// SPDX-License-Identifier: GPL-2.0-only
/*
 * ARM DynamIQ Shared Unit (DSU) PMU driver
 *
 * Copyright (C) ARM Limited, 2017.
 *
 * Based on ARM CCI-PMU, ARMv8 PMU-v3 drivers.
 */

#define PMUNAME         "arm_dsu"
#define DRVNAME         PMUNAME "_pmu"
#define pr_fmt(fmt)     DRVNAME ": " fmt

#include <linux/bitmap.h>
#include <linux/bitops.h>
#include <linux/bug.h>
#include <linux/cpumask.h>
#include <linux/device.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/perf_event.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <linux/smp.h>
#include <linux/sysfs.h>
#include <linux/types.h>

#include <asm/arm_dsu_pmu.h>
#include <asm/local64.h>

/* PMU event codes */
#define DSU_PMU_EVT_CYCLES              0x11
#define DSU_PMU_EVT_CHAIN               0x1e

#define DSU_PMU_MAX_COMMON_EVENTS       0x40

#define DSU_PMU_MAX_HW_CNTRS            32
#define DSU_PMU_HW_COUNTER_MASK         (DSU_PMU_MAX_HW_CNTRS - 1)

#define CLUSTERPMCR_E                   BIT(0)
#define CLUSTERPMCR_P                   BIT(1)
#define CLUSTERPMCR_C                   BIT(2)
#define CLUSTERPMCR_N_SHIFT             11
#define CLUSTERPMCR_N_MASK              0x1f
#define CLUSTERPMCR_IDCODE_SHIFT        16
#define CLUSTERPMCR_IDCODE_MASK         0xff
#define CLUSTERPMCR_IMP_SHIFT           24
#define CLUSTERPMCR_IMP_MASK            0xff
#define CLUSTERPMCR_RES_MASK            0x7e8
#define CLUSTERPMCR_RES_VAL             0x40

#define DSU_ACTIVE_CPU_MASK             0x0
#define DSU_ASSOCIATED_CPU_MASK         0x1

/*
 * We use the index of the counters as they appear in the counter
 * bit maps in the PMU registers (e.g CLUSTERPMSELR).
 * i.e,
 *      counter 0       - Bit 0
 *      counter 1       - Bit 1
 *      ...
 *      Cycle counter   - Bit 31
 */
#define DSU_PMU_IDX_CYCLE_COUNTER       31

/* All event counters are 32bit, with a 64bit Cycle counter */
#define DSU_PMU_COUNTER_WIDTH(idx)      \
        (((idx) == DSU_PMU_IDX_CYCLE_COUNTER) ? 64 : 32)

#define DSU_PMU_COUNTER_MASK(idx)       \
        GENMASK_ULL((DSU_PMU_COUNTER_WIDTH((idx)) - 1), 0)

#define DSU_EXT_ATTR(_name, _func, _config)             \
        (&((struct dev_ext_attribute[]) {                               \
                {                                                       \
                        .attr = __ATTR(_name, 0444, _func, NULL),       \
                        .var = (void *)_config                          \
                }                                                       \
        })[0].attr.attr)

#define DSU_EVENT_ATTR(_name, _config)          \
        DSU_EXT_ATTR(_name, dsu_pmu_sysfs_event_show, (unsigned long)_config)

#define DSU_FORMAT_ATTR(_name, _config)         \
        DSU_EXT_ATTR(_name, dsu_pmu_sysfs_format_show, (char *)_config)

#define DSU_CPUMASK_ATTR(_name, _config)        \
        DSU_EXT_ATTR(_name, dsu_pmu_cpumask_show, (unsigned long)_config)

struct dsu_hw_events {
        DECLARE_BITMAP(used_mask, DSU_PMU_MAX_HW_CNTRS);
        struct perf_event       *events[DSU_PMU_MAX_HW_CNTRS];
};

/*
 * struct dsu_pmu       - DSU PMU descriptor
 *
 * @pmu_lock            : Protects accesses to DSU PMU register from normal vs
 *                        interrupt handler contexts.
 * @hw_events           : Holds the event counter state.
 * @associated_cpus     : CPUs attached to the DSU.
 * @active_cpu          : CPU to which the PMU is bound for accesses.
 * @cpuhp_node          : Node for CPU hotplug notifier link.
 * @num_counters        : Number of event counters implemented by the PMU,
 *                        excluding the cycle counter.
 * @irq                 : Interrupt line for counter overflow.
 * @cpmceid_bitmap      : Bitmap for the availability of architected common
 *                        events (event_code < 0x40).
 */
struct dsu_pmu {
        struct pmu                      pmu;
        struct device                   *dev;
        raw_spinlock_t                  pmu_lock;
        struct dsu_hw_events            hw_events;
        cpumask_t                       associated_cpus;
        cpumask_t                       active_cpu;
        struct hlist_node               cpuhp_node;
        s8                              num_counters;
        int                             irq;
        DECLARE_BITMAP(cpmceid_bitmap, DSU_PMU_MAX_COMMON_EVENTS);
};

static unsigned long dsu_pmu_cpuhp_state;

static inline struct dsu_pmu *to_dsu_pmu(struct pmu *pmu)
{
        return container_of(pmu, struct dsu_pmu, pmu);
}

static ssize_t dsu_pmu_sysfs_event_show(struct device *dev,
                                        struct device_attribute *attr,
                                        char *buf)
{
        struct dev_ext_attribute *eattr = container_of(attr,
                                        struct dev_ext_attribute, attr);
        return snprintf(buf, PAGE_SIZE, "event=0x%lx\n",
                                         (unsigned long)eattr->var);
}

static ssize_t dsu_pmu_sysfs_format_show(struct device *dev,
                                         struct device_attribute *attr,
                                         char *buf)
{
        struct dev_ext_attribute *eattr = container_of(attr,
                                        struct dev_ext_attribute, attr);
        return snprintf(buf, PAGE_SIZE, "%s\n", (char *)eattr->var);
}

static ssize_t dsu_pmu_cpumask_show(struct device *dev,
                                    struct device_attribute *attr,
                                    char *buf)
{
        struct pmu *pmu = dev_get_drvdata(dev);
        struct dsu_pmu *dsu_pmu = to_dsu_pmu(pmu);
        struct dev_ext_attribute *eattr = container_of(attr,
                                        struct dev_ext_attribute, attr);
        unsigned long mask_id = (unsigned long)eattr->var;
        const cpumask_t *cpumask;

        switch (mask_id) {
        case DSU_ACTIVE_CPU_MASK:
                cpumask = &dsu_pmu->active_cpu;
                break;
        case DSU_ASSOCIATED_CPU_MASK:
                cpumask = &dsu_pmu->associated_cpus;
                break;
        default:
                return 0;
        }
        return cpumap_print_to_pagebuf(true, buf, cpumask);
}

static struct attribute *dsu_pmu_format_attrs[] = {
        DSU_FORMAT_ATTR(event, "config:0-31"),
        NULL,
};

static const struct attribute_group dsu_pmu_format_attr_group = {
        .name = "format",
        .attrs = dsu_pmu_format_attrs,
};

static struct attribute *dsu_pmu_event_attrs[] = {
        DSU_EVENT_ATTR(cycles, 0x11),
        DSU_EVENT_ATTR(bus_access, 0x19),
        DSU_EVENT_ATTR(memory_error, 0x1a),
        DSU_EVENT_ATTR(bus_cycles, 0x1d),
        DSU_EVENT_ATTR(l3d_cache_allocate, 0x29),
        DSU_EVENT_ATTR(l3d_cache_refill, 0x2a),
        DSU_EVENT_ATTR(l3d_cache, 0x2b),
        DSU_EVENT_ATTR(l3d_cache_wb, 0x2c),
        NULL,
};

static umode_t
dsu_pmu_event_attr_is_visible(struct kobject *kobj, struct attribute *attr,
                                int unused)
{
        struct pmu *pmu = dev_get_drvdata(kobj_to_dev(kobj));
        struct dsu_pmu *dsu_pmu = to_dsu_pmu(pmu);
        struct dev_ext_attribute *eattr = container_of(attr,
                                        struct dev_ext_attribute, attr.attr);
        unsigned long evt = (unsigned long)eattr->var;

        return test_bit(evt, dsu_pmu->cpmceid_bitmap) ? attr->mode : 0;
}

static const struct attribute_group dsu_pmu_events_attr_group = {
        .name = "events",
        .attrs = dsu_pmu_event_attrs,
        .is_visible = dsu_pmu_event_attr_is_visible,
};

static struct attribute *dsu_pmu_cpumask_attrs[] = {
        DSU_CPUMASK_ATTR(cpumask, DSU_ACTIVE_CPU_MASK),
        DSU_CPUMASK_ATTR(associated_cpus, DSU_ASSOCIATED_CPU_MASK),
        NULL,
};

static const struct attribute_group dsu_pmu_cpumask_attr_group = {
        .attrs = dsu_pmu_cpumask_attrs,
};

static const struct attribute_group *dsu_pmu_attr_groups[] = {
        &dsu_pmu_cpumask_attr_group,
        &dsu_pmu_events_attr_group,
        &dsu_pmu_format_attr_group,
        NULL,
};

static int dsu_pmu_get_online_cpu_any_but(struct dsu_pmu *dsu_pmu, int cpu)
{
        struct cpumask online_supported;

        cpumask_and(&online_supported,
                         &dsu_pmu->associated_cpus, cpu_online_mask);
        return cpumask_any_but(&online_supported, cpu);
}

static inline bool dsu_pmu_counter_valid(struct dsu_pmu *dsu_pmu, u32 idx)
{
        return (idx < dsu_pmu->num_counters) ||
               (idx == DSU_PMU_IDX_CYCLE_COUNTER);
}

static inline u64 dsu_pmu_read_counter(struct perf_event *event)
{
        u64 val;
        unsigned long flags;
        struct dsu_pmu *dsu_pmu = to_dsu_pmu(event->pmu);
        int idx = event->hw.idx;

        if (WARN_ON(!cpumask_test_cpu(smp_processor_id(),
                                 &dsu_pmu->associated_cpus)))
                return 0;

        if (!dsu_pmu_counter_valid(dsu_pmu, idx)) {
                dev_err(event->pmu->dev,
                        "Trying reading invalid counter %d\n", idx);
                return 0;
        }

        raw_spin_lock_irqsave(&dsu_pmu->pmu_lock, flags);
        if (idx == DSU_PMU_IDX_CYCLE_COUNTER)
                val = __dsu_pmu_read_pmccntr();
        else
                val = __dsu_pmu_read_counter(idx);
        raw_spin_unlock_irqrestore(&dsu_pmu->pmu_lock, flags);

        return val;
}

static void dsu_pmu_write_counter(struct perf_event *event, u64 val)
{
        unsigned long flags;
        struct dsu_pmu *dsu_pmu = to_dsu_pmu(event->pmu);
        int idx = event->hw.idx;

        if (WARN_ON(!cpumask_test_cpu(smp_processor_id(),
                         &dsu_pmu->associated_cpus)))
                return;

        if (!dsu_pmu_counter_valid(dsu_pmu, idx)) {
                dev_err(event->pmu->dev,
                        "writing to invalid counter %d\n", idx);
                return;
        }

        raw_spin_lock_irqsave(&dsu_pmu->pmu_lock, flags);
        if (idx == DSU_PMU_IDX_CYCLE_COUNTER)
                __dsu_pmu_write_pmccntr(val);
        else
                __dsu_pmu_write_counter(idx, val);
        raw_spin_unlock_irqrestore(&dsu_pmu->pmu_lock, flags);
}

static int dsu_pmu_get_event_idx(struct dsu_hw_events *hw_events,
                                 struct perf_event *event)
{
        int idx;
        unsigned long evtype = event->attr.config;
        struct dsu_pmu *dsu_pmu = to_dsu_pmu(event->pmu);
        unsigned long *used_mask = hw_events->used_mask;

        if (evtype == DSU_PMU_EVT_CYCLES) {
                if (test_and_set_bit(DSU_PMU_IDX_CYCLE_COUNTER, used_mask))
                        return -EAGAIN;
                return DSU_PMU_IDX_CYCLE_COUNTER;
        }

        idx = find_first_zero_bit(used_mask, dsu_pmu->num_counters);
        if (idx >= dsu_pmu->num_counters)
                return -EAGAIN;
        set_bit(idx, hw_events->used_mask);
        return idx;
}

static void dsu_pmu_enable_counter(struct dsu_pmu *dsu_pmu, int idx)
{
        __dsu_pmu_counter_interrupt_enable(idx);
        __dsu_pmu_enable_counter(idx);
}

static void dsu_pmu_disable_counter(struct dsu_pmu *dsu_pmu, int idx)
{
        __dsu_pmu_disable_counter(idx);
        __dsu_pmu_counter_interrupt_disable(idx);
}

static inline void dsu_pmu_set_event(struct dsu_pmu *dsu_pmu,
                                        struct perf_event *event)
{
        int idx = event->hw.idx;
        unsigned long flags;

        if (!dsu_pmu_counter_valid(dsu_pmu, idx)) {
                dev_err(event->pmu->dev,
                        "Trying to set invalid counter %d\n", idx);
                return;
        }

        raw_spin_lock_irqsave(&dsu_pmu->pmu_lock, flags);
        __dsu_pmu_set_event(idx, event->hw.config_base);
        raw_spin_unlock_irqrestore(&dsu_pmu->pmu_lock, flags);
}

static void dsu_pmu_event_update(struct perf_event *event)
{
        struct hw_perf_event *hwc = &event->hw;
        u64 delta, prev_count, new_count;

        do {
                /* We may also be called from the irq handler */
                prev_count = local64_read(&hwc->prev_count);
                new_count = dsu_pmu_read_counter(event);
        } while (local64_cmpxchg(&hwc->prev_count, prev_count, new_count) !=
                        prev_count);
        delta = (new_count - prev_count) & DSU_PMU_COUNTER_MASK(hwc->idx);
        local64_add(delta, &event->count);
}

static void dsu_pmu_read(struct perf_event *event)
{
        dsu_pmu_event_update(event);
}

static inline u32 dsu_pmu_get_reset_overflow(void)
{
        return __dsu_pmu_get_reset_overflow();
}

/**
 * dsu_pmu_set_event_period: Set the period for the counter.
 *
 * All DSU PMU event counters, except the cycle counter are 32bit
 * counters. To handle cases of extreme interrupt latency, we program
 * the counter with half of the max count for the counters.
 */
static void dsu_pmu_set_event_period(struct perf_event *event)
{
        int idx = event->hw.idx;
        u64 val = DSU_PMU_COUNTER_MASK(idx) >> 1;

        local64_set(&event->hw.prev_count, val);
        dsu_pmu_write_counter(event, val);
}

static irqreturn_t dsu_pmu_handle_irq(int irq_num, void *dev)
{
        int i;
        bool handled = false;
        struct dsu_pmu *dsu_pmu = dev;
        struct dsu_hw_events *hw_events = &dsu_pmu->hw_events;
        unsigned long overflow;

        overflow = dsu_pmu_get_reset_overflow();
        if (!overflow)
                return IRQ_NONE;

        for_each_set_bit(i, &overflow, DSU_PMU_MAX_HW_CNTRS) {
                struct perf_event *event = hw_events->events[i];

                if (!event)
                        continue;
                dsu_pmu_event_update(event);
                dsu_pmu_set_event_period(event);
                handled = true;
        }

        return IRQ_RETVAL(handled);
}

static void dsu_pmu_start(struct perf_event *event, int pmu_flags)
{
        struct dsu_pmu *dsu_pmu = to_dsu_pmu(event->pmu);

        /* We always reprogram the counter */
        if (pmu_flags & PERF_EF_RELOAD)
                WARN_ON(!(event->hw.state & PERF_HES_UPTODATE));
        dsu_pmu_set_event_period(event);
        if (event->hw.idx != DSU_PMU_IDX_CYCLE_COUNTER)
                dsu_pmu_set_event(dsu_pmu, event);
        event->hw.state = 0;
        dsu_pmu_enable_counter(dsu_pmu, event->hw.idx);
}

static void dsu_pmu_stop(struct perf_event *event, int pmu_flags)
{
        struct dsu_pmu *dsu_pmu = to_dsu_pmu(event->pmu);

        if (event->hw.state & PERF_HES_STOPPED)
                return;
        dsu_pmu_disable_counter(dsu_pmu, event->hw.idx);
        dsu_pmu_event_update(event);
        event->hw.state |= PERF_HES_STOPPED | PERF_HES_UPTODATE;
}

static int dsu_pmu_add(struct perf_event *event, int flags)
{
        struct dsu_pmu *dsu_pmu = to_dsu_pmu(event->pmu);
        struct dsu_hw_events *hw_events = &dsu_pmu->hw_events;
        struct hw_perf_event *hwc = &event->hw;
        int idx;

        if (WARN_ON_ONCE(!cpumask_test_cpu(smp_processor_id(),
                                           &dsu_pmu->associated_cpus)))
                return -ENOENT;

        idx = dsu_pmu_get_event_idx(hw_events, event);
        if (idx < 0)
                return idx;

        hwc->idx = idx;
        hw_events->events[idx] = event;
        hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;

        if (flags & PERF_EF_START)
                dsu_pmu_start(event, PERF_EF_RELOAD);

        perf_event_update_userpage(event);
        return 0;
}

static void dsu_pmu_del(struct perf_event *event, int flags)
{
        struct dsu_pmu *dsu_pmu = to_dsu_pmu(event->pmu);
        struct dsu_hw_events *hw_events = &dsu_pmu->hw_events;
        struct hw_perf_event *hwc = &event->hw;
        int idx = hwc->idx;

        dsu_pmu_stop(event, PERF_EF_UPDATE);
        hw_events->events[idx] = NULL;
        clear_bit(idx, hw_events->used_mask);
        perf_event_update_userpage(event);
}

static void dsu_pmu_enable(struct pmu *pmu)
{
        u32 pmcr;
        unsigned long flags;
        struct dsu_pmu *dsu_pmu = to_dsu_pmu(pmu);

        /* If no counters are added, skip enabling the PMU */
        if (bitmap_empty(dsu_pmu->hw_events.used_mask, DSU_PMU_MAX_HW_CNTRS))
                return;

        raw_spin_lock_irqsave(&dsu_pmu->pmu_lock, flags);
        pmcr = __dsu_pmu_read_pmcr();
        pmcr |= CLUSTERPMCR_E;
        __dsu_pmu_write_pmcr(pmcr);
        raw_spin_unlock_irqrestore(&dsu_pmu->pmu_lock, flags);
}

static void dsu_pmu_disable(struct pmu *pmu)
{
        u32 pmcr;
        unsigned long flags;
        struct dsu_pmu *dsu_pmu = to_dsu_pmu(pmu);

        raw_spin_lock_irqsave(&dsu_pmu->pmu_lock, flags);
        pmcr = __dsu_pmu_read_pmcr();
        pmcr &= ~CLUSTERPMCR_E;
        __dsu_pmu_write_pmcr(pmcr);
        raw_spin_unlock_irqrestore(&dsu_pmu->pmu_lock, flags);
}

static bool dsu_pmu_validate_event(struct pmu *pmu,
                                  struct dsu_hw_events *hw_events,
                                  struct perf_event *event)
{
        if (is_software_event(event))
                return true;
        /* Reject groups spanning multiple HW PMUs. */
        if (event->pmu != pmu)
                return false;
        return dsu_pmu_get_event_idx(hw_events, event) >= 0;
}

/*
 * Make sure the group of events can be scheduled at once
 * on the PMU.
 */
static bool dsu_pmu_validate_group(struct perf_event *event)
{
        struct perf_event *sibling, *leader = event->group_leader;
        struct dsu_hw_events fake_hw;

        if (event->group_leader == event)
                return true;

        memset(fake_hw.used_mask, 0, sizeof(fake_hw.used_mask));
        if (!dsu_pmu_validate_event(event->pmu, &fake_hw, leader))
                return false;
        for_each_sibling_event(sibling, leader) {
                if (!dsu_pmu_validate_event(event->pmu, &fake_hw, sibling))
                        return false;
        }
        return dsu_pmu_validate_event(event->pmu, &fake_hw, event);
}

static int dsu_pmu_event_init(struct perf_event *event)
{
        struct dsu_pmu *dsu_pmu = to_dsu_pmu(event->pmu);

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

        /* We don't support sampling */
        if (is_sampling_event(event)) {
                dev_dbg(dsu_pmu->pmu.dev, "Can't support sampling events\n");
                return -EOPNOTSUPP;
        }

        /* We cannot support task bound events */
        if (event->cpu < 0 || event->attach_state & PERF_ATTACH_TASK) {
                dev_dbg(dsu_pmu->pmu.dev, "Can't support per-task counters\n");
                return -EINVAL;
        }

        if (has_branch_stack(event)) {
                dev_dbg(dsu_pmu->pmu.dev, "Can't support filtering\n");
                return -EINVAL;
        }

        if (!cpumask_test_cpu(event->cpu, &dsu_pmu->associated_cpus)) {
                dev_dbg(dsu_pmu->pmu.dev,
                         "Requested cpu is not associated with the DSU\n");
                return -EINVAL;
        }
        /*
         * Choose the current active CPU to read the events. We don't want
         * to migrate the event contexts, irq handling etc to the requested
         * CPU. As long as the requested CPU is within the same DSU, we
         * are fine.
         */
        event->cpu = cpumask_first(&dsu_pmu->active_cpu);
        if (event->cpu >= nr_cpu_ids)
                return -EINVAL;
        if (!dsu_pmu_validate_group(event))
                return -EINVAL;

        event->hw.config_base = event->attr.config;
        return 0;
}

static struct dsu_pmu *dsu_pmu_alloc(struct platform_device *pdev)
{
        struct dsu_pmu *dsu_pmu;

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

        raw_spin_lock_init(&dsu_pmu->pmu_lock);
        /*
         * Initialise the number of counters to -1, until we probe
         * the real number on a connected CPU.
         */
        dsu_pmu->num_counters = -1;
        return dsu_pmu;
}

/**
 * dsu_pmu_dt_get_cpus: Get the list of CPUs in the cluster.
 */
static int dsu_pmu_dt_get_cpus(struct device_node *dev, cpumask_t *mask)
{
        int i = 0, n, cpu;
        struct device_node *cpu_node;

        n = of_count_phandle_with_args(dev, "cpus", NULL);
        if (n <= 0)
                return -ENODEV;
        for (; i < n; i++) {
                cpu_node = of_parse_phandle(dev, "cpus", i);
                if (!cpu_node)
                        break;
                cpu = of_cpu_node_to_id(cpu_node);
                of_node_put(cpu_node);
                /*
                 * We have to ignore the failures here and continue scanning
                 * the list to handle cases where the nr_cpus could be capped
                 * in the running kernel.
                 */
                if (cpu < 0)
                        continue;
                cpumask_set_cpu(cpu, mask);
        }
        return 0;
}

/*
 * dsu_pmu_probe_pmu: Probe the PMU details on a CPU in the cluster.
 */
static void dsu_pmu_probe_pmu(struct dsu_pmu *dsu_pmu)
{
        u64 num_counters;
        u32 cpmceid[2];

        num_counters = (__dsu_pmu_read_pmcr() >> CLUSTERPMCR_N_SHIFT) &
                                                CLUSTERPMCR_N_MASK;
        /* We can only support up to 31 independent counters */
        if (WARN_ON(num_counters > 31))
                num_counters = 31;
        dsu_pmu->num_counters = num_counters;
        if (!dsu_pmu->num_counters)
                return;
        cpmceid[0] = __dsu_pmu_read_pmceid(0);
        cpmceid[1] = __dsu_pmu_read_pmceid(1);
        bitmap_from_arr32(dsu_pmu->cpmceid_bitmap, cpmceid,
                          DSU_PMU_MAX_COMMON_EVENTS);
}

static void dsu_pmu_set_active_cpu(int cpu, struct dsu_pmu *dsu_pmu)
{
        cpumask_set_cpu(cpu, &dsu_pmu->active_cpu);
        if (irq_set_affinity_hint(dsu_pmu->irq, &dsu_pmu->active_cpu))
                pr_warn("Failed to set irq affinity to %d\n", cpu);
}

/*
 * dsu_pmu_init_pmu: Initialise the DSU PMU configurations if
 * we haven't done it already.
 */
static void dsu_pmu_init_pmu(struct dsu_pmu *dsu_pmu)
{
        if (dsu_pmu->num_counters == -1)
                dsu_pmu_probe_pmu(dsu_pmu);
        /* Reset the interrupt overflow mask */
        dsu_pmu_get_reset_overflow();
}

static int dsu_pmu_device_probe(struct platform_device *pdev)
{
        int irq, rc;
        struct dsu_pmu *dsu_pmu;
        char *name;
        static atomic_t pmu_idx = ATOMIC_INIT(-1);

        dsu_pmu = dsu_pmu_alloc(pdev);
        if (IS_ERR(dsu_pmu))
                return PTR_ERR(dsu_pmu);

        rc = dsu_pmu_dt_get_cpus(pdev->dev.of_node, &dsu_pmu->associated_cpus);
        if (rc) {
                dev_warn(&pdev->dev, "Failed to parse the CPUs\n");
                return rc;
        }

        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return -EINVAL;

        name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%s_%d",
                                PMUNAME, atomic_inc_return(&pmu_idx));
        if (!name)
                return -ENOMEM;
        rc = devm_request_irq(&pdev->dev, irq, dsu_pmu_handle_irq,
                              IRQF_NOBALANCING, name, dsu_pmu);
        if (rc) {
                dev_warn(&pdev->dev, "Failed to request IRQ %d\n", irq);
                return rc;
        }

        dsu_pmu->irq = irq;
        platform_set_drvdata(pdev, dsu_pmu);
        rc = cpuhp_state_add_instance(dsu_pmu_cpuhp_state,
                                                &dsu_pmu->cpuhp_node);
        if (rc)
                return rc;

        dsu_pmu->pmu = (struct pmu) {
                .task_ctx_nr    = perf_invalid_context,
                .module         = THIS_MODULE,
                .pmu_enable     = dsu_pmu_enable,
                .pmu_disable    = dsu_pmu_disable,
                .event_init     = dsu_pmu_event_init,
                .add            = dsu_pmu_add,
                .del            = dsu_pmu_del,
                .start          = dsu_pmu_start,
                .stop           = dsu_pmu_stop,
                .read           = dsu_pmu_read,

                .attr_groups    = dsu_pmu_attr_groups,
                .capabilities   = PERF_PMU_CAP_NO_EXCLUDE,
        };

        rc = perf_pmu_register(&dsu_pmu->pmu, name, -1);
        if (rc) {
                cpuhp_state_remove_instance(dsu_pmu_cpuhp_state,
                                                 &dsu_pmu->cpuhp_node);
                irq_set_affinity_hint(dsu_pmu->irq, NULL);
        }

        return rc;
}

static int dsu_pmu_device_remove(struct platform_device *pdev)
{
        struct dsu_pmu *dsu_pmu = platform_get_drvdata(pdev);

        perf_pmu_unregister(&dsu_pmu->pmu);
        cpuhp_state_remove_instance(dsu_pmu_cpuhp_state, &dsu_pmu->cpuhp_node);
        irq_set_affinity_hint(dsu_pmu->irq, NULL);

        return 0;
}

static const struct of_device_id dsu_pmu_of_match[] = {
        { .compatible = "arm,dsu-pmu", },
        {},
};

static struct platform_driver dsu_pmu_driver = {
        .driver = {
                .name   = DRVNAME,
                .of_match_table = of_match_ptr(dsu_pmu_of_match),
                .suppress_bind_attrs = true,
        },
        .probe = dsu_pmu_device_probe,
        .remove = dsu_pmu_device_remove,
};

static int dsu_pmu_cpu_online(unsigned int cpu, struct hlist_node *node)
{
        struct dsu_pmu *dsu_pmu = hlist_entry_safe(node, struct dsu_pmu,
                                                   cpuhp_node);

        if (!cpumask_test_cpu(cpu, &dsu_pmu->associated_cpus))
                return 0;

        /* If the PMU is already managed, there is nothing to do */
        if (!cpumask_empty(&dsu_pmu->active_cpu))
                return 0;

        dsu_pmu_init_pmu(dsu_pmu);
        dsu_pmu_set_active_cpu(cpu, dsu_pmu);

        return 0;
}

static int dsu_pmu_cpu_teardown(unsigned int cpu, struct hlist_node *node)
{
        int dst;
        struct dsu_pmu *dsu_pmu = hlist_entry_safe(node, struct dsu_pmu,
                                                   cpuhp_node);

        if (!cpumask_test_and_clear_cpu(cpu, &dsu_pmu->active_cpu))
                return 0;

        dst = dsu_pmu_get_online_cpu_any_but(dsu_pmu, cpu);
        /* If there are no active CPUs in the DSU, leave IRQ disabled */
        if (dst >= nr_cpu_ids) {
                irq_set_affinity_hint(dsu_pmu->irq, NULL);
                return 0;
        }

        perf_pmu_migrate_context(&dsu_pmu->pmu, cpu, dst);
        dsu_pmu_set_active_cpu(dst, dsu_pmu);

        return 0;
}

static int __init dsu_pmu_init(void)
{
        int ret;

        ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN,
                                        DRVNAME,
                                        dsu_pmu_cpu_online,
                                        dsu_pmu_cpu_teardown);
        if (ret < 0)
                return ret;
        dsu_pmu_cpuhp_state = ret;
        return platform_driver_register(&dsu_pmu_driver);
}

static void __exit dsu_pmu_exit(void)
{
        platform_driver_unregister(&dsu_pmu_driver);
        cpuhp_remove_multi_state(dsu_pmu_cpuhp_state);
}

module_init(dsu_pmu_init);
module_exit(dsu_pmu_exit);

MODULE_DEVICE_TABLE(of, dsu_pmu_of_match);
MODULE_DESCRIPTION("Perf driver for ARM DynamIQ Shared Unit");
MODULE_AUTHOR("Suzuki K Poulose <suzuki.poulose@arm.com>");
MODULE_LICENSE("GPL v2");