/*
 * IPI management based on arch/arm/kernel/smp.c (Copyright 2002 ARM Limited)
 *
 * Copyright 2007-2009 Analog Devices Inc.
 *                         Philippe Gerum <rpm@xenomai.org>
 *
 * Licensed under the GPL-2.
 */

#include <linux/module.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/sched/mm.h>
#include <linux/sched/task_stack.h>
#include <linux/interrupt.h>
#include <linux/cache.h>
#include <linux/clockchips.h>
#include <linux/profile.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/cpu.h>
#include <linux/smp.h>
#include <linux/cpumask.h>
#include <linux/seq_file.h>
#include <linux/irq.h>
#include <linux/slab.h>
#include <linux/atomic.h>
#include <asm/cacheflush.h>
#include <asm/irq_handler.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/processor.h>
#include <asm/ptrace.h>
#include <asm/cpu.h>
#include <asm/time.h>
#include <linux/err.h>

/*
 * Anomaly notes:
 * 05000120 - we always define corelock as 32-bit integer in L2
 */
struct corelock_slot corelock __attribute__ ((__section__(".l2.bss")));

#ifdef CONFIG_ICACHE_FLUSH_L1
unsigned long blackfin_iflush_l1_entry[NR_CPUS];
#endif

struct blackfin_initial_pda initial_pda_coreb;

enum ipi_message_type {
        BFIN_IPI_NONE,
        BFIN_IPI_TIMER,
        BFIN_IPI_RESCHEDULE,
        BFIN_IPI_CALL_FUNC,
        BFIN_IPI_CPU_STOP,
};

struct blackfin_flush_data {
        unsigned long start;
        unsigned long end;
};

void *secondary_stack;

static struct blackfin_flush_data smp_flush_data;

static DEFINE_SPINLOCK(stop_lock);

/* A magic number - stress test shows this is safe for common cases */
#define BFIN_IPI_MSGQ_LEN 5

/* Simple FIFO buffer, overflow leads to panic */
struct ipi_data {
        atomic_t count;
        atomic_t bits;
};

static DEFINE_PER_CPU(struct ipi_data, bfin_ipi);

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_irq_disable();

        while (1)
                SSYNC();
}

static void ipi_flush_icache(void *info)
{
        struct blackfin_flush_data *fdata = info;

        /* Invalidate the memory holding the bounds of the flushed region. */
        blackfin_dcache_invalidate_range((unsigned long)fdata,
                                         (unsigned long)fdata + sizeof(*fdata));

        /* Make sure all write buffers in the data side of the core
         * are flushed before trying to invalidate the icache.  This
         * needs to be after the data flush and before the icache
         * flush so that the SSYNC does the right thing in preventing
         * the instruction prefetcher from hitting things in cached
         * memory at the wrong time -- it runs much further ahead than
         * the pipeline.
         */
        SSYNC();

        /* ipi_flaush_icache is invoked by generic flush_icache_range,
         * so call blackfin arch icache flush directly here.
         */
        blackfin_icache_flush_range(fdata->start, fdata->end);
}

/* Use IRQ_SUPPLE_0 to request reschedule.
 * When returning from interrupt to user space,
 * there is chance to reschedule */
static irqreturn_t ipi_handler_int0(int irq, void *dev_instance)
{
        unsigned int cpu = smp_processor_id();

        platform_clear_ipi(cpu, IRQ_SUPPLE_0);
        return IRQ_HANDLED;
}

DECLARE_PER_CPU(struct clock_event_device, coretmr_events);
void ipi_timer(void)
{
        int cpu = smp_processor_id();
        struct clock_event_device *evt = &per_cpu(coretmr_events, cpu);
        evt->event_handler(evt);
}

static irqreturn_t ipi_handler_int1(int irq, void *dev_instance)
{
        struct ipi_data *bfin_ipi_data;
        unsigned int cpu = smp_processor_id();
        unsigned long pending;
        unsigned long msg;

        platform_clear_ipi(cpu, IRQ_SUPPLE_1);

        smp_rmb();
        bfin_ipi_data = this_cpu_ptr(&bfin_ipi);
        while ((pending = atomic_xchg(&bfin_ipi_data->bits, 0)) != 0) {
                msg = 0;
                do {
                        msg = find_next_bit(&pending, BITS_PER_LONG, msg + 1);
                        switch (msg) {
                        case BFIN_IPI_TIMER:
                                ipi_timer();
                                break;
                        case BFIN_IPI_RESCHEDULE:
                                scheduler_ipi();
                                break;
                        case BFIN_IPI_CALL_FUNC:
                                generic_smp_call_function_interrupt();
                                break;
                        case BFIN_IPI_CPU_STOP:
                                ipi_cpu_stop(cpu);
                                break;
                        default:
                                goto out;
                        }
                        atomic_dec(&bfin_ipi_data->count);
                } while (msg < BITS_PER_LONG);

        }
out:
        return IRQ_HANDLED;
}

static void bfin_ipi_init(void)
{
        unsigned int cpu;
        struct ipi_data *bfin_ipi_data;
        for_each_possible_cpu(cpu) {
                bfin_ipi_data = &per_cpu(bfin_ipi, cpu);
                atomic_set(&bfin_ipi_data->bits, 0);
                atomic_set(&bfin_ipi_data->count, 0);
        }
}

void send_ipi(const struct cpumask *cpumask, enum ipi_message_type msg)
{
        unsigned int cpu;
        struct ipi_data *bfin_ipi_data;
        unsigned long flags;

        local_irq_save(flags);
        for_each_cpu(cpu, cpumask) {
                bfin_ipi_data = &per_cpu(bfin_ipi, cpu);
                atomic_or((1 << msg), &bfin_ipi_data->bits);
                atomic_inc(&bfin_ipi_data->count);
        }
        local_irq_restore(flags);
        smp_wmb();
        for_each_cpu(cpu, cpumask)
                platform_send_ipi_cpu(cpu, IRQ_SUPPLE_1);
}

void arch_send_call_function_single_ipi(int cpu)
{
        send_ipi(cpumask_of(cpu), BFIN_IPI_CALL_FUNC);
}

void arch_send_call_function_ipi_mask(const struct cpumask *mask)
{
        send_ipi(mask, BFIN_IPI_CALL_FUNC);
}

void smp_send_reschedule(int cpu)
{
        send_ipi(cpumask_of(cpu), BFIN_IPI_RESCHEDULE);

        return;
}

void smp_send_msg(const struct cpumask *mask, unsigned long type)
{
        send_ipi(mask, type);
}

void smp_timer_broadcast(const struct cpumask *mask)
{
        smp_send_msg(mask, BFIN_IPI_TIMER);
}

void smp_send_stop(void)
{
        cpumask_t callmap;

        preempt_disable();
        cpumask_copy(&callmap, cpu_online_mask);
        cpumask_clear_cpu(smp_processor_id(), &callmap);
        if (!cpumask_empty(&callmap))
                send_ipi(&callmap, BFIN_IPI_CPU_STOP);

        preempt_enable();

        return;
}

int __cpu_up(unsigned int cpu, struct task_struct *idle)
{
        int ret;

        secondary_stack = task_stack_page(idle) + THREAD_SIZE;

        ret = platform_boot_secondary(cpu, idle);

        secondary_stack = NULL;

        return ret;
}

static void setup_secondary(unsigned int cpu)
{
        unsigned long ilat;

        bfin_write_IMASK(0);
        CSYNC();
        ilat = bfin_read_ILAT();
        CSYNC();
        bfin_write_ILAT(ilat);
        CSYNC();

        /* Enable interrupt levels IVG7-15. IARs have been already
         * programmed by the boot CPU.  */
        bfin_irq_flags |= IMASK_IVG15 |
            IMASK_IVG14 | IMASK_IVG13 | IMASK_IVG12 | IMASK_IVG11 |
            IMASK_IVG10 | IMASK_IVG9 | IMASK_IVG8 | IMASK_IVG7 | IMASK_IVGHW;
}

void secondary_start_kernel(void)
{
        unsigned int cpu = smp_processor_id();
        struct mm_struct *mm = &init_mm;

        if (_bfin_swrst & SWRST_DBL_FAULT_B) {
                printk(KERN_EMERG "CoreB Recovering from DOUBLE FAULT event\n");
#ifdef CONFIG_DEBUG_DOUBLEFAULT
                printk(KERN_EMERG " While handling exception (EXCAUSE = %#x) at %pF\n",
                        initial_pda_coreb.seqstat_doublefault & SEQSTAT_EXCAUSE,
                        initial_pda_coreb.retx_doublefault);
                printk(KERN_NOTICE "   DCPLB_FAULT_ADDR: %pF\n",
                        initial_pda_coreb.dcplb_doublefault_addr);
                printk(KERN_NOTICE "   ICPLB_FAULT_ADDR: %pF\n",
                        initial_pda_coreb.icplb_doublefault_addr);
#endif
                printk(KERN_NOTICE " The instruction at %pF caused a double exception\n",
                        initial_pda_coreb.retx);
        }

        /*
         * We want the D-cache to be enabled early, in case the atomic
         * support code emulates cache coherence (see
         * __ARCH_SYNC_CORE_DCACHE).
         */
        init_exception_vectors();

        local_irq_disable();

        /* Attach the new idle task to the global mm. */
        mmget(mm);
        mmgrab(mm);
        current->active_mm = mm;

        preempt_disable();

        setup_secondary(cpu);

        platform_secondary_init(cpu);
        /* setup local core timer */
        bfin_local_timer_setup();

        local_irq_enable();

        bfin_setup_caches(cpu);

        notify_cpu_starting(cpu);
        /*
         * Calibrate loops per jiffy value.
         * IRQs need to be enabled here - D-cache can be invalidated
         * in timer irq handler, so core B can read correct jiffies.
         */
        calibrate_delay();

        /* We are done with local CPU inits, unblock the boot CPU. */
        set_cpu_online(cpu, true);
        cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
}

void __init smp_prepare_boot_cpu(void)
{
}

void __init smp_prepare_cpus(unsigned int max_cpus)
{
        platform_prepare_cpus(max_cpus);
        bfin_ipi_init();
        platform_request_ipi(IRQ_SUPPLE_0, ipi_handler_int0);
        platform_request_ipi(IRQ_SUPPLE_1, ipi_handler_int1);
}

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

        for_each_online_cpu(cpu)
                bogosum += 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 smp_icache_flush_range_others(unsigned long start, unsigned long end)
{
        smp_flush_data.start = start;
        smp_flush_data.end = end;

        preempt_disable();
        if (smp_call_function(&ipi_flush_icache, &smp_flush_data, 1))
                printk(KERN_WARNING "SMP: failed to run I-cache flush request on other CPUs\n");
        preempt_enable();
}
EXPORT_SYMBOL_GPL(smp_icache_flush_range_others);

#ifdef __ARCH_SYNC_CORE_ICACHE
unsigned long icache_invld_count[NR_CPUS];
void resync_core_icache(void)
{
        unsigned int cpu = get_cpu();
        blackfin_invalidate_entire_icache();
        icache_invld_count[cpu]++;
        put_cpu();
}
EXPORT_SYMBOL(resync_core_icache);
#endif

#ifdef __ARCH_SYNC_CORE_DCACHE
unsigned long dcache_invld_count[NR_CPUS];
unsigned long barrier_mask __attribute__ ((__section__(".l2.bss")));

void resync_core_dcache(void)
{
        unsigned int cpu = get_cpu();
        blackfin_invalidate_entire_dcache();
        dcache_invld_count[cpu]++;
        put_cpu();
}
EXPORT_SYMBOL(resync_core_dcache);
#endif

#ifdef CONFIG_HOTPLUG_CPU
int __cpu_disable(void)
{
        unsigned int cpu = smp_processor_id();

        if (cpu == 0)
                return -EPERM;

        set_cpu_online(cpu, false);
        return 0;
}

int __cpu_die(unsigned int cpu)
{
        return cpu_wait_death(cpu, 5);
}

void cpu_die(void)
{
        (void)cpu_report_death();

        atomic_dec(&init_mm.mm_users);
        atomic_dec(&init_mm.mm_count);

        local_irq_disable();
        platform_cpu_die();
}
#endif