ARM: 6070/1: perf-events: add support for xscale PMUs

The perf-events framework for ARM only supports v6 and v7 cores.

This patch adds support for xscale v1 and v2 PMUs to perf, based on the
OProfile drivers in arch/arm/oprofile/op_model_xscale.c

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 821 insertions, 6 deletions

diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index 10a0bcdf2158..381f1211233e 100644
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -2108,6 +2108,803 @@ static u32 __init armv7_reset_read_pmnc(void)
         return nb_cnt + 1;
 }
 
+/*
+ * ARMv5 [xscale] Performance counter handling code.
+ *
+ * Based on xscale OProfile code.
+ *
+ * There are two variants of the xscale PMU that we support:
+ *      - xscale1pmu: 2 event counters and a cycle counter
+ *      - xscale2pmu: 4 event counters and a cycle counter
+ * The two variants share event definitions, but have different
+ * PMU structures.
+ */
+
+enum xscale_perf_types {
+        XSCALE_PERFCTR_ICACHE_MISS              = 0x00,
+        XSCALE_PERFCTR_ICACHE_NO_DELIVER        = 0x01,
+        XSCALE_PERFCTR_DATA_STALL               = 0x02,
+        XSCALE_PERFCTR_ITLB_MISS                = 0x03,
+        XSCALE_PERFCTR_DTLB_MISS                = 0x04,
+        XSCALE_PERFCTR_BRANCH                   = 0x05,
+        XSCALE_PERFCTR_BRANCH_MISS              = 0x06,
+        XSCALE_PERFCTR_INSTRUCTION              = 0x07,
+        XSCALE_PERFCTR_DCACHE_FULL_STALL        = 0x08,
+        XSCALE_PERFCTR_DCACHE_FULL_STALL_CONTIG = 0x09,
+        XSCALE_PERFCTR_DCACHE_ACCESS            = 0x0A,
+        XSCALE_PERFCTR_DCACHE_MISS              = 0x0B,
+        XSCALE_PERFCTR_DCACHE_WRITE_BACK        = 0x0C,
+        XSCALE_PERFCTR_PC_CHANGED               = 0x0D,
+        XSCALE_PERFCTR_BCU_REQUEST              = 0x10,
+        XSCALE_PERFCTR_BCU_FULL                 = 0x11,
+        XSCALE_PERFCTR_BCU_DRAIN                = 0x12,
+        XSCALE_PERFCTR_BCU_ECC_NO_ELOG          = 0x14,
+        XSCALE_PERFCTR_BCU_1_BIT_ERR            = 0x15,
+        XSCALE_PERFCTR_RMW                      = 0x16,
+        /* XSCALE_PERFCTR_CCNT is not hardware defined */
+        XSCALE_PERFCTR_CCNT                     = 0xFE,
+        XSCALE_PERFCTR_UNUSED                   = 0xFF,
+};
+
+enum xscale_counters {
+        XSCALE_CYCLE_COUNTER    = 1,
+        XSCALE_COUNTER0,
+        XSCALE_COUNTER1,
+        XSCALE_COUNTER2,
+        XSCALE_COUNTER3,
+};
+
+static const unsigned xscale_perf_map[PERF_COUNT_HW_MAX] = {
+        [PERF_COUNT_HW_CPU_CYCLES]          = XSCALE_PERFCTR_CCNT,
+        [PERF_COUNT_HW_INSTRUCTIONS]        = XSCALE_PERFCTR_INSTRUCTION,
+        [PERF_COUNT_HW_CACHE_REFERENCES]    = HW_OP_UNSUPPORTED,
+        [PERF_COUNT_HW_CACHE_MISSES]        = HW_OP_UNSUPPORTED,
+        [PERF_COUNT_HW_BRANCH_INSTRUCTIONS] = XSCALE_PERFCTR_BRANCH,
+        [PERF_COUNT_HW_BRANCH_MISSES]       = XSCALE_PERFCTR_BRANCH_MISS,
+        [PERF_COUNT_HW_BUS_CYCLES]          = HW_OP_UNSUPPORTED,
+};
+
+static const unsigned xscale_perf_cache_map[PERF_COUNT_HW_CACHE_MAX]
+                                           [PERF_COUNT_HW_CACHE_OP_MAX]
+                                           [PERF_COUNT_HW_CACHE_RESULT_MAX] = {
+        [C(L1D)] = {
+                [C(OP_READ)] = {
+                        [C(RESULT_ACCESS)]      = XSCALE_PERFCTR_DCACHE_ACCESS,
+                        [C(RESULT_MISS)]        = XSCALE_PERFCTR_DCACHE_MISS,
+                },
+                [C(OP_WRITE)] = {
+                        [C(RESULT_ACCESS)]      = XSCALE_PERFCTR_DCACHE_ACCESS,
+                        [C(RESULT_MISS)]        = XSCALE_PERFCTR_DCACHE_MISS,
+                },
+                [C(OP_PREFETCH)] = {
+                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
+                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
+                },
+        },
+        [C(L1I)] = {
+                [C(OP_READ)] = {
+                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
+                        [C(RESULT_MISS)]        = XSCALE_PERFCTR_ICACHE_MISS,
+                },
+                [C(OP_WRITE)] = {
+                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
+                        [C(RESULT_MISS)]        = XSCALE_PERFCTR_ICACHE_MISS,
+                },
+                [C(OP_PREFETCH)] = {
+                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
+                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
+                },
+        },
+        [C(LL)] = {
+                [C(OP_READ)] = {
+                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
+                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
+                },
+                [C(OP_WRITE)] = {
+                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
+                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
+                },
+                [C(OP_PREFETCH)] = {
+                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
+                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
+                },
+        },
+        [C(DTLB)] = {
+                [C(OP_READ)] = {
+                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
+                        [C(RESULT_MISS)]        = XSCALE_PERFCTR_DTLB_MISS,
+                },
+                [C(OP_WRITE)] = {
+                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
+                        [C(RESULT_MISS)]        = XSCALE_PERFCTR_DTLB_MISS,
+                },
+                [C(OP_PREFETCH)] = {
+                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
+                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
+                },
+        },
+        [C(ITLB)] = {
+                [C(OP_READ)] = {
+                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
+                        [C(RESULT_MISS)]        = XSCALE_PERFCTR_ITLB_MISS,
+                },
+                [C(OP_WRITE)] = {
+                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
+                        [C(RESULT_MISS)]        = XSCALE_PERFCTR_ITLB_MISS,
+                },
+                [C(OP_PREFETCH)] = {
+                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
+                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
+                },
+        },
+        [C(BPU)] = {
+                [C(OP_READ)] = {
+                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
+                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
+                },
+                [C(OP_WRITE)] = {
+                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
+                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
+                },
+                [C(OP_PREFETCH)] = {
+                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
+                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
+                },
+        },
+};
+
+#define XSCALE_PMU_ENABLE       0x001
+#define XSCALE_PMN_RESET        0x002
+#define XSCALE_CCNT_RESET       0x004
+#define XSCALE_PMU_RESET        (CCNT_RESET | PMN_RESET)
+#define XSCALE_PMU_CNT64        0x008
+
+static inline int
+xscalepmu_event_map(int config)
+{
+        int mapping = xscale_perf_map[config];
+        if (HW_OP_UNSUPPORTED == mapping)
+                mapping = -EOPNOTSUPP;
+        return mapping;
+}
+
+static u64
+xscalepmu_raw_event(u64 config)
+{
+        return config & 0xff;
+}
+
+#define XSCALE1_OVERFLOWED_MASK 0x700
+#define XSCALE1_CCOUNT_OVERFLOW 0x400
+#define XSCALE1_COUNT0_OVERFLOW 0x100
+#define XSCALE1_COUNT1_OVERFLOW 0x200
+#define XSCALE1_CCOUNT_INT_EN   0x040
+#define XSCALE1_COUNT0_INT_EN   0x010
+#define XSCALE1_COUNT1_INT_EN   0x020
+#define XSCALE1_COUNT0_EVT_SHFT 12
+#define XSCALE1_COUNT0_EVT_MASK (0xff << XSCALE1_COUNT0_EVT_SHFT)
+#define XSCALE1_COUNT1_EVT_SHFT 20
+#define XSCALE1_COUNT1_EVT_MASK (0xff << XSCALE1_COUNT1_EVT_SHFT)
+
+static inline u32
+xscale1pmu_read_pmnc(void)
+{
+        u32 val;
+        asm volatile("mrc p14, 0, %0, c0, c0, 0" : "=r" (val));
+        return val;
+}
+
+static inline void
+xscale1pmu_write_pmnc(u32 val)
+{
+        /* upper 4bits and 7, 11 are write-as-0 */
+        val &= 0xffff77f;
+        asm volatile("mcr p14, 0, %0, c0, c0, 0" : : "r" (val));
+}
+
+static inline int
+xscale1_pmnc_counter_has_overflowed(unsigned long pmnc,
+                                        enum xscale_counters counter)
+{
+        int ret = 0;
+
+        switch (counter) {
+        case XSCALE_CYCLE_COUNTER:
+                ret = pmnc & XSCALE1_CCOUNT_OVERFLOW;
+                break;
+        case XSCALE_COUNTER0:
+                ret = pmnc & XSCALE1_COUNT0_OVERFLOW;
+                break;
+        case XSCALE_COUNTER1:
+                ret = pmnc & XSCALE1_COUNT1_OVERFLOW;
+                break;
+        default:
+                WARN_ONCE(1, "invalid counter number (%d)\n", counter);
+        }
+
+        return ret;
+}
+
+static irqreturn_t
+xscale1pmu_handle_irq(int irq_num, void *dev)
+{
+        unsigned long pmnc;
+        struct perf_sample_data data;
+        struct cpu_hw_events *cpuc;
+        struct pt_regs *regs;
+        int idx;
+
+        /*
+         * NOTE: there's an A stepping erratum that states if an overflow
+         *       bit already exists and another occurs, the previous
+         *       Overflow bit gets cleared. There's no workaround.
+         *       Fixed in B stepping or later.
+         */
+        pmnc = xscale1pmu_read_pmnc();
+
+        /*
+         * Write the value back to clear the overflow flags. Overflow
+         * flags remain in pmnc for use below. We also disable the PMU
+         * while we process the interrupt.
+         */
+        xscale1pmu_write_pmnc(pmnc & ~XSCALE_PMU_ENABLE);
+
+        if (!(pmnc & XSCALE1_OVERFLOWED_MASK))
+                return IRQ_NONE;
+
+        regs = get_irq_regs();
+
+        perf_sample_data_init(&data, 0);
+
+        cpuc = &__get_cpu_var(cpu_hw_events);
+        for (idx = 0; idx <= armpmu->num_events; ++idx) {
+                struct perf_event *event = cpuc->events[idx];
+                struct hw_perf_event *hwc;
+
+                if (!test_bit(idx, cpuc->active_mask))
+                        continue;
+
+                if (!xscale1_pmnc_counter_has_overflowed(pmnc, idx))
+                        continue;
+
+                hwc = &event->hw;
+                armpmu_event_update(event, hwc, idx);
+                data.period = event->hw.last_period;
+                if (!armpmu_event_set_period(event, hwc, idx))
+                        continue;
+
+                if (perf_event_overflow(event, 0, &data, regs))
+                        armpmu->disable(hwc, idx);
+        }
+
+        perf_event_do_pending();
+
+        /*
+         * Re-enable the PMU.
+         */
+        pmnc = xscale1pmu_read_pmnc() | XSCALE_PMU_ENABLE;
+        xscale1pmu_write_pmnc(pmnc);
+
+        return IRQ_HANDLED;
+}
+
+static void
+xscale1pmu_enable_event(struct hw_perf_event *hwc, int idx)
+{
+        unsigned long val, mask, evt, flags;
+
+        switch (idx) {
+        case XSCALE_CYCLE_COUNTER:
+                mask = 0;
+                evt = XSCALE1_CCOUNT_INT_EN;
+                break;
+        case XSCALE_COUNTER0:
+                mask = XSCALE1_COUNT0_EVT_MASK;
+                evt = (hwc->config_base << XSCALE1_COUNT0_EVT_SHFT) |
+                        XSCALE1_COUNT0_INT_EN;
+                break;
+        case XSCALE_COUNTER1:
+                mask = XSCALE1_COUNT1_EVT_MASK;
+                evt = (hwc->config_base << XSCALE1_COUNT1_EVT_SHFT) |
+                        XSCALE1_COUNT1_INT_EN;
+                break;
+        default:
+                WARN_ONCE(1, "invalid counter number (%d)\n", idx);
+                return;
+        }
+
+        spin_lock_irqsave(&pmu_lock, flags);
+        val = xscale1pmu_read_pmnc();
+        val &= ~mask;
+        val |= evt;
+        xscale1pmu_write_pmnc(val);
+        spin_unlock_irqrestore(&pmu_lock, flags);
+}
+
+static void
+xscale1pmu_disable_event(struct hw_perf_event *hwc, int idx)
+{
+        unsigned long val, mask, evt, flags;
+
+        switch (idx) {
+        case XSCALE_CYCLE_COUNTER:
+                mask = XSCALE1_CCOUNT_INT_EN;
+                evt = 0;
+                break;
+        case XSCALE_COUNTER0:
+                mask = XSCALE1_COUNT0_INT_EN | XSCALE1_COUNT0_EVT_MASK;
+                evt = XSCALE_PERFCTR_UNUSED << XSCALE1_COUNT0_EVT_SHFT;
+                break;
+        case XSCALE_COUNTER1:
+                mask = XSCALE1_COUNT1_INT_EN | XSCALE1_COUNT1_EVT_MASK;
+                evt = XSCALE_PERFCTR_UNUSED << XSCALE1_COUNT1_EVT_SHFT;
+                break;
+        default:
+                WARN_ONCE(1, "invalid counter number (%d)\n", idx);
+                return;
+        }
+
+        spin_lock_irqsave(&pmu_lock, flags);
+        val = xscale1pmu_read_pmnc();
+        val &= ~mask;
+        val |= evt;
+        xscale1pmu_write_pmnc(val);
+        spin_unlock_irqrestore(&pmu_lock, flags);
+}
+
+static int
+xscale1pmu_get_event_idx(struct cpu_hw_events *cpuc,
+                        struct hw_perf_event *event)
+{
+        if (XSCALE_PERFCTR_CCNT == event->config_base) {
+                if (test_and_set_bit(XSCALE_CYCLE_COUNTER, cpuc->used_mask))
+                        return -EAGAIN;
+
+                return XSCALE_CYCLE_COUNTER;
+        } else {
+                if (!test_and_set_bit(XSCALE_COUNTER1, cpuc->used_mask)) {
+                        return XSCALE_COUNTER1;
+                }
+
+                if (!test_and_set_bit(XSCALE_COUNTER0, cpuc->used_mask)) {
+                        return XSCALE_COUNTER0;
+                }
+
+                return -EAGAIN;
+        }
+}
+
+static void
+xscale1pmu_start(void)
+{
+        unsigned long flags, val;
+
+        spin_lock_irqsave(&pmu_lock, flags);
+        val = xscale1pmu_read_pmnc();
+        val |= XSCALE_PMU_ENABLE;
+        xscale1pmu_write_pmnc(val);
+        spin_unlock_irqrestore(&pmu_lock, flags);
+}
+
+static void
+xscale1pmu_stop(void)
+{
+        unsigned long flags, val;
+
+        spin_lock_irqsave(&pmu_lock, flags);
+        val = xscale1pmu_read_pmnc();
+        val &= ~XSCALE_PMU_ENABLE;
+        xscale1pmu_write_pmnc(val);
+        spin_unlock_irqrestore(&pmu_lock, flags);
+}
+
+static inline u32
+xscale1pmu_read_counter(int counter)
+{
+        u32 val = 0;
+
+        switch (counter) {
+        case XSCALE_CYCLE_COUNTER:
+                asm volatile("mrc p14, 0, %0, c1, c0, 0" : "=r" (val));
+                break;
+        case XSCALE_COUNTER0:
+                asm volatile("mrc p14, 0, %0, c2, c0, 0" : "=r" (val));
+                break;
+        case XSCALE_COUNTER1:
+                asm volatile("mrc p14, 0, %0, c3, c0, 0" : "=r" (val));
+                break;
+        }
+
+        return val;
+}
+
+static inline void
+xscale1pmu_write_counter(int counter, u32 val)
+{
+        switch (counter) {
+        case XSCALE_CYCLE_COUNTER:
+                asm volatile("mcr p14, 0, %0, c1, c0, 0" : : "r" (val));
+                break;
+        case XSCALE_COUNTER0:
+                asm volatile("mcr p14, 0, %0, c2, c0, 0" : : "r" (val));
+                break;
+        case XSCALE_COUNTER1:
+                asm volatile("mcr p14, 0, %0, c3, c0, 0" : : "r" (val));
+                break;
+        }
+}
+
+static const struct arm_pmu xscale1pmu = {
+        .id             = ARM_PERF_PMU_ID_XSCALE1,
+        .handle_irq     = xscale1pmu_handle_irq,
+        .enable         = xscale1pmu_enable_event,
+        .disable        = xscale1pmu_disable_event,
+        .event_map      = xscalepmu_event_map,
+        .raw_event      = xscalepmu_raw_event,
+        .read_counter   = xscale1pmu_read_counter,
+        .write_counter  = xscale1pmu_write_counter,
+        .get_event_idx  = xscale1pmu_get_event_idx,
+        .start          = xscale1pmu_start,
+        .stop           = xscale1pmu_stop,
+        .num_events     = 3,
+        .max_period     = (1LLU << 32) - 1,
+};
+
+#define XSCALE2_OVERFLOWED_MASK 0x01f
+#define XSCALE2_CCOUNT_OVERFLOW 0x001
+#define XSCALE2_COUNT0_OVERFLOW 0x002
+#define XSCALE2_COUNT1_OVERFLOW 0x004
+#define XSCALE2_COUNT2_OVERFLOW 0x008
+#define XSCALE2_COUNT3_OVERFLOW 0x010
+#define XSCALE2_CCOUNT_INT_EN   0x001
+#define XSCALE2_COUNT0_INT_EN   0x002
+#define XSCALE2_COUNT1_INT_EN   0x004
+#define XSCALE2_COUNT2_INT_EN   0x008
+#define XSCALE2_COUNT3_INT_EN   0x010
+#define XSCALE2_COUNT0_EVT_SHFT 0
+#define XSCALE2_COUNT0_EVT_MASK (0xff << XSCALE2_COUNT0_EVT_SHFT)
+#define XSCALE2_COUNT1_EVT_SHFT 8
+#define XSCALE2_COUNT1_EVT_MASK (0xff << XSCALE2_COUNT1_EVT_SHFT)
+#define XSCALE2_COUNT2_EVT_SHFT 16
+#define XSCALE2_COUNT2_EVT_MASK (0xff << XSCALE2_COUNT2_EVT_SHFT)
+#define XSCALE2_COUNT3_EVT_SHFT 24
+#define XSCALE2_COUNT3_EVT_MASK (0xff << XSCALE2_COUNT3_EVT_SHFT)
+
+static inline u32
+xscale2pmu_read_pmnc(void)
+{
+        u32 val;
+        asm volatile("mrc p14, 0, %0, c0, c1, 0" : "=r" (val));
+        /* bits 1-2 and 4-23 are read-unpredictable */
+        return val & 0xff000009;
+}
+
+static inline void
+xscale2pmu_write_pmnc(u32 val)
+{
+        /* bits 4-23 are write-as-0, 24-31 are write ignored */
+        val &= 0xf;
+        asm volatile("mcr p14, 0, %0, c0, c1, 0" : : "r" (val));
+}
+
+static inline u32
+xscale2pmu_read_overflow_flags(void)
+{
+        u32 val;
+        asm volatile("mrc p14, 0, %0, c5, c1, 0" : "=r" (val));
+        return val;
+}
+
+static inline void
+xscale2pmu_write_overflow_flags(u32 val)
+{
+        asm volatile("mcr p14, 0, %0, c5, c1, 0" : : "r" (val));
+}
+
+static inline u32
+xscale2pmu_read_event_select(void)
+{
+        u32 val;
+        asm volatile("mrc p14, 0, %0, c8, c1, 0" : "=r" (val));
+        return val;
+}
+
+static inline void
+xscale2pmu_write_event_select(u32 val)
+{
+        asm volatile("mcr p14, 0, %0, c8, c1, 0" : : "r"(val));
+}
+
+static inline u32
+xscale2pmu_read_int_enable(void)
+{
+        u32 val;
+        asm volatile("mrc p14, 0, %0, c4, c1, 0" : "=r" (val));
+        return val;
+}
+
+static void
+xscale2pmu_write_int_enable(u32 val)
+{
+        asm volatile("mcr p14, 0, %0, c4, c1, 0" : : "r" (val));
+}
+
+static inline int
+xscale2_pmnc_counter_has_overflowed(unsigned long of_flags,
+                                        enum xscale_counters counter)
+{
+        int ret = 0;
+
+        switch (counter) {
+        case XSCALE_CYCLE_COUNTER:
+                ret = of_flags & XSCALE2_CCOUNT_OVERFLOW;
+                break;
+        case XSCALE_COUNTER0:
+                ret = of_flags & XSCALE2_COUNT0_OVERFLOW;
+                break;
+        case XSCALE_COUNTER1:
+                ret = of_flags & XSCALE2_COUNT1_OVERFLOW;
+                break;
+        case XSCALE_COUNTER2:
+                ret = of_flags & XSCALE2_COUNT2_OVERFLOW;
+                break;
+        case XSCALE_COUNTER3:
+                ret = of_flags & XSCALE2_COUNT3_OVERFLOW;
+                break;
+        default:
+                WARN_ONCE(1, "invalid counter number (%d)\n", counter);
+        }
+
+        return ret;
+}
+
+static irqreturn_t
+xscale2pmu_handle_irq(int irq_num, void *dev)
+{
+        unsigned long pmnc, of_flags;
+        struct perf_sample_data data;
+        struct cpu_hw_events *cpuc;
+        struct pt_regs *regs;
+        int idx;
+
+        /* Disable the PMU. */
+        pmnc = xscale2pmu_read_pmnc();
+        xscale2pmu_write_pmnc(pmnc & ~XSCALE_PMU_ENABLE);
+
+        /* Check the overflow flag register. */
+        of_flags = xscale2pmu_read_overflow_flags();
+        if (!(of_flags & XSCALE2_OVERFLOWED_MASK))
+                return IRQ_NONE;
+
+        /* Clear the overflow bits. */
+        xscale2pmu_write_overflow_flags(of_flags);
+
+        regs = get_irq_regs();
+
+        perf_sample_data_init(&data, 0);
+
+        cpuc = &__get_cpu_var(cpu_hw_events);
+        for (idx = 0; idx <= armpmu->num_events; ++idx) {
+                struct perf_event *event = cpuc->events[idx];
+                struct hw_perf_event *hwc;
+
+                if (!test_bit(idx, cpuc->active_mask))
+                        continue;
+
+                if (!xscale2_pmnc_counter_has_overflowed(pmnc, idx))
+                        continue;
+
+                hwc = &event->hw;
+                armpmu_event_update(event, hwc, idx);
+                data.period = event->hw.last_period;
+                if (!armpmu_event_set_period(event, hwc, idx))
+                        continue;
+
+                if (perf_event_overflow(event, 0, &data, regs))
+                        armpmu->disable(hwc, idx);
+        }
+
+        perf_event_do_pending();
+
+        /*
+         * Re-enable the PMU.
+         */
+        pmnc = xscale2pmu_read_pmnc() | XSCALE_PMU_ENABLE;
+        xscale2pmu_write_pmnc(pmnc);
+
+        return IRQ_HANDLED;
+}
+
+static void
+xscale2pmu_enable_event(struct hw_perf_event *hwc, int idx)
+{
+        unsigned long flags, ien, evtsel;
+
+        ien = xscale2pmu_read_int_enable();
+        evtsel = xscale2pmu_read_event_select();
+
+        switch (idx) {
+        case XSCALE_CYCLE_COUNTER:
+                ien |= XSCALE2_CCOUNT_INT_EN;
+                break;
+        case XSCALE_COUNTER0:
+                ien |= XSCALE2_COUNT0_INT_EN;
+                evtsel &= ~XSCALE2_COUNT0_EVT_MASK;
+                evtsel |= hwc->config_base << XSCALE2_COUNT0_EVT_SHFT;
+                break;
+        case XSCALE_COUNTER1:
+                ien |= XSCALE2_COUNT1_INT_EN;
+                evtsel &= ~XSCALE2_COUNT1_EVT_MASK;
+                evtsel |= hwc->config_base << XSCALE2_COUNT1_EVT_SHFT;
+                break;
+        case XSCALE_COUNTER2:
+                ien |= XSCALE2_COUNT2_INT_EN;
+                evtsel &= ~XSCALE2_COUNT2_EVT_MASK;
+                evtsel |= hwc->config_base << XSCALE2_COUNT2_EVT_SHFT;
+                break;
+        case XSCALE_COUNTER3:
+                ien |= XSCALE2_COUNT3_INT_EN;
+                evtsel &= ~XSCALE2_COUNT3_EVT_MASK;
+                evtsel |= hwc->config_base << XSCALE2_COUNT3_EVT_SHFT;
+                break;
+        default:
+                WARN_ONCE(1, "invalid counter number (%d)\n", idx);
+                return;
+        }
+
+        spin_lock_irqsave(&pmu_lock, flags);
+        xscale2pmu_write_event_select(evtsel);
+        xscale2pmu_write_int_enable(ien);
+        spin_unlock_irqrestore(&pmu_lock, flags);
+}
+
+static void
+xscale2pmu_disable_event(struct hw_perf_event *hwc, int idx)
+{
+        unsigned long flags, ien, evtsel;
+
+        ien = xscale2pmu_read_int_enable();
+        evtsel = xscale2pmu_read_event_select();
+
+        switch (idx) {
+        case XSCALE_CYCLE_COUNTER:
+                ien &= ~XSCALE2_CCOUNT_INT_EN;
+                break;
+        case XSCALE_COUNTER0:
+                ien &= ~XSCALE2_COUNT0_INT_EN;
+                evtsel &= ~XSCALE2_COUNT0_EVT_MASK;
+                evtsel |= XSCALE_PERFCTR_UNUSED << XSCALE2_COUNT0_EVT_SHFT;
+                break;
+        case XSCALE_COUNTER1:
+                ien &= ~XSCALE2_COUNT1_INT_EN;
+                evtsel &= ~XSCALE2_COUNT1_EVT_MASK;
+                evtsel |= XSCALE_PERFCTR_UNUSED << XSCALE2_COUNT1_EVT_SHFT;
+                break;
+        case XSCALE_COUNTER2:
+                ien &= ~XSCALE2_COUNT2_INT_EN;
+                evtsel &= ~XSCALE2_COUNT2_EVT_MASK;
+                evtsel |= XSCALE_PERFCTR_UNUSED << XSCALE2_COUNT2_EVT_SHFT;
+                break;
+        case XSCALE_COUNTER3:
+                ien &= ~XSCALE2_COUNT3_INT_EN;
+                evtsel &= ~XSCALE2_COUNT3_EVT_MASK;
+                evtsel |= XSCALE_PERFCTR_UNUSED << XSCALE2_COUNT3_EVT_SHFT;
+                break;
+        default:
+                WARN_ONCE(1, "invalid counter number (%d)\n", idx);
+                return;
+        }
+
+        spin_lock_irqsave(&pmu_lock, flags);
+        xscale2pmu_write_event_select(evtsel);
+        xscale2pmu_write_int_enable(ien);
+        spin_unlock_irqrestore(&pmu_lock, flags);
+}
+
+static int
+xscale2pmu_get_event_idx(struct cpu_hw_events *cpuc,
+                        struct hw_perf_event *event)
+{
+        int idx = xscale1pmu_get_event_idx(cpuc, event);
+        if (idx >= 0)
+                goto out;
+
+        if (!test_and_set_bit(XSCALE_COUNTER3, cpuc->used_mask))
+                idx = XSCALE_COUNTER3;
+        else if (!test_and_set_bit(XSCALE_COUNTER2, cpuc->used_mask))
+                idx = XSCALE_COUNTER2;
+out:
+        return idx;
+}
+
+static void
+xscale2pmu_start(void)
+{
+        unsigned long flags, val;
+
+        spin_lock_irqsave(&pmu_lock, flags);
+        val = xscale2pmu_read_pmnc() & ~XSCALE_PMU_CNT64;
+        val |= XSCALE_PMU_ENABLE;
+        xscale2pmu_write_pmnc(val);
+        spin_unlock_irqrestore(&pmu_lock, flags);
+}
+
+static void
+xscale2pmu_stop(void)
+{
+        unsigned long flags, val;
+
+        spin_lock_irqsave(&pmu_lock, flags);
+        val = xscale2pmu_read_pmnc();
+        val &= ~XSCALE_PMU_ENABLE;
+        xscale2pmu_write_pmnc(val);
+        spin_unlock_irqrestore(&pmu_lock, flags);
+}
+
+static inline u32
+xscale2pmu_read_counter(int counter)
+{
+        u32 val = 0;
+
+        switch (counter) {
+        case XSCALE_CYCLE_COUNTER:
+                asm volatile("mrc p14, 0, %0, c1, c1, 0" : "=r" (val));
+                break;
+        case XSCALE_COUNTER0:
+                asm volatile("mrc p14, 0, %0, c0, c2, 0" : "=r" (val));
+                break;
+        case XSCALE_COUNTER1:
+                asm volatile("mrc p14, 0, %0, c1, c2, 0" : "=r" (val));
+                break;
+        case XSCALE_COUNTER2:
+                asm volatile("mrc p14, 0, %0, c2, c2, 0" : "=r" (val));
+                break;
+        case XSCALE_COUNTER3:
+                asm volatile("mrc p14, 0, %0, c3, c2, 0" : "=r" (val));
+                break;
+        }
+
+        return val;
+}
+
+static inline void
+xscale2pmu_write_counter(int counter, u32 val)
+{
+        switch (counter) {
+        case XSCALE_CYCLE_COUNTER:
+                asm volatile("mcr p14, 0, %0, c1, c1, 0" : : "r" (val));
+                break;
+        case XSCALE_COUNTER0:
+                asm volatile("mcr p14, 0, %0, c0, c2, 0" : : "r" (val));
+                break;
+        case XSCALE_COUNTER1:
+                asm volatile("mcr p14, 0, %0, c1, c2, 0" : : "r" (val));
+                break;
+        case XSCALE_COUNTER2:
+                asm volatile("mcr p14, 0, %0, c2, c2, 0" : : "r" (val));
+                break;
+        case XSCALE_COUNTER3:
+                asm volatile("mcr p14, 0, %0, c3, c2, 0" : : "r" (val));
+                break;
+        }
+}
+
+static const struct arm_pmu xscale2pmu = {
+        .id             = ARM_PERF_PMU_ID_XSCALE2,
+        .handle_irq     = xscale2pmu_handle_irq,
+        .enable         = xscale2pmu_enable_event,
+        .disable        = xscale2pmu_disable_event,
+        .event_map      = xscalepmu_event_map,
+        .raw_event      = xscalepmu_raw_event,
+        .read_counter   = xscale2pmu_read_counter,
+        .write_counter  = xscale2pmu_write_counter,
+        .get_event_idx  = xscale2pmu_get_event_idx,
+        .start          = xscale2pmu_start,
+        .stop           = xscale2pmu_stop,
+        .num_events     = 5,
+        .max_period     = (1LLU << 32) - 1,
+};
+
 static int __init
 init_hw_perf_events(void)
 {
@@ -2115,7 +2912,7 @@ init_hw_perf_events(void)
         unsigned long implementor = (cpuid & 0xFF000000) >> 24;
         unsigned long part_number = (cpuid & 0xFFF0);
 
-        /* We only support ARM CPUs implemented by ARM at the moment. */
+        /* ARM Ltd CPUs. */
         if (0x41 == implementor) {
                 switch (part_number) {
                 case 0xB360:    /* ARM1136 */
@@ -2157,15 +2954,33 @@ init_hw_perf_events(void)
                         armv7pmu.num_events = armv7_reset_read_pmnc();
                         perf_max_events = armv7pmu.num_events;
                         break;
-                default:
-                        pr_info("no hardware support available\n");
-                        perf_max_events = -1;
+                }
+        /* Intel CPUs [xscale]. */
+        } else if (0x69 == implementor) {
+                part_number = (cpuid >> 13) & 0x7;
+                switch (part_number) {
+                case 1:
+                        armpmu = &xscale1pmu;
+                        memcpy(armpmu_perf_cache_map, xscale_perf_cache_map,
+                                        sizeof(xscale_perf_cache_map));
+                        perf_max_events = xscale1pmu.num_events;
+                        break;
+                case 2:
+                        armpmu = &xscale2pmu;
+                        memcpy(armpmu_perf_cache_map, xscale_perf_cache_map,
+                                        sizeof(xscale_perf_cache_map));
+                        perf_max_events = xscale2pmu.num_events;
+                        break;
                 }
         }
 
-        if (armpmu)
+        if (armpmu) {
                 pr_info("enabled with %s PMU driver, %d counters available\n",
-                        arm_pmu_names[armpmu->id], armpmu->num_events);
+                                arm_pmu_names[armpmu->id], armpmu->num_events);
+        } else {
+                pr_info("no hardware support available\n");
+                perf_max_events = -1;
+        }
 
         return 0;
 }