/*
 * Architecture specific (PPC64) functions for kexec based crash dumps.
 *
 * Copyright (C) 2005, IBM Corp.
 *
 * Created by: Haren Myneni
 *
 * This source code is licensed under the GNU General Public License,
 * Version 2.  See the file COPYING for more details.
 *
 */

#undef DEBUG

#include <linux/kernel.h>
#include <linux/smp.h>
#include <linux/reboot.h>
#include <linux/kexec.h>
#include <linux/bootmem.h>
#include <linux/crash_dump.h>
#include <linux/delay.h>
#include <linux/elf.h>
#include <linux/elfcore.h>
#include <linux/init.h>
#include <linux/irq.h>
#include <linux/types.h>
#include <linux/lmb.h>

#include <asm/processor.h>
#include <asm/machdep.h>
#include <asm/kexec.h>
#include <asm/kdump.h>
#include <asm/prom.h>
#include <asm/firmware.h>
#include <asm/smp.h>
#include <asm/system.h>
#include <asm/setjmp.h>

#ifdef DEBUG
#include <asm/udbg.h>
#define DBG(fmt...) udbg_printf(fmt)
#else
#define DBG(fmt...)
#endif

/* This keeps a track of which one is crashing cpu. */
int crashing_cpu = -1;
static cpumask_t cpus_in_crash = CPU_MASK_NONE;
cpumask_t cpus_in_sr = CPU_MASK_NONE;

#define CRASH_HANDLER_MAX 2
/* NULL terminated list of shutdown handles */
static crash_shutdown_t crash_shutdown_handles[CRASH_HANDLER_MAX+1];
static DEFINE_SPINLOCK(crash_handlers_lock);

#ifdef CONFIG_SMP
static atomic_t enter_on_soft_reset = ATOMIC_INIT(0);

void crash_ipi_callback(struct pt_regs *regs)
{
        int cpu = smp_processor_id();

        if (!cpu_online(cpu))
                return;

        hard_irq_disable();
        if (!cpu_isset(cpu, cpus_in_crash))
                crash_save_cpu(regs, cpu);
        cpu_set(cpu, cpus_in_crash);

        /*
         * Entered via soft-reset - could be the kdump
         * process is invoked using soft-reset or user activated
         * it if some CPU did not respond to an IPI.
         * For soft-reset, the secondary CPU can enter this func
         * twice. 1 - using IPI, and 2. soft-reset.
         * Tell the kexec CPU that entered via soft-reset and ready
         * to go down.
         */
        if (cpu_isset(cpu, cpus_in_sr)) {
                cpu_clear(cpu, cpus_in_sr);
                atomic_inc(&enter_on_soft_reset);
        }

        /*
         * Starting the kdump boot.
         * This barrier is needed to make sure that all CPUs are stopped.
         * If not, soft-reset will be invoked to bring other CPUs.
         */
        while (!cpu_isset(crashing_cpu, cpus_in_crash))
                cpu_relax();

        if (ppc_md.kexec_cpu_down)
                ppc_md.kexec_cpu_down(1, 1);

#ifdef CONFIG_PPC64
        kexec_smp_wait();
#else
        for (;;);       /* FIXME */
#endif

        /* NOTREACHED */
}

/*
 * Wait until all CPUs are entered via soft-reset.
 */
static void crash_soft_reset_check(int cpu)
{
        unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */

        cpu_clear(cpu, cpus_in_sr);
        while (atomic_read(&enter_on_soft_reset) != ncpus)
                cpu_relax();
}


static void crash_kexec_prepare_cpus(int cpu)
{
        unsigned int msecs;

        unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */

        crash_send_ipi(crash_ipi_callback);
        smp_wmb();

        /*
         * FIXME: Until we will have the way to stop other CPUSs reliabally,
         * the crash CPU will send an IPI and wait for other CPUs to
         * respond.
         * Delay of at least 10 seconds.
         */
        printk(KERN_EMERG "Sending IPI to other cpus...\n");
        msecs = 10000;
        while ((cpus_weight(cpus_in_crash) < ncpus) && (--msecs > 0)) {
                cpu_relax();
                mdelay(1);
        }

        /* Would it be better to replace the trap vector here? */

        /*
         * FIXME: In case if we do not get all CPUs, one possibility: ask the
         * user to do soft reset such that we get all.
         * Soft-reset will be used until better mechanism is implemented.
         */
        if (cpus_weight(cpus_in_crash) < ncpus) {
                printk(KERN_EMERG "done waiting: %d cpu(s) not responding\n",
                        ncpus - cpus_weight(cpus_in_crash));
                printk(KERN_EMERG "Activate soft-reset to stop other cpu(s)\n");
                cpus_in_sr = CPU_MASK_NONE;
                atomic_set(&enter_on_soft_reset, 0);
                while (cpus_weight(cpus_in_crash) < ncpus)
                        cpu_relax();
        }
        /*
         * Make sure all CPUs are entered via soft-reset if the kdump is
         * invoked using soft-reset.
         */
        if (cpu_isset(cpu, cpus_in_sr))
                crash_soft_reset_check(cpu);
        /* Leave the IPI callback set */
}

/*
 * This function will be called by secondary cpus or by kexec cpu
 * if soft-reset is activated to stop some CPUs.
 */
void crash_kexec_secondary(struct pt_regs *regs)
{
        int cpu = smp_processor_id();
        unsigned long flags;
        int msecs = 5;

        local_irq_save(flags);
        /* Wait 5ms if the kexec CPU is not entered yet. */
        while (crashing_cpu < 0) {
                if (--msecs < 0) {
                        /*
                         * Either kdump image is not loaded or
                         * kdump process is not started - Probably xmon
                         * exited using 'x'(exit and recover) or
                         * kexec_should_crash() failed for all running tasks.
                         */
                        cpu_clear(cpu, cpus_in_sr);
                        local_irq_restore(flags);
                        return;
                }
                mdelay(1);
                cpu_relax();
        }
        if (cpu == crashing_cpu) {
                /*
                 * Panic CPU will enter this func only via soft-reset.
                 * Wait until all secondary CPUs entered and
                 * then start kexec boot.
                 */
                crash_soft_reset_check(cpu);
                cpu_set(crashing_cpu, cpus_in_crash);
                if (ppc_md.kexec_cpu_down)
                        ppc_md.kexec_cpu_down(1, 0);
                machine_kexec(kexec_crash_image);
                /* NOTREACHED */
        }
        crash_ipi_callback(regs);
}

#else
static void crash_kexec_prepare_cpus(int cpu)
{
        /*
         * move the secondarys to us so that we can copy
         * the new kernel 0-0x100 safely
         *
         * do this if kexec in setup.c ?
         */
#ifdef CONFIG_PPC64
        smp_release_cpus();
#else
        /* FIXME */
#endif
}

void crash_kexec_secondary(struct pt_regs *regs)
{
        cpus_in_sr = CPU_MASK_NONE;
}
#endif
#ifdef CONFIG_SPU_BASE

#include <asm/spu.h>
#include <asm/spu_priv1.h>

struct crash_spu_info {
        struct spu *spu;
        u32 saved_spu_runcntl_RW;
        u32 saved_spu_status_R;
        u32 saved_spu_npc_RW;
        u64 saved_mfc_sr1_RW;
        u64 saved_mfc_dar;
        u64 saved_mfc_dsisr;
};

#define CRASH_NUM_SPUS  16      /* Enough for current hardware */
static struct crash_spu_info crash_spu_info[CRASH_NUM_SPUS];

static void crash_kexec_stop_spus(void)
{
        struct spu *spu;
        int i;
        u64 tmp;

        for (i = 0; i < CRASH_NUM_SPUS; i++) {
                if (!crash_spu_info[i].spu)
                        continue;

                spu = crash_spu_info[i].spu;

                crash_spu_info[i].saved_spu_runcntl_RW =
                        in_be32(&spu->problem->spu_runcntl_RW);
                crash_spu_info[i].saved_spu_status_R =
                        in_be32(&spu->problem->spu_status_R);
                crash_spu_info[i].saved_spu_npc_RW =
                        in_be32(&spu->problem->spu_npc_RW);

                crash_spu_info[i].saved_mfc_dar    = spu_mfc_dar_get(spu);
                crash_spu_info[i].saved_mfc_dsisr  = spu_mfc_dsisr_get(spu);
                tmp = spu_mfc_sr1_get(spu);
                crash_spu_info[i].saved_mfc_sr1_RW = tmp;

                tmp &= ~MFC_STATE1_MASTER_RUN_CONTROL_MASK;
                spu_mfc_sr1_set(spu, tmp);

                __delay(200);
        }
}

void crash_register_spus(struct list_head *list)
{
        struct spu *spu;

        list_for_each_entry(spu, list, full_list) {
                if (WARN_ON(spu->number >= CRASH_NUM_SPUS))
                        continue;

                crash_spu_info[spu->number].spu = spu;
        }
}

#else
static inline void crash_kexec_stop_spus(void)
{
}
#endif /* CONFIG_SPU_BASE */

/*
 * Register a function to be called on shutdown.  Only use this if you
 * can't reset your device in the second kernel.
 */
int crash_shutdown_register(crash_shutdown_t handler)
{
        unsigned int i, rc;

        spin_lock(&crash_handlers_lock);
        for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
                if (!crash_shutdown_handles[i]) {
                        /* Insert handle at first empty entry */
                        crash_shutdown_handles[i] = handler;
                        rc = 0;
                        break;
                }

        if (i == CRASH_HANDLER_MAX) {
                printk(KERN_ERR "Crash shutdown handles full, "
                       "not registered.\n");
                rc = 1;
        }

        spin_unlock(&crash_handlers_lock);
        return rc;
}
EXPORT_SYMBOL(crash_shutdown_register);

int crash_shutdown_unregister(crash_shutdown_t handler)
{
        unsigned int i, rc;

        spin_lock(&crash_handlers_lock);
        for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
                if (crash_shutdown_handles[i] == handler)
                        break;

        if (i == CRASH_HANDLER_MAX) {
                printk(KERN_ERR "Crash shutdown handle not found\n");
                rc = 1;
        } else {
                /* Shift handles down */
                for (; crash_shutdown_handles[i]; i++)
                        crash_shutdown_handles[i] =
                                crash_shutdown_handles[i+1];
                rc = 0;
        }

        spin_unlock(&crash_handlers_lock);
        return rc;
}
EXPORT_SYMBOL(crash_shutdown_unregister);

static unsigned long crash_shutdown_buf[JMP_BUF_LEN];

static int handle_fault(struct pt_regs *regs)
{
        longjmp(crash_shutdown_buf, 1);
        return 0;
}

void default_machine_crash_shutdown(struct pt_regs *regs)
{
        unsigned int i;
        int (*old_handler)(struct pt_regs *regs);


        /*
         * This function is only called after the system
         * has panicked or is otherwise in a critical state.
         * The minimum amount of code to allow a kexec'd kernel
         * to run successfully needs to happen here.
         *
         * In practice this means stopping other cpus in
         * an SMP system.
         * The kernel is broken so disable interrupts.
         */
        hard_irq_disable();

        for_each_irq(i) {
                struct irq_desc *desc = irq_desc + i;

                if (desc->status & IRQ_INPROGRESS)
                        desc->chip->eoi(i);

                if (!(desc->status & IRQ_DISABLED))
                        desc->chip->disable(i);
        }

        /*
         * Call registered shutdown routines savely.  Swap out
         * __debugger_fault_handler, and replace on exit.
         */
        old_handler = __debugger_fault_handler;
        __debugger_fault_handler = handle_fault;
        for (i = 0; crash_shutdown_handles[i]; i++) {
                if (setjmp(crash_shutdown_buf) == 0) {
                        /*
                         * Insert syncs and delay to ensure
                         * instructions in the dangerous region don't
                         * leak away from this protected region.
                         */
                        asm volatile("sync; isync");
                        /* dangerous region */
                        crash_shutdown_handles[i]();
                        asm volatile("sync; isync");
                }
        }
        __debugger_fault_handler = old_handler;

        /*
         * Make a note of crashing cpu. Will be used in machine_kexec
         * such that another IPI will not be sent.
         */
        crashing_cpu = smp_processor_id();
        crash_save_cpu(regs, crashing_cpu);
        crash_kexec_prepare_cpus(crashing_cpu);
        cpu_set(crashing_cpu, cpus_in_crash);
        crash_kexec_stop_spus();
        if (ppc_md.kexec_cpu_down)
                ppc_md.kexec_cpu_down(1, 0);
}