// SPDX-License-Identifier: GPL-2.0
/*
 * ARMv6 Performance counter handling code.
 *
 * Copyright (C) 2009 picoChip Designs, Ltd., Jamie Iles
 *
 * ARMv6 has 2 configurable performance counters and a single cycle counter.
 * They all share a single reset bit but can be written to zero so we can use
 * that for a reset.
 *
 * The counters can't be individually enabled or disabled so when we remove
 * one event and replace it with another we could get spurious counts from the
 * wrong event. However, we can take advantage of the fact that the
 * performance counters can export events to the event bus, and the event bus
 * itself can be monitored. This requires that we *don't* export the events to
 * the event bus. The procedure for disabling a configurable counter is:
 *      - change the counter to count the ETMEXTOUT[0] signal (0x20). This
 *        effectively stops the counter from counting.
 *      - disable the counter's interrupt generation (each counter has it's
 *        own interrupt enable bit).
 * Once stopped, the counter value can be written as 0 to reset.
 *
 * To enable a counter:
 *      - enable the counter's interrupt generation.
 *      - set the new event type.
 *
 * Note: the dedicated cycle counter only counts cycles and can't be
 * enabled/disabled independently of the others. When we want to disable the
 * cycle counter, we have to just disable the interrupt reporting and start
 * ignoring that counter. When re-enabling, we have to reset the value and
 * enable the interrupt.
 */

#include <asm/cputype.h>
#include <asm/irq_regs.h>

#include <linux/of.h>
#include <linux/perf/arm_pmu.h>
#include <linux/platform_device.h>

enum armv6_perf_types {
        ARMV6_PERFCTR_ICACHE_MISS           = 0x0,
        ARMV6_PERFCTR_IBUF_STALL            = 0x1,
        ARMV6_PERFCTR_DDEP_STALL            = 0x2,
        ARMV6_PERFCTR_ITLB_MISS             = 0x3,
        ARMV6_PERFCTR_DTLB_MISS             = 0x4,
        ARMV6_PERFCTR_BR_EXEC               = 0x5,
        ARMV6_PERFCTR_BR_MISPREDICT         = 0x6,
        ARMV6_PERFCTR_INSTR_EXEC            = 0x7,
        ARMV6_PERFCTR_DCACHE_HIT            = 0x9,
        ARMV6_PERFCTR_DCACHE_ACCESS         = 0xA,
        ARMV6_PERFCTR_DCACHE_MISS           = 0xB,
        ARMV6_PERFCTR_DCACHE_WBACK          = 0xC,
        ARMV6_PERFCTR_SW_PC_CHANGE          = 0xD,
        ARMV6_PERFCTR_MAIN_TLB_MISS         = 0xF,
        ARMV6_PERFCTR_EXPL_D_ACCESS         = 0x10,
        ARMV6_PERFCTR_LSU_FULL_STALL        = 0x11,
        ARMV6_PERFCTR_WBUF_DRAINED          = 0x12,
        ARMV6_PERFCTR_CPU_CYCLES            = 0xFF,
        ARMV6_PERFCTR_NOP                   = 0x20,
};

enum armv6_counters {
        ARMV6_CYCLE_COUNTER = 0,
        ARMV6_COUNTER0,
        ARMV6_COUNTER1,
        ARMV6_NUM_COUNTERS
};

/*
 * The hardware events that we support. We do support cache operations but
 * we have harvard caches and no way to combine instruction and data
 * accesses/misses in hardware.
 */
static const unsigned armv6_perf_map[PERF_COUNT_HW_MAX] = {
        PERF_MAP_ALL_UNSUPPORTED,
        [PERF_COUNT_HW_CPU_CYCLES]              = ARMV6_PERFCTR_CPU_CYCLES,
        [PERF_COUNT_HW_INSTRUCTIONS]            = ARMV6_PERFCTR_INSTR_EXEC,
        [PERF_COUNT_HW_BRANCH_INSTRUCTIONS]     = ARMV6_PERFCTR_BR_EXEC,
        [PERF_COUNT_HW_BRANCH_MISSES]           = ARMV6_PERFCTR_BR_MISPREDICT,
        [PERF_COUNT_HW_STALLED_CYCLES_FRONTEND] = ARMV6_PERFCTR_IBUF_STALL,
        [PERF_COUNT_HW_STALLED_CYCLES_BACKEND]  = ARMV6_PERFCTR_LSU_FULL_STALL,
};

static const unsigned armv6_perf_cache_map[PERF_COUNT_HW_CACHE_MAX]
                                          [PERF_COUNT_HW_CACHE_OP_MAX]
                                          [PERF_COUNT_HW_CACHE_RESULT_MAX] = {
        PERF_CACHE_MAP_ALL_UNSUPPORTED,

        /*
         * The performance counters don't differentiate between read and write
         * accesses/misses so this isn't strictly correct, but it's the best we
         * can do. Writes and reads get combined.
         */
        [C(L1D)][C(OP_READ)][C(RESULT_ACCESS)]  = ARMV6_PERFCTR_DCACHE_ACCESS,
        [C(L1D)][C(OP_READ)][C(RESULT_MISS)]    = ARMV6_PERFCTR_DCACHE_MISS,
        [C(L1D)][C(OP_WRITE)][C(RESULT_ACCESS)] = ARMV6_PERFCTR_DCACHE_ACCESS,
        [C(L1D)][C(OP_WRITE)][C(RESULT_MISS)]   = ARMV6_PERFCTR_DCACHE_MISS,

        [C(L1I)][C(OP_READ)][C(RESULT_MISS)]    = ARMV6_PERFCTR_ICACHE_MISS,

        /*
         * The ARM performance counters can count micro DTLB misses, micro ITLB
         * misses and main TLB misses. There isn't an event for TLB misses, so
         * use the micro misses here and if users want the main TLB misses they
         * can use a raw counter.
         */
        [C(DTLB)][C(OP_READ)][C(RESULT_MISS)]   = ARMV6_PERFCTR_DTLB_MISS,
        [C(DTLB)][C(OP_WRITE)][C(RESULT_MISS)]  = ARMV6_PERFCTR_DTLB_MISS,

        [C(ITLB)][C(OP_READ)][C(RESULT_MISS)]   = ARMV6_PERFCTR_ITLB_MISS,
        [C(ITLB)][C(OP_WRITE)][C(RESULT_MISS)]  = ARMV6_PERFCTR_ITLB_MISS,
};

static inline unsigned long
armv6_pmcr_read(void)
{
        u32 val;
        asm volatile("mrc   p15, 0, %0, c15, c12, 0" : "=r"(val));
        return val;
}

static inline void
armv6_pmcr_write(unsigned long val)
{
        asm volatile("mcr   p15, 0, %0, c15, c12, 0" : : "r"(val));
}

#define ARMV6_PMCR_ENABLE               (1 << 0)
#define ARMV6_PMCR_CTR01_RESET          (1 << 1)
#define ARMV6_PMCR_CCOUNT_RESET         (1 << 2)
#define ARMV6_PMCR_CCOUNT_DIV           (1 << 3)
#define ARMV6_PMCR_COUNT0_IEN           (1 << 4)
#define ARMV6_PMCR_COUNT1_IEN           (1 << 5)
#define ARMV6_PMCR_CCOUNT_IEN           (1 << 6)
#define ARMV6_PMCR_COUNT0_OVERFLOW      (1 << 8)
#define ARMV6_PMCR_COUNT1_OVERFLOW      (1 << 9)
#define ARMV6_PMCR_CCOUNT_OVERFLOW      (1 << 10)
#define ARMV6_PMCR_EVT_COUNT0_SHIFT     20
#define ARMV6_PMCR_EVT_COUNT0_MASK      (0xFF << ARMV6_PMCR_EVT_COUNT0_SHIFT)
#define ARMV6_PMCR_EVT_COUNT1_SHIFT     12
#define ARMV6_PMCR_EVT_COUNT1_MASK      (0xFF << ARMV6_PMCR_EVT_COUNT1_SHIFT)

#define ARMV6_PMCR_OVERFLOWED_MASK \
        (ARMV6_PMCR_COUNT0_OVERFLOW | ARMV6_PMCR_COUNT1_OVERFLOW | \
         ARMV6_PMCR_CCOUNT_OVERFLOW)

static inline int
armv6_pmcr_has_overflowed(unsigned long pmcr)
{
        return pmcr & ARMV6_PMCR_OVERFLOWED_MASK;
}

static inline int
armv6_pmcr_counter_has_overflowed(unsigned long pmcr,
                                  enum armv6_counters counter)
{
        int ret = 0;

        if (ARMV6_CYCLE_COUNTER == counter)
                ret = pmcr & ARMV6_PMCR_CCOUNT_OVERFLOW;
        else if (ARMV6_COUNTER0 == counter)
                ret = pmcr & ARMV6_PMCR_COUNT0_OVERFLOW;
        else if (ARMV6_COUNTER1 == counter)
                ret = pmcr & ARMV6_PMCR_COUNT1_OVERFLOW;
        else
                WARN_ONCE(1, "invalid counter number (%d)\n", counter);

        return ret;
}

static inline u64 armv6pmu_read_counter(struct perf_event *event)
{
        struct hw_perf_event *hwc = &event->hw;
        int counter = hwc->idx;
        unsigned long value = 0;

        if (ARMV6_CYCLE_COUNTER == counter)
                asm volatile("mrc   p15, 0, %0, c15, c12, 1" : "=r"(value));
        else if (ARMV6_COUNTER0 == counter)
                asm volatile("mrc   p15, 0, %0, c15, c12, 2" : "=r"(value));
        else if (ARMV6_COUNTER1 == counter)
                asm volatile("mrc   p15, 0, %0, c15, c12, 3" : "=r"(value));
        else
                WARN_ONCE(1, "invalid counter number (%d)\n", counter);

        return value;
}

static inline void armv6pmu_write_counter(struct perf_event *event, u64 value)
{
        struct hw_perf_event *hwc = &event->hw;
        int counter = hwc->idx;

        if (ARMV6_CYCLE_COUNTER == counter)
                asm volatile("mcr   p15, 0, %0, c15, c12, 1" : : "r"(value));
        else if (ARMV6_COUNTER0 == counter)
                asm volatile("mcr   p15, 0, %0, c15, c12, 2" : : "r"(value));
        else if (ARMV6_COUNTER1 == counter)
                asm volatile("mcr   p15, 0, %0, c15, c12, 3" : : "r"(value));
        else
                WARN_ONCE(1, "invalid counter number (%d)\n", counter);
}

static void armv6pmu_enable_event(struct perf_event *event)
{
        unsigned long val, mask, evt;
        struct hw_perf_event *hwc = &event->hw;
        int idx = hwc->idx;

        if (ARMV6_CYCLE_COUNTER == idx) {
                mask    = 0;
                evt     = ARMV6_PMCR_CCOUNT_IEN;
        } else if (ARMV6_COUNTER0 == idx) {
                mask    = ARMV6_PMCR_EVT_COUNT0_MASK;
                evt     = (hwc->config_base << ARMV6_PMCR_EVT_COUNT0_SHIFT) |
                          ARMV6_PMCR_COUNT0_IEN;
        } else if (ARMV6_COUNTER1 == idx) {
                mask    = ARMV6_PMCR_EVT_COUNT1_MASK;
                evt     = (hwc->config_base << ARMV6_PMCR_EVT_COUNT1_SHIFT) |
                          ARMV6_PMCR_COUNT1_IEN;
        } else {
                WARN_ONCE(1, "invalid counter number (%d)\n", idx);
                return;
        }

        /*
         * Mask out the current event and set the counter to count the event
         * that we're interested in.
         */
        val = armv6_pmcr_read();
        val &= ~mask;
        val |= evt;
        armv6_pmcr_write(val);
}

static irqreturn_t
armv6pmu_handle_irq(struct arm_pmu *cpu_pmu)
{
        unsigned long pmcr = armv6_pmcr_read();
        struct perf_sample_data data;
        struct pmu_hw_events *cpuc = this_cpu_ptr(cpu_pmu->hw_events);
        struct pt_regs *regs;
        int idx;

        if (!armv6_pmcr_has_overflowed(pmcr))
                return IRQ_NONE;

        regs = get_irq_regs();

        /*
         * The interrupts are cleared by writing the overflow flags back to
         * the control register. All of the other bits don't have any effect
         * if they are rewritten, so write the whole value back.
         */
        armv6_pmcr_write(pmcr);

        for_each_set_bit(idx, cpu_pmu->cntr_mask, ARMV6_NUM_COUNTERS) {
                struct perf_event *event = cpuc->events[idx];
                struct hw_perf_event *hwc;

                /* Ignore if we don't have an event. */
                if (!event)
                        continue;

                /*
                 * We have a single interrupt for all counters. Check that
                 * each counter has overflowed before we process it.
                 */
                if (!armv6_pmcr_counter_has_overflowed(pmcr, idx))
                        continue;

                hwc = &event->hw;
                armpmu_event_update(event);
                perf_sample_data_init(&data, 0, hwc->last_period);
                if (!armpmu_event_set_period(event))
                        continue;

                perf_event_overflow(event, &data, regs);
        }

        /*
         * Handle the pending perf events.
         *
         * Note: this call *must* be run with interrupts disabled. For
         * platforms that can have the PMU interrupts raised as an NMI, this
         * will not work.
         */
        irq_work_run();

        return IRQ_HANDLED;
}

static void armv6pmu_start(struct arm_pmu *cpu_pmu)
{
        unsigned long val;

        val = armv6_pmcr_read();
        val |= ARMV6_PMCR_ENABLE;
        armv6_pmcr_write(val);
}

static void armv6pmu_stop(struct arm_pmu *cpu_pmu)
{
        unsigned long val;

        val = armv6_pmcr_read();
        val &= ~ARMV6_PMCR_ENABLE;
        armv6_pmcr_write(val);
}

static int
armv6pmu_get_event_idx(struct pmu_hw_events *cpuc,
                                struct perf_event *event)
{
        struct hw_perf_event *hwc = &event->hw;
        /* Always place a cycle counter into the cycle counter. */
        if (ARMV6_PERFCTR_CPU_CYCLES == hwc->config_base) {
                if (test_and_set_bit(ARMV6_CYCLE_COUNTER, cpuc->used_mask))
                        return -EAGAIN;

                return ARMV6_CYCLE_COUNTER;
        } else {
                /*
                 * For anything other than a cycle counter, try and use
                 * counter0 and counter1.
                 */
                if (!test_and_set_bit(ARMV6_COUNTER1, cpuc->used_mask))
                        return ARMV6_COUNTER1;

                if (!test_and_set_bit(ARMV6_COUNTER0, cpuc->used_mask))
                        return ARMV6_COUNTER0;

                /* The counters are all in use. */
                return -EAGAIN;
        }
}

static void armv6pmu_clear_event_idx(struct pmu_hw_events *cpuc,
                                     struct perf_event *event)
{
        clear_bit(event->hw.idx, cpuc->used_mask);
}

static void armv6pmu_disable_event(struct perf_event *event)
{
        unsigned long val, mask, evt;
        struct hw_perf_event *hwc = &event->hw;
        int idx = hwc->idx;

        if (ARMV6_CYCLE_COUNTER == idx) {
                mask    = ARMV6_PMCR_CCOUNT_IEN;
                evt     = 0;
        } else if (ARMV6_COUNTER0 == idx) {
                mask    = ARMV6_PMCR_COUNT0_IEN | ARMV6_PMCR_EVT_COUNT0_MASK;
                evt     = ARMV6_PERFCTR_NOP << ARMV6_PMCR_EVT_COUNT0_SHIFT;
        } else if (ARMV6_COUNTER1 == idx) {
                mask    = ARMV6_PMCR_COUNT1_IEN | ARMV6_PMCR_EVT_COUNT1_MASK;
                evt     = ARMV6_PERFCTR_NOP << ARMV6_PMCR_EVT_COUNT1_SHIFT;
        } else {
                WARN_ONCE(1, "invalid counter number (%d)\n", idx);
                return;
        }

        /*
         * Mask out the current event and set the counter to count the number
         * of ETM bus signal assertion cycles. The external reporting should
         * be disabled and so this should never increment.
         */
        val = armv6_pmcr_read();
        val &= ~mask;
        val |= evt;
        armv6_pmcr_write(val);
}

static int armv6_map_event(struct perf_event *event)
{
        return armpmu_map_event(event, &armv6_perf_map,
                                &armv6_perf_cache_map, 0xFF);
}

static void armv6pmu_init(struct arm_pmu *cpu_pmu)
{
        cpu_pmu->handle_irq     = armv6pmu_handle_irq;
        cpu_pmu->enable         = armv6pmu_enable_event;
        cpu_pmu->disable        = armv6pmu_disable_event;
        cpu_pmu->read_counter   = armv6pmu_read_counter;
        cpu_pmu->write_counter  = armv6pmu_write_counter;
        cpu_pmu->get_event_idx  = armv6pmu_get_event_idx;
        cpu_pmu->clear_event_idx = armv6pmu_clear_event_idx;
        cpu_pmu->start          = armv6pmu_start;
        cpu_pmu->stop           = armv6pmu_stop;
        cpu_pmu->map_event      = armv6_map_event;

        bitmap_set(cpu_pmu->cntr_mask, 0, ARMV6_NUM_COUNTERS);
}

static int armv6_1136_pmu_init(struct arm_pmu *cpu_pmu)
{
        armv6pmu_init(cpu_pmu);
        cpu_pmu->name           = "armv6_1136";
        return 0;
}

static int armv6_1176_pmu_init(struct arm_pmu *cpu_pmu)
{
        armv6pmu_init(cpu_pmu);
        cpu_pmu->name           = "armv6_1176";
        return 0;
}

static const struct of_device_id armv6_pmu_of_device_ids[] = {
        {.compatible = "arm,arm1176-pmu",       .data = armv6_1176_pmu_init},
        {.compatible = "arm,arm1136-pmu",       .data = armv6_1136_pmu_init},
        { /* sentinel value */ }
};

static int armv6_pmu_device_probe(struct platform_device *pdev)
{
        return arm_pmu_device_probe(pdev, armv6_pmu_of_device_ids, NULL);
}

static struct platform_driver armv6_pmu_driver = {
        .driver         = {
                .name   = "armv6-pmu",
                .of_match_table = armv6_pmu_of_device_ids,
        },
        .probe          = armv6_pmu_device_probe,
};

builtin_platform_driver(armv6_pmu_driver);