/*
 * Linux performance counter support for ARC700 series
 *
 * Copyright (C) 2013-2015 Synopsys, Inc. (www.synopsys.com)
 *
 * This code is inspired by the perf support of various other architectures.
 *
 * 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/errno.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/perf_event.h>
#include <linux/platform_device.h>
#include <asm/arcregs.h>
#include <asm/stacktrace.h>

struct arc_pmu {
        struct pmu      pmu;
        unsigned int    irq;
        int             n_counters;
        u64             max_period;
        int             ev_hw_idx[PERF_COUNT_ARC_HW_MAX];
};

struct arc_pmu_cpu {
        /*
         * 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(ARC_PERF_MAX_COUNTERS)];

        /*
         * The events that are active on the PMU for the given index.
         */
        struct perf_event *act_counter[ARC_PERF_MAX_COUNTERS];
};

struct arc_callchain_trace {
        int depth;
        void *perf_stuff;
};

static int callchain_trace(unsigned int addr, void *data)
{
        struct arc_callchain_trace *ctrl = data;
        struct perf_callchain_entry_ctx *entry = ctrl->perf_stuff;
        perf_callchain_store(entry, addr);

        if (ctrl->depth++ < 3)
                return 0;

        return -1;
}

void
perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
{
        struct arc_callchain_trace ctrl = {
                .depth = 0,
                .perf_stuff = entry,
        };

        arc_unwind_core(NULL, regs, callchain_trace, &ctrl);
}

void
perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
{
        /*
         * User stack can't be unwound trivially with kernel dwarf unwinder
         * So for now just record the user PC
         */
        perf_callchain_store(entry, instruction_pointer(regs));
}

static struct arc_pmu *arc_pmu;
static DEFINE_PER_CPU(struct arc_pmu_cpu, arc_pmu_cpu);

/* read counter #idx; note that counter# != event# on ARC! */
static uint64_t arc_pmu_read_counter(int idx)
{
        uint32_t tmp;
        uint64_t result;

        /*
         * ARC supports making 'snapshots' of the counters, so we don't
         * need to care about counters wrapping to 0 underneath our feet
         */
        write_aux_reg(ARC_REG_PCT_INDEX, idx);
        tmp = read_aux_reg(ARC_REG_PCT_CONTROL);
        write_aux_reg(ARC_REG_PCT_CONTROL, tmp | ARC_REG_PCT_CONTROL_SN);
        result = (uint64_t) (read_aux_reg(ARC_REG_PCT_SNAPH)) << 32;
        result |= read_aux_reg(ARC_REG_PCT_SNAPL);

        return result;
}

static void arc_perf_event_update(struct perf_event *event,
                                  struct hw_perf_event *hwc, int idx)
{
        uint64_t prev_raw_count = local64_read(&hwc->prev_count);
        uint64_t new_raw_count = arc_pmu_read_counter(idx);
        int64_t delta = new_raw_count - prev_raw_count;

        /*
         * We aren't afraid of hwc->prev_count changing beneath our feet
         * because there's no way for us to re-enter this function anytime.
         */
        local64_set(&hwc->prev_count, new_raw_count);
        local64_add(delta, &event->count);
        local64_sub(delta, &hwc->period_left);
}

static void arc_pmu_read(struct perf_event *event)
{
        arc_perf_event_update(event, &event->hw, event->hw.idx);
}

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

        cache_type      = (config >>  0) & 0xff;
        cache_op        = (config >>  8) & 0xff;
        cache_result    = (config >> 16) & 0xff;
        if (cache_type >= PERF_COUNT_HW_CACHE_MAX)
                return -EINVAL;
        if (cache_op >= PERF_COUNT_HW_CACHE_OP_MAX)
                return -EINVAL;
        if (cache_result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
                return -EINVAL;

        ret = arc_pmu_cache_map[cache_type][cache_op][cache_result];

        if (ret == CACHE_OP_UNSUPPORTED)
                return -ENOENT;

        pr_debug("init cache event: type/op/result %d/%d/%d with h/w %d \'%s\'\n",
                 cache_type, cache_op, cache_result, ret,
                 arc_pmu_ev_hw_map[ret]);

        return ret;
}

/* initializes hw_perf_event structure if event is supported */
static int arc_pmu_event_init(struct perf_event *event)
{
        struct hw_perf_event *hwc = &event->hw;
        int ret;

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

        hwc->config = 0;

        if (is_isa_arcv2()) {
                /* "exclude user" means "count only kernel" */
                if (event->attr.exclude_user)
                        hwc->config |= ARC_REG_PCT_CONFIG_KERN;

                /* "exclude kernel" means "count only user" */
                if (event->attr.exclude_kernel)
                        hwc->config |= ARC_REG_PCT_CONFIG_USER;
        }

        switch (event->attr.type) {
        case PERF_TYPE_HARDWARE:
                if (event->attr.config >= PERF_COUNT_HW_MAX)
                        return -ENOENT;
                if (arc_pmu->ev_hw_idx[event->attr.config] < 0)
                        return -ENOENT;
                hwc->config |= arc_pmu->ev_hw_idx[event->attr.config];
                pr_debug("init event %d with h/w %08x \'%s\'\n",
                         (int)event->attr.config, (int)hwc->config,
                         arc_pmu_ev_hw_map[event->attr.config]);
                return 0;

        case PERF_TYPE_HW_CACHE:
                ret = arc_pmu_cache_event(event->attr.config);
                if (ret < 0)
                        return ret;
                hwc->config |= arc_pmu->ev_hw_idx[ret];
                pr_debug("init cache event with h/w %08x \'%s\'\n",
                         (int)hwc->config, arc_pmu_ev_hw_map[ret]);
                return 0;
        default:
                return -ENOENT;
        }
}

/* starts all counters */
static void arc_pmu_enable(struct pmu *pmu)
{
        uint32_t tmp;
        tmp = read_aux_reg(ARC_REG_PCT_CONTROL);
        write_aux_reg(ARC_REG_PCT_CONTROL, (tmp & 0xffff0000) | 0x1);
}

/* stops all counters */
static void arc_pmu_disable(struct pmu *pmu)
{
        uint32_t tmp;
        tmp = read_aux_reg(ARC_REG_PCT_CONTROL);
        write_aux_reg(ARC_REG_PCT_CONTROL, (tmp & 0xffff0000) | 0x0);
}

static int arc_pmu_event_set_period(struct perf_event *event)
{
        struct hw_perf_event *hwc = &event->hw;
        s64 left = local64_read(&hwc->period_left);
        s64 period = hwc->sample_period;
        int idx = hwc->idx;
        int overflow = 0;
        u64 value;

        if (unlikely(left <= -period)) {
                /* left underflowed by more than period. */
                left = period;
                local64_set(&hwc->period_left, left);
                hwc->last_period = period;
                overflow = 1;
        } else  if (unlikely(left <= 0)) {
                /* left underflowed by less than period. */
                left += period;
                local64_set(&hwc->period_left, left);
                hwc->last_period = period;
                overflow = 1;
        }

        if (left > arc_pmu->max_period)
                left = arc_pmu->max_period;

        value = arc_pmu->max_period - left;
        local64_set(&hwc->prev_count, value);

        /* Select counter */
        write_aux_reg(ARC_REG_PCT_INDEX, idx);

        /* Write value */
        write_aux_reg(ARC_REG_PCT_COUNTL, (u32)value);
        write_aux_reg(ARC_REG_PCT_COUNTH, (value >> 32));

        perf_event_update_userpage(event);

        return overflow;
}

/*
 * Assigns hardware counter to hardware condition.
 * Note that there is no separate start/stop mechanism;
 * stopping is achieved by assigning the 'never' condition
 */
static void arc_pmu_start(struct perf_event *event, int flags)
{
        struct hw_perf_event *hwc = &event->hw;
        int idx = hwc->idx;

        if (WARN_ON_ONCE(idx == -1))
                return;

        if (flags & PERF_EF_RELOAD)
                WARN_ON_ONCE(!(hwc->state & PERF_HES_UPTODATE));

        hwc->state = 0;

        arc_pmu_event_set_period(event);

        /* Enable interrupt for this counter */
        if (is_sampling_event(event))
                write_aux_reg(ARC_REG_PCT_INT_CTRL,
                              read_aux_reg(ARC_REG_PCT_INT_CTRL) | (1 << idx));

        /* enable ARC pmu here */
        write_aux_reg(ARC_REG_PCT_INDEX, idx);          /* counter # */
        write_aux_reg(ARC_REG_PCT_CONFIG, hwc->config); /* condition */
}

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

        /* Disable interrupt for this counter */
        if (is_sampling_event(event)) {
                /*
                 * Reset interrupt flag by writing of 1. This is required
                 * to make sure pending interrupt was not left.
                 */
                write_aux_reg(ARC_REG_PCT_INT_ACT, 1 << idx);
                write_aux_reg(ARC_REG_PCT_INT_CTRL,
                              read_aux_reg(ARC_REG_PCT_INT_CTRL) & ~(1 << idx));
        }

        if (!(event->hw.state & PERF_HES_STOPPED)) {
                /* stop ARC pmu here */
                write_aux_reg(ARC_REG_PCT_INDEX, idx);

                /* condition code #0 is always "never" */
                write_aux_reg(ARC_REG_PCT_CONFIG, 0);

                event->hw.state |= PERF_HES_STOPPED;
        }

        if ((flags & PERF_EF_UPDATE) &&
            !(event->hw.state & PERF_HES_UPTODATE)) {
                arc_perf_event_update(event, &event->hw, idx);
                event->hw.state |= PERF_HES_UPTODATE;
        }
}

static void arc_pmu_del(struct perf_event *event, int flags)
{
        struct arc_pmu_cpu *pmu_cpu = this_cpu_ptr(&arc_pmu_cpu);

        arc_pmu_stop(event, PERF_EF_UPDATE);
        __clear_bit(event->hw.idx, pmu_cpu->used_mask);

        pmu_cpu->act_counter[event->hw.idx] = 0;

        perf_event_update_userpage(event);
}

/* allocate hardware counter and optionally start counting */
static int arc_pmu_add(struct perf_event *event, int flags)
{
        struct arc_pmu_cpu *pmu_cpu = this_cpu_ptr(&arc_pmu_cpu);
        struct hw_perf_event *hwc = &event->hw;
        int idx = hwc->idx;

        idx = ffz(pmu_cpu->used_mask[0]);
        if (idx == arc_pmu->n_counters)
                return -EAGAIN;

        __set_bit(idx, pmu_cpu->used_mask);
        hwc->idx = idx;

        write_aux_reg(ARC_REG_PCT_INDEX, idx);

        pmu_cpu->act_counter[idx] = event;

        if (is_sampling_event(event)) {
                /* Mimic full counter overflow as other arches do */
                write_aux_reg(ARC_REG_PCT_INT_CNTL, (u32)arc_pmu->max_period);
                write_aux_reg(ARC_REG_PCT_INT_CNTH,
                              (arc_pmu->max_period >> 32));
        }

        write_aux_reg(ARC_REG_PCT_CONFIG, 0);
        write_aux_reg(ARC_REG_PCT_COUNTL, 0);
        write_aux_reg(ARC_REG_PCT_COUNTH, 0);
        local64_set(&hwc->prev_count, 0);

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

        perf_event_update_userpage(event);

        return 0;
}

#ifdef CONFIG_ISA_ARCV2
static irqreturn_t arc_pmu_intr(int irq, void *dev)
{
        struct perf_sample_data data;
        struct arc_pmu_cpu *pmu_cpu = this_cpu_ptr(&arc_pmu_cpu);
        struct pt_regs *regs;
        unsigned int active_ints;
        int idx;

        arc_pmu_disable(&arc_pmu->pmu);

        active_ints = read_aux_reg(ARC_REG_PCT_INT_ACT);
        if (!active_ints)
                goto done;

        regs = get_irq_regs();

        do {
                struct perf_event *event;
                struct hw_perf_event *hwc;

                idx = __ffs(active_ints);

                /* Reset interrupt flag by writing of 1 */
                write_aux_reg(ARC_REG_PCT_INT_ACT, 1 << idx);

                /*
                 * On reset of "interrupt active" bit corresponding
                 * "interrupt enable" bit gets automatically reset as well.
                 * Now we need to re-enable interrupt for the counter.
                 */
                write_aux_reg(ARC_REG_PCT_INT_CTRL,
                        read_aux_reg(ARC_REG_PCT_INT_CTRL) | (1 << idx));

                event = pmu_cpu->act_counter[idx];
                hwc = &event->hw;

                WARN_ON_ONCE(hwc->idx != idx);

                arc_perf_event_update(event, &event->hw, event->hw.idx);
                perf_sample_data_init(&data, 0, hwc->last_period);
                if (arc_pmu_event_set_period(event)) {
                        if (perf_event_overflow(event, &data, regs))
                                arc_pmu_stop(event, 0);
                }

                active_ints &= ~(1U << idx);
        } while (active_ints);

done:
        arc_pmu_enable(&arc_pmu->pmu);

        return IRQ_HANDLED;
}
#else

static irqreturn_t arc_pmu_intr(int irq, void *dev)
{
        return IRQ_NONE;
}

#endif /* CONFIG_ISA_ARCV2 */

static void arc_cpu_pmu_irq_init(void *data)
{
        int irq = *(int *)data;

        enable_percpu_irq(irq, IRQ_TYPE_NONE);

        /* Clear all pending interrupt flags */
        write_aux_reg(ARC_REG_PCT_INT_ACT, 0xffffffff);
}

static int arc_pmu_device_probe(struct platform_device *pdev)
{
        struct arc_reg_pct_build pct_bcr;
        struct arc_reg_cc_build cc_bcr;
        int i, j, has_interrupts;
        int counter_size;       /* in bits */

        union cc_name {
                struct {
                        uint32_t word0, word1;
                        char sentinel;
                } indiv;
                char str[9];
        } cc_name;


        READ_BCR(ARC_REG_PCT_BUILD, pct_bcr);
        if (!pct_bcr.v) {
                pr_err("This core does not have performance counters!\n");
                return -ENODEV;
        }
        BUILD_BUG_ON(ARC_PERF_MAX_COUNTERS > 32);
        BUG_ON(pct_bcr.c > ARC_PERF_MAX_COUNTERS);

        READ_BCR(ARC_REG_CC_BUILD, cc_bcr);
        BUG_ON(!cc_bcr.v); /* Counters exist but No countable conditions ? */

        arc_pmu = devm_kzalloc(&pdev->dev, sizeof(struct arc_pmu), GFP_KERNEL);
        if (!arc_pmu)
                return -ENOMEM;

        has_interrupts = is_isa_arcv2() ? pct_bcr.i : 0;

        arc_pmu->n_counters = pct_bcr.c;
        counter_size = 32 + (pct_bcr.s << 4);

        arc_pmu->max_period = (1ULL << counter_size) / 2 - 1ULL;

        pr_info("ARC perf\t: %d counters (%d bits), %d conditions%s\n",
                arc_pmu->n_counters, counter_size, cc_bcr.c,
                has_interrupts ? ", [overflow IRQ support]":"");

        cc_name.str[8] = 0;
        for (i = 0; i < PERF_COUNT_ARC_HW_MAX; i++)
                arc_pmu->ev_hw_idx[i] = -1;

        /* loop thru all available h/w condition indexes */
        for (j = 0; j < cc_bcr.c; j++) {
                write_aux_reg(ARC_REG_CC_INDEX, j);
                cc_name.indiv.word0 = read_aux_reg(ARC_REG_CC_NAME0);
                cc_name.indiv.word1 = read_aux_reg(ARC_REG_CC_NAME1);

                /* See if it has been mapped to a perf event_id */
                for (i = 0; i < ARRAY_SIZE(arc_pmu_ev_hw_map); i++) {
                        if (arc_pmu_ev_hw_map[i] &&
                            !strcmp(arc_pmu_ev_hw_map[i], cc_name.str) &&
                            strlen(arc_pmu_ev_hw_map[i])) {
                                pr_debug("mapping perf event %2d to h/w event \'%8s\' (idx %d)\n",
                                         i, cc_name.str, j);
                                arc_pmu->ev_hw_idx[i] = j;
                        }
                }
        }

        arc_pmu->pmu = (struct pmu) {
                .pmu_enable     = arc_pmu_enable,
                .pmu_disable    = arc_pmu_disable,
                .event_init     = arc_pmu_event_init,
                .add            = arc_pmu_add,
                .del            = arc_pmu_del,
                .start          = arc_pmu_start,
                .stop           = arc_pmu_stop,
                .read           = arc_pmu_read,
        };

        if (has_interrupts) {
                int irq = platform_get_irq(pdev, 0);

                if (irq < 0) {
                        pr_err("Cannot get IRQ number for the platform\n");
                        return -ENODEV;
                }

                arc_pmu->irq = irq;

                /* intc map function ensures irq_set_percpu_devid() called */
                request_percpu_irq(irq, arc_pmu_intr, "ARC perf counters",
                                   this_cpu_ptr(&arc_pmu_cpu));

                on_each_cpu(arc_cpu_pmu_irq_init, &irq, 1);

        } else
                arc_pmu->pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT;

        return perf_pmu_register(&arc_pmu->pmu, pdev->name, PERF_TYPE_RAW);
}

#ifdef CONFIG_OF
static const struct of_device_id arc_pmu_match[] = {
        { .compatible = "snps,arc700-pct" },
        { .compatible = "snps,archs-pct" },
        {},
};
MODULE_DEVICE_TABLE(of, arc_pmu_match);
#endif

static struct platform_driver arc_pmu_driver = {
        .driver = {
                .name           = "arc-pct",
                .of_match_table = of_match_ptr(arc_pmu_match),
        },
        .probe          = arc_pmu_device_probe,
};

module_platform_driver(arc_pmu_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Mischa Jonker <mjonker@synopsys.com>");
MODULE_DESCRIPTION("ARC PMU driver");