        idle_task_exit();

        /*
         * actual CPU shutdown procedure is at least platform (if not
         * CPU) specific
         */
        platform_cpu_die(cpu);

        /*
         * Do not return to the idle loop - jump back to the secondary
         * cpu initialisation.  There's some initialisation which needs
         * to be repeated to undo the effects of taking the CPU offline.
         */
        __asm__("mov    sp, %0\n"
        "       b       secondary_start_kernel"
                :
                : "r" (task_stack_page(current) + THREAD_SIZE - 8));
}
#endif /* CONFIG_HOTPLUG_CPU */

/*
 * This is the secondary CPU boot entry.  We're using this CPUs
 * idle thread stack, but a set of temporary page tables.
 */
asmlinkage void __cpuinit secondary_start_kernel(void)
{
        struct mm_struct *mm = &init_mm;
        unsigned int cpu = smp_processor_id();

        printk("CPU%u: Booted secondary processor\n", cpu);

        /*
         * All kernel threads share the same mm context; grab a
         * reference and switch to it.
         */
        atomic_inc(&mm->mm_users);
        atomic_inc(&mm->mm_count);
        current->active_mm = mm;
        cpumask_set_cpu(cpu, mm_cpumask(mm));
        cpu_switch_mm(mm->pgd, mm);
        enter_lazy_tlb(mm, current);
        local_flush_tlb_all();

        cpu_init();
        preempt_disable();

        /*
         * Give the platform a chance to do its own initialisation.
         */
        platform_secondary_init(cpu);

        /*
         * Enable local interrupts.
         */
        notify_cpu_starting(cpu);
        local_irq_enable();
        local_fiq_enable();

        /*
         * Setup the percpu timer for this CPU.
         */
        percpu_timer_setup();

        calibrate_delay();

        smp_store_cpu_info(cpu);

        /*
         * OK, now it's safe to let the boot CPU continue
         */
        set_cpu_online(cpu, true);

        /*
         * OK, it's off to the idle thread for us
         */
        cpu_idle();
}

/*
 * Called by both boot and secondaries to move global data into
 * per-processor storage.
 */
void __cpuinit smp_store_cpu_info(unsigned int cpuid)
{
        struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);

        cpu_info->loops_per_jiffy = loops_per_jiffy;
}

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

        for_each_online_cpu(cpu)
                bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;

        printk(KERN_INFO "SMP: Total of %d processors activated "
               "(%lu.%02lu BogoMIPS).\n",
               num_online_cpus(),
               bogosum / (500000/HZ),
               (bogosum / (5000/HZ)) % 100);
}

void __init smp_prepare_boot_cpu(void)
{
        unsigned int cpu = smp_processor_id();

        per_cpu(cpu_data, cpu).idle = current;
}

static void send_ipi_message(const struct cpumask *mask, enum ipi_msg_type msg)
{
        unsigned long flags;
        unsigned int cpu;

        local_irq_save(flags);

        for_each_cpu(cpu, mask) {
                struct ipi_data *ipi = &per_cpu(ipi_data, cpu);

                spin_lock(&ipi->lock);
                ipi->bits |= 1 << msg;
                spin_unlock(&ipi->lock);
        }

        /*
         * Call the platform specific cross-CPU call function.
         */
        smp_cross_call(mask);

        local_irq_restore(flags);
}

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

void arch_send_call_function_single_ipi(int cpu)
{
        send_ipi_message(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
}

void show_ipi_list(struct seq_file *p)
{
        unsigned int cpu;

        seq_puts(p, "IPI:");

        for_each_present_cpu(cpu)
                seq_printf(p, " %10lu", per_cpu(ipi_data, cpu).ipi_count);

        seq_putc(p, '\n');
}

void show_local_irqs(struct seq_file *p)
{
        unsigned int cpu;

        seq_printf(p, "LOC: ");

        for_each_present_cpu(cpu)
                seq_printf(p, "%10u ", irq_stat[cpu].local_timer_irqs);

        seq_putc(p, '\n');
}

/*
 * Timer (local or broadcast) support
 */
static DEFINE_PER_CPU(struct clock_event_device, percpu_clockevent);

static void ipi_timer(void)
{
        struct clock_event_device *evt = &__get_cpu_var(percpu_clockevent);
        irq_enter();
        evt->event_handler(evt);
        irq_exit();
}

#ifdef CONFIG_LOCAL_TIMERS
asmlinkage void __exception do_local_timer(struct pt_regs *regs)
{
        struct pt_regs *old_regs = set_irq_regs(regs);
        int cpu = smp_processor_id();

        if (local_timer_ack()) {
                irq_stat[cpu].local_timer_irqs++;
                ipi_timer();
        }

        set_irq_regs(old_regs);
}
#endif

#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
static void smp_timer_broadcast(const struct cpumask *mask)
{
        send_ipi_message(mask, IPI_TIMER);
}

static void broadcast_timer_set_mode(enum clock_event_mode mode,
        struct clock_event_device *evt)
{
}

static void local_timer_setup(struct clock_event_device *evt)
{
        evt->name       = "dummy_timer";
        evt->features   = CLOCK_EVT_FEAT_ONESHOT |
                          CLOCK_EVT_FEAT_PERIODIC |
                          CLOCK_EVT_FEAT_DUMMY;
        evt->rating     = 400;
        evt->mult       = 1;
        evt->set_mode   = broadcast_timer_set_mode;
        evt->broadcast  = smp_timer_broadcast;

        clockevents_register_device(evt);
}
#endif

void __cpuinit percpu_timer_setup(void)
{
        unsigned int cpu = smp_processor_id();
        struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu);

        evt->cpumask = cpumask_of(cpu);

        local_timer_setup(evt);
}

static DEFINE_SPINLOCK(stop_lock);

/*
 * ipi_cpu_stop - handle IPI from smp_send_stop()
 */
static void ipi_cpu_stop(unsigned int cpu)
{
        spin_lock(&stop_lock);
        printk(KERN_CRIT "CPU%u: stopping\n", cpu);
        dump_stack();
        spin_unlock(&stop_lock);

        set_cpu_online(cpu, false);

        local_fiq_disable();
        local_irq_disable();

        while (1)
                cpu_relax();
}

/*
 * Main handler for inter-processor interrupts
 *
 * For ARM, the ipimask now only identifies a single
 * category of IPI (Bit 1 IPIs have been replaced by a
 * different mechanism):
 *
 *  Bit 0 - Inter-processor function call
 */
asmlinkage void __exception do_IPI(struct pt_regs *regs)
{
        unsigned int cpu = smp_processor_id();
        struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
        struct pt_regs *old_regs = set_irq_regs(regs);

        ipi->ipi_count++;

        for (;;) {
                unsigned long msgs;

                spin_lock(&ipi->lock);
                msgs = ipi->bits;
                ipi->bits = 0;
                spin_unlock(&ipi->lock);

                if (!msgs)
                        break;

                do {
                        unsigned nextmsg;

                        nextmsg = msgs & -msgs;
                        msgs &= ~nextmsg;
                        nextmsg = ffz(~nextmsg);

                        switch (nextmsg) {
                        case IPI_TIMER:
                                ipi_timer();
                                break;

                        case IPI_RESCHEDULE:
                                /*
                                 * nothing more to do - eveything is
                                 * done on the interrupt return path
                                 */
                                break;

                        case IPI_CALL_FUNC:
                                generic_smp_call_function_interrupt();
                                break;

                        case IPI_CALL_FUNC_SINGLE:
                                generic_smp_call_function_single_interrupt();
                                break;

                        case IPI_CPU_STOP:
                                ipi_cpu_stop(cpu);
                                break;

                        default:
                                printk(KERN_CRIT "CPU%u: Unknown IPI message 0x%x\n",
                                       cpu, nextmsg);
                                break;
                        }
                } while (msgs);
        }

        set_irq_regs(old_regs);
}

void smp_send_reschedule(int cpu)
{
        send_ipi_message(cpumask_of(cpu), IPI_RESCHEDULE);
}

void smp_send_stop(void)
{
        cpumask_t mask = cpu_online_map;
        cpu_clear(smp_processor_id(), mask);
        send_ipi_message(&mask, IPI_CPU_STOP);
}

/*
 * not supported here
 */
int setup_profiling_timer(unsigned int multiplier)
{
        return -EINVAL;
}

static void
on_each_cpu_mask(void (*func)(void *), void *info, int wait,
                const struct cpumask *mask)
{
        preempt_disable();

        smp_call_function_many(mask, func, info, wait);
        if (cpumask_test_cpu(smp_processor_id(), mask))
                func(info);

        preempt_enable();
}

/**********************************************************************/

/*
 * TLB operations
 */
struct tlb_args {
        struct vm_area_struct *ta_vma;
        unsigned long ta_start;
        unsigned long ta_end;
};

static inline void ipi_flush_tlb_all(void *ignored)
{
        local_flush_tlb_all();
}

static inline void ipi_flush_tlb_mm(void *arg)
{
        struct mm_struct *mm = (struct mm_struct *)arg;

        local_flush_tlb_mm(mm);
}

static inline void ipi_flush_tlb_page(void *arg)
{
        struct tlb_args *ta = (struct tlb_args *)arg;

        local_flush_tlb_page(ta->ta_vma, ta->ta_start);
}

static inline void ipi_flush_tlb_kernel_page(void *arg)
{
        struct tlb_args *ta = (struct tlb_args *)arg;

        local_flush_tlb_kernel_page(ta->ta_start);
}

static inline void ipi_flush_tlb_range(void *arg)
{
        struct tlb_args *ta = (struct tlb_args *)arg;

        local_flush_tlb_range(ta->ta_vma, ta->ta_start, ta->ta_end);
}

static inline void ipi_flush_tlb_kernel_range(void *arg)
{
        struct tlb_args *ta = (struct tlb_args *)arg;

        local_flush_tlb_kernel_range(ta->ta_start, ta->ta_end);
}

void flush_tlb_all(void)
{
        if (tlb_ops_need_broadcast())
                on_each_cpu(ipi_flush_tlb_all, NULL, 1);
        else
                local_flush_tlb_all();
}

void flush_tlb_mm(struct mm_struct *mm)
{
        if (tlb_ops_need_broadcast())
                on_each_cpu_mask(ipi_flush_tlb_mm, mm, 1, mm_cpumask(mm));
        else
                local_flush_tlb_mm(mm);
}

void flush_tlb_page(struct vm_area_struct *vma, unsigned long uaddr)
{
        if (tlb_ops_need_broadcast()) {
                struct tlb_args ta;
                ta.ta_vma = vma;
                ta.ta_start = uaddr;
                on_each_cpu_mask(ipi_flush_tlb_page, &ta, 1, mm_cpumask(vma->vm_mm));
        } else
                local_flush_tlb_page(vma, uaddr);
}

void flush_tlb_kernel_page(unsigned long kaddr)
{
        if (tlb_ops_need_broadcast()) {
                struct tlb_args ta;
                ta.ta_start = kaddr;
                on_each_cpu(ipi_flush_tlb_kernel_page, &ta, 1);
        } else
                local_flush_tlb_kernel_page(kaddr);
}

void flush_tlb_range(struct vm_area_struct *vma,
                     unsigned long start, unsigned long end)
{
        if (tlb_ops_need_broadcast()) {
                struct tlb_args ta;
                ta.ta_vma = vma;
                ta.ta_start = start;
                ta.ta_end = end;
                on_each_cpu_mask(ipi_flush_tlb_range, &ta, 1, mm_cpumask(vma->vm_mm));
        } else
                local_flush_tlb_range(vma, start, end);
}

void flush_tlb_kernel_range(unsigned long start, unsigned long end)
{
        if (tlb_ops_need_broadcast()) {
                struct tlb_args ta;
                ta.ta_start = start;
                ta.ta_end = end;
                on_each_cpu(ipi_flush_tlb_kernel_range, &ta, 1);
        } else
                local_flush_tlb_kernel_range(start, end);
}