/*
 * L220/L310 cache controller support
 *
 * Copyright (C) 2016 ARM Limited
 *
 * 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.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
#include <linux/errno.h>
#include <linux/hrtimer.h>
#include <linux/io.h>
#include <linux/list.h>
#include <linux/perf_event.h>
#include <linux/printk.h>
#include <linux/slab.h>
#include <linux/types.h>

#include <asm/hardware/cache-l2x0.h>

#define PMU_NR_COUNTERS 2

static void __iomem *l2x0_base;
static struct pmu *l2x0_pmu;
static cpumask_t pmu_cpu;

static const char *l2x0_name;

static ktime_t l2x0_pmu_poll_period;
static struct hrtimer l2x0_pmu_hrtimer;

/*
 * The L220/PL310 PMU has two equivalent counters, Counter1 and Counter0.
 * Registers controlling these are laid out in pairs, in descending order, i.e.
 * the register for Counter1 comes first, followed by the register for
 * Counter0.
 * We ensure that idx 0 -> Counter0, and idx1 -> Counter1.
 */
static struct perf_event *events[PMU_NR_COUNTERS];

/* Find an unused counter */
static int l2x0_pmu_find_idx(void)
{
        int i;

        for (i = 0; i < PMU_NR_COUNTERS; i++) {
                if (!events[i])
                        return i;
        }

        return -1;
}

/* How many counters are allocated? */
static int l2x0_pmu_num_active_counters(void)
{
        int i, cnt = 0;

        for (i = 0; i < PMU_NR_COUNTERS; i++) {
                if (events[i])
                        cnt++;
        }

        return cnt;
}

static void l2x0_pmu_counter_config_write(int idx, u32 val)
{
        writel_relaxed(val, l2x0_base + L2X0_EVENT_CNT0_CFG - 4 * idx);
}

static u32 l2x0_pmu_counter_read(int idx)
{
        return readl_relaxed(l2x0_base + L2X0_EVENT_CNT0_VAL - 4 * idx);
}

static void l2x0_pmu_counter_write(int idx, u32 val)
{
        writel_relaxed(val, l2x0_base + L2X0_EVENT_CNT0_VAL - 4 * idx);
}

static void __l2x0_pmu_enable(void)
{
        u32 val = readl_relaxed(l2x0_base + L2X0_EVENT_CNT_CTRL);
        val |= L2X0_EVENT_CNT_CTRL_ENABLE;
        writel_relaxed(val, l2x0_base + L2X0_EVENT_CNT_CTRL);
}

static void __l2x0_pmu_disable(void)
{
        u32 val = readl_relaxed(l2x0_base + L2X0_EVENT_CNT_CTRL);
        val &= ~L2X0_EVENT_CNT_CTRL_ENABLE;
        writel_relaxed(val, l2x0_base + L2X0_EVENT_CNT_CTRL);
}

static void l2x0_pmu_enable(struct pmu *pmu)
{
        if (l2x0_pmu_num_active_counters() == 0)
                return;

        __l2x0_pmu_enable();
}

static void l2x0_pmu_disable(struct pmu *pmu)
{
        if (l2x0_pmu_num_active_counters() == 0)
                return;

        __l2x0_pmu_disable();
}

static void warn_if_saturated(u32 count)
{
        if (count != 0xffffffff)
                return;

        pr_warn_ratelimited("L2X0 counter saturated. Poll period too long\n");
}

static void l2x0_pmu_event_read(struct perf_event *event)
{
        struct hw_perf_event *hw = &event->hw;
        u64 prev_count, new_count, mask;

        do {
                 prev_count = local64_read(&hw->prev_count);
                 new_count = l2x0_pmu_counter_read(hw->idx);
        } while (local64_xchg(&hw->prev_count, new_count) != prev_count);

        mask = GENMASK_ULL(31, 0);
        local64_add((new_count - prev_count) & mask, &event->count);

        warn_if_saturated(new_count);
}

static void l2x0_pmu_event_configure(struct perf_event *event)
{
        struct hw_perf_event *hw = &event->hw;

        /*
         * The L2X0 counters saturate at 0xffffffff rather than wrapping, so we
         * will *always* lose some number of events when a counter saturates,
         * and have no way of detecting how many were lost.
         *
         * To minimize the impact of this, we try to maximize the period by
         * always starting counters at zero. To ensure that group ratios are
         * representative, we poll periodically to avoid counters saturating.
         * See l2x0_pmu_poll().
         */
        local64_set(&hw->prev_count, 0);
        l2x0_pmu_counter_write(hw->idx, 0);
}

static enum hrtimer_restart l2x0_pmu_poll(struct hrtimer *hrtimer)
{
        unsigned long flags;
        int i;

        local_irq_save(flags);
        __l2x0_pmu_disable();

        for (i = 0; i < PMU_NR_COUNTERS; i++) {
                struct perf_event *event = events[i];

                if (!event)
                        continue;

                l2x0_pmu_event_read(event);
                l2x0_pmu_event_configure(event);
        }

        __l2x0_pmu_enable();
        local_irq_restore(flags);

        hrtimer_forward_now(hrtimer, l2x0_pmu_poll_period);
        return HRTIMER_RESTART;
}


static void __l2x0_pmu_event_enable(int idx, u32 event)
{
        u32 val;

        val = event << L2X0_EVENT_CNT_CFG_SRC_SHIFT;
        val |= L2X0_EVENT_CNT_CFG_INT_DISABLED;
        l2x0_pmu_counter_config_write(idx, val);
}

static void l2x0_pmu_event_start(struct perf_event *event, int flags)
{
        struct hw_perf_event *hw = &event->hw;

        if (WARN_ON_ONCE(!(event->hw.state & PERF_HES_STOPPED)))
                return;

        if (flags & PERF_EF_RELOAD) {
                WARN_ON_ONCE(!(hw->state & PERF_HES_UPTODATE));
                l2x0_pmu_event_configure(event);
        }

        hw->state = 0;

        __l2x0_pmu_event_enable(hw->idx, hw->config_base);
}

static void __l2x0_pmu_event_disable(int idx)
{
        u32 val;

        val = L2X0_EVENT_CNT_CFG_SRC_DISABLED << L2X0_EVENT_CNT_CFG_SRC_SHIFT;
        val |= L2X0_EVENT_CNT_CFG_INT_DISABLED;
        l2x0_pmu_counter_config_write(idx, val);
}

static void l2x0_pmu_event_stop(struct perf_event *event, int flags)
{
        struct hw_perf_event *hw = &event->hw;

        if (WARN_ON_ONCE(event->hw.state & PERF_HES_STOPPED))
                return;

        __l2x0_pmu_event_disable(hw->idx);

        hw->state |= PERF_HES_STOPPED;

        if (flags & PERF_EF_UPDATE) {
                l2x0_pmu_event_read(event);
                hw->state |= PERF_HES_UPTODATE;
        }
}

static int l2x0_pmu_event_add(struct perf_event *event, int flags)
{
        struct hw_perf_event *hw = &event->hw;
        int idx = l2x0_pmu_find_idx();

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

        /*
         * Pin the timer, so that the overflows are handled by the chosen
         * event->cpu (this is the same one as presented in "cpumask"
         * attribute).
         */
        if (l2x0_pmu_num_active_counters() == 0)
                hrtimer_start(&l2x0_pmu_hrtimer, l2x0_pmu_poll_period,
                              HRTIMER_MODE_REL_PINNED);

        events[idx] = event;
        hw->idx = idx;

        l2x0_pmu_event_configure(event);

        hw->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;

        if (flags & PERF_EF_START)
                l2x0_pmu_event_start(event, 0);

        return 0;
}

static void l2x0_pmu_event_del(struct perf_event *event, int flags)
{
        struct hw_perf_event *hw = &event->hw;

        l2x0_pmu_event_stop(event, PERF_EF_UPDATE);

        events[hw->idx] = NULL;
        hw->idx = -1;

        if (l2x0_pmu_num_active_counters() == 0)
                hrtimer_cancel(&l2x0_pmu_hrtimer);
}

static bool l2x0_pmu_group_is_valid(struct perf_event *event)
{
        struct pmu *pmu = event->pmu;
        struct perf_event *leader = event->group_leader;
        struct perf_event *sibling;
        int num_hw = 0;

        if (leader->pmu == pmu)
                num_hw++;
        else if (!is_software_event(leader))
                return false;

        list_for_each_entry(sibling, &leader->sibling_list, group_entry) {
                if (sibling->pmu == pmu)
                        num_hw++;
                else if (!is_software_event(sibling))
                        return false;
        }

        return num_hw <= PMU_NR_COUNTERS;
}

static int l2x0_pmu_event_init(struct perf_event *event)
{
        struct hw_perf_event *hw = &event->hw;

        if (event->attr.type != l2x0_pmu->type)
                return -ENOENT;

        if (is_sampling_event(event) ||
            event->attach_state & PERF_ATTACH_TASK)
                return -EINVAL;

        if (event->attr.exclude_user   ||
            event->attr.exclude_kernel ||
            event->attr.exclude_hv     ||
            event->attr.exclude_idle   ||
            event->attr.exclude_host   ||
            event->attr.exclude_guest)
                return -EINVAL;

        if (event->cpu < 0)
                return -EINVAL;

        if (event->attr.config & ~L2X0_EVENT_CNT_CFG_SRC_MASK)
                return -EINVAL;

        hw->config_base = event->attr.config;

        if (!l2x0_pmu_group_is_valid(event))
                return -EINVAL;

        event->cpu = cpumask_first(&pmu_cpu);

        return 0;
}

struct l2x0_event_attribute {
        struct device_attribute attr;
        unsigned int config;
        bool pl310_only;
};

#define L2X0_EVENT_ATTR(_name, _config, _pl310_only)                            \
        (&((struct l2x0_event_attribute[]) {{                                   \
                .attr = __ATTR(_name, S_IRUGO, l2x0_pmu_event_show, NULL),      \
                .config = _config,                                              \
                .pl310_only = _pl310_only,                                      \
        }})[0].attr.attr)

#define L220_PLUS_EVENT_ATTR(_name, _config)                                    \
        L2X0_EVENT_ATTR(_name, _config, false)

#define PL310_EVENT_ATTR(_name, _config)                                        \
        L2X0_EVENT_ATTR(_name, _config, true)

static ssize_t l2x0_pmu_event_show(struct device *dev,
                                   struct device_attribute *attr, char *buf)
{
        struct l2x0_event_attribute *lattr;

        lattr = container_of(attr, typeof(*lattr), attr);
        return snprintf(buf, PAGE_SIZE, "config=0x%x\n", lattr->config);
}

static umode_t l2x0_pmu_event_attr_is_visible(struct kobject *kobj,
                                              struct attribute *attr,
                                              int unused)
{
        struct device *dev = kobj_to_dev(kobj);
        struct pmu *pmu = dev_get_drvdata(dev);
        struct l2x0_event_attribute *lattr;

        lattr = container_of(attr, typeof(*lattr), attr.attr);

        if (!lattr->pl310_only || strcmp("l2c_310", pmu->name) == 0)
                return attr->mode;

        return 0;
}

static struct attribute *l2x0_pmu_event_attrs[] = {
        L220_PLUS_EVENT_ATTR(co,        0x1),
        L220_PLUS_EVENT_ATTR(drhit,     0x2),
        L220_PLUS_EVENT_ATTR(drreq,     0x3),
        L220_PLUS_EVENT_ATTR(dwhit,     0x4),
        L220_PLUS_EVENT_ATTR(dwreq,     0x5),
        L220_PLUS_EVENT_ATTR(dwtreq,    0x6),
        L220_PLUS_EVENT_ATTR(irhit,     0x7),
        L220_PLUS_EVENT_ATTR(irreq,     0x8),
        L220_PLUS_EVENT_ATTR(wa,        0x9),
        PL310_EVENT_ATTR(ipfalloc,      0xa),
        PL310_EVENT_ATTR(epfhit,        0xb),
        PL310_EVENT_ATTR(epfalloc,      0xc),
        PL310_EVENT_ATTR(srrcvd,        0xd),
        PL310_EVENT_ATTR(srconf,        0xe),
        PL310_EVENT_ATTR(epfrcvd,       0xf),
        NULL
};

static struct attribute_group l2x0_pmu_event_attrs_group = {
        .name = "events",
        .attrs = l2x0_pmu_event_attrs,
        .is_visible = l2x0_pmu_event_attr_is_visible,
};

static ssize_t l2x0_pmu_cpumask_show(struct device *dev,
                                     struct device_attribute *attr, char *buf)
{
        return cpumap_print_to_pagebuf(true, buf, &pmu_cpu);
}

static struct device_attribute l2x0_pmu_cpumask_attr =
                __ATTR(cpumask, S_IRUGO, l2x0_pmu_cpumask_show, NULL);

static struct attribute *l2x0_pmu_cpumask_attrs[] = {
        &l2x0_pmu_cpumask_attr.attr,
        NULL,
};

static struct attribute_group l2x0_pmu_cpumask_attr_group = {
        .attrs = l2x0_pmu_cpumask_attrs,
};

static const struct attribute_group *l2x0_pmu_attr_groups[] = {
        &l2x0_pmu_event_attrs_group,
        &l2x0_pmu_cpumask_attr_group,
        NULL,
};

static void l2x0_pmu_reset(void)
{
        int i;

        __l2x0_pmu_disable();

        for (i = 0; i < PMU_NR_COUNTERS; i++)
                __l2x0_pmu_event_disable(i);
}

static int l2x0_pmu_offline_cpu(unsigned int cpu)
{
        unsigned int target;

        if (!cpumask_test_and_clear_cpu(cpu, &pmu_cpu))
                return 0;

        target = cpumask_any_but(cpu_online_mask, cpu);
        if (target >= nr_cpu_ids)
                return 0;

        perf_pmu_migrate_context(l2x0_pmu, cpu, target);
        cpumask_set_cpu(target, &pmu_cpu);

        return 0;
}

void l2x0_pmu_suspend(void)
{
        int i;

        if (!l2x0_pmu)
                return;

        l2x0_pmu_disable(l2x0_pmu);

        for (i = 0; i < PMU_NR_COUNTERS; i++) {
                if (events[i])
                        l2x0_pmu_event_stop(events[i], PERF_EF_UPDATE);
        }

}

void l2x0_pmu_resume(void)
{
        int i;

        if (!l2x0_pmu)
                return;

        l2x0_pmu_reset();

        for (i = 0; i < PMU_NR_COUNTERS; i++) {
                if (events[i])
                        l2x0_pmu_event_start(events[i], PERF_EF_RELOAD);
        }

        l2x0_pmu_enable(l2x0_pmu);
}

void __init l2x0_pmu_register(void __iomem *base, u32 part)
{
        /*
         * Determine whether we support the PMU, and choose the name for sysfs.
         * This is also used by l2x0_pmu_event_attr_is_visible to determine
         * which events to display, as the PL310 PMU supports a superset of
         * L220 events.
         *
         * The L210 PMU has a different programmer's interface, and is not
         * supported by this driver.
         *
         * We must defer registering the PMU until the perf subsystem is up and
         * running, so just stash the name and base, and leave that to another
         * initcall.
         */
        switch (part & L2X0_CACHE_ID_PART_MASK) {
        case L2X0_CACHE_ID_PART_L220:
                l2x0_name = "l2c_220";
                break;
        case L2X0_CACHE_ID_PART_L310:
                l2x0_name = "l2c_310";
                break;
        default:
                return;
        }

        l2x0_base = base;
}

static __init int l2x0_pmu_init(void)
{
        int ret;

        if (!l2x0_base)
                return 0;

        l2x0_pmu = kzalloc(sizeof(*l2x0_pmu), GFP_KERNEL);
        if (!l2x0_pmu) {
                pr_warn("Unable to allocate L2x0 PMU\n");
                return -ENOMEM;
        }

        *l2x0_pmu = (struct pmu) {
                .task_ctx_nr = perf_invalid_context,
                .pmu_enable = l2x0_pmu_enable,
                .pmu_disable = l2x0_pmu_disable,
                .read = l2x0_pmu_event_read,
                .start = l2x0_pmu_event_start,
                .stop = l2x0_pmu_event_stop,
                .add = l2x0_pmu_event_add,
                .del = l2x0_pmu_event_del,
                .event_init = l2x0_pmu_event_init,
                .attr_groups = l2x0_pmu_attr_groups,
        };

        l2x0_pmu_reset();

        /*
         * We always use a hrtimer rather than an interrupt.
         * See comments in l2x0_pmu_event_configure and l2x0_pmu_poll.
         *
         * Polling once a second allows the counters to fill up to 1/128th on a
         * quad-core test chip with cores clocked at 400MHz. Hopefully this
         * leaves sufficient headroom to avoid overflow on production silicon
         * at higher frequencies.
         */
        l2x0_pmu_poll_period = ms_to_ktime(1000);
        hrtimer_init(&l2x0_pmu_hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
        l2x0_pmu_hrtimer.function = l2x0_pmu_poll;

        cpumask_set_cpu(0, &pmu_cpu);
        ret = cpuhp_setup_state_nocalls(CPUHP_AP_PERF_ARM_L2X0_ONLINE,
                                        "AP_PERF_ARM_L2X0_ONLINE", NULL,
                                        l2x0_pmu_offline_cpu);
        if (ret)
                goto out_pmu;

        ret = perf_pmu_register(l2x0_pmu, l2x0_name, -1);
        if (ret)
                goto out_cpuhp;

        return 0;

out_cpuhp:
        cpuhp_remove_state_nocalls(CPUHP_AP_PERF_ARM_L2X0_ONLINE);
out_pmu:
        kfree(l2x0_pmu);
        l2x0_pmu = NULL;
        return ret;
}
device_initcall(l2x0_pmu_init);