/*
 * Xtensa SMP support functions.
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2008 - 2013 Tensilica Inc.
 *
 * Chris Zankel <chris@zankel.net>
 * Joe Taylor <joe@tensilica.com>
 * Pete Delaney <piet@tensilica.com
 */

#include <linux/cpu.h>
#include <linux/cpumask.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/irqdomain.h>
#include <linux/irq.h>
#include <linux/kdebug.h>
#include <linux/module.h>
#include <linux/sched/mm.h>
#include <linux/sched/hotplug.h>
#include <linux/sched/task_stack.h>
#include <linux/reboot.h>
#include <linux/seq_file.h>
#include <linux/smp.h>
#include <linux/thread_info.h>

#include <asm/cacheflush.h>
#include <asm/kdebug.h>
#include <asm/mmu_context.h>
#include <asm/mxregs.h>
#include <asm/platform.h>
#include <asm/tlbflush.h>
#include <asm/traps.h>

#ifdef CONFIG_SMP
# if XCHAL_HAVE_S32C1I == 0
#  error "The S32C1I option is required for SMP."
# endif
#endif

static void system_invalidate_dcache_range(unsigned long start,
                unsigned long size);
static void system_flush_invalidate_dcache_range(unsigned long start,
                unsigned long size);

/* IPI (Inter Process Interrupt) */

#define IPI_IRQ 0

static irqreturn_t ipi_interrupt(int irq, void *dev_id);

void ipi_init(void)
{
        unsigned irq = irq_create_mapping(NULL, IPI_IRQ);
        if (request_irq(irq, ipi_interrupt, IRQF_PERCPU, "ipi", NULL))
                pr_err("Failed to request irq %u (ipi)\n", irq);
}

static inline unsigned int get_core_count(void)
{
        /* Bits 18..21 of SYSCFGID contain the core count minus 1. */
        unsigned int syscfgid = get_er(SYSCFGID);
        return ((syscfgid >> 18) & 0xf) + 1;
}

static inline int get_core_id(void)
{
        /* Bits 0...18 of SYSCFGID contain the core id  */
        unsigned int core_id = get_er(SYSCFGID);
        return core_id & 0x3fff;
}

void __init smp_prepare_cpus(unsigned int max_cpus)
{
        unsigned i;

        for_each_possible_cpu(i)
                set_cpu_present(i, true);
}

void __init smp_init_cpus(void)
{
        unsigned i;
        unsigned int ncpus = get_core_count();
        unsigned int core_id = get_core_id();

        pr_info("%s: Core Count = %d\n", __func__, ncpus);
        pr_info("%s: Core Id = %d\n", __func__, core_id);

        if (ncpus > NR_CPUS) {
                ncpus = NR_CPUS;
                pr_info("%s: limiting core count by %d\n", __func__, ncpus);
        }

        for (i = 0; i < ncpus; ++i)
                set_cpu_possible(i, true);
}

void __init smp_prepare_boot_cpu(void)
{
        unsigned int cpu = smp_processor_id();
        BUG_ON(cpu != 0);
        cpu_asid_cache(cpu) = ASID_USER_FIRST;
}

void __init smp_cpus_done(unsigned int max_cpus)
{
}

static int boot_secondary_processors = 1; /* Set with xt-gdb via .xt-gdb */
static DECLARE_COMPLETION(cpu_running);

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

        init_mmu();

#ifdef CONFIG_DEBUG_MISC
        if (boot_secondary_processors == 0) {
                pr_debug("%s: boot_secondary_processors:%d; Hanging cpu:%d\n",
                        __func__, boot_secondary_processors, cpu);
                for (;;)
                        __asm__ __volatile__ ("waiti " __stringify(LOCKLEVEL));
        }

        pr_debug("%s: boot_secondary_processors:%d; Booting cpu:%d\n",
                __func__, boot_secondary_processors, cpu);
#endif
        /* Init EXCSAVE1 */

        secondary_trap_init();

        /* All kernel threads share the same mm context. */

        mmget(mm);
        mmgrab(mm);
        current->active_mm = mm;
        cpumask_set_cpu(cpu, mm_cpumask(mm));
        enter_lazy_tlb(mm, current);

        trace_hardirqs_off();

        calibrate_delay();

        notify_cpu_starting(cpu);

        secondary_init_irq();
        local_timer_setup(cpu);

        set_cpu_online(cpu, true);

        local_irq_enable();

        complete(&cpu_running);

        cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
}

static void mx_cpu_start(void *p)
{
        unsigned cpu = (unsigned)p;
        unsigned long run_stall_mask = get_er(MPSCORE);

        set_er(run_stall_mask & ~(1u << cpu), MPSCORE);
        pr_debug("%s: cpu: %d, run_stall_mask: %lx ---> %lx\n",
                        __func__, cpu, run_stall_mask, get_er(MPSCORE));
}

static void mx_cpu_stop(void *p)
{
        unsigned cpu = (unsigned)p;
        unsigned long run_stall_mask = get_er(MPSCORE);

        set_er(run_stall_mask | (1u << cpu), MPSCORE);
        pr_debug("%s: cpu: %d, run_stall_mask: %lx ---> %lx\n",
                        __func__, cpu, run_stall_mask, get_er(MPSCORE));
}

#ifdef CONFIG_HOTPLUG_CPU
unsigned long cpu_start_id __cacheline_aligned;
#endif
unsigned long cpu_start_ccount;

static int boot_secondary(unsigned int cpu, struct task_struct *ts)
{
        unsigned long timeout = jiffies + msecs_to_jiffies(1000);
        unsigned long ccount;
        int i;

#ifdef CONFIG_HOTPLUG_CPU
        WRITE_ONCE(cpu_start_id, cpu);
        /* Pairs with the third memw in the cpu_restart */
        mb();
        system_flush_invalidate_dcache_range((unsigned long)&cpu_start_id,
                                             sizeof(cpu_start_id));
#endif
        smp_call_function_single(0, mx_cpu_start, (void *)cpu, 1);

        for (i = 0; i < 2; ++i) {
                do
                        ccount = get_ccount();
                while (!ccount);

                WRITE_ONCE(cpu_start_ccount, ccount);

                do {
                        /*
                         * Pairs with the first two memws in the
                         * .Lboot_secondary.
                         */
                        mb();
                        ccount = READ_ONCE(cpu_start_ccount);
                } while (ccount && time_before(jiffies, timeout));

                if (ccount) {
                        smp_call_function_single(0, mx_cpu_stop,
                                                 (void *)cpu, 1);
                        WRITE_ONCE(cpu_start_ccount, 0);
                        return -EIO;
                }
        }
        return 0;
}

int __cpu_up(unsigned int cpu, struct task_struct *idle)
{
        int ret = 0;

        if (cpu_asid_cache(cpu) == 0)
                cpu_asid_cache(cpu) = ASID_USER_FIRST;

        start_info.stack = (unsigned long)task_pt_regs(idle);
        wmb();

        pr_debug("%s: Calling wakeup_secondary(cpu:%d, idle:%p, sp: %08lx)\n",
                        __func__, cpu, idle, start_info.stack);

        init_completion(&cpu_running);
        ret = boot_secondary(cpu, idle);
        if (ret == 0) {
                wait_for_completion_timeout(&cpu_running,
                                msecs_to_jiffies(1000));
                if (!cpu_online(cpu))
                        ret = -EIO;
        }

        if (ret)
                pr_err("CPU %u failed to boot\n", cpu);

        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();

        /*
         * 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();

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

        clear_tasks_mm_cpumask(cpu);

        return 0;
}

static void platform_cpu_kill(unsigned int cpu)
{
        smp_call_function_single(0, mx_cpu_stop, (void *)cpu, true);
}

/*
 * 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)
{
        unsigned long timeout = jiffies + msecs_to_jiffies(1000);
        while (time_before(jiffies, timeout)) {
                system_invalidate_dcache_range((unsigned long)&cpu_start_id,
                                               sizeof(cpu_start_id));
                /* Pairs with the second memw in the cpu_restart */
                mb();
                if (READ_ONCE(cpu_start_id) == -cpu) {
                        platform_cpu_kill(cpu);
                        return;
                }
        }
        pr_err("CPU%u: unable to kill\n", cpu);
}

void arch_cpu_idle_dead(void)
{
        cpu_die();
}
/*
 * 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)
{
        idle_task_exit();
        local_irq_disable();
        __asm__ __volatile__(
                        "       movi    a2, cpu_restart\n"
                        "       jx      a2\n");
}

#endif /* CONFIG_HOTPLUG_CPU */

enum ipi_msg_type {
        IPI_RESCHEDULE = 0,
        IPI_CALL_FUNC,
        IPI_CPU_STOP,
        IPI_MAX
};

static const struct {
        const char *short_text;
        const char *long_text;
} ipi_text[] = {
        { .short_text = "RES", .long_text = "Rescheduling interrupts" },
        { .short_text = "CAL", .long_text = "Function call interrupts" },
        { .short_text = "DIE", .long_text = "CPU shutdown interrupts" },
};

struct ipi_data {
        unsigned long ipi_count[IPI_MAX];
};

static DEFINE_PER_CPU(struct ipi_data, ipi_data);

static void send_ipi_message(const struct cpumask *callmask,
                enum ipi_msg_type msg_id)
{
        int index;
        unsigned long mask = 0;

        for_each_cpu(index, callmask)
                mask |= 1 << index;

        set_er(mask, MIPISET(msg_id));
}

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);
}

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

void smp_send_stop(void)
{
        struct cpumask targets;

        cpumask_copy(&targets, cpu_online_mask);
        cpumask_clear_cpu(smp_processor_id(), &targets);
        send_ipi_message(&targets, IPI_CPU_STOP);
}

static void ipi_cpu_stop(unsigned int cpu)
{
        set_cpu_online(cpu, false);
        machine_halt();
}

irqreturn_t ipi_interrupt(int irq, void *dev_id)
{
        unsigned int cpu = smp_processor_id();
        struct ipi_data *ipi = &per_cpu(ipi_data, cpu);

        for (;;) {
                unsigned int msg;

                msg = get_er(MIPICAUSE(cpu));
                set_er(msg, MIPICAUSE(cpu));

                if (!msg)
                        break;

                if (msg & (1 << IPI_CALL_FUNC)) {
                        ++ipi->ipi_count[IPI_CALL_FUNC];
                        generic_smp_call_function_interrupt();
                }

                if (msg & (1 << IPI_RESCHEDULE)) {
                        ++ipi->ipi_count[IPI_RESCHEDULE];
                        scheduler_ipi();
                }

                if (msg & (1 << IPI_CPU_STOP)) {
                        ++ipi->ipi_count[IPI_CPU_STOP];
                        ipi_cpu_stop(cpu);
                }
        }

        return IRQ_HANDLED;
}

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

        for (i = 0; i < IPI_MAX; ++i) {
                seq_printf(p, "%*s:", prec, ipi_text[i].short_text);
                for_each_online_cpu(cpu)
                        seq_printf(p, " %10lu",
                                        per_cpu(ipi_data, cpu).ipi_count[i]);
                seq_printf(p, "   %s\n", ipi_text[i].long_text);
        }
}

int setup_profiling_timer(unsigned int multiplier)
{
        pr_debug("setup_profiling_timer %d\n", multiplier);
        return 0;
}

/* TLB flush functions */

struct flush_data {
        struct vm_area_struct *vma;
        unsigned long addr1;
        unsigned long addr2;
};

static void ipi_flush_tlb_all(void *arg)
{
        local_flush_tlb_all();
}

void flush_tlb_all(void)
{
        on_each_cpu(ipi_flush_tlb_all, NULL, 1);
}

static void ipi_flush_tlb_mm(void *arg)
{
        local_flush_tlb_mm(arg);
}

void flush_tlb_mm(struct mm_struct *mm)
{
        on_each_cpu(ipi_flush_tlb_mm, mm, 1);
}

static void ipi_flush_tlb_page(void *arg)
{
        struct flush_data *fd = arg;
        local_flush_tlb_page(fd->vma, fd->addr1);
}

void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
{
        struct flush_data fd = {
                .vma = vma,
                .addr1 = addr,
        };
        on_each_cpu(ipi_flush_tlb_page, &fd, 1);
}

static void ipi_flush_tlb_range(void *arg)
{
        struct flush_data *fd = arg;
        local_flush_tlb_range(fd->vma, fd->addr1, fd->addr2);
}

void flush_tlb_range(struct vm_area_struct *vma,
                     unsigned long start, unsigned long end)
{
        struct flush_data fd = {
                .vma = vma,
                .addr1 = start,
                .addr2 = end,
        };
        on_each_cpu(ipi_flush_tlb_range, &fd, 1);
}

static void ipi_flush_tlb_kernel_range(void *arg)
{
        struct flush_data *fd = arg;
        local_flush_tlb_kernel_range(fd->addr1, fd->addr2);
}

void flush_tlb_kernel_range(unsigned long start, unsigned long end)
{
        struct flush_data fd = {
                .addr1 = start,
                .addr2 = end,
        };
        on_each_cpu(ipi_flush_tlb_kernel_range, &fd, 1);
}

/* Cache flush functions */

static void ipi_flush_cache_all(void *arg)
{
        local_flush_cache_all();
}

void flush_cache_all(void)
{
        on_each_cpu(ipi_flush_cache_all, NULL, 1);
}

static void ipi_flush_cache_page(void *arg)
{
        struct flush_data *fd = arg;
        local_flush_cache_page(fd->vma, fd->addr1, fd->addr2);
}

void flush_cache_page(struct vm_area_struct *vma,
                     unsigned long address, unsigned long pfn)
{
        struct flush_data fd = {
                .vma = vma,
                .addr1 = address,
                .addr2 = pfn,
        };
        on_each_cpu(ipi_flush_cache_page, &fd, 1);
}

static void ipi_flush_cache_range(void *arg)
{
        struct flush_data *fd = arg;
        local_flush_cache_range(fd->vma, fd->addr1, fd->addr2);
}

void flush_cache_range(struct vm_area_struct *vma,
                     unsigned long start, unsigned long end)
{
        struct flush_data fd = {
                .vma = vma,
                .addr1 = start,
                .addr2 = end,
        };
        on_each_cpu(ipi_flush_cache_range, &fd, 1);
}

static void ipi_flush_icache_range(void *arg)
{
        struct flush_data *fd = arg;
        local_flush_icache_range(fd->addr1, fd->addr2);
}

void flush_icache_range(unsigned long start, unsigned long end)
{
        struct flush_data fd = {
                .addr1 = start,
                .addr2 = end,
        };
        on_each_cpu(ipi_flush_icache_range, &fd, 1);
}
EXPORT_SYMBOL(flush_icache_range);

/* ------------------------------------------------------------------------- */

static void ipi_invalidate_dcache_range(void *arg)
{
        struct flush_data *fd = arg;
        __invalidate_dcache_range(fd->addr1, fd->addr2);
}

static void system_invalidate_dcache_range(unsigned long start,
                unsigned long size)
{
        struct flush_data fd = {
                .addr1 = start,
                .addr2 = size,
        };
        on_each_cpu(ipi_invalidate_dcache_range, &fd, 1);
}

static void ipi_flush_invalidate_dcache_range(void *arg)
{
        struct flush_data *fd = arg;
        __flush_invalidate_dcache_range(fd->addr1, fd->addr2);
}

static void system_flush_invalidate_dcache_range(unsigned long start,
                unsigned long size)
{
        struct flush_data fd = {
                .addr1 = start,
                .addr2 = size,
        };
        on_each_cpu(ipi_flush_invalidate_dcache_range, &fd, 1);
}