#undef DEBUG

/*
 * ARM performance counter support.
 *
 * Copyright (C) 2009 picoChip Designs, Ltd., Jamie Iles
 * Copyright (C) 2010 ARM Ltd., Will Deacon <will.deacon@arm.com>
 *
 * This code is based on the sparc64 perf event code, which is in turn based
 * on the x86 code. Callchain code is based on the ARM OProfile backtrace
 * code.
 */
#define pr_fmt(fmt) "hw perfevents: " fmt

#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/perf_event.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>

#include <asm/cputype.h>
#include <asm/irq.h>
#include <asm/irq_regs.h>
#include <asm/pmu.h>
#include <asm/stacktrace.h>

static struct platform_device *pmu_device;

/*
 * Hardware lock to serialize accesses to PMU registers. Needed for the
 * read/modify/write sequences.
 */
static DEFINE_RAW_SPINLOCK(pmu_lock);

/*
 * ARMv6 supports a maximum of 3 events, starting from index 1. If we add
 * another platform that supports more, we need to increase this to be the
 * largest of all platforms.
 *
 * ARMv7 supports up to 32 events:
 *  cycle counter CCNT + 31 events counters CNT0..30.
 *  Cortex-A8 has 1+4 counters, Cortex-A9 has 1+6 counters.
 */
#define ARMPMU_MAX_HWEVENTS             33

/* The events for a given CPU. */
struct cpu_hw_events {
        /*
         * The events that are active on the CPU for the given index. Index 0
         * is reserved.
         */
        struct perf_event       *events[ARMPMU_MAX_HWEVENTS];

        /*
         * A 1 bit for an index indicates that the counter is being used for
         * an event. A 0 means that the counter can be used.
         */
        unsigned long           used_mask[BITS_TO_LONGS(ARMPMU_MAX_HWEVENTS)];

        /*
         * A 1 bit for an index indicates that the counter is actively being
         * used.
         */
        unsigned long           active_mask[BITS_TO_LONGS(ARMPMU_MAX_HWEVENTS)];
};
static DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events);

struct arm_pmu {
        enum arm_perf_pmu_ids id;
        const char      *name;
        irqreturn_t     (*handle_irq)(int irq_num, void *dev);
        void            (*enable)(struct hw_perf_event *evt, int idx);
        void            (*disable)(struct hw_perf_event *evt, int idx);
        int             (*get_event_idx)(struct cpu_hw_events *cpuc,
                                         struct hw_perf_event *hwc);
        u32             (*read_counter)(int idx);
        void            (*write_counter)(int idx, u32 val);
        void            (*start)(void);
        void            (*stop)(void);
        const unsigned  (*cache_map)[PERF_COUNT_HW_CACHE_MAX]
                                    [PERF_COUNT_HW_CACHE_OP_MAX]
                                    [PERF_COUNT_HW_CACHE_RESULT_MAX];
        const unsigned  (*event_map)[PERF_COUNT_HW_MAX];
        u32             raw_event_mask;
        int             num_events;
        u64             max_period;
};

/* Set at runtime when we know what CPU type we are. */
static const struct arm_pmu *armpmu;

enum arm_perf_pmu_ids
armpmu_get_pmu_id(void)
{
        int id = -ENODEV;

        if (armpmu != NULL)
                id = armpmu->id;

        return id;
}
EXPORT_SYMBOL_GPL(armpmu_get_pmu_id);

int
armpmu_get_max_events(void)
{
        int max_events = 0;

        if (armpmu != NULL)
                max_events = armpmu->num_events;

        return max_events;
}
EXPORT_SYMBOL_GPL(armpmu_get_max_events);

int perf_num_counters(void)
{
        return armpmu_get_max_events();
}
EXPORT_SYMBOL_GPL(perf_num_counters);

#define HW_OP_UNSUPPORTED               0xFFFF

#define C(_x) \
        PERF_COUNT_HW_CACHE_##_x

#define CACHE_OP_UNSUPPORTED            0xFFFF

static int
armpmu_map_cache_event(u64 config)
{
        unsigned int cache_type, cache_op, cache_result, ret;

        cache_type = (config >>  0) & 0xff;
        if (cache_type >= PERF_COUNT_HW_CACHE_MAX)
                return -EINVAL;

        cache_op = (config >>  8) & 0xff;
        if (cache_op >= PERF_COUNT_HW_CACHE_OP_MAX)
                return -EINVAL;

        cache_result = (config >> 16) & 0xff;
        if (cache_result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
                return -EINVAL;

        ret = (int)(*armpmu->cache_map)[cache_type][cache_op][cache_result];

        if (ret == CACHE_OP_UNSUPPORTED)
                return -ENOENT;

        return ret;
}

static int
armpmu_map_event(u64 config)
{
        int mapping = (*armpmu->event_map)[config];
        return mapping == HW_OP_UNSUPPORTED ? -EOPNOTSUPP : mapping;
}

static int
armpmu_map_raw_event(u64 config)
{
        return (int)(config & armpmu->raw_event_mask);
}

static int
armpmu_event_set_period(struct perf_event *event,
                        struct hw_perf_event *hwc,
                        int idx)
{
        s64 left = local64_read(&hwc->period_left);
        s64 period = hwc->sample_period;
        int ret = 0;

        if (unlikely(left <= -period)) {
                left = period;
                local64_set(&hwc->period_left, left);
                hwc->last_period = period;
                ret = 1;
        }

        if (unlikely(left <= 0)) {
                left += period;
                local64_set(&hwc->period_left, left);
                hwc->last_period = period;
                ret = 1;
        }

        if (left > (s64)armpmu->max_period)
                left = armpmu->max_period;

        local64_set(&hwc->prev_count, (u64)-left);

        armpmu->write_counter(idx, (u64)(-left) & 0xffffffff);

        perf_event_update_userpage(event);

        return ret;
}

static u64
armpmu_event_update(struct perf_event *event,
                    struct hw_perf_event *hwc,
                    int idx)
{
        int shift = 64 - 32;
        s64 prev_raw_count, new_raw_count;
        u64 delta;

again:
        prev_raw_count = local64_read(&hwc->prev_count);
        new_raw_count = armpmu->read_counter(idx);

        if (local64_cmpxchg(&hwc->prev_count, prev_raw_count,
                             new_raw_count) != prev_raw_count)
                goto again;

        delta = (new_raw_count << shift) - (prev_raw_count << shift);
        delta >>= shift;

        local64_add(delta, &event->count);
        local64_sub(delta, &hwc->period_left);

        return new_raw_count;
}

static void
armpmu_read(struct perf_event *event)
{
        struct hw_perf_event *hwc = &event->hw;

        /* Don't read disabled counters! */
        if (hwc->idx < 0)
                return;

        armpmu_event_update(event, hwc, hwc->idx);
}

static void
armpmu_stop(struct perf_event *event, int flags)
{
        struct hw_perf_event *hwc = &event->hw;

        if (!armpmu)
                return;

        /*
         * ARM pmu always has to update the counter, so ignore
         * PERF_EF_UPDATE, see comments in armpmu_start().
         */
        if (!(hwc->state & PERF_HES_STOPPED)) {
                armpmu->disable(hwc, hwc->idx);
                barrier(); /* why? */
                armpmu_event_update(event, hwc, hwc->idx);
                hwc->state |= PERF_HES_STOPPED | PERF_HES_UPTODATE;
        }
}

static void
armpmu_start(struct perf_event *event, int flags)
{
        struct hw_perf_event *hwc = &event->hw;

        if (!armpmu)
                return;

        /*
         * ARM pmu always has to reprogram the period, so ignore
         * PERF_EF_RELOAD, see the comment below.
         */
        if (flags & PERF_EF_RELOAD)
                WARN_ON_ONCE(!(hwc->state & PERF_HES_UPTODATE));

        hwc->state = 0;
        /*
         * Set the period again. Some counters can't be stopped, so when we
         * were stopped we simply disabled the IRQ source and the counter
         * may have been left counting. If we don't do this step then we may
         * get an interrupt too soon or *way* too late if the overflow has
         * happened since disabling.
         */
        armpmu_event_set_period(event, hwc, hwc->idx);
        armpmu->enable(hwc, hwc->idx);
}

static void
armpmu_del(struct perf_event *event, int flags)
{
        struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
        struct hw_perf_event *hwc = &event->hw;
        int idx = hwc->idx;

        WARN_ON(idx < 0);

        clear_bit(idx, cpuc->active_mask);
        armpmu_stop(event, PERF_EF_UPDATE);
        cpuc->events[idx] = NULL;
        clear_bit(idx, cpuc->used_mask);

        perf_event_update_userpage(event);
}

static int
armpmu_add(struct perf_event *event, int flags)
{
        struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
        struct hw_perf_event *hwc = &event->hw;
        int idx;
        int err = 0;

        perf_pmu_disable(event->pmu);

        /* If we don't have a space for the counter then finish early. */
        idx = armpmu->get_event_idx(cpuc, hwc);
        if (idx < 0) {
                err = idx;
                goto out;
        }

        /*
         * If there is an event in the counter we are going to use then make
         * sure it is disabled.
         */
        event->hw.idx = idx;
        armpmu->disable(hwc, idx);
        cpuc->events[idx] = event;
        set_bit(idx, cpuc->active_mask);

        hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
        if (flags & PERF_EF_START)
                armpmu_start(event, PERF_EF_RELOAD);

        /* Propagate our changes to the userspace mapping. */
        perf_event_update_userpage(event);

out:
        perf_pmu_enable(event->pmu);
        return err;
}

static struct pmu pmu;

static int
validate_event(struct cpu_hw_events *cpuc,
               struct perf_event *event)
{
        struct hw_perf_event fake_event = event->hw;

        if (event->pmu != &pmu || event->state <= PERF_EVENT_STATE_OFF)
                return 1;

        return armpmu->get_event_idx(cpuc, &fake_event) >= 0;
}

static int
validate_group(struct perf_event *event)
{
        struct perf_event *sibling, *leader = event->group_leader;
        struct cpu_hw_events fake_pmu;

        memset(&fake_pmu, 0, sizeof(fake_pmu));

        if (!validate_event(&fake_pmu, leader))
                return -ENOSPC;

        list_for_each_entry(sibling, &leader->sibling_list, group_entry) {
                if (!validate_event(&fake_pmu, sibling))
                        return -ENOSPC;
        }

        if (!validate_event(&fake_pmu, event))
                return -ENOSPC;

        return 0;
}

static int
armpmu_reserve_hardware(void)
{
        int i, err = -ENODEV, irq;

        pmu_device = reserve_pmu(ARM_PMU_DEVICE_CPU);
        if (IS_ERR(pmu_device)) {
                pr_warning("unable to reserve pmu\n");
                return PTR_ERR(pmu_device);
        }

        init_pmu(ARM_PMU_DEVICE_CPU);

        if (pmu_device->num_resources < 1) {
                pr_err("no irqs for PMUs defined\n");
                return -ENODEV;
        }

        for (i = 0; i < pmu_device->num_resources; ++i) {
                irq = platform_get_irq(pmu_device, i);
                if (irq < 0)
                        continue;

                err = request_irq(irq, armpmu->handle_irq,
                                  IRQF_DISABLED | IRQF_NOBALANCING,
                                  "armpmu", NULL);
                if (err) {
                        pr_warning("unable to request IRQ%d for ARM perf "
                                "counters\n", irq);
                        break;
                }
        }

        if (err) {
                for (i = i - 1; i >= 0; --i) {
                        irq = platform_get_irq(pmu_device, i);
                        if (irq >= 0)
                                free_irq(irq, NULL);
                }
                release_pmu(pmu_device);
                pmu_device = NULL;
        }

        return err;
}

static void
armpmu_release_hardware(void)
{
        int i, irq;

        for (i = pmu_device->num_resources - 1; i >= 0; --i) {
                irq = platform_get_irq(pmu_device, i);
                if (irq >= 0)
                        free_irq(irq, NULL);
        }
        armpmu->stop();

        release_pmu(pmu_device);
        pmu_device = NULL;
}

static atomic_t active_events = ATOMIC_INIT(0);
static DEFINE_MUTEX(pmu_reserve_mutex);

static void
hw_perf_event_destroy(struct perf_event *event)
{
        if (atomic_dec_and_mutex_lock(&active_events, &pmu_reserve_mutex)) {
                armpmu_release_hardware();
                mutex_unlock(&pmu_reserve_mutex);
        }
}

static int
__hw_perf_event_init(struct perf_event *event)
{
        struct hw_perf_event *hwc = &event->hw;
        int mapping, err;

        /* Decode the generic type into an ARM event identifier. */
        if (PERF_TYPE_HARDWARE == event->attr.type) {
                mapping = armpmu_map_event(event->attr.config);
        } else if (PERF_TYPE_HW_CACHE == event->attr.type) {
                mapping = armpmu_map_cache_event(event->attr.config);
        } else if (PERF_TYPE_RAW == event->attr.type) {
                mapping = armpmu_map_raw_event(event->attr.config);
        } else {
                pr_debug("event type %x not supported\n", event->attr.type);
                return -EOPNOTSUPP;
        }

        if (mapping < 0) {
                pr_debug("event %x:%llx not supported\n", event->attr.type,
                         event->attr.config);
                return mapping;
        }

        /*
         * Check whether we need to exclude the counter from certain modes.
         * The ARM performance counters are on all of the time so if someone
         * has asked us for some excludes then we have to fail.
         */
        if (event->attr.exclude_kernel || event->attr.exclude_user ||
            event->attr.exclude_hv || event->attr.exclude_idle) {
                pr_debug("ARM performance counters do not support "
                         "mode exclusion\n");
                return -EPERM;
        }

        /*
         * We don't assign an index until we actually place the event onto
         * hardware. Use -1 to signify that we haven't decided where to put it
         * yet. For SMP systems, each core has it's own PMU so we can't do any
         * clever allocation or constraints checking at this point.
         */
        hwc->idx = -1;

        /*
         * Store the event encoding into the config_base field. config and
         * event_base are unused as the only 2 things we need to know are
         * the event mapping and the counter to use. The counter to use is
         * also the indx and the config_base is the event type.
         */
        hwc->config_base            = (unsigned long)mapping;
        hwc->config                 = 0;
        hwc->event_base             = 0;

        if (!hwc->sample_period) {
                hwc->sample_period  = armpmu->max_period;
                hwc->last_period    = hwc->sample_period;
                local64_set(&hwc->period_left, hwc->sample_period);
        }

        err = 0;
        if (event->group_leader != event) {
                err = validate_group(event);
                if (err)
                        return -EINVAL;
        }

        return err;
}

static int armpmu_event_init(struct perf_event *event)
{
        int err = 0;

        switch (event->attr.type) {
        case PERF_TYPE_RAW:
        case PERF_TYPE_HARDWARE:
        case PERF_TYPE_HW_CACHE:
                break;

        default:
                return -ENOENT;
        }

        if (!armpmu)
                return -ENODEV;

        event->destroy = hw_perf_event_destroy;

        if (!atomic_inc_not_zero(&active_events)) {
                if (atomic_read(&active_events) > armpmu->num_events) {
                        atomic_dec(&active_events);
                        return -ENOSPC;
                }

                mutex_lock(&pmu_reserve_mutex);
                if (atomic_read(&active_events) == 0) {
                        err = armpmu_reserve_hardware();
                }

                if (!err)
                        atomic_inc(&active_events);
                mutex_unlock(&pmu_reserve_mutex);
        }

        if (err)
                return err;

        err = __hw_perf_event_init(event);
        if (err)
                hw_perf_event_destroy(event);

        return err;
}

static void armpmu_enable(struct pmu *pmu)
{
        /* Enable all of the perf events on hardware. */
        int idx;
        struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);

        if (!armpmu)
                return;

        for (idx = 0; idx <= armpmu->num_events; ++idx) {
                struct perf_event *event = cpuc->events[idx];

                if (!event)
                        continue;

                armpmu->enable(&event->hw, idx);
        }

        armpmu->start();
}

static void armpmu_disable(struct pmu *pmu)
{
        if (armpmu)
                armpmu->stop();
}

static struct pmu pmu = {
        .pmu_enable     = armpmu_enable,
        .pmu_disable    = armpmu_disable,
        .event_init     = armpmu_event_init,
        .add            = armpmu_add,
        .del            = armpmu_del,
        .start          = armpmu_start,
        .stop           = armpmu_stop,
        .read           = armpmu_read,
};

/* Include the PMU-specific implementations. */
#include "perf_event_xscale.c"
#include "perf_event_v6.c"
#include "perf_event_v7.c"

static int __init
init_hw_perf_events(void)
{
        unsigned long cpuid = read_cpuid_id();
        unsigned long implementor = (cpuid & 0xFF000000) >> 24;
        unsigned long part_number = (cpuid & 0xFFF0);

        /* ARM Ltd CPUs. */
        if (0x41 == implementor) {
                switch (part_number) {
                case 0xB360:    /* ARM1136 */
                case 0xB560:    /* ARM1156 */
                case 0xB760:    /* ARM1176 */
                        armpmu = armv6pmu_init();
                        break;
                case 0xB020:    /* ARM11mpcore */
                        armpmu = armv6mpcore_pmu_init();
                        break;
                case 0xC080:    /* Cortex-A8 */
                        armpmu = armv7_a8_pmu_init();
                        break;
                case 0xC090:    /* Cortex-A9 */
                        armpmu = armv7_a9_pmu_init();
                        break;
                }
        /* Intel CPUs [xscale]. */
        } else if (0x69 == implementor) {
                part_number = (cpuid >> 13) & 0x7;
                switch (part_number) {
                case 1:
                        armpmu = xscale1pmu_init();
                        break;
                case 2:
                        armpmu = xscale2pmu_init();
                        break;
                }
        }

        if (armpmu) {
                pr_info("enabled with %s PMU driver, %d counters available\n",
                        armpmu->name, armpmu->num_events);
        } else {
                pr_info("no hardware support available\n");
        }

        perf_pmu_register(&pmu, "cpu", PERF_TYPE_RAW);

        return 0;
}
early_initcall(init_hw_perf_events);

/*
 * Callchain handling code.
 */

/*
 * The registers we're interested in are at the end of the variable
 * length saved register structure. The fp points at the end of this
 * structure so the address of this struct is:
 * (struct frame_tail *)(xxx->fp)-1
 *
 * This code has been adapted from the ARM OProfile support.
 */
struct frame_tail {
        struct frame_tail __user *fp;
        unsigned long sp;
        unsigned long lr;
} __attribute__((packed));

/*
 * Get the return address for a single stackframe and return a pointer to the
 * next frame tail.
 */
static struct frame_tail __user *
user_backtrace(struct frame_tail __user *tail,
               struct perf_callchain_entry *entry)
{
        struct frame_tail buftail;

        /* Also check accessibility of one struct frame_tail beyond */
        if (!access_ok(VERIFY_READ, tail, sizeof(buftail)))
                return NULL;
        if (__copy_from_user_inatomic(&buftail, tail, sizeof(buftail)))
                return NULL;

        perf_callchain_store(entry, buftail.lr);

        /*
         * Frame pointers should strictly progress back up the stack
         * (towards higher addresses).
         */
        if (tail + 1 >= buftail.fp)
                return NULL;

        return buftail.fp - 1;
}

void
perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
{
        struct frame_tail __user *tail;


        tail = (struct frame_tail __user *)regs->ARM_fp - 1;

        while (tail && !((unsigned long)tail & 0x3))
                tail = user_backtrace(tail, entry);
}

/*
 * Gets called by walk_stackframe() for every stackframe. This will be called
 * whist unwinding the stackframe and is like a subroutine return so we use
 * the PC.
 */
static int
callchain_trace(struct stackframe *fr,
                void *data)
{
        struct perf_callchain_entry *entry = data;
        perf_callchain_store(entry, fr->pc);
        return 0;
}

void
perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs)
{
        struct stackframe fr;

        fr.fp = regs->ARM_fp;
        fr.sp = regs->ARM_sp;
        fr.lr = regs->ARM_lr;
        fr.pc = regs->ARM_pc;
        walk_stackframe(&fr, callchain_trace, entry);
}