/* Copyright (c) 2015-2017 The Linux Foundation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 and
 * only version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */
#include <linux/acpi.h>
#include <linux/bitops.h>
#include <linux/bug.h>
#include <linux/cpuhotplug.h>
#include <linux/cpumask.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/percpu.h>
#include <linux/perf_event.h>
#include <linux/platform_device.h>
#include <linux/smp.h>
#include <linux/spinlock.h>
#include <linux/sysfs.h>
#include <linux/types.h>

#include <asm/barrier.h>
#include <asm/local64.h>
#include <asm/sysreg.h>

#define MAX_L2_CTRS             9

#define L2PMCR_NUM_EV_SHIFT     11
#define L2PMCR_NUM_EV_MASK      0x1F

#define L2PMCR                  0x400
#define L2PMCNTENCLR            0x403
#define L2PMCNTENSET            0x404
#define L2PMINTENCLR            0x405
#define L2PMINTENSET            0x406
#define L2PMOVSCLR              0x407
#define L2PMOVSSET              0x408
#define L2PMCCNTCR              0x409
#define L2PMCCNTR               0x40A
#define L2PMCCNTSR              0x40C
#define L2PMRESR                0x410
#define IA_L2PMXEVCNTCR_BASE    0x420
#define IA_L2PMXEVCNTR_BASE     0x421
#define IA_L2PMXEVFILTER_BASE   0x423
#define IA_L2PMXEVTYPER_BASE    0x424

#define IA_L2_REG_OFFSET        0x10

#define L2PMXEVFILTER_SUFILTER_ALL      0x000E0000
#define L2PMXEVFILTER_ORGFILTER_IDINDEP 0x00000004
#define L2PMXEVFILTER_ORGFILTER_ALL     0x00000003

#define L2EVTYPER_REG_SHIFT     3

#define L2PMRESR_GROUP_BITS     8
#define L2PMRESR_GROUP_MASK     GENMASK(7, 0)

#define L2CYCLE_CTR_BIT         31
#define L2CYCLE_CTR_RAW_CODE    0xFE

#define L2PMCR_RESET_ALL        0x6
#define L2PMCR_COUNTERS_ENABLE  0x1
#define L2PMCR_COUNTERS_DISABLE 0x0

#define L2PMRESR_EN             BIT_ULL(63)

#define L2_EVT_MASK             0x00000FFF
#define L2_EVT_CODE_MASK        0x00000FF0
#define L2_EVT_GRP_MASK         0x0000000F
#define L2_EVT_CODE_SHIFT       4
#define L2_EVT_GRP_SHIFT        0

#define L2_EVT_CODE(event)   (((event) & L2_EVT_CODE_MASK) >> L2_EVT_CODE_SHIFT)
#define L2_EVT_GROUP(event)  (((event) & L2_EVT_GRP_MASK) >> L2_EVT_GRP_SHIFT)

#define L2_EVT_GROUP_MAX        7

#define L2_COUNTER_RELOAD       BIT_ULL(31)
#define L2_CYCLE_COUNTER_RELOAD BIT_ULL(63)

#define L2CPUSRSELR_EL1         sys_reg(3, 3, 15, 0, 6)
#define L2CPUSRDR_EL1           sys_reg(3, 3, 15, 0, 7)

#define reg_idx(reg, i)         (((i) * IA_L2_REG_OFFSET) + reg##_BASE)

/*
 * Events
 */
#define L2_EVENT_CYCLES                    0xfe
#define L2_EVENT_DCACHE_OPS                0x400
#define L2_EVENT_ICACHE_OPS                0x401
#define L2_EVENT_TLBI                      0x402
#define L2_EVENT_BARRIERS                  0x403
#define L2_EVENT_TOTAL_READS               0x405
#define L2_EVENT_TOTAL_WRITES              0x406
#define L2_EVENT_TOTAL_REQUESTS            0x407
#define L2_EVENT_LDREX                     0x420
#define L2_EVENT_STREX                     0x421
#define L2_EVENT_CLREX                     0x422

static DEFINE_RAW_SPINLOCK(l2_access_lock);

/**
 * set_l2_indirect_reg: write value to an L2 register
 * @reg: Address of L2 register.
 * @value: Value to be written to register.
 *
 * Use architecturally required barriers for ordering between system register
 * accesses
 */
static void set_l2_indirect_reg(u64 reg, u64 val)
{
        unsigned long flags;

        raw_spin_lock_irqsave(&l2_access_lock, flags);
        write_sysreg_s(reg, L2CPUSRSELR_EL1);
        isb();
        write_sysreg_s(val, L2CPUSRDR_EL1);
        isb();
        raw_spin_unlock_irqrestore(&l2_access_lock, flags);
}

/**
 * get_l2_indirect_reg: read an L2 register value
 * @reg: Address of L2 register.
 *
 * Use architecturally required barriers for ordering between system register
 * accesses
 */
static u64 get_l2_indirect_reg(u64 reg)
{
        u64 val;
        unsigned long flags;

        raw_spin_lock_irqsave(&l2_access_lock, flags);
        write_sysreg_s(reg, L2CPUSRSELR_EL1);
        isb();
        val = read_sysreg_s(L2CPUSRDR_EL1);
        raw_spin_unlock_irqrestore(&l2_access_lock, flags);

        return val;
}

struct cluster_pmu;

/*
 * Aggregate PMU. Implements the core pmu functions and manages
 * the hardware PMUs.
 */
struct l2cache_pmu {
        struct hlist_node node;
        u32 num_pmus;
        struct pmu pmu;
        int num_counters;
        cpumask_t cpumask;
        struct platform_device *pdev;
        struct cluster_pmu * __percpu *pmu_cluster;
        struct list_head clusters;
};

/*
 * The cache is made up of one or more clusters, each cluster has its own PMU.
 * Each cluster is associated with one or more CPUs.
 * This structure represents one of the hardware PMUs.
 *
 * Events can be envisioned as a 2-dimensional array. Each column represents
 * a group of events. There are 8 groups. Only one entry from each
 * group can be in use at a time.
 *
 * Events are specified as 0xCCG, where CC is 2 hex digits specifying
 * the code (array row) and G specifies the group (column).
 *
 * In addition there is a cycle counter event specified by L2CYCLE_CTR_RAW_CODE
 * which is outside the above scheme.
 */
struct cluster_pmu {
        struct list_head next;
        struct perf_event *events[MAX_L2_CTRS];
        struct l2cache_pmu *l2cache_pmu;
        DECLARE_BITMAP(used_counters, MAX_L2_CTRS);
        DECLARE_BITMAP(used_groups, L2_EVT_GROUP_MAX + 1);
        int irq;
        int cluster_id;
        /* The CPU that is used for collecting events on this cluster */
        int on_cpu;
        /* All the CPUs associated with this cluster */
        cpumask_t cluster_cpus;
        spinlock_t pmu_lock;
};

#define to_l2cache_pmu(p) (container_of(p, struct l2cache_pmu, pmu))

static u32 l2_cycle_ctr_idx;
static u32 l2_counter_present_mask;

static inline u32 idx_to_reg_bit(u32 idx)
{
        if (idx == l2_cycle_ctr_idx)
                return BIT(L2CYCLE_CTR_BIT);

        return BIT(idx);
}

static inline struct cluster_pmu *get_cluster_pmu(
        struct l2cache_pmu *l2cache_pmu, int cpu)
{
        return *per_cpu_ptr(l2cache_pmu->pmu_cluster, cpu);
}

static void cluster_pmu_reset(void)
{
        /* Reset all counters */
        set_l2_indirect_reg(L2PMCR, L2PMCR_RESET_ALL);
        set_l2_indirect_reg(L2PMCNTENCLR, l2_counter_present_mask);
        set_l2_indirect_reg(L2PMINTENCLR, l2_counter_present_mask);
        set_l2_indirect_reg(L2PMOVSCLR, l2_counter_present_mask);
}

static inline void cluster_pmu_enable(void)
{
        set_l2_indirect_reg(L2PMCR, L2PMCR_COUNTERS_ENABLE);
}

static inline void cluster_pmu_disable(void)
{
        set_l2_indirect_reg(L2PMCR, L2PMCR_COUNTERS_DISABLE);
}

static inline void cluster_pmu_counter_set_value(u32 idx, u64 value)
{
        if (idx == l2_cycle_ctr_idx)
                set_l2_indirect_reg(L2PMCCNTR, value);
        else
                set_l2_indirect_reg(reg_idx(IA_L2PMXEVCNTR, idx), value);
}

static inline u64 cluster_pmu_counter_get_value(u32 idx)
{
        u64 value;

        if (idx == l2_cycle_ctr_idx)
                value = get_l2_indirect_reg(L2PMCCNTR);
        else
                value = get_l2_indirect_reg(reg_idx(IA_L2PMXEVCNTR, idx));

        return value;
}

static inline void cluster_pmu_counter_enable(u32 idx)
{
        set_l2_indirect_reg(L2PMCNTENSET, idx_to_reg_bit(idx));
}

static inline void cluster_pmu_counter_disable(u32 idx)
{
        set_l2_indirect_reg(L2PMCNTENCLR, idx_to_reg_bit(idx));
}

static inline void cluster_pmu_counter_enable_interrupt(u32 idx)
{
        set_l2_indirect_reg(L2PMINTENSET, idx_to_reg_bit(idx));
}

static inline void cluster_pmu_counter_disable_interrupt(u32 idx)
{
        set_l2_indirect_reg(L2PMINTENCLR, idx_to_reg_bit(idx));
}

static inline void cluster_pmu_set_evccntcr(u32 val)
{
        set_l2_indirect_reg(L2PMCCNTCR, val);
}

static inline void cluster_pmu_set_evcntcr(u32 ctr, u32 val)
{
        set_l2_indirect_reg(reg_idx(IA_L2PMXEVCNTCR, ctr), val);
}

static inline void cluster_pmu_set_evtyper(u32 ctr, u32 val)
{
        set_l2_indirect_reg(reg_idx(IA_L2PMXEVTYPER, ctr), val);
}

static void cluster_pmu_set_resr(struct cluster_pmu *cluster,
                               u32 event_group, u32 event_cc)
{
        u64 field;
        u64 resr_val;
        u32 shift;
        unsigned long flags;

        shift = L2PMRESR_GROUP_BITS * event_group;
        field = ((u64)(event_cc & L2PMRESR_GROUP_MASK) << shift);

        spin_lock_irqsave(&cluster->pmu_lock, flags);

        resr_val = get_l2_indirect_reg(L2PMRESR);
        resr_val &= ~(L2PMRESR_GROUP_MASK << shift);
        resr_val |= field;
        resr_val |= L2PMRESR_EN;
        set_l2_indirect_reg(L2PMRESR, resr_val);

        spin_unlock_irqrestore(&cluster->pmu_lock, flags);
}

/*
 * Hardware allows filtering of events based on the originating
 * CPU. Turn this off by setting filter bits to allow events from
 * all CPUS, subunits and ID independent events in this cluster.
 */
static inline void cluster_pmu_set_evfilter_sys_mode(u32 ctr)
{
        u32 val =  L2PMXEVFILTER_SUFILTER_ALL |
                   L2PMXEVFILTER_ORGFILTER_IDINDEP |
                   L2PMXEVFILTER_ORGFILTER_ALL;

        set_l2_indirect_reg(reg_idx(IA_L2PMXEVFILTER, ctr), val);
}

static inline u32 cluster_pmu_getreset_ovsr(void)
{
        u32 result = get_l2_indirect_reg(L2PMOVSSET);

        set_l2_indirect_reg(L2PMOVSCLR, result);
        return result;
}

static inline bool cluster_pmu_has_overflowed(u32 ovsr)
{
        return !!(ovsr & l2_counter_present_mask);
}

static inline bool cluster_pmu_counter_has_overflowed(u32 ovsr, u32 idx)
{
        return !!(ovsr & idx_to_reg_bit(idx));
}

static void l2_cache_event_update(struct perf_event *event)
{
        struct hw_perf_event *hwc = &event->hw;
        u64 delta, prev, now;
        u32 idx = hwc->idx;

        do {
                prev = local64_read(&hwc->prev_count);
                now = cluster_pmu_counter_get_value(idx);
        } while (local64_cmpxchg(&hwc->prev_count, prev, now) != prev);

        /*
         * The cycle counter is 64-bit, but all other counters are
         * 32-bit, and we must handle 32-bit overflow explicitly.
         */
        delta = now - prev;
        if (idx != l2_cycle_ctr_idx)
                delta &= 0xffffffff;

        local64_add(delta, &event->count);
}

static void l2_cache_cluster_set_period(struct cluster_pmu *cluster,
                                       struct hw_perf_event *hwc)
{
        u32 idx = hwc->idx;
        u64 new;

        /*
         * We limit the max period to half the max counter value so
         * that even in the case of extreme interrupt latency the
         * counter will (hopefully) not wrap past its initial value.
         */
        if (idx == l2_cycle_ctr_idx)
                new = L2_CYCLE_COUNTER_RELOAD;
        else
                new = L2_COUNTER_RELOAD;

        local64_set(&hwc->prev_count, new);
        cluster_pmu_counter_set_value(idx, new);
}

static int l2_cache_get_event_idx(struct cluster_pmu *cluster,
                                   struct perf_event *event)
{
        struct hw_perf_event *hwc = &event->hw;
        int idx;
        int num_ctrs = cluster->l2cache_pmu->num_counters - 1;
        unsigned int group;

        if (hwc->config_base == L2CYCLE_CTR_RAW_CODE) {
                if (test_and_set_bit(l2_cycle_ctr_idx, cluster->used_counters))
                        return -EAGAIN;

                return l2_cycle_ctr_idx;
        }

        idx = find_first_zero_bit(cluster->used_counters, num_ctrs);
        if (idx == num_ctrs)
                /* The counters are all in use. */
                return -EAGAIN;

        /*
         * Check for column exclusion: event column already in use by another
         * event. This is for events which are not in the same group.
         * Conflicting events in the same group are detected in event_init.
         */
        group = L2_EVT_GROUP(hwc->config_base);
        if (test_bit(group, cluster->used_groups))
                return -EAGAIN;

        set_bit(idx, cluster->used_counters);
        set_bit(group, cluster->used_groups);

        return idx;
}

static void l2_cache_clear_event_idx(struct cluster_pmu *cluster,
                                      struct perf_event *event)
{
        struct hw_perf_event *hwc = &event->hw;
        int idx = hwc->idx;

        clear_bit(idx, cluster->used_counters);
        if (hwc->config_base != L2CYCLE_CTR_RAW_CODE)
                clear_bit(L2_EVT_GROUP(hwc->config_base), cluster->used_groups);
}

static irqreturn_t l2_cache_handle_irq(int irq_num, void *data)
{
        struct cluster_pmu *cluster = data;
        int num_counters = cluster->l2cache_pmu->num_counters;
        u32 ovsr;
        int idx;

        ovsr = cluster_pmu_getreset_ovsr();
        if (!cluster_pmu_has_overflowed(ovsr))
                return IRQ_NONE;

        for_each_set_bit(idx, cluster->used_counters, num_counters) {
                struct perf_event *event = cluster->events[idx];
                struct hw_perf_event *hwc;

                if (WARN_ON_ONCE(!event))
                        continue;

                if (!cluster_pmu_counter_has_overflowed(ovsr, idx))
                        continue;

                l2_cache_event_update(event);
                hwc = &event->hw;

                l2_cache_cluster_set_period(cluster, hwc);
        }

        return IRQ_HANDLED;
}

/*
 * Implementation of abstract pmu functionality required by
 * the core perf events code.
 */

static void l2_cache_pmu_enable(struct pmu *pmu)
{
        /*
         * Although there is only one PMU (per socket) controlling multiple
         * physical PMUs (per cluster), because we do not support per-task mode
         * each event is associated with a CPU. Each event has pmu_enable
         * called on its CPU, so here it is only necessary to enable the
         * counters for the current CPU.
         */

        cluster_pmu_enable();
}

static void l2_cache_pmu_disable(struct pmu *pmu)
{
        cluster_pmu_disable();
}

static int l2_cache_event_init(struct perf_event *event)
{
        struct hw_perf_event *hwc = &event->hw;
        struct cluster_pmu *cluster;
        struct perf_event *sibling;
        struct l2cache_pmu *l2cache_pmu;

        if (event->attr.type != event->pmu->type)
                return -ENOENT;

        l2cache_pmu = to_l2cache_pmu(event->pmu);

        if (hwc->sample_period) {
                dev_dbg_ratelimited(&l2cache_pmu->pdev->dev,
                                    "Sampling not supported\n");
                return -EOPNOTSUPP;
        }

        if (event->cpu < 0) {
                dev_dbg_ratelimited(&l2cache_pmu->pdev->dev,
                                    "Per-task mode not supported\n");
                return -EOPNOTSUPP;
        }

        /* We cannot filter accurately so we just don't allow it. */
        if (event->attr.exclude_user || event->attr.exclude_kernel ||
            event->attr.exclude_hv || event->attr.exclude_idle) {
                dev_dbg_ratelimited(&l2cache_pmu->pdev->dev,
                                    "Can't exclude execution levels\n");
                return -EOPNOTSUPP;
        }

        if (((L2_EVT_GROUP(event->attr.config) > L2_EVT_GROUP_MAX) ||
             ((event->attr.config & ~L2_EVT_MASK) != 0)) &&
            (event->attr.config != L2CYCLE_CTR_RAW_CODE)) {
                dev_dbg_ratelimited(&l2cache_pmu->pdev->dev,
                                    "Invalid config %llx\n",
                                    event->attr.config);
                return -EINVAL;
        }

        /* Don't allow groups with mixed PMUs, except for s/w events */
        if (event->group_leader->pmu != event->pmu &&
            !is_software_event(event->group_leader)) {
                dev_dbg_ratelimited(&l2cache_pmu->pdev->dev,
                         "Can't create mixed PMU group\n");
                return -EINVAL;
        }

        for_each_sibling_event(sibling, event->group_leader) {
                if (sibling->pmu != event->pmu &&
                    !is_software_event(sibling)) {
                        dev_dbg_ratelimited(&l2cache_pmu->pdev->dev,
                                 "Can't create mixed PMU group\n");
                        return -EINVAL;
                }
        }

        cluster = get_cluster_pmu(l2cache_pmu, event->cpu);
        if (!cluster) {
                /* CPU has not been initialised */
                dev_dbg_ratelimited(&l2cache_pmu->pdev->dev,
                        "CPU%d not associated with L2 cluster\n", event->cpu);
                return -EINVAL;
        }

        /* Ensure all events in a group are on the same cpu */
        if ((event->group_leader != event) &&
            (cluster->on_cpu != event->group_leader->cpu)) {
                dev_dbg_ratelimited(&l2cache_pmu->pdev->dev,
                         "Can't create group on CPUs %d and %d",
                         event->cpu, event->group_leader->cpu);
                return -EINVAL;
        }

        if ((event != event->group_leader) &&
            !is_software_event(event->group_leader) &&
            (L2_EVT_GROUP(event->group_leader->attr.config) ==
             L2_EVT_GROUP(event->attr.config))) {
                dev_dbg_ratelimited(&l2cache_pmu->pdev->dev,
                         "Column exclusion: conflicting events %llx %llx\n",
                       event->group_leader->attr.config,
                       event->attr.config);
                return -EINVAL;
        }

        for_each_sibling_event(sibling, event->group_leader) {
                if ((sibling != event) &&
                    !is_software_event(sibling) &&
                    (L2_EVT_GROUP(sibling->attr.config) ==
                     L2_EVT_GROUP(event->attr.config))) {
                        dev_dbg_ratelimited(&l2cache_pmu->pdev->dev,
                             "Column exclusion: conflicting events %llx %llx\n",
                                            sibling->attr.config,
                                            event->attr.config);
                        return -EINVAL;
                }
        }

        hwc->idx = -1;
        hwc->config_base = event->attr.config;

        /*
         * Ensure all events are on the same cpu so all events are in the
         * same cpu context, to avoid races on pmu_enable etc.
         */
        event->cpu = cluster->on_cpu;

        return 0;
}

static void l2_cache_event_start(struct perf_event *event, int flags)
{
        struct cluster_pmu *cluster;
        struct hw_perf_event *hwc = &event->hw;
        int idx = hwc->idx;
        u32 config;
        u32 event_cc, event_group;

        hwc->state = 0;

        cluster = get_cluster_pmu(to_l2cache_pmu(event->pmu), event->cpu);

        l2_cache_cluster_set_period(cluster, hwc);

        if (hwc->config_base == L2CYCLE_CTR_RAW_CODE) {
                cluster_pmu_set_evccntcr(0);
        } else {
                config = hwc->config_base;
                event_cc    = L2_EVT_CODE(config);
                event_group = L2_EVT_GROUP(config);

                cluster_pmu_set_evcntcr(idx, 0);
                cluster_pmu_set_evtyper(idx, event_group);
                cluster_pmu_set_resr(cluster, event_group, event_cc);
                cluster_pmu_set_evfilter_sys_mode(idx);
        }

        cluster_pmu_counter_enable_interrupt(idx);
        cluster_pmu_counter_enable(idx);
}

static void l2_cache_event_stop(struct perf_event *event, int flags)
{
        struct hw_perf_event *hwc = &event->hw;
        int idx = hwc->idx;

        if (hwc->state & PERF_HES_STOPPED)
                return;

        cluster_pmu_counter_disable_interrupt(idx);
        cluster_pmu_counter_disable(idx);

        if (flags & PERF_EF_UPDATE)
                l2_cache_event_update(event);
        hwc->state |= PERF_HES_STOPPED | PERF_HES_UPTODATE;
}

static int l2_cache_event_add(struct perf_event *event, int flags)
{
        struct hw_perf_event *hwc = &event->hw;
        int idx;
        int err = 0;
        struct cluster_pmu *cluster;

        cluster = get_cluster_pmu(to_l2cache_pmu(event->pmu), event->cpu);

        idx = l2_cache_get_event_idx(cluster, event);
        if (idx < 0)
                return idx;

        hwc->idx = idx;
        hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
        cluster->events[idx] = event;
        local64_set(&hwc->prev_count, 0);

        if (flags & PERF_EF_START)
                l2_cache_event_start(event, flags);

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

        return err;
}

static void l2_cache_event_del(struct perf_event *event, int flags)
{
        struct hw_perf_event *hwc = &event->hw;
        struct cluster_pmu *cluster;
        int idx = hwc->idx;

        cluster = get_cluster_pmu(to_l2cache_pmu(event->pmu), event->cpu);

        l2_cache_event_stop(event, flags | PERF_EF_UPDATE);
        cluster->events[idx] = NULL;
        l2_cache_clear_event_idx(cluster, event);

        perf_event_update_userpage(event);
}

static void l2_cache_event_read(struct perf_event *event)
{
        l2_cache_event_update(event);
}

static ssize_t l2_cache_pmu_cpumask_show(struct device *dev,
                                         struct device_attribute *attr,
                                         char *buf)
{
        struct l2cache_pmu *l2cache_pmu = to_l2cache_pmu(dev_get_drvdata(dev));

        return cpumap_print_to_pagebuf(true, buf, &l2cache_pmu->cpumask);
}

static struct device_attribute l2_cache_pmu_cpumask_attr =
                __ATTR(cpumask, S_IRUGO, l2_cache_pmu_cpumask_show, NULL);

static struct attribute *l2_cache_pmu_cpumask_attrs[] = {
        &l2_cache_pmu_cpumask_attr.attr,
        NULL,
};

static struct attribute_group l2_cache_pmu_cpumask_group = {
        .attrs = l2_cache_pmu_cpumask_attrs,
};

/* CCG format for perf RAW codes. */
PMU_FORMAT_ATTR(l2_code,   "config:4-11");
PMU_FORMAT_ATTR(l2_group,  "config:0-3");
PMU_FORMAT_ATTR(event,     "config:0-11");

static struct attribute *l2_cache_pmu_formats[] = {
        &format_attr_l2_code.attr,
        &format_attr_l2_group.attr,
        &format_attr_event.attr,
        NULL,
};

static struct attribute_group l2_cache_pmu_format_group = {
        .name = "format",
        .attrs = l2_cache_pmu_formats,
};

static ssize_t l2cache_pmu_event_show(struct device *dev,
                                      struct device_attribute *attr, char *page)
{
        struct perf_pmu_events_attr *pmu_attr;

        pmu_attr = container_of(attr, struct perf_pmu_events_attr, attr);
        return sprintf(page, "event=0x%02llx\n", pmu_attr->id);
}

#define L2CACHE_EVENT_ATTR(_name, _id)                                       \
        (&((struct perf_pmu_events_attr[]) {                                 \
                { .attr = __ATTR(_name, 0444, l2cache_pmu_event_show, NULL), \
                  .id = _id, }                                               \
        })[0].attr.attr)

static struct attribute *l2_cache_pmu_events[] = {
        L2CACHE_EVENT_ATTR(cycles, L2_EVENT_CYCLES),
        L2CACHE_EVENT_ATTR(dcache-ops, L2_EVENT_DCACHE_OPS),
        L2CACHE_EVENT_ATTR(icache-ops, L2_EVENT_ICACHE_OPS),
        L2CACHE_EVENT_ATTR(tlbi, L2_EVENT_TLBI),
        L2CACHE_EVENT_ATTR(barriers, L2_EVENT_BARRIERS),
        L2CACHE_EVENT_ATTR(total-reads, L2_EVENT_TOTAL_READS),
        L2CACHE_EVENT_ATTR(total-writes, L2_EVENT_TOTAL_WRITES),
        L2CACHE_EVENT_ATTR(total-requests, L2_EVENT_TOTAL_REQUESTS),
        L2CACHE_EVENT_ATTR(ldrex, L2_EVENT_LDREX),
        L2CACHE_EVENT_ATTR(strex, L2_EVENT_STREX),
        L2CACHE_EVENT_ATTR(clrex, L2_EVENT_CLREX),
        NULL
};

static struct attribute_group l2_cache_pmu_events_group = {
        .name = "events",
        .attrs = l2_cache_pmu_events,
};

static const struct attribute_group *l2_cache_pmu_attr_grps[] = {
        &l2_cache_pmu_format_group,
        &l2_cache_pmu_cpumask_group,
        &l2_cache_pmu_events_group,
        NULL,
};

/*
 * Generic device handlers
 */

static const struct acpi_device_id l2_cache_pmu_acpi_match[] = {
        { "QCOM8130", },
        { }
};

static int get_num_counters(void)
{
        int val;

        val = get_l2_indirect_reg(L2PMCR);

        /*
         * Read number of counters from L2PMCR and add 1
         * for the cycle counter.
         */
        return ((val >> L2PMCR_NUM_EV_SHIFT) & L2PMCR_NUM_EV_MASK) + 1;
}

static struct cluster_pmu *l2_cache_associate_cpu_with_cluster(
        struct l2cache_pmu *l2cache_pmu, int cpu)
{
        u64 mpidr;
        int cpu_cluster_id;
        struct cluster_pmu *cluster = NULL;

        /*
         * This assumes that the cluster_id is in MPIDR[aff1] for
         * single-threaded cores, and MPIDR[aff2] for multi-threaded
         * cores. This logic will have to be updated if this changes.
         */
        mpidr = read_cpuid_mpidr();
        if (mpidr & MPIDR_MT_BITMASK)
                cpu_cluster_id = MPIDR_AFFINITY_LEVEL(mpidr, 2);
        else
                cpu_cluster_id = MPIDR_AFFINITY_LEVEL(mpidr, 1);

        list_for_each_entry(cluster, &l2cache_pmu->clusters, next) {
                if (cluster->cluster_id != cpu_cluster_id)
                        continue;

                dev_info(&l2cache_pmu->pdev->dev,
                         "CPU%d associated with cluster %d\n", cpu,
                         cluster->cluster_id);
                cpumask_set_cpu(cpu, &cluster->cluster_cpus);
                *per_cpu_ptr(l2cache_pmu->pmu_cluster, cpu) = cluster;
                break;
        }

        return cluster;
}

static int l2cache_pmu_online_cpu(unsigned int cpu, struct hlist_node *node)
{
        struct cluster_pmu *cluster;
        struct l2cache_pmu *l2cache_pmu;

        l2cache_pmu = hlist_entry_safe(node, struct l2cache_pmu, node);
        cluster = get_cluster_pmu(l2cache_pmu, cpu);
        if (!cluster) {
                /* First time this CPU has come online */
                cluster = l2_cache_associate_cpu_with_cluster(l2cache_pmu, cpu);
                if (!cluster) {
                        /* Only if broken firmware doesn't list every cluster */
                        WARN_ONCE(1, "No L2 cache cluster for CPU%d\n", cpu);
                        return 0;
                }
        }

        /* If another CPU is managing this cluster, we're done */
        if (cluster->on_cpu != -1)
                return 0;

        /*
         * All CPUs on this cluster were down, use this one.
         * Reset to put it into sane state.
         */
        cluster->on_cpu = cpu;
        cpumask_set_cpu(cpu, &l2cache_pmu->cpumask);
        cluster_pmu_reset();

        WARN_ON(irq_set_affinity(cluster->irq, cpumask_of(cpu)));
        enable_irq(cluster->irq);

        return 0;
}

static int l2cache_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node)
{
        struct cluster_pmu *cluster;
        struct l2cache_pmu *l2cache_pmu;
        cpumask_t cluster_online_cpus;
        unsigned int target;

        l2cache_pmu = hlist_entry_safe(node, struct l2cache_pmu, node);
        cluster = get_cluster_pmu(l2cache_pmu, cpu);
        if (!cluster)
                return 0;

        /* If this CPU is not managing the cluster, we're done */
        if (cluster->on_cpu != cpu)
                return 0;

        /* Give up ownership of cluster */
        cpumask_clear_cpu(cpu, &l2cache_pmu->cpumask);
        cluster->on_cpu = -1;

        /* Any other CPU for this cluster which is still online */
        cpumask_and(&cluster_online_cpus, &cluster->cluster_cpus,
                    cpu_online_mask);
        target = cpumask_any_but(&cluster_online_cpus, cpu);
        if (target >= nr_cpu_ids) {
                disable_irq(cluster->irq);
                return 0;
        }

        perf_pmu_migrate_context(&l2cache_pmu->pmu, cpu, target);
        cluster->on_cpu = target;
        cpumask_set_cpu(target, &l2cache_pmu->cpumask);
        WARN_ON(irq_set_affinity(cluster->irq, cpumask_of(target)));

        return 0;
}

static int l2_cache_pmu_probe_cluster(struct device *dev, void *data)
{
        struct platform_device *pdev = to_platform_device(dev->parent);
        struct platform_device *sdev = to_platform_device(dev);
        struct l2cache_pmu *l2cache_pmu = data;
        struct cluster_pmu *cluster;
        struct acpi_device *device;
        unsigned long fw_cluster_id;
        int err;
        int irq;

        if (acpi_bus_get_device(ACPI_HANDLE(dev), &device))
                return -ENODEV;

        if (kstrtoul(device->pnp.unique_id, 10, &fw_cluster_id) < 0) {
                dev_err(&pdev->dev, "unable to read ACPI uid\n");
                return -ENODEV;
        }

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

        INIT_LIST_HEAD(&cluster->next);
        list_add(&cluster->next, &l2cache_pmu->clusters);
        cluster->cluster_id = fw_cluster_id;

        irq = platform_get_irq(sdev, 0);
        if (irq < 0) {
                dev_err(&pdev->dev,
                        "Failed to get valid irq for cluster %ld\n",
                        fw_cluster_id);
                return irq;
        }
        irq_set_status_flags(irq, IRQ_NOAUTOEN);
        cluster->irq = irq;

        cluster->l2cache_pmu = l2cache_pmu;
        cluster->on_cpu = -1;

        err = devm_request_irq(&pdev->dev, irq, l2_cache_handle_irq,
                               IRQF_NOBALANCING | IRQF_NO_THREAD,
                               "l2-cache-pmu", cluster);
        if (err) {
                dev_err(&pdev->dev,
                        "Unable to request IRQ%d for L2 PMU counters\n", irq);
                return err;
        }

        dev_info(&pdev->dev,
                "Registered L2 cache PMU cluster %ld\n", fw_cluster_id);

        spin_lock_init(&cluster->pmu_lock);

        l2cache_pmu->num_pmus++;

        return 0;
}

static int l2_cache_pmu_probe(struct platform_device *pdev)
{
        int err;
        struct l2cache_pmu *l2cache_pmu;

        l2cache_pmu =
                devm_kzalloc(&pdev->dev, sizeof(*l2cache_pmu), GFP_KERNEL);
        if (!l2cache_pmu)
                return -ENOMEM;

        INIT_LIST_HEAD(&l2cache_pmu->clusters);

        platform_set_drvdata(pdev, l2cache_pmu);
        l2cache_pmu->pmu = (struct pmu) {
                /* suffix is instance id for future use with multiple sockets */
                .name           = "l2cache_0",
                .task_ctx_nr    = perf_invalid_context,
                .pmu_enable     = l2_cache_pmu_enable,
                .pmu_disable    = l2_cache_pmu_disable,
                .event_init     = l2_cache_event_init,
                .add            = l2_cache_event_add,
                .del            = l2_cache_event_del,
                .start          = l2_cache_event_start,
                .stop           = l2_cache_event_stop,
                .read           = l2_cache_event_read,
                .attr_groups    = l2_cache_pmu_attr_grps,
        };

        l2cache_pmu->num_counters = get_num_counters();
        l2cache_pmu->pdev = pdev;
        l2cache_pmu->pmu_cluster = devm_alloc_percpu(&pdev->dev,
                                                     struct cluster_pmu *);
        if (!l2cache_pmu->pmu_cluster)
                return -ENOMEM;

        l2_cycle_ctr_idx = l2cache_pmu->num_counters - 1;
        l2_counter_present_mask = GENMASK(l2cache_pmu->num_counters - 2, 0) |
                BIT(L2CYCLE_CTR_BIT);

        cpumask_clear(&l2cache_pmu->cpumask);

        /* Read cluster info and initialize each cluster */

        err = device_for_each_child(&pdev->dev, l2cache_pmu,
                                    l2_cache_pmu_probe_cluster);
        if (err)
                return err;

        if (l2cache_pmu->num_pmus == 0) {
                dev_err(&pdev->dev, "No hardware L2 cache PMUs found\n");
                return -ENODEV;
        }

        err = cpuhp_state_add_instance(CPUHP_AP_PERF_ARM_QCOM_L2_ONLINE,
                                       &l2cache_pmu->node);
        if (err) {
                dev_err(&pdev->dev, "Error %d registering hotplug", err);
                return err;
        }

        err = perf_pmu_register(&l2cache_pmu->pmu, l2cache_pmu->pmu.name, -1);
        if (err) {
                dev_err(&pdev->dev, "Error %d registering L2 cache PMU\n", err);
                goto out_unregister;
        }

        dev_info(&pdev->dev, "Registered L2 cache PMU using %d HW PMUs\n",
                 l2cache_pmu->num_pmus);

        return err;

out_unregister:
        cpuhp_state_remove_instance(CPUHP_AP_PERF_ARM_QCOM_L2_ONLINE,
                                    &l2cache_pmu->node);
        return err;
}

static int l2_cache_pmu_remove(struct platform_device *pdev)
{
        struct l2cache_pmu *l2cache_pmu =
                to_l2cache_pmu(platform_get_drvdata(pdev));

        perf_pmu_unregister(&l2cache_pmu->pmu);
        cpuhp_state_remove_instance(CPUHP_AP_PERF_ARM_QCOM_L2_ONLINE,
                                    &l2cache_pmu->node);
        return 0;
}

static struct platform_driver l2_cache_pmu_driver = {
        .driver = {
                .name = "qcom-l2cache-pmu",
                .acpi_match_table = ACPI_PTR(l2_cache_pmu_acpi_match),
        },
        .probe = l2_cache_pmu_probe,
        .remove = l2_cache_pmu_remove,
};

static int __init register_l2_cache_pmu_driver(void)
{
        int err;

        err = cpuhp_setup_state_multi(CPUHP_AP_PERF_ARM_QCOM_L2_ONLINE,
                                      "AP_PERF_ARM_QCOM_L2_ONLINE",
                                      l2cache_pmu_online_cpu,
                                      l2cache_pmu_offline_cpu);
        if (err)
                return err;

        return platform_driver_register(&l2_cache_pmu_driver);
}
device_initcall(register_l2_cache_pmu_driver);